Materials

Staple-like particles reveal new path to strong materials

alse6588 — Tue, 14 Apr 2026 17:18:17 +0000

Staple-like particles reveal new path to strong materials alse6588 Tue, 04/14/2026 - 11:18

Alexander Servantez

A tightly packed ball of office staples can be surprisingly strong.Try to pull it apart and the tangled metal resists like a solid object.

But with the right movement or vibration, that same bundle can quickly fall back into loose pieces.

A team of engineers and materials scientists in the Paul M. Rady Department of Mechanical Engineering at ��Ƶ are exploring how this uncanny combination of strength and flexibility could inspire a new class of materials built on interlocking particles. By mimicking the way staples lock together and release, the researchers believe these emerging materials can one day form structures that are strong, adaptable and even recyclable.

“We’ve been playing around with the idea of building blocks and geometry for many years, but we started looking at interlocking, entangled particles only recently,” said Professor Francois Barthelat, the leader of the Laboratory for Advanced Materials & Bioinspiration. “We are excited about the combination of properties we can get out of these systems and we believe this technology has the potential to go in many directions.”

Unraveling the research

A bird nest made out of interwoven sticks and fibers.

The work, recently published in the Journal of Applied Physics, focuses on what the researchers call “entanglement”—when multiple particles become intertwined with one another, creating a link.

It’s not a new concept. In fact, nature is filled with examples of objects or materials that tangle and interlock with each other to create strong structures. Think about that giant bird nest on the tree in your neighborhood made out of interwoven sticks and fibers, or the interplay of hard minerals and soft proteins in your bones.

But how can scientists recreate that kind of natural entanglement in manufactured materials? The researchers in Barthelat’s lab say the answer revolves around one key concept: particle shape.

“Let’s take sand as an example. Sand is smooth and convex-shaped, meaning it cannot interlock from grain to grain,” PhD student Youhan Sohn said. “However, we found that if we change the shape of a grain of sand, we can drastically affect its behavior and mechanical properties, including the particle’s ability to link with other particles.”

Once the group came to this realization, they began running Monte Carlo simulations, a type of computational analysis, to predict exactly how the particles interlock with each other. Their goal was to find the optimal geometry that delivered the maximum entanglement.

A video demonstrating a pickup test used to analyze particle entanglement.

After finding the optimal shape, the team performed pickup tests to see how the entangled particles actually behaved.

The tests showed that a “two-legged” particle—similar in shape to a staple—had the greatest potential for entanglement. But the researchers also discovered several unexpected advantages that made the design even more intriguing.

The first was its rare blend of tensile strength and toughness, a combination the researchers say conventional materials rarely achieve simultaneously.

“Our entangled granular material using the staple-like particle demonstrates both high strength and toughness at the same time,” said PhD student Saeed Pezeshki.

Next, was its unique ability to rapidly assemble—and just as quickly come apart.

By applying different vibrational patterns to the material, the team was able to change its level of entanglement on demand. A light vibration, for example, could be used to interlock and strengthen the particles, while a larger vibration could cause them to completely unravel.

“It’s a strange material because it’s obviously not a liquid. However, it’s also not quite solid. This opens new and intriguing engineering possibilities,” Barthelat said. “Handling a bundle of these entangled particles feels very remote and exotic.”

Professor Francois Barthelat at the Triple E Fair showcasing his team's research to help middle school students explore engineering.

PhD student Youhan Sohn guiding middle school students through a series of pickup tests to help them visualize particle entanglement.

PhD student Saeed Pezeshki demonstrating the mechanical behavior of staple-like particles for middle school students.

Reassembling the impact

A close look at a free-standing arch made of crown-leg staples.

One of those possibilities comes in the realm of sustainability. The group believes that one day, large buildings and structures like bridges can be designed using entangled materials, allowing them to be disassembled when no longer needed or even fully recycled.

Or maybe entangled materials can make their way into the world’s next great robotic systems, sort of like the ones you’ve seen in some of your favorite sci-fi movies.

“I was talking with other students who believe this technology can be used in swarm robotics— where small robots can entangle, do a task and then disentangle when they are done,” said Pezeshki.

