Design and test of liquid sloshing piezoelectric energy harvester

The energy harvester based on the piezoelectric effect can convert the vibration energy in the environment into electricity to power the network nodes. In order to broaden the effective frequency bandwidth of the piezoelectric energy harvester and reduce the resonant frequency of the system, a liquid slosh-type piezoelectric energy harvester is proposed in this paper. Based on the theory of the piezoelectric effect, the mechanical model and electromechanical coupling model of the piezoelectric energy harvester were established, and the dynamic characteristics of the liquid slosh piezoelectric energy harvester were analyzed. Based on theoretical model and experimental test, the liquid slosh piezoelectric energy harvester is studied. By making a prototype and building a vibration experiment platform, the energy capture characteristics of the piezoelectric energy harvester were tested experimentally. The experimental results show that when the external excitation frequency is close to the first resonant frequency, the maximum output power of the liquid sloshing piezoelectric energy harvester is 0.068 mW, and the optimal matched impedance is 440 kΩ. When the external excitation frequency is close to the second resonant frequency, the maximum output power of the liquid sloshing piezoelectric energy harvester is 0.178 mW, and the optimal matching load resistance is 600 kΩ. Compared with the traditional cantilever beam piezoelectric energy harvester, the liquid slosh piezoelectric energy harvester has a lower resonant frequency and achieves two resonant peaks in the range of 1–20 Hz, which greatly widens the effective frequency bandwidth and improves the energy capture efficiency of the piezoelectric energy harvester.