A novel up-converting mechanism based on double impact for non-linear piezoelectric energy harvesting

In this paper we show the importance of double impact in an up-converting mechanism by using a resonant low-frequency driving beam across a high-frequency piezoelectric beam, to enhance the electrical output power in a vibration energy harvesting (VEH) system suitable for ambient vibrations. The main advantage of this device is its nearly constant output voltage between impacts compared to other VEH systems using up-converting mechanisms whose output voltages decay abruptly after impact. With the proposed design, the optimum electrical load of the system is substantially lower compared to traditional low-frequency VEH systems. This mechanism improves the energy transfer to some transducers and electronic interfaces with low input impedances, attaining optimal efficiency.