Seeing inside next-generation microelectronics using x-rays

As electronics shrink, researchers are turning to nanoscale materials like ultra-thin nanosheets for next-generation devices. Studying these tiny structures without damaging them is challenging, but scientists used a 12-nanometer-wide X-ray beam to examine them safely. This revealed two competing mechanisms behind how these nanosheets deform, offering insights crucial for advancing microelectronics.

Consumers want electronics that are ever smaller and faster. But the fabrication methods industry and researchers use to create tiny, high-power electronics are complex and can cause the nanostructures to have unwanted defects and deformations. Understanding these inner details—and doing so in a way that doesn’t cause further damage—is essential to determining how to use nanostructures in real-world applications. This study provides a non-destructive method for studying materials that yields insights into the structure of these devices at the nanoscale. It also opens a new avenue for developing novel nanoscale structures for electronics applications.

Nanosheets are used in tiny next-generation electronic components called Gate-All-Around Field Effect Transistors (GAAFETs). These components form the basis of computer microprocessors at the heart of smartphones and computers. In this study, a team of researchers from IBM collaborated with scientists from the National Synchrotron Light Source II (NSLS-II), a Department of Energy Office of Science user facility at Brookhaven National Laboratory, to map the deformations within nanosheets. The researchers investigated these structures using the Hard X-ray Nanoprobe (HXN) beamline at the NSLS-II light source.

By exploiting the brilliant source of X-rays and the resolving power provided by a nanofocusing optics setup called a multilayer Laue lens, the researchers were able to identify two competing mechanisms at different length scales that contribute to the deformation. The first, which is long-range and previously known, is due to the mismatch of lattice constant between the different elements and a relaxation effect near edges. The second, a much shorter-range effect, is associated with the layering itself and is dominant within a length scale of the nanosheet thickness from the edge. These new insights could help researchers predict essential performance parameters of future devices, such as the carrier mobility.

For more information: Nature Communications

Image: Artist’s impression of how X-rays make it possible to study the distortions of the layers in the microelectronics material. The atoms at the edges of the layers are either squished tighter or pulled apart, creating a bend along the different layers.

Testing and designing materials to perform better under stress

Nuclear fusion, the process powering the sun and stars, offers a promising path to carbon-free electricity without long-lasting nuclear waste, but it requires materials that can endure extreme heat, stress, and neutron damage. Researchers are exploring advanced metal alloys and ceramic composites as potential solutions to these challenges. At Stony Brook University, Assistant Professor David Sprouster is leading several research projects focused on overcoming the materials science and engineering hurdles critical to making fusion energy a practical reality.

“My research is really about stress testing these different materials to see how we can improve their function when exposed to different combinations of extremes,” said Sprouster. “It’s also fun to design them, to fabricate them in the lab, and then to break them.”

Sprouster and his team have received three multi-million dollar recent grants that focus on materials for fusion energy, with two from the Department of Energy, Office of Fusion Energy Sciences Fusion Innovation Research Engine (FIRE) Collaboratives.

In a recent study, Sprouster’s group compared two steels with similar alloy compositions, but fabricated in two different ways: one by traditional casting and the other through direct current sintering. In direct current sintering, both heat and pressure are used to rapidly convert powders into a solid monolithic material. As compared to conventional casting, this process allows the relatively complicated and graded structures of fusion chamber walls to be formed. Both fabricated steels are designed to resist deformation under heat and stress over time, a phenomenon known as “creep.”

“Creep is a very slow process — it happens over days, weeks, months and years — and depends on the applied stress and temperature,” said Sprouster. “It’s a tough moving target, but we have had success in designing the least ‘creepy’ materials, and to engineer the movement of dislocations, the defects within materials that allow plastic deformation to occur to improve our overall fundamental understanding of creep.”

Sprouster’s recent work concluded that both the conventionally cast and sintered materials showed equally good creep resistance. But they observed that when temperature increases, dislocations move more easily, which makes the material more prone to deformation. Equipped with this new knowledge, materials engineers can predict how these steels will perform under high-temperature service conditions, such as in fusion reactors.

In a second study, Sprouster’s group fabricated composites of steel with hafnium hydride through direct current sintering for neutron shielding applications within advanced nuclear fusion reactors. “The hydrogen is there to stop the neutrons. It has a very good cross-section for neutron absorption,” said Sprouster. “So, it basically takes most of the neutrons away so that you can shield the critical components that are close to the plasma.”

One of the key findings from this work was that upon heating, hafnium hydride breaks down and releases hydrogen, and the hafnium metal reacts with the iron to produce new intermetallic phases. However, due to the composite nature of this shield, the release is relatively show and at a much higher temperature than anticipated in the fusion reactor application.

These projects serve a shared purpose — to construct safer, more efficient and more durable materials for extreme nuclear environments for future fusion reactors.

“The fusion space has become an enormously attractive research area,” said Lance Snead, research professor in the Department of Materials Science and Chemical Engineering. “Historically, the Department of Energy was the primary agency funding this future energy source, but with the realization that fusion can be a near-term source of electricity, private investors now dominate the field.”

“Fusion is very exciting right now,” said Sprouster. “There’s a lot of activity and good collaborations across the universities, national labs and within industry. The community is very energetic and focused on materials science solutions to tough engineering problems.”

“Last year over 1.6 billion dollars in private research funding went into fusion, or three times that of the federal contribution,” said Snead. “As a key to the success of any of the current fusion concepts hinges on the ability to develop new and robust fusion chamber materials, Professor Sprouster has positioned his group in a very exciting growth area for research.”

