Development of a Solid-State Microhydraulic Energy Harvesting Mechanism for Heel Strike Power Harvesting.

摘要

A Microhydraulic Transducer (MHT) device was developed with the goal of extracting energy from heel strike motion. The required power output is approximately 1W, with an associated power density of approximately 0.1-1W/kg. The MHT relies on the incorporation of discrete piezoelectric elements into a microfabricated device to produce compact, high stiffness actuation at high frequencies. These piezoelectric elements. in conjunction with a piezoelectric piston. enable the design of a stiff, efficient fluidic to electric energy conversion mechanism with high power density. Using this mechanism in combination with hydraulic amplificaton, piezoelectric hydraulically amplified valves were produced that made it possible to create pulsing fluid pressure on a piezoelectric piston, and hence extract electrical power. The device relies on the DRIE fabrication of high-strength silicon membranes to form pistons with membrane tethers. These pistons are the moving elements of the device. A final device was built and tested, with a maximum power output of I mW measured from the piezoelectric piston at a differential pressure of 450kPa. Good agreement with models was obtained and, although the device tested had a design limitation unaccounted for in the original modeling, future devices based on this concept should be able to reach the original design goals.