Micro-Electrostatic Vibration-to-Electricity Converters

 S. Roundy, P. K. Wright, and K.S.J. Pister

Proceedings of IMECE’02
2002 ASME International Mechanical Engineering Congress & Exposition
New Orleans, Louisiana 17-22, 2002

Advances in low power VLSI design, along with the potentially low duty cycle of wireless sensor nodes open up the possibility of powering small wireless computing devices from scavenged ambient power. Low level vibrations occurring in typical household, office, and manufacturing environments are considered as a possible power source for wireless sensor nodes. This work focuses on the design of electrostatic vibration-to-electricity converters using MEMS fabrications technology. Detailed models of three different design concepts are developed. The three design concepts are evaluated and compared based on simulations and practical considerations. A formal optimization of the preferred design concept is performed, and a final design is produced using the optimal design parameters. Simulations of the optimized design show that an output power density of 116 µW/cm3 is possible from input vibrations of 2.25 m/s2 at 120 Hz. Test devices have been designed for a Deep Reactive Ion Etching (DRIE) process that etches MEMS structures into the top layer of a Silicon On Insulator (SOI) wafer. The devices are currently being fabricated.