Image: From left: Mingxi Ouyang, PhD student; Lance Snead, research professor; David Sprouster, assistant professor; and post-doctoral students Kent Christian and Jiao Li. Photos by John Griffin.

UC Irvine to lead use of AI in solving grand challenges below Earth’s surface

The University of California Office of the President has awarded $6 million over three years to a UC Irvine-led initiative called Geophysicist.AI, which aims to apply artificial intelligence to major geophysical challenges within Earth’s crust. The project focuses on advancing sustainable geothermal energy, underground carbon dioxide sequestration, and the safe, long-term storage of spent nuclear fuel, among other critical environmental goals.

“Tapping into Earth’s abundant but hard-to-reach deep geothermal energy and better understanding and potentially predicting induced seismicity, as well as other subsurface capabilities, will take new technologies and novel approaches, and we think AI and machine learning will help us in a substantial way,” said Geophysicist.AI lead principal investigator Mohammad Javad Abdolhosseini Qomi, UC Irvine associate professor of civil and environmental engineering and materials science and engineering.

“We intend to design Geophysicist.AI with the attributes of a skilled geophysicist, including the ability to integrate and analyze heterogeneous data and models, solve mathematical representations of coupled processes across scales, and formulate and test hypotheses to provide a deeper understanding and explanation of observed geophysical processes,” he added.

With UC Irvine researchers in the lead, the project will tap the expertise of civil and environmental engineers, geoscientists, mathematicians and computer scientists at UC campuses in Riverside, San Diego, Berkeley and Santa Cruz. Also participating will be scientists from Lawrence Livermore National Laboratory and Los Alamos National Laboratory.

“Our goal is to develop a scalable artificial intelligence ecosystem that integrates large language and physics-informed models with massive amounts of real-world data to transform geophysicists’ ability to solve the most difficult subsurface challenges,” said co-principal investigator Eric Mjolsness, UC Irvine professor of computer science. “Also, we believe that the development of Geophysicist.AI will require us to employ novel methods, so both the project and its outcome will be useful more broadly in scientific applications beyond geophysics.”

Russ Detwiler, UC Irvine associate professor of civil and environmental engineering, said that as co-principal investigator, he envisions the team using Geophysicist.AI to address two main grand challenges of geoengineering. The first is to help humanity tap into enhanced geothermal systems, which entails circulating fluid through low-permeability rock as much as 2.5 miles deep to extract heat and drive turbines. Detwiler said that this endeavor – aided by AI and machine learning – is complex due to the interplay of thermal, mechanical and chemical processes at multiple scales.

The second goal is to use AI and machine learning to help predict induced seismicity from engineering pursuits beneath Earth’s surface. The researchers think a problem of this intricacy is a good match for AI since it involves terabytes of seismic data being generated continuously.

A key source of data will be the Sanford Underground Research Facility in South Dakota. Geophysicist.AI scientists will join with counterparts at the Center for Understanding Subsurface Signals and Permeability, a U.S. Department of Energy Earthshot center managed through the Pacific Northwest National Laboratory, to gain access to this resource.

In addition, the team will take advantage of the Department of Energy’s multiphysics simulators, which run on DOE supercomputers. UC Irvine also has substantial high-performance computing capabilities and deep, interdisciplinary AI expertise that will benefit the project, Mjolsness said.

“Working with our principal investigators here at UC Irvine, scientists at the other UC campuses and collaborators at the national laboratories will enable us to generate sufficient preliminary proof-of-concept results, publish as a team and [promote] synergistic activities much like a full-blown research center,” Qomi said. “Our work over the next few years should put us in a good position to compete for future federal funding.”

For more information: University of California, Irvine
Image: Mohammad Javad Abdolhosseini Qomi (left), UC Irvine associate professor of civil and environmental engineering and materials science and engineering, is lead principal investigator on the Geophysicist.AI project, while colleagues Eric Mjolsness (center), professor of computer science, and Russ Detwiler (right), associate professor of civil and environmental engineering, are co-principal investigators.

Comet-catching NASA technology enables exotic works of art

Aerogel, composed of 99% air, is the lightest solid on Earth and has been used in diverse fields ranging from NASA missions to high fashion. Greek artist Ioannis Michaloudis, inspired by a dream to create a 3D cloud, spent over 25 years exploring aerogel as an artistic medium. His journey led him through institutions like MIT, Shivaji University in India, and NASA’s Jet Propulsion Laboratory. Introduced to aerogel by a researcher at MIT, Michaloudis was captivated by its ethereal properties. The material is created by forming a gel from a polymer and solvent, then flash-drying it under pressure to produce a solid filled with microscopic pores.

Scientists at JPL chose aerogel in the mid-1990s to enable the Stardust mission, with the idea that a porous surface could capture particles while flying on a probe behind a comet. Aerogel worked in lab tests, but it was difficult to manufacture consistently and needed to be made space-worthy. NASA JPL hired materials scientist Steve Jones to develop a flight-ready  aerogel, and he eventually got funding for an aerogel lab.

The Stardust mission succeeded, and when Michaloudis heard of it, he reached out to JPL, where Jones invited him to the lab. Now retired, Jones recalled, “I went through the primer on aerogel with him, the different kinds you could make and their different properties.” The size of Jones’ reactor, enabling it to make large objects, impressed Michaloudis. With tips on how to safely operate a large reactor, he outfitted his own lab with one.

In India, Michaloudis learned recipes for aerogels that can be molded into large objects and don’t crack or shrink during drying. His continued work with aerogels has created an extensive art portfolio.

Michaloudis has had more than a dozen solo exhibitions. All his artwork involves aerogel, drawing attention with its unusual qualities. An ethereal, translucent blue, it casts an orange shadow and can withstand molten metals.

