Innovative piezoelectric cantilever beam shape for improved energy harvesting

Piezoelectric cantilevered beams have been used as a MEMS energy harvester for the last decade because of their less natural frequencies in comparison with other types of boundary conditions. Defining a new shape of cantilever beam to reduce the natural frequency in compared with conventional one is so worthwhile because it causes more flexible bending stiffness and a larger bonding area of piezoelectric layer. So, higher efficiency of the PZT energy harvester can be expected. In order to achieve this goal, a new S-shape PZT cantilever energy harvester is proposed. In this study, the software COMSOL Multiphysics is used to analysis and investigate the characteristics of the suggested model. Preliminary results from modal analysis confirm that in the same volume of mass and effective length of the straight and S-shape beam, the proposed model is more flexible and experiences several natural frequencies which are less than second natural frequency of the conventional cantilevered energy harvester. It is predicted, by mechanical and electrical analyzing, the proposed model produces much higher output voltage than the conventional flat vibration energy harvester, mainly because of lower resonance frequencies. In better word, the proposed model needs less amplitude of excitation force for its maximum efficiency.