To save on fuel and reduce aircraft emissions, engineers are looking to build lighter, stronger airplanes out of advanced composites. These engineered materials are made from high-performance fibers that are embedded in polymer sheets. The sheets can be stacked and pressed into one multilayered material and made into extremely lightweight and durable structures.

But composite materials have one main vulnerability: the space between layers, which is typically filled with polymer “glue” to bond the layers together. In the event of an impact or strike, cracks can easily spread between layers and weaken the material, even though there may be no visible damage to the layers themselves. Over time, as these hidden cracks spread between layers, the composite could suddenly crumble without warning.

Now, MIT engineers have shown they can prevent cracks from spreading between composite’s layers, using an approach they developed called “nanostitching,” in which they deposit chemically grown microscopic forests of carbon nanotubes between composite layers. The tiny, densely packed fibers grip and hold the layers together, like ultrastrong Velcro, preventing the layers from peeling or shearing apart.

In experiments with an advanced composite known as thin-ply carbon fiber laminate, the team demonstrated that layers bonded with nanostitching improved the material’s resistance to cracks by up to 60 percent, compared with composites with conventional polymers. The researchers say the results help to address the main vulnerability in advanced composites.

“Just like phyllo dough flakes apart, composite layers can peel apart because this interlaminar region is the Achilles’ heel of composites,” says Brian Wardle, professor of aeronautics and astronautics at MIT. “We’re showing that nanostitching makes this normally weak region so strong and tough that a crack will not grow there. So, we could expect the next generation of aircraft to have composites held together with this nano-Velcro, to make aircraft safer and have greater longevity.”

Wardle and his colleagues have published their results today in the journal ACS Applied Materials and Interfaces. The study’s first author is former MIT visiting graduate student and postdoc Carolina Furtado, along with Reed Kopp, Xinchen Ni, Carlos Sarrado, Estelle Kalfon-Cohen, and Pedro Camanho.

Forest growth

At MIT, Wardle is director of the necstlab (pronounced “next lab”), where he and his group first developed the concept for nanostitching. The approach involves “growing” a forest of vertically aligned carbon nanotubes — hollow fibers of carbon, each so small that tens of billions of the the nanotubes can stand in an area smaller than a fingernail. To grow the nanotubes, the team used a process of chemical vapor deposition to react various catalysts in an oven, causing carbon to settle onto a surface as tiny, hair-like supports. The supports are eventually removed, leaving behind a densely packed forest of microscopic, vertical rolls of carbon.

The lab has previously shown that the nanotube forests can be grown and adhered to layers of composite material, and that this fiber-reinforced compound improves the material’s overall strength. The researchers had also seen some signs that the fibers can improve a composite’s resistance to cracks between layers.

In their new study, the engineers took a more in-depth look at the between-layer region in composites to test and quantify how nanostitching would improve the region’s resistance to cracks. In particular, the study focused on an advanced composite material known as thin-ply carbon fiber laminates.

“This is an emerging composite technology, where each layer, or ply, is about 50 microns thin, compared to standard composite plies that are 150 microns, which is about the diameter of a human hair. There’s evidence to suggest they are better than standard-thickness composites. And we wanted to see whether there might be synergy between our nanostitching and this thin-ply technology, since it could lead to more resilient aircraft, high-value aerospace structures, and space and military vehicles,” Wardle says.

Velcro grip

The study’s experiments were led by Carolina Furtado, who joined the effort as part of the MIT-Portugal program in 2016, continued the project as a postdoc, and is now a professor at the University of Porto in Portugal, where her research focuses on modeling cracks and damage in advanced composites.

In her tests, Furtado used the group’s techniques of chemical vapor deposition to grow densely packed forests of vertically aligned carbon nanotubes. She also fabricated samples of thin-ply carbon fiber laminates. The resulting advanced composite was about 3 millimeters thick and comprised 60 layers, each made from stiff, horizontal fibers embedded in a polymer sheet.

She transferred and adhered the nanotube forest in between the two middle layers of the composite, then cooked the material in an autoclave to cure. To test crack resistance, the researchers placed a crack on the edge of the composite, right at the start of the region between the two middle layers.

“In fracture testing, we always start with a crack because we want to test whether and how far the crack will spread,” Furtado explains.

The researchers then placed samples of the nanotube-reinforced composite in an experimental setup to test their resilience to “delamination,” or the potential for layers to separate.

“There’s lots of ways you can get precursors to delamination, such as from impacts, like tool drop, bird strike, runway kickup in aircraft, and there could be almost no visible damage, but internally it has a delamination,” Wardle says. “Just like a human, if you’ve got a hairline fracture in a bone, it’s not good. Just because you can’t see it doesn’t mean it’s not impacting you. And damage in composites is hard to inspect.”

To examine nanostitching’s potential to prevent delamination, the team placed their samples in a setup to test three delamination modes, in which a crack could spread through the between-layer region and peel the layers apart or cause them to slide against each other, or do a combination of both. All three of these modes are the most common ways in which conventional composites can internally flake and crumble.

The tests, in which the researchers precisely measured the force required to peel or shear the composite’s layers, revealed that the nanostitched held fast, and the initial crack that the researchers made was unable to spread further between the layers. The nanostitched samples were up to 62 percent tougher and more resistant to cracks, compared with the same advanced composite material that was held together with conventional polymers.

“This is a new composite technology, turbocharged by our nanotubes,” Wardle says.

“The authors have demonsrated that thin plies and nanostitching together have made significant increase in toughness,” says Stephen Tsai, emeritus professor of aeronautics and astronautics at Stanford University. “Composites are degraded by their weak interlaminar strength. Any improvement shown in this work will increase the design allowable, and reduce the weight and cost of composites technology.”

The researchers envision that any vehicle or structure that incorporates conventional composites could be made lighter, tougher, and more resilient with nanostitching.

“You could have selective reinforcement of problematic areas, to reinforce holes or bolted joints, or places where delamination might happen,” Furtado says. “This opens a big window of opportunity.”

When Paula Hammond first arrived on MIT’s campus as a first-year student in the early 1980s, she wasn’t sure if she belonged. In fact, as she told an MIT audience yesterday, she felt like “an imposter.”

However, that feeling didn’t last long, as Hammond began to find support among her fellow students and MIT’s faculty. “Community was really important for me, to feel that I belonged, to feel that I had a place here, and I found people who were willing to embrace me and support me,” she said.

Hammond, a world-renowned chemical engineer who has spent most of her academic career at MIT, made her remarks during the 2023-24 James R. Killian Jr. Faculty Achievement Award lecture.

Established in 1971 to honor MIT’s 10th president, James Killian, the Killian Award recognizes extraordinary professional achievements by an MIT faculty member. Hammond was chosen for this year’s award “not only for her tremendous professional achievements and contributions, but also for her genuine warmth and humanity, her thoughtfulness and effective leadership, and her empathy and ethics,” according to the award citation.

“Professor Hammond is a pioneer in nanotechnology research. With a program that extends from basic science to translational research in medicine and energy, she has introduced new approaches for the design and development of complex drug delivery systems for cancer treatment and noninvasive imaging,” said Mary Fuller, chair of MIT’s faculty and a professor of literature, who presented the award. “As her colleagues, we are delighted to celebrate her career today.”

In January, Hammond began serving as MIT’s vice provost for faculty. Before that, she chaired the Department of Chemical Engineering for eight years, and she was named an Institute Professor in 2021.

A versatile technique

Hammond, who grew up in Detroit, credits her parents with instilling a love of science. Her father was one of very few Black PhDs in biochemistry at the time, while her mother earned a master’s degree in nursing from Howard University and founded the nursing school at Wayne County Community College. “That provided a huge amount of opportunity for women in the area of Detroit, including women of color,” Hammond noted.

After earning her bachelor’s degree from MIT in 1984, Hammond worked as an engineer before returning to the Institute as a graduate student, earning her PhD in 1993. After a two-year postdoc at Harvard University, she returned to join the MIT faculty in 1995.

At the heart of Hammond’s research is a technique she developed to create thin films that can essentially “shrink-wrap” nanoparticles. By tuning the chemical composition of these films, the particles can be customized to deliver drugs or nucleic acids and to target specific cells in the body, including cancer cells.

To make these films, Hammond begins by layering positively charged polymers onto a negatively charged surface. Then, more layers can be added, alternating positively and negatively charged polymers. Each of these layers may contain drugs or other useful molecules, such as DNA or RNA. Some of these films contain hundreds of layers, others just one, making them useful for a wide range of applications.

“What’s nice about the layer-by-layer process is I can choose a group of degradable polymers that are nicely biocompatible, and I can alternate them with our drug materials. This means that I can build up thin film layers that contain different drugs at different points within the film,” Hammond said. “Then, when the film degrades, it can release those drugs in reverse order. This is enabling us to create complex, multidrug films, using a simple water-based technique.”

Hammond described how these layer-by-layer films can be used to promote bone growth, in an application that could help people born with congenital bone defects or people who experience traumatic injuries.

For that use, her lab has created films with layers of two proteins. One of these, BMP-2, is a protein that interacts with adult stem cells and induces them to differentiate into bone cells, generating new bone. The second is a growth factor called VEGF, which stimulates the growth of new blood vessels that help bone to regenerate. These layers are applied to a very thin tissue scaffold that can be implanted at the injury site.

Hammond and her students designed the coating so that once implanted, it would release VEGF early, over a week or so, and continue releasing BMP-2 for up to 40 days. In a study of mice, they found that this tissue scaffold stimulated the growth of new bone that was nearly indistinguishable from natural bone.

Targeting cancer

As a member of MIT’s Koch Institute for Integrative Cancer Research, Hammond has also developed layer-by-layer coatings that can improve the performance of nanoparticles used for cancer drug delivery, such as liposomes or nanoparticles made from a polymer called PLGA.

“We have a broad range of drug carriers that we can wrap this way. I think of them like a gobstopper, where there are all those different layers of candy and they dissolve one at a time,” Hammond said.

Using this approach, Hammond has created particles that can deliver a one-two punch to cancer cells. First, the particles release a dose of a nucleic acid such as short interfering RNA (siRNA), which can turn off a cancerous gene, or microRNA, which can activate tumor suppressor genes. Then, the particles release a chemotherapy drug such as cisplatin, to which the cells are now more vulnerable.

The particles also include a negatively charged outer “stealth layer” that protects them from being broken down in the bloodstream before they can reach their targets. This outer layer can also be modified to help the particles get taken up by cancer cells, by incorporating molecules that bind to proteins that are abundant on tumor cells.

In more recent work, Hammond has begun developing nanoparticles that can target ovarian cancer and help prevent recurrence of the disease after chemotherapy. In about 70 percent of ovarian cancer patients, the first round of treatment is highly effective, but tumors recur in about 85 percent of those cases, and these new tumors are usually highly drug resistant.

By altering the type of coating applied to drug-delivering nanoparticles, Hammond has found that the particles can be designed to either get inside tumor cells or stick to their surfaces. Using particles that stick to the cells, she has designed a treatment that could help to jumpstart a patient’s immune response to any recurrent tumor cells.

“With ovarian cancer, very few immune cells exist in that space, and because they don’t have a lot of immune cells present, it’s very difficult to rev up an immune response,” she said. “However, if we can deliver a molecule to neighboring cells, those few that are present, and get them revved up, then we might be able to do something.”

To that end, she designed nanoparticles that deliver IL-12, a cytokine that stimulates nearby T cells to spring into action and begin attacking tumor cells. In a study of mice, she found that this treatment induced a long-term memory T-cell response that prevented recurrence of ovarian cancer.

Hammond closed her lecture by describing the impact that the Institute has had on her throughout her career.

“It’s been a transformative experience,” she said. “I really think of this place as special because it brings people together and enables us to do things together that we couldn’t do alone. And it is that support we get from our friends, our colleagues, and our students that really makes things possible.”

Globally, computation is booming at an unprecedented rate, fueled by the boons of artificial intelligence. With this, the staggering energy demand of the world’s computing infrastructure has become a major concern, and the development of computing devices that are far more energy-efficient is a leading challenge for the scientific community. 

Use of magnetic materials to build computing devices like memories and processors has emerged as a promising avenue for creating “beyond-CMOS” computers, which would use far less energy compared to traditional computers. Magnetization switching in magnets can be used in computation the same way that a transistor switches from open or closed to represent the 0s and 1s of binary code. 

While much of the research along this direction has focused on using bulk magnetic materials, a new class of magnetic materials — called two-dimensional van der Waals magnets — provides superior properties that can improve the scalability and energy efficiency of magnetic devices to make them commercially viable. 

Although the benefits of shifting to 2D magnetic materials are evident, their practical induction into computers has been hindered by some fundamental challenges. Until recently, 2D magnetic materials could operate only at very low temperatures, much like superconductors. So bringing their operating temperatures above room temperature has remained a primary goal. Additionally, for use in computers, it is important that they can be controlled electrically, without the need for magnetic fields. Bridging this fundamental gap, where 2D magnetic materials can be electrically switched above room temperature without any magnetic fields, could potentially catapult the translation of 2D magnets into the next generation of “green” computers.

A team of MIT researchers has now achieved this critical milestone by designing a “van der Waals atomically layered heterostructure” device where a 2D van der Waals magnet, iron gallium telluride, is interfaced with another 2D material, tungsten ditelluride. In an open-access paper published March 15 in Science Advances, the team shows that the magnet can be toggled between the 0 and 1 states simply by applying pulses of electrical current across their two-layer device. 

“Our device enables robust magnetization switching without the need for an external magnetic field, opening up unprecedented opportunities for ultra-low power and environmentally sustainable computing technology for big data and AI,” says lead author Deblina Sarkar, the AT&T Career Development Assistant Professor at the MIT Media Lab and Center for Neurobiological Engineering, and head of the Nano-Cybernetic Biotrek research group. “Moreover, the atomically layered structure of our device provides unique capabilities including improved interface and possibilities of gate voltage tunability, as well as flexible and transparent spintronic technologies.”

Sarkar is joined on the paper by first author Shivam Kajale, a graduate student in Sarkar’s research group at the Media Lab; Thanh Nguyen, a graduate student in the Department of Nuclear Science and Engineering (NSE); Nguyen Tuan Hung, an MIT visiting scholar in NSE and an assistant professor at Tohoku University in Japan; and Mingda Li, associate professor of NSE.

Breaking the mirror symmetries 

When electric current flows through heavy metals like platinum or tantalum, the electrons get segregated in the materials based on their spin component, a phenomenon called the spin Hall effect, says Kajale. The way this segregation happens depends on the material, and particularly its symmetries.

“The conversion of electric current to spin currents in heavy metals lies at the heart of controlling magnets electrically,” Kajale notes. “The microscopic structure of conventionally used materials, like platinum, have a kind of mirror symmetry, which restricts the spin currents only to in-plane spin polarization.”

Kajale explains that two mirror symmetries must be broken to produce an “out-of-plane” spin component that can be transferred to a magnetic layer to induce field-free switching. “Electrical current can 'break' the mirror symmetry along one plane in platinum, but its crystal structure prevents the mirror symmetry from being broken in a second plane.”

In their earlier experiments, the researchers used a small magnetic field to break the second mirror plane. To get rid of the need for a magnetic nudge, Kajale and Sarkar and colleagues looked instead for a material with a structure that could break the second mirror plane without outside help. This led them to another 2D material, tungsten ditelluride. The tungsten ditelluride that the researchers used has an orthorhombic crystal structure. The material itself has one broken mirror plane. Thus, by applying current along its low-symmetry axis (parallel to the broken mirror plane), the resulting spin current has an out-of-plane spin component that can directly induce switching in the ultra-thin magnet interfaced with the tungsten ditelluride. 

“Because it's also a 2D van der Waals material, it can also ensure that when we stack the two materials together, we get pristine interfaces and a good flow of electron spins between the materials,” says Kajale. 

Becoming more energy-efficient 

Computer memory and processors built from magnetic materials use less energy than traditional silicon-based devices. And the van der Waals magnets can offer higher energy efficiency and better scalability compared to bulk magnetic material, the researchers note. 

The electrical current density used for switching the magnet translates to how much energy is dissipated during switching. A lower density means a much more energy-efficient material. “The new design has one of the lowest current densities in van der Waals magnetic materials,” Kajale says. “This new design has an order of magnitude lower in terms of the switching current required in bulk materials. This translates to something like two orders of magnitude improvement in energy efficiency.”

The research team is now looking at similar low-symmetry van der Waals materials to see if they can reduce current density even further. They are also hoping to collaborate with other researchers to find ways to manufacture the 2D magnetic switch devices at commercial scale. 

This work was carried out, in part, using the facilities at MIT.nano. It was funded by the Media Lab, the U.S. National Science Foundation, and the U.S. Department of Energy.

Mo Mirvakili PhD ’17 was in the middle of an experiment as a postdoc at MIT when the Covid-19 pandemic hit. Grappling with restricted access to laboratory facilities, he decided to transform his bathroom into a makeshift lab. Arranging a piece of plywood over the bathtub to support power sources and measurement devices, he conducted a study that was later published in Science Robotics, one of the top journals in the field.

The adversity made for a good story, but the truth is that it didn’t take a global pandemic to force Mirvakili to build the equipment he needed to run his experiments. Even when working in some of the most well-funded labs in the world, he needed to piece together tools to bring his experiments to life.

“My journey reflects a broader truth: With determination and resourcefulness, many of us can achieve remarkable things,” he says. “There are so many people who don't have access to labs yet have great ideas. We need to make it easier for them to bring their experiments to life.”

That’s the idea behind Seron Electronics, a company Mirvakili founded to democratize scientific experimentation. Seron develops scientific equipment that precisely sources and measures power, characterizes materials, and integrates data into a customizable software platform.

By making sophisticated experiments more accessible, Seron aims to spur a new wave of innovation across fields as diverse as microelectronics, clean energy, optics, and biomedicine.

“Our goal is to become one of the leaders in providing accurate and affordable solutions for researchers,” Mirvakili says. “This vision extends beyond academia to include companies, governments, nonprofits, and even high school students. With Seron’s devices, anyone can conduct high-quality experiments, regardless of their background or resources.”

Feeling the need for constant power

Mirvakili earned his bachelor's and master's degrees in electrical engineering, followed by a PhD in mechanical engineering under MIT Professor Ian Hunter, which involved developing a class of high-performance thermal artificial muscles, including nylon artificial muscles. During that time, Mirvakili needed to precisely control the amount of energy that flowed through his experimental setups, but he couldn't find anything online that would solve his problem.

“I had access to all sorts of high-end equipment in our lab and the department,” Mirvakili recalls. “It’s all the latest, state-of-the-art stuff. But I had to bundle all these outside tools together for my work.”

After completing his PhD, Mirvakili joined Institute Professor Bob Langer’s lab as a postdoc, where he worked directly with Langer on a totally different problem in biomedical engineering. In Langer's famously prolific lab, he saw researchers struggling to control temperatures at the microscale for a device that was encapsulating drugs.

Mirvakili realized the researchers were ultimately struggling with the same set of problems: the need to precisely control electric current, voltage, and power. Those are also problems Mirvakili has seen in his more recent research into energy storage and solar cells. After speaking with researchers at conferences from around the world to confirm the need was widespread, he started Seron Electronics.

Seron calls the first version of its products the SE Programmable Power Platforms. The platforms allow users to source and measure precisely defined quantities of electrical voltage, current, power, and charge through a desktop application with minimal signal interference, or noise.

The equipment can be used to study things like semiconductor devices, actuators, and energy storage devices, or to precisely charge batteries without damaging their performance.

The equipment can also be used to study material performance because it can measure how materials react to precise electrical stimulation at a high resolution, and for quality control because it can test chips and flag problems.

The use cases are varied, but Seron’s overarching goal is to enable more innovation faster.

“Because our system is so intuitive, you reduce the time to get results,” Mirvakili says. “You can set it up in less than five minutes. It’s plug-and-play. Researchers tell us it speeds things up a lot.”

New frontiers

In a recent paper Mirvakili coauthored with MIT research affiliate Ehsan Haghighat, Seron’s equipment provided constant power to a thermal artificial muscle that integrated machine learning to give it a sort of muscle memory. In another study Mirvakili was not involved in, a nonprofit research organization used Seron’s equipment to identify a new, sustainable sensor material they are in the process of commercializing.

Many uses of the machines have come as a surprise to Seron’s team, and they expect to see a new wave of applications when they release a cheaper, portable version of Seron’s machines this summer. That could include the development of new bedside monitors for patients that can detect diseases, or remote sensors for field work.

Mirvakili thinks part of the beauty of Seron’s devices is that people in the company don’t have to dream up the experiments themselves. Instead, they can focus on providing powerful scientific tools and let the research community decide on the best ways to use them.

“Because of the size and the cost of this new device, it will really open up the possibilities for researchers," Mirvakili says. “Anyone who has a good idea should be able to turn that idea into reality with our equipment and solutions. In my mind, the applications are really unimaginable and endless.”

Neutrons are subatomic particles that have no electric charge, unlike protons and electrons. That means that while the electromagnetic force is responsible for most of the interactions between radiation and materials, neutrons are essentially immune to that force.

Instead, neutrons are held together inside an atom’s nucleus solely by something called the strong force, one of the four fundamental forces of nature. As its name implies, the force is indeed very strong, but only at very close range — it drops off so rapidly as to be negligible beyond 1/10,000 the size of an atom. But now, researchers at MIT have found that neutrons can actually be made to cling to particles called quantum dots, which are made up of tens of thousands of atomic nuclei, held there just by the strong force.

The new finding may lead to useful new tools for probing the basic properties of materials at the quantum level, including those arising from the strong force, as well as exploring new kinds of quantum information processing devices. The work is reported this week in the journal ACS Nano, in a paper by MIT graduate students Hao Tang and Guoqing Wang and MIT professors Ju Li and Paola Cappellaro of the Department of Nuclear Science and Engineering.

Neutrons are widely used to probe material properties using a method called neutron scattering, in which a beam of neutrons is focused on a sample, and the neutrons that bounce off the material’s atoms can be detected to reveal the material’s internal structure and dynamics.

