Optimization of a vibrations based electromagnetic MEMS energy harvester

Abstract

This thesis includes the design and fabrication of an electromagnetic energy harvester on Silicon and MP35N metal alloy. The mechanical harvester is a spring-mass-damper system that converts mechanical energy into electrical energy. This project resulted in the development of an optimized design flow for vibration EM energy harvesters utilizing a traversing mass. The harvester, which is the focus of this project, interfaces with a custom built control circuit, which is the interface between the electromagnetic harvester and the power bank. The goal of the project is to optimize the electromagnetic harvester and explore designs for practical implementation. The initial Silicon harvester design results in a matched-load power output of 2.2 mW, and a matched-load power-output density of 1.23 mW/cm3 at 1.1 g with a resonance frequency of 76.3 Hz. Using the optimization scheme developed from the Silicon harvester, the MP35N harvester achieves a matched-load power output of 1.2 mW, and a power density of 1.03 mW/cm3 while drastically decreasing the device footprint. The MP35N harvester is robust enough to withstand drops during assembly process and large transient accelerations. The improved durability also enables the installation of back irons, which shows promise of further improving the power output by bringing the raw output power to 1.9 mW at resonance and with matched load.