Abstract
This paper presents a micro-electro-mechanical system (MEMS) piezoelectric power generator array for vibration energy harvesting. A complete design flow of the vibration-based energy harvester using the finite element method (FEM) is proposed. The modal analysis is selected to calculate the resonant frequency of the harvester, and harmonic analysis is performed to investigate the influence of the geometric parameters on the output voltage. Based on simulation results, a MEMS Pb(Zr,Ti)O3 (PZT) cantilever array with an integrated large Si proof mass is designed and fabricated to improve output voltage and power. Test results show that the fabricated generator, with five cantilever beams (with unit dimensions of about 3 × 2.4 × 0.05 mm3) and an individual integrated Si mass dimension of about 8 × 12.4 × 0.5 mm3, produces a output power of 66.75 μW, or a power density of 5.19 μW·mm−3·g−2 with an optimal resistive load of 220 kΩ from 5 m/s2 vibration acceleration at its resonant frequency of 234.5 Hz. In view of high internal impedance characteristic of the PZT generator, an efficient autonomous power conditioning circuit, with the function of impedance matching, energy storage and voltage regulation, is then presented, finding that the efficiency of the energy storage is greatly improved and up to 64.95%. The proposed self-supplied energy generator with power conditioning circuit could provide a very promising complete power supply solution for wireless sensor node loads.
Highlights
The use of wireless sensors and implanted medical electronic systems has developed rapidly in recent years
Over the past two years, some new structures or new piezoelectric materials have been applied in energy harvesters, which attain lower resonant frequency and more output power, but the power conditioning circuit for the improvement of high internal output impedance about piezoelectric energy harvester has rarely been discussed in these references [10,11,12]
At least three conclusions can be reached and summarized as follows: Firstly, most micro-electro-mechanical system (MEMS) vibration energy harvesters usually work under high frequency environment conditions, which limits the scope of application for these devices, because the frequencies of available ambient vibration sources are relatively low
Summary
Key Laboratory for Optoelectronic Technology & Systems, Ministry of Education of China, Chongqing 400044, China. Received: 25 December 2013; in revised form: 21 January 2014 / Accepted: 21 January 2014 /
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