New brain-like transistor mimics human intelligence

An artistic interpretation of brain-like computing.
Illustration Credit: Xiaodong Yan/Northwestern University

Taking inspiration from the human brain, researchers have developed a new synaptic transistor capable of higher-level thinking.

Designed by researchers at Northwestern University, Boston College and the Massachusetts Institute of Technology (MIT), the device simultaneously processes and stores information just like the human brain. In new experiments, the researchers demonstrated that the transistor goes beyond simple machine-learning tasks to categorize data and is capable of performing associative learning.

Although previous studies have leveraged similar strategies to develop brain-like computing devices, those transistors cannot function outside cryogenic temperatures. The new device, by contrast, is stable at room temperatures. It also operates at fast speeds, consumes very little energy and retains stored information even when power is removed, making it ideal for real-world applications.

“The brain has a fundamentally different architecture than a digital computer,” said Northwestern’s Mark C. Hersam, who co-led the research. “In a digital computer, data moves back and forth between a microprocessor and memory, which consumes a lot of energy and creates a bottleneck when attempting to perform multiple tasks at the same time. On the other hand, in the brain, memory and information processing are co-located and fully integrated, resulting in orders of magnitude higher energy efficiency. Our synaptic transistor similarly achieves concurrent memory and information processing functionality to more faithfully mimic the brain.”

RIT researchers develop new technique to study how cancer cells move

Vinay Abhyankar, right, assistant professor of biomedical engineering, works closely with two doctoral students, Mehran Mansouri, left, and Indranil Joshi, on research to assess cancer cell migration processes.
Photo Credit: A. Sue Weisler/RIT

In tumors, cells follow microscopic fibers, comparable to following roads through a city. Researchers at the Rochester Institute of Technology developed a new technique to study different features of these “fiber highways” to provide new insights into how cells move efficiently through the tumor environment.

The study, published in the journal Advanced Functional Materials, focused on contact guidance, a process where migrating cells follow aligned collagen fibers. Understanding this process is crucial, as it plays a key role in cancer metastasis, the spread of cancer to other parts of the body.

“Previous research on contact guidance, a process where cancer cells migrate along aligned collagen fibers, has been largely studied in collagen gels with uniform fiber alignment,” said Vinay Abhyankar, associate professor of biomedical engineering in RIT’s Kate Gleason College of Engineering, and study co-author. “However, the tumor microenvironment also features subtle variations or gradients in fiber alignment, and their role in cell migration has been largely unexplored. We suspected that alignment gradients could efficiently direct cell movement but lacked the technology to test the hypothesis.”

Aerogel can become the key to future terahertz technologies

Aerogel can obtain high hydrophobicity by simple chemical modifications.
Photo Credit: Thor Balkhed

High-frequency terahertz waves have great potential for a number of applications including next-generation medical imaging and communication. Researchers at Linköping University, Sweden, have shown, in a study published in the journal Advanced Science, that the transmission of terahertz light through an aerogel made of cellulose and a conducting polymer can be tuned. This is an important step to unlock more applications for terahertz waves.

The terahertz range covers wavelengths that lie between microwaves and infrared light on the electromagnetic spectrum. It has a very high frequency. Thanks to this, many researchers believe that the terahertz range has great potential for use in space exploration, security technology and communication systems, among other things. In medical imaging, it can also be an interesting substitute for X-ray examinations as the waves can pass through most non-conductive materials without damaging any tissue.

However, there are several technological barriers to overcome before terahertz signals can be widely used. For example, it is difficult to create terahertz radiation in an efficient way and materials that can receive and adjust the transmission of terahertz waves are needed.