“Yes, kind of like that liquid metal T-1000 in Terminator 2 who can change shape to slide under a door and then transform back to a human’s size on the other side,” added Barthelat. “It’s expensive and scaling up is a challenge, but it’s something that’s on everybody’s mind.”

A close-up photo showing two spiky burrs in nature.

For now, the group is focused on building out the next phase of their research. They are currently testing a new particle shape with added protruding “legs”—similar to those spiky plant burrs that stick relentlessly to your shoes when you step on them—which they believe can generate even stronger entanglement properties.

But no matter what project they are working on, the team says the most important thing about their work is maintaining the passion and excitement.

“We’re not quite sure where this is going to go, but we’re going to continue the fun,” Barthelat said. “Most people don’t think about making strong materials in this way out of something like staples, because they think it’s counterintuitive. Until they try breaking a bundle of staples in half and see that it’s impossible.

“We love to take a difficult project like this and dig in.”

A tightly packed ball of office staples can be surprisingly strong. Try to pull it apart and the tangled metal resists like a solid object. But with the right movement or vibration, that same bundle can quickly fall back into loose pieces. A team of engineers and materials scientists in the Paul M. Rady Department of Mechanical Engineering at ��Ƶ are exploring how this uncanny combination of strength and flexibility could inspire a new class of materials built on interlocking particles.

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New materials, old physics – the science behind how your winter jacket keeps you warm

Alexander James Servantez — Mon, 05 Jan 2026 20:43:25 +0000

New materials, old physics – the science behind how your winter jacket keeps you warm Alexander Jame… Mon, 01/05/2026 - 13:43

Assistant Professor Longji Cui is a materials expert who develops high precision instrumentation and computational techniques to explore energy transport, conversion, and dissipation at extreme scales. In this article by The Conversation, Cui explains how even something as simple as winter jackets that keep you warm during chilly days are a testament to centuries-old physics and cutting-edge science.

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Bruns researches cybernetic human advancement with New Frontiers Grant

Alexander James Servantez — Fri, 20 Jun 2025 17:51:14 +0000

Bruns researches cybernetic human advancement with New Frontiers Grant Alexander Jame… Fri, 06/20/2025 - 11:51

Associate Professor Carson Bruns has received a $50,000 grant through ��Ƶ's New Frontier Grant Program. The funding will allow Bruns and a couple of key collaborators to develop a new suite of body-integrated technology that can help monitor health, help with mobility challenges and enable peak performance in a range of daily activities.

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Tiny robot team could be a gamechanger for safety inspections

Alexander James Servantez — Wed, 21 May 2025 15:29:25 +0000

Tiny robot team could be a gamechanger for safety inspections Alexander Jame… Wed, 05/21/2025 - 09:29

Alexander Servantez

One slithers. One crawls. Neither looks like much on their own. But together, they form a super team—one that might just change how we inspect the most complicated machines in the world.

Kaushik Jayaram, an assistant professor in the Paul M. Rady Department of Mechanical Engineering at ��Ƶ, is working to build the next generation of robot inspection tools by studying some of nature’s simplest creatures.

This robotic duo is about as odd as it is ingenious: tiny, insect-inspired robots paired with inflatable vine-like robots that grow like plants and curl like snakes. These high-tech helpers can navigate a complex maze of machinery and squeeze through the tightest of spaces—like the guts of a jet engine—to potentially perform non-destructive evaluation faster, cheaper and better than ever before.

The tiny mCLARI robot, developed by Assistant Professor Kaushik Jayaram and his team in the Animal Inspired Movement and Robotics Laboratory.

“If you look at the infrastructure around us, there are a lot of buildings, bridges, dams and machines that have all of these little nooks and crannies,” said Jayaram, who is also affiliated with the BioFrontiers Institute, the Biomedical Engineering Program, the Robotics Program and the Materials Science and Engineering Program. “They need very careful, regular inspection and maintenance, but there’s just no easy, cost-effective way to get in.”

Jayaram said there is also an element of public safety involved. According to the Federal Aviation Administration, nearly 15% of aviation accidents are caused by mechanical malfunction.

In just this year alone, the National Transportation Safety Board has reported 94 aviation accidents, 13 of which have been identified as fatal incidents.

