As much as ten watts of power is dissipated as heat every time someone takes a step.  Mobile devices like phones use between one and fifteen watts.  Sound promising?

Nature News reports on developing technology that would make charging your electronics on the go a walk in the park.  Tom Krupenkin and Ashley Taylor, mechanical engineers at the University of Wisconsin-Madison, are working on a technology that may someday be integrated into a pair of shoes to power electronics such as a phone or MP3 player.  The technique they are using is called electrowetting.

Electrowetting typically uses an electric charge to deform a drop of liquid, but when they threw the process into reverse, it generated electricity instead.  By deforming liquid drops between electrode plates, a charge can be generated.  That charge creates an electrical current when included in a full circuit.

There have been attempts to harness walking energy through piezoelectrics, materials that produce electricity when compressed or bent, but only a few milliwatts have been extracted this way.  Krupenkin used a dielectric – an insulator that can be polarized in an electric field – called tantalum oxide to coat the electrodes, and liquid drops lof mercury or a gallium-based alloy called galinstan.

The more droplets used, the more power that can be generated.  Krupenkin estimates that it would take 1,000 droplets to generate ten watts and power anything from a cell phone to a military radio.  There is also hope for this technology’s use in developing countries where electricity is more scarce.

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