In 2020, Michaloudis created a quartz-encapsulated aerogel pendant for the centerpiece of that year’s collection from French jewelry house Boucheron. Michaloudis also captured the fashion and design world’s attention with a handbag made of aerogel, unveiled at Coperni’s 2024 fall collection debut.

NASA was a crucial step along the way. “I am what I am, and we made what we made thanks to the Stardust project,” said Michaloudis.

For more information: NASA

Image: The Jet Propulsion Laboratory perfected aerogel for the Stardust mission. Under Stardust, bricks of aerogel covered panels on a spacecraft that flew behind a comet, with the microporous material “soft catching” any particles that might strike it and preserving them for return to Earth.

Indian scientists find ‘quantum fingerprint’ for exotic materials

Scientists at the Raman Research Institute have made a breakthrough in quantum materials by discovering a novel method to identify a key property called a topological invariant—an unchanging characteristic even when a material is deformed. This property is essential for understanding the unusual behaviors of topological materials, which are foundational to future technologies like quantum computing, fault-tolerant electronics, and energy-efficient systems. Historically, detecting these unique traits has been a major challenge, making this advancement a significant step forward in the field.

To grasp the concept of topological invariance, scientists often use the analogy of a “vada” (South Indian snack) and a coffee cup. Both have a single hole, making them topologically equivalent – one can be continuously deformed into the other without cutting or gluing. In contrast, a vada and an “idli” (steamed rice cake) are not topologically equivalent, as they possess different numbers of holes, making continuous deformation impossible. This fundamental idea of “counting holes” is key to unlocking the hidden properties within these exotic materials.

In materials such as topological insulators and superconductors, electrons exhibit unusual behavior directly influenced by the material’s quantum “shape.” These shapes are defined not by their physical appearance but by deeper, intrinsic topological invariants, such as winding numbers in one-dimensional systems or Chern numbers in two-dimensional systems. These numbers act as a kind of hidden code, dictating how particles move through the material.

The RRI team, led by Professor Dibyendu Roy and PhD researcher Kiran Babasaheb Estake, has found an innovative method to detect this hidden code using a property called the spectral function. This function acts as a “quantum fingerprint,” providing insights into how energy and particles behave within the material. Their research specifically focused on analyzing the momentum-space spectral function (SPSF).

Traditionally, researchers relied on techniques like angle-resolved Photoemission Spectroscopy (ARPES) to study electron behaviour. The groundbreaking new research, recently published in Physical Review B, demonstrates that the same spectral function holds the keys to unlocking a material’s hidden topology. This offers a revolutionary way to “see” the underlying structure without direct observation.

“The spectral function has been used for many years as an experimental tool to probe physical quantities such as the density of states and the dispersion relation of electrons in a system through ARPES. It was not seen as a tool to probe topology or topological aspects of an electronic system,” stated Kiran Babasaheb Estake, a PhD student in theoretical Physics at RRI and the lead author of the study.

He added, “We have demonstrated through various examples that the spectral function also contains signatures about a system’s topology.”

This study potentially offers a universal tool for exploring and classifying topological materials. Its implications could pave the way for new discoveries in condensed matter physics, ultimately benefiting the development of quantum computers,next-generation electronics, and more energy-efficient systems.

For more information: Raman Research Institute
Image: Representation of what is topological equivalence

Smart phonon control boosts efficiency in eco-friendly thermoelectric material

Researchers have significantly improved the efficiency of β-Zn₄Sb₃, a thermoelectric material that converts waste heat into electricity, without using rare or costly elements. This tellurium-free compound was studied using advanced neutron scattering techniques, revealing that tiny heat vibrations—called phonons—were being disrupted by “rattling” atoms within the crystal structure. This effect, known as phonon avoided crossing, greatly reduces heat transfer through the material, enhancing its energy-harvesting capabilities.

Thanks to this effect, the material’s thermal conductivity dropped to extremely low levels—great news for thermoelectric performance. Even better, the researchers found that the single-crystal version of this material also conducts electricity better than its polycrystalline counterpart, reaching a high power conversion efficiency of 1.4%.

These results show that smart phonon control can lead to high-performance, eco-friendly materials for converting heat into power.

In thermoelectric materials, avoided crossing refers to the interaction between propagating phonons and localized vibrational modes, where their energy dispersions repel each other rather than intersect. This phenomenon occurs under specific conditions, such as crystal symmetries or vibrational mode couplings.

However, when researchers developed the single-crystal β-Zn4Sb3, they observed an unexpected, avoided crossing, revealing unique phonon behavior that deviated from conventional thermoelectric materials.

The article explores the thermoelectric performance of single-crystalline β-Zn4Sb3, a tellurium-free material, by uncovering the microscopic mechanisms that lead to its ultralow lattice thermal conductivity (κL).

Using inelastic neutron scattering (INS), the researchers provide the first experimental observation of avoided crossing between longitudinal acoustic phonons and low-energy rattling modes. This interaction causes a significant reduction in phonon group velocity—from over 4000 m/s to about 591 m/s—and shortens phonon lifetimes to under 1 picosecond, both of which contribute to strongly suppressed heat transport.

The β-Zn4Sb3 single crystal achieves a κL of approximately 0.36 W/m·K in the 300–600 K range and a peak thermoelectric figure of merit (zT) of 1.0 at 623 K. Additionally, device-level testing shows a conversion efficiency (η) of 1.4% in a single-leg thermoelectric module—one of the highest reported for undoped Zn4Sb3.

