Boots for power

There are boots for wading, walking, hiking and skiing. But how about boots for power?
SRI International, a research firm in Menlo Park, Calif., is working with the Defense Department to create a shoe that will convert the mechanical energy of walking into electric power to charge up gadgets, batteries and other devices.
At the heart, or rather sole, of the experimental foot-ware is a heel made of a special elastic polymer. A tiny battery positively charges one side of the flexible material and the other negatively. As the material is compressed and released — such as by the foot pressure generated during walking — the distance between the positive and negative sides change, which in turn creates electricity.