But until this new work, nobody thought that these neutrons might actually stick to the materials they were probing. “The fact that [the neutrons] can be trapped by the materials, nobody seems to know about that,” says Li, who is also a professor of materials science and engineering. “We were surprised that this exists, and that nobody had talked about it before, among the experts we had checked with,” he says.

The reason this new finding is so surprising, Li explains, is because neutrons don’t interact with electromagnetic forces. Of the four fundamental forces, gravity and the weak force “are generally not important for materials,” he says. “Pretty much everything is electromagnetic interaction, but in this case, since the neutron doesn’t have a charge, the interaction here is through the strong interaction, and we know that is very short-range. It is effective at a range of 10 to the minus 15 power,” or one quadrillionth, of a meter.

“It’s very small, but it’s very intense,” he says of this force that holds the nuclei of atoms together. “But what’s interesting is we’ve got these many thousands of nuclei in this neutronic quantum dot, and that’s able to stabilize these bound states, which have much more diffuse wavefunctions at tens of nanometers [billionths of a meter].  These neutronic bound states in a quantum dot are actually quite akin to Thomson’s plum pudding model of an atom, after his discovery of the electron.”

It was so unexpected, Li calls it “a pretty crazy solution to a quantum mechanical problem.” The team calls the newly discovered state an artificial “neutronic molecule.”

These neutronic molecules are made from quantum dots, which are tiny crystalline particles, collections of atoms so small that their properties are governed more by the exact size and shape of the particles than by their composition. The discovery and controlled production of quantum dots were the subject of the 2023 Nobel Prize in Chemistry, awarded to MIT Professor Moungi Bawendi and two others.

“In conventional quantum dots, an electron is trapped by the electromagnetic potential created by a macroscopic number of atoms, thus its wavefunction extends to about 10 nanometers, much larger than a typical atomic radius,” says Cappellaro. “Similarly, in these nucleonic quantum dots, a single neutron can be trapped by a nanocrystal, with a size well beyond the range of the nuclear force, and display similar quantized energies.” While these energy jumps give quantum dots their colors, the neutronic quantum dots could be used for storing quantum information.

This work is based on theoretical calculations and computational simulations. “We did it analytically in two different ways, and eventually also verified it numerically,” Li says. Although the effect had never been described before, he says, in principle there’s no reason it couldn’t have been found much sooner: “Conceptually, people should have already thought about it,” he says, but as far as the team has been able to determine, nobody did.

Part of the difficulty in doing the computations is the very different scales involved: The binding energy of a neutron to the quantum dots they were attaching to is about one-trillionth that of previously known conditions where the neutron is bound to a small group of nucleons. For this work, the team used an analytical tool called Green’s function to demonstrate that the strong force was sufficient to capture neutrons with a quantum dot with a minimum radius of 13 nanometers.

Then, the researchers did detailed simulations of specific cases, such as the use of a lithium hydride nanocrystal, a material being studied as a possible storage medium for hydrogen. They showed that the binding energy of the neutrons to the nanocrystal is dependent on the exact dimensions and shape of the crystal, as well as the nuclear spin polarizations of the nuclei compared to that of the neutron. They also calculated similar effects for thin films and wires of the material as opposed to particles.

But Li says that actually creating such neutronic molecules in the lab, which among other things requires specialized equipment to maintain temperatures in the range of a few thousandths of a Kelvin above absolute zero, is something that other researchers with the appropriate expertise will have to undertake.

Li notes that “artificial atoms” made up of assemblages of atoms that share properties and can behave in many ways like a single atom have been used to probe many properties of real atoms. Similarly, he says, these artificial molecules provide “an interesting model system” that might be used to study “interesting quantum mechanical problems that one can think about,” such as whether these neutronic molecules will have a shell structure that mimics the electron shell structure of atoms.

“One possible application,” he says, “is maybe we can precisely control the neutron state. By changing the way the quantum dot oscillates, maybe we can shoot the neutron off in a particular direction.” Neutrons are powerful tools for such things as triggering both fission and fusion reactions, but so far it has been difficult to control individual neutrons. These new bound states could provide much greater degrees of control over individual neutrons, which could play a role in the development of new quantum information systems, he says.

“One idea is to use it to manipulate the neutron, and then the neutron will be able to affect other nuclear spins,” Li says. In that sense, he says, the neutronic molecule could serve as a mediator between the nuclear spins of separate nuclei — and this nuclear spin is a property that is already being used as a basic storage unit, or qubit, in developing quantum computer systems.

“The nuclear spin is like a stationary qubit, and the neutron is like a flying qubit,” he says. “That’s one potential application.” He adds that this is “quite different from electromagnetics-based quantum information processing, which is so far the dominant paradigm. So, regardless of whether it’s superconducting qubits or it’s trapped ions or nitrogen vacancy centers, most of these are based on electromagnetic interactions.” In this new system, instead, “we have neutrons and nuclear spin. We’re just starting to explore what we can do with it now.”

Another possible application, he says, is for a kind of imaging, using neutral activation analysis. “Neutron imaging complements X-ray imaging because neutrons are much more strongly interacting with light elements,” Li says. It can also be used for materials analysis, which can provide information not only about elemental composition but even about the different isotopes of those elements. “A lot of the chemical imaging and spectroscopy doesn’t tell us about the isotopes,” whereas the neutron-based method could do so, he says.

The research was supported by the U.S. Office of Naval Research.

Without a map, it can be just about impossible to know not just where you are, but where you’re going, and that’s especially true when it comes to materials properties.

For decades, scientists have understood that while bulk materials behave in certain ways, those rules can break down for materials at the micro- and nano-scales, and often in surprising ways. One of those surprises was the finding that, for some materials, applying even modest strains — a concept known as elastic strain engineering — on materials can dramatically improve certain properties, provided those strains stay elastic and do not relax away by plasticity, fracture, or phase transformations. Micro- and nano-scale materials are especially good at holding applied strains in the elastic form.

Precisely how to apply those elastic strains (or equivalently, residual stress) to achieve certain material properties, however, had been less clear — until recently.

Using a combination of first principles calculations and machine learning, a team of MIT researchers has developed the first-ever map of how to tune crystalline materials to produce specific thermal and electronic properties.

Led by Ju Li, the Battelle Energy Alliance Professor in Nuclear Engineering and professor of materials science and engineering, the team described a framework for understanding precisely how changing the elastic strains on a material can fine-tune properties like thermal and electrical conductivity. The work is described in an open-access paper published in PNAS.

“For the first time, by using machine learning, we’ve been able to delineate the complete six-dimensional boundary of ideal strength, which is the upper limit to elastic strain engineering, and create a map for these electronic and phononic properties,” Li says. “We can now use this approach to explore many other materials. Traditionally, people create new materials by changing the chemistry.”

“For example, with a ternary alloy, you can change the percentage of two elements, so you have two degrees of freedom,” he continues. “What we’ve shown is that diamond, with just one element, is equivalent to a six-component alloy, because you have six degrees of elastic strain freedom you can tune independently.”

Small strains, big material benefits

The paper builds on a foundation laid as far back as the 1980s, when researchers first discovered that the performance of semiconductor materials doubled when a small — just 1 percent — elastic strain was applied to the material.

While that discovery was quickly commercialized by the semiconductor industry and today is used to increase the performance of microchips in everything from laptops to cellphones, that level of strain is very small compared to what we can achieve now, says Subra Suresh, the Vannevar Bush Professor of Engineering Emeritus.

In a 2018 Science paper, Suresh, Dao, and colleagues demonstrated that 1 percent strain was just the tip of the iceberg.

As part of a 2018 study, Suresh and colleagues demonstrated for the first time that diamond nanoneedles could withstand elastic strains of as much as 9 percent and still return to their original state. Later on, several groups independently confirmed that microscale diamond can indeed elastically deform by approximately 7 percent in tension reversibly.

“Once we showed we could bend nanoscale diamonds and create strains on the order of 9 or 10 percent, the question was, what do you do with it,” Suresh says. “It turns out diamond is a very good semiconductor material … and one of our questions was, if we can mechanically strain diamond, can we reduce the band gap from 5.6 electron-volts to two or three? Or can we get it all the way down to zero, where it begins to conduct like a metal?”

To answer those questions, the team first turned to machine learning in an effort to get a more precise picture of exactly how strain altered material properties.

“Strain is a big space,” Li explains. “You can have tensile strain, you can have shear strain in multiple directions, so it’s a six-dimensional space, and the phonon band is three-dimensional, so in total there are nine tunable parameters. So, we’re using machine learning, for the first time, to create a complete map for navigating the electronic and phononic properties and identify the boundaries.”

Armed with that map, the team subsequently demonstrated how strain could be used to dramatically alter diamond’s semiconductor properties.

“Diamond is like the Mt. Everest of electronic materials,” Li says, “because it has very high thermal conductivity, very high dielectric breakdown strengths, a very big carrier mobility. What we have shown is we can controllably squish Mt. Everest down … so we show that by strain engineering you can either improve diamond’s thermal conductivity by a factor of two, or make it much worse by a factor of 20.”

New map, new applications

Going forward, the findings could be used to explore a host of exotic material properties, Li says, from dramatically reduced thermal conductivity to superconductivity.

“Experimentally, these properties are already accessible with nanoneedles and even microbridges,” he says. “And we have seen exotic properties, like reducing diamond’s (thermal conductivity) to only a few hundred watts per meter-Kelvin. Recently, people have shown that you can produce room-temperature superconductors with hydrides if you squeeze them to a few hundred gigapascals, so we have found all kinds of exotic behavior once we have the map.”

The results could also influence the design of next-generation computer chips capable of running much faster and cooler than today’s processors, as well as quantum sensors and communication devices. As the semiconductor manufacturing industry moves to denser and denser architectures, Suresh says the ability to tune a material’s thermal conductivity will be particularly important for heat dissipation.

While the paper could inform the design of future generations of microchips, Zhe Shi, a postdoc in Li’s lab and first author of the paper, says more work will be needed before those chips find their way into the average laptop or cellphone.

“We know that 1 percent strain can give you an order of magnitude increase in the clock speed of your CPU,” Shi says. “There are a lot of manufacturing and device problems that need to be solved in order for this to become realistic, but I think it’s definitely a great start. It’s an exciting beginning to what could lead to significant strides in technology.”

This work was supported with funding from the Defense Threat Reduction Agency, an NSF Graduate Research Fellowship, the Nanyang Technological University School of Biological Sciences, the National Science Foundation (NSF), the MIT Vannevar Bush Professorship, and a Nanyang Technological University Distinguished University Professorship.

VIAVI Solutions, a global provider of communications test and measurement and optical technologies, has joined the MIT.nano Consortium.

With roots going back to 1923 as Wandell and Goltermann and to 1948 as Optical Coating Laboratory Inc., VIAVI is a global enterprise supporting innovation in communication networks, hyperscale and enterprise data centers, consumer electronics, automotive sensing, mission-critical avionics, aerospace, and anti-counterfeiting technologies.

“VIAVI is an exciting new member of the MIT.nano Consortium. The company’s innovations overlap with MIT’s research interests in a variety of applications — electronics, 3D sensing, optics, data analysis, artificial intelligence, and more,” says Vladimir Bulović, the founding faculty director of MIT.nano and the Fariborz Maseeh (1990) Professor of Emerging Technologies. “VIAVI’s awareness of industry needs will make them a valuable collaborator as we at MIT.nano work to develop new technologies in the lab that can successfully transition to the real world.”

With over 3,600 employees in 22 countries, VIAVI is poised to contribute global insights to the MIT.nano Consortium and MIT research community.

“VIAVI is delighted to be part of the extraordinary MIT.nano ecosystem,” says Oleg Khaykin, president and CEO of VIAVI. “MIT.nano occupies a unique position at the intersection of academia, industry, and government. We look forward to collaborating with the organization and its stakeholders focused on innovation in materials and processes that will enable the photonics applications of the future.”

The MIT.nano Consortium is a platform for academia-industry collaboration centered around research and innovation emerging from nanoscale science and engineering at MIT. Through activities that include quarterly industry consortium meetings, VIAVI will gain insight into the work of MIT.nano’s community of users and provide advice to help guide and advance nanoscale innovations at MIT alongside the 11 other consortium companies:

• Analog Devices
• Edwards
• Fujikura
• IBM Research
• Lam Research
• Lockheed Martin
• NC
• NEC
• Raith
• Shell
• UpNano

MIT.nano continues to welcome new companies as sustaining members. For more details, visit the MIT.nano Consortium page.

“I want to tell you that you don’t have to be just one thing,” said Katie Eckermann ’03, MEng ’04, director of business development at Advanced Micro Devices (AMD) at a networking event for students considering careers in hard technologies. “There is a huge wealth of different jobs and roles within the semiconductor industry.”

Eckermann was one of two keynote speakers at the Design the Solution conference, presented by the Global Semiconductor Alliance (GSA) Women’s Leadership Initiative, and co-sponsored by MIT.nano. Following the speaking portion of the event, attendees were invited to meet with representatives from AMD, Analog Devices, Applied Materials, Arm, Cadence Design Systems, Cisco Systems, Intel, Marvell, Micron Technology, Samsung, Synopsys, and TSMC. This annual February event was one in a series organized by the GSA Women’s Leadership Initiative and hosted at universities across the country to highlight the global impact of a career in semiconductors and recruit more women into the hard-tech ecosystem.

Eckermann was joined by John Wuu ’96, MEng ’97, senior fellow design engineer at AMD. Together, the two highlighted some of the key trends and most significant challenges of the semiconductor industry, as well as shared their career paths and advice.

Wuu highlighted the tremendous increase in computing performance in recent years, illustrated in 2022 by Hewlett Packard’s Frontier computer — calculating complex problems much faster than several other supercomputers combined. While supercomputer performance has doubled every 1.2 years over the last 30 years, power efficiency has doubled only every 2.2 years — thus underscoring a clear need to continue the pace of performance sustainably and responsibly.

“These performance improvements are not about trying to break records just for the sake of breaking records,” said Wuu. “The demand for computing is very high and insatiable, and the improvements in performance that we’re getting are being used to solve some of humanity’s most challenging and important problems — from space exploration to climate change, and more.”

Both Wuu and Eckermann encouraged students pursuing careers in semiconductors to focus on learning and stretching themselves, taking risks, and growing their network. They also emphasized the many different skill sets needed in the semiconductor industry and the common problems that often exist across different market segments.

“One of the most valuable things about MIT is that it doesn’t teach you how to recite formulas or to memorize facts, it teaches you a framework on how to think,” said Eckermann. “And when it comes down to engineering, it’s all about solving complex problems.”

Following the keynote, Deb Dyson, senior staff engineering manager at Marvell, moderated a panel discussion featuring Rose Castanares, senior vice president for business management at TSMC North America; Kate Shamberger, field technical director for the Americas at Analog Devices; and Thy Tran, vice president of global frontend procurement at Micron Technology.

The panelists described their own individual and diverse career journeys, also emphasizing the tremendous amount and variety of opportunities currently available in semiconductors.

“Everywhere you look [in the semiconductor industry], it is the epicenter of all the intersectionality of the disciplines,” said Tran. “It’s the pure sciences, the math, the engineering, application-based, theory-based — I can’t believe I got so lucky to be in this arena.”

Some key themes of the panel discussion included the importance of teamwork and understanding the people you’re working with, the development of leadership styles, and trying out different types of roles within the industry. All speakers encouraged students to identify what they like to do most and think broadly and flexibly about how they can apply their skills and interests — and, above all, to always be learning and gaining a breadth of knowledge.

“It’s important to be continually learning — not just in your field, but also adjunct to your field,” said Castanares. “It’s not about trying to prove that you’re the smartest person in the room, but the most curious person in the room — and then apply and share that knowledge.”

MIT has a rich history of productive collaboration between the arts and the sciences, anchored by the conviction that these two conventionally opposed ways of thinking can form a deeply generative symbiosis that serves to advance and humanize new technologies. 

This ethos was made tangible when the Bauhaus artist and educator György Kepes established the MIT Center for Advanced Visual Studies (CAVS) within the Department of Architecture in 1967. CAVS has since evolved into the Art, Culture, and Technology (ACT) program, which fosters close links to multiple other programs, centers, and labs at MIT. Class 4.373/4.374 (Creating Art, Thinking Science), open to undergraduates and master’s students of all disciplines as well as certain students from the Harvard Graduate School of Design (GSD), is one of the program’s most innovative offerings, proposing a model for how the relationship between art and science might play out at a time of exponential technological growth. 

Now in its third year, the class is supported by an Interdisciplinary Class Development Grant from the MIT Center for Art, Science and Technology (CAST) and draws upon the unparalleled resources of MIT.nano; an artist’s high-tech toolbox for investigating the hidden structures and beauty of our material universe.

High ambitions and critical thinking

The class was initiated by Tobias Putrih, lecturer in ACT, and is taught with the assistance of Ardalan SadeghiKivi MArch ’23, and Aubrie James SM ’24. Central to the success of the class has been the collaboration with co-instructor Vladimir Bulović, the founding director of MIT.nano and Fariborz Maseeh Chair in Emerging Technology, who has positioned the facility as an open-access resource for the campus at large — including MIT’s community of artists. “Creating Art, Thinking Science” unfolds the 100,000 square feet of cleanroom and lab space within the Lisa T. Su Building, inviting participating students to take advantage of cutting-edge equipment for nanoscale visualization and fabrication; in the hands of artists, devices for discovering nanostructures and manipulating atoms become tools for rendering the invisible visible and deconstructing the dynamics of perception itself. 

The expansive goals of the class are tempered by an in-built criticality. “ACT has a unique position as an art program nested within a huge scientific institute — and the challenges of that partnership should not be underestimated,” reflects Putrih. “Science and art are wholly different knowledge systems with distinct historical perspectives. So, how do we communicate? How do we locate that middle ground, that third space?”

An evolving answer, tested and developed throughout the partnership between ACT and MIT.nano, involves a combination of attentive mentorship and sharing of artistic ideas, combined with access to advanced technological resources and hands-on practical training. 

“MIT.nano currently accommodates more than 1,200 individuals to do their work, across 250 different research groups,” says Bulović. “The fact that we count artists among those is a matter of pride for us. We’ve found that the work of our scientists and technologists is enhanced by having access to the language of art as a form of expression — equally, the way that artists express themselves can be stretched beyond what could previously be imagined, simply by having access to the tools and instruments at MIT.nano.”

A playground for experimentation

True to the spirit of the scientific method and artistic iteration, the class is envisioned as a work in progress — a series of propositions and prototypes for how dialogue between scientists and artists might work in practice. The outcomes of those experiments can now be seen installed in the first and second floor galleries at MIT.nano. As part of the facility’s five-year anniversary celebration, the class premiered an exhibition showcasing works created during previous years of “Creating Art, Thinking Science.” 

Visitors to the exhibition, “zero.zerozerozerozerozerozerozerozeroone” (named for the numerical notation for one nanometer), will encounter artworks ranging from a minimalist silicon wafer produced with two-photon polymerization (2PP) technology (“Obscured Invisibility,” 2021, Hyun Woo Park), to traces of an attempt to make vegetable soup in the cleanroom using equipment such as a cryostat, a fluorescing microscope, and a Micro-CT scanner (“May I Please Make You Some Soup?,” 2022, Simone Lasser). 

These works set a precedent for the artworks produced during the fall 2023 iteration of the class. For Ryan Yang, in his senior year studying electrical engineering and computer science at MIT, the chance to engage in open discussion and experimental making has been a rare opportunity to “try something that might not work.” His project explores the possibilities of translating traditional block printing techniques to micron-scale 3D-printing in the MIT.nano labs.

Yang has taken advantage of the arts curriculum at MIT at an early stage in his academic career as an engineer; meanwhile, Ameen Kaleem started out as a filmmaker in New Delhi and is now pursuing a master’s degree in design engineering at Harvard GSD, cross-registered at MIT. 

Kaleem’s project models the process of abiogenesis (the evolution of living organisms from inorganic or inanimate substances) by bringing living moss into the MIT.nano cleanroom facilities to be examined at an atomic scale. “I was interested in the idea that, as a human being in the cleanroom, you are both the most sanitized version of yourself and the dirtiest thing in that space,” she reflects. “Drawing attention to the presence of organic life in the cleanroom is comparable to bringing art into spaces where it might not otherwise exist — a way of humanizing scientific and technological endeavors.”

Consciousness, immersion, and innovation

The students draw upon the legacies of landmark art-science initiatives — including international exhibitions such as “Cybernetic Serendipity” (London ICA, 1968), the “New Tendencies” series (Zagreb, 1961-73), and “Laboratorium” (Antwerp, 1999) — and take inspiration from the instructors’ own creative investigations of the inner workings of different knowledge systems. “In contemporary life, and at MIT in particular, we’re immersed in technology,” says Putrih. “It’s the nature of art to reveal that to us, so that we might see the implications of what we are producing and its potential impact.”

By fostering a mindset of imagination and criticality, combined with building the technical skills to address practical problems, “Creating Art, Thinking Science” seeks to create the conditions for a more expansive version of technological optimism; a culture of innovation in which social and environmental responsibility are seen as productive parameters for enriched creativity. The ripple effects of the class might be years in the making, but as Bulović observes while navigating the exhibition at MIT.nano, “The joy of the collaboration can be felt in the artworks.”

Undergrads, take note: The lessons you learn in those intro classes could be the key to making your next big discovery. At least, that’s been the case for MIT’s Jeehwan Kim.

A recently tenured faculty member in MIT’s departments of Mechanical Engineering and Materials Science and Engineering, Kim has made numerous discoveries about the nanostructure of materials and is funneling them directly into the advancement of next-generation electronics.

His research aims to push electronics past the inherent limits of silicon — a material that has reliably powered transistors and most other electronic elements but is reaching a performance limit as more computing power is packed into ever smaller devices.

Today, Kim and his students at MIT are exploring materials, devices, and systems that could take over where silicon leaves off. Kim is applying his insights to design next-generation devices, including low-power, high-performance transistors and memory devices, artificial intelligence chips, ultra-high-definition micro-LED displays, and flexible electronic “skin.” Ultimately, he envisions such beyond-silicon devices could be built into supercomputers small enough to fit in your pocket.

