Design and analysis of a microcantilever system for a vibration based mems piezoelectric energy harvester

A piezoelectric based MEMS energy harvester has been designed as a replacement for the conventional rechargeable batteries/cells, where frequent replacements and maintenance of power source are being required in remote applications. In the recent years, cantilever-based designs are gaining popularity in the field of MEMS piezoelectric vibration energy harvester, due to its small size, simple design, power efficiency and stability. In cantilever-based vibration energy harvesters, the active piezoelectric area near the clamped end can accumulate maximum strain-generated electrical charge due to the conversion of mechanical vibrations into electrical energy, while the free end is used to house the proof mass to improve stable power output without compromising the effective area of the piezoelectric generator. This work deals with the design and simulation of the MEMS-based energy harvester using COMSOL Multiphysics. In this work, two designs were modeled and analysed for their mechanical and electrical properties. In the Design-I, four variable-size cantilevers were fixed on a diagonally-mounted beam on a square fixture, whereas in Design-II four equal-size cantilevers were mounted on a Z-shaped frame fixed diagonally on a square fixture. In both the designs, Aluminium Nitride and gold layer were used as a piezoelectric material and voltage tapper, respectively. Both the designs were characterized for the Von Mises stress, displacement and output voltage. The results of this study exhibited that the design-II was found to be a better design for energy harvesting than the design-I, which is evident from the maximum output voltage, stress withstanding capacity and maximum displacement characteristics. This simulation work will be realized into practical energy harvesters, after optimizing the various design parameters during the fabrication phase. The results of this simulation study will find future scope of MEMS piezoelectric harvesters in the fields of power MEMS and Green Technology.