The irresistible concept of harvesting the very power we humans generate merely by moving is getting a fresh approach from two University of Wisconsin researchers. They’re going beyond familiar kinetic energy conversion methods such as electromagnetic, piezoelectric or electrostatic (like the nPower PEG) to a process called “reverse electrowetting,” which the university reports could function right in your shoe to produce much more power than earlier methods – enough to run a laptop computer.
Tom Krupenkin and J. Ashley Taylor started with electrowetting, a phenomenon we’re seeing used in e-ink applications these days, whereby applying a charge to a surface can essentially activate the liquid on that surface. Krupenkin and Taylor found that with a using a particular type of nanostructured substrate, they could turn this process around. “Energy generation is achieved through the interaction of arrays of moving microscopic liquid droplets with a novel multilayer thin film,” is how they put it in their paper in the journal Nature Communications.
What’s exciting is this doesn’t appear to be one of those cool but highly academic breakthroughs that won’t have practical applications; Krupenkin and Taylor have formed a company called InStep NanoPower with the goal of commercializing what they call a “radically new high-power energy harvesting technology.” They say the most promising application of the technology would be to embed the device into footwear, where energy normally lost as heat could provide up to 20 watts of power, which could be stored in a battery included with the unit. They see a couple of ways of using the power that’s harvested.
First, you could use it directly to power devices – “from smartphones and laptops to radios, GPS units, night-vision goggles and flashlights” – by plugging in or using wireless inductive coupling. But they also offer the intriguing idea of turning your shoe into a Wi-Fi hotspot. The benefit here is that by using your presumably nearby shoe as a “middleman” between mobile devices and a wireless network, you could dramatically reduce the amount of power your mobile devices use, increasing their operating time on a single charge.