Photos of the Day: Body-Powered Devices
Zhong Lin Wang, Ph.D., and his team have set out to transform the way we look at mechanical energy. Conventional energy sources have so far relied on century-old science that requires scattered, costly power plants and a grid to distribute electricity far and wide. A couple of years ago, Wang's team at the Georgia Institute of Technology was working on a miniature generator based on an energy phenomenon called the piezoelectric effect, which is electricity resulting from pressure. But to their surprise, it produced more power than expected. They investigated what caused the spike and discovered that two polymer surfaces in the device had rubbed together, producing what's called a triboelectric effect — essentially what most of us know as static electricity.
Building on the fortuitous discovery, Wang then developed the first triboelectric nanogenerator, or "TENG." He paired two sheets of different materials together — one donates electrons, and the other accepts them. When the sheets touch, electrons flow from one to the other. When the sheets are separated, a voltage develops between them.
His group has incorporated TENG into shoe insoles, whistles, foot pedals, floor mats, backpacks and ocean buoys for a variety of potential applications.