Design and optimization of MEMS piezoelectric energy harvester for low frequency applications

Abstract

Piezoelectric vibrational energy harvester (PVEH) suits best for harvesting vibrational energy from the environment due to the simplicity in design, operation, and compatibility with the micro electro mechanical system (MEMS) technology. In this work, the effect of geometrical parameters on the performance of an Aluminium Nitride (AlN) based MEMS PVEH is analyzed in detail and optimized for lower resonant frequency and higher output power. Electromechanical modeling and validation are carried out for an energy harvester with various proof mass shapes. The optimized PVEH is having a trapezoidal beam and a triangular-shaped proof mass. The effect of the amount of proof mass coverage on the performance parameters is also analyzed. The least resonant frequency is found for the design in which the proof mass coverage is 57 % of the overall length of the harvester and the power peaks when the proof mass coverage becomes 80 %. The proposed structure generated output power of 0.24 $$\mu$$ W at a resonant frequency of 158.8 Hz when an input acceleration of 0.5 g is applied. Then an array using the proposed structure is simulated and compared to an array of conventional rectangular energy harvesters and it is found that array using the proposed structure provides 1.79 times higher power at a lower resonant frequency than the conventional array.