Curve-Shaped Anchor for Durability and Efficiency Improvement of Piezoelectric MEMS Energy Harvesters

In this paper we propose a new curve-shaped anchoring scheme to improve the durability and energy conversion efficiency of the piezoelectric MEMS harvesters. In this regard, a doubly clamped curve beam with a mass at its center is considered as an anchor, while a straight beam with proof mass is integrated to the center of this anchor. To the best of our knowledge, thus far no study has been done to assess the fatigue damage, which is actually critical to the micro-sized silicon-based piezoelectric harvesters. We have utilized the Coffin-Manson method and finite element modeling (FEM) to comprehensively study the fatigue lifetime of the proposed geometry. By using a micro-fabrication process, our proposed piezoelectric harvester has been fabricated and its capability in harnessing the vibration energy has been examined experimentally. It is found that the harvested energy can be enlarged by a factor of 2.66, while this improvement is gained by the resonant frequency reduction and failure force magnitude enlargement, in comparison with the conventional geometry of the piezoelectric MEMS harvesters.