Study On Micro Piezoelectric Energy Harvester With Multi Secondary Beam

Since entering the21st century, with the development of micro/nano machining technology, micro devices have sprung up in great quantities. Among of the various energy harvesting technologies, the piezoelectric energy harvester has emerged as a prominent research area and continues to grow at a rapid pace. The key technology of piezoelectric energy harvester is how to improve the output power, miniaturized the structure, and minimize the cost. The structure of energy harvester have a significant influence on the performance of the energy harvester. Therefore, It becomes one of the research focus to find a new type structure to improve the performance of the piezoelectric energy harvester.In this paper, the research mainly focus on micro piezoelectric energy harvester with multi secondary beam. Every cantilever is based on Pb (Zr0.53Ti0.47)03(PZT) thin-film. Modal simulation analysis of the micro piezoelectric energy harvester with multi secondary beam is done by ABAQUS6.5software. The PZT thin films were deposited in Pt/Ti/SiO2/Si substrate by sol-gel method and the micro energy harvesters were designed and investigated. The qualities of PZT thin film and the output of micro piezoelectric energy harvester were tested in this paper.According to X-ray diffraction (XRD) analysis, better crystallization was obtained from the PZT thin film. The morphology of PZT thin film was tested by the atomic force microscope (AFM) surface. The average grain diameter of PZT thin film is84.11nm, and the average height is only2.45nm. The leakage current of PZT thin films was measured by the four probe semiconductor parameter analyzer, which is very weak, and the maximum value is4.00E-9A. The dielectric properties of the PZT thin film was tested in the frequency range of50～104Hz by the LCR tester. The capacitance value is maintained between14nF～16nF. The dielectric loss coefficient is never exceeded5%of the total energy. The dielectric constant fluctuations is in the range of2015～2352. The residual polarization (Pr=37.037μC/cm2) and the coercive field (Ec=27.083KV/cm) were obtained by ferroelectric performance test of the PZT thin film. The resonant frequency was obtained by analyzing the output characteristics of the micro piezoelectric energy harvester with multi secondary beam. The first-order resonant frequency is1183Hz and the second-order resonant frequency is2020Hz. At the same position with same size, the output voltage of one beam can reach19.2mV in the micro piezoelectric energy harvester with multi secondary beam, which is far greater than the output voltage (6.4mV) in the single-beam micro piezoelectric energy harvester.