Boosting biomechanical and wave energy harvesting efficiency through a novel triple hybridization of piezoelectric, electromagnetic, and triboelectric generators

Innovative energy solutions are needed to sustainably power the rapid advancement of smart electronics and sensors. One promising approach to reducing reliance on batteries is to harvest biomechanical energy. This work presents a new hybrid harvester by integrating triple mechