Long time power enhancement of vertical capacitive energy harvester using magnetic repulsive force

We propose a method of enhancing output power by magnetic repulsive force in a vertical capacitive energy harvester using electret. Since electrostatic attraction between dielectric mass and electret plate is reduced by magnetic force, the mass velocity is increased, which leads to the sharp current peak and high output power. The device achieved 30 μW (1.5 times compared to that without magnet), which was kept even after 2 million vibration cycles (31 hour).