Design And Simulation Of MEMS Based Hybrid Vibration Energy Harvester

The development of wireless sensor networks require more stable energy supply, which goes beyond the limit of traditional batteries. MEMS-based energy-harvesting technology can convert the environmental vibration energy and transform to electricity, with long life-span and no need to replace frequently. As it realizes self-power and it is a promising solution for the energy supply of MEMS-based sensors instead of traditional batteries.Base on the mass-spring-damping linear system theory, two kinds of main vibration energy harvesting mechanisms which are piezoelectric mechanism and capacitive mechanism have been analysis. Their mathematic models have been build up respectively. Further more, a new hybrid vibration energy harvester which combines the harvesting mechanism of piezoelectric energy harvester and capacitive energy harvester has been presented in this thesis.Some critical structure dimensions of the vibration energy harvester have been discussed, as well as the mechanical quality factor. The vibrant part of the device has been parametric designed, and the relationship between the structure parameters, the maximum vibration amplitude and the first natural frequency is obtained by utilizing finite element method.According to the mathematic model proposed by this paper, the performances of these energy harvesters have been simulated by MATLAB/SIMULINK. The results show that the piezoelectric energy harvester is more suitable for the low-frequency environment among all kind harvesters; Capacitive energy harvester has better performance under the high-frequency vibration environment. The hybrid energy harvester, which has the better performance under low-frequency vibration environment than piezoelectric energy harvester and capacitive energy harvester that adopt the same structure, is feasible to same extent.In micro-fabrication process part, a complete MEMS process flow to fabricate the hybrid energy harvester is presented. A series of experiments have been carried out to verify some key process steps. PZT thin film with 1μm thickness has been obtained. The method which can precisely control the depth of the grave and the height of the stopper in the glass wafer has been mastered. The triple stack (glass/silicon/glass) anodic bonding process has been performed in two stages.