Harvest usable energy with each step

Tom Krupenkin and J. Ashley Taylor reported the application of a unique electrostatic capacitor. In this study, conducting droplets are suspended between electrodes coated with a thin dielectric film. A capacitor is formed between the electrodes and conducting droplets with an insulating gap on the order of 10-50 nanometers. When incorporated into the sole of a shoe, this "reverse electrowetting" approach was shown to produce up to 1000 times more power than comparable methods. The researchers have formed a company, InStep NanoPower, to help bring the technology to market. Read more at Science NOW.

Abstract
Over the last decade electrical batteries have emerged as a critical bottleneck for portable electronics development. High-power mechanical energy harvesting can potentially provide a valuable alternative to the use of batteries, but, until now, a suitable mechanical-to-electrical energy conversion technology did not exist. Here we describe a novel mechanical-to-electrical energy conversion method based on the reverse electrowetting phenomenon. Electrical energy generation is achieved through the interaction of arrays of moving microscopic liquid droplets with novel nanometer-thick multilayer dielectric films. Advantages of this process include the production of high power densities, up to 103 W m−2; the ability to directly utilize a very broad range of mechanical forces and displacements; and the ability to directly output a broad range of currents and voltages, from several volts to tens of volts. These advantages make this method uniquely suited for high-power energy harvesting from a wide variety of environmental mechanical energy sources.

Krupenkin, T. and Taylor, J.A. Reverse electrowetting as a new approach to high-power energy harvesting. Nature Communications, 2:448 (2011). (Link)