Structural characterizations via TEM reveal a grain-boundary-free lattice with uniformly distributed moiré fringes, attributed to Zn concentration variations.

These nanoscale features further enhance phonon scattering without degrading electronic performance. Compared to polycrystalline samples, the single crystal exhibits significantly better electrical conductivity due to fewer defects and optimized carrier mobility.

“This discovery shows how heat flow can be engineered to design more efficient and sustainable energy technologies—without depending on scarce resources,” says Prof. Hsin-Jay Wu.

For more information: Advanced Science

Image: Phonon dispersion map single crystalline β-Zn4Sb3 of at 300 K, measured in the longitudinal scan along [hh0]. Credit: National Taiwan University

US scientists discover new 2D material that could be used in electrochemical energy tech

Nearly a decade ago, scientists predicted that boron atoms would bond too tightly to copper to form borophene—a promising, flexible, metallic 2D material with potential in electronics, energy, and catalysis. New research led by Rice University’s Boris Yakobson confirms this prediction, but in an unexpected way, offering fresh insights into the elusive material. Yakobson emphasized that since borophene remains on the edge of existence, every new discovery about it significantly advances our understanding of materials science, physics, and electronics.

“Our very first theoretical analysis warned that on copper, boron would bond too strongly, and even if borophene did form, it would be hopelessly attached to the substrate. Now, more than a decade later, it turns out we were right ⎯ and the result is not borophene, but something else entirely,” said Yakobson.

Researchers revealed that unlike systems such as graphene on copper, where atoms may diffuse into the substrate without forming a distinct alloy, the boron atoms in this case formed a defined 2D copper boride ⎯ a new compound with a distinct atomic structure. The finding sets the stage for further exploration of a relatively untapped class of 2D materials, according to researchers.

The research reveals that since the first realization of borophene on Ag(111), two-dimensional (2D) boron nanomaterials have attracted substantial interest because of their polymorphic diversity and potential for hosting solid-state quantum phenomena.

“Here, we use atomic-resolution scanning tunneling microscopy (STM) and field-emission resonance (FER) spectroscopy to elucidate the structure and properties of atomically thin boron phases grown on Cu(111). Specifically, FER spectroscopy reveals charge transfer and electronic states that strongly differ from the decoupled borophene phases observed on silver, suggesting that the deposition of boron on copper results in strong covalent bonding characteristic of a 2D copper boride,” said researchers.

Earlier, studies synthesized borophene on metals like silver and gold, but copper remained an open ⎯ and contested ⎯ case. Some studies also highlighted that the boron might form polymorphic borophene on copper, while others suggested it could phase-separate into borides or even nucleate into bulk crystals.

Researchers revealed that resolving these possibilities required a uniquely detailed investigation combining high-resolution imaging, spectroscopy and theoretical modeling.

Yakobson underlined that what experimentalists first saw were rich patterns of atomic resolution images and spectroscopy signatures, which required a lot of hard work of interpretation.

These efforts revealed a periodic zigzag superstructure and distinct electronic signatures, both of which deviated significantly from known borophene phases. A strong match between experimental data and theoretical simulations helped resolve a debate about the nature of the material that forms at the interface between the copper substrate and the near-vacuum environment of the growth chamber, according to a press release.

“2D copper boride is likely to be just one of many 2D metal borides that can be experimentally realized,” said Mark Hersam, Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University and a co-corresponding author on the study.

“We look forward to exploring this new family of 2D materials that have broad potential use in applications ranging from electrochemical energy storage to quantum information technology.”

For more information: Science Advances

Image: Calculated charge redistribution in copper boride (Cu8B14), where teal represents charge depletion and yellow represents charge accumulation.

These contacts let you see in the dark with your eyes closed

Scientists have developed innovative contact lenses that allow both humans and mice to see infrared light by converting it into visible colors—without the need for bulky equipment or batteries. These transparent lenses enable users to perceive both regular and infrared light simultaneously and can detect multiple infrared wavelengths at once. Remarkably, the lenses perform even better with eyes closed due to infrared light’s superior penetration. In tests, mice avoided infrared light, and humans could interpret flickering codes and light directions, showcasing the lenses’ potential for practical applications.

“Our research opens up the potential for non-invasive wearable devices to give people super-vision,” says senior author Tian Xue, a neuroscientist at the University of Science and Technology of China. “There are many potential applications right away for this material. For example, flickering infrared light could be used to transmit information in security, rescue, encryption or anti-counterfeiting settings.”

The lenses use specially engineered nanoparticles that absorb invisible infrared light and convert it into light our eyes can see, typically in the 400 to 700 nanometer range. More specifically, the technology targets near-infrared light, which lies just beyond human vision, in the 800 to 1600 nanometer range.

In earlier studies, the team showed these particles could give mice infrared vision when injected directly into the eye. This time, they’ve achieved similar results using a much less invasive approach—by building the particles right into soft contact lenses.

To create the contact lenses, the team combined the nanoparticles with flexible, non-toxic polymers that are used in standard soft contact lenses. After showing that the contact lenses were non-toxic, they tested their function in both humans and mice.

They found that contact lens-wearing mice displayed behaviors suggesting that they could see infrared wavelengths. For example, when the mice were given the choice of a dark box and an infrared-illuminated box, contact-wearing mice chose the dark box whereas contact-less mice showed no preference. The mice also showed physiological signals of infrared vision: the pupils of contact-wearing mice constricted in the presence of infrared light, and brain imaging revealed that infrared light caused their visual processing centers to light up.

In humans, the infrared contact lenses enabled participants to accurately detect flashing morse code-like signals and to perceive the direction of incoming infrared light. “It’s totally clear cut: without the contact lenses, the subject cannot see anything, but when they put them on, they can clearly see the flickering of the infrared light,” said Xue.

