Improving power output for vibration-based energy scavengers

Pervasive networks of wireless sensor and communication nodes have the potential to significantly impact society and create large market opportunities. For such networks to achieve their full potential, however, we must develop practical solutions for self-powering these autonomous electronic devices. We´ve modeled, designed, and built small cantilever-based devices using piezoelectric materials that can scavenge power from low-level ambient vibration sources. Given appropriate power conditioning and capacitive storage, the resulting power source is sufficient to support networks of ultra-low-power, peer-to-peer wireless nodes. These devices have a fixed geometry and - to maximize power output - we´ve individually designed them to operate as close as possible to the frequency of the driving surface on which they´re mounted. In this paper, we describe these devices and present some new designs that can be tuned to the frequency of the host surface, thereby expanding the method´s flexibility. We also discuss piezoelectric designs that use new geometries, some of which are microscale (approximately hundreds of microns).