MIT researchers tackle the economic realities of fusion power

In the last decade, scientists have shown that fusion energy can work, as a physical process. Next question: Can it work economically? 

A study co-authored by MIT professors Dennis Whyte and Andrew W. Lo proposes a framework for understanding what’s needed to make fusion energy commercially viable in the marketplace. The method considers the physical inputs needed to sustain controlled fusion energy production, as well as the cost of building power plants that can compete in energy markets.

“It’s all the things that come along with finding, allocating, and spending money at this scale,” says Whyte, a professor of nuclear science and engineering at MIT and a key driver of the field’s progress, who co-authored the paper. “This is critical to what we do. We should look at the economics. If we want this technology to actually be meaningful in the world economy, we have to start getting straight with ourselves about these topics.” 

The goal of the paper, Whyte says, is to create “this framework, where are all the economics are clear, and then we understand what it would mean” for any fusion energy power plant. 

Fusion energy harnesses the reaction that powers the stars: the fusion of light nuclei. It is often referred to as “plasma fusion,” as the fusion reactions generate fuel in a plasma state, often confined by magnets or initiated by powerful lasers. Whyte says the goal is to generate abundant energy while also offering society attractive safety, licensing, and siting options.

In 2022, researchers at the National Ignition Facility in Livermore, California, one of the U.S. national labs, achieved a reaction with positive energy gain. Venture funding has also poured into the field in recent years, although there are still many challenges regarding the construction of viable commercial fusion energy.

“It’s challenging to reduce complex scientific and engineering requirements to economic consequences,” Lo says. “But if we don’t do that, we’re not going to get the funding we need to achieve the impact we want.”

The open-access publication, “Criteria for the economic viability of fusion power plants,” appears online in the Journal of Fusion Energy. The authors are Whyte, who is the Hitachi America Professor of Engineering and a professor of nuclear science and engineering at MIT; Lo, who is the Charles E. and Susan T. Harris Professor and a professor of finance at the MIT Sloan School of Management; Rachel Bielajew, an analyst with Rutherford Energy Ventures and a researcher at MIT’s Plasma Science and Fusion Center; Maria Hancock and Riley Moeykens of Rutherford Energy Ventures; and Guinevere Shaw of Rutherford Energy Ventures and MIT’s Plasma Science and Fusion Center.

Whyte is a former head of MIT’s Department of Nuclear Science and Engineering and a former director of MIT’s Plasma Science and Fusion Center. He co-founded Commonwealth Fusion Systems, an MIT spinoff firm that is one of the leaders in the fusion industry. Whyte and Lo also co-founded Rutherford Energy Ventures, a consultancy and investment advisory firm, which is working with the U.S. Department of Energy’s Oak Ridge National Laboratory to build a consortium for new fusion research. 

10 parameters, any power plant

The framework Whyte and Lo propose in the paper has 10 parameters for evaluating the economic viability of a fusion energy power plant. Some of these are scientific and physical, dealing with the energy consumed and produced in a given plant. Most of the parameters are in the realm of engineering and economics, such as the costs of plant construction.

A key inspiration for the framework is the so-called Lawson Criterion, derived in the 1950s, which describes the combinations of temperature, plasma density, and energy confinement time that can produce net energy from the plasma due to fusion, regardless of its absolute power or volume. Specifically it calculates a “plasma Q,” which is the ratio of fusion power produced to the external power required to sustain the plasma.

“The Lawson Criterion describes the scientific success of energy gain from fusion plasmas, while our framework generally describes economic Q, which is the ratio of capital gained to that expended,” Whyte explains.

The parameters in the framework describe engineering features of the fusion power plant such as power density, the efficiency of converting fusion power into an economic product, and the durability of components used in the energy conversion, in addition to costing and market parameters that assess the expenses and returns from invested capital. Or, as Whyte puts it, the framework is centered on what it takes to achieve a net-positive economic return, “but applied to practical power plant design.” In parallel to plasma Q, the economic Q described in the framework must be greater than 1 for basic viability.

Researchers have tried a variety of methods for generating and containing fusion energy. The paper’s framework, Whyte emphasizes, is “completely agnostic to whatever fusion concept you use, because the physical reality of fusion is that you expend money to build the capability to produce fusion power.” And the parameters do not depend on the size of any reactor being built; the framework is set up so that any inputs can be scaled to a given project or power output. 

“It doesn’t matter whether the fusion power plant is a small or large, the bottom line is: In both cases you better have money coming out that exceeds the money going in, otherwise it’s not going to be around for very long,” Lo says. 

One source of motivation for the paper, Whyte and Lo say, is to underscore the importance of accounting for all costs in fusion research as rigorously as possible. While researchers will be highly aware of the costs of basic experiments, estimating the costs of a fusion reactor is a somewhat different matter, but something leaders in the field have to be increasingly oriented around.

Fixing a missing link

That is certainly the case, the authors note, as new rounds of funding enter the fusion energy industry. Just last week, Commonwealth Fusion Systems obtained a new billion-dollar round of funding support from investors; it hopes to open its first working power plant in the 2030s, in the state of Virginia. 

