An ultralow frequency, low intensity, and multidirectional piezoelectric vibration energy harvester using liquid as energy-capturing medium

Abstract

Herein, a piezoelectric vibration energy harvester (PVEH) using liquid as an energy-capturing medium is proposed to simultaneously achieve ultralow frequency, low intensity, and multidirectional vibration energy harvesting in a horizontal plane, which is difficult to realize using traditional PVEHs. The proposed harvester comprises a cylindrical container with a certain liquid, a piezoelectric cantilever beam, ropes, and floater-lever arrays. The experimental results indicate that the proposed harvester with a single floater-lever can generate 9.8 μW under an ultralow frequency (2.6 Hz) and a low intensity vibration excitation (0.03 g), and the normalized power density is 8.89 μW/(cm3 g2 Hz). Under a multidirectional vibration excitation (360° in the horizontal plane) with frequencies below 3 Hz and an acceleration of 0.03 g, the two proposed harvesters with three and four floater-levers indicate a maximum output power (Pmax) deviation of 24.92% and 28.31%, respectively, and an angle bandwidth of 360° (using 2/2Pmax as the standard). All the experimental results indicate that the proposed PVEH is highly promising as an energy supply of wireless sensor networks distributed in ultralow frequency, low intensity, and multidirectional applications.