Research On Miniature Piezoelectric Vibration Energy Harvesters

Compared with the traditional chemical energy battery,the piezoelectric vibration energy harvester has the advantages of long working life,maintenance-free and pollution-free,and it is an ideal power supply for wireless sensor nodes.Wireless sensor nodes working in a narrow space are sensitive to their working volume and manufacturing costs of the harvester.Therefore,it is of great significance to concentrate on the research of the miniature vibration energy harvester with small size,low cost and strong practicability.A miniature piezoelectric vibration energy harvester was designed to solve the problems that the research threshold of silicon-based micro piezoelectric vibration energy harvester is high and the volume of small piezoelectric vibration energy harvester is relatively large.The structure parameters optimization of the harvester was done by using the distributed parameter model,and a prototype was fabricated mechanically.The self-powered wireless temperature and humidity sensor node based on the miniature piezoelectric vibration energy harvester was designed,and the performance of sensor node and prototype was tested.The main work of this paper is as follows:(1)The parameters such as mass length,electrode length and cantilever width of the miniature piezoelectric vibration energy harvester were optimized based on the distributed parameter model of the cantilever piezoelectric vibration energy harvester,and the effects of the Young’s modulus of piezoelectric layer and mechanical damping ratio on the optimization results were analyzed;(2)A prototype of the miniature piezoelectric vibration energy harvester was fabricated by machining.The plane dimension of the harvester is 9 mm×9 mm,and the net volume is 0.12 cm~3.Under base excitation of 0.3 g at 149 Hz,the output power across a matched resistance of 290 kΩis 34.98μW,and the corresponding normalized output power density is 3.239 m W/cm~3/g~2,which is basically equivalent to the silicon-based miniature piezoelectric vibration energy harvester reported in recent reports;(3)A self-powered wireless temperature and humidity sensor node based on a miniature piezoelectric vibration energy harvester was designed and fabricated.The plane dimension of the node is 3.3 cm×4.25 cm,and the harvester is embedded in the sensor node.Under base excitation of 0.3 g at 149 Hz,temperature and humidity data were measured and sent approximately every 16.5 seconds.