Department of Applied Physics and Materials Science - Materials Science

News & Events


Professor Gao Unveils Sensor that Rapidly Detects COVID-19 Infection Status, Severity, and Immunity


One feature of the COVID-19 virus that makes it so difficult to contain is that it can be easily spread to others by a person who has yet to show any signs of infection. Wei Gao, Assistant Professor of Medical Engineering, has developed a new type of multiplexed test (a test that combines multiple kinds of data) with a low-cost sensor that may enable the at-home diagnosis of a COVID infection through rapid analysis of small volumes of saliva or blood, without the involvement of a medical professional, in less than 10 minutes. "This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor," Gao says. "In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity, and severity." [Caltech story]

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Effective Pathway to Convert Greenhouse Gas into Valuable Products


A research team from Caltech and the UCLA Samueli School of Engineering has demonstrated a promising way to efficiently convert carbon dioxide into ethylene—an important chemical used to produce plastics, solvents, cosmetics, and other important products globally. They developed nanoscale copper wires with specially shaped surfaces to catalyze a chemical reaction that reduces greenhouse gas emissions while simultaneously generating ethylene. "The idea of using copper to catalyze this reaction has been around for a long time, but the key is to accelerate the rate so it is fast enough for industrial production," says William A. Goddard III, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics. [Caltech story]

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Advancing Future Quantum Science Efforts


Five new Department of Energy centers will apply quantum information science to emerging technologies. The centers will develop cutting-edge quantum technologies for use in a wide range of possible applications including scientific computing; fundamental physics and chemistry research; and the design of solar cells and of new materials and pharmaceuticals. Caltech faculty will participate in four of the new science centers: the Quantum Systems Accelerator, led by the Lawrence Berkeley National Laboratory, also known as Berkeley Lab; the Quantum Science Center, led by Oak Ridge National Laboratory; Q-NEXT, led by Argonne National Laboratory; and the Co-design Center for Quantum Advantage, led by Brookhaven National Laboratory. [Caltech story]

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Collecting Hot Carriers: New Process Harvests Excited Quasiparticles


Harry Atwater, Howard Hughes Professor of Applied Physics and Materials Science; Director, Joint Center for Artificial Photosynthesis, has developed a way to eke more energy out of solar power by collecting freshly charged particles before they have an opportunity to cool off. This fundamental research could one day help scientists harvest energy from the sun more efficiently than by the natural photosynthesis used by plants. "If hot carriers, transporting more energy, could be captured, we would be able to wring three to four times as much energy from solar power," says Atwater. [Caltech story]

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A Pathway to Longer-Lasting Lithium Batteries


The energy density of batteries have been a major challenge for consumer electronics, electric vehicles, and renewable energy sources. Julia R. Greer, Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering; Fletcher Jones Foundation Director of the Kavli Nanoscience Institute, has made a discovery that could lead to lithium-ion batteries that are both safer and more powerful. Findings provide guidance for how lithium-ion batteries, one of the most common kinds of rechargeable batteries, can safely hold up to 50 percent more energy. "Every power-requiring application would benefit from batteries with lithium instead of graphite anodes because they can power so much more," says Greer. "Lithium is lightweight, it doesn't occupy much space, and it's tremendously energy dense." [Caltech story]

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Superconducting Twisted Bilayer Graphene—Magic not Needed?


A new study shows that superconductivity in twisted bilayer graphene can exist away from the magic angle when coupled to a two-dimensional semiconductor. "Our observations were quite unexpected. It implies that we only scratched the surface of graphene twistronics. These are exciting times for the field," says Stevan Nadj-Perge, Assistant Professor of Applied Physics and Materials Science. [Caltech story]

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Optical Microcomb Device May Result in Improved Telecommunications, Sensors, Clocks


Modern telecommunications often makes use of multiple lasers of different colors to transmit data, but a new device the size of a cigarette pack can replace them. A team of researchers from Caltech, UC Santa Barbara, and the Swiss Federal Institute of Technology Lausanne (EPFL) have developed a new device that will lead to improved optical data transmission and could have applications ranging from communications to the miniaturization of time standards or to the search for exoplanets. Their device converts laser light of a single frequency into an evenly spaced set of many distinct frequencies (a comb of frequencies). The resulting optical frequency microcomb is built from a single piece of silicon, in much the same way as computer chips. And its many colors can replace many separate lasers for data transmission. "The new approach makes the process as easy as switching on a room light," says co-author Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics and executive officer for Applied Physics and Materials Science. [Caltech story]

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Electronic Skin Fully Powered by Sweat Can Monitor Health


One of the ways we experience the world around us is through our skin. From sensing temperature and pressure to pleasure or pain, the many nerve endings in our skin tell us a great deal. Our skin can also tell the outside world a great deal about us as well. Wei Gao, Assistant Professor of Medical Engineering has developed an electronic skin, or e-skin, that is applied directly on top of your real skin. "We want this system to be a platform," he says. "In addition to being a wearable biosensor, this can be a human–machine interface. The vital signs and molecular information collected using this platform could be used to design and optimize next-generation prosthetics." [Caltech story]

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New Superconducting Film Resists a Magnet's Power to Thwart It


To Joseph Falson, Assistant Professor of Materials Science, electrons are like exotic supercars and his lab wants to build the racetrack. In Falson's analogy, he likens that to driving the supercar down a cobblestone street that limits its speed. "Our job is not to make the supercar, it's just to make the highway," he says. The problem for those who seek to study superconductivity and eventually make practical use of it is that, so far, it has been realized only at ultracold temperatures no warmer than -70 degrees Celsius. "There is a very strong push to realize room-temperature superconductivity—it is one of the holy grails of science," Falson says, "because then you are going to employ these materials in motors or transmission lines, and the loss would be significantly less. It would revolutionize society." [Caltech story]

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Tiny Optical Cavity Could Make Quantum Networks Possible


Andrei Faraon, Professor of Applied Physics and Electrical Engineering, and team have shown that atoms in optical cavities—tiny boxes for light—could be foundational to the creation of a quantum internet. They identified a rare-earth ytterbium ion in the center of a beam. The ytterbium ions are able to store information in their spin for 30 milliseconds. In this time, light could transmit information to travel across the continental United States. "It's a rare-earth ion that absorbs and emits photons in exactly the way we'd need to create a quantum network," says Faraon. "This could form the backbone technology for the quantum internet." [Caltech story]

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