The innovations that have come out of his research are recorded in more than 200 issued U.S. patents and 70 research papers — an extensive list that he and his students continue to grow.

Kim credits many of his breakthroughs to the fundamentals he learned in his university days. In fact, he has carried his college textbooks and notes with him with every move. Today, he keeps the undergraduate notes — written in a light and meticulous graphite and ink — on a shelf nearest to his MIT desk, close at hand. He references them in his own class lectures and presentations, and when brainstorming research solutions.

“These textbooks are all in my brain now,” Kim says. “I’ve learned that if you completely understand the fundamentals, you can solve any problem.”

Fundamental shift

Kim wasn’t always a model student. Growing up in Seoul, South Korea, he was fixed on a musical career. He had a passion for singing and was bored by most other high school subjects.

“It was very monotonic,” Kim recalls. “My motivation for high school subjects was very low.”

After graduating high school, he enrolled in a materials science program at Hongik University, where he was lucky to met professors who had graduated from MIT and who later motivated him to study in the United States. But, Kim spent his first year there trying to make it as a musician. He wrote and sang songs that he recorded and sent to promoters, and went to multiple auditions. But after a year, he was faced with no call-backs, and a hard question.

“What should I do? It was a crisis to me,” Kim says.

In his second year, he decided to give materials science a go. When he sat in on his first class, he was surprised to find that the subject — the structure and behavior of materials at the atomic scale — made him want to learn more.

“My first year, my GPA was almost zero because I didn’t attend class, and was going to be kicked out,” Kim says. “Then from my second year on, I really loved every single subject in materials science. People who saw me in the library were surprised: ‘What are you doing here, without a guitar?’ I must have read these textbooks more than 10 times, and felt I really understood everything fundamental.”

Back to basics

He took this newfound passion to Seoul National University, where he enrolled in the materials science master’s program and learned to apply the ideas he absorbed to hands-on research problems. Metallurgy was a dominant field at the time, and Kim was assigned to experiment with high-temperature alloys — mixing and melting metallic powders to create materials that could be used in high-performance engines.

After completing his master’s, Kim wanted to continue with a PhD, overseas. But to do so, he first had to serve in the military. He spent the next two and a half years in the Korean air force, helping to maintain and refuel aircraft, and inventory their parts. All the while, he prepared applications to graduate schools abroad.

In 2003, after completing his service, he headed overseas, where he was accepted to the materials science graduate program at the University of California at Los Angeles with a fellowship.

“When I came out of the airplane and went to the dorm for the first day, people were drinking Corona on the balcony, playing music, and there was beautiful weather, and I thought, this is where I’m supposed to be!” Kim recalls.

For his PhD, he began to dive into the microscopic world of electronic materials, seeking ways to manipulate them to make faster electronics. The subject was a focus for his advisor, who previously worked at Bell Labs, where many computing innovations originated at the time.

“A lot of the papers I was reading were from Bell Labs, and IBM T.J. Watson, and I was so impressed, and thought: I really want to be a scientist there. That was my dream,” Kim says.

During his PhD program, he reached out to a scientist at IBM whose name kept coming up in the papers Kim was reading. In his initial letter, Kim wrote with a question about his own PhD work, which tackled a hard industry problem: how to stretch, or “strain,” silicon to minimize defects that would occur as more transistors are packed on a chip. 

The query opened a dialogue, and Kim eventually inquired and was accepted to an internship at the IBM T.J. Watson Research Center, just outside New York City. Soon after he arrived, his manager pitched him a challenge: He might be hired full-time if he could solve a new, harder problem, having to do with replacing silicon.

At the time, the electronics industry was looking to germanium as a possible successor to silicon. The material can conduct electrons at even smaller scales, which would enable germanium to be made into even tinier transistors, for faster, smaller, and more powerful devices. But there was no reliable way for germanium to be “doped” — an essential process that replaces some of a material’s atoms with another type of atom in a way that controls how electrons flow through the material.

“My manager told me he didn’t expect me to solve this. But I really wanted the job,” Kim says. “So day and night, I thought, how to solve this? And I always went back to the textbooks.”

Those textbooks reminded him of a fundamental rule: Replacing one atom with another would work well if both atoms were of similar size. This revelation triggered an idea. Perhaps germanium could be doped with a combination of two different atoms with an average atomic size that is similar to germanium’s.

“I came up with this idea, and right after, IBM showed that it worked. I was so amazed,” Kim says. “From that point, research became my passion. I did it because it was just so fun. Singing is not so different from performing research.”

As promised, he was hired as a postdoc and soon after, promoted to research staff member — a title he carried, literally, with pride.

“I was feeling so happy to be there,” Kim says. “I even wore my IBM badge to restaurants, and everywhere I went.”

Throughout his time at IBM, he learned to focus on research that directly impacts everyday human life, and how to apply the fundamentals to develop next-generation products.

“IBM really raised me up as an engineer who can identify the problems in an industry and find creative solutions to tackle the challenges,” he says.

Cycle of life

And yet, Kim felt he could do more. He was working on boundary-pushing research at one of the leading innovation hubs in the country, where “out-of-the-box” thinking was encouraged, and experimentally tested. But he wanted to explore beyond the company’s research portfolio, and also, find a way to pursue research not just as a profession but as a passion.

“My experience taught me that you can lead a very happy life as an engineer or scientist if your research becomes your hobby,” Kim says. “I wanted to teach this cycle — of happiness, research, and passion — to young people and help PhD students develop like artists or singers.”

In 2015, he packed his bags for MIT, where he accepted a junior faculty position in the Department of Mechanical Engineering. His first impressions upon arriving at the Institute?

“Freedom,” Kim says. “For me, free thinking — to compose music, innovate something totally new — is the most important thing. And the people at MIT are very talented and curious of all the things.”

Since he’s put down roots on campus, he has built up a highly productive research group, focused on fabricating ultra-thin, stackable, high-performance electronic materials and devices, which Kim envisions could be used to build hybrid electronic systems as small as a fingernail and as powerful as a supercomputer. He credits the group’s many innovations to the more than 40 students, postdocs, and research scientists who have contributed to his lab.

“I hope this is where they can learn that research can be an art,” Kim says. “To students especially, I hope they see that, if they enjoy what they do, then they can be whatever they want to be.”

The Northeast Microelectronics Internship Program (NMIP), an initiative of MIT’s Microsystems Technology Laboratories (MTL) to connect first- and second-year college students to careers in semiconductor and microelectronics industries, recently received a $75,000 grant to expand its reach and impact. The funding is part of $9.2 million in grants awarded by the Northeast Microelectronics Coalition (NEMC) Hub to boost technology advancement, workforce development, education, and student engagement across the Northeast Region.

NMIP was founded by Tomás Palacios, the Clarence J. LeBel Professor of Electrical Engineering at MIT, and director of MTL. The grant, he says, will help address a significant barrier limiting the number of students who pursue careers in critical technological fields.

“Undergraduate students are key for the future of our nation’s microelectronics workforce. They directly fill important roles that require technical fluency or move on to advanced degrees,” says Palacios. “But these students have repeatedly shared with us that the lack of internships in their first few semesters in college is the main reason why many move to industries with a more established tradition of hiring undergraduate students in their early years. This program connects students and industry partners to fix this issue.”

The NMIP funding was announced on Jan. 30 during an event featuring Massachusetts Governor Maura Healey, Lt. Governor Kim Driscoll, and Economic Development Secretary Yvonne Hao, as well as leaders from the U.S. Department of Defense and the director of Microelectronics Commons at NSTXL, the National Security Technology Accelerator. The grant to support NMIP is part of $1.5 million in new workforce development grants aimed at spurring the microelectronics and semiconductor industry across the Northeast Region. The new awards are the first investments made by the NEMC Hub, a division of the Massachusetts Technology Collaborative, that is overseeing investments made by the federal CHIPS and Science Act following the formal establishment of the NEMC Hub in September 2023.

“We are very excited for the recognition the program is receiving. It is growing quickly and the support will help us further dive into our mission to connect talented students to the broader microelectronics ecosystem while integrating our values of curiosity, openness, excellence, respect, and community,” says Preetha Kingsview, who manages the program. “This grant will help us connect to the broader community convened by NEMC Hub in close collaboration with MassTech. We are very excited for what this support will help NMIP achieve.”

The funds provided by the NEMC Microelectronics Commons Hub will help expand the program more broadly across the Northeast, to support students and grow the pool of skilled workers for the microelectronics sector regionally. After receiving 300 applications in the first two years, the program received 296 applications in 2024 from students interested in summer internships, and is working with more than 25 industry partners across the Northeast. These NMIP students not only participate in industry-focused summer internships, but are also exposed to the broader microelectronics ecosystem through bi-weekly field trips to microelectronics companies in the region.

“The expansion of the program across the Northeast, and potentially nationwide, will extend the impact of this program to reach more students and benefit more microelectronics companies across the region,” says Christine Nolan, acting NEMC Hub program director. “Through hands-on training opportunities we are able to showcase the amazing jobs that exist in this sector and to strengthen the pipeline of talented workers to support the mission of the NEMC Hub and the national CHIPs investments.”  

Sheila Wescott says her company, MACOM, a Lowell-based developer of semiconductor devices and components, is keenly interested in sourcing intern candidates from NMIP. “We already have a success story from this program,” she says. “One of our interns completed two summer programs with us and is continuing part time in the fall — and we anticipate him joining MACOM full time after graduation.”

“NMIP is an excellent platform to engage students with a diverse background and promote microelectronics technology,” says Bin Lu, CTO and co-founder of Finwave Semiconductor.  “Finwave has benefited from engaging with the young engineers who are passionate about working with electronics and cutting-edge semiconductor technology. We are committed to continuing to work with NMIP.”

Many vaccines, including vaccines for hepatitis B and whooping cough, consist of fragments of viral or bacterial proteins. These vaccines often include other molecules called adjuvants, which help to boost the immune system’s response to the protein.

Most of these adjuvants consist of aluminum salts or other molecules that provoke a nonspecific immune response. A team of MIT researchers has now shown that a type of nanoparticle called a metal organic framework (MOF) can also provoke a strong immune response, by activating the innate immune system — the body’s first line of defense against any pathogen — through cell proteins called toll-like receptors.

In a study of mice, the researchers showed that this MOF could successfully encapsulate and deliver part of the SARS-CoV-2 spike protein, while also acting as an adjuvant once the MOF is broken down inside cells.

While more work would be needed to adapt these particles for use as vaccines, the study demonstrates that this type of structure can be useful for generating a strong immune response, the researchers say.

“Understanding how the drug delivery vehicle can enhance an adjuvant immune response is something that could be very helpful in designing new vaccines,” says Ana Jaklenec, a principal investigator at MIT’s Koch Institute for Integrative Cancer Research and one of the senior authors of the new study.

Robert Langer, an MIT Institute Professor and member of the Koch Institute, and Dan Barouch, director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center and a professor at Harvard Medical School, are also senior authors of the paper, which appears today in Science Advances. The paper’s lead author is former MIT postdoc and Ibn Khaldun Fellow Shahad Alsaiari.

Immune activation

In this study, the researchers focused on a MOF called ZIF-8, which consists of a lattice of tetrahedral units made up of a zinc ion attached to four molecules of imidazole, an organic compound. Previous work has shown that ZIF-8 can significantly boost immune responses, but it wasn’t known exactly how this particle activates the immune system.

To try to figure that out, the MIT team created an experimental vaccine consisting of the SARS-CoV-2 receptor-binding protein (RBD) embedded within ZIF-8 particles. These particles are between 100 and 200 nanometers in diameter, a size that allows them to get into the body’s lymph nodes directly or through immune cells such as macrophages.

Once the particles enter the cells, the MOFs are broken down, releasing the viral proteins. The researchers found that the imidazole components then activate toll-like receptors (TLRs), which help to stimulate the innate immune response.

“This process is analogous to establishing a covert operative team at the molecular level to transport essential elements of the Covid-19 virus to the body’s immune system, where they can activate specific immune responses to boost vaccine efficacy,” Alsaiari says.

RNA sequencing of cells from the lymph nodes showed that mice vaccinated with ZIF-8 particles carrying the viral protein strongly activated a TLR pathway known as TLR-7, which led to greater production of cytokines and other molecules involved in inflammation.

Mice vaccinated with these particles generated a much stronger response to the viral protein than mice that received the protein on its own.

“Not only are we delivering the protein in a more controlled way through a nanoparticle, but the compositional structure of this particle is also acting as an adjuvant,” Jaklenec says. “We were able to achieve very specific responses to the Covid protein, and with a dose-sparing effect compared to using the protein by itself to vaccinate.”

Vaccine access

While this study and others have demonstrated ZIF-8’s immunogenic ability, more work needs to be done to evaluate the particles’ safety and potential to be scaled up for large-scale manufacturing. If ZIF-8 is not developed as a vaccine carrier, the findings from the study should help to guide researchers in developing similar nanoparticles that could be used to deliver subunit vaccines, Jaklenec says.

“Most subunit vaccines usually have two separate components: an antigen and an adjuvant,” Jaklenec says. “Designing new vaccines that utilize nanoparticles with specific chemical moieties which not only aid in antigen delivery but can also activate particular immune pathways have the potential to enhance vaccine potency.”

One advantage to developing a subunit vaccine for Covid-19 is that such vaccines are usually easier and cheaper to manufacture than mRNA vaccines, which could make it easier to distribute them around the world, the researchers say.

“Subunit vaccines have been around for a long time, and they tend to be cheaper to produce, so that opens up more access to vaccines, especially in times of pandemic,” Jaklenec says.

The research was funded by Ibn Khaldun Fellowships for Saudi Arabian Women and in part by the Koch Institute Support (core) Grant from the U.S. National Cancer Institute.

Benjamin Warf, a renowned neurosurgeon at Boston Children’s Hospital, stands in the MIT.nano Immersion Lab. More than 3,000 miles away, his virtual avatar stands next to Matheus Vasconcelos in Brazil as the resident practices delicate surgery on a doll-like model of a baby’s brain.

With a pair of virtual-reality goggles, Vasconcelos is able to watch Warf’s avatar demonstrate a brain surgery procedure before replicating the technique himself and while asking questions of Warf’s digital twin.

“It’s an almost out-of-body experience,” Warf says of watching his avatar interact with the residents. “Maybe it’s how it feels to have an identical twin?”

And that’s the goal: Warf’s digital twin bridged the distance, allowing him to be functionally in two places at once. “It was my first training using this model, and it had excellent performance,” says Vasconcelos, a neurosurgery resident at Santa Casa de São Paulo School of Medical Sciences in São Paulo, Brazil. “As a resident, I now feel more confident and comfortable applying the technique in a real patient under the guidance of a professor.”

Warf’s avatar arrived via a new project launched by medical simulator and augmented reality (AR) company EDUCSIM. The company is part of the 2023 cohort of START.nano, MIT.nano’s deep-tech accelerator that offers early-stage startups discounted access to MIT.nano’s laboratories.

In March 2023, Giselle Coelho, EDUCSIM’s scientific director and a pediatric neurosurgeon at Santa Casa de São Paulo and Sabará Children’s Hospital, began working with technical staff in the MIT.nano Immersion Lab to create Warf’s avatar. By November, the avatar was training future surgeons like Vasconcelos.

“I had this idea to create the avatar of Dr. Warf as a proof of concept, and asked, ‘What would be the place in the world where they are working on technologies like that?’” Coelho says. “Then I found MIT.nano.”

Capturing a Surgeon

As a neurosurgery resident, Coelho was so frustrated by the lack of practical training options for complex surgeries that she built her own model of a baby brain. The physical model contains all the structures of the brain and can even bleed, “simulating all the steps of a surgery, from incision to skin closure,” she says.

She soon found that simulators and virtual reality (VR) demonstrations reduced the learning curve for her own residents. Coelho launched EDUCSIM in 2017 to expand the variety and reach of the training for residents and experts looking to learn new techniques.

Those techniques include a procedure to treat infant hydrocephalus that was pioneered by Warf, the director of neonatal and congenital neurosurgery at Boston Children’s Hospital. Coelho had learned the technique directly from Warf and thought his avatar might be the way for surgeons who couldn’t travel to Boston to benefit from his expertise.

To create the avatar, Coelho worked with Talis Reks, the AR/VR/gaming/big data IT technologist in the Immersion Lab.

“A lot of technology and hardware can be very expensive for startups to access as they start their company journey,” Reks explains. “START.nano is one way of enabling them to utilize and afford the tools and technologies we have at MIT.nano’s Immersion Lab.”

Coelho and her colleagues needed high-fidelity and high-resolution motion-capture technology, volumetric video capture, and a range of other VR/AR technologies to capture Warf’s dexterous finger motions and facial expressions. Warf visited MIT.nano on several occasions to be digitally “captured,” including performing an operation on the physical baby model while wearing special gloves and clothing embedded with sensors.

“These technologies have mostly been used for entertainment or VFX [visual effects] or CGI [computer-generated imagery],” says Reks, “But this is a unique project, because we’re applying it now for real medical practice and real learning.”

One of the biggest challenges, Reks says, was helping to develop what Coelho calls “holoportation”— transmitting the 3D, volumetric video capture of Warf in real-time over the internet so that his avatar can appear in transcontinental medical training.

The Warf avatar has synchronous and asynchronous modes. The training that Vasconcelos received was in the asynchronous mode, where residents can observe the avatar’s demonstrations and ask it questions. The answers, delivered in a variety of languages, come from AI algorithms that draw from previous research and an extensive bank of questions and answers provided by Warf.

In the synchronous mode, Warf operates his avatar from a distance in real time, Coelho says. “He could walk around the room, he could talk to me, he could orient me. It’s amazing.”

Coelho, Warf, Reks, and other team members demonstrated a combination of the modes in a second session in late December. This demo consisted of volumetric live video capture between the Immersion Lab and Brazil, spatialized and visible in real-time through AR headsets. It significantly expanded upon the previous demo, which had only streamed volumetric data in one direction through a two-dimensional display.

Powerful impacts

Warf has a long history of training desperately needed pediatric neurosurgeons around the world, most recently through his nonprofit Neurokids. Remote and simulated training has been an increasingly large part of training since the pandemic, he says, although he doesn’t feel it will ever completely replace personal hands-on instruction and collaboration.

“But if in fact one day we could have avatars, like this one from Giselle, in remote places showing people how to do things and answering questions for them, without the cost of travel, without the time cost and so forth, I think it could be really powerful,” Warf says.

The avatar project is especially important for surgeons serving remote and underserved areas like the Amazon region of Brazil, Coelho says. “This is a way to give them the same level of education that they would get in other places, and the same opportunity to be in touch with Dr. Warf.”

One baby treated for hydrocephalus at a recent Amazon clinic had traveled by boat 30 hours for the surgery, according to Coelho.

Training surgeons with the avatar, she says, “can change reality for this baby and can change the future.”

Perovskites, a broad class of compounds with a particular kind of crystal structure, have long been seen as a promising alternative or supplement to today’s silicon or cadmium telluride solar panels. They could be far more lightweight and inexpensive, and could be coated onto virtually any substrate, including paper or flexible plastic that could be rolled up for easy transport.

In their efficiency at converting sunlight to electricity, perovskites are becoming comparable to silicon, whose manufacture still requires long, complex, and energy-intensive processes. One big remaining drawback is longevity: They tend to break down in a matter of months to years, while silicon solar panels can last more than two decades. And their efficiency over large module areas still lags behind silicon. Now, a team of researchers at MIT and several other institutions has revealed ways to optimize efficiency and better control degradation, by engineering the nanoscale structure of perovskite devices.

The study reveals new insights on how to make high-efficiency perovskite solar cells, and also provides new directions for engineers working to bring these solar cells to the commercial marketplace. The work is described today in the journal Nature Energy, in a paper by Dane deQuilettes, a recent MIT postdoc who is now co-founder and chief science officer of the MIT spinout Optigon, along with MIT professors Vladimir Bulovic and Moungi Bawendi, and 10 others at MIT and in Washington state, the U.K., and Korea.

“Ten years ago, if you had asked us what would be the ultimate solution to the rapid development of solar technologies, the answer would have been something that works as well as silicon but whose manufacturing is much simpler,” Bulovic says. “And before we knew it, the field of perovskite photovoltaics appeared. They were as efficient as silicon, and they were as easy to paint on as it is to paint on a piece of paper. The result was tremendous excitement in the field.”

Nonetheless, “there are some significant technical challenges of handling and managing this material in ways we’ve never done before,” he says. But the promise is so great that many hundreds of researchers around the world have been working on this technology. The new study looks at a very small but key detail: how to “passivate” the material’s surface, changing its properties in such a way that the perovskite no longer degrades so rapidly or loses efficiency.

“The key is identifying the chemistry of the interfaces, the place where the perovskite meets other materials,” Bulovic says, referring to the places where different materials are stacked next to perovskite in order to facilitate the flow of current through the device.

Engineers have developed methods for passivation, for example by using a solution that creates a thin passivating coating. But they’ve lacked a detailed understanding of how this process works — which is essential to make further progress in finding better coatings. The new study “addressed the ability to passivate those interfaces and elucidate the physics and science behind why this passivation works as well as it does,” Bulovic says.

The team used some of the most powerful instruments available at laboratories around the world to observe the interfaces between the perovskite layer and other materials, and how they develop, in unprecedented detail. This close examination of the passivation coating process and its effects resulted in “the clearest roadmap as of yet of what we can do to fine-tune the energy alignment at the interfaces of perovskites and neighboring materials,” and thus improve their overall performance, Bulovic says.

While the bulk of a perovskite material is in the form of a perfectly ordered crystalline lattice of atoms, this order breaks down at the surface. There may be extra atoms sticking out or vacancies where atoms are missing, and these defects cause losses in the material’s efficiency. That’s where the need for passivation comes in.