An Electrifying Improvement in Copper Conductivity

Xiao Li, a materials scientist, holds samples of highly conductive metal wires created on the patented Shear Assisted Processing and Extrusion platform. 
Photo Credit: Andrea Starr | Pacific Northwest National Laboratory

A common carbon compound enables remarkable performance enhancements when mixed in just the right proportion with copper to make electrical wires. It’s a phenomenon that defies conventional wisdom about how metals conduct electricity. The findings, reported December 2023 in the journal Materials & Design, could lead to more efficient electricity distribution to homes and businesses, as well as more efficient motors to power electric vehicles and industrial equipment. The team has applied for a patent for the work, which was supported by the Department of Energy (DOE) Advanced Materials and Manufacturing Technologies Office.

Materials scientist Keerti Kappagantula and her colleagues at DOE’s Pacific Northwest National Laboratory discovered that graphene, single layers of the same graphite found in pencils, can enhance an important property of metals called the temperature coefficient of resistance. This property explains why metal wires get hot when electric current runs through them. Researchers want to reduce this resistance while enhancing a metal’s ability to conduct electricity. For several years they have been asking whether metal conductivity be increased, especially at high temperatures, by adding other materials to it. And if yes, can these composites be viable on a commercial scale?

Now, they’ve demonstrated they can do just that, using a PNNL-patented advanced manufacturing platform called ShAPE™. When the research team added 18 parts per million of graphene to electrical-grade copper, the temperature coefficient of resistance decreased by 11 percent without decreasing electrical conductivity at room temperature. This is relevant for the manufacturing of electric vehicle motors, where an 11 percent increase in electrical conductivity of copper wire winding translates into a 1 percent gain in motor efficiency.

Researchers Find They Can Stop Degradation of Promising Solar Cell Materials

An illustration of metal halide perovskites. They are a promising material for turning light into energy because they are highly efficient, but they also are unstable. Georgia Tech engineers showed in a new study that both water and oxygen are required for perovskites to degrade. The team stopped the transformation with a thin layer of another molecule that repelled water.
Image Credit: Courtesy of Juan-Pablo Correa-Baena

Georgia Tech materials engineers have unraveled the mechanism that causes degradation of a promising new material for solar cells — and they’ve been able to stop it using a thin layer of molecules that repels water.

Their findings are the first step in solving one of the key limitations of metal halide perovskites, which are already as efficient as the best silicon-based solar cells at capturing light and converting it into electricity. They reported their work in the Journal of the American Chemical Society.

“Perovskites have the potential of not only transforming how we produce solar energy, but also how we make semiconductors for other types of applications like LEDs or phototransistors. We can think about them for applications in quantum information technology, such as light emission for quantum communication,” said Juan-Pablo Correa-Baena, assistant professor in the School of Materials Science and Engineering and the study’s senior author. “These materials have impressive properties that are very promising.”

Scientists reveal superconductor with on-off switches

(A) The material used in this study consists of stacked layers of ferromagnetic atoms and superconducting atoms. (B) Applying a small magnetic field induces superconductivity, while (C) low temperatures boost that superconductivity.
Illustration Credit: Courtesy Shua Sanchez, University of Washington

As industrial computing needs grow, the size and energy consumption of the hardware needed to keep up with those needs grows as well. A possible solution to this dilemma could be found in superconducting materials, which can reduce that energy consumption exponentially. Imagine cooling a giant data center full of constantly running servers down to nearly absolute zero, enabling large-scale computation with incredible energy efficiency.

Physicists at the University of Washington and the U.S. Department of Energy’s (DOE) Argonne National Laboratory have made a discovery that could help enable this more efficient future. Researchers have found a superconducting material that is uniquely sensitive to outside stimuli, enabling the superconducting properties to be enhanced or suppressed at will. This enables new opportunities for energy-efficient switchable superconducting circuits. The paper was published in Science Advances.

Superconductivity is a quantum mechanical phase of matter in which an electrical current can flow through a material with zero resistance. This leads to perfect electronic transport efficiency. Superconductors are used in the most powerful electromagnets for advanced technologies such as magnetic resonance imaging, particle accelerators, fusion reactors and even levitating trains. Superconductors have also found uses in quantum computing.

