Researchers have discovered yet another way to harvest small amounts of electricity from motion in the world around us this time by capturing the electrical charge produced when two different kinds of plastic materials rub against one another. Based on flexible polymer materials, this "triboelectric" generator could provide alternating current (AC) from activities such as walking.
The triboelectric generator could supplement power produced by nanogenerators that use the piezoelectric effect to create current from the flexing of zinc oxide nanowires. And because these triboelectric generators can be made nearly transparent, they could offer a new way to produce active sensors that might replace technology now used for touch-sensitive device displays.
"The fact that an electric charge can be produced through this principle is well known," said Zhong Lin Wang, a Regents professor in the School of Materials Science and Engineering at the Georgia Institute of Technology. "What we have introduced is a gap separation technique that produces a voltage drop, which leads to a current flow, allowing the charge to be used. This generator can convert random mechanical energy from our environment into electric energy."
The research was funded by the National Science Foundation, the Department of Energy and the U.S. Air Force. Details were reported in the June issue of the journal Nano Letters. In addition to Wang, authors of the paper included Feng-Ru Fan, Long Lin, Guang Zhu, Wenzhuo Wu and Rui Zhang from Georgia Tech. Fan is also affiliated with the State Key Laboratory of Physical Chemistry of Solid Surfaces at Xiamen University in China.
The triboelectric generator operates when a sheet of polyester rubs against a sheet made of polydimethysiloxane (PDMS). The polyester tends to donate electrons, while the PDMS accepts electrons. Immediately after the polymer surfaces rub together, they are mechanically separated, creating an a
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