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When it comes to clothes, University of California, Berkeley researchers have given new meaning to the term "power suit." They have created energy-scavenging nanofibers that could one day be woven into clothing and textiles. "This technology could ev

When it comes to clothes, University of California, Berkeley researchers have given new meaning to the term "power suit." They have created energy-scavenging nanofibers that could one day be woven into clothing and textiles. "This technology could eventually lead to wearable 'smart clothes' that can power hand-held electronics through ordinary body movements," said mechanical engineering professor Liwei Lin, head of the team that developed the fiber nanogenerators. These nano-sized generators have "piezoelectric" properties allowing them to convert into electricity the energy created through mechanical stress, stretches and twists. "Because the nanofibers are so small, we could weave them right into clothes with no perceptible change in comfort for the user," Lin notes.

You can read more in this month's issue of the ACS journal Nano Letters,.a peer-reviewed journal published by the American Chemical Society. This isn't the first approach to using clothes to using the energy from people's movements to power small electric devices. Other research teams have previously made nanogenerators out of inorganic semiconducting materials, such as zinc oxide or barium titanate. "Inorganic nanogenerators – in contrast to the organic nanogenerators we created – are more brittle and harder to grow in significant quantities," Lin said.

The tiny nanogenerators have diameters as small as 500 nanometers, or about 100 times thinner than a human hair and one-tenth the width of common cloth fibers. By tugging, the researchers repeatedly generated electrical outputs ranging from 5 to 30 millivolts and 0.5 to 3 nanoamps. There was no noticeable fiber degradation after stretching and releasing the nanofibers for 100 minutes at a frequency of 0.5 hertz (cycles per second).

The researchers demonstrated energy conversion efficiencies as high as 21.8%, with an average of 12.5 %. "We think the efficiency likely could be raised further," Lin said. "For our preliminary results, we see a trend that the smaller the fiber we have, the better the energy efficiency. We don't know what the limit is."

Lin's team at UC Berkeley pioneered the near-field electrospinning technique used to create and position the polymeric nanogenerators 50 micrometers apart in a grid pattern. This technique enables greater control of the placement of the nanofibers onto a surface, allowing researchers to properly align the fiber nanogenerators so that positive and negative poles are on opposite ends, similar to the poles on a battery. Without this control, the negative and positive poles might cancel each other out and reducing energy efficiency.

Personal thoughts

Talk about multitasking! While bicycling to work, playing basketball in the driveway, and just walking around you could be charging the batter of your cell phone or other personal electronics.

Wouldn't it be great if high tech clothes resulted in at least a partial return of the textile industry to the United States? Once this industry employed hundreds of thousands of people.

I find it interesting that these mechanical engineers are publishing in a chemistry research journal. As the ACS says, "Chemistry is the central science."


John K. Borchardt

Dr. Borchardt is a consultant and technical writer. The author of the book “Career Management for Scientists and Engineers,” he writes often on career-related subjects.