For this emergent class of materials, ‘solutions are the problem’

Alec Ajnsztajn (left) and Jeremy Daum
Photo Credit: Gustavo Raskosky/Rice University

Rice University materials scientists developed a fast, low-cost, scalable method to make covalent organic frameworks (COFs), a class of crystalline polymers whose tunable molecular structure, large surface area and porosity could be useful in energy applications, semiconductor devices, sensors, filtration systems and drug delivery.

“What makes these structures so special is that they are polymers but they arrange themselves in an ordered, repeating structure that makes it a crystal,” said Jeremy Daum, a Rice doctoral student and lead author of a study published in ACS Nano. “These structures look a bit like chicken wire ⎯ they’re hexagonal lattices that repeat themselves on a two-dimensional plane, and then they stack on top of themselves, and that’s how you get a layered 2D material.”

Alec Ajnsztajn, a Rice doctoral alumnus and the study’s other lead author, said the synthesis technique makes it possible to produce ordered 2D crystalline COFs in record time using vapor deposition.

“A lot of times when you make COFs through solution processing, there’s no alignment on the film,” Ajnsztajn said. “This synthesis technique allows us to control the sheet orientation, ensuring that pores are aligned, which is what you want if you’re creating a membrane.”

Ultrafast lasers map electrons 'going ballistic' in graphene, with implications for next-gen electronic devices

Ultrafast Laser Lab.
Photo Credit: KU Marketing Communications

Research appearing in ACS Nano, a premier journal on nanoscience and nanotechnology, reveals the ballistic movement of electrons in graphene in real time.

The observations, made at the University of Kansas’ Ultrafast Laser Lab, could lead to breakthroughs in governing electrons in semiconductors, fundamental components in most information and energy technology.

“Generally, electron movement is interrupted by collisions with other particles in solids,” said lead author Ryan Scott, a doctoral student in KU’s Department of Physics & Astronomy. “This is similar to someone running in a ballroom full of dancers. These collisions are rather frequent — about 10 to 100 billion times per second. They slow down the electrons, cause energy loss and generate unwanted heat. Without collisions, an electron would move uninterrupted within a solid, similar to cars on a freeway or ballistic missiles through air. We refer to this as ‘ballistic transport.’”

Scott performed the lab experiments under the mentorship of Hui Zhao, professor of physics & astronomy at KU. They were joined in the work by former KU doctoral student Pavel Valencia-Acuna, now a postdoctoral researcher at the Northwest Pacific National Laboratory.

Zhao said electronic devices utilizing ballistic transport could potentially be faster, more powerful and more energy efficient.

New Strategy Improves Perovskites' Oxygen Reduction Performance in Hydrogen Fuel Cells

Evidence of calcium leaching during ORR, leading to the high surface area of the LCMO64.
Illustration Credit: ©Hao Li et al.

A research group has reported on a new method to enhance the electrochemical surface area (ECSA) in a calcium-doped perovskite, La0.6Ca0.4MnO3 (LCMO64), thereby overcoming a common bottleneck in the application of perovskite oxides as electrocatalysts in hydrogen fuel cells.

Perovskite oxides exhibit interesting and diverse properties, making them valuable in various technological applications. Their high intrinsic activities also position them as a promising alternative to noble metal catalysts for efficiently catalyzing the oxygen reduction reaction (ORR). However, their application is still hampered by their poor electrical conductivity and low specific surface area.

Researchers Find Way to Weld Metal Foam Without Melting Its Bubbles

Composite metal foam (CMF) components
Image Credit: Courtesy of North Carolina State University

Researchers at North Carolina State University have now identified a welding technique that can be used to join composite metal foam (CMF) components together without impairing the properties that make CMF desirable. CMFs hold promise for a wide array of applications because the pockets of air they contain make them light, strong and effective at insulating against high temperatures.

CMFs are foams that consist of hollow, metallic spheres – made of materials such as stainless steel or titanium – embedded in a metallic matrix made of steel, titanium, aluminum or other metallic alloys. The resulting material is both lightweight and remarkably strong, with potential applications ranging from aircraft wings to vehicle armor and body armor.

