Analysis and design of a self-powered piezoelectric microaccelerometer

Power consumption is a critical concern of many sensors used in diversified applications, especially where the replacement of batteries is impossible or inconvenient. Strain energy harvesting technique is an attractive approach to solve this problem using piezoelectric materials. The feasibility of a self-powered piezoelectric microaccelerometer system using lead zirconate titanate (PZT) thin film is studied in this paper. Since the electromechanical coefficient d33 of PZT is larger than d31, and the transverse (33 mode) mode is also easier to fabricate, our design and analysis are focused on the transverse mode in constructing the PZT-based self-powered microsystem. The PZT-based cantilever structure with interdigitated electrodes and silicon seismic mass at the free end are designed to have specific resonance frequencies ranging from tens to thousands of hertz. The capability of energy storage and acceleration sensitivity in the proposed microaccelerometer are concurrently evaluated. A trade-off exists between these two major functions and the desirable operating frequency of the proposed system, i.e., the compromise depends on the demands of particular applications.