Blinking numbers on a liquid-crystal display (LCD) often indicate that a device's clock needs resetting. But in the laboratory of Zhong Lin Wang at Georgia Tech, the blinking number on a small LCD signals the success of a five-year effort to power conventional electronic devices with nanoscale generators that harvest mechanical energy from the environment using an array of tiny nanowires.
In this case, the mechanical energy comes from compressing a nanogenerator between two fingers, but it could also come from a heartbeat, the pounding of a hiker's shoe on a trail, the rustling of a shirt, or the vibration of a heavy machine. While these nanogenerators will never produce large amounts of electricity for conventional purposes, they could be used to power nanoscale and microscale devices - and even to recharge pacemakers or iPods.
Wang's nanogenerators rely on the piezoelectric effect seen in crystalline materials such as zinc oxide, in which an electric charge potential is created when structures made from the material are flexed or compressed. By capturing and combining the charges from millions of these nanoscale zinc oxide wires, Wang and his research team can produce as much as three volts - and up to 300 nanoamps.
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