Towards Hysteretic Power Microswitches for Efficient Vibration Energy Harvesting Sensor Systems

Interest in vibration energy harvesting technologies has increased significantly in the last decade, primarily due to the possibility of realizing ultra-low power sensor and communication circuits. In such low-power applications, it is paramount to maximize the efficiency of the harvesting system. Here, we propose the use of a simple MEMS cantilever as a power regulating hysteretic switch that allows discharge of the collected voltage within a predetermined range through pull-in and pull-out. This approach enables voltage regulation of the load circuit without the need for any external fixed sources and minimizes losses. We have developed a model to characterize the motion of the beam and verified it by comparing to existing experimental and calculated results. The beam is designed to be immune against possible environmental shock forces; immunity may be increased by deliberately introducing squeezefilm damping. However, there is a tradeoff between shock force immunity and switching time.