Tiny Electrical Generators Take a Giant Step Forward
Views of the first practical nanogenerator on several scales.
CREDIT: Zhong Lin Wang
Tiny devices that turn bodily movements — such as the snap of one's fingers — into electricity for a cellphone or MP3 player are now much closer to making the leap from the laboratory into everyday life.
Called nanogenerators, these devices are made of so-called piezoelectric materials that generate a current of electricity when stretched or strained. So far, however, nanogenerators have not been able to crank out enough power to be useful.
Now, researchers have boosted the voltage and power output of these tiny generators to the point where they can power electronic components, including a light-emitting diode and a liquid crystal display.
"In the past, our voltage was less than one volt, so we could not power anything," said lead researcher Zhong Lin Wang, a professor at the Georgia Institute of Technology. "But now we can achieve three volts or even as high as five to 10 volts so that we can store the generated charge and use it to power those small devices."
The nano-scale chargers could be ready for commercial use in five years, Wang said.
Some applications include putting the chargers in the sole of a shoe to generate electricity from foot movement. The little power plants could also go in clothing and other fabrics, such as window curtains, or even under train rails to generate large amounts of electricity from train vibrations. Still other uses include insulin pumps implanted in the body and powered by a heartbeat as well as environmental sensors that get their juice from nanogenerators bending in the breeze.
The new nanogenerator is about the size of a fingertip and consists of a sheet of plastic with embedded rows of zinc oxide wires. By using a gold electrode, the researchers integrated thousands of the zinc oxide wires in such a way that their voltage was combined.
This arrangement boosted the device’s power output by three orders of magnitude and its voltage 150 times compared to a device made a year ago. And by stacking five plastic sheets together, the researchers were able to produce one microampere output current at three volts, which is the equivalent of the power of two regular AA batteries .
Wang and his team detail their findings today (Mar. 29) at the American Chemical Society's National Meeting and Exposition in Anaheim, Calif.