Department of Applied Physics and Materials Science - Materials Science

News & Events


Microstructures Self-Assemble into New Materials


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


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]

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Ultrasound Can Selectively Kill Cancer Cells


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]

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Researchers Develop New Quantum Algorithm


Austin Minnich, Professor of Mechanical Engineering and Applied Physics, Fernando Brandão, Bren Professor of Theoretical Physics, and Garnet Chan, Bren Professor of Chemistry, have developed an algorithm for quantum computers that will help them find use in simulations in the physical sciences. The new algorithm allows a user to find the lowest energy of a given molecule or material. Many people are interested in how to simulate the ground states of molecules and materials. "If we want to do a simulation of water, we could look at how water behaves after it has been blasted into a plasma—an electrically charged gas—but that's not the state water is usually found in; it is not the ground state of water. Ground states are of special interest in understanding the world under ordinary conditions," says Chan. [Caltech story]

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How Electrons Break the Speed Limit


Marco Bernardi, Assistant Professor of Applied Physics and Materials Science, and Jinjian Zhou, Postdoctoral Scholar, have developed a way to predict how electrons interacting strongly with atomic motions will flow through a complex material. "Using a new method, we have been able to predict both the formation and the dynamics of polarons in strontium titanate. This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects," says Bernardi. [Caltech story]

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Caltech Announces the Schmidt Academy for Software Engineering


Caltech has launched the Schmidt Academy for Software Engineering to train the next generation of science-savvy software engineers and set new standards in scientific software. "This is a recognition that computing, software, and machine learning are going to play a very big role in science. Because Caltech is small and collaborative, we have the opportunity to really make a push in that direction," says Kaushik Bhattacharya, the Howell N. Tyson, Sr., Professor of Mechanics and Materials Science and vice provost. [Caltech release]

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New Metamaterial Changes Shape in a Tunable Fashion


Julia R. Greer, Ruben F. and Donna Mettler Professor of Materials Science, Mechanics and Medical Engineering, has developed a new type of architected metamaterial that has the ability to change shape in a tunable fashion. The material has potential applications in next-generation energy storage and bio-implantable micro-devices. [Caltech story]

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Finding the Magic in the Magic Angle


Stevan Nadj-Perge, Assistant Professor of Applied Physics and Materials Science, and colleagues have built upon, the discovery of the "magic angle" for stacked sheets of graphene, by generating an image of the atomic structure and electronic properties of magic angle-twisted graphene, yielding new insight into the phenomenon by offering a more direct way of studying it. They have developed a new method of creating samples of magic angle-twisted graphene that can be used to align the two sheets of graphene very precisely while leaving it exposed for direct observation. [Caltech story]

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Levitating Objects with Light


Ognjen Ilic, postdoctoral scholar in Professor Harry Atwater’s laboratory, and colleagues have designed a way to levitate and propel objects using only light, by creating specific nanoscale patterning on the objects' surfaces. "We have come up with a method that could levitate macroscopic objects," says Professor Atwater, who is also the director of the Joint Center for Artificial Photosynthesis. "There is an audaciously interesting application to use this technique as a means for propulsion of a new generation of spacecraft. We're a long way from actually doing that, but we are in the process of testing out the principles." [Caltech story]

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New Materials Exhibit Split Personality


Julia Greer, Professor of Materials Science, Mechanics and Medical Engineering, and colleagues have determined that the failure of architected materials—the point at which they break when compressed or stretched—can be described using classical continuum mechanics, which models the behavior of a material as a continuous mass rather than as individual (or "discrete") particles. This finding implies a duality to the nature of these materials—in that they can be thought of both as individual particles and also as a single collective. [Caltech story]

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