The core of MicroGen's chips is a one-centimeter-squared array of tiny silicon cantilevers that oscillate when the chip is jostled. At the base of the cantilevers is a bit of piezoelectric material: when it's strained by vibrations, it produces an electrical potential that can be used to generate electrical current. The cantilever array is mounted on top of a postage-stamp-sized, thin-film battery that stores the energy it generates. The current passes from the piezoelectric array through an electrical device that converts the current to a form compatible with the battery. When the chip is shaken by, say, the vibrations of a rotating tire, it can produce about 200 microwatts of power.

MicroGen systems, Inc. is developing a suite of products based on its proprietary piezoelectric vibrational energy harvester (PZEH) technology. These low cost, long lifetime (over 20 years) Micro-ElectroMechanical Systems (MEMS) are micro-power sources that extend rechargeable battery lifetime or will eliminate the need for batteries altogether. Credit: MicroGen Systems