Lo acknowledges that there will be uncertainties and challenging decisions involved in the development of the very first commercial fusion reactor. If successful, though, the industry might follow the path of learning by doing that has been common in energy and other industries, helping plants become more economical over time. 

“This pattern of learning by doing exists in all deep technology sectors,” says Lo, noting that sequencing a human genome is a million times cheaper right now than it was about 25 years ago. “We’re going to see the same thing, but maybe not to the same degree, in fusion energy.”

Lo has long worked to develop ways for scientific research to gain financial support in biotechnology — and is launching a new MIT Sloan educational program, called CATAPULT, to provide more tools for people in any field of study to translate their research advances into products. 

When it comes to fusion, Lo says, “It’s pretty clear that economic viability is something we can start assessing now.” And while there might be thousands of particular decisions involved in building a commercial fusion plant, the authors think they have an overall approach that will let people quantify all that work. 

“When you’ve got a framework to evaluate it in a quantitative way, it tells you about the literal worth of making a particular design decision. That seems to me at this moment of fusion development absolutely critical, and what we’ve been missing,” Whyte says.

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Physicists watch a material’s electrons assemble, and reassemble, into coexisting phases

A tall glass of ice water isn’t just a thirst quencher; it’s also an everyday example of coexisting phases. Water’s molecular makeup can exist simultaneously in both a liquid and solid phase. And as it turns out, this phase duality can exist in more exotic, quantum materials, and in ways that are far more complicated to tease apart. 

A new study by MIT physicists sheds light on how two different phases of electron behavior can emerge and coexist in the same quantum material. 

Their results, reported today in the journal Nature Physics, can help to explain how some materials host superconductivity, magnetism, and other electronic phases. Untangling such phases, and understanding how they emerge, will help engineers control electronic behavior and design high-performance quantum devices. 

“People believe the cornerstone of replacing silicon lies in quantum materials that have multiple coexisting phases,” says co-author Alfred Zong PhD ’20, who co-led the study as an MIT graduate student and is now an assistant professor at Stanford University. “Our experiment provides a very neat way to study these multiple phases.”

The team, led by Nuh Gedik, the Donner Professor of Physics at MIT, studied the rare-earth material erbium tritelluride. As with most materials, erbium tritelluride’s electrons are normally scattered uniformly throughout the material. But when cooled to certain temperatures, the electrons suddenly organize into a wave-like pattern, which physicists term a “charge density wave” (CDW) phase. When cooled even further, electrons coordinate again as a second wavy phase that criss-crosses the first. The effect is of an atomic checkerboard of co-existing electron phases. 

Now, Gedik and his colleagues have teased apart erbium tritelluride’s phases and observed how each phase emerges. They found that one phase forms gradually, similar to how liquid water transitions uniformly into vapor. This is the classic, textbook way in which electronic phase transitions are thought to occur.

But the second phase came about in an entirely new and unexpected way: Instead of emerging gradually, the electrons organized first in pockets that eventually expanded, similar to how liquid water crystallizes into ice. 

“The mechanism responsible for the emergence of this second phase has long been debated, and our approach provides a powerful new way to uncover the hidden physics behind phase transitions in quantum materials,” Gedik says.

The study’s other MIT co-authors are first authors Yifan Su PhD ’24 and Bai-Qing Lv, a former postdoc; Dongsung Choi SM ’17, PhD ’24; and former postdocs Doron Azoury and Masataka Mogi; along with collaborators from multiple other institutions.

A clear view

A charge density wave is made up of charges, such as electrons, that spontaneously organize as a wave. The wave’s crests hold the highest density of electrons, and the lowest are found in the troughs. In some materials, electrons transition into this strange coordinated phase at super-cold temperatures. 

Scientists have observed charge density waves for decades, and most recently in materials that also host other, more complicated forms of electron coordination, such as various forms of magnetism, and superconductivity, in which electrons pair up and flow through a material without friction. 

“Just like superconductivty, charge density waves are a collective phenomena where electrons move together in certain ways,” explains lead author Yifan Su. “The power of CDWs is that they are a much simpler form of matter compared to superconductivity. They offer a playground for fundamental understanding.”

Su and the team looked to get a clear view of charge density waves in a material that hosts two CDW phases simultaneously. How these waves emerge and coexist in a single material could shed light on how superconductivity and other more complicated phase transitions occur. 

“One of the biggest questions in physics is why some materials host multiple phases while others do not. And when multiple phases do exist, how do they interact? Do they reinforce one another, compete, or coexist independently?” Gedik says. “This is like a case study for us to understand much more complicated materials.”

Shake, then listen

Scientists have observed two different charge density waves in erbium tritelluride — a rare-earth material that can be synthesized in the lab, in atomically thin sheets that can then be probed for unique, quantum-scale properties. 

