High Voltage Output MEMS Vibration Energy Harvester in Mode With PZT Thin Film

The voltage output of PZT thin film microelectromechanical system (MEMS) vibration energy harvester in d₃₁ mode is usually <;1 V at present. In practical applications, rectifier circuit is often utilized after vibration energy harvester. So the low voltage output will cause most of the power loss in rectifier circuit. To solve this problem while ensuring high power output, a d₃₁ mode PZT thin film MEMS vibration energy harvester with high voltage output is designed and fabricated. The proposed harvester consists of five cantilevers and one silicon proof mass. The dimensions of each cantilever are 3 mm x 2.4 mm x 0.052 mm and the proof mass dimensions are 8 mm x 12.4 mm x 0.5 mm. Al/PZT/LaNiO3/Pt/Ti/SiO₂ multilayered films are deposited on a SoI wafer and then the cantilevers are patterned and released. The single cantilever of the harvester produces 21.36-μW average power and 8.58-mW cm^-3 g^-2 power density at 0.5-g acceleration and 228.1-Hz frequency. When the cantilevers are connected in series, the harvester produces 3.94 V rms open circuit voltage with 59.62 μW power for 0.5-g acceleration and 5.72 V rms open circuit voltage with 157.9 μW power for 1-g acceleration at their resonance frequency.