“We also found that when the subject closes their eyes, they’re even better able to receive this flickering information, because near-infrared light penetrates the eyelid more effectively than visible light, so there is less interference from visible light.”

An additional tweak to the contact lenses allows users to differentiate between different spectra of infrared light by engineering the nanoparticles to color-code different infrared wavelengths. For example, infrared wavelengths of 980 nm were converted to blue light, wavelengths of 808 nm were converted to green light, and wavelengths of 1,532 nm were converted to red light. In addition to enabling wearers to perceive more detail within the infrared spectrum, these color-coding nanoparticles could be modified to help color blind people see wavelengths that they would otherwise be unable to detect.

“By converting red visible light into something like green visible light, this technology could make the invisible visible for color blind people,” says Xue.

Because the contact lenses have limited ability to capture fine details (due to their close proximity to the retina, which causes the converted light particles to scatter), the team also developed a wearable glass system using the same nanoparticle technology, which enabled participants to perceive higher-resolution infrared information.

Currently, the contact lenses are only able to detect infrared radiation projected from an LED light source, but the researchers are working to increase the nanoparticles’ sensitivity so that they can detect lower levels of infrared light.

“In the future, by working together with materials scientists and optical experts, we hope to make a contact lens with more precise spatial resolution and higher sensitivity,” says Xue.

For more information: Cell

Robotic touch sensors are not just skin deep

Researchers at Northwestern University and Tel Aviv University have addressed a key challenge in developing affordable robotic touch by identifying a flaw in the materials used for robotic skin. They discovered that inexpensive silicone rubber composites form insulating layers on their surfaces, which block electrical contact between the sensing polymer and electrodes, leading to inaccurate readings. By eliminating this issue, the team has paved the way for low-cost robotic skins capable of mimicking human touch—enabling robots to detect curves and edges for more precise object handling.

“A lot of scientists misunderstand their sensor response because they lump together the behavior of the contacts with the behavior of the sensor material, resulting in inconsistent data,” Grayson said. “It turns out, if you are not aware of this problem, you can publish papers which no one can reproduce. Our work identifies the exact problem, quantifies its extent both microscopically and electrically, and gives a clear step-by-step trouble-shooting manual to fix the problem.”

The rubber that can be used for typical robotic skin, called an elastomer, is flexible, lightweight and inexpensive, and when electrically conducting fillers like carbon nanotubes are added to the mix, the resulting composite becomes an ideal candidate for a touch sensor, whose resistance changes locally when pressed. But to receive electrical signals, the sensors need to be electrically contacted, and the researchers detected a thin insulating layer ever-present in such composites which could drastically change the behavior of the contacts. Just by sanding down the ultrathin insulation layer, the team was able to achieve a much stronger electrical contact and calibrate the thickness of the insulating layer both electrically and microscopically.

“All interesting things happen at the interface,” said co-author and professor at Tel Aviv University Noa Lachman. “This publication not only shows the importance of sensor interfaces, but also the importance of working at the nexus between two different disciplines: materials science and electrical engineering. Materials experts suspected the presence of this insulating external layer in conductive polymer composites for years but couldn’t understand its electrical effects. Each of us has one piece of the puzzle, but only together can we get the whole picture.”

Robotics in particular can be tricky in part because it requires so many types of expertise. The polymer materials scientist designing the functional electronic material for a robot, for example, does not have the same training and skills as the electrical engineer whose electronics will process the sensor signals. Grayson said the “contact preparation” challenge was precisely where the conversation about this research began.

“That’s why our collaboration with Tel Aviv is essential – they know the materials science that we don’t know,” Grayson said. “We rely on them to prepare the materials we are studying, then we take and study the material before turning around to help the Tel Aviv materials scientists characterize their materials better.”

Producing new materials — and then reproducing them — requires consistency across many different variables that are often difficult or even impossible to control. In exposing the question of reproducibility in much of the literature on touch sensing, Grayson challenges the research community to hold itself to a higher standard with the quality check described in the paper. As awareness of this problem spreads among researchers, new publications can be more rigorously relied upon to advance the field with new capabilities.

For more information: Journal of Advanced Electronic Materials

Machine learning powers new approach to detecting soil contaminants

Researchers at Rice University and Baylor College of Medicine have developed a novel method to detect hazardous soil pollutants, including previously unstudied compounds, using a combination of light-based imaging, theoretical predictions of molecular light signatures, and machine learning algorithms. This technique enables the identification of toxic substances like polycyclic aromatic hydrocarbons (PAHs) and their derivatives (PACs)—common combustion by-products linked to cancer and developmental issues—without the need for physical reference samples or advanced lab facilities, overcoming a major limitation in traditional soil contamination analysis.

“This method makes it possible to identify chemicals that have not yet been isolated experimentally,” said Naomi Halas, University Professor and the Stanley C. Moore Professor of Electrical and Computer Engineering at Rice.

The new method uses a light-based imaging technique known as surface-enhanced Raman spectroscopy, which analyzes how light interacts with molecules, tracking the unique patterns, or spectra, they emit. Spectra serve as “chemical fingerprints” for each compound. The technique is refined through the use of signature nanoshells designed to enhance relevant traits in the spectra.

Using density functional theory ⎯ a computational modeling technique that can predict how atoms and electrons behave in a molecule ⎯ the researchers calculated what the spectra of a whole range of PAHs and PACs look like based on the compounds’ molecular structure. This allowed them to generate a virtual library of “fingerprints” for PAHs and PACs.