In previous experiments, physicists have found that when erbium tritelluride is cooled down to -8 degrees Celsius, the first of two charge density waves forms among the material’s electrons. This “dominant” wave stretches across the material in one direction. When the material is further cooled to -113 degrees Celsius, a second, “subdominant” charge density wave emerges, perpendicular to the first, creating a checkerboard of coexisting electronic phases. 

In their new study, Gedik and his colleagues sought to tease out how each phase emerges in erbium tritelluride. The team obtained small, atomically thin samples of the material, which were synthesized by collaborators at Stanford. In Gedik’s lab, the researchers then cooled the samples down to about -230 degrees Celsius — temperatures at which the material should host both charge density waves, in a simultaneous, checkerboard pattern. They then either destroyed or weakened the checkerboard, and watched how both types of waves reemerged. 

To do so, they exposed each cooled sample to a one-two punch of laser pulses. 

“This is how we ‘shake’ and then ‘listen’ to the system,” Gedik says.

The first pulse was the “shake” that dissolved the checkerboard. The researchers could control the intensity of this kick to vary the degree to which the waves were disturbed. They then delivered a second laser pulse, of high-energy photons, to kick out electrons from the material. This second pulse was sent in at various times after the first pulse. The researchers then measured the energy and momentum of the kicked-out electrons, to get snapshots of how the material’s electronic phases recovered. 

“We see the destroying of these phases, and then if we wait long enough, they come back,” Gedik explains. “And depending on how you hit them, the two phases respond differently.”

From their experiments, the team found that the first, dominant phase of charge density waves reemerges gradually and uniformly, no matter how hard the material was initially “kicked.” This smooth restoration is a textbook, “second-order” phase transition, similar to a magnet gradually losing its magnetism as it is heated.

What was more surprising was how the second wave pattern reemerged. This subdominant phase reformed more like water into ice. The electrons reassembled the wave in isolated pockets that spread, like crystals of ice. This more rare, “first-order” transition was not expected. The team’s study captured the the long-debated mechanism underlying the emergence of the subdominant CDW phase. 

“In systems that are much more complex, like high-temperature superconductors, you see there are multiple phases — magnetism, superconductivity, charge density waves, and they all exist together,” Gedik says. “One of the theories is that, the way they interact with each other is key for their exotic properties. The lessons we learn here can be applied to much more complex materials.”

This work was supported by the U.S. Department of Energy, the U.S. National Science Foundation, and the Gordon and Betty Moore Foundation’s EPiQS Initiative grant.

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Akirah Bradley-Armstrong named vice chancellor for student life

MIT has appointed Akirah Bradley-Armstrong as vice chancellor for student life, effective Oct. 19, 2026. 

The appointment, following a national search, was announced yesterday in a letter sent to the MIT community from Chancellor Melissa Nobles, to whom Bradley-Armstrong will report. Bradley-Armstrong will succeed Vice Chancellor for Student Life Suzy M. Nelson, who transformed student life at MIT during her 10 years in the role. Nelson announced her retirement earlier this year.

Bradley-Armstrong joins MIT from the University of California at Santa Cruz, where she has served as vice chancellor for student affairs and success since 2022. In that role, she has led one of the university's largest divisions, overseeing approximately 800 professional staff, 2,100 student employees, and more than 30 departments dedicated to supporting student success, health and wellness, housing, athletics, recreation, and campus life. She has served as a principal advisor to UCSC’s chancellor on student issues and collaborated with the academic deans, faculty, and the campus provost on student initiatives. 

“Akirah is an accomplished and compassionate leader whose commitment to student success, belonging, and well-being has been demonstrated throughout her career,” says Nobles. “She brings a deep understanding of the challenges students face today, extensive expertise leading complex organizations, and a collaborative approach that will help her continue the work we have done to strengthen the student experience at MIT.”

The Office of the Chancellor oversees student life and learning at MIT. In her new role, Bradley-Armstrong will lead the student life side of that mission for undergraduate and graduate students. This broad portfolio encompasses dining; well-being and support; student organizations and events; the Department of Athletics, Physical Education and Recreation; and living communities, including oversight of the faculty-led residential house system. 

Before assuming her current role at UC Santa Cruz, Bradley-Armstrong was the vice chancellor for student affairs at the University of Colorado at Boulder and held senior student life roles at the University of California at Berkeley. Bradley-Armstrong is a nationally recognized leader in higher education who served on the board of the National Association of Student Personnel Administrators and chaired its 2025 national conference.

“Throughout my career, I have partnered with high-achieving students across multiple institutions and understand that extraordinary achievement must be paired with strong investments in well-being, mental health, and belonging,” says Bradley-Armstrong. “I’m particularly energized by MIT’s large graduate student population, having worked with graduate students on housing, childcare, and student support, while also teaching a graduate course at CU Boulder. I’m equally drawn to MIT's residential house system, which clearly plays a critical role in the lives of students.”

Bradley-Armstrong has extensive experience leading institutions through periods of change and responding to complex student issues. She has collaborated with campus partners to develop policies and programs that promote dynamic campus communities. Grounded in her background as a first-generation college graduate, student-athlete, and sorority member, Bradley-Armstrong has earned a reputation for leading with deep integrity and an unshakeable commitment to student success. 

