for National Geographic News
Nanotech fabric that can harvest energy from motion could one day lead to clothing that can power portable electronics, researchers say.
Zhong Lin Wang and colleagues at Georgia Institute of Technology designed the new fabric based on a phenomenon called the piezoelectric effect.
This effect occurs when mechanical pressure is applied to certain materials that have crystalline structures in such a way that it produces a small electric charge.
Wang's team lined textile fibers with piezoelectric nanowires arranged like the bristles on a bottlebrush. When a person walks around wearing the material, the wires rub together and generate electricity.
"Bending the wires creates a piezoelectric field potential," Wang said. (Related news: "Knee-Brace Generator Offers Portable 'Power Plant'" [February 7, 2008].)
The researchers estimated that their material could eventually generate up to 80 milliwatts of power for each square meter (about 11 square feet) of fabric.
An average digital music player or cell phone, by contrast, uses a few hundred milliwatts or more.
So while your future sweat suit may not charge up your iPod, it could power tiny sensors that keep track of your vital signs as you run.
And the use is not limited to clothing, Wang added. The technique can be applied to any surface that picks up vibration, such as engines, tires, or even swaths of cloth catching the wind.
For their research, which is described in tomorrow's issue of the journal Nature, the Georgia Tech team first grew nano-size wires of zinc oxide around Kevlar fibers.
The wires were 50 nanometers thick, or about a thousand times thinner than a single human hair.
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