A non-resonant type electromagnetic energy harvester for scavenging vibration energy

A new non-resonant electromagnetic energy harvester is presented for improving the energy-scavenging efficiency and the output power. Unlike the conventional energy harvester which uses a permanent magnet attached on a cantilever beam to respond to the vibration, the proposed energy harvester uses a magnet ball located in the cavity of the harvester to respond to the vibration. The ball can move freely in the cavity under the vibration condition and its movement has less dependence on the frequency of the vibration. Moreover, the proposed harvester is very sensitive to the vibration and can obtain an output power (similar to 4.0 mu W) even at a quite low acceleration of 0.02 g. As the acceleration increases to 0.1 g, the output power can be up to 17.7 mu W (power density similar to 2.0 mu W/cm(3)). This harvester is particularly suitable for scavenging vibration energy with wide bandwidth and low acceleration.