Optimization of a vibrating MEMS electromagnetic energy harvester using simulations

International audience; Nowadays, wireless sensor networks (WSN) are becoming essential in our daily life. However, a major constraint concerns the energy power supply. Indeed, batteries need to be recharged or replaced often which implies a limited lifetime for WSN nodes. One alternative consists in harvesting mechanical energy from surrounding vibrations of the environment. Using finite element simulations, we report here a complete guideline to optimize a MEMS electromagnetic energy harvester consisting of an in-plane vibrating silicon frame supporting an array of micromagnets that faces a static 2D micro-coil. The dimensioning of the magnet array and the specific design of the coil are addressed, considering patterned 50 µm thick NdFeB films with out of plane magnetization. The optimization of the electromechanical coupling which allows to efficiently convert the energy results from a trade-off between the high magnetic flux gradients produced by the micromagnets and the maximum number of turns of the facing coil.