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nanotimes News in Brief

12-04 :: April/May 2012

Energy Generation // Scientists Generate Electricity from Viruses

S

cientists from the Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a

way to generate power using harmless viruses that convert mechanical energy into electricity.

“More research is needed, but our work is a promi- sing first step toward the development of personal power generators, actuators fors 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 UC Berkeley associate professor of bioengineering.

The Berkeley Lab researchers first had to determine if the M13 virus is piezoelectric. Lee turned to Ramesh, an expert in studying the electrical properties of thin films at the nanoscale. They applied an electrical field to a film of M13 viruses and watched what hap- pened using a special microscope. Helical proteins that coat the viruses twisted and turned in response-a sure sign of the piezoelectric effect at work.

Next, the scientists increased the virus‘s piezoelec- tric strength. They used genetic engineering to add four negatively charged amino acid residues to one end of the helical proteins that coat the virus. These residues increase the charge difference between the proteins‘ positive and negative ends, which boosts the voltage of the virus.

The scientists further enhanced the system by sta- cking films composed of single layers of the virus on top of each other. They found that a stack about 20 layers thick exhibited the strongest piezoelectric effect. The only thing remaining to do was a de- monstration test, so the scientists fabricated a virus- based piezoelectric energy generator. They created the conditions for genetically engineered viruses to spontaneously organize into a multilayered film that measures about one square centimeter. This film was then sandwiched between two gold-plated elec- trodes, which were connected by wires to a liquid- crystal display.

When pressure is applied to the generator, it pro- duces up to six nanoamperes of current and 400 millivolts of potential. That‘s enough current to flash the number “1” on the display, and about a quarter the voltage of a triple A battery.

Byung Yang Lee, Jinxing Zhang, Chris Zueger, Woo-Jae Chung, So Young Yoo, Eddie Wang, Joel Meyer, Rama- moorthy Ramesh & Seung-Wuk Lee: Virus-based piezo- electric energy generation, In: Nature Nanotechnology AOP, May 13, 2012, DOI:10.1038/nnano.2012.69: http://dx.doi.org/10.1038/nnano.2012.69