Study and Design of MEMS Cross-Shaped Piezoelectric Vibration Energy Harvesters

In this paper, a study and design of a cross-shaped piezoelectric vibration energy harvester is presented. The resonance frequency of the harvesters dictates the applications where they can be used, and more importantly their effects on the power outputs. The variations of the resonant frequencies of T-shaped and cross-shaped harvesters has been studied as a function of their geometry. Different geometrical dimension ratios have significant impact on the resonance frequency, e.g., beam to mass lengths, and beam to mass widths. Accordingly, two cross-shaped piezoelectric energy harvesters featuring a central mass with four beams have been designed operating at resonance frequencies of about 9.8 and 4.3 kHz respectively. The extra mass added to the later design increases the average strain resulting in an improved performance. A cross-coupled rectifier circuit has been designed and simulated in 0.13 mu m CMOS technology to be combined with the harvester to attain an integrated microsystem.