Voice vibration could recharge mobile phones
Published: 04 Dec 2008 13:04 GMT
A variety of off-grid devices use the wind, the sun or fuel cells to power up small electronics. Now, researchers at Texas A&M University say they have made the initial step towards letting people charge their mobile phone by just talking into it, eliminating the need for batteries or cords.
This would be made possible with 'piezoelectricity', in which a mechanical force is converted to electricity. Some cigarette and barbeque lighters use this: when a button is punched, pressure on a crystal within produces voltage, creating a spark.
In principle, the pressure needed to produce this voltage, and power a device, could come from sound vibrations.
Crafting such piezoelectric electronics would require sensors with a specific size of crystal or ceramic material. Researchers at Texas A&M University say they have taken an early step by identifying a sweet spot at which a crystal could produce energy.
The capability of barium titanate crystals to harvest power doubles when they're about 23nm in size, according to the researchers' analysis, led by engineer Tahir Cagin. A human hair, by contrast, is about 100,000nm wide.
However, it could be years or even decades before scientists and entrepreneurs apply the findings to consumer products, Cagin said.
"There are limitations to how much power you can generate at a given size," Cagin said. He added that an iPod or mobile phone may require nanosensors at a scale and composition different from what his research suggested.
For now, at least, wind-up radios, shake flashlights and other devices that use kinetic energy for power are available. Products under development include a dance-powered iPod charger that could be worn on an arm, and M2E Power is building motion-powered gadget chargers that could come to market in 2009.
On a larger scale, people are increasingly using piezoelectricity for off-grid, 'green' power. Dancing feet produce electricity at a nightclub in the Netherlands, and a San Francisco nightclub could follow suit. Meanwhile a gym in Oregon has rigged some exercise equipment to generate 750 watts.
The journal Physical Review B this autumn published Cagin's research, in which engineers at the University of Houston also participated.
Credit: Could nanotech create speech-powered phones? from CNET News
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