New nanogenerator could charge iPods and cell phones with a wave of the hand

March 31, 2009 The human body is a veritable powerhouse. Every minute of everyday it generates energy, but unfortunately much of this energy is wasted on mundane tasks like burning calories or keeping internal organs running. What if this energy could be harnessed to do something really useful – like charge your iPod or mobile phone? Technology that does just that - converting mechanical energy from body movements or even the flow of blood in the body into electric energy that can be used to power a broad range of electronic devices without using batteries – has been described by scientists from the Georgia Institute of Technology.

Scientists have long been working at ways to better harness kinetic energy with Seiko’s Kinetic Drive wristwatch and the nPower PEG some recent fruits of such labor. Now this technological pathway could be taken to the next level with devices that use simple body movements, the beating of the heart or movement of the wind and convert the low-frequency vibrations generated into electricity by using zinc oxide (ZnO) nanowires. The ZnO nanowires are able to produce electricity as they are piezoelectric - they generate an electric current when subjected to mechanical stress. The diameter and length of the wire are 1/5,000th and 1/25th the diameter of a human hair, which means they can be placed just about anywhere. Another advantage of the technology is that the nanowires can be grown easily on a wide variety of surfaces such as metals, ceramics, polymers, clothing and even tents. Plus the nanogenerators will operate in the air or in liquids once properly packaged.

"This research will have a major impact on defense technology, environmental monitoring, biomedical sciences and even personal electronics," says lead researcher Zhong Lin Wang. The new "nanogenerator" could have countless applications, among them a way to run electronic devices used by the military when troops are far in the field. "Quite simply, this technology can be used to generate energy under any circumstances as long as there is movement," according to Wang. He says there is a growing need by the military and defense agencies for nanoscale sensing devices used to detect bioterror agents. The nanogenerator would be particularly critical to troops in the field, where they are far from energy sources and need to use sensors or communication devices. In addition, having a sensor, which doesn’t need batteries, could be extremely useful to the military and police sampling air for potential bioterrorism attacks in the United States, Wang says. While biosensors have been miniaturized and can be implanted under the skin, he points out that these devices still require batteries, and the new nanogenerator would offer much more flexibility.

A major advantage of this new technology is that many nanogenerators can produce electricity continuously and simultaneously. Add to that the potential to reduce the billions of batteries that make their way into landfill annually and the technology sells itself. On the downside, the greatest challenge in developing these nanogenerators is to improve the output voltage and power.

The research by the team from the School of Material Science and Engineering at the Georgia Institute of Technology was presented at the American Chemical Society's 237th National Meeting in Salt Lake City.

Darren Quick