Harvesting the Ultimate Electrical Power From MEMS Piezoelectric Vibration Energy Harvesters: An Optimization Approach

Optimized MEMS piezoelectric vibration energy harvesters with maximum possible power generation have been proposed. The energy harvesters work based on the transduction of the applied vibration induced stress on the cantilever beams into the electrical power. Particle swarm optimization approach has been used to design the optimum unimorph and bimorph structures. The optimization has been done for different combinations of the top and bottom piezoelectric layers in bimorph energy harvesters. The geometries of the proposed structures and their harvested powers before and after the optimization have been calculated and compared. The optimization parameters have been chosen so that asymmetric structures with partial coverage of piezoelectric layers would be investigated. The results show that the proposed structures serve as the maximum power generators and provide the largest possible electrical power. In order to limit the beam free end displacement, a guided two beam design has been proposed and optimized. The proposed bimorph guided two beam energy harvester could achieve the minimum displacement which has a key effect on the lifetime of the energy harvesters.