“This paper is essentially revealing a guidebook for how to tune surfaces, where a lot of these defects are, to make sure that energy is not lost at surfaces,” deQuilettes says. “It’s a really big discovery for the field,” he says. “This is the first paper that demonstrates how to systematically control and engineer surface fields in perovskites.”

The common passivation method is to bathe the surface in a solution of a salt called hexylammonium bromide, a technique developed at MIT several years ago by Jason Jungwan Yoo PhD ’20, who is a co-author of this paper, that led to multiple new world-record efficiencies. By doing that “you form a very thin layer on top of your defective surface, and that thin layer actually passivates a lot of the defects really well,” deQuilettes says. “And then the bromine, which is part of the salt, actually penetrates into the three-dimensional layer in a controllable way.” That penetration helps to prevent electrons from losing energy to defects at the surface.

These two effects, produced by a single processing step, produces the two beneficial changes simultaneously. “It’s really beautiful because usually you need to do that in two steps,” deQuilettes says.

The passivation reduces the energy loss of electrons at the surface after they have been knocked loose by sunlight. These losses reduce the overall efficiency of the conversion of sunlight to electricity, so reducing the losses boosts the net efficiency of the cells.

That could rapidly lead to improvements in the materials’ efficiency in converting sunlight to electricity, he says. The recent efficiency records for a single perovskite layer, several of them set at MIT, have ranged from about 24 to 26 percent, while the maximum theoretical efficiency that could be reached is about 30 percent, according to deQuilettes.

An increase of a few percent may not sound like much, but in the solar photovoltaic industry such improvements are highly sought after. “In the silicon photovoltaic industry, if you’re gaining half of a percent in efficiency, that’s worth hundreds of millions of dollars on the global market,” he says. A recent shift in silicon cell design, essentially adding a thin passivating layer and changing the doping profile, provides an efficiency gain of about half of a percent. As a result, “the whole industry is shifting and rapidly trying to push to get there.” The overall efficiency of silicon solar cells has only seen very small incremental improvements for the last 30 years, he says.

The record efficiencies for perovskites have mostly been set in controlled laboratory settings with small postage-stamp-size samples of the material. “Translating a record efficiency to commercial scale takes a long time,” deQuilettes says. “Another big hope is that with this understanding, people will be able to better engineer large areas to have these passivating effects.”

There are hundreds of different kinds of passivating salts and many different kinds of perovskites, so the basic understanding of the passivation process provided by this new work could help guide researchers to find even better combinations of materials, the researchers suggest. “There are so many different ways you could engineer the materials,” he says.

“I think we are on the doorstep of the first practical demonstrations of perovskites in the commercial applications,” Bulovic says. “And those first applications will be a far cry from what we’ll be able to do a few years from now.” He adds that perovskites “should not be seen as a displacement of silicon photovoltaics. It should be seen as an augmentation — yet another way to bring about more rapid deployment of solar electricity.”

“A lot of progress has been made in the last two years on finding surface treatments that improve perovskite solar cells,” says Michael McGehee, a professor of chemical engineering at the University of Colorado who was not associated with this research. “A lot of the research has been empirical with the mechanisms behind the improvements not being fully understood. This detailed study shows that treatments can not only passivate defects, but can also create a surface field that repels carriers that should be collected at the other side of the device. This understanding might help further improve the interfaces.”

The team included researchers at the Korea Research Institute of Chemical Technology, Cambridge University, the University of Washington in Seattle, and Sungkyunkwan University in Korea. The work was supported by the Tata Trust, the MIT Institute for Soldier Nanotechnologies, the U.S. Department of Energy, and the U.S. National Science Foundation.

Experimental computer memories and processors built from magnetic materials use far less energy than traditional silicon-based devices. Two-dimensional magnetic materials, composed of layers that are only a few atoms thick, have incredible properties that could allow magnetic-based devices to achieve unprecedented speed, efficiency, and scalability.

While many hurdles must be overcome until these so-called van der Waals magnetic materials can be integrated into functioning computers, MIT researchers took an important step in this direction by demonstrating precise control of a van der Waals magnet at room temperature.

This is key, since magnets composed of atomically thin van der Waals materials can typically only be controlled at extremely cold temperatures, making them difficult to deploy outside a laboratory.

The researchers used pulses of electrical current to switch the direction of the device’s magnetization at room temperature. Magnetic switching can be used in computation, the same way a transistor switches between open and closed to represent 0s and 1s in binary code, or in computer memory, where switching enables data storage.

The team fired bursts of electrons at a magnet made of a new material that can sustain its magnetism at higher temperatures. The experiment leveraged a fundamental property of electrons known as spin, which makes the electrons behave like tiny magnets. By manipulating the spin of electrons that strike the device, the researchers can switch its magnetization.

“The heterostructure device we have developed requires an order of magnitude lower electrical current to switch the van der Waals magnet, compared to that required for bulk magnetic devices,” says Deblina Sarkar, the AT&T Career Development Assistant Professor in the MIT Media Lab and Center for Neurobiological Engineering, head of the Nano-Cybernetic Biotrek Lab, and the senior author of a paper on this technique. “Our device is also more energy efficient than other van der Waals magnets that are unable to switch at room temperature.”

In the future, such a magnet could be used to build faster computers that consume less electricity. It could also enable magnetic computer memories that are nonvolatile, which means they don’t leak information when powered off, or processors that make complex AI algorithms more energy-efficient.

“There is a lot of inertia around trying to improve materials that worked well in the past. But we have shown that if you make radical changes, starting by rethinking the materials you are using, you can potentially get much better solutions,” says Shivam Kajale, a graduate student in Sarkar’s lab and co-lead author of the paper.

Kajale and Sarkar are joined on the paper by co-lead author Thanh Nguyen, a graduate student in the Department of Nuclear Science and Engineering (NSE); Corson Chao, a graduate student in the Department of Materials Science and Engineering (DSME); David Bono, a DSME research scientist; Artittaya Boonkird, an NSE graduate student; and Mingda Li, associate professor of nuclear science and engineering. The research appears this week in Nature Communications.

An atomically thin advantage

Methods to fabricate tiny computer chips in a clean room from bulk materials like silicon can hamper devices. For instance, the layers of material may be barely 1 nanometer thick, so minuscule rough spots on the surface can be severe enough to degrade performance.

By contrast, van der Waals magnetic materials are intrinsically layered and structured in such a way that the surface remains perfectly smooth, even as researchers peel off layers to make thinner devices. In addition, atoms in one layer won’t leak into other layers, enabling the materials to retain their unique properties when stacked in devices.

“In terms of scaling and making these magnetic devices competitive for commercial applications, van der Waals materials are the way to go,” Kajale says.

But there’s a catch. This new class of magnetic materials have typically only been operated at temperatures below 60 kelvins (-351 degrees Fahrenheit). To build a magnetic computer processor or memory, researchers need to use electrical current to operate the magnet at room temperature.

To achieve this, the team focused on an emerging material called iron gallium telluride. This atomically thin material has all the properties needed for effective room temperature magnetism and doesn’t contain rare earth elements, which are undesirable because extracting them is especially destructive to the environment.

Nguyen carefully grew bulk crystals of this 2D material using a special technique. Then, Kajale fabricated a two-layer magnetic device using nanoscale flakes of iron gallium telluride underneath a six-nanometer layer of platinum.

Tiny device in hand, they used an intrinsic property of electrons known as spin to switch its magnetization at room temperature.

Electron ping-pong

While electrons don’t technically “spin” like a top, they do possess the same kind of angular momentum. That spin has a direction, either up or down. The researchers can leverage a property known as spin-orbit coupling to control the spins of electrons they fire at the magnet.

The same way momentum is transferred when one ball hits another, electrons will transfer their “spin momentum” to the 2D magnetic material when they strike it. Depending on the direction of their spins, that momentum transfer can reverse the magnetization.

In a sense, this transfer rotates the magnetization from up to down (or vice-versa), so it is called a “torque,” as in spin-orbit torque switching. Applying a negative electric pulse causes the magnetization to go downward, while a positive pulse causes it to go upward.

The researchers can do this switching at room temperature for two reasons: the special properties of iron gallium telluride and the fact that their technique uses small amounts of electrical current. Pumping too much current into the device would cause it to overheat and demagnetize.

The team faced many challenges over the two years it took to achieve this milestone, Kajale says. Finding the right magnetic material was only half the battle. Since iron gallium telluride oxidizes quickly, fabrication must be done inside a glovebox filled with nitrogen.

“The device is only exposed to air for 10 or 15 seconds, but even after that I have to do a step where I polish it to remove any oxide,” he says.

Now that they have demonstrated room-temperature switching and greater energy efficiency, the researchers plan to keep pushing the performance of magnetic van der Waals materials.

“Our next milestone is to achieve switching without the need for any external magnetic fields. Our aim is to enhance our technology and scale up to bring the versatility of van der Waals magnet to commercial applications,” Sarkar says.

This work was carried out, in part, using the facilities at MIT.Nano and the Harvard University Center for Nanoscale Systems.

Seated at the grand piano in MIT’s Killian Hall last fall, first-year student Jacqueline Wang played through the lively opening of Mozart’s “Sonata in B-flat major, K.333.” When she’d finished, Mi-Eun Kim, pianist and lecturer in MIT’s Music and Theater Arts Section (MTA), asked her to move to the rear of the hall. Kim tapped at an iPad. Suddenly, the sonata she'd just played poured forth again from the piano — its keys dipping and rising just as they had with Wang’s fingers on them, the resonance of its strings filling the room. Wang stood among a row of empty seats with a slightly bemused expression, taking in a repeat of her own performance.

“That was a little strange,” Wang admitted when the playback concluded, then added thoughtfully: “It sounds different from what I imagine I’m playing.”

This unusual lesson took place during a nearly three-week residency at MIT of the Steinway Spirio | r, a piano embedded with technology for live performance capture and playback. “The residency offered students, faculty, staff, and campus visitors the opportunity to engage with this new technology through a series of workshops that focused on such topics as the historical analysis of piano design, an examination of the hardware and software used by the Spirio | r, and step-by-step guidance of how to use the features,” explains Keeril Makan, head of MIT Music and Theater Arts and associate dean of the School of Humanities, Arts, and Social Sciences.

Wang was one of several residency participants to have the out-of-body experience of hearing herself play from a different vantage point, while watching the data of her performance scroll across a screen: color-coded rectangles indicating the velocity and duration of each note, an undulating line charting her use of the damper pedal. Wang was even able to edit her own performance, as she discovered when Kim suggested her rhythmic use of the pedal might be superfluous. Using the iPad interface to erase the pedaling entirely, they listened to the playback again, the notes gaining new clarity.

“See? We don’t need it,” Kim confirmed with a smile.

“When MIT’s new music building (W18) opens in spring 2025, we hope it will include this type of advanced technology. It would add value not just to Wang’s cohort of 19 piano students in the Emerson/Harris Program, which provides a total of 71 scholars and fellows with support for conservatory-level instruction in classical, jazz, and world music. But could also offer educational opportunities to a much wider swath of the MIT community,” says Makan. “Music is the fifth-most popular minor at MIT; 1,700 students enroll in music and theater arts classes each semester, and the Institute is brimming with vocalists, composers, instrumentalists, and music history students.”

According to Kim, the Spirio enables insights beyond what musicians could learn from a conventional recording; hearing playback directly from the instrument reveals sonic dimensions an MP3 can’t capture. “Speaker systems sort of crunch everything down — the highs and the lows, they all kind of sound the same. But piano solo music is very dynamic. It’s supposed to be experienced in a room,” she says.

During the Spirio | r residency, students found they could review their playing at half speed, adjust the volume of certain notes to emphasize a melody, transpose a piece to another key, or layer their performance — prerecording one hand, for example, then accompanying it live with the other.

“It helps the student be part of the learning and the teaching process,” Kim says. “If there’s a gap between what they imagined and what they hear and then they come to me and say, ‘How do I fix this?’ they’re definitely more engaged. It’s an honest representation of their playing, and the students who are humbled by it will become better pianists.”

For Wang, reflecting on her lesson with Kim, the session introduced an element she’d never experienced since beginning her piano studies at age 5. “The visual display of how long each key was played and with what velocity gave me a more precise demonstration of the ideas of voicing and evenness,” Wang says. “Playing the piano is usually dependent solely on the ears, but this combines with the auditory experience a visual experience and statistics, which helped me get a more holistic view of my playing.”

As a first-year undergraduate considering a Course 6 major (electrical engineering and computer science, or EECS), Wang was also fascinated to watch Patrick Elisha, a representative from Steinway dealer M. Steinert & Sons, disassemble the piano action to point out the optical sensors that measure the velocity of each hammer strike at 1,020 levels of sensitivity, sampled 800 times per second.

“I was amazed by the precision of the laser sensors and inductors,” says Wang. “I have just begun to take introductory-level courses in EECS and am just coming across these concepts, and this certainly made me more excited to learn more about these electrical devices and their applications. I was also intrigued that the electrical system was added onto the piano without interfering with the mechanical structure, so that when we play the Spirio, our experience with the touch and finger control was just like that of playing a usual Steinway.”

Another Emerson/Harris scholar, Víctor Quintas-Martínez, a PhD candidate in economics who resumed his lapsed piano studies during the Covid-19 pandemic, visited Killian Hall during the residency to rehearse a Fauré piano quartet with a cellist, violist, and violinist. “We did a run of certain passages and recorded the piano part. Then I listened to the strings play with the recording from the back of the hall. That gave me an idea of what I needed to adjust in terms of volume, texture, pedal, etc., to achieve a better balance. Normally, when you’re playing, because you’re sitting behind the strings and close to the piano, your perception of balance may be somewhat distorted,” he notes.

Kim cites another campus demographic ripe for exploring these types of instruments like the Spirio | r and its software: future participants in MIT’s relatively new Music Technology Master's Program, along with others across the Institute whose work intersects with the wealth of data the instrument captures. Among them is Praneeth Namburi, a research scientist at the MIT.nano Immersion Lab. Typically, Namburi focuses his neuroscience expertise on the biomechanics of dancing and expert movement. For two days during the MTA/Spirio residency, he used the sensors at the Immersion Lab, along with those of the Spirio, to analyze how pianists use their bodies.

“We used motion capture that can help us contrast the motion paths of experts such as Mi-Eun from those of students, potentially aiding in music education,” Namburi recounts, “force plates that can give scientific insights into how movement timing is organized, and ultrasound to visualize the forearm tissues during playing, which can potentially help us understand musicianship-related injuries.”

“The encounter between MTA and MIT.nano was something unique to MIT,” Kim believes. “Not only is this super useful for the music world, but it’s also very exciting for movement researchers, because playing piano is one of the most complex activities that humans do with our hands.”

In Kim’s view, that quintessentially human complexity is complemented by these kinds of technical possibilities. “Some people might think oh, it's going to replace the pianist,” she says. “But in the end it is a tool. It doesn’t replace all of the things that go into learning music. I think it's going to be an invaluable third partner: the student, the teacher, and the Spirio — or the musician, the researcher, and the Spirio. It's going to play an integral role in a lot of musical endeavors.”

In quantum sensing, atomic-scale quantum systems are used to measure electromagnetic fields, as well as properties like rotation, acceleration, and distance, far more precisely than classical sensors can. The technology could enable devices that image the brain with unprecedented detail, for example, or air traffic control systems with precise positioning accuracy.

As many real-world quantum sensing devices are emerging, one promising direction is the use of microscopic defects inside diamonds to create “qubits” that can be used for quantum sensing. Qubits are the building blocks of quantum devices.

Researchers at MIT and elsewhere have developed a technique that enables them to identify and control a greater number of these microscopic defects. This could help them build a larger system of qubits that can perform quantum sensing with greater sensitivity.

Their method builds off a central defect inside a diamond, known as a nitrogen-vacancy (NV) center, which scientists can detect and excite using laser light and then control with microwave pulses. This new approach uses a specific protocol of microwave pulses to identify and extend that control to additional defects that can’t be seen with a laser, which are called dark spins.

The researchers seek to control larger numbers of dark spins by locating them through a network of connected spins. Starting from this central NV spin, the researchers build this chain by coupling the NV spin to a nearby dark spin, and then use this dark spin as a probe to find and control a more distant spin which can’t be sensed by the NV directly. The process can be repeated on these more distant spins to control longer chains.

“One lesson I learned from this work is that searching in the dark may be quite discouraging when you don’t see results, but we were able to take this risk. It is possible, with some courage, to search in places that people haven’t looked before and find potentially more advantageous qubits,” says Alex Ungar, a PhD student in electrical engineering and computer science and a member of the Quantum Engineering Group at MIT, who is lead author of a paper on this technique, which is published today in PRX Quantum.

His co-authors include his advisor and corresponding author, Paola Cappellaro, the Ford Professor of Engineering in the Department of Nuclear Science and Engineering and professor of physics; as well as Alexandre Cooper, a senior research scientist at the University of Waterloo’s Institute for Quantum Computing; and Won Kyu Calvin Sun, a former researcher in Cappellaro’s group who is now a postdoc at the University of Illinois at Urbana-Champaign.

Diamond defects

To create NV centers, scientists implant nitrogen into a sample of diamond.

But introducing nitrogen into the diamond creates other types of atomic defects in the surrounding environment. Some of these defects, including the NV center, can host what are known as electronic spins, which originate from the valence electrons around the site of the defect. Valence electrons are those in the outermost shell of an atom. A defect’s interaction with an external magnetic field can be used to form a qubit.

Researchers can harness these electronic spins from neighboring defects to create more qubits around a single NV center. This larger collection of qubits is known as a quantum register. Having a larger quantum register boosts the performance of a quantum sensor.

Some of these electronic spin defects are connected to the NV center through magnetic interaction. In past work, researchers used this interaction to identify and control nearby spins. However, this approach is limited because the NV center is only stable for a short amount of time, a principle called coherence. It can only be used to control the few spins that can be reached within this coherence limit.

In this new paper, the researchers use an electronic spin defect that is near the NV center as a probe to find and control an additional spin, creating a chain of three qubits.

They use a technique known as spin echo double resonance (SEDOR), which involves a series of microwave pulses that decouple an NV center from all electronic spins that are interacting with it. Then, they selectively apply another microwave pulse to pair the NV center with one nearby spin.

Unlike the NV, these neighboring dark spins can’t be excited, or polarized, with laser light. This polarization is a required step to control them with microwaves.

Once the researchers find and characterize a first-layer spin, they can transfer the NV’s polarization to this first-layer spin through the magnetic interaction by applying microwaves to both spins simultaneously. Then once the first-layer spin is polarized, they repeat the SEDOR process on the first-layer spin, using it as a probe to identify a second-layer spin that is interacting with it.

Controlling a chain of dark spins

This repeated SEDOR process allows the researchers to detect and characterize a new, distinct defect located outside the coherence limit of the NV center. To control this more distant spin, they carefully apply a specific series of microwave pulses that enable them to transfer the polarization from the NV center along the chain to this second-layer spin.

“This is setting the stage for building larger quantum registers to higher-layer spins or longer spin chains, and also showing that we can find these new defects that weren’t discovered before by scaling up this technique,” Ungar says.

To control a spin, the microwave pulses must be very close to the resonance frequency of that spin. Tiny drifts in the experimental setup, due to temperature or vibrations, can throw off the microwave pulses.

The researchers were able to optimize their protocol for sending precise microwave pulses, which enabled them to effectively identify and control second-layer spins, Ungar says.

“We are searching for something in the unknown, but at the same time, the environment might not be stable, so you don’t know if what you are finding is just noise. Once you start seeing promising things, you can put all your best effort in that one direction. But before you arrive there, it is a leap of faith,” Cappellaro says.

While they were able to effectively demonstrate a three-spin chain, the researchers estimate they could scale their method to a fifth layer using their current protocol, which could provide access to hundreds of potential qubits. With further optimization, they may be able to scale up to more than 10 layers.

In the future, they plan to continue enhancing their technique to efficiently characterize and probe other electronic spins in the environment and explore different types of defects that could be used to form qubits.

This research is supported, in part, by the U.S. National Science Foundation and the Canada First Research Excellence Fund.

A team of MIT researchers will lead a $65.67 million effort, awarded by the U.S. Advanced Research Projects Agency for Health (ARPA-H), to develop ingestible devices that may one day be used to treat diabetes, obesity, and other conditions through oral delivery of mRNA. Such devices could potentially be deployed for needle-free delivery of mRNA vaccines as well.

The five-year project also aims to develop electroceuticals, a new form of ingestible therapies based on electrical stimulation of the body’s own hormones and neural signaling. If successful, this approach could lead to new treatments for a variety of metabolic disorders.

“We know that the oral route is generally the preferred route of administration for both patients and health care providers,” says Giovanni Traverso, an associate professor of mechanical engineering at MIT and a gastroenterologist at Brigham and Women’s Hospital. “Our primary focus is on disorders of metabolism because they affect a lot of people, but the platforms we’re developing could be applied very broadly.”

Traverso is the principal investigator for the project, which also includes Robert Langer, MIT Institute Professor, and Anantha Chandrakasan, dean of the MIT School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science. As part of the project, the MIT team will collaborate with investigators from Brigham and Women’s Hospital, New York University, and the University of Colorado School of Medicine.

Over the past several years, Traverso’s and Langer’s labs have designed many types of ingestible devices that can deliver drugs to the GI tract. This approach could be especially useful for protein drugs and nucleic acids, which typically can’t be given orally because they break down in the acidic environment of the digestive tract.

Messenger RNA has already proven useful as a vaccine, directing cells to produce fragments of viral proteins that trigger an immune response. Delivering mRNA to cells also holds potential to stimulate production of therapeutic molecules to treat a variety of diseases. In this project, the researchers plan to focus on metabolic diseases such as diabetes.

“What mRNA can do is enable the potential for dosing therapies that are very difficult to dose today, or provide longer-term coverage by essentially creating an internal factory that produces a therapy for a prolonged period,” Traverso says.

In the mRNA portion of the project, the research team intends to identify lipid and polymer nanoparticle formulations that can most effectively deliver mRNA to cells, using machine learning to help identify the best candidates. They will also develop and test ingestible devices to carry the mRNA-nanoparticle payload, with the goal of running a clinical trial in the final year of the five-year project.

