Rolling Mass for Wide bandwidth Vibration Energy Harvesting

The narrow bandwidth of MEMS vibration energy harvesting devices is considered a major challenge that limits the implementation of the devices into real-life applications. This paper reports on experimental validation of widening the bandwidth of a piezoelectric cantilever using a movable mass. The widening effect is caused from a change in center of gravity caused from movable metallic spheres. The goal of this study was to investigate the effects of the amount of movable mass by varying the number of spheres and the size of the spheres. The results demonstrated a significant increase in bandwidth from 1.8 Hz to 10.6 Hz for the control (no movable component) and eight embedded 10mm spheres respectively. Keeping the overall amount of movable mass to be similar but decreasing the size and increasing the number of spheres resulted in a further increase in bandwidth to 13.4 Hz.