Piezoelectric materials, which generate an electric current when compressed or stretched, are familiar and widely used: think of lighters that spark when you press a switch, but also microphones, sensors, motors and all kinds of other devices.
Now a group of physicists has found a material with a similar property, but for magnetism. This “piezomagnetic” material changes its magnetic properties when put under mechanical strain.
“Piezomagnetic materials are rarely found in nature, as far as I’m aware,” said Nicholas Curro, professor of physics at UC Davis and senior author of a paper on the discovery published March 13 in the journal Nature Communications.
Curro and colleagues were studying a barium-iron-arsenic compound, BaFe2As2, that can act as a superconductor at temperatures of about 25 Kelvin when doped with small amounts of other elements. This type of iron-based superconductor is interesting because although... more
UCSB researchers find that the chemical topology of silica can influence the effectiveness of many chemical processes that use it
Better known as glass, silica is a versatile material used in myriad industrial processes, from catalysis and filtration, to chromatography and nanofabrication. Yet despite its ubiquity in labs and cleanrooms, surprisingly little is known about silica’s surface interactions with water at a molecular level.
“The way water interacts with a surface affects many processes,” said Songi Han, a UC Santa Barbara professor of chemistry and author on a recent paper in the Proceedings of the National Academy of Sciences. In many cases, she explained, scientists and engineers intuit the potential interactions between silica and water and design equipment, experiments and processes based on empirical... more
Scientists at Rice University and the Indian Institute of Science, Bangalore, have discovered a method to make atomically flat gallium that shows promise for nanoscale electronics.
The Rice lab of materials scientist Pulickel Ajayan and colleagues in India created two-dimensional gallenene, a thin film of conductive material that is to gallium what graphene is to carbon.
Extracted into a two-dimensional form, the novel material appears to have an affinity for binding with semiconductors like silicon and could make an efficient metal contact in two-dimensional electronic devices, the researchers said.
The new material was introduced in Science Advances.
Gallium is a metal with a low melting point; unlike graphene and many other 2-D structures, it cannot yet be grown with vapor phase deposition methods. Moreover, gallium also has a tendency to oxidize quickly. And... more
Lightning and volcanos both produce glass, and humans have been making glass from silicon dioxide since prehistory.
Industrialization brought us boron-based glasses, polymer glasses and metallic glasses, but now an international team of researchers has developed a new family of glass based on metals and organic compounds that stacks up to the original silica in glass-forming ability.
Glass-forming ability is the ability of a liquid to avoid crystallization during cooling.
"Glass is a liquid frozen into a solid-like material in noncrystalline form," said John C. Mauro, professor of materials science and engineering, Penn State. "Mechanically it behaves as a solid but it is somewhere between a liquid and a solid."
The key to making glass is to melt the source materials and then somehow... more
At the scale of microdevices, adhesion is one of the most important forces that engineers need to contend with — Brown University researchers have come up with a new way to measure it.
Brown University engineers have devised a new method of measuring the stickiness of micro-scale surfaces. The technique, described in Proceedings of the Royal Society A, could be useful in designing and building micro-electro-mechanical systems (MEMS), devices with microscopic moving parts.
At the scale of bridges or buildings, the most important force that engineered structures need to deal with is gravity. But at the scale of MEMS — devices like the tiny accelerometers used in smartphones and Fitbits — the relative importance of gravity decreases, and adhesive forces become more important.
“The main thing that matters at the microscale is what sticks to what,” said Haneesh Kesari... more
Researchers in Oregon State University’s College of Engineering have taken a key step toward the rapid manufacture of flexible computer screens and other stretchable electronic devices, including soft robots.
The advance by a team within the college’s Collaborative Robotics and Intelligent Systems Institute paves the way toward the 3D printing of tall, complicated structures with a highly conductive gallium alloy.
Researchers put nickel nanoparticles into the liquid metal, galinstan, to thicken it into a paste with a consistency suitable for additive manufacturing.
“The runny alloy was impossible to layer into tall structures,” said Yiğit Mengüç, assistant professor of mechanical engineering and co-corresponding author on the study. “With the paste-like texture, it can be layered while maintaining its capacity to flow, and to stretch inside of rubber tubes. We demonstrated the potential... more
The concept of friction was already investigated five hundred years ago by Leonardo da Vinci. His most important result, the proportionality of friction to normal force, is still used extensively today.
UvA researchers, in collaboration with colleagues from Germany, have now shown that nevertheless, Da Vinci’s relation does not always accurately describe reality. Their results have been published in Nature Communications this week.
Friction is responsible for about twenty percent of the world energy consumption. The main reason for this is that frictional forces slow down the motion of surfaces in contact: think of the moving parts in a car engine. Over five hundred years ago, Leonardo da Vinci was the first person to study friction systematically. Da Vinci’s main result is still used today by many engineers: friction is proportional to the normal force. That is: when two objects are... more
Engineers at the University of Maryland (UMD) have for the first time demonstrated that wood can be directly converted into a carbon sponge capable of withstanding repeated compression and other extreme mechanical conditions.
The new sponge can be used in various applications such as energy storage (e.g., batteries), pollutant treatment, and electronic devices and sensors.
The UMD engineers’ wood carbon sponge overcomes several limiting factors of other lightweight, compressible carbon sponges because it is simpler, less expensive, and more sustainable to produce. Most lightweight, compressible carbon sponges are made from raw materials that are usually nonrenewable fossil resources—such as graphene—and by a complicated fabrication process that involves multiple steps and environmentally unfriendly chemicals. In contrast, the UMD researchers use a simple chemical process to transform balsa wood, a choice... more
Soft robots that can sense touch, pressure, movement and temperature
Researchers at Harvard University have built soft robots inspired by nature that can crawl, swim, grasp delicate objects and even assist a beating heart, but none of these devices has been able to sense and respond to the world around them.
That’s about to change.
Inspired by our bodies’ sensory capabilities, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering have developed a platform for creating soft robots with embedded sensors that can sense movement, pressure, touch, and even temperature.
The research is published in Advanced Materials.
“Our research represents a foundational... more
Cephalopods—which include octopuses, squid, and cuttlefish—are masters of disguise. They can camouflage to precisely match their surroundings in a matter of seconds, and no scientist has quite been able to replicate the spectacle.
But new research by Leila Deravi, assistant professor of chemistry and chemical biology at Northeastern, brings us a step closer.
The chromatophore organs, which appear as hundreds of multi-colored freckles on the surface of a cephalopod’s body, contribute to fast changes in skin color. In a paper published last week in Advanced Optical Materials, Deravi’s group describes its work in isolating the pigment granules within these organs to better understand their role in color change. The researchers discovered these granules have remarkable optical qualities and used them to make thin films and fibers that could be incorporated into textiles, flexible displays, and future color-changing... more