Optimization Design, Manufacture And Performance Of MEMS Piezoelectric And Electromagnetic Hybrid Micro-power Devices

The power supply for wireless sensor network nodes is the important factor affecting thedevelopment of wireless sensor networks. As a traditional power supply, the battery with theexistence of large volume, short life and other issues which can not meet the power supplyrequirements of high performance for wireless sensor network nodes. Vibration energyharvesting micro-power devices have the advantages of high energy density, long life,non-pollution, strong environmental adaptability, easier miniaturization. And it is expected toprovide stable, reliable power supply for massive wireless sensor network nodes.In this paper, MEMS vibrational piezoelectric and electromagnetic hybrid micro-powerdevices based on four cantilever beams and center quality block structure are studied. Ittransforms mechanical vibration into energy, and integrates the two energy conversions ofpiezoelectric and electromagnetic power generation which improves the overall outputvoltage of device. The structure of four cantilever beams and center quality block with lowresonant frequency, which is suitable for low-frequency vibration environment. By separatingthe different piezoelectric modal areas on the cantilever beams, each PZT piezoelectricsensitive unit on each cantilever is connected, which increases the piezoelectric power energyoutput and improves the overall energy density and output efficiency. And it expands a newidea for achieving the MEMS micro-power devices with high output energy density.This paper reveals the mechanical and electrical conversion effect of piezoelectricmaterials and the electromagnetic energy conversion mechanism. The structural model ofpiezoelectric and electromagnetic hybrid micro-power devices based on four cantilever beamsand center quality block structure is established. Through analyzing the size parameters ofPZT piezoelectric sensitive unit and induction coil on the output performance of the structure,and combining the MEMS process constraints, the piezoelectric sensitive unit and inductioncoil are optimized, also MEMS machining process and masks of micro-power devices areoptimized designed. The heterogeneous integration of PZT piezoelectric thin film with thethickness of2micrometers and3inches Pt （111）/Ti/SiO₂/Si （100） substrate is achieved bysol-gel technology. The achievement of basic structure with four cantilever beams and centerquality block, machining of induction coil, secondary integration of permanent magnet and basic structure are realized by breaking through micro-nano manufacturing compatibletechnology. Reliable manufacture of MEMS vibrational piezoelectric and electromagnetichybrid micro-power devices based on four cantilever beams and center quality block structureis achieved. The test system is set up. And the output performance of MEMS vibrationalpiezoelectric and electromagnetic hybrid micro-power device is tested and analyzed. Theresults show that the resonant frequency of the micro-power device is8Hz. Open circuitoutput peak-peak voltage of the piezoelectric part is94mV and effective output voltage perunit area of a piezoelectric cell is2.4V/cm², open circuit output peak-peak voltage of theelectromagnetic part is8mV under the acceleration of6g and freguency of8Hz.