The work will build on research that Traverso’s lab has already begun. In 2022, Traverso and his colleagues reported that they could deliver mRNA in capsules that inject mRNA-nanoparticle complexes into the lining of the stomach.

The other branch of the project will focus on ingestible devices that can deliver a small electrical current to the lining of the stomach. In a study published last year, Traverso’s lab demonstrated this approach for the first time, using a capsule coated with electrodes that apply an electrical current to cells of the stomach. In animal studies, they found that this stimulation boosted production of ghrelin, a hormone that stimulates appetite.

Traverso envisions that this type of treatment could potentially replace or complement some of the existing drugs used to prevent nausea and stimulate appetite in people with anorexia or cachexia (loss of body mass that can occur in patients with cancer or other chronic diseases). The researchers also hope to develop ways to stimulate production of GLP-1, a hormone that is used to help manage diabetes and promote weight loss.

“What this approach starts to do is potentially maximize our ability to treat disease without administering a new drug, but instead by simply modulating the body’s own systems through electrical stimulation,” Traverso says.

At MIT, Langer will help to develop nanoparticles for mRNA delivery, and Chandrakasan will work on ways to reduce energy consumption and miniaturize the electronic functions of the capsules, including secure communication, stimulation, and power generation.

The Brigham and Women’s Hospital’s portion of the project will be co-led by Traverso, Ameya Kirtane, Jason Li, and Peter Chai, who will amplify efforts on the formulation and stabilization of the mRNA nanoparticles, engineering of the ingestible devices, and running of clinical trials. At NYU, the effort will be led by assistant professor of bioengineering Khalil Ramadi SM ’16, PhD ’19, focusing on biological characterization of the effects of electrical stimulation. Researchers at the University of Colorado, led by Matthew Wynia and Eric G. Campbell of the CU Center for Bioethics and Humanities, will focus on exploring the ethical dimensions and public perceptions of these types of biomedical interventions.

“We felt like we had an opportunity here not only to do fundamental engineering science and early-stage clinical trials, but also to start to understand the data behind some of the ethical implications and public perceptions of these technologies through this broad collaboration,” Traverso says.

The project described here is supported by ARPA-H under award number D24AC00040-00. The content of this announcement does not necessarily represent the official views of the Advanced Research Projects Agency for Health.

A new set of advanced nanofabrication equipment will make MIT.nano one of the world’s most advanced research facilities in microelectronics and related technologies, unlocking new opportunities for experimentation and widening the path for promising inventions to become impactful new products.

The equipment, provided by Applied Materials, will significantly expand MIT.nano’s nanofabrication capabilities, making them compatible with wafers — thin, round slices of semiconductor material — up to 200 millimeters, or 8 inches, in diameter, a size widely used in industry. The new tools will allow researchers to prototype a vast array of new microelectronic devices using state-of-the-art materials and fabrication processes. At the same time, the 200-millimeter compatibility will support close collaboration with industry and enable innovations to be rapidly adopted by companies and mass produced.

MIT.nano’s leaders say the equipment, which will also be available to scientists outside of MIT, will dramatically enhance their facility’s capabilities, allowing experts in the region to more efficiently explore new approaches in “tough tech” sectors, including advanced electronics, next-generation batteries, renewable energies, optical computing, biological sensing, and a host of other areas — many likely yet to be imagined.

“The toolsets will provide an accelerative boost to our ability to launch new technologies that can then be given to the world at scale,” says MIT.nano Director Vladimir Bulović, who is also the Fariborz Maseeh Professor of Emerging Technology. “MIT.nano is committed to its expansive mission — to build a better world. We provide toolsets and capabilities that, in the hands of brilliant researchers, can effectively move the world forward.”

The announcement comes as part of an agreement between MIT and Applied Materials, Inc. that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities at MIT.nano.

“We don’t believe there is another space in the United States that will offer the same kind of versatility, capability, and accessibility, with 8-inch toolsets integrated right next to more fundamental toolsets for research discoveries,” Bulović says. “It will create a seamless path to accelerate the pace of innovation.”

Pushing the boundaries of innovation

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150- and 200-millimeter wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied Materials engineers will develop new process capabilities to benefit researchers and students from MIT and beyond.

“This investment will significantly accelerate the pace of innovation and discovery in microelectronics and microsystems,” says Tomás Palacios, director of MIT’s Microsystems Technology Laboratories and the Clarence J. Lebel Professor in Electrical Engineering. “It’s wonderful news for our community, wonderful news for the state, and, in my view, a tremendous step forward toward implementing the national vision for the future of innovation in microelectronics.”

Nanoscale research at universities is traditionally conducted on machines that are less compatible with industry, which makes academic innovations more difficult to turn into impactful, mass-produced products. Jorg Scholvin, associate director for MIT.nano’s shared fabrication facility, says the new machines, when combined with MIT.nano’s existing equipment, represent a step-change improvement in that area: Researchers will be able to take an industry-standard wafer and build their technology on top of it to prove to companies it works on existing devices, or to co-fabricate new ideas in close collaboration with industry partners.

“In the journey from an idea to a fully working device, the ability to begin on a small scale, figure out what you want to do, rapidly debug your designs, and then scale it up to an industry-scale wafer is critical,” Scholvin says. “It means a student can test out their idea on wafer-scale quickly and directly incorporate insights into their project so that their processes are scalable. Providing such proof-of-principle early on will accelerate the idea out of the academic environment, potentially reducing years of added effort. Other tools at MIT.nano can supplement work on the 200-millimeter wafer scale, but the higher throughput and higher precision of the Applied equipment will provide researchers with repeatability and accuracy that is unprecedented for academic research environments. Essentially what you have is a sharper, faster, more precise tool to do your work.”

Scholvin predicts the equipment will lead to exponential growth in research opportunities.

“I think a key benefit of these tools is they allow us to push the boundary of research in a variety of different ways that we can predict today,” Scholvin says. “But then there are also unpredictable benefits, which are hiding in the shadows waiting to be discovered by the creativity of the researchers at MIT. With each new application, more ideas and paths usually come to mind — so that over time, more and more opportunities are discovered.”

Because the equipment is available for use by people outside of the MIT community, including regional researchers, industry partners, nonprofit organizations, and local startups, they will also enable new collaborations.

“The tools themselves will be an incredible meeting place — a place that can, I think, transpose the best of our ideas in a much more effective way than before,” Bulović says. “I’m extremely excited about that.”

Palacios notes that while microelectronics is best known for work making transistors smaller to fit on microprocessors, it’s a vast field that enables virtually all the technology around us, from wireless communications and high-speed internet to energy management, personalized health care, and more.

He says he’s personally excited to use the new machines to do research around power electronics and semiconductors, including exploring promising new materials like gallium nitride, which could dramatically improve the efficiency of electronic devices.

Fulfilling a mission

MIT.nano’s leaders say a key driver of commercialization will be startups, both from MIT and beyond.

“This is not only going to help the MIT research community innovate faster, it’s also going to enable a new wave of entrepreneurship,” Palacios says. “We’re reducing the barriers for students, faculty, and other entrepreneurs to be able to take innovation and get it to market. That fits nicely with MIT’s mission of making the world a better place through technology. I cannot wait to see the amazing new inventions that our colleagues and students will come out with.”

Bulović says the announcement aligns with the mission laid out by MIT’s leaders at MIT.nano’s inception.

"We have the space in MIT.nano to accommodate these tools, we have the capabilities inside MIT.nano to manage their operation, and as a shared and open facility, we have methodologies by which we can welcome anyone from the region to use the tools,” Bulović says. “That is the vision MIT laid out as we were designing MIT.nano, and this announcement helps to fulfill that vision.”

The following is a joint announcement from MIT and Applied Materials, Inc.

MIT and Applied Materials, Inc., announced an agreement today that, together with a grant to MIT from the Northeast Microelectronics Coalition (NEMC) Hub, commits more than $40 million of estimated private and public investment to add advanced nano-fabrication equipment and capabilities to MIT.nano, the Institute’s center for nanoscale science and engineering. The collaboration will create a unique open-access site in the United States that supports research and development at industry-compatible scale using the same equipment found in high-volume production fabs to accelerate advances in silicon and compound semiconductors, power electronics, optical computing, analog devices, and other critical technologies.

The equipment and related funding and in-kind support provided by Applied Materials will significantly enhance MIT.nano’s existing capabilities to fabricate up to 200-millimeter (8-inch) wafers, a size essential to industry prototyping and production of semiconductors used in a broad range of markets including consumer electronics, automotive, industrial automation, clean energy, and more. Positioned to fill the gap between academic experimentation and commercialization, the equipment will help establish a bridge connecting early-stage innovation to industry pathways to the marketplace.

“A brilliant new concept for a chip won’t have impact in the world unless companies can make millions of copies of it. MIT.nano’s collaboration with Applied Materials will create a critical open-access capacity to help innovations travel from lab bench to industry foundries for manufacturing,” says Maria Zuber, MIT’s vice president for research and the E. A. Griswold Professor of Geophysics. “I am grateful to Applied Materials for its investment in this vision. The impact of the new toolset will ripple across MIT and throughout Massachusetts, the region, and the nation.”

Applied Materials is the world’s largest supplier of equipment for manufacturing semiconductors, displays, and other advanced electronics. The company will provide at MIT.nano several state-of-the-art process tools capable of supporting 150 and 200mm wafers and will enhance and upgrade an existing tool owned by MIT. In addition to assisting MIT.nano in the day-to-day operation and maintenance of the equipment, Applied engineers will develop new process capabilities that will benefit researchers and students from MIT and beyond.

“Chips are becoming increasingly complex, and there is tremendous need for continued advancements in 200mm devices, particularly compound semiconductors like silicon carbide and gallium nitride,” says Aninda Moitra, corporate vice president and general manager of Applied Materials’ ICAPS Business. “Applied is excited to team with MIT.nano to create a unique, open-access site in the U.S. where the chip ecosystem can collaborate to accelerate innovation. Our engagement with MIT expands Applied’s university innovation network and furthers our efforts to reduce the time and cost of commercializing new technologies while strengthening the pipeline of future semiconductor industry talent.”

The NEMC Hub, managed by the Massachusetts Technology Collaborative (MassTech), will allocate $7.7 million to enable the installation of the tools. The NEMC is the regional “hub” that connects and amplifies the capabilities of diverse organizations from across New England, plus New Jersey and New York. The U.S. Department of Defense (DoD) selected the NEMC Hub as one of eight Microelectronics Commons Hubs and awarded funding from the CHIPS and Science Act to accelerate the transition of critical microelectronics technologies from lab-to-fab, spur new jobs, expand workforce training opportunities, and invest in the region’s advanced manufacturing and technology sectors.

The Microelectronics Commons program is managed at the federal level by the Office of the Under Secretary of Defense for Research and Engineering and the Naval Surface Warfare Center, Crane Division, and facilitated through the National Security Technology Accelerator (NSTXL), which organizes the execution of the eight regional hubs located across the country. The announcement of the public sector support for the project was made at an event attended by leaders from the DoD and NSTXL during a site visit to meet with NEMC Hub members.

“The installation and operation of these tools at MIT.nano will have a direct impact on the members of the NEMC Hub, the Massachusetts and Northeast regional economy, and national security. This is what the CHIPS and Science Act is all about,” says Ben Linville-Engler, deputy director at the MassTech Collaborative and the interim director of the NEMC Hub. “This is an essential investment by the NEMC Hub to meet the mission of the Microelectronics Commons.”

MIT.nano is a 200,000 square-foot facility located in the heart of the MIT campus with pristine, class-100 cleanrooms capable of accepting these advanced tools. Its open-access model means that MIT.nano’s toolsets and laboratories are available not only to the campus, but also to early-stage R&D by researchers from other academic institutions, nonprofit organizations, government, and companies ranging from Fortune 500 multinationals to local startups. Vladimir Bulović, faculty director of MIT.nano, says he expects the new equipment to come online in early 2025.

“With vital funding for installation from NEMC and after a thorough and productive planning process with Applied Materials, MIT.nano is ready to install this toolset and integrate it into our expansive capabilities that serve over 1,100 researchers from academia, startups, and established companies,” says Bulović, who is also the Fariborz Maseeh Professor of Emerging Technologies in MIT’s Department of Electrical Engineering and Computer Science. “We’re eager to add these powerful new capabilities and excited for the new ideas, collaborations, and innovations that will follow.”

As part of its arrangement with MIT.nano, Applied Materials will join the MIT.nano Consortium, an industry program comprising 12 companies from different industries around the world. With the contributions of the company’s technical staff, Applied Materials will also have the opportunity to engage with MIT’s intellectual centers, including continued membership with the Microsystems Technology Laboratories.

Using a virus-like delivery particle made from DNA, researchers from MIT and the Ragon Institute of MGH, MIT, and Harvard have created a vaccine that can induce a strong antibody response against SARS-CoV-2.

The vaccine, which has been tested in mice, consists of a DNA scaffold that carries many copies of a viral antigen. This type of vaccine, known as a particulate vaccine, mimics the structure of a virus. Most previous work on particulate vaccines has relied on protein scaffolds, but the proteins used in those vaccines tend to generate an unnecessary immune response that can distract the immune system from the target.

In the mouse study, the researchers found that the DNA scaffold does not induce an immune response, allowing the immune system to focus its antibody response on the target antigen.

“DNA, we found in this work, does not elicit antibodies that may distract away from the protein of interest,” says Mark Bathe, an MIT professor of biological engineering. “What you can imagine is that your B cells and immune system are being fully trained by that target antigen, and that’s what you want — for your immune system to be laser-focused on the antigen of interest.”

This approach, which strongly stimulates B cells (the cells that produce antibodies), could make it easier to develop vaccines against viruses that have been difficult to target, including HIV and influenza, as well as SARS-CoV-2, the researchers say. Unlike T cells, which are stimulated by other types of vaccines, these B cells can persist for decades, offering long-term protection.

“We’re interested in exploring whether we can teach the immune system to deliver higher levels of immunity against pathogens that resist conventional vaccine approaches, like flu, HIV, and SARS-CoV-2,” says Daniel Lingwood, an associate professor at Harvard Medical School and a principal investigator at the Ragon Institute. “This idea of decoupling the response against the target antigen from the platform itself is a potentially powerful immunological trick that one can now bring to bear to help those immunological targeting decisions move in a direction that is more focused.”

Bathe, Lingwood, and Aaron Schmidt, an associate professor at Harvard Medical School and principal investigator at the Ragon Institute, are the senior authors of the paper, which appears today in Nature Communications. The paper’s lead authors are Eike-Christian Wamhoff, a former MIT postdoc; Larance Ronsard, a Ragon Institute postdoc; Jared Feldman, a former Harvard University graduate student; Grant Knappe, an MIT graduate student; and Blake Hauser, a former Harvard graduate student. 

Mimicking viruses

Particulate vaccines usually consist of a protein nanoparticle, similar in structure to a virus, that can carry many copies of a viral antigen. This high density of antigens can lead to a stronger immune response than traditional vaccines because the body sees it as similar to an actual virus. Particulate vaccines have been developed for a handful of pathogens, including hepatitis B and human papillomavirus, and a particulate vaccine for SARS-CoV-2 has been approved for use in South Korea.

These vaccines are especially good at activating B cells, which produce antibodies specific to the vaccine antigen.

“Particulate vaccines are of great interest for many in immunology because they give you robust humoral immunity, which is antibody-based immunity, which is differentiated from the T-cell-based immunity that the mRNA vaccines seem to elicit more strongly,” Bathe says.

A potential drawback to this kind of vaccine, however, is that the proteins used for the scaffold often stimulate the body to produce antibodies targeting the scaffold. This can distract the immune system and prevent it from launching as robust a response as one would like, Bathe says.

“To neutralize the SARS-CoV-2 virus, you want to have a vaccine that generates antibodies toward the receptor binding domain portion of the virus’ spike protein,” he says. “When you display that on a protein-based particle, what happens is your immune system recognizes not only that receptor binding domain protein, but all the other proteins that are irrelevant to the immune response you’re trying to elicit.”

Another potential drawback is that if the same person receives more than one vaccine carried by the same protein scaffold, for example, SARS-CoV-2 and then influenza, their immune system would likely respond right away to the protein scaffold, having already been primed to react to it. This could weaken the immune response to the antigen carried by the second vaccine.

“If you want to apply that protein-based particle to immunize against a different virus like influenza, then your immune system can be addicted to the underlying protein scaffold that it’s already seen and developed an immune response toward,” Bathe says. “That can hypothetically diminish the quality of your antibody response for the actual antigen of interest.”

As an alternative, Bathe’s lab has been developing scaffolds made using DNA origami, a method that offers precise control over the structure of synthetic DNA and allows researchers to attach a variety of molecules, such as viral antigens, at specific locations.

In a 2020 study, Bathe and Darrell Irvine, an MIT professor of biological engineering and of materials science and engineering, showed that a DNA scaffold carrying 30 copies of an HIV antigen could generate a strong antibody response in B cells grown in the lab. This type of structure is optimal for activating B cells because it closely mimics the structure of nano-sized viruses, which display many copies of viral proteins in their surfaces.

“This approach builds off of a fundamental principle in B-cell antigen recognition, which is that if you have an arrayed display of the antigen, that promotes B-cell responses and gives better quantity and quality of antibody output,” Lingwood says.

“Immunologically silent”

In the new study, the researchers swapped in an antigen consisting of the receptor binding protein of the spike protein from the original strain of SARS-CoV-2. When they gave the vaccine to mice, they found that the mice generated high levels of antibodies to the spike protein but did not generate any to the DNA scaffold.

In contrast, a vaccine based on a scaffold protein called ferritin, coated with SARS-CoV-2 antigens, generated many antibodies against ferritin as well as SARS-CoV-2.

“The DNA nanoparticle itself is immunogenically silent,” Lingwood says. “If you use a protein-based platform, you get equally high titer antibody responses to the platform and to the antigen of interest, and that can complicate repeated usage of that platform because you’ll develop high affinity immune memory against it.”

Reducing these off-target effects could also help scientists reach the goal of developing a vaccine that would induce broadly neutralizing antibodies to any variant of SARS-CoV-2, or even to all sarbecoviruses, the subgenus of virus that includes SARS-CoV-2 as well as the viruses that cause SARS and MERS.

To that end, the researchers are now exploring whether a DNA scaffold with many different viral antigens attached could induce broadly neutralizing antibodies against SARS-CoV-2 and related viruses. 

The research was primarily funded by the National Institutes of Health, the National Science Foundation, and the Fast Grants program.

Want to get middle-school kids excited about science? Let them do their own experiments on MIT.nano’s state-of-the-art microscopes — with guidelines and adult supervision, of course. That was the brainchild of Carl Thrasher and Tao Cai, MIT graduate students who spearheaded the Electron Microscopy Elevating Representation and Growth in Education (EMERGE) program.

Held in November, EMERGE invited 18 eighth-grade students to the pilot event at MIT.nano, an interdisciplinary facility for nanoscale research, to get hands-on experience in microscopy and materials science.

The highlight of the two-hour workshop: Each student explored mystery samples of everyday materials using one of two scanning electron microscopes (SEMs), which scan material samples using a beam of electrons to form an image. Though highly sophisticated, the instruments generated readily understandable data — images of intricate structures in a butterfly wing or a strand of hair, for example.

The students had an immediate, tangible sense of success, says Thrasher, from MIT’s Department of Materials Science and Engineering (DMSE). He led the program along with Cai, also from DMSE, and Collette Gordon, a grad student in the Department of Chemistry.

“This experience helped build a sense of agency and autonomy around this area of science, nurturing budding self-confidence among the students,” Thrasher says. “We didn’t give the students instructions, just empowered them to solve problems. When you don’t tell them the solution, you get really surprised with what they come up with.”

Unlocking interest in the infinitesimal

The students were part of a multi-year science and engineering exploration program called MITES Saturdays, run by MIT Introduction to Technology, Engineering, and Science, or MITES. A team of volunteers was on hand to help students follow the guidance set out by Thrasher, ensuring the careful handling of the SEMs — worth roughly $500,000 each.

MITES Saturdays program administrator Lynsey Ford was thrilled to observe the students’ autonomous exploration and enthusiasm.

“Our students got to meet real scientists who listened to them, cared about the questions they were asking, and welcomed them into a world of science,” Ford says. “A supportive learning environment can be just as powerful for science discovery as a half-million-dollar microscope.”

The pilot workshop was the first step for Thrasher and his team in their goal to build EMERGE into a program with broad impact, engaging middle-to-high school students from a variety of communities.

The partnership with MITES Saturdays is crucial for this endeavor, says Thrasher, providing a platform to reach a wider audience. “Seeing students from diverse backgrounds participating in EMERGE reinforces the profound difference science education can have.”

MITES Saturdays students are high-achieving Massachusetts seventh through 12th graders from Boston, MIT’s hometown of Cambridge, and nearby Lawrence.

“The majority of students who participate in our programs would be the first person in their family to go to college. A lot of them are from families balancing some sort of financial hardship, and from populations that are historically underrepresented in STEM,” Ford says.

Experienced SEM users set up the instruments and prepared test samples so students could take turns exploring specimens such as burrs, butterfly wings, computer chips, hair, and pollen by operating the microscope to adjust magnification, focus, and stage location.

Students left the EMERGE event with copies of the electron microscope images they generated. Thrasher hopes they will use these materials in follow-up projects, ideally integrating them into existing school curricula so students can share their experiences.

EMERGE co-director Cai says students were excited with their experimentation, both in being able to access such high-end equipment and in seeing what materials like Velcro look like under an SEM (spoiler alert: it’s spaghetti).

“We definitely saw a spark,” Cai says. “The subject matter was complex, but the students always wanted to know more.” And the after-program feedback was positive, with most saying the experience was fun and challenging. The volunteers noted how engaged the students were with the SEMs and subject matter. One volunteer overheard students say, “I felt like a real scientist!”

Inspiring tomorrow’s scientists

EMERGE is based on the Scanning Electron Microscopy Educators program, a long-running STEM outreach program started in 1991 by the Air Force Research Laboratory and adopted by Michigan State University. As an Air Force captain stationed at Wright-Patterson Air Force Base in Ohio, Thrasher participated in the program as a volunteer SEM expert.

“I thought it was an incredible opportunity for young students and wanted to bring it here to MIT,” he says.

The pilot was made possible thanks to support from the MITES Saturdays team and the Graduate Materials Council (GMC), the DMSE graduate student organization. Cai and DMSE grad student Jessica Dong, who are both GMC outreach chairs, helped fund, organize, and coordinate the event.

The MITES Saturdays students included reflections on their experience with the SEMs in their final presentations at the MITES Fall Symposium in November.

“My favorite part of the semester was using the SEM as it introduced me to microscopy at the level of electrons,” said one student.

“Our students had an incredible time with the EMERGE team. We’re excited about the possibility of future partnerships with MIT.nano and other departments at MIT, giving our scholars exposure to the breadth of opportunities as future scientists,” says Eboney Hearn, MITES executive director.

With the success of the pilot, the EMERGE team is looking to offer more programs to the MITES students in the spring. Anna Osherov is excited to give students more access to the cumulative staff knowledge and cutting-edge equipment at MIT.nano, which opened in 2018. Osherov is associate director for Characterization.nano, a shared experimental facility for advanced imaging and analysis.

“Our mission is to support mature researchers — and to help inspire the future PhDs and professors who will come to MIT to learn, research, and innovate,” Osherov says. “Designing and offering such programs, aimed at fostering natural curiosity and creativity of young minds, has a tremendous long-term benefit to our society. We can raise tomorrow’s generation in a better way.”

For her part, Ford is still coasting on the students’ excitement. “They come into the program so curious and hungry for knowledge. They remind me every day how amazing the world is.”

An intricate, honeycomb-like structure of struts and beams could withstand a supersonic impact better than a solid slab of the same material. What’s more, the specific structure matters, with some being more resilient to impacts than others.

That’s what MIT engineers are finding in experiments with microscopic metamaterials — materials that are intentionally printed, assembled, or otherwise engineered with microscopic architectures that give the overall material exceptional properties.

In a study appearing today in the Proceedings of the National Academy of Sciences, the engineers report on a new way to quickly test an array of metamaterial architectures and their resilience to supersonic impacts.

In their experiments, the team suspended tiny printed metamaterial lattices between microscopic support structures, then fired even tinier particles at the materials, at supersonic speeds. With high-speed cameras, the team then captured images of each impact and its aftermath, with nanosecond precision.

Their work has identified a few metamaterial architectures that are more resilient to supersonic impacts compared to their entirely solid, nonarchitected counterparts. The researchers say the results they observed at the microscopic level can be extended to comparable macroscale impacts, to predict how new material structures across length scales will withstand impacts in the real world.

“What we’re learning is, the microstructure of your material matters, even with high-rate deformation,” says study author Carlos Portela, the Brit and Alex d’Arbeloff Career Development Professor in Mechanical Engineering at MIT. “We want to identify impact-resistant structures that can be made into coatings or panels for spacecraft, vehicles, helmets, and anything that needs to be lightweight and protected.”

Other authors on the study include first author and MIT graduate student Thomas Butruille, and Joshua Crone of DEVCOM Army Research Laboratory.

Pure impact

The team’s new high-velocity experiments build off their previous work, in which the engineers tested the resilience of an ultralight, carbon-based material. That material, which was thinner than the width of a human hair, was made from tiny struts and beams of carbon, which the team printed and placed on a glass slide. They then fired microparticles toward the material, at velocities exceeding the speed of sound.  

Those supersonic experiments revealed that the microstructured material withstood the high-velocity impacts, sometimes deflecting the microparticles and other times capturing them.

“But there were many questions we couldn’t answer because we were testing the materials on a substrate, which may have affected their behavior,” Portela says.

In their new study, the researchers developed a way to test freestanding metamaterials, to observe how the materials withstand impacts purely on their own, without a backing or supporting substrate.

In their current setup, the researchers suspend a metamaterial of interest between two microscopic pillars made from the same base material. Depending on the dimensions of the metamaterial being tested, the researchers calculate how far apart the pillars must be in order to support the material at either end while allowing the material to respond to any impacts, without any influence from the pillars themselves.

“This way, we ensure that we’re measuring the material property and not the structural property,” Portela says.

Once the team settled on the pillar support design, they moved on to test a variety of metamaterial architectures. For each architecture, the researchers first printed the supporting pillars on a small silicon chip, then continued printing the metamaterial as a suspended layer between the pillars.

“We can print and test hundreds of these structures on a single chip,” Portela says.

Punctures and cracks

The team printed suspended metamaterials that resembled intricate honeycomb-like cross-sections. Each material was printed with a specific three-dimensional microscopic architecture, such as a precise scaffold of repeating octets, or more faceted polygons. Each repeated unit measured as small as a red blood cell. The resulting metamaterials were thinner than the width of a human hair.

The researchers then tested each metamaterial’s impact resilience by firing glass microparticles toward the structures, at speeds of up to 900 meters per second (more than 2,000 miles per hour) — well within the supersonic range. They caught each impact on camera and studied the resulting images, frame by frame, to see how the projectiles penetrated each material. Next, they examined the materials under a microscope and compared each impact’s physical aftermath.

“In the architected materials, we saw this morphology of small cylindrical craters after impact,” Portela says. “But in solid materials, we saw a lot of radial cracks and bigger chunks of material that were gouged out.”

Overall, the team observed that the fired particles created small punctures in the latticed metamaterials, and the materials nevertheless stayed intact. In contrast, when the same particles were fired at the same speeds into solid, nonlatticed materials of equal mass, they created large cracks that quickly spread, causing the material to crumble. The microstructured materials, therefore, were more efficient in resisting supersonic impacts as well as protecting against multiple impact events. And in particular, materials that were printed with the repeating octets appeared to be the most hardy.

“At the same velocity, we see the octet architecture is harder to fracture, meaning that the metamaterial, per unit mass, can withstand impacts up to twice as much as the bulk material,” Portela says. “This tells us that there are some architectures that can make a material tougher which can offer better impact protection.”

Going forward, the team plans to use the new rapid testing and analysis method to identify new metamaterial designs, in hopes of tagging architectures that can be scaled up to stronger and lighter protective gear, garments, coatings, and paneling.

“What I’m most excited about is showing we can do a lot of these extreme experiments on a benchtop,” Portela says. “This will significantly accelerate the rate at which we can validate new, high-performing, resilient materials.”

This work was funded, in part, by DEVCOM ARL Army Research Office through the MIT Institute for Soldier Nanotechnologies (ISN), and carried out, in part, using ISN’s and MIT.nano’s facilities. 

Retroviruses cannot replicate on their own — they must insert their genetic code into the DNA of a host and exploit the host cell's resources to make more copies of themselves, furthering infection. Some retroviruses only infect cells as they divide, when the nuclear envelope that protects the host's genetic material breaks down, making it easily accessible. HIV-1 is a type of retrovirus, called a lentivirus, that can infect non-dividing cells.

HIV-1 delivers its genome into the nucleus by packaging it into a large, cone-shaped structure called a capsid — but the exact mechanism has remained elusive for decades. Travel through the nuclear envelope occurs through, and is regulated by, nuclear pores, doughnut-shaped protein assemblies. Human cells have about 2,000 nuclear pores perforating the nuclear envelope. Some earlier evidence suggested that the capsid remains intact during its delivery into the nucleus — but this created a dimensional conundrum. The cone-shaped HIV-1 capsid is about 120 nanometers long and 60 nm wide — too large, researchers thought, to fit through the opening of the nuclear pore, measured at only 43 nm wide.

Members of the Schwartz Lab at MIT, in the Department of Biology, became interested in this question when a postdoc in the lab used cryo-electron tomography, slicing up sections of frozen cells to examine structures, to show that nuclear pores in the nuclear envelope are larger than 43nm. They deflate and shrink, it turns out, when removed from their native conditions. In native conditions, the nuclear pore complex is about 60nm wide — wide enough to accommodate the HIV-1 capsid.

Knowing that it could fit, a question remained: How can the capsid navigate the dense mesh of spaghetti-like proteins that act like a sieve in the nuclear pore channel? That spaghetti-like mesh allows small cargo to diffuse through, but prevents large cargo from entering unless it is escorted by proteins called nuclear transport receptors.

In an open-access paper published today in Nature, researchers present evidence that the HIV-1 capsid mimics the cell's transport receptors to traverse the nuclear pore.

To support that conclusion, the researchers showed three things in vitro: that an HIV-1 capsid can deliver cargo through a nuclear pore analog; that the capsid can interact with the sieve of proteins in the nuclear pore channel; and that the capsid targets the nuclear pore in the absence of native transport proteins.

Nuclear transport receptors escort large cargo through the nuclear pore by “batting away” the spaghetti-like mesh of proteins inside the channel — like someone holding your hand and guiding you across a crowded dance floor. The HIV-1 capsid interacts with the spaghetti-like proteins, but its purpose is more like a Trojan horse — the capsid encapsulates the viral cargo, protecting it from detection in the cytoplasm and as it enters the nuclear pore complex.

"What's really amazing about cells is that they are incredibly complex. What's really difficult about studying cells is that they are incredibly complex," jokes co-first author Erika Weiskopf, a graduate student in the Schwartz lab. "Biochemists are constantly trying to find ways to study their system in a simplified context, but still give it a flavor of cell biology."

To do that, the Schwartz lab collaborated with Dirk Görlich, the director of cellular logistics at the Max Planck Institute for Multidisciplinary Sciences. Görlich is a co-senior author on the paper with MIT’s Boris Magasanik Professor of Biology Thomas Schwartz. Görlich's lab has produced concentrated droplets of the spaghetti-like proteins found inside the nuclear pore, and those droplets allow and exclude cargo the same way a nuclear pore will. In experiments, fluorescently-labeled cargo did not enter the droplets, but fluorescently-labeled cargo packaged in an HIV-1 capsid was delivered. This indicated that the capsid could deliver cargo through a nuclear pore. 

Using a biophysical binding assay, the researchers also showed that the HIV-1 capsid interacts with the proteins inside the channel. Different spaghetti-like proteins are found in different channel sections, such as at the cytoplasmic side's entrance or only inside the channel; there are 10 such proteins in human cells. The capsid is a promiscuous binder — it can interact with all the spaghetti-like proteins found in the channel.

The capsid can target the nuclear pore complex even without the cell's transport receptors, indicating that it is not commandeering native transport receptors to find and enter the nuclear pore. The team used a classic assay in the nucleocytoplasmic transport field to collect this evidence: When cells are treated with digitonin, their membranes become porous. Everything in the cytoplasm will leak out of the cells, but the nuclear envelope will remain intact. Despite the absence of native proteins, the capsid was attracted to the nuclear pore complex, a behavior indicative of a nuclear transport receptor.

Although the capsid behaves like a nuclear transport receptor to penetrate the nuclear pore, it is fundamentally different. A transport receptor doesn't need to conceal material for delivery the way the capsid does to avoid detection.

These findings open new lines of inquiry for what the nuclear pore complex is capable of accommodating.

"The HIV-1 capsid is one of the largest things that we now know can go through the nuclear pore complex intact," Weiskopf says. "It raises all kinds of questions — what other things could be going through the pore that we thought was impossible?"

Schwartz said another question is whether all of the 2,000 nuclear pores in human cells are identical or whether there is something that makes certain pores more amenable to allowing the capsid through.

The capsid is also known to be unusually elastic, a property that may be key for passage through the pore. Another interesting question for the field is whether the cone-shaped capsid gains entry into the pore by squeezing through.

Although the team has shown that the capsid can enter the pore, what happens at the other end of the channel is still unknown — whether the capsid fully or partially enters the nucleus or breaks down inside the channel. Weiskopf is working on perturbing parts of the capsid or the spaghetti-like proteins to learn more about which interactions are most important for successful capsid entry.

Although these results have expanded our understanding of the nuclear pore, much remains unknown, both for HIV-1 infection and for the transport process through the nuclear pore complex.  

"The nuclear pore is such an important element of cell biology, we thought it would be interesting to understand it better — and that's how we figured out that the pore is much bigger than we anticipated," Schwartz says. "We will certainly try to see whether we can understand the mechanism of HIV-1 infection, how the capsid is released on the other side of the channel, and what factors are important there — and to what extent you can manipulate it or influence it for therapeutic applications."

This research was carried out, in part, using MIT.nano facilities.

Tumors constantly shed DNA from dying cells, which briefly circulates in the patient’s bloodstream before it is quickly broken down. Many companies have created blood tests that can pick out this tumor DNA, potentially helping doctors diagnose or monitor cancer or choose a treatment.

The amount of tumor DNA circulating at any given time, however, is extremely small, so it has been challenging to develop tests sensitive enough to pick up that tiny signal. A team of researchers from MIT and the Broad Institute of MIT and Harvard has now come up with a way to significantly boost that signal, by temporarily slowing the clearance of tumor DNA circulating in the bloodstream.

The researchers developed two different types of injectable molecules that they call “priming agents,” which can transiently interfere with the body’s ability to remove circulating tumor DNA from the bloodstream. In a study of mice, they showed that these agents could boost DNA levels enough that the percentage of detectable early-stage lung metastases leapt from less than 10 percent to above 75 percent.

This approach could enable not only earlier diagnosis of cancer, but also more sensitive detection of tumor mutations that could be used to guide treatment. It could also help improve detection of cancer recurrence.

“You can give one of these agents an hour before the blood draw, and it makes things visible that previously wouldn’t have been. The implication is that we should be able to give everybody who’s doing liquid biopsies, for any purpose, more molecules to work with,” says Sangeeta Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and of Electrical Engineering and Computer Science at MIT, and a member of MIT’s Koch Institute for Integrative Cancer Research and the Institute for Medical Engineering and Science.

Bhatia is one of the senior authors of the new study, along with J. Christopher Love, the Raymond A. and Helen E. St. Laurent Professor of Chemical Engineering at MIT and a member of the Koch Institute and the Ragon Institute of MGH, MIT, and Harvard and Viktor Adalsteinsson, director of the Gerstner Center for Cancer Diagnostics at the Broad Institute.

Carmen Martin-Alonso PhD ’23, MIT and Broad Institute postdoc Shervin Tabrizi, and Broad Institute scientist Kan Xiong are the lead authors of the paper, which appears today in Science.

Better biopsies

Liquid biopsies, which enable detection of small quantities of DNA in blood samples, are now used in many cancer patients to identify mutations that could help guide treatment. With greater sensitivity, however, these tests could become useful for far more patients. Most efforts to improve the sensitivity of liquid biopsies have focused on developing new sequencing technologies to use after the blood is drawn.

While brainstorming ways to make liquid biopsies more informative, Bhatia, Love, Adalsteinsson, and their trainees came up with the idea of trying to increase the amount of DNA in a patient’s bloodstream before the sample is taken.

“A tumor is always creating new cell-free DNA, and that’s the signal that we’re attempting to detect in the blood draw. Existing liquid biopsy technologies, however, are limited by the amount of material you collect in the tube of blood,” Love says. “Where this work intercedes is thinking about how to inject something beforehand that would help boost or enhance the amount of signal that is available to collect in the same small sample.”

The body uses two primary strategies to remove circulating DNA from the bloodstream. Enzymes called DNases circulate in the blood and break down DNA that they encounter, while immune cells known as macrophages take up cell-free DNA as blood is filtered through the liver.

The researchers decided to target each of these processes separately. To prevent DNases from breaking down DNA, they designed a monoclonal antibody that binds to circulating DNA and protects it from the enzymes.

“Antibodies are well-established biopharmaceutical modalities, and they’re safe in a number of different disease contexts, including cancer and autoimmune treatments,” Love says. “The idea was, could we use this kind of antibody to help shield the DNA temporarily from degradation by the nucleases that are in circulation? And by doing so, we shift the balance to where the tumor is generating DNA slightly faster than is being degraded, increasing the concentration in a blood draw.”

The other priming agent they developed is a nanoparticle designed to block macrophages from taking up cell-free DNA. These cells have a well-known tendency to eat up synthetic nanoparticles.

“DNA is a biological nanoparticle, and it made sense that immune cells in the liver were probably taking this up just like they do synthetic nanoparticles. And if that were the case, which it turned out to be, then we could use a safe dummy nanoparticle to distract those immune cells and leave the circulating DNA alone so that it could be at a higher concentration,” Bhatia says.

Earlier tumor detection

The researchers tested their priming agents in mice that received transplants of cancer cells that tend to form tumors in the lungs. Two weeks after the cells were transplanted, the researchers showed that these priming agents could boost the amount of circulating tumor DNA recovered in a blood sample by up to 60-fold.

Once the blood sample is taken, it can be run through the same kinds of sequencing tests now used on liquid biopsy samples. These tests can pick out tumor DNA, including specific sequences used to determine the type of tumor and potentially what kinds of treatments would work best.

Early detection of cancer is another promising application for these priming agents. The researchers found that when mice were given the nanoparticle priming agent before blood was drawn, it allowed them to detect circulating tumor DNA in blood of 75 percent of the mice with low cancer burden, while none were detectable without this boost.

“One of the greatest hurdles for cancer liquid biopsy testing has been the scarcity of circulating tumor DNA in a blood sample,” Adalsteinsson says. “It’s thus been encouraging to see the magnitude of the effect we’ve been able to achieve so far and to envision what impact this could have for patients.”

After either of the priming agents are injected, it takes an hour or two for the DNA levels to increase in the bloodstream, and then they return to normal within about 24 hours.

“The ability to get peak activity of these agents within a couple of hours, followed by their rapid clearance, means that someone could go into a doctor’s office, receive an agent like this, and then give their blood for the test itself, all within one visit,” Love says. “This feature bodes well for the potential to translate this concept into clinical use.”

The researchers have launched a company called Amplifyer Bio that plans to further develop the technology, in hopes of advancing to clinical trials.

“A tube of blood is a much more accessible diagnostic than colonoscopy screening or even mammography,” Bhatia says. “Ultimately, if these tools really are predictive, then we should be able to get many more patients into the system who could benefit from cancer interception or better therapy.”

The research was funded by the Koch Institute Support (core) Grant from the National Cancer Institute, the Marble Center for Cancer Nanomedicine, the Gerstner Family Foundation, the Ludwig Center at MIT, the Koch Institute Frontier Research Program via the Casey and Family Foundation, and the Bridge Project, a partnership between the Koch Institute and the Dana-Farber/Harvard Cancer Center.

MIT.nano has announced that Shell, a global group of energy and petrochemical companies, has joined the MIT.nano Consortium.

“With an international perspective on the world’s energy challenges, Shell is an exciting addition to the MIT.nano Consortium,” says Vladimir Bulović, the founding faculty director of MIT.nano and the Fariborz Maseeh (1990) Professor of Emerging Technologies. “The quest to build a sustainable energy future will require creative thinking backed by broad and deep expertise that our Shell colleagues bring. They will be insightful collaborators for the MIT community and for our member companies as we work together to explore innovative technology strategies.”

Founded in 1907 when Shell Transport and Trading Co. merged with Royal Dutch, Shell has more than a century’s worth of experience in the exploration, production, refining, and marketing of oil and natural gas and the manufacturing and marketing of chemicals. Operating in over 70 countries, Shell has set a target to become a net-zero emissions energy business by 2050. To achieve this, Shell is supporting developments of low-carbon energy solutions such as biofuels, hydrogen, charging for electric vehicles, and electricity generated by solar and wind power.

“In line with our Powering Progress strategy, our research efforts to become a net-zero emission energy company by 2050 will require intense collaboration with academic leaders across a wide range of disciplines,” says Rolf van Benthem, Shell’s chief scientist for materials science. “We look forward to engaging with the top-notch PIs [principal investigators] at MIT.nano who excel in fields like materials design and nanoscale characterization for use in energy applications and carbon utilization. Together we can work on truly sustainable solutions for our society.”

Shell has been engaged in research collaborations with MIT since 2002 and is a founding member of the MIT Energy Initiative (MITEI). Recent MIT projects supported by Shell include an urban building energy model with the MIT Sustainable Design Laboratory that explores energy-saving building retrofits, a study of the role and impact of hydrogen-based technology pathways with MITEI, and a materials science and engineering project to design better batteries for electric vehicles.

The MIT.nano Consortium is a platform for academia-industry collaboration centered around research and innovation emerging from nanoscale science and engineering at MIT. Through activities that include quarterly industry consortium meetings, Shell will gain insight into the work of MIT.nano’s community of users and provide advice to help guide and advance nanoscale innovations at MIT alongside the 11 other consortium companies:

• Analog Devices;
• Draper;
• Edwards;
• Fujikura;
• IBM Research;
• Lam Research;
• NC;
• NEC;
• Raith;
• UpNano; and
• Viavi Solutions.

MIT.nano continues to welcome new companies as sustaining members. For more details, visit the MIT.nano Consortium page.

On Nov. 7, a team from the Marble Center for Cancer Nanomedicine at MIT showed a Washington audience several examples of how nanotechnologies developed at the Institute can transform the detection and treatment of cancer and other diseases.

The team was one of 40 innovative groups featured at “American Possibilities: A White House Demo Day.” Technology on view spanned energy, artificial intelligence, climate, and health, highlighting advancements that contribute to building a better future for all Americans.

Participants included President Joe Biden, Biden-Harris administration leaders and White House staff, members of Congress, federal R&D funding agencies, scientists and engineers, academics, students, and science and technology industry innovators. The event holds special significance for MIT as eight years ago, MIT's Computer Science and Artificial Intelligence Laboratory participated in the last iteration of the White House Demo Day under President Barack Obama.

“It was truly inspirational hearing from experts from all across the government, the private sector, and academia touching on so many fields,” said President Biden of the event. “It was a reminder, at least for me, of what I’ve long believed — that America can be defined by a single word... possibilities.”

