Approaches and developments in MEMS power harvesting generators

This paper presents designs and optimizations for two types of micro electromechanical generators system, first one is the narrow band generators which have a particular resonant frequency the second one is wide band generators (tunable generators) where the resonant frequency can be controlled by adjusting the cantilever length, changing the distance between magnets, and etc. The work and developments done by researchers are presented and for comparison, their results are listed below: The Laser-micro generator was fabricated with a total volume of 1 cm³, output power of ~830 μW, frequencies (60-110) Hz. The output power of the (body-worn) generator was 2-25 μW, volume of 0.25 cm³. The vibration-powered generator for intelligent sensor systems has an overall volume of 0.84 cm³ with an average power of 157 μW when tested on a car engine. One type of Paddle generator produced an output power of 2 mW at a frequency of 9.81 kHz. In the frequency sweeper generator, the device generates 0.4 μW with frequency range of 4.2-5 kHz. For Tunable energy harvesting piezoelectric cantilever generator, a natural frequency was successfully tuned over a frequency range of 22-32 Hz to produce power output of 240-280 μW. The resonant frequency of the vibration-based electromagnetic micro-generator was tuned from 67.6 to 98 Hz to produce a power of 61.6-156.6 μW. The tuning of the wide band generators seemed to be effective.