“When it comes to tasks such as flying, where human safety is paramount, we need aircraft technology and machinery to work 100% of the time,” Jayaram said. “Our research is one of the efforts to address these concerns using the advantages of robotics.”

The work, in collaboration with Laura Blumenschein at Purdue University, has drawn interest from the U.S. Air Force Research Laboratory. They’ve awarded the two researchers a three-year, $1.4 million grant to prove these small robots can work together to produce big results.

But as unlikely as this robotic team might seem, Jayaram believes they have the perfect blend of “offense” and “defense” to get these dirty and delicate jobs done.

First on the roster is Jayaram’s mCLARI microrobot. This tiny machine—weighing in at less than a gram—can climb, squeeze through cracks the size of a penny and move with a millimeter precision.

However, due to its small stature, it struggles to carry any extra weight. Large batteries and electronics are incompatible with the little robot, and without them it cannot travel long distances or maneuver tight spaces effectively.

The inflatable vine-like robot, developed by Laura Blumenschein, an assistant professor at Purdue University.

That’s where its vine-like teammate comes in. This robot can inflate like a party favor, allowing it to carry more weight and conform to the environment. In Jayaram’s vision, the inflatable snake can act as mCLARI’s personal Uber driver, negotiating constraints of tight spaces and dropping the tiny robot directly at the site of inspection.

Once in location, Jayaram said the mCLARI robot, fitted with cameras and miniature evaluation sensors, can gather and transmit real-time data for offline analysis. When it’s done, it can hop right back on the snake-like robot and the team can make the winding journey back home, saving hours of evaluation time and thousands of dollars in service costs in the process.

“Each of the robotic systems have their own pros and cons,” said Jayaram. “By combining the strengths of these two robots, we’re overcoming the disadvantages to create a single collaborative system that can give us quick insight into these compact and confined spaces.”

But this tiny squad of robots is capable of much more than just inspection. In fact, Jayaram dreams of a day where his insect and vine-inspired robotic friends can be deployed in a variety of scenarios where being small, agile and adaptive are a premium.

Maybe one day this robotic team can play a vital role in environmental monitoring to detect high-risk wildfire zones and prevent ecological damage. Or maybe they can be used in disaster response situations—like a collapsed building—to help save human lives.

Jayaram said the possibilities are truly endless.

“These small, confined crevices and spaces are actually way more ubiquitous than we originally thought. Even in the medical arena—if we shrink these robots even further, make them shapeshift, and use biocompatible materials, maybe our technology can one day be crawling inside our bodies, detecting and releasing blood clots or taking measurements just like a pill,” Jayaram said. “We get very excited when we think about the future. If we can build systems that can effectively navigate the world and combine them with sensors, we can do a lot.”

Assistant Professor Kaushik Jayaram, in collaboration with Laura Blumenschein, has received a $1.4 million grant from the U.S. Air Force Research Laboratory to develop a tiny robot super team capable of navigating a complex maze of machinery and squeeze through the tightest of spaces—like the guts of a jet engine—to potentially perform non-destructive evaluation faster, cheaper and better than ever before.

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New discovery shows how molecules can mute heat like music

Alexander James Servantez — Wed, 07 May 2025 03:00:00 +0000

New discovery shows how molecules can mute heat like music Alexander Jame… Tue, 05/06/2025 - 21:00

Alexander Servantez

Imagine you are playing the guitar—each pluck of a string creates a sound wave that vibrates and interacts with other waves.

Now shrink that idea down to a small single molecule, and instead of sound waves, picture vibrations that carry heat.

Ultra-high vacuum scanning probe setup modified by the Cui Research Group to conduct thermal microscopy experiments.

A team of engineers and materials scientists in the Paul M. Rady Department of Mechanical Engineering at ��Ƶ has recently discovered that these tiny thermal vibrations, otherwise known as phonons, can interfere with each other just like musical notes—either amplifying or canceling each other, depending on how a molecule is "strung" together.

Phonon interference is something that’s never been measured or observed at room temperature on a molecular scale. But this group has developed a new technique that has the power to display these tiny, vibrational secrets.

