Wireless sensors are an invaluable part of modern society. No, really—wireless sensors affect your life every day in ways you can't even dream of. The sensors measure environmental pollution, make sure that oil pipelines aren't leaking, measure bridge movement, and even keep track of factory machinery. There's just one hitch: These sensors run on batteries that need to be replaced every so often. And when that means swapping out batteries on hundreds of wireless sensors in, say, an oil pipeline in Alaska, there's a problem.
There are already wireless sensors that power themselves using low-frequency vibrations—the kind created by swaying bridges or foot traffic—but they haven't been all that powerful in the past. But MIT's new energy-harvesting microelectromechanical system (MEMS) translates even the tiniest movements into relatively enormous amounts of power.
The piezoelectric device consists of a bridge-like structure anchored to a microchip on both ends. A layer of piezeoelectric material (i.e quartz or crystal) sits on top of the bridge, and a weight is placed in the middle of it. Unlike other piezeoelectric energy-harvesting devices, this one can respond to a wide range of vibrational frequencies—meaning there are more opportunities to produce power. The MIT researchers estimate that the device, which could cost under $1, can produce 100 times the power of other similarly sized piezoelectric devices.
Wireless sensor systems may be the most immediate application for the technology, but there are other potential uses as well. A group of Stanford students, for example, are working on using piezeoelectric sensors to power certain vehicle functions. If MIT's research pans out, there will be an ever-expanding array of small devices that can be powered by these sensors—and these will slowly but surely take pressure off traditional energy supplies.
[Image: Arman Hajati]