Launched in 2016, the Marble Center for Cancer Nanomedicine was established at the Koch Institute for Integrative Research at MIT to serve as a hub for miniaturized biomedical technologies, especially those that address grand challenges in cancer detection, treatment, and monitoring. The center convenes Koch Institute faculty members Sangeeta Bhatia, Paula Hammond, Robert Langer, Angela Belcher, Darrell Irvine, and Daniel Anderson to advance nanomedicine, as well as to facilitate collaboration with industry partners, including Alloy Therapeutics, Danaher Corp., Fujifilm, and Sanofi. 

Ana Jaklenec, a principal research scientist at the Koch Institute, highlighted several groundbreaking technologies in vaccines and disease diagnostics and treatment at the event. Jaklenec gave demonstrations from projects from her research group, including novel vaccine formulations capable of releasing a dozen booster doses pulsed over predetermined time points, microneedle vaccine technologies, and nutrient delivery technologies for precise control over microbiome modulation and nutrient absorption.

Jaklenec describes the event as “a wonderful opportunity to meet our government leaders and policymakers and see their passion for curing cancer. But it was especially moving to interact with people representing diverse communities across the United States and hear their excitement for how our technologies could positively impact their communities.”

Jeremy Li, a former MIT postdoc, presented a technology developed in the Belcher laboratory and commercialized by the spinout Cision Vision. The startup is developing a new approach to visualize lymph nodes in real time without any injection or radiation. The shoebox-sized device was also selected as part of Time Magazine’s Best Inventions of 2023 and is currently being used in a dozen hospitals across the United States.

“It was a proud moment for Cision Vision to be part of this event and discuss our recent progress in the field of medical imaging and cancer care,” says Li, who is a co-founder and the CEO of CisionVision. “It was a humbling experience for us to hear directly from patient advocates and cancer survivors at the event. We feel more inspired than ever to bring better solutions for cancer care to patients around the world.”

Other technologies shown at the event included new approaches such as a tortoise-shaped pill designed to enhance the efficacy of oral medicines, a miniature organ-on-a-chip liver device to predict drug toxicity and model liver disease, and a wireless bioelectronic device that provides oxygen for cell therapy applications and for the treatment of chronic disease.

“The feedback from the organizers and the audience at the event has been overwhelmingly positive,” says Tarek Fadel, who led the team’s participation at the event. “Navigating the demonstration space felt like stepping into the future. As a center, we stand poised to engineer transformative tools that will truly make a difference for the future of cancer care.”

Sangeeta Bhatia, the Director of the Marble Center and the John J. and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science, adds: “The showcase of our technologies at the White House Demo Day underscores the transformative impact we aim to achieve in cancer detection and treatment. The event highlights our vision to advance cutting-edge solutions for the benefit of patients and communities worldwide.”

Some Covid-19 vaccines safely and effectively used lipid nanoparticles (LNPs) to deliver messenger RNA to cells. A new MIT study shows that different nanoparticles could be used for a potential Alzheimer’s disease (AD) therapy. In tests in multiple mouse models and with cultured human cells, a newly tailored LNP formulation effectively delivered small interfering RNA (siRNA) to the brain’s microglia immune cells to suppress expression of a protein linked to excessive inflammation in Alzheimer’s disease.

In a prior study, the researchers showed that blocking the consequences of PU.1 protein activity helps to reduce Alzheimer’s disease-related neuroinflammation and pathology. The new open-access results, reported in the journal Advanced Materials, achieves a reduction in inflammation by directly tamping down expression of the Spi1 gene that encodes PU.1. More generally, the new study also demonstrates a new way to deliver RNA to microglia, which have been difficult to target so far.

Study co-senior author Li-Huei Tsai, the Picower professor of neuroscience and director of The Picower Institute for Learning and Memory and Aging Brain Initiative at MIT, says she hypothesized that LNPs might work as a way to bring siRNA into microglia because the cells, which clear waste in the brain, have a strong proclivity to uptake lipid molecules. She discussed this with Robert Langer, the David Koch Institute Professor, who is widely known for his influential work on nanoparticle drug delivery. They decided to test the idea of reducing PU.1 expression with an LNP-delivered siRNA.

“I still remember the day when I asked to meet with Bob to discuss the idea of testing LNPs as a payload to target inflammatory microglia,” says Tsai, a faculty member in the Department of Brain and Cognitive Sciences. “I am very grateful to The JPB Foundation, who supported this idea without any preliminary evidence.”

Langer Lab graduate student Jason Andresen and former Tsai Lab postdoc William Ralvenius led the work and are the study’s co-lead authors. Owen Fenton, a former Langer Lab postdoc who is now an assistant professor at the University of North Carolina’s Eshelman School of Pharmacy, is a co-corresponding author along with Tsai and Langer. Langer is a professor in the departments of Chemical Engineering and Biological Engineering, and the Koch Institute for Integrative Cancer Research.

Perfecting a particle

The simplest way to test whether siRNA could therapeutically suppress PU.1 expression would have been to make use of an already available delivery device, but one of the first discoveries in the study is that none of eight commercially available reagents could safely and effectively transfect cultured human microglia-like cells in the lab.

Instead, the team had to optimize an LNP to do the job. LNPs have four main components; by changing the structures of two of them, and by varying the ratio of lipids to RNA, the researchers were able to come up with seven formulations to try. Importantly, their testing included trying their formulations on cultured microglia that they had induced into an inflammatory state. That state, after all, is the one in which the proposed treatment is needed.

Among the seven candidates, one the team named “MG-LNP” stood out for its especially high delivery efficiency and safety of a test RNA cargo.

What works in a dish sometimes doesn’t work in a living organism, so the team next tested their LNP formulations’ effectiveness and safety in mice. Testing two different methods of injection, into the body or into the cerebrospinal fluid (CSF), they found that injection into the CSF ensured much greater efficacy in targeting microglia without affecting cells in other organs. Among the seven formulations, MG-LNP again proved the most effective at transfecting microglia. Langer said he believes this could potentially open new ways of treating certain brain diseases with nanoparticles someday. 

A targeted therapy

Once they knew MG-LNP could deliver a test cargo to microglia both in human cell cultures and mice, the scientists then tested whether using it to deliver a PU.1-suppressing siRNA could reduce inflammation in microglia. In the cell cultures, a relatively low dose achieved a 42 percent reduction of PU.1 expression (which is good because microglia need at least some PU.1 to live). Indeed, MG-LNP transfection did not cause the cells any harm. It also significantly reduced the transcription of the genes that PU.1 expression increases in microglia, indicating that it can reduce multiple inflammatory markers.

In all these measures, and others, MG-LNP outperformed a commercially available reagent called RNAiMAX that the scientists tested in parallel.

“These findings support the use of MG-LNP-mediated anti-PU.1 siRNA delivery as a potential therapy for neuroinflammatory diseases,” the researchers wrote.

The final set of tests evaluated MG-LNP’s performance delivering the siRNA in two mouse models of inflammation in the brain. In one, mice were exposed to LPS, a molecule that simulates infection and stimulates a systemic inflammation response. In the other model, mice exhibit severe neurodegeneration and inflammation when an enzyme called CDK5 becomes hyperactivated by a protein called p25.

In both models, injection of MG-LNPs carrying the anti-PU.1 siRNA reduced expression of PU.1 and inflammatory markers, much like in the cultured human cells.

“MG-LNP delivery of anti-PU.1 siRNA can potentially be used as an anti-inflammatory therapeutic in mice with systemic inflammation an in the CK-p25 mouse model of AD-like neuroinflammation,” the scientists concluded, calling the results a “proof-of-principle.” More testing will be required before the idea could be tried in human patients.

In addition to Andresen, Ralvenius, Langer, Tsai, and Owen, the paper’s other authors are Margaret Huston, Jay Penney, and Julia Maeve Bonner.

In addition to the The JPB Foundation and The Picower Institute for Learning and Memory, the Robert and Renee Belfer Family, Eduardo Eurnekian, Lester A. Gimpelson, Jay L. and Carroll Miller, the Koch Institute, the Swiss National Science Foundation, and the Alzheimer’s Association provided funding for the study.

“How do we get to making nanomaterials that haven’t been evolved before?” asked Angela Belcher at the 2023 Mildred S. Dresselhaus Lecture at MIT on Nov. 20. “We can use elements that biology has already given us.”

The combined in-person and virtual audience of over 300 was treated to a light-up, 3D model of M13 bacteriophage, a virus that only infects bacteria, complete with a pull-out strand of DNA. Belcher used the feather-boa-like model to show how her research group modifies the M13’s genes to add new DNA and peptide sequences to template inorganic materials.

“I love controlling materials at the nanoscale using biology,” said Belcher, the James Mason Crafts Professor of Biological Engineering, materials science professor, and of the Koch Institute of Integrative Cancer Research at MIT. “We all know if you control materials at the nanoscale and you can start to tune them, then you can have all kinds of different applications.” And the opportunities are indeed vast — from building batteries, fuel cells, and solar cells to carbon sequestration and storage, environmental remediation, catalysis, and medical diagnostics and imaging.

Belcher sprinkled her talk with models and props, lined up on a table at the front of the 10-250 lecture hall, to demonstrate a wide variety of concepts and projects made possible by the intersection of biology and nanotechnology.

Energy storage and environment

“How do you go from a DNA sequence to a functioning battery?” posed Belcher. Grabbing a model of a large carbon nanotube, she explained how her group engineered a phage to pick up carbon nanotubes that would wind all the way around the virus and then fill in with different cathode or anode materials to make nanowires for battery electrodes.

How about using the M13 bacteriophage to improve the environment? Belcher referred to a project by former student Geran Zhang PhD ’19 that proved the virus can be modified for this context, too. He used the phage to template high-surface-area, carbon-based materials that can grab small molecules and break them down, Belcher said, opening a realm of possibilities from cleaning up rivers to developing chemical warfare agents to combating smog.

Belcher’s lab worked with the U.S. Army to produce protective clothing and masks made of these carbon-based virus nanofibers. “We went from five liters in our lab to a thousand liters, then 10,000 liters in the army labs where we’re able to make kilograms of the material,” Belcher said, stressing the importance of being able to test and prototype at scale.

Imaging tools and therapeutics in cancer

In the area of biomedical imaging, Belcher explained, a lot less is known in near-infrared imaging — imaging in wavelengths above 1,000 nanometers — than other imaging techniques, yet with near-infrared scientists can see much deeper inside the body. Belcher’s lab built their own systems to image at these wavelengths. The third generation of this system provides real-time, sub-millimeter optical imaging for guided surgery.

Working with Sangeeta Bhatia, the John J. and Dorothy Wilson Professor of Engineering, Belcher used carbon nanotubes to build imaging tools that find tiny tumors during surgery that doctors otherwise would not be able to see. The tool is actually a virus engineered to carry with it a fluorescent, single-walled carbon nanotube as it seeks out the tumors.

Nearing the end of her talk, Belcher presented a goal: to develop an accessible detection and diagnostic technology for ovarian cancer in five to 10 years.

“We think that we can do it,” Belcher said. She described her students’ work developing a way to scan an entire fallopian tube, as opposed to just one small portion, to find pre-cancer lesions, and talked about the team of MIT faculty, doctors, and researchers working collectively toward this goal.

“Part of the secret of life and the meaning of life is helping other people enjoy the passage of time,” said Belcher in her closing remarks. “I think that we can all do that by working to solve some of the biggest issues on the planet, including helping to diagnose and treat ovarian cancer early so people have more time to spend with their family.”

Honoring Mildred S. Dresselhaus

Belcher was the fifth speaker to deliver the Dresselhaus Lecture, an annual event organized by MIT.nano to honor the late MIT physics and electrical engineering Institute Professor Mildred Dresselhaus. The lecture features a speaker from anywhere in the world whose leadership and impact echo Dresselhaus’s life, accomplishments, and values.

“Millie was and is a huge hero of mine,” said Belcher. “Giving a lecture in Millie’s name is just the greatest honor.”

Belcher dedicated the talk to Dresselhaus, whom she described with an array of accolades — a trailblazer, a genius, an amazing mentor, teacher, and inventor. “Just knowing her was such a privilege,” she said.

Belcher also dedicated her talk to her own grandmother and mother, both of whom passed away from cancer, as well as late MIT professors Susan Lindquist and Angelika Amon, who both died of ovarian cancer.

“I’ve been so fortunate to work with just the most talented and dedicated graduate students, undergraduate students, postdocs, and researchers,” concluded Belcher. “It has been a pure joy to be in partnership with all of you to solve these very daunting problems.”

Photolithography involves manipulating light to precisely etch features onto a surface, and is commonly used to fabricate computer chips and optical devices like lenses. But tiny deviations during the manufacturing process often cause these devices to fall short of their designers’ intentions.

To help close this design-to-manufacturing gap, researchers from MIT and the Chinese University of Hong Kong used machine learning to build a digital simulator that mimics a specific photolithography manufacturing process. Their technique utilizes real data gathered from the photolithography system, so it can more accurately model how the system would fabricate a design.

The researchers integrate this simulator into a design framework, along with another digital simulator that emulates the performance of the fabricated device in downstream tasks, such as producing images with computational cameras. These connected simulators enable a user to produce an optical device that better matches its design and reaches the best task performance.

This technique could help scientists and engineers create more accurate and efficient optical devices for applications like mobile cameras, augmented reality, medical imaging, entertainment, and telecommunications. And because the pipeline of learning the digital simulator utilizes real-world data, it can be applied to a wide range of photolithography systems.

“This idea sounds simple, but the reasons people haven’t tried this before are that real data can be expensive and there are no precedents for how to effectively coordinate the software and hardware to build a high-fidelity dataset,” says Cheng Zheng, a mechanical engineering graduate student who is co-lead author of an open-access paper describing the work. “We have taken risks and done extensive exploration, for example, developing and trying characterization tools and data-exploration strategies, to determine a working scheme. The result is surprisingly good, showing that real data work much more efficiently and precisely than data generated by simulators composed of analytical equations. Even though it can be expensive and one can feel clueless at the beginning, it is worth doing.”

Zheng wrote the paper with co-lead author Guangyuan Zhao, a graduate student at the Chinese University of Hong Kong; and her advisor, Peter T. So, a professor of mechanical engineering and biological engineering at MIT. The research will be presented at the SIGGRAPH Asia Conference.

Printing with light

Photolithography involves projecting a pattern of light onto a surface, which causes a chemical reaction that etches features into the substrate. However, the fabricated device ends up with a slightly different pattern because of miniscule deviations in the light’s diffraction and tiny variations in the chemical reaction.

Because photolithography is complex and hard to model, many existing design approaches rely on equations derived from physics. These general equations give some sense of the fabrication process but can’t capture all deviations specific to a photolithography system. This can cause devices to underperform in the real world.

For their technique, which they call neural lithography, the MIT researchers build their photolithography simulator using physics-based equations as a base, and then incorporate a neural network trained on real, experimental data from a user’s photolithography system. This neural network, a type of machine-learning model loosely based on the human brain, learns to compensate for many of the system’s specific deviations.

The researchers gather data for their method by generating many designs that cover a wide range of feature sizes and shapes, which they fabricate using the photolithography system. They measure the final structures and compare them with design specifications, pairing those data and using them to train a neural network for their digital simulator.

“The performance of learned simulators depends on the data fed in, and data artificially generated from equations can’t cover real-world deviations, which is why it is important to have real-world data,” Zheng says.

Dual simulators

The digital lithography simulator consists of two separate components: an optics model that captures how light is projected on the surface of the device, and a resist model that shows how the photochemical reaction occurs to produce features on the surface.

In a downstream task, they connect this learned photolithography simulator to a physics-based simulator that predicts how the fabricated device will perform on this task, such as how a diffractive lens will diffract the light that strikes it.

The user specifies the outcomes they want a device to achieve. Then these two simulators work together within a larger framework that shows the user how to make a design that will reach those performance goals.

“With our simulator, the fabricated object can get the best possible performance on a downstream task, like the computational cameras, a promising technology to make future cameras miniaturized and more powerful. We show that, even if you use post-calibration to try and get a better result, it will still not be as good as having our photolithography model in the loop,” Zhao adds.

They tested this technique by fabricating a holographic element that generates a butterfly image when light shines on it. When compared to devices designed using other techniques, their holographic element produced a near-perfect butterfly that more closely matched the design. They also produced a multilevel diffraction lens, which had better image quality than other devices.

In the future, the researchers want to enhance their algorithms to model more complicated devices, and also test the system using consumer cameras. In addition, they want to expand their approach so it can be used with different types of photolithography systems, such as systems that use deep or extreme ultraviolet light.

This research is supported, in part, by the U.S. National Institutes of Health, Fujikura Limited, and the Hong Kong Innovation and Technology Fund.

The work was carried out, in part, using MIT.nano’s facilities.

An MIT research team led by Professor Darrell Irvine has developed a novel kind of vaccine adjuvant: a nanoparticle that can help to stimulate the immune system to generate a stronger response to a vaccine. These nanoparticles contain saponin, a compound derived from the bark of the Chilean soapbark tree, along with a molecule called MPLA, each of which helps to activate the immune system.

The adjuvant has been incorporated into an experimental HIV vaccine that has shown promising results in animal studies, and this month, the first human volunteers will receive the vaccine as part of a phase 1 clinical trial run by the Consortium for HIV/AIDS Vaccine Development at the Scripps Research Institute. MIT News spoke with Irvine about why this project required an interdisciplinary approach, and what may lie ahead.

Q: What are the special features of the new nanoparticle adjuvant that help it create a more powerful immune response to vaccination? 

A: Most vaccines, such as the Covid-19 vaccines, are thought to protect us through B cells making protective antibodies. Development of an HIV vaccine has been made challenging by the fact that the B cells that are capable of evolving to produce protective antibodies — called broadly neutralizing antibodies — are very rare in the average person. Vaccine adjuvants are important in this scenario to ensure that when we immunize with an HIV antigen, these rare B cells become activated and get a chance to participate in the immune response.

We particularly discovered that this new adjuvant, which we call SMNP (short for saponin/MPLA nanoparticles), is particularly good at helping more B cells enter germinal centers, the specialized location in lymph nodes where high affinity antibodies are produced. In animal models, SMNP also has shown unique mechanisms of action: Administering antigens with SMNP leads to better antigen delivery to lymph nodes (through increases in lymph flow) and better capture of the antigen by B cells in lymph nodes.

Q: How did your lab, which generally focuses on bioengineering and materials science, end up working on HIV vaccines? What obstacles did you have to overcome in the development of this adjuvant?

A: About 15 years ago, Bruce Walker approached me about getting involved in the HIV vaccine effort, and recruited me to join the Ragon Institute of MGH, MIT, and Harvard as a member of the steering committee. Through the Ragon Institute, I met colleagues in the Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD), and we realized there was a tremendous opportunity to directly contribute to the HIV vaccine challenge, working in partnership with experts in immunogen design, structural biology, and HIV pathogenesis.

As we carried out study after study of SMNP in preclinical animal models, we realized the adjuvant had really amazing effects for promoting anti-HIV antibody responses, and the CHAVD decided this was worth moving forward to testing in humans. A major challenge was transferring the technology out of the lab to synthesize large amounts of the adjuvant under GMP (good manufacturing process) conditions for a clinical trial. The initial contract manufacturing organization (CMO) hired by the consortium to produce SMNP simply couldn’t get a process to work for scalable manufacturing.

Luckily for us, a chemical engineering graduate student, Ivan Pires, whom I co-advise with Paula Hammond, head of MIT’s Department of Chemical Engineering, had developed expertise in one particular processing technique known as tangential flow filtration during his undergraduate training. Leveraging classic chemical engineering skills in thermodynamics and process design, Ivan stepped in and solved the process issues the CMO was facing, allowing the manufacturing to move forward. This to me is what makes MIT great — the ability of our students and postdocs to step up and solve big problems and make big contributions when the need arises.

Q: What other diseases could this approach be useful for? Are there any plans to test it with other types of vaccines?

A: In principle, SMNP may be helpful for any infectious disease vaccine where strong antibody responses are needed. We are currently sharing the adjuvant with about 30 different labs around the world, who are testing it in vaccines against many other pathogens including Epstein-Barr virus, malaria, and influenza. We are hopeful that if SMNP is safe and effective in humans, this will be an adjuvant that can be broadly used in infectious disease trials.

MIT researchers have used 3D printing to produce self-heating microfluidic devices, demonstrating a technique which could someday be used to rapidly create cheap, yet accurate, tools to detect a host of diseases.

Microfluidics, miniaturized machines that manipulate fluids and facilitate chemical reactions, can be used to detect disease in tiny samples of blood or fluids. At-home test kits for Covid-19, for example, incorporate a simple type of microfluidic.

But many microfluidic applications require chemical reactions that must be performed at specific temperatures. These more complex microfluidic devices, which are typically manufactured in a clean room, are outfitted with heating elements made from gold or platinum using a complicated and expensive fabrication process that is difficult to scale up.

Instead, the MIT team used multimaterial 3D printing to create self-heating microfluidic devices with built-in heating elements, through a single, inexpensive manufacturing process. They generated devices that can heat fluid to a specific temperature as it flows through microscopic channels inside the tiny machine.

Their technique is customizable, so an engineer could create a microfluidic that heats fluid to a certain temperature or given heating profile within a specific area of the device. The low-cost fabrication process requires about $2 of materials to generate a ready-to-use microfluidic.

The process could be especially useful in creating self-heating microfluidics for remote regions of developing countries where clinicians may not have access to the expensive lab equipment required for many diagnostic procedures.

“Clean rooms in particular, where you would usually make these devices, are incredibly expensive to build and to run. But we can make very capable self-heating microfluidic devices using additive manufacturing, and they can be made a lot faster and cheaper than with these traditional methods. This is really a way to democratize this technology,” says Luis Fernando Velásquez-García, a principal scientist in MIT’s Microsystems Technology Laboratories (MTL) and senior author of a paper describing the fabrication technique.

He is joined on the paper by lead author Jorge Cañada Pérez-Sala, an electrical engineering and computer science graduate student. The research will be presented at the PowerMEMS Conference this month.

