Department of Applied Physics and Materials Science - Materials Science

News & Events

Highlights

A Pathway to Longer-Lasting Lithium Batteries

08-06-20

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]

Tags: APhMS research highlights MCE Julia Greer KNI

Superconducting Twisted Bilayer Graphene—Magic not Needed?

07-16-20

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]

Tags: APhMS research highlights KNI Stevan Nadj-Perge

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

06-19-20

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]

Tags: APhMS research highlights Kerry Vahala KNI

Electronic Skin Fully Powered by Sweat Can Monitor Health

04-23-20

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]

Tags: APhMS research highlights MedE KNI Wei Gao

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

04-02-20

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]

Tags: APhMS research highlights KNI Joseph Falson

Tiny Optical Cavity Could Make Quantum Networks Possible

03-31-20

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]

Tags: APhMS EE research highlights KNI Andrei Faraon Andrei Ruskuc Jake Rochman John Bartholomew Yan Qi Huan

New Chip-Based Laser Gyroscope Measures Earth's Rotation

03-05-20

Optical gyroscopes are used in applications such as aircraft navigation systems, while MEMS gyroscopes are found in devices like smart phones. Kerry J. Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics; Executive Officer for Applied Physics and Materials Science, has developed an optical gyroscope that combines some of the best characteristics of each into one device. "For more than 20 years, researchers have speculated about placing optical gyroscopes onto a chip very much like the highly successful MEMS gyroscopes. But until recently, there have been very few compelling experiments," Vahala says. [Caltech story]

Tags: APhMS research highlights Kerry Vahala IST

Microstructures Self-Assemble into New Materials

03-03-20

A new process developed at Caltech makes it possible for the first time to manufacture large quantities of materials whose structure is designed at a nanometer scale—the size of DNA's double helix. Pioneered by 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, "nanoarchitected materials" exhibit unusual, often surprising properties—for example, exceptionally lightweight ceramics that spring back to their original shape, like a sponge, after being compressed. Now, a team of engineers at Caltech and ETH Zurich have developed a material that is designed at the nanoscale but assembles itself—with no need for the precision laser assembly. "We couldn't 3-D print this much nanoarchitected material even in a month; instead we're able to grow it in a matter of hours," says Carlos M. Portela, Postdoctoral Scholar. "It is exciting to see our computationally designed optimal nanoscale architectures being realized experimentally in the lab," says Dennis M. Kochmann, Visiting Associate. [Caltech story]

Tags: APhMS research highlights GALCIT MedE MCE Julia Greer KNI Dennis Kochmann postdocs Carlos Portela

Sweat Sensor Detects Stress Levels; May Find Use in Space Exploration

02-27-20

Wei Gao, Assistant Professor of Medical Engineering, has produced a wireless sweat sensor that can accurately detect levels of cortisol, a natural compound that is commonly thought of as the body's stress hormone. This could allow for more widespread and easier monitoring of stress, anxiety, post-traumatic stress disorder, and depression. "We aim to develop a wearable system that can collect multimodal data, including both vital sign and molecular biomarker information, to obtain the accurate classification for deep space stress and anxiety," Gao says. [Caltech story]

Tags: APhMS research highlights MedE KNI Wei Gao

Ultrasound Can Selectively Kill Cancer Cells

02-05-20

Michael Ortiz, Frank and Ora Lee Marble Professor of Aeronautics and Mechanical Engineering, Emeritus, and Morteza Gharib, Hans W. Liepmann Professor of Aeronautics and Bioinspired Engineering; Booth-Kresa Leadership Chair, Center for Autonomous Systems and Technologies; Director, Graduate Aerospace Laboratories; Director, Center for Autonomous Systems and Technologies, are exploring a new technique that could offer a targeted approach to fighting cancer. Low-intensity pulses of ultrasound have been shown to selectively kill cancer cells while leaving normal cells unharmed. In the past, ultrasound waves have been used as a cancer treatment with high-intensity bursts resulting in killing cancer and normal cells. [Caltech story]

Tags: APhMS research highlights GALCIT MedE MCE Morteza Gharib Michael Ortiz