Nanomaterial in shoes, cloths converts movement into power
New nanomaterials achieve 80 percent efficiency at converting mechanical energy (as that being generated from walking) into electricity; a single PZT crystal, implanted into a shoe, could theoretically generate 10 milliwatts of power: enough to operate 10 iPods; the goal is to embed the crystals in shoes and cloths of both soldiers and civilians so that the wearer’s movements would power whatever electronic gear he or she carries
What if you could power your iPod not by using a battery — but by converting the energy from walking or jogging into electricity? This is the idea behind new nanotechnology research funded by the U.S. intelligence community that could potentially turn spies into self-powered electricity machines.
Katie Drummond writes that Professor Michael McAlpine of Princeton University — who won funding as part of the Intelligence Community Post-Doctoral Fellowship program — is leading the effort. His research uses a type of piezoelectric crystal, called PZT, which produces an electric current when exposed to pressure.
Until now, researchers have been unsure how to make the crystals biocompatible. Manufacturing piezoelectric crystals requires heat that can exceed 1,000 degrees, so they are tough to embed into temperature-sensitive materials such as rubber or plastic. So McAlpine’s team used nanotechnology, creating ribbons of the crystals on a substrate — 100 strips in a single millimeter — and then embedding them into silicone rubber. The result is a flexible strip of “piezo-rubber” which is 80 percent efficient at converting mechanical energy (as that being generated from walking) into electricity.
McAlpine told Drummond that a single PZT crystal, implanted into a shoe, could theoretically generate 10 milliwatts of power: enough to operate 10 iPods. “Now imagine that instead of a single crystal, the entire shoe’s insole is lined with strips of PZT, that can convert most of the body’s energy into usable power,” Drummond writes.
Next up for the intelligence community-funded researchers are prototype devices and some number crunching, to figure out exactly how much money the government agency could save if it switched to crystal-based people power. More than just charging up intelligence gadgets, the research has applications across the military, including easy power harvesting for troops working in isolated, far-out terrain. McAlpine is also anticipating widespread civilian use. Most importantly, perhaps, is replacing batteries on implanted medical devices, like pacemakers. The strips would harness power from the lungs to control the heart, and work perpetually without needing replacement parts.
“That technology is likely a decade away, but the team anticipates producing sensors that operate using the piezo-rubber within a few months,” Drummond concludes.