An insulator becomes conductive

This new fabrication process utilizes a technique called multimaterial extrusion 3D printing, in which several materials can be squirted through the printer’s many nozzles to build a device layer by layer. The process is monolithic, which means the entire device can be produced in one step on the 3D printer, without the need for any post-assembly.

To create self-heating microfluidics, the researchers used two materials — a biodegradable polymer known as polylactic acid (PLA) that is commonly used in 3D printing, and a modified version of PLA.

The modified PLA has mixed copper nanoparticles into the polymer, which converts this insulating material into an electrical conductor, Velásquez-García explains. When electrical current is fed into a resistor composed of this copper-doped PLA, energy is dissipated as heat.

“It is amazing when you think about it because the PLA material is a dielectric, but when you put in these nanoparticle impurities, it completely changes the physical properties. This is something we don’t fully understand yet, but it happens and it is repeatable,” he says.

Using a multimaterial 3D printer, the researchers fabricate a heating resistor from the copper-doped PLA and then print the microfluidic device, with microscopic channels through which fluid can flow, directly on top in one printing step. Because the components are made from the same base material, they have similar printing temperatures and are compatible.

Heat dissipated from the resistor will warm fluid flowing through the channels in the microfluidic.

In addition to the resistor and microfluidic, they use the printer to add a thin, continuous layer of PLA that is sandwiched between them. It is especially challenging to manufacture this layer because it must be thin enough so heat can transfer from the resistor to the microfluidic, but not so thin that fluid could leak into the resistor.

The resulting machine is about the size of a U.S. quarter and can be produced in a matter of minutes. Channels about 500 micrometers wide and 400 micrometers tall are threaded through the microfluidic to carry fluid and facilitate chemical reactions.

Importantly, the PLA material is translucent, so fluid in the device remains visible. Many processes rely on visualization or the use of light to infer what is happening during chemical reactions, Velásquez-García explains.

Customizable chemical reactors

The researchers used this one-step manufacturing process to generate a prototype that could heat fluid by 4 degrees Celsius as it flowed between the input and the output. This customizable technique could enable them to make devices which would heat fluids in certain patterns or along specific gradients.

“You can use these two materials to create chemical reactors that do exactly what you want. We can set up a particular heating profile while still having all the capabilities of the microfluidic,” he says.

However, one limitation comes from the fact that PLA can only be heated to about 50 degrees Celsius before it starts to degrade. Many chemical reactions, such as those used for polymerase chain reaction (PCR) tests, require temperatures of 90 degrees or higher. And to precisely control the temperature of the device, researchers would need to integrate a third material that enables temperature sensing.

In addition to tackling these limitations in future work, Velásquez-García wants to print magnets directly into the microfluidic device. These magnets could enable chemical reactions that require particles to be sorted or aligned.

At the same time, he and his colleagues are exploring the use of other materials that could reach higher temperatures. They are also studying PLA to better understand why it becomes conductive when certain impurities are added to the polymer.

“If we can understand the mechanism that is related to the electrical conductivity of PLA, that would greatly enhance the capability of these devices, but it is going to be a lot harder to solve than some other engineering problems,” he adds.

“In Japanese culture, it’s often said that beauty lies in simplicity. This sentiment is echoed by the work of Cañada and Velasquez-Garcia. Their proposed monolithically 3D-printed microfluidic systems embody simplicity and beauty, offering a wide array of potential derivations and applications that we foresee in the future,” says Norihisa Miki, a professor of mechanical engineering at Keio University in Tokyo, who was not involved with this work.

“Being able to directly print microfluidic chips with fluidic channels and electrical features at the same time opens up very exiting applications when processing biological samples, such as to amplify biomarkers or to actuate and mix liquids. Also, due to the fact that PLA degrades over time, one can even think of implantable applications where the chips dissolve and resorb over time,” adds Niclas Roxhed, an associate professor at Sweden’s KTH Royal Institute of Technology, who was not involved with this study.

This research was funded, in part, by the Empiriko Corporation and a fellowship from La Caixa Foundation.

Two-dimensional materials, which are only a few atoms thick, can exhibit some incredible properties, such as the ability to carry electric charge extremely efficiently, which could boost the performance of next-generation electronic devices.

But integrating 2D materials into devices and systems like computer chips is notoriously difficult. These ultrathin structures can be damaged by conventional fabrication techniques, which often rely on the use of chemicals, high temperatures, or destructive processes like etching.

To overcome this challenge, researchers from MIT and elsewhere have developed a new technique to integrate 2D materials into devices in a single step while keeping the surfaces of the materials and the resulting interfaces pristine and free from defects.

Their method relies on engineering surface forces available at the nanoscale to allow the 2D material to be physically stacked onto other prebuilt device layers. Because the 2D material remains undamaged, the researchers can take full advantage of its unique optical and electrical properties.

They used this approach to fabricate arrays of 2D transistors that achieved new functionalities compared to devices produced using conventional fabrication techniques. Their method, which is versatile enough to be used with many materials, could have diverse applications in high-performance computing, sensing, and flexible electronics.

Core to unlocking these new functionalities is the ability to form clean interfaces, held together by special forces that exist between all matter, called van der Waals forces.

However, such van der Waals integration of materials into fully functional devices is not always easy, says Farnaz Niroui, assistant professor of electrical engineering and computer science (EECS), a member of the Research Laboratory of Electronics (RLE), and senior author of a new paper describing the work.

“Van der Waals integration has a fundamental limit,” she explains. “Since these forces depend on the intrinsic properties of the materials, they cannot be readily tuned. As a result, there are some materials that cannot be directly integrated with each other using their van der Waals interactions alone. We have come up with a platform to address this limit to help make van der Waals integration more versatile, to promote the development of 2D-materials-based devices with new and improved functionalities.”

Niroui wrote the paper with lead author Peter Satterthwaite, an electrical engineering and computer science graduate student; Jing Kong, professor of EECS and a member of RLE; and others at MIT, Boston University, National Tsing Hua University in Taiwan, the National Science and Technology Council of Taiwan, and National Cheng Kung University in Taiwan. The research is published today in Nature Electronics.  

Advantageous attraction

Making complex systems such as a computer chip with conventional fabrication techniques can get messy. Typically, a rigid material like silicon is chiseled down to the nanoscale, then interfaced with other components like metal electrodes and insulating layers to form an active device. Such processing can cause damage to the materials.

Recently, researchers have focused on building devices and systems from the bottom up, using 2D materials and a process that requires sequential physical stacking. In this approach, rather than using chemical glues or high temperatures to bond a fragile 2D material to a conventional surface like silicon, researchers leverage van der Waals forces to physically integrate a layer of 2D material onto a device.

Van der Waals forces are natural forces of attraction that exist between all matter. For example, a gecko’s feet can stick to the wall temporarily due to van der Waals forces. Though all materials exhibit a van der Waals interaction, depending on the material, the forces are not always strong enough to hold them together. For instance, a popular semiconducting 2D material known as molybdenum disulfide will stick to gold, a metal, but won’t directly transfer to insulators like silicon dioxide by just coming into physical contact with that surface.

However, heterostructures made by integrating semiconductor and insulating layers are key building blocks of an electronic device. Previously, this integration has been enabled by bonding the 2D material to an intermediate layer like gold, then using this intermediate layer to transfer the 2D material onto the insulator, before removing the intermediate layer using chemicals or high temperatures.

Instead of using this sacrificial layer, the MIT researchers embed the low-adhesion insulator in a high-adhesion matrix. This adhesive matrix is what makes the 2D material stick to the embedded low-adhesion surface, providing the forces needed to create a van der Waals interface between the 2D material and the insulator.

Making the matrix

To make electronic devices, they form a hybrid surface of metals and insulators on a carrier substrate. This surface is then peeled off and flipped over to reveal a completely smooth top surface that contains the building blocks of the desired device.

This smoothness is important, since gaps between the surface and 2D material can hamper van der Waals interactions. Then, the researchers prepare the 2D material separately, in a completely clean environment, and bring it into direct contact with the prepared device stack.

“Once the hybrid surface is brought into contact with the 2D layer, without needing any high-temperatures, solvents, or sacrificial layers, it can pick up the 2D layer and integrate it with the surface. This way, we are allowing a van der Waals integration that would be traditionally forbidden, but now is possible and allows formation of fully functioning devices in a single step,” Satterthwaite explains.

This single-step process keeps the 2D material interface completely clean, which enables the material to reach its fundamental limits of performance without being held back by defects or contamination.

And because the surfaces also remain pristine, researchers can engineer the surface of the 2D material to form features or connections to other components. For example, they used this technique to create p-type transistors, which are generally challenging to make with 2D materials. Their transistors have improved on previous studies, and can provide a platform toward studying and achieving the performance needed for practical electronics.

Their approach can be done at scale to make larger arrays of devices. The adhesive matrix technique can also be used with a range of materials, and even with other forces to enhance the versatility of this platform. For instance, the researchers integrated graphene onto a device, forming the desired van der Waals interfaces using a matrix made with a polymer. In this case, adhesion relies on chemical interactions rather than van der Waals forces alone.

In the future, the researchers want to build on this platform to enable integration of a diverse library of 2D materials to study their intrinsic properties without the influence of processing damage, and develop new device platforms that leverage these superior functionalities.  

This research is funded, in part, by the U.S. National Science Foundation, the U.S. Department of Energy, the BUnano Cross-Disciplinary Fellowship at Boston University, and the U.S. Army Research Office. The fabrication and characterization procedures were carried out, largely, in the MIT.nano shared facilities.

Judy Hoyt, a pioneer in semiconductor research and retired MIT professor of electrical engineering and computer science, passed away on Aug. 6. She was 65.

Hoyt is known well for her groundbreaking research on strained silicon semiconductor materials, work which helped greatly decrease the size of integrated circuits. Her most recognized contribution was the first demonstration of the incorporation of lattice strain as a means to enhance performance in scaled silicon devices, a key concept behind the continuation of Moore’s Law roadmap for the last 20 years. This contribution has informed virtually every high-performance chip manufactured today, leading directly to the growth of both the $500 billion semiconductor industry and the multi-trillion-dollar electronics market. 

Hoyt’s contributions earned her the 2011 IEEE Andrew S. Grove Award (together with Eugene Fitzgerald) and the 2018 University Research Award by the Semiconductor Industry Association in collaboration with the Semiconductor Research Corporation. 

Hoyt was a native of Garden City in Long Island, New York. She was not only a talented musician, simultaneously leading her high school band and a swing jazz band, but also a dedicated student, who earned the rank of valedictorian before going on to earn her undergraduate degree in physics and applied mathematics at the University of California at Berkeley in 1980, and her MS and PhD degrees in applied physics at Stanford University in 1983 and 1987, respectively.

After graduation, she stayed on at Stanford as research associate and then senior research associate before joining the faculty of the MIT Department of Electrical Engineering and Computer Science as professor in 2000. From 2005 to 2018, she served as an associate director within the Microsystems Technology Laboratories (MTL) at MIT. She was also an effective proponent and key contributor to the configuration and design of the new MIT.nano building.

Throughout her academic career, Hoyt was a dedicated teacher and mentor to her students at both Stanford and MIT, many of whom went on to distinguished careers in the semiconductor industry. 

Outside of MIT, she was an avid cyclist who loved the outdoors, and animals; her lifelong love of music sustained her as well. 

All at MIT who knew Hoyt will remember her as a gentle soul and a caring friend whose puckish humor and unassuming demeanor hid a stern wisdom, unimpeachable sense of responsibility, and passionate loyalty to her students and her family.

She is survived by sister Barbara, brothers Robert and John, and her father George, as well as longtime close friends and colleagues Conor Rafferty and Dimitri Antoniadis.

Contributions in Hoyt’s memory can be made to St. Jude’s Hospital or the Jimmy Fund in Boston.

MIT researchers and colleagues have demonstrated a way to precisely control the size, composition, and other properties of nanoparticles key to the reactions involved in a variety of clean energy and environmental technologies. They did so by leveraging ion irradiation, a technique in which beams of charged particles bombard a material.

They went on to show that nanoparticles created this way have superior performance over their conventionally made counterparts.

“The materials we have worked on could advance several technologies, from fuel cells to generate CO₂-free electricity to the production of clean hydrogen feedstocks for the chemical industry [through electrolysis cells],” says Bilge Yildiz, leader of the work and a professor in MIT’s departments of Nuclear Science and Engineering and Materials Science and Engineering.

Critical catalyst

Fuel and electrolysis cells both involve electrochemical reactions through three principal parts: two electrodes (a cathode and anode) separated by an electrolyte. The difference between the two cells is that the reactions involved run in reverse.

The electrodes are coated with catalysts, or materials that make the reactions involved go faster. But a critical catalyst made of metal-oxide materials has been limited by challenges including low durability. “The metal catalyst particles coarsen at high temperatures, and you lose surface area and activity as a result,” says Yildiz, who is also affiliated with the Materials Research Laboratory and is an author of an open-access paper on the work published in the journal Energy & Environmental Science.

Enter metal exsolution, which involves precipitating metal nanoparticles out of a host oxide onto the surface of the electrode. The particles embed themselves into the electrode, “and that anchoring makes them more stable,” says Yildiz. As a result, exsolution has “led to remarkable progress in clean energy conversion and energy-efficient computing devices,” the researchers write in their paper.

However, controlling the precise properties of the resulting nanoparticles has been difficult. “We know that exsolution can give us stable and active nanoparticles, but the challenging part is really to control it. The novelty of this work is that we’ve found a tool — ion irradiation — that can give us that control,” says Jiayue Wang PhD ’22, first author of the paper. Wang, who conducted the work while earning his PhD in the MIT Department of Nuclear Science and Engineering, is now a postdoc at Stanford University.

Sossina Haile ’86, PhD ’92, the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University, who was not involved in the current work, says:

“Metallic nanoparticles serve as catalysts in a whole host of reactions, including the important reaction of splitting water to generate hydrogen for energy storage. In this work, Yildiz and colleagues have created an ingenious method for controlling the way that nanoparticles form.”

Haile continues, “the community has shown that exsolution results in structurally stable nanoparticles, but the process is not easy to control, so one doesn’t necessarily get the optimal number and size of particles. Using ion irradiation, this group was able to precisely control the features of the nanoparticles, resulting in excellent catalytic activity for water splitting.”

What they did

The researchers found that aiming a beam of ions at the electrode while simultaneously exsolving metal nanoparticles onto the electrode’s surface allowed them to control several properties of the resulting nanoparticles.

“Through ion-matter interactions, we have successfully engineered the size, composition, density, and location of the exsolved nanoparticles,” the team writes in Energy & Environmental Science.

For example, they could make the particles much smaller — down to 2 billionths of a meter in diameter — than those made using conventional thermal exsolution methods alone. Further, they were able to change the composition of the nanoparticles by irradiating with specific elements. They demonstrated this with a beam of nickel ions that implanted nickel into the exsolved metal nanoparticle. As a result, they demonstrated a direct and convenient way to engineer the composition of exsolved nanoparticles.

“We want to have multi-element nanoparticles, or alloys, because they usually have higher catalytic activity,” Yildiz says. “With our approach, the exsolution target does not have to be dependent on the substrate oxide itself.” Irradiation opens the door to many more compositions. “We can pretty much choose any oxide and any ion that we can irradiate with and exsolve that,” says Yildiz.

The team also found that ion irradiation forms defects in the electrode itself. And these defects provide additional nucleation sites, or places for the exsolved nanoparticles to grow from, increasing the density of the resulting nanoparticles.

Irradiation could also allow extreme spatial control over the nanoparticles. “Because you can focus the ion beam, you can imagine that you could ‘write’ with it to form specific nanostructures,” says Wang. “We did a preliminary demonstration [of that], but we believe it has potential to realize well-controlled micro- and nano-structures.”

The team also showed that the nanoparticles they created with ion irradiation had superior catalytic activity over those created by conventional thermal exsolution alone.

Additional MIT authors of the paper are Kevin B. Woller, a principal research scientist at the Plasma Science and Fusion Center (PSFC), home to the equipment used for ion irradiation; Abinash Kumar PhD ’22, who received his PhD from the Department of Materials Science and Engineering (DMSE) and is now at Oak Ridge National Laboratory; and James M. LeBeau, an associate professor in DMSE. Other authors are Zhan Zhang and Hua Zhou of Argonne National Laboratory, and Iradwikanari Waluyo and Adrian Hunt of Brookhaven National Laboratory.

This work was funded by the OxEon Corp. and MIT’s PSFC. The research also used resources supported by the U.S. Department of Energy Office of Science, MIT’s Materials Research Laboratory, and MIT.nano. The work was performed, in part, at Harvard University through a network funded by the National Science Foundation.

Metamaterials are products of engineering wizardry. They are made from everyday polymers, ceramics, and metals. And when constructed precisely at the microscale, in intricate architectures, these ordinary materials can take on extraordinary properties.

With the help of computer simulations, engineers can play with any combination of microstructures to see how certain materials can transform, for instance, into sound-focusing acoustic lenses or lightweight, bulletproof films.

But simulations can only take a design so far. To know for sure whether a metamaterial will stand up to expectation, physically testing them is a must. But there’s been no reliable way to push and pull on metamaterials at the microscale, and to know how they will respond, without contacting and physically damaging the structures in the process.

Now, a new laser-based technique offers a safe and fast solution that could speed up the discovery of promising metamaterials for real-world applications.

The technique, developed by MIT engineers, probes metamaterials with a system of two lasers — one to quickly zap a structure and the other to measure the ways in which it vibrates in response, much like striking a bell with a mallet and recording its reverb. In contrast to a mallet, the lasers make no physical contact. Yet they can produce vibrations throughout a metamaterial’s tiny beams and struts, as if the structure were being physically struck, stretched, or sheared.

The engineers can then use the resulting vibrations to calculate various dynamic properties of the material, such as how it would respond to impacts and how it would absorb or scatter sound. With an ultrafast laser pulse, they can excite and measure hundreds of miniature structures within minutes. The new technique offers a safe, reliable, and high-throughput way to dynamically characterize microscale metamaterials, for the first time.

“We need to find quicker ways of testing, optimizing, and tweaking these materials,” says Carlos Portela, the Brit and Alex d’Arbeloff Career Development Professor in Mechanical Engineering at MIT. “With this approach, we can accelerate the discovery of optimal materials, depending on the properties you want.”

Portela and his colleagues detail their new system, which they’ve named LIRAS (for laser-induced resonant acoustic spectroscopy) in a paper appearing today in Nature. His MIT co-authors include first author Yun Kai, Somayajulu Dhulipala, Rachel Sun, Jet Lem, and Thomas Pezeril, along with Washington DeLima at the U.S. Department of Energy’s Kansas City National Security Campus.

A slow tip

The metamaterials that Portela works with are made from common polymers that he 3D-prints into tiny, scaffold-like towers made from microscopic struts and beams. Each tower is patterned by repeating and layering a single geometric unit, such as an eight-pointed configuration of connecting beams. When stacked end to end, the tower arrangement can give the whole polymer properties that it would not otherwise have.

But engineers are severely limited in their options for physically testing and validating these metamaterial properties. Nanoindentation is the typical way in which such microstructures are probed, though in a very deliberate and controlled fashion. The method employs a micrometer-scale tip to slowly push down on a structure while measuring the tiny displacement and forces on the structure as it’s compressed.

“But this technique can only go so fast, while also damaging the structure,” Portela notes. “We wanted to find a way to measure how these structures would behave dynamically, for instance in the initial response to a strong impact, but in a way that would not destroy them.”

A (meta)material world

The team turned to laser ultrasonics — a nondestructive method that uses a short laser pulse tuned to ultrasound frequencies, to excite very thin materials such as gold films without physically touching them. The ultrasound waves created by the laser excitation are within a range that can cause a thin film to vibrate at a frequency that scientists can then use to determine the film’s exact thickness down to nanometer precision. The technique can also be used to determine whether a thin film holds any defects.

Portela and his colleagues realized that ultrasonic lasers might also safely induce their 3D metamaterial towers to vibrate; the height of the towers — ranging from 50 to 200 micrometers tall, or up to roughly twice the diameter of a human hair — is on a similar microscopic scale to thin films.

To test this idea, Yun Kai, who joined Portela’s group with expertise in laser optics, built a tabletop setup comprising two ultrasonic lasers — a “pulse” laser to excite metamaterial samples and a “probe” laser to measure the resulting vibrations.

On a single chip no bigger than a fingernail, the team then printed hundreds of microscopic towers, each with a specific height and architecture. They placed this miniature city of metamaterials in the two-laser setup, then excited the towers with repeated ultrashort pulses. The second laser measured the vibrations from each individual tower. The team then gathered the data, and looked for patterns in the vibrations.

“We excite all these structures with a laser, which is like hitting them with a hammer. And then we capture all the wiggles from hundreds of towers, and they all wobble in slightly different ways,” Portela says. “Then we can analyze these wiggles and extract the dynamic properties of each structure, such as their stiffness in response to impact, and how fast ultrasound travels through them.”

The team used the same technique to scan towers for defects. They printed several defect-free towers and then printed the same architectures, but with varying degrees of defects, such as missing struts and beams, each smaller than the size of a red blood cell.

“Since each tower has a vibrational signature, we saw that the more defects we put into that same structure, the more this signature shifted,” Portela explains. “You could imagine scanning an assembly line of structures. If you detect one with a slightly different signature, you know it’s not perfect.”

He says scientists can easily recreate the laser setup in their own labs. Then, Portela predicts the discovery of practical, real-world metamaterials will take off. For his part, Portela is keen to fabricate and test metamaterials that focus ultrasound waves, for instance to boost the sensitivity of ultrasound probes. He’s also exploring impact-resistant metamaterials, for instance to line the inside of bike helmets.

“We know how important it is to make materials to mitigate shock and impacts,” Kai offers. “Now with our study, for the first time we can characterize the dynamic behavior of metamaterials and explore them to the extreme.”

This research was conducted, in part, using facilities at MIT.nano, and supported, in part, by the Department of Energy’s Kansas City National Security Campus, the National Science Foundation, and DEVCOM ARL Army Research Office through the MIT Institute of Soldier Nanotechnologies.