MEMS Energy Harvester Utilizing a Multi-pole Magnet and a High-aspect-ratio Array Coil for Low Frequency Vibrations

This paper presents a new micro-electromagnetic power generator with a large output power density for the application of low frequency vibrations $(\le 10$ Hz). The 16-poles thin magnet plate $(8.9 \times 8.9 \times \mathrm{t}0.5$ mm) alternately magnetized with a chessboard pattern by laser assisted heating helps enhance the magnetic field to coils. The high-aspect-ratio microarray coil (4 x 6 matrix, coil width: $80 \mu \mathrm{m}$, coil thickness: $160 \mu \mathrm{m}$, total turns: 144/coil unit) fabricated by thick micromolding is beneficial for increasing coil winding density and reducing its resistance. The fabricated prototype is proved to generate 1.63 mV at 10 Hz and 2 mm excitation. This corresponds to a maximum output power of $0.12 \mu \mathrm{W}$ and a maximum power density of $1.03 \mu \mathrm{W} /$cm3.