One of the first ways we harnessed static electricity was to drag our shoes on the carpeted floor in the dry air of winter, then touch our brother’s ear. In this little experiment, thousands of volts discharged from the positively charged finger to the negatively charged ear, micro-amps [µA] of electricity.
Researchers at Georgia Tech have created a device that harnesses this kind of energy to do something more beneficial, like charge a mobile phone.
When your mobile phone is in your pocket and you walk around, that little bit of friction, coupled with a new nanogenerator, produces enough static electricity to charge the battery, or even other devices, such as medical implants or hearing aids.
Zhong Lin Wang, a professor of materials science at Georgia Tech, has been focusing on piezoelectric materials that generate an electrical voltage under mechanical stress, amplifying the effect by making materials structured at the nanoscale.
The new generator is made up of thin-film layers of plastic and metal, when flexed together, create a small electrical current. Nanoscale patterns on the films increase the surface area significantly, in the case of a one square centimeter [cm2], up to eight milliwatts. This is enough to power a pacemaker. A 25 cm2 piece of the same material is powerful enough to charge a mobile phone’s lithium-ion battery.
Commercial application could depend on if the effect can be reproduced outside the lab. “They need to demonstrate that this can generate power from mechanical vibrations in real life,” says Jiangyu Li, professor of mechanical engineering at the University of Washington in Seattle. Recovering the energy that we generate while doing everyday tasks could make even personal electronic devices and medical devices sustainable.