Design and theoretical investigation of a torsional bistable triboelectric nanogenerator

Abstract

Triboelectric nanogenerator (TENG) has been proven to be a high-efficiency device for converting vibration energy into electrical energy. However, the conventional TENG is unable to harvest energy from torsional vibration. To solve this issue, a torsional bistable triboelectric nanogenerator (TBTENG) is proposed. The essential part of the TBTENG is the S-shaped compliant beam, which enables bistability during torsional vibration. Firstly, the stiffness expression of the S-shaped beams is derived using the energy method, and verified by the finite element analysis (FEA). Then, the mechanical and electrical responses of the TBTENG are obtained by solving the equation of motion, and the unidirectional coupled electromechanical equation, respectively. The numerical simulations of the circuit model are also carried out using MATLAB/SIMULINK to validate the theoretical predictions. The effects of system parameters of the TBTENG on both the dynamic responses and electrical outputs are investigated. Finally, the experiment on the prototype of the TBTENG is conducted to verify the design concept. The results show that the novel bistable structure can drive the system to oscillate with large amplitude, which enables the TBTENG to effectively harvest energy from low-frequency torsional vibration. The peak power reaches the maximum value of 0.7 mW at 4 Hz. Moreover, the bandwidth of harvesting energy from low-frequency torsional vibration can be effectively broadened by enhancing the bistability.