Imagine charging your iPod just by shouting into it, or powering a blood glucose monitor with your pulse. Such technologies aren’t far off: In the latest rendition of tiny, energy-scavenging devices, scientists have developed a prototype sensor that produces enough electrical charge when flexed mechanically to transmit a wireless signal several meters.
With further improvements, the new device might be part of an array of sensors that can monitor the strength of a bridge, for example, while powering itself with the vibrations of trucks rumbling overhead, says Zhong Lin Wang of Georgia Tech, who led the new work.
The device is powered by zinc oxide nanowires that generate charge when bent, a property found in some crystals such as quartz and even in cane sugar. Such piezoelectric materials (from the Greek piezein, for “squeeze” or “push”) have already found their way into everyday devices — some cars, for example have piezoelectric crash sensors in the airbag wiring.