A new circuital solution for power harvesting from random and low-amplitude voltages by using bistable mechanical switch

This paper concerns the development of a new strategy for vibration energy harvesting with piezoelectric transduction. The proposed solution is based on nonlinear bistable system; it can collect and store energy from weak and random mechanical vibrations and it is particularly suitable when the alternate output voltage produced by the piezoelectric transducer has a low amplitude, lower then diode threshold. In these situations in fact, it is not possible to use the traditional rectifying methods. The system presented here is composed of a PZT (Lead Zirconate Titanate) layer that produces an alternate voltage in response to the external vibrations, a mechanical bistable switch (driven by the same vibration source) and a storage circuit. The system has been modeled, simulated and experimentally validated showing the improvement in performances correlated with the adoption of the nonlinear (bistable) switch.