Two complementary ML algorithms ⎯ characteristic peak extraction and characteristic peak similarity ⎯ were used to parse relevant spectral traits in real-world soil samples and match them to compounds mapped out in the virtual library of spectra.

“We are using PAHs in soil to illustrate this very important new strategy,” Halas said. “There are tens of thousands of PAH-derived chemicals and this approach ⎯ calculating their spectra and using machine learning to connect the theoretically calculated spectra to those observed in a sample ⎯ allows us to identify chemicals that we may not, or do not, have any experimental data for.”

The method addresses a critical gap in environmental monitoring, opening the door to identifying a much broader range of hazardous compounds ⎯ including those that have changed over time. This is especially important given that soil is a dynamic environment where chemicals are subject to transformations that can render them harder to detect.

Thomas Senftle, Rice’s William Marsh Rice Trustee Associate Professor of Chemical and Biomolecular Engineering, compared the process to using facial recognition in order to find an individual in a crowd.

“You can imagine we have a picture of a person when they’re a teenager, but now they’re in their 30s,” Senftle said. “In my group what we do is, on the theory side, we can predict what the picture will look like.”

The researchers tested the method on soil from a restored watershed and natural area using both artificially contaminated samples and a control sample. Results showed the new approach reliably picked out even minute traces of PAHs using a simpler and faster process than conventional techniques.

“This method can identify lesser-known and largely unstudied PAH and PAC pollutant molecules,” said Oara Neumann, a Rice research scientist who is a co-author on the study.

In the future, the method could enable on-site field testing by integrating the ML algorithms and theoretical spectral library with portable Raman devices into a mobile system, making it easier for farmers, communities and environmental agencies to test soil for hazardous compounds without needing to send samples to specialized labs and wait days for results.

Ankit Patel, assistant professor of electrical and computer engineering at Rice and assistant professor of neuroscience at BCM, is a corresponding author on the study alongside Halas.

Other Rice co-authors include computer science doctoral alum Yilong Ju; doctoral students Sarah Denison, Peixuan Jin and Andres Sanchez-Alvarado; Peter Nordlander, the Wiess Chair in Physics and Astronomy and professor of electrical and computer engineering and materials science and nanoengineering; and Pedro Alvarez, the George R. Brown Professor of Civil and Environmental Engineering.

For more information: Proceedings of the National Academy of Sciences

Image: Naomi Halas and Ankit Patel

Tapping a new toolbox, engineers buck tradition in high-performing heat exchanger

Engineers at the University of Wisconsin–Madison have developed a high-performance, twisty high-temperature heat exchanger using a combination of topology optimization and advanced 3D metal printing. This innovative design significantly outperforms traditional straight-channel heat exchangers in terms of heat transfer, power density, and overall effectiveness. These heat exchangers are critical in industries such as aerospace, power generation, and aviation, where efficient heat dissipation is essential.

“Traditionally, heat exchangers flow hot fluid and cold fluid through straight pipes, mainly because straight pipes are easy to manufacture,” says Xiaoping Qian, a professor of mechanical engineering at UW–Madison. “But straight pipes are not necessarily the best geometry for transferring heat between hot and cold fluids.”

Additive manufacturing enables researchers to create structures with complex geometries that can yield more efficient heat exchangers. Given this design freedom, Qian set out to discover a design for the hot and cold fluid channels inside a heat exchanger that would maximize heat transfer.

He harnessed his expertise in topology optimization, a computational design approach used to study the distribution of materials in a structure to achieve certain design goals. He also incorporated a patented technique, called projected undercut perimeter, that considers manufacturability constraints for the overall design.

With an optimized design in hand, Qian worked with colleague Dan Thoma, a professor of materials science and engineering at UW–Madison, who led the 3D printing of the heat exchanger using a metal additive manufacturing technique called laser powder bed fusion.

From the outside, the optimized heat exchanger looks identical to a traditional version with a straight channel design—but their internal core designs are strikingly different. The optimized design has intertwining hot and cold fluid channels with intricate geometries and complex surface features. These complex geometric features guide fluid flow in a twisting path that enhances the heat transfer.

Collaborator Mark Anderson, a professor of mechanical engineering at UW–Madison, conducted thermal-hydraulic tests on the optimized heat exchanger and a traditional heat exchanger to compare their performance.

The optimized design was not only more effective in transferring heat but also achieved a 27% higher power density than the traditional heat exchanger. That higher power density enables a heat exchanger to be lighter and more compact—useful attributes for aerospace and aviation applications.

While previous research has used topology optimization to study two-fluid heat exchanger designs, Qian says this work is the first to harness topology optimization and impose manufacturability constraints to ensure the design can be built and tested.

“Optimizing design on the computer is one thing, but to actually make and test it is a very different thing,” Qian says.

“It’s exciting that our optimization method worked. We were able to actually manufacture our heat exchanger design. And, through experimental testing, we demonstrated the performance enhancement of our optimized design. The excellent work performed by the students, postdoctoral researchers and scientists in the three research groups made this advance possible.”

Sicheng Sun, a recent Ph.D. graduate from Qian’s research group, is the first author on the paper. Additional co-authors include Tiago Augusto Moreira, Behzad Rankouhi, Xinyi Yu and Ian Jentz, all from UW–Madison.

The researchers patented their projected undercut perimeter technique through the Wisconsin Alumni Research Foundation.

For more information: International Journal of Heat and Mass Transfer.

Image: A rendering of a topologically optimized unit cell for a heat exchanger core. The optimized design has hot and cold fluid channels with intricate geometries and complex surface features.