“I am honored to join MIT and to serve alongside its students, faculty, and staff to support an exceptional student experience,” Bradley-Armstrong says. “MIT has a remarkable tradition of innovation, excellence, and community. I look forward to listening, learning, and building on the Institute's strong commitment to helping every student thrive.”

Nobles notes, “Throughout her career, Akirah has driven high-impact, system-level change across residential and Greek life, dining, athletics, and campus planning. Her innovative approach led to the launch of the University of California system’s first campus mobile crisis response team, the establishment of a two-year housing guarantee, and the advancement of initiatives of the UC Santa Cruz strategic plan.”

Bradley-Armstrong earned a Doctor of Education in Educational Leadership from the University of California at Davis. Her doctoral research examined how universities respond to tragedy as well as the support systems that help administrators navigate crisis response and recovery. She also holds a Master of Education in Higher Education and Student Affairs Administration from the University of Vermont, and a bachelor's degree from Mansfield University. 

“I look forward to welcoming Akirah to MIT and to working alongside her — and our whole community — to shape MIT’s next chapter of student life,” says Nobles.

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A new way to watch heat move through electronics

The same overheating problem that happens to our laptops also plagues computer servers and data centers around the world — and heat management is only getting harder as computer chips get more compact and powerful.

Understanding how heat moves through chips at the micro scale is essential for continuing to improve their performance. Unfortunately, most methods for measuring heat flow struggle with multilayered devices like the electronics that power our modern world.

Now MIT researchers have demonstrated a new way to study how heat moves through multilayered materials, combining X-rays that penetrate multiple layers with laser pulses for delivering heat. The researchers used the technique to measure how heat moves inside a promising device for transistors and flexible electronics. 

The method was so precise it allowed the researchers to quantify the effect of a single micron-scale defect in the device, revealing a surprising fourfold reduction in the material’s ability to transfer heat at that spot. They also found that the defect caused heat to spread unevenly, moving more easily in one direction than in the other.

The team believes the approach could help researchers understand overheating in devices and help companies develop more power-dense electronics for everything from AI applications to wearables and clean energy systems.

“Chip developers need devices that can handle heat,” says Mingda Li, an associate professor of nuclear science and engineering at MIT and co-corresponding author on an open-access paper about the work in Nature Communications. “I think overheating has become the real bottleneck in device performance. When doing these diagnoses using traditional techniques, they couldn’t get down to the micro- or nanometer scale. But eventually they’d like to go beyond that to study the heat carriers and understand exactly what causes failure, in order to avoid local hotspots and design better devices. This approach is a step in that direction.”

Joining Li on the paper are co-lead authors Thanh Nguyen PhD ’24 and MIT postdoc Chuliang Fu; PhD candidate Mouyang Cheng; Abhijatmedhi Chotrattanapituk ’21, SM ’26; Denisse Córdova Carrizales SM ’26; Eunbi Rha SM ’26; Tyra Espedal ’26; Buxuan Li PhD ’24; Shivam Kajale SM ’23, PhD ’26; Tongtong Liu PhD ’23; Kuan Qiao PhD ’22; University of Texas at Austin Assistant Professor Zhantao Chen SM ’18, PhD ’22; Argonne National Laboratory researchers Kumar Neeraj, Donald Walko, and Haidan Wen; MIT Principal Research Scientist Svetlana Boriskina; MIT Associate Professor Deblina Sarkar; and co-corresponding author and MIT Associate Professor Jeehwan Kim.

Tracking heat

Making more powerful computers and electronics often comes down to cramming more transistors into a smaller area. But the closer those transistors get to each other, the hotter the device gets as it operates, and the more heat needs to be moved.

Most people learn about the problem from their laptops overheating on their lap. At the data center scale, it means an enormous amount of energy must be devoted to cooling the servers.

The quest to design more power-dense computers and electronics is thus a quest to find materials that can transport heat most efficiently.

Researchers have used a number of methods to measure and model heat flow across materials, but they all have limitations when it comes to studying realistic device architectures. One common optical method to study heat at the microscopic level, for instance, is called time domain thermal reflectance.

“Because that technique uses optics, it doesn’t allow you to study different layers,” Kim explains. “Real devices have five or more layers. It also only provides an overall signal, and that makes it hard to see thermal transport happening in layers buried under the surface.”

Other techniques, like infrared cameras, don’t capture tiny changes at a fast enough frame rate to be useful at small scales.

To address those limitations, the researchers wanted to create something that could measure heat transfer at the nanoscale in multilayer systems. To do that, they used an emerging analysis technique that sends electron pulses and ultrafast X-rays at a material and measures changes in energy.

“Over the last few years, researchers have developed what is basically the brightest X-ray source in the world,” Nguyen says. “That allows you to focus an X-ray beam and get incredibly fine spatial resolution. You can also use a laser to heat the sample while the X-ray scans and shows how the heat dissipates across space in real-time.”