The breakthrough study was led by Assistant Professor Longji Cui and his team in the Cui Research Group. Their work, funded by the National Science Foundation in collaboration with researchers from Spain (Instituto de Ciencia de Materiales de Madrid, Universidad Autónoma de Madrid), Italy (Istituto di Chimica dei Composti Organometallici) and the ��Ƶ Department of Chemistry, was recently published in the journal Nature Materials.

The group says their findings will help researchers around the world gain a better understanding of the physical behaviors of phonons, the dominant energy carriers in all insulating materials. They believe one day, this discovery can revolutionize how heat dissipation is managed in future electronics and materials.

“Interference is a fundamental phenomenon,” said Cui, who is also affiliated with the Materials Science and Engineering Program and the Center for Experiments on Quantum Materials. “If you have the capability to understand interference of heat flow at the smallest level, you can create devices that have never been possible before.”

The world’s strongest set of ears

Cui says molecular phononics, or the study of phonons in a molecule, has been around for quite some time as a primarily theoretical discussion. But you need some pretty strong ears to “listen” to these molecular melodies and vibrations first-hand, and that technology just simply hasn’t existed.

A sneak peek into the ultra-high vacuum scanning probe microscopy setup used to conduct molecular measurements.

That is, until Cui and his team stepped in.

The group designed a thermal sensor smaller than a grain of sand or even a sawdust particle. This little probe is special: it features a record-breaking resolution that allows them to grab a molecule and measure phonon vibration at the smallest level possible.

Using these specially designed miniature thermal sensors, the team studied heat flow through single molecular junctions and found that certain molecular pathways can cause destructive interference—the clashing of phonon vibrations to reduce heat flow.

Sai Yelishala, a PhD student in Cui’s lab and lead author of the study, said this research using their novel scanning thermal probe represents the first observation of destructive phonon interference at room temperature.

In other words, the team has unlocked the ability to manage heat flow at the scale where all materials are born: a molecule.

“Let’s say you have two waves of water in the ocean that are moving towards each other. The waves will eventually crash into each other and create a disturbance in between,” Yelishala said. “That is called destructive interference and that is what we observed in this experiment. Understanding this phenomenon can help us suppress the transport of heat and enhance the performance of materials on an extremely small and unprecedented scale.”

Tiny molecules, vast potential

Developing the world’s strongest set of ears to measure and document never-before-seen phonon behavior is one thing. But just what exactly are these tiny vibrations capable of?

PhD student and lead author of the study Sai Yelishala (right), along with Postdoctoral Associate and second author Yunxuan Zhu (left). Both are members of the Cui Research Group led by Assistant Professor Longji Cui.

“This is only the beginning for molecular phononics,” said Yelishala. “New-age materials and electronics have a long list of concerns when it comes to heat dissipation. Our research will help us study the chemistry, physical behavior and heat management in molecules so that we can address these concerns.”

Take an organic material, like a polymer, as an example. Its low thermal conductivity and susceptibility to temperature changes often poses great risks, such as overheating and degradation.

Maybe one day, with the help of phonon interference research, scientists and engineers can develop a new molecular design. One that turns a polymer into a metal-like material that can harness constructive phonon vibrations to enhance thermal transport.

The technique can even play a large role in areas like thermoelectricity, otherwise known as the use of heat to generate electricity. Reducing heat flow and suppressing thermal transport in this discipline can enhance the efficiency of thermoelectric devices and pave the way for clean energy usage.

The group says this study is just the tip of the iceberg for them, too. Their next projects and collaborations with ��Ƶ chemists will expand on this phenomenon and use this novel technique to explore other phononic characteristics on a molecular scale.

“Phonons travel virtually in all materials,” Yelishala said. “Therefore we can guide advancements in any natural and artificially made materials at the smallest possible level using our ultra-sensitive probes.”

Assistant Professor Longji Cui and his team in the Cui Research Group have developed a new technique that allows them to measure phonon interference inside of a tiny molecule. They believe one day, this discovery can revolutionize how heat dissipation is managed in future electronics and materials.

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An artistic rendering showing thermal phonon interference in a molecule, otherwise known as "a molecular song."

