New and efficient design of multimode piezoelectric vibration energy harvester for MEMS application

The major challenges in a piezoelectric energy harvester (PEH) are high operating frequency, narrow bandwidth and low output generation. We propose a new and efficient design concept based on optimal geometry shape and optimal segmentation of piezoelectric layer at strain nodes of higher vibration modes. The analytical model of the proposed design concept is developed and comparative analysis is performed to compare with conventional rectangular PEH and non-segmented trapezoidal PEH. For a mode 3 harvester design, the simulation result shows that there are three resonant peaks for voltage generation, at the fundamental, 2nd and 3rd resonant frequencies to enable multi-frequency operation that widens the operating frequency range of PEH. The parallel connection of the piezoelectric PZT segments to a common load resistance yields 21.6 mW, 0.23 mW and 0.15 mW power output for three resonant frequencies at 0.5 g input acceleration for optimal load of 21 kΩ. The proposed device shows a performance improvement and reduction in operating resonating frequencies of the higher modes of vibration compared to conventional rectangular and a non-segmented trapezoidal shaped PEH. The harvester provides an alternative to complex and inefficient device design of multimodal energy harvesters.