In addition, CMF is better at insulating against high heat than conventional metals and alloys, such as steel. The combination of weight, strength and thermal insulation means that CMF also holds promise for use in storing and transporting nuclear material, hazardous materials, explosives and other heat-sensitive materials.

However, in order to realize many of these applications, manufacturers would need to weld multiple CMF components together. And that has posed a problem.

Scientists Have Developed a Powder Model for 3D Printing Magnets

Nanocrystalline materials can serve as raw materials for 3D printing permanent magnets.
Photo Credit: Oksana Meleshchuk

Scientists of the Ural Federal University have described the processes of magnetization reversal of nanocrystalline alloys used as raw materials for 3D printing of magnetic systems. The description of the research and the results have been published in the Journal of Magnetism and Magnetic Materials. 

Permanent magnets are products made of hard magnetic materials capable of maintaining the state of magnetization for a long time. They are used as autonomous sources of magnetic field to convert mechanical energy into electrical energy and vice versa. Applications of permanent magnets include robotics, magnetic resonance imaging, production of wind generators, electric motors, mobile phones, high-quality speakers, home appliances, and hard disk drives.

The use of permanent magnets makes it possible to reduce the dimensions of some products and increase their efficiency. The development of power engineering and robotics, miniaturization of high-tech devices, and electric and hybrid vehicles require an annual increase in the production of permanent magnets and at the same time improvement of their magnetic properties. At the same time, one of the most important tasks in the production of permanent magnets is to increase their coercivity (the value of the external magnetic field strength required for complete demagnetization of a ferro- or ferrimagnetic substance).

Unraveling the Conduction Mechanisms in a Novel Perovskite Oxide

Image Credit: Singkham

Scientists at the Tokyo Institute of Technology (Tokyo Tech), in collaboration with Tohoku University and others, have investigated a unique and promising material for next-generation electrochemical devices: hexagonal perovskite-related oxide Ba7Nb3.8Mo1.2O20.1. They unveiled the material's unique ion-transport mechanisms, something that will pave the way for better dual-ion conductors and a greener future.

Clean energy technologies are the cornerstone of sustainable societies, and solid-oxide fuel cells (SOFCs) and proton ceramic fuel cells (PCFCs) are among the most promising types of electrochemical devices for green power generation. These devices, however, still face challenges that hinder their development and adoption.

Ideally, SOFCs should operate at low temperatures to prevent unwanted chemical reactions from degrading their constituent materials. Unfortunately, most known oxide-ion conductors, a key component of SOFCs, only exhibit decent ionic conductivity at elevated temperatures. As for PCFCs, not only are they chemically unstable under carbon dioxide atmospheres, but they also require energy-intensive, high-temperature processing steps during manufacturing.

Dual-ion conductors, however, offer a solution to these problems. By facilitating the diffusion of both protons and oxide ions, these conductors can achieve high total conductivity at lower temperatures, thereby improving the performance of electrochemical devices. Still, the underlying conducting mechanisms behind this material remain poorly understood.

Atomic dance gives rise to a magnet

Tong Lin (from left), Hanyu Zhu and Jiaming Luo at EQUAL lab.
Photo Credit: Jeff Fitlow/Rice University

Quantum materials hold the key to a future of lightning-speed, energy-efficient information systems. The problem with tapping their transformative potential is that, in solids, the vast number of atoms often drowns out the exotic quantum properties electrons carry.

Rice University researchers in the lab of quantum materials scientist Hanyu Zhu found that when they move in circles, atoms can also work wonders: When the atomic lattice in a rare-earth crystal becomes animated with a corkscrew-shaped vibration known as a chiral phonon, the crystal is transformed into a magnet.

According to a study published in Science, exposing cerium fluoride to ultrafast pulses of light sends its atoms into a dance that momentarily enlists the spins of electrons, causing them to align with the atomic rotation. This alignment would otherwise require a powerful magnetic field to activate, since cerium fluoride is naturally paramagnetic with randomly oriented spins even at zero temperature.

