Power Shirt Generates Electricity as Wearer Moves

Research from Georgia Institute of Technology published in the February 14 issue of the journal "Nature" details how pairs of textile fibers covered with zinc oxide nanowires can generate electrical current.

Combining current flow from many fiber pairs woven into a shirt or jacket could allow the wearer’s body movement to power a range of portable electronic devices. The fibers could also be woven into curtains, tents or other structures to capture energy from wind motion, sound vibration or other mechanical energy.

"The fiber-based nanogenerator would be a simple and economical way to harvest energy from physical movement," said Zhong Lin Wang, a Regents professor in the School of Materials Science and Engineering at the Georgia Tech. "If we can combine many of these fibers in double or triple layers in clothing, we could provide a flexible, foldable and wearable power source that, for example, would allow people to generate their own electrical current while walking."

The research was sponsored by the National Science Foundation, the U.S. Department of Energy and the Emory-Georgia Tech Nanotechnology Center for Personalized and Predictive Oncology.

The microfiber-nanowire hybrid system builds on the nanowire nanogenerator that Wang’s research team announced in April 2007. That system generates current from arrays of vertically-aligned zinc oxide (ZnO) nanowires that flex beneath an electrode containing conductive platinum tips. The nanowire nanogenerator was designed to harness energy from environmental sources such as ultrasonic waves, mechanical vibrations or blood flow.

The nanogenerators developed by Wang’s research group take advantage of the unique coupled piezoelectric and semiconducting properties of zinc oxide nanostructures, which produce small electrical charges when they are flexed.

Professor Zhong Lin Wang holds a prototype microfiber nanogenerator. (Photo by Gary Meek courtesy Georgia Tech)

The microfiber generators rely on the same principles, but are made from soft materials and designed to capture energy from low-frequency mechanical energy. They consist of DuPont Kevlar fibers on which zinc oxide nanowires have been grown radially and embedded in a polymer at their roots, creating what appear to be microscopic baby-bottle brushes with billions of bristles. One of the fibers in each pair is also coated with gold to serve as the electrode and to deflect the nanowire tips.

"The two fibers scrub together just like two bottle brushes with their bristles touching, and the piezoelectric-semiconductor process converts the mechanical motion into electrical energy," Wang explained. "Many of these devices could be put together to produce higher power output."

Wang and collaborators Xudong Wang and Yong Qin have made more than 200 of the fiber nanogenerators.

As a next step, the researchers want to combine multiple fiber pairs to increase the current and voltage levels and improve conductance of their fibers.

But as it is designed right now, the power shirt could not be washed. Zinc oxide is sensitive to moisture, so in real shirts or jackets, Wang said, the nanowires would have to be protected from the effects of the washing machine.

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