The technique offered a better view of heat transfer because the laser-powered electron pulse can capture changes in material strain at the atomic level while the X-rays can penetrate into multiple layers of the material, and the measurements can be combined to provide a clearer view of how a material moves heat.

“Using previous measurement techniques, in real devices, you couldn’t resolve what happens on one layer versus another, so you’d just measure the average,” Fu says. “X-rays can clearly show how heat propagates across the interface through their diffraction.”

The researchers applied their technique to a test device made of a layer of gallium nitride, which has shown promise for conducting heat efficiently, on top of silicon. The material combination has been studied for years, but its thermal performance has been shown to deteriorate because of tiny defects created during processing.

The researchers measured a fourfold reduction in heat dissipation across a wrinkle defect on the device and a 25 percent drop in heat dissipation across materials, showing more disruption to heat flow than they had expected.

“When people model heat dissipation, they model perfect crystals without defects,” Li says. “But these types of large wrinkle defects are very common in 2D materials. People never even knew how much heat is blocked by these wrinkles. Those are things we can now directly observe with this technique.”

Designing better chips

Li says a leading semiconductor industry consortium has already reached out to collaborate on applying the measurement technique to study different types of chips. He believes the technique will work to study a wide array of materials and devices.

“We can now pass a current and shine an X-ray on a device and see how the heat dissipates at a very small scale,” Kim says. “That’s something the industry has been longing for.”

Li says the approach will provide researchers with new information to improve the design of electronic systems.

“This will enable better thermal design of electronic systems,” Kim says. “Even with the same type of materials, the geometry and how the materials are laid out is quite complicated, so it will show us how those differences impact thermal flow by providing direct experimental measurements.”

The work was supported, in part, by the U.S. Department of Energy, the U.S. National Science Foundation, and the MIT School of Engineering Distinguished Energy Efficiency Fellowship.

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Researchers make air-stable, ultrathin superconductors, for more scalable quantum devices

Super-thin superconducting materials, which are only one or a few atoms thick, have unique properties scientists can leverage to produce more compact, scalable, and efficient quantum devices. But these fragile materials degrade so rapidly in air that they are difficult to study or manufacture.

Now, researchers from MIT and elsewhere have discovered and harnessed a method to generate a large, uniform area of ultrathin superconducting material that remains stable in air. 

They “grow” the superconducting material, called niobium diselenide, underneath another atomically thin material, carbon-based graphene. The graphene layer protects the fragile superconductor from oxidation, while guiding it to grow in a smooth layer over a large wafer-scale area.

The researchers further integrated this air-stable superconductor into a superconducting microwave circuit. When tested, the material maintained its superconducting properties and exhibited high kinetic inductance, which is a resource for many quantum devices. 

In the long run, this advance could help miniaturize superconducting quantum computing hardware, as well as technologies like ultrasensitive quantum detectors for communications or cosmology.

“Emerging superconductors that are only a monolayer thick have a lot of potential. Thanks to our new process, they are no longer materials that can only be made at a very small scale. There are now exciting opportunities for scientists to study these materials, utilize them in circuits, and explore their practical applications,” says co-lead author Xudong Sheldon Zheng, a graduate student in the MIT Department of Electrical Engineering and Computer Science (EECS).

He is joined on the paper by co-lead authors Sameia Zaman SM ’24, an EECS graduate student, and Kenan Zhang, a recent postdoc in the MIT Research Laboratory of Electronics (RLE); corresponding authors William D. Oliver, the Henry Ellis Warren (1894) Professor of EECS and professor of physics, director of the Center for Quantum Engineering, and associate director of RLE; Joel Î-j. Wang, an assistant professor at New York University; and Jing Kong, the Jerry Mcafee (1940) Professor in Engineering at MIT and a member of RLE; as well as others at MIT and Lincoln Laboratory, Rice University, Yale University, and Pohang University in South Korea. The research appears today in Nature.

Powerful properties

Superconductors are materials that can conduct electricity without resistance, and they are essential for some types of quantum devices. 

Two-dimensional superconducting materials retain their superconducting properties despite being only a few atoms thick. These materials hold the promise to miniaturize superconducting circuitry.

Niobium diselenide, an ultrathin superconductor composed of a single, closely packed layer of niobium atoms sandwiched between a single layer of selenium atoms on either side, has a very high kinetic inductance, as members of the research team recently reported.

This enables the material to store a great deal of inductive energy in a very small area. Large kinetic inductance in a small form-factor is a desirable design element in many quantum devices. 

One commonly used approach to realizing a large kinetic inductance is to string together an array of devices called Josephson junctions.

If scientists could incorporate materials such as thin niobium diselenide with sufficiently large kinetic inductance into a quantum circuit, they could replace the large area of electronic junctions with a tiny piece of thin-film material, making the circuit more compact. But because niobium diselenide degrades rapidly in air, scientists have not been able to reliably fabricate devices at the wafer scale. Instead, they rely on exfoliation techniques that yield small flakes. Furthermore, researchers have struggled to grow material with uniform monolayer thickness. Consequently, it has been challenging to fully probe its properties or test it in practical applications.

