Optimizing on-chip piezoelectric energy scavenging for integration of medical sensors with low-power wireless networks

Vibrational energy scavenging using piezoelectric material is a viable method to provide sufficient energy for low-power wireless sensor networks. The applications for such devices in hospital settings as well as in vivo are abundant. Current devices are limited by both their design and material selection. This paper will address optimizing the design of microscale devices by showing how the device strains under input vibrations are directly proportional to its power output, and by proposing alternate designs which increase the strain distribution over more of the device volume. Finite element modeling (ANSYS (R)) was used to determine the strain distribution in a cantilever, modified cantilever, trapezoid, and spiral shaped piezoelectric microscale energy scavenging system. The increase in strain under uniform acceleration was determined to be 0, 29.2, 37.8, and 87.0%, respectively, over that of a simple cantilever.