Detecting nuclear materials using light

Sandia National Laboratories researcher Patrick Feng, left, and Former Sandian Joey Carlson, right, hold Organic Glass Scintillators they helped create to detect radioactive materials.
Photo Credit: Randy Wong

Blueshift Optics, owned by former Sandia employee Joey Carlson, is working to shift the way radioactive materials are detected, using technology that he helped create at Sandia National Laboratories.

Radiation detection has long been a critical aspect of national security and efforts to make the world safer.

“Agencies are trying to cast this wide net to catch nuclear smuggling, and this is one aspect of that effort,” said Sandia materials scientist Patrick Feng. “You could use this technology at a border crossing, in a handheld detector as someone enters a facility or fly it on a drone to map an area.”

However, the uses of this technology extend far beyond border security.

“It has the potential to provide us with better data from nuclear physics experiments, enhance national security applications both at home and abroad and has applications in fusion energy,” Carlson said.

Feng and Carlson collaborated to develop the state-of-the-art technology known as Organic Glass Scintillators for radiation detection. Sandia recently licensed the technology to Blueshift Optics, paving the way for potential commercial production.

Stronger, stretchier, self-healing plastic

The complex shape of an origami crane that was restored using heat after being flattened.
Image Credit: ©2023, Shota Ando

An innovative plastic, stronger and stretchier than the current standard type and which can be healed with heat, remembers its shape and partially biodegradable, has been developed by researchers at the University of Tokyo. They created it by adding the molecule polyrotaxane to an epoxy resin vitrimer, a type of plastic. Named VPR, the material can hold its form and has strong internal chemical bonds at low temperatures. However, at temperatures above 150 degrees Celsius, those bonds recombine and the material can be reformed into different shapes. Applying heat and a solvent breaks VPR down into its raw components. Submerging it in seawater for 30 days also resulted in 25% biodegradation, with the polyrotaxane breaking down into a food source for marine life. This new material could have wide-reaching applications for a more circular economy to recirculate resources and reduce waste, from engineering and manufacturing, to medicine and sustainable fashion.

Despite global campaigns to curb plastic use and waste, it is difficult to avoid the ubiquitous material. From toys and clothes, homeware and electronics, to vehicles and infrastructure, nowadays it may seem like it is in almost everything we use. Although useful, there are many issues associated with plastic’s life cycle and disposal. Developing alternatives which last longer, can be reused and recycled more easily, or which are made from environmentally friendly sources, is key to helping solve these problems and realize several of the United Nations’ Sustainable Development Goals.

Carbon copy: new method of recycling carbon fiber shows huge potential

UNSW Canberra researcher Di He with a sample of carbon fiber recycled using a method he developed.
 Photo Credit: UNSW Canberra

Ultra-light cars made from recycled carbon fiber are a step closer, thanks to a new method of recycling developed at UNSW Canberra. 

As manufacturing and technology continually take steps forward, products are using more advanced materials and becoming more sophisticated, but also more complicated.

This presents a problem when these products reach the end of their useable life, because they’re either difficult or expensive to recycle, or both.

For example, as the world transitions to electric vehicles, disposing of their used batteries, some made with highly toxic materials, will be a challenge.

As it stands, many advanced products either end up in landfill or incinerated, which is a waste of valuable resources and harmful to the planet.

One material that has been difficult to recycle is carbon fiber.

Breakthrough synthesis method improves solar cell stability

Jin Hou is a Rice University graduate student and lead author on a study published in Nature Synthesis. Photo Credit: Courtesy of Jin Hou

Solar cell efficiency has soared in recent years due to light-harvesting materials like halide perovskites, but the ability to produce them reliably at scale continues to be a challenge.