New technology turns waste heat into electricity, defies physical limit

Alexander James Servantez — Mon, 17 Feb 2025 16:15:05 +0000

New technology turns waste heat into electricity, defies physical limit Alexander Jame… Mon, 02/17/2025 - 09:15

Alexander Servantez

A team of engineers and material scientists in the Paul M. Rady Department of Mechanical Engineering at ��Ƶ has developed a new technology to turn thermal radiation into electricity in a way that literally teases the basic law of thermal physics.

The breakthrough was discovered by the Cui Research Group, led by Assistant Professor Longji Cui. Their work, in collaboration with researchers from the National Renewable Energy Laboratory (NREL) and the University of Wisconsin-Madison, was recently published in the journal Energy & Environmental Sciences.

The group says their research has the potential to revolutionize manufacturing industries by increasing power generation without the need for high temperature heat sources or expensive materials. They can store clean energy, lower carbon emissions and harvest heat from geothermal, nuclear and solar radiation plants across the globe.

In other words, Cui and his team have solved an age-old puzzle: how to do more with less.

“Heat is a renewable energy source that is often overlooked,” Cui said. “Two-thirds of all energy that we use is turned into heat. Think of energy storage and electricity generation that doesn’t involve fossil fuels. We can recover some of this wasted thermal energy and use it to make clean electricity.”

Breaking the physical limit in vacuum

High-temperature industrial processes and renewable energy harvesting techniques often utilize a thermal energy conversion method called thermophotovoltaics (TPV). This method harnesses thermal energy from high temperature heat sources to generate electricity.

But existing TPV devices have one constraint: Planck’s thermal radiation law.

PhD student Mohammad Habibi showcasing one of the group's TPV cells used for power generation. Habibi was the leader of both the theory and experimentation of this groundbreaking research.

“Planck’s law, one of most fundamental laws in thermal physics, puts a limit on the available thermal energy that can be harnessed from a high temperature source at any given temperature,” said Cui, also a faculty member affiliated with the Materials Science and Engineering Program and the Center for Experiments on Quantum Materials. “Researchers have tried to work closer or overcome this limit using many ideas, but current methods are overly complicated to manufacture the device, costly and unscalable.”

That’s where Cui’s group comes in. By designing a unique and compact TPV device that can fit in a human hand, the team was able to overcome the vacuum limit defined by Planck’s law and double the yielded power density previously achieved by conventional TPV designs.

“When we were exploring this technology, we had theoretically predicted a high level of enhancement. But we weren’t sure what it would look like in a real world experiment,” said Mohammad Habibi, a PhD student in Cui’s lab and leader of both the theory and experiment of this research. “After performing the experiment and processing the data, we saw the enhancement ourselves and knew it was something great.”

The zero-vacuum gap solution using glass

The research emerged, in part, from the group’s desire to challenge the limits. But in order to succeed, they had to modify existing TPV designs and take a different approach.

“There are two major performance metrics when it comes to TPV devices: efficiency and power density,” said Cui. “Most people have focused on efficiency. However, our goal was to increase power.”

The zero-vacuum gap TPV device, designed by the Cui Research Group.

To do so, the team implemented what’s called a “zero-vacuum gap” solution into the design of their TPV device. Unlike other TPV models that feature a vacuum or gas-filled gap between the thermal source and the solar cell, their design features an insulated, high index and infrared-transparent spacer made out of just glass.

This creates a high power density channel that allows thermal heat waves to travel through the device without losing strength, drastically improving power generation. The material is also very cheap, one of the device’s central calling cards.

“Previously, when people wanted to enhance the power density, they would have to increase temperature. Let’s say an increase from 1,500 C to 2,000 C. Sometimes even higher, which eventually becomes not tolerable and unsafe for the whole energy system,” Cui explained. “Now we can work in lower temperatures that are compatible with most industrial processes, all while still generating similar electrical power than before. Our device operates at 1,000 C and yields power equivalent to 1,400 C in existing gap-integrated TPV devices.”

The group also says their glass design is just the tip of the iceberg. Other materials could help the device produce even more power.

“This is the first demonstration of this new TPV concept,” explained Habibi. “But if we used another cheap material with the same properties, like amorphous silicon, there is a potential for an even higher, nearly 20 times more increase in power density. That’s what we are looking to explore next.”