“Typically, once we make the material and remove it from its inert environment, it immediately starts to oxidize and degrade, ultimately becoming damaged,” Zheng explains.

Scientists usually grow niobium diselenide by depositing chemical precursors onto a silicon dioxide substrate. Then they place another layer of two-dimensional material, like graphene or hexagonal boron nitride, on top to protect the fragile superconductor from air.

But such postgrowth protection presents a challenge. The superconductor begins to oxidize almost immediately after synthesis, degrading its properties before it is protected. Meanwhile, the protection process requires a stringent inert environment and delicate processing.

Mind the gap

The MIT researchers used a different tactic. They put the layer of graphene on top of the silicon dioxide substrate first. Then they deposited the precursors and grew the superconducting material in the tiny gap between the two layers.

“It took a long time for us to understand how the growth could happen underneath the graphene. Through collaboration and discussion, we eventually uncovered the mechanism for growing the material at the interface, and this solves a lot of problems and allows us to simplify our fabrication steps,” Zheng says.

The silicon dioxide substrate helps trap the precursors long enough for the crystal to begin forming, while the graphene layer allows them to move around easily and spread into a continuous monolayer.

The researchers used this technique to generate a perfectly smooth layer of niobium diselenide more than an inch in size.

“By carefully tuning the growth conditions, we can ensure the material grows between the layers in exactly the way we’ve designed,” Zheng says.

Even though the graphene is placed on top of the silicon dioxide, the weak adhesion between these materials leaves a gap between them less than 1 nanometer thick. The niobium diselenide grows only within that gap. Then, since it is already encapsulated by graphene, the researchers can safely remove it into the ambient environment without causing degradation.

Careful connections

The researchers also designed an oxidation-free transfer technique to peel the graphene-niobium diselenide structure from its growth substrate, building on prior work by members of the team.

Then, they developed a method to integrate the thin film into a quantum circuit without hampering the fragile superconductor or its properties.

“It is challenging to make a good electrical connection between this very thin material, which is only about 1 nanometer in thickness, and our electrodes, which are a few hundred nanometers in thickness,” Zaman says.

They carefully etch the side walls of the thin-film superconductor in a vacuum chamber, which preserves the smooth edge of the material. When they integrate the prepared niobium-graphene structure into a conventional superconducting circuit, it forms a reliable electrical connection. Importantly, the material maintained its superconducting properties and exhibited high kinetic inductance after clean room fabrication and integration into the circuit. This makes it particularly attractive for fabricating compact superconducting quantum devices and other quantum technologies.

Furthermore, the growth strategy is not limited to monolayer niobium diselenide. The researchers demonstrated that it can be extended to a broad family of monolayer quantum materials with diverse and technologically important properties.

In the future, the researchers aim to integrate these ultrathin superconducting materials into functional device architectures to enable the exploration of fundamental physics and the prototyping of quantum devices and other advanced technologies.

“We’ve taken a very good step toward exploring both the physics and the application side of this thin, monolayer superconductor, which we can now grow in wafer scale or in even larger areas. There are a lot of directions we can go in the future,” Zaman says.

This research was funded, in part, by the U.S. Army Research Office, the U.S. National Science Foundation, the Schlumberger Foundation, the U.S. Department of Energy, the U.S. Air Force Office of Scientific Research, the Semiconductor Research Corporation Center, the MIT Institute for Soldier Nanotechnologies, and the National Research Foundation of Korea. This work was carried out, in part, using MIT.nano facilities.

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Scientists unveil more than 600 new tissue models of human cancer

To develop new targeted treatments for cancer, scientists need tissue models that accurately represent the genetic and molecular traits of the cancer they’re studying. An international team led by researchers at MIT’s Koch Institute, the Broad Institute, the Dana-Farber Cancer Institute, the National Cancer Institute, and numerous other partnering institutions has developed nearly 700 new cancer models, derived from patient tumors, which they hope will aid in drug development. 

These cells, which represent 25 different types of cancer, are now available for cancer researchers around the world to use. The project is described in a new paper appearing today in Nature, with contributors from more than two dozen institutions.

The models are the result of a 10-year initiative, funded by the National Cancer Institute, to expand the number of patient-derived tissue models available. For most of these models, the researchers converted tumor cells into organoids — 3D cell cultures that can survive indefinitely and mimic the genetic and molecular features of the tumors that they originally came from.

This type of model could help researchers identify new drug targets and test potential new treatments for many more types of cancer.

“Since the sequencing of the human genome and the analysis of cancer genomes over the last 20 years, we have had many ideas about cancer targets, but we need experimental systems in the lab to validate those targets and launch drug discovery projects,” says Jesse Boehm, a research scientist at the Koch Institute and one of the senior authors of the study.

From tumors to organoids

The Human Cancer Models Initiative was launched in 2016, following the completion of the Cancer Genome Atlas, an effort to catalog the genomic alterations responsible for cancer growth. 

