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Berkeley Lab taps piezoelectric properties of biological material

Researchers at the United States Department of Energy's Lawrence Berkeley National Laboratory are harnessing the piezoelectric ability of harmless viruses to convert mechanical energy into electricity.

To demonstrate their findings, the scientists developed a generator that produces enough current to operate a small liquid-crystal display when a finger taps on a postage stamp-sized electrode coated with the specially engineered viruses.

The scientists believe that their findings could eventually lead to tiny devices that could harvest and produce energy from the vibrations of everyday tasks such as shutting a door or climbing stairs.

"More research is needed, but our work is a promising first step toward the development of personal power generators, actuators for use in nano-devices, and other devices based on viral electronics," says Seung-Wuk Lee, a faculty scientist in Berkeley Lab's Physical Biosciences Division and a University of California, Berkeley associate professor of bioengineering.

This is said to be the first device to produce electricity by harnessing the piezoelectric properties of a biological material. Most existing piezoelectric devices are toxic and difficult to work with, limiting the widespread use of the technology.

The scientists worked with thin films of the piezoelectric virus M13 bacteriophage. They increased its piezoelectric ability through genetic engineering, adding four negatively charged amino residues to one end of the proteins that coat the virus. The residues increased the charge difference between the proteins' positive and negative energy, boosting the voltage of the virus.

The scientists further enhanced the system by stacking the virus films on top of each other. A stack 20 layers thick was found to have the strongest piezoelectric effect.

The multilayered film was then sandwiched between two-gold plated electrodes and connected by wires to the liquid-crystal display. When pressure is applied, about six nanoamperes of current and 400 millivolts of potential is generated, about a quarter of the voltage of a triple A battery.

"We're now working on ways to improve on this proof-of-principle demonstration," says Mr. Lee. "Because the tools of biotechnology enable large-scale production of genetically modified viruses, piezoelectric materials based on viruses could offer a simple route to novel microelectronics in the future." – EcoSeed Staff

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