Researchers uncover why cracks in materials break their symmetry while spreading

All materials, including those in our bodies and the structures around us, contain tiny imperfections like cracks, which can sometimes spread suddenly and dangerously—but also form fascinating patterns. Physicists have long struggled to explain why these cracks often branch unpredictably and slow down. However, two recent studies from the Weizmann Institute of Science have revealed that despite their chaotic appearance, crack propagation follows specific physical parameters that govern their behavior and explain the emergence of asymmetrical patterns.

Decades of controlled experiments in material failure have shown that even when a perfectly symmetrical crack is created under tensile forces, it spontaneously loses symmetry as it propagates, veering off course and moving more slowly than expected.

“These observations are the exact opposite of what we would expect based on theoretical calculations, which predict that even if we introduce a small obstacle in the path of a symmetrical crack under tension, the crack should return to a smooth, symmetrical trajectory,” says Prof. Eran Bouchbinder.

“Given the experimental evidence, we assumed that there must be missing links—overlooked physical properties that could account for the observed behavior.”

In one of the two studies led by Dr. Yuri Lubomirsky, then a doctoral student in Bouchbinder’s group in Weizmann’s Chemical and Biological Physics Department, the researchers used a computer model to simulate the propagation of cracks in three-dimensional materials.

“To understand crack propagation, we focused on the crack tip—the point where the material transitions from intact to fractured,” explains Lubomirsky. “While moderate conditions prevail throughout most of the material most of the time—meaning its behavior can often be understood by averaging its properties—the crack tip is governed by extreme conditions.

“Physical quantities such as force, temperature and velocity are so large there that they can be mathematically treated as approaching infinity, and the usual physical rules no longer apply. We postulated that the crack tip might reveal the hidden properties that explain asymmetrical crack propagation.”

The researchers’ arduous seven-year search for these missing physical properties was at times frustrating. “Ultimately, the breakthrough came from introducing significant disorder into the simulations—a factor previously overlooked in dynamic theories of material failure.

“We ran numerous simulations using advanced computing capabilities and observed that the crack initially moves straight until it reaches a point where it splits locally and then changes direction,” Bouchbinder says.

“The challenge was to extract from the vast amount of data the basic principle explaining why the crack branches out and deviates from a smooth, symmetrical path. One day, I asked Yuri to cross-reference two graphs, and that’s when it clicked: The intrinsic disorder of real-world materials, combined with the extreme conditions at the crack tip, turned out to be the missing link.”

The laws of physics explain the behavior of uniform materials fairly well, but most materials in the world are not truly uniform. Glass, for example, appears smooth and homogeneous, but a closer look at its particles and the connections between them reveals a structure lacking consistent order. This means that the internal forces acting within glass vary from one region to another.

Until now, engineers and scientists trying to understand fracture dynamics had relied on averaged material properties and thus failed to explain why cracks break symmetry. Bouchbinder and Lubomirsky realized that the answer lies in the extent of internal disorder—that is, how much the material’s strength varies from place to place.

The researchers applied varying fracture forces to their computer model and studied the relationship between crack propagation and material disorder. They observed that when fracture forces were weak, cracks propagated symmetrically without branching and were largely unaffected by disorder.

However, when fracture forces were moderate, cracks became sensitive to disorder: When the crack tip reached a weaker region, local instabilities developed, causing the crack to split locally instead of continuing in a straight line. These local branches competed with each other—one branch would stall while the other would continue as the main crack, often changing direction.

Retrospective examination of these regions revealed microcracks where the secondary branches had been arrested. In other words, in this regime the extent of branching depended directly on the degree of disorder.

Finally, when fracture forces exceeded a critical threshold, the crack no longer halted at points of instability but split into entirely separate branches that widened and penetrated deeper into the material. In this high-force regime, disorder once again played a minor role.

The deviation of cracks from their symmetry axis and the formation of branches come at an energetic cost: A larger amount of material is broken, and the crack’s velocity decreases relative to the speed it would have reached had it remained smooth and symmetrical.

Another phenomenon commonly seen in cracks—also linked to symmetry breaking—is the formation of steps composed of two interacting fracture surfaces. In a follow-up study the researchers investigated how this pattern forms.

They found that step formation depends not only on the degree of internal disorder but also on external tensile forces’ slight deviations from perfect symmetry. In addition to the tensile forces that open the crack, there are almost always perpendicular forces causing the crack’s faces to slide past each other in a rotational motion.

Incorporating both types of force and the internal disorder into their mathematical model, the scientists succeeded in predicting and explaining the emergence of the step pattern.

“These discoveries provide a physical and mathematical framework for understanding material failure through crack dynamics that we encounter in everyday life,” says Bouchbinder.

Lubomirsky adds, “Our findings could also help in designing materials that are more resilient to catastrophic cracking. We show that increasing disorder can slow crack propagation—an insight that could have significant implications for the design of structures and physical systems.

“Natural materials such as bones and teeth have evolved to resist failure, and it’s possible that their internal disorder is one of the key factors behind their resilience. This is where our findings also shed new light on the workings of nature.”

For more information: Nature Communications

Image: The crack driving force as a function of its propagation velocity in 2D and 3D, under different levels of disorder, and the emergence of a limiting crack velocity.

$11.5 million sponsorship creates new research institute

Epsilon Group, India, a leading innovator in carbon black and advanced battery materials for electric vehicles and energy storage, is partnering with Tufts University in Massachusetts to launch the Tufts Epsilon Materials Institute-a new research center made possible by an $11.5 million sponsorship and dedicated to advancing materials science and engineering for global energy and sustainability solutions.