For the atlas project, researchers sequenced cancer cell samples from thousands of patients. That work revealed that the diversity of tumor genetic profiles was not fully captured by the roughly 1,000 patient-derived cancer cell lines that existed at the time.

“We realized that a thousand wasn’t enough, that the international community needed to invest in many more thousands to represent all cancers, all genotypes, all ethnicities,” Boehm says. “Most existing models come from European and Southeast Asian patients, and many rare cancers are missing.”

Funded by the National Cancer Institute and the United Kingdom’s Wellcome Trust, hundreds of scientists across dozens of institutions participated in obtaining patient samples and developing them into cell lines that could be used for research.

“It’s been an enormous initiative, and this Nature paper is the culmination of that 10-year swath of activity,” Boehm says.

More than 2,700 tumor samples were obtained from hospitals participating in the study, from patients who gave their permission for their cells to be used for research. These samples were collected by hospitals in the United States, the United Kingdom, and the Netherlands. 

“A resource of this scale depends on the kind of systematic effort that often happens behind the scenes,” says Mushriq Al-Jazrawe, scientific director of the High Throughput Sciences (HTS) platform at the Koch Institute and one of the lead authors of the study. “I’m especially grateful to the technical and scientific teams across the participating institutes whose careful, expert work turns patient tumor samples into well-characterized models and data that researchers everywhere can use with confidence.”

Most of these samples came from commonly seen cancers such as lung, liver, and pancreatic, but they also included about 150 rare types including tumors of the gallbladder and the small intestine.

To convert these samples into cells that can survive indefinitely in the lab, the researchers developed techniques for culturing the cells in specialized growth media with a scaffold that helps them grow into a 3D structure. Overall, the researchers were able to successfully convert about one-third of the patient samples that they received.

Most of these new models consist of organoids, which in some cases more closely mimic the structure of the tissue that the cells came from. Traditional cancer cell lines, which were developed beginning in the 1950s, exist as single layers of cells grown in a lab dish, while organoids consist of three-dimensional balls of cells embedded in a gelatin-like structure.

Once the organoids and cell lines were established, which can take up to a year, the researchers analyzed them to make sure that their genomic sequences, RNA expression, and epigenomic modifications closely matched those of the tumor cells that they were derived from.

Cancer vulnerabilities

All of the models developed as part of the HCMI were deposited at the American Type Culture Collection (ATCC), a nonprofit distributor of cell lines. Each model also has extensive data from the patient whose cells were used to start the cell line, including mutations that the patient inherited from their parents (germline mutations), and information on the cancer treatments they received.

Using these models, scientists should be able to perform much larger scale screens that could aid in drug development efforts. 

In another paper also appearing in Nature today, Broad Institute researchers reported that they were able to profile more than 300 of the new models using high-throughput genome-sequencing, RNA sequencing, and more than 100 with CRISPR loss-of-function screens. This enabled them to identify vulnerabilities in each model that could be targeted with new drugs.

These findings have been added to a resource known as the Cancer Dependency Map (DepMap), which now includes information on more than 2,000 types of cancer.

In another Nature companion paper, researchers at the Sanger Institute led an effort to characterize an additional 256 organoids developed through the HCMI project. 

Additionally, even though most aspects of the formal HCMI project are currently winding down, researchers hope to continue developing models derived from additional patient tumor samples, including more pediatric cancers and rare cancers.

“We now have about 2,000, but if we really want to represent all humans with cancer in our preclinical research, more work is needed. We have to invite patients to donate tissue to make research tools that the whole world can use,” Boehm says. “I think this will hopefully be not the end, but the beginning.”

“A major opportunity now is to carry the lessons of HCMI forward, so we can generate as much insight as possible from these precious tissue donations,” says Al-Jazrawe, who is also a researcher in the Broad Institute’s Cancer Program. “Here at HTS, we are continuing the work by developing methods to study patient-derived samples and models reproducibly and at scale, and by providing a platform for close collaboration with clinical and research teams.”

Other senior authors of the HCMI paper are Mathew Garnett of the Wellcome Sanger Institute, David Tuveson of Cold Spring Harbor Laboratory, Andrea Califano of Columbia University Vagelos College of Physicians and Surgeons, Paul Spellman of the University of California at Los Angeles, Keith Ligon of Dana-Farber Cancer Institute, Daniela Gerhard of the NCI Center for Cancer Genomics, and Louis Staudt of the NCI Center for Cancer Research.

In addition to Al-Jazrawe, the paper’s lead authors are Dina El-Harouni of the Broad Institute and Dana Farber, Seongmin Choi of Memorial Sloan Kettering Cancer Center, Merve Dede of the University of Texas MD Anderson Cancer Center, Toshinori Hinoue of the Van Andel Institute, Sean Misek of the Broad Institute and Dana-Farber, Heeju Hoh of the Institute of Systems Biology and the Columbia University Vagelos College of Physicians and Surgeons, and Luca Zanella of the Columbia University Vagelos College of Physicians and Surgeons. 

