Based on microelectromechanical (MEMS) technology, this paper presents two electromagnetic vibration energy harvesters. We designed and fabricated two models with different vibration structures. As part of the energy harvester, a permanent magnet is attached to a vibration structure (resonator) made from silicon and a very small wire-wound coil. The total volume of the coil is about 0.9 cm3. Tests and comparisons are performed on two energy harvesters with different resonators.
The maximum load voltage of Model A is 143 mV, and, for Model B, it is 196 mV. Model A generated a maximum load power of 51.52 μW across a 405 Ω load at 347 Hz. Model B generated a maximum load power of 135.35 μW at 311.4 Hz with an acceleration of 0.5 g. Compared to Model A, Model B has a higher output voltage and greater working bandwidth. Under similar experimental conditions, Model B's performance is better than Model A's. Using simple analysis, the results indicated that electromagnetic energy harvesting with Model B provided better results. Furthermore, it shows that a non-linear spring might be able to extend the frequency bandwidth and increase the output voltage.
