Design, fabrication and test of integrated micro-scale vibration-based electromagnetic generator

This paper discusses the design, fabrication and testing of electromagnetic microgenerators. Three different designs of power generators are partially micro-fabricated and assembled. Prototype A having a wire-wound copper coil, Prototype B, an electrodeposited copper coil both on a deep reactive ion etched (DRIE) silicon beam and paddle. Prototype C uses moving NdFeB magnets in between two micro-fabricated coils. The integrated coil, paddle and beam were fabricated using standard micro-electro-mechanical systems (MEMS) processing techniques. For Prototype A, the maximum measured power output was 148 nW at 8.08 kHz resonant frequency and 3.9 m/s² acceleration. For Prototype B, the microgenerator gave a maximum load power of 23 nW for an acceleration of 9.8 m/s², at a resonant frequency of 9.83 kHz. This is a substantial improvement in power generated over other micro-fabricated silicon-based generators reported in literature. This generator has a volume of 0.1 cm³ which is lowest of all the silicon-based micro-fabricated electromagnetic power generators reported. To verify the potential of integrated coils in electromagnetic generators, Prototype C was assembled. This generated a maximum load power of 586 nW across 110 Ω load at 60 Hz for an acceleration of 8.829 m/s².