A process developed by Rice University chemical and biomolecular engineer Aditya Mohite and collaborators at Northwestern University, the University of Pennsylvania and the University of Rennes yields 2D perovskite-based semiconductor layers of ideal thickness and purity by controlling the temperature and duration of the crystallization process.

Known as kinetically controlled space confinement, the process could help improve the stability and reduce the cost of halide perovskite-based emerging technologies like optoelectronics and photovoltaics.

Directed evolution of catalysts for the energy transition

Alfred Ludwig, professor for Materials Discovery and Interfaces, is involved in the Synergy Grant from Ruhr University Bochum.
Photo Credit: © RUB, Marquard

Catalysts should be efficient and durable. To find them, four teams are systematically working together on new concepts. They are being funded by the European Research Council (ERC) with 10 million euros.

Hydrogen is considered the energy carrier of the future. To produce it, reactions have to be catalyzed, some of which take place under extreme conditions. Previous electrocatalysts usually cannot withstand this for long – new materials are needed that are both powerful and durable, and ideally do not contain expensive and scarce elements. A Danish-German-Swiss research consortium is systematically taking a new approach in the project "Directed Evolution of Metastable Electrocatalyst Interfaces for Energy Conversion", or DEMI for short. DEMI will be funded for the next six years with around 10 million euros as a Synergy Grant from the European Research Council ERC, the highest award for researchers in the EU. 

Preventing collateral damage in cancer treatment

The Electronic Polymer Dosimeter for Radiotherapy, created by a team at Sandia National Laboratories.
 Photo Credit: Spencer Toy

Using a simple concept and a patented Sandia sensor that detects radioactive materials, a team at Sandia National Laboratories has developed a patch to stop damage to healthy tissue during proton radiotherapy, one of the best tools to target certain cancerous tumors.

“This is an important need, especially among pediatric patients,” said Patrick Doty, one of the creators of the patch. Proton radiation therapy is used to send a high dose of radiation into a specific area of the body to disrupt and destroy tumor cells, but the radiation also kills nearby healthy cells. The goal is to be as precise as possible when targeting the radiation, but human movement is an issue especially when dealing with children.

“If you breathe, you move. When your heart beats, you move. You can’t stop those types of motions. And kids are wiggly. You can’t keep them still for long,” Doty said. “Sometimes doctors must resort to general anesthesia and the treatments sometimes go day after day for six weeks. Imagine going to the hospital and having to be put under every day for weeks. That is not good for anyone, but it’s especially bad for kids.”

From a five-layer graphene sandwich, a rare electronic state emerges

When stacked in five layers in a rhombohedral pattern, graphene takes on a rare “multiferroic” state, in which the material’s electrons (illustrated here as spheres) exhibit two preferred electronic states: an unconventional magnetism (represented as orbits around each electron), and “valley,” or a preference for one of two energy states (depicted in red versus blue). The results could help advance more powerful magnetic memory devices.
Illustration Credits: Sampson Wilcox, RLE
(CC BY-NC-ND 3.0 DEED)

Ordinary pencil lead holds extraordinary properties when shaved down to layers as thin as an atom. A single, atom-thin sheet of graphite, known as graphene, is just a tiny fraction of the width of a human hair. Under a microscope, the material resembles a chicken-wire of carbon atoms linked in a hexagonal lattice. 

Despite its waif-like proportions, scientists have found over the years that graphene is exceptionally strong. And when the material is stacked and twisted in specific contortions, it can take on surprising electronic behavior.

Now, MIT physicists have discovered another surprising property in graphene: When stacked in five layers, in a rhombohedral pattern, graphene takes on a very rare, “multiferroic” state, in which the material exhibits both unconventional magnetism and an exotic type of electronic behavior, which the team has coined ferro-valleytricity. 

“Graphene is a fascinating material,” says team leader Long Ju, assistant professor of physics at MIT. “Every layer you add gives you essentially a new material. And now this is the first time we see ferro-valleytricity, and unconventional magnetism, in five layers of graphene. But we don’t see this property in one, two, three, or four layers.”