A Hybrid Piezoelectric and Electromagnetic Broadband Harvester with Double Cantilever Beams

Abstract

Vibration-energy harvesting is an effective strategy for replacing batteries and provides a long-term power supply to microelectronic devices. Harvesting vibration energy from human motions has attracted research attention in recent years. Here, a novel low-frequency hybrid piezoelectric and electromagnetic broadband harvester is proposed. Two parallel piezoelectric cantilever beams support the harvester and capture environmental vibration energy based on the piezoelectric effect. A permanent magnet is connected by springs to the two beams, and a fixed coil surrounds the moving permanent magnet, enabling energy conversion via the electromagnetic effect and the proof mass. The parameters influencing the output power of the harvester are optimized numerically to boost the harvester's performance. The output power of the proposed hybrid harvester is compared with that of a piezoelectric harvester and an electromagnetic harvester. The simulation results show that the output power is significantly higher for the hybrid harvester than for the piezoelectric and electromagnetic harvesters, and the bandwidth is broader owing to the double cantilevers. An experiment is conducted using a prototype of the hybrid harvester to evaluate its output power. The results show multiple resonant peaks, an extended bandwidth, and a maximum power of 6.28 mW. In contrast, the maximum harvested power of the piezoelectric harvester is only 5.15 mW at 9.6 Hz.