Parasitic Power Harvesting


As the power requirements for microelectronics continue decreasing, environmental energy sources can begin to replace batteries in certain wearable subsystems. In this spirit, this effort has examined devices that can be built into a shoe (where excess energy is readily harvested), and used for generating electrical power "parasitically" while walking. Two of these are piezoelectric in nature: a unimorph strip made from piezoceramic composite material and a stave made from a multilayer laminate of PVDF foil. The third is a shoe-mounted rotary magnetic generator. As a self-powered application example, a system had been built around the piezoelectric shoes that periodically broadcasts a 12-bit digital RFID as the wearer walks. Nate Shenk's research explored better matching to the piezo source with a switching regulator. Ongoing work investigates exciting the piezo sources at higher frequency, and more optimal integration of the magnetic generators.