Electromechanical Modeling of the Low Frequency MEMS Energy Harvester

An analytical electromechanical model is proposed to predict the deflection, voltage and the power output a proposed low frequency micro harvesting structure. The high natural frequencies of the existing designs of MEMS vibrational energy harvesters are serious drawbacks. A zigzag design is proposed to overcome this limitation. The mode shapes of the free vibration problem are first calculated together with the natural frequencies of the structure. The piezoelectric direct and reverse effect equations together with the electrical equations are used to relate the voltage output of the structure to the base vibrations magnitude and frequency. The closed form solution of the continuous electromechanical vibrations precisely gives the power output as a function of base acceleration spectrum. The usefulness of the design is proved by the significant increase of the power output from the same base accelerations, providing a method of designing a MEMS harvester with low natural frequency.