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Light causes crystal lattice to swell, opening new possibilities for artificial muscles, tiny electronics. Credit: Richard Remsing, Ph.D., Temple University.

Researchers are turning to light to rapidly expand nanosheets that can be used to improve artificial muscle and small electronics.

A team from the University of Buffalo has found that tiny crystal lattices called “self-assembling molecular nanosheets” expand after exposed to light, a discovery that could lead to new light-powered actuators, oscillators and other microscopic electronic components used in artificial muscles and other soft robotic systems.

To make the discovery, the researchers tapped into a concept called photostriction—where light is converted into mechanical motion.

“We're using light—anything from sunlight to a simple laser—to cause the two-dimensional nanosheet to expand at an incredibly fast rate,” the study's co-lead author Shenqiang Ren, a researcher at the University at Buffalo's RENEW Institute, said in a statement.

According to Ren, the nanosheet’s expansion— which is aided by the photostrictive effect needed to bypass the electricity required to move— takes place in less than a millisecond. 

The nanosheets, which are made of the molecular charge-transfer compound DBTTF and buckyball molecules, can expand up to 5.7 percent of its original size.

Photostrictive compounds are used for device materials because of their fundamental photophysical properties and light-induced strain applications.

While, molecular charge-transfer crystals exhibiting light–matter interactions have been successfully deployed in optoelectronics, an air-stable molecular material that couples photons and electrons, achieving photostriction through the coupling of light and mechanical degrees of freedom, has not previously been discovered.

The researchers found a substantial light-induced dilation in a molecular material at room temperature, accompanied by simultaneous photocurrent generation.

The study was published in the Proceedings of the National Academy of Sciences of the United States of America.

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