Fraunhofer IPMSEnergy power plant in the sole of the shoe

... are based on electroactive polymers. These are small enough to fit into the soles of shoes. Compared to piezoelectric solutions, the polymer films used are able to convert mechanical energy efficiently even at low frequencies. According to the Fraunhofer researchers, the energy converter embedded in a shoe produces several µW per second under the pressure load of a runner. The converter circuit in the Fraunhofer researchers' demonstrator is tuned to ...