The broader commercial impact

Assistant Professor Longji Cui (middle) and the Cui Research Group.

Cui says their novel TPV devices would make its largest impact by enabling portable power generators and decarbonizing heavy emissions industries. Once optimized, they have the power to transform high-temperature industrial processes, such as the production of glass, steel and cement with cheaper and cleaner electricity.

“Our device uses commercial technology that already exists. It can scale up naturally to be implemented in these industries,” said Cui. “We can recover wasted heat and can provide the energy storage they need with this device at a low working temperature.

“We have a patent pending based on this technology and it is very exciting to push this renewable innovation forward within the field of power generation and heat recovery.”

Assistant Professor Longji Cui and his team in the Cui Research Group have developed a new technology to turn thermal radiation into electricity in a way that literally teases the basic law of thermal physics. The group says their research has the potential to revolutionize manufacturing industries by increasing power generation without the need for high temperature heat sources or expensive materials.

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Pioneering sodium-ion batteries: a sustainable energy alternative

Alexander James Servantez — Fri, 13 Dec 2024 23:16:06 +0000

Pioneering sodium-ion batteries: a sustainable energy alternative Alexander Jame… Fri, 12/13/2024 - 16:16

Associate Professor Chunmei Ban and her research team are exploring the use of sodium-ion batteries as an alternative to lithium-based energy storage. Sodium is widely distributed in the Earth's crust and is an appealing candidate to remedy concerns over resource scarcity with lithium-ion batteries.

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PhD students earn top National Science Foundation fellowships

Anonymous — Wed, 24 Apr 2024 22:51:12 +0000

PhD students earn top National Science Foundation fellowships Anonymous (not verified) Wed, 04/24/2024 - 16:51

Jeff Zehnder

The National Science Foundation has bestowed three prestigious Graduate Research Fellowship Program awards to University of Colorado Boulder mechanical engineering graduate students.

The national awards recognize and support outstanding grad students from across the country in science, technology, engineering and mathematics (STEM) fields who are pursuing research-based master’s and doctoral degrees.

PhD students Reegan Ketzenberger, Caleb Song, and Jennifer Wu are each receiving the honor for 2024. Find out more about their research below.

Awardees receive a $37,000 annual stipend and cost of education allowance for the next three years as well as professional development opportunities.

Two mechanical engineering PhD students, Alex Hedrick and Carly Rowe, also received honorable mentions from the National Science Foundation program.

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Undergraduate participates in summer water reclamation research

Anonymous — Wed, 25 Aug 2021 18:21:29 +0000

Undergraduate participates in summer water reclamation research Anonymous (not verified) Wed, 08/25/2021 - 12:21

The work is based in Research Professor John Pellegrino’s Fundamental Membrane Development, Characterization, & Applications lab.

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'Electronic skin' promises cheap and recyclable alternative to wearable devices

Anonymous — Fri, 06 Nov 2020 20:51:03 +0000

'Electronic skin' promises cheap and recyclable alternative to wearable devices Anonymous (not verified) Fri, 11/06/2020 - 13:51

Researchers at the University of Colorado Boulder are developing a wearable electronic device that’s “really wearable”—a stretchy and fully-recyclable circuit board that’s inspired by, and sticks onto, human skin.

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Materials

Staple-like particles reveal new path to strong materials

Unraveling the research

Reassembling the impact

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New materials, old physics – the science behind how your winter jacket keeps you warm

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Bruns researches cybernetic human advancement with New Frontiers Grant

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Tiny robot team could be a gamechanger for safety inspections

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New discovery shows how molecules can mute heat like music

The world’s strongest set of ears

Tiny molecules, vast potential

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​New technology turns waste heat into electricity, defies physical limit

Breaking the physical limit in vacuum

The zero-vacuum gap solution using glass

The broader commercial impact

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Pioneering sodium-ion batteries: a sustainable energy alternative

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PhD students earn top National Science Foundation fellowships

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Undergraduate participates in summer water reclamation research

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'Electronic skin' promises cheap and recyclable alternative to wearable devices

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New technology turns waste heat into electricity, defies physical limit