ELECTRICAL FIELD: A microscopic image of the fibers in a nanogenerator.
Researchers have taken a step toward generating electrical power for small devices without the need for batteries or other power sources. All you would need is motion.
Zhong Lin Wang and a team at the Georgia Institute of Technology developed a system using pairs of zinc oxide nanogenerators that produce current when rubbed against each other. The research is sponsored by the National Science Foundation, Energy Department and the Emory-Georgia Tech Nanotechnology Center for Personalized and Predictive Oncology.
Wang and his team, writing in the journal Nature, said they covered Kevlar micofibers with zinc oxide nanowires, producing what look like tiny bottle brushes. The fibers actually are grown: a seed layer of zinc oxide is applied to the Kevlar, then immersed in a reactive solution for 12 hours, causing the nanowires to grow out from the surface. When in motion, the tips of the brushes rub against one another, generating electrical current using the piezoelectric effect. Walking could produce enough motion to generate electricity, but so could motion generated from wind and vibrations from sound. Wang said a square meter of fabric could potentially generate as much as 80 milliwatts of electricity, which would be enough to power a cell phone or iPod. So, an oversized shirt could do the trick. In addition, the fibers could be used in things such as curtains, tents or flags.
One possible use for the technology would be to allow soldiers in the field to generate enough electricity to power small devices.
One drawback: Zinc oxide is sensitive to moisture, so if nanogenerators were woven into a shirt, you couldn't wash it ' unless the nanowires were somehow insulated against moisture.
That wouldn't be a problem for some people we know, but for the moment, it might stand in the way of mass appeal.
Kevin McCaney is the executive editor of GCN. Follow him on Twitter: @KevinMcCaney.