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Power clothes

A solution to future power shortages may beour own shirts.

BOSTON - Someday, your shirt might be able to power your iPod - just by doing the normal stuff expected of a shirt.

Scientists have developed a way to generate electricity by jostling fabric with unbelievably tiny wires woven inside, raising the prospect of textiles that produce power simply by being stretched, rustled or ruffled by a breeze.

The research, described in the Feb. 14 edition of the journal Nature, combines the precision of ultra-small nanotechnology with the elegant principle known as the piezoelectric effect, in which electricity is generated when pressure is applied to certain materials.

While the piezoelectric effect has been understood at least as far back as the 19th century, it is getting creative new looks now, as concerns about energy supplies are inspiring quests for alternative power sources.

For the research described in Nature, Zhong Lin Wang and colleagues at the Georgia Institute of Technology covered individual fibers of fabric with nanowires made of zinc oxide. These wires are only 50 nanometers in diameter - 1,800 times thinner than a human hair.

Alternating fibers are coated with gold. As one strand of the fabric is stretched against another, the nanowires on one fiber rub against the gold-coated ones on the other, like the teeth of two bottle brushes. The resulting tension and pressure generates a piezoelectric charge that is captured by the gold and can be fed into a circuit.

The allure of the idea is that it doesn't take unusual movement to generate usable electricity. Pretty much anything someone does while wearing a piezoelectric shirt would be productive.

"This work represents a significant achievement," said Charles Lieber, a Harvard University researcher who is pursuing nanotech power generation and was not involved in Wang's project.

Lieber noted that the research also could lead to biological sensors and other nanoscale devices that produce their own power from movement or sound waves. For such nanodevices to be feasible, "harvesting energy from the environment is a key technology," Lieber said.

However, there is one big hurdle to the advent of power shirts. Though zinc oxide makes a nice sunscreen, it's not really waterproof.

The Georgia Tech team must figure out how to protectively coat the nanowires - or else one trip through the washing machine or one rainy day would rob these fabrics of their magic.

Sartorial science

Electric fabric: Georgia Tech scientists have developed a way to generate electricity through the normal rustling of fabric, raising the prospect of clothing that could power personal gadgets.

How it works: Ultra-miniature zinc oxide wires on individual threads of fabric rub against each other, producing a current through the piezoelectric effect. That's the principle in which electricity is created when pressure is applied to certain materials.

Why it's years away: Researchers need to scale this up to sizable pieces of fabric, improve the efficiency of the design and make the threads waterproof.

[Last modified February 20, 2008, 01:20:33]