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New spectroscopy technique extends device lifespan

High-resolution, full-color display devices like foldable smartphones and ultrathin televisions use organic light-emitting diodes (OLEDs) due to their flexibility, self-illumination, lightweight construction, ultra-thin profiles, high contrast ratios, and low-voltage operation. An OLED consists of multiple ultrathin organic film layers between two electrodes, each layer playing a specific role in the device’s operation. When voltage is applied, electrical charges accumulate and emit light at the interfaces between these layers. While this multilayer structure allows precise control of charge accumulation, transport, and light generation, it also leads to degradation of the organic layers over time, limiting the lifespan and efficiency of OLED devices.

Understanding how the electronic structure at these interfaces behaves during operation remains a significant challenge. To tackle this issue, Professor Takayuki Miyamae, together with Mr. Tatsuya Kaburagi and Dr. Kazunori Morimoto from Chiba University in Japan, employed a second-order nonlinear spectroscopic method known as sum-frequency generation (SFG). This technique enabled them to investigate the vibrational and electronic properties at the interfaces within operating OLEDs, offering new insights into their behavior under real-world conditions.

When voltage is applied to an OLED system, light is emitted via the recombination of charges at the organic interfaces. This alters the SFG output, allowing researchers to study how charge accumulates and what electronic structural changes occur at the interfaces under different operating conditions.

three different multilayer OLEDs with different types and combinations of organic layers were used. Electronic SFG (ESFG) spectroscopy was conducted on three OLED devices to examine spectral changes induced by the charge behavior and electronic structure at the interfaces. “We examined the differences in the electric field intensities inside the OLED devices based on the applied voltage dependence of the ESFG spectra. This clarifies the role of field strength differences that affect the ease of internal charge flow and the light emission characteristics for the first time,” explains Prof. Miyamae about the team’s study.

ESFG spectral bands corresponding to each organic layer were identified by comparing the absorption spectra and layer configurations among the three OLED devices. The researchers observed changes in spectral signal intensities when applying voltages to the OLED devices, which were related to the changes in the electric field and charge behavior inside the OLEDs.

Upon voltage application, the spectral signal intensity increased at the absorption band of the hole transport material (positive charge carriers inside the OLED), and signal intensity decreased at the absorption band of the light-emitting layer. This shows that internal charge flow across the organic layers within the OLEDs is different, leading to changes in spectra.

The team also applied square-wave pulse voltages on these devices to study how electric fields formed within these devices varied with time. They found that adding BAlq (a material used for electron transport in OLEDs) changes the position where the light is emitted in OLEDs. This shift in emission affects both the color and shape of the emitted light and how efficiently the device converts electricity into light.

“ESFG technique represents a novel, highly effective, nondestructive, and non-invasive spectroscopic approach for examining the electric field generation caused by injected charges in solid-state thin-film devices,” notes Prof. Miyamae about this innovative research work.

With this technique, material scientists can now design OLEDs with improved device lifetimes, energy efficiency, and cost reductions, eventually increasing the use of ultrathin organic devices in our everyday lives. “Moreover, this research can greatly shorten and rationalize materials development research, which now performs trial-and-error processes and long periods of degradation verification to assess device efficiency and lifetime,” adds Prof. Miyamae.

For more information: Journal of Materials Chemistry C

Fujitsu and RIKEN develop world-leading 256-qubit superconducting quantum computer

Fujitsu Limited and RIKEN have developed a cutting-edge 256-qubit superconducting quantum computer at the RIKEN RQC-FUJITSU Collaboration Center, building on the 64-qubit version launched in October 2023 with support from Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT). This advancement incorporates high-density implementation techniques, marking a significant step toward practical applications of superconducting quantum computers to address complex global issues. Starting in the first quarter of fiscal 2025, the 256-qubit quantum computer will be integrated into a hybrid quantum computing platform and offered to companies and research institutions worldwide, enabling more complex analyses and sophisticated error correction algorithms.

Moving forward, both organizations will further enhance the platform’s usability by working to enable seamless collaboration between quantum and classical computers, enabling the efficient execution of hybrid quantum-classical algorithms.

Fujitsu and RIKEN’s 256-qubit superconducting quantum computer overcomes some key technical challenges, including appropriate cooling within the dilution refrigerator which is achieved through the incorporation of high-density implementation and cutting-edge thermal design. Other key features include:

1. Scalable 3D connection structure

  • Enables efficient scaling of qubit count without requiring complex redesigns by arranging 4-qubit unit cells in a 3D configuration
  • The 256-qubit machine utilizes the same unit cell design established in its 64-qubit predecessor, effectively demonstrating the scalability of this architectural approach

2. Quadrupled implementation density within dilution refrigerator

  • Quadrupled implementation density achieved within the dilution refrigerator, allowing the 256-qubit machine to operate within the same cooling unit as the 64-qubit system
  • Highly optimized design that carefully balances heat generation from control circuits with the cooling capacity of the refrigerator, while maintaining the necessary ultra-high vacuum and extremely low temperatures

Fujitsu is committed to accelerating the practical application of quantum computers from both hardware and software perspectives. Through its platform for hybrid quantum computing, Fujitsu will provide larger-scale quantum computers to global companies and research institutions conducting joint research in various fields, including finance and drug discovery.

Fujitsu and RIKEN will continue R&D efforts toward the launch of a 1,000-qubit computer, which is scheduled to be installed in a new building at Fujitsu Technology Park in 2026. In addition, the two organizations will extend the installation period of their Collaboration Center from March 2025 to March 2029, and will continue to work on the long-term R&D of technologies that will enable the realization of even larger superconducting quantum computers.

For more information: Fujitsu

Image: Newly developed 256-qubit superconducting quantum computer