A new device developed by researchers from Michigan State University may soon be available for development of wearable devices that harvest energy from walking, touching, or other human motions. The film-like device produces an electrical potential when moved. The researchers showed that it can power an LCD screen, a bank of 20 LED lights, and a keyboard.
Nelson Sepulvida, an associate professor in the Electrical and Computer Engineering Department at Michigan State University, says that the device is made of a thin, film-like material that operates on a principle similar to the piezoelectric effect. The piezoelectric effect is a property of some materials to produce an electric charge in response to stress. However, piezoelectric materials are solid and inflexible, like glass. The MSU group's ferroelectric nanogenerator (FENG) is a flexible material that can be bent and folded.
Although the device has been proved to work in the laboratory, Sepulvida says it will need more development before it can be commercialized. He does not currently have any agreement with a company to produce a FENG for the market at this time.
"At this point we're still trying to understand all the details on how the device operates and works so that we could optimize the power that we could extract from the device and make it more efficient," says Sepulvida. The researchers say they're not sure how much energy the device might be able to produce. However, it is possible to make some back-of-the-envelope estimates based on energies known to be produced by human movement. Sepulvida says, "If we are able to completely harvest the energy that is dissipated from the from the human heel strike, you should be looking at charging your smart phone completely by just regular walking during a day." The group's results are published in the journal Nano Energy.