Tiny wires power nano revolution

A scientist has developed a nanogenerator that can produce a continuous flow of electricity from ultrasonic waves or even blood flow.

Georgia Tech researchers used zinc-oxide nanowires to create this prototype direct-current nanogenerator. (Credit: Gary Meek/Georgia Tech)

Professor Zhong Lin Wang of the Georgia Institute of Technology in the US developed the tiny generator to harvest mechanical energy from its surroundings.

“This is a major step toward a portable, adaptable and cost-effective technology for powering nanoscale devices,” said Zhong Lin Wang, Regents’ Professor in the School of Materials Science and Engineering. “There has been a lot of interest in making nanodevices, but we have tended not to think about how to power them. Our nanogenerator allows us to harvest or recycle energy from many sources to power these devices.”

The prototype is made up of wires that are free to flex just slightly. The nanogenerator takes advantage of the unique coupled piezoelectric and semiconducting properties of zinc oxide nanostructures, which produce small electrical charges when they are flexed. By capturing the output of large numbers of nanowires in motion, the nanogenerator produces a miniscule direct current output.

Wang and his group members expect that their nanogenerator could produce as much as 4 watts per cubic centimeter - based on a calculation for a single nanowire. That would be enough to power a broad range of nanometer-scale defense, environmental and biomedical applications, including biosensors implanted in the body, environmental monitors - and even nanoscale robots.
However, before they can do that, the team needs to optimise the development process.

“We need to be able to better control the growth, density and uniformity of the wires,” Wang said. “We believe we can make as many as millions or even billions of nanowires produce current simultaneously. That will allow us to optimize operation of the nanogenerator.”