The research was funded primarily by the National Cancer Institute and the Wellcome Trust.

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These 3D-printed objects can tell you if they’re being used properly

Imagine a bottle of hazardous chemicals sitting on a laboratory shelf that changes its appearance to alert scientists that its lid is not properly secured, potentially preventing a dangerous spill.

A new 3D-printing system created by MIT researchers enables users to produce interactive objects like this chemical bottle, which change their appearance when they are pressed, slid, or turned, without the use of any internal electronics. 

Their system simplifies the process of designing and fabricating 3D objects with mechanically switchable surface appearances, enabling individuals without technical expertise to quickly generate dynamic everyday objects.

The design and fabrication system combines specially arranged optical layers with built-in mechanical parts so a single object can display different images or patterns. The resulting objects change appearance based on user interactions like screwing on a lid or flipping a switch, and they can be manufactured in one pass on a multimaterial 3D printer.

The system can be used to fabricate a range of interactive objects that don’t require fragile electronic circuits, such as adaptable warning signs that could withstand foul weather or dynamic packaging that alerts users if fasteners came loose during shipping. 

The end-to-end system could also streamline rapid prototyping of adaptable objects for artistic, architectural, and engineering applications.

“With our system, an object can tell you whether you are using it properly, without the need for sensors or any complicated electronics. The interactive display is mechanical, so you can create a self-contained, multistate, interactive device that a user can control very intuitively,” says Yunyi Zhu, a graduate student in the MIT Department of Electrical Engineering and Computer Science (EECS) and lead author of a paper on this platform.

Her co-authors include Dingning Cao, an MIT undergraduate; Jeremy Mrzyglocki, a graduate student at the Technical University of Munich; Stefanie Mueller, an associate professor in EECS and the Department of Mechanical Engineering at MIT and a member of the Computer Science and Artificial Intelligence Laboratory (CSAIL); and Narjes Pourjafarian, a postdoc at Northeastern University. The research will be presented at the ACM Symposium on User Interface Software and Technology.

Mechanically switchable surfaces

Many interactive products rely on screens and electronics to change their appearance. But if these dynamic objects are exposed to water or harsh chemicals, or are squished, twisted, or pressed with great force, the fragile electronics could be damaged.

On the other hand, conventional methods that use surface optics to change an object’s appearance without electronics typically utilize static labels like stickers or curved lenses to create different visual effects based on where the user is looking, limiting interactivity.

To simplify the process of making dynamic, interactive objects that don’t require electronics, the MIT researchers developed a system that automatically converts a user’s design into a 3D printer-ready model of an object with a mechanically switchable surface appearance.   

Their design, ShiftLens, creates switchable appearances by combining two optical layers on an object’s surface. It places a layer of special lenses over an underlying, patterned backplane. 

The object displays different visual states based on the motion between the two layers. 

The lens layer contains an array of tiny lenticular lenses, curved lenses which steer light differently depending on the viewing angle of the user. The pattern layer contains strips of images that correspond to multiple appearances of the object surface.

When the user shifts the lens layer, different parts of the backplane come into view. The lenses magnify these parts of the backplane image, changing the surface appearance.

“The biggest challenge in this project was to make sure all moving parts align. We need to make sure that the optical effect, mechanical linkages, and computational graphics align with one another,” Zhu says.

A straightforward system

To simplify the design process, the researchers created a user-friendly tool that does all this work behind the scenes. 

It automatically generates a ShiftLens structure based on a few inputs, including images of the visual states the user wants to achieve and the desired shape and curves of the object.

“Another challenge is to communicate to users who are not familiar with optics or mechanical structures and let them specify and achieve what they have in mind,” she says.

The researchers thought carefully about how to communicate the limitations of the ShiftLens design tool to the user. For instance, ShiftLens is not compatible with all objects, since it requires a shifting motion to enable interaction between the two layers.

Users can either incorporate a ShiftLens into the design of an object that has this type of interaction built-in, like the rotation of a lipstick tube, or integrate an actuation mechanism like a switch, knob, or roller. 

“With ShiftLens, users can control what an object looks like while they are using it,” she says.

The researchers showcased how someone might use ShiftLens by fabricating a range of interactive objects.

In one experiment, they created a chemical bottle that turns green and displays a check mark when the cap is securely tightened, but turns red and displays an exclamation mark when it is loose. For another demonstration, they fabricated a tic-tac-toe game with squares that can display a red X, a blue O, or no letter, depending on which direction a user turns a knob.

While the ShiftLens tool is designed to simplify the fabrication process for makers, the techniques could be scaled up for commercial and industrial applications, Zhu says. For instance, it could be used to design piping that can change its appearance to identify a damaged connection that is causing a leak.

“The leaking sink in my apartment would be a lot easier to fix if it could tell me where the leak was coming from,” Zhu adds.

The researchers want to explore additional applications in future work. They also plan to develop an algorithm that can generate a ShiftLens structure with fewer user inputs, simplifying the design process. In addition, they plan to enhance the design tool so users can incorporate a wider variety of actuation mechanisms.

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