Design, Manufacture And Performance Of MEMS Vibration Energy Harvesters Based On Piezoelectric Effect On Silicon

The MEMS vibration energy harvesters have the characters of small volume, highsensitivity, long life, strong environment adaptation, high energy density a nd efficiency of andenergy conversion and can be achievedby the miniaturization manufacturing.It transformsmechanical vibration energy whichis a common form of energy in nature into electricalenergy and is expected to provide high reliability, long electricity forthe wireless sensornetwork, the micro-system in the field and posting structure,low-power electroniccomponents.The MEMS technology can promote the development of low-carbon economyand clean energy, which has been an important developing direction of intelligent MEMSdevices system. The research on MEMS vibration energy harvester performed great scientificsignificance and development prospects.A d31mode MEMS vibration energy harvesters based on piezoelectric effect with eightcantilever beam-center quality block structurefor low frequency applications whichconvertsenvironment vibration energy into electric energy is designed. The heterogeneous integrationmanufacturing of the PZT piezoelectric sensitive unit is achieved on each cantilever.And the16PZT piezoelectric sensitive unitson each cantilever is connected, which increases theoverall output voltage, electrical conversion efficiency, output power and output powerdensity.It transforms environment vibration into energy, and integrates the advantage ofpiezoelectric and electromagnetic generator,improves the output of voltage and current. It hasthe new four cantilever beam-center quality block structure instead of traditional singlecantilever structure, and the PZT thin film is prepared on each cantilever, which increases thepiezoelectric power generation energy and improves the overall energy density and outputefficiency of the system.At the same time, it has lowfirst-orderresonant frequency and is easyto reach to environmental vibration resonance, which produces high-density electric energy. Itprovides a new idea for the new MEMS devices research.This paper reveals the mechanical and electrical conversion effect mechanism of PZTpiezoelectric materials. The force-electric transformation structural model based onpiezoelectric effect of the eight cantilever beams and center quality block structure isestablished.The mechanical behavior of the eight cantilever beams and center quality block structure is analyzed by using MATLAB software and theoretical calculations. The staticanalysis, modal analysis, harmonic response analysis of the MEMS devices structure by finiteelement analysis software ANSYS14.0is analyzed. The dependency relationship of thedevice structure and the first-orderresonant frequency is revealed. The optimal size s of theMEMS vibration energy harvester structuresare obtained, combining micro-machiningprocess constraints.The heterogeneousintegrationmanufacturing of the3.5μm PZTpiezoelectric thick film is accomplished bythe sol-gel proces.The functional structure of thevibration energy harvesters are fabricated by using MEMS micromachining technology withthe wet etching, magnetron sputtering, dry etching, lithography, lift-off technique and so on.And the integrated manufacturing of the MEMS vibration energy harvesters based onpiezoelectric effect is realized by surface bonding and wire bonding technologies. The outputperformance is evaluated by using vibration testing system which can simulates themechanical vibration of the surrounding environment.The experimental results show that thedevice produced166.4mVP-P/264.00mVP-Pand73.05×10-2nW/71.85×10-2nW with anoptimized resistance load of1.20MΩ/3.00MΩ from1g acceleration at Device A’s/DeviceB’sthe first-order resonant frequency of16Hz/41Hz. The output power density is37.27nW×cm-3/36.66nW×cm-3, and the effective area output power density of PZT cell is30.44nW×cm-2/14.97nW×cm-2.And the research and achievement of MEMS vibration energyharvesters based on piezoelectric effect with low frequency response and high energy outputdensity establishs the theoretical and technical basis on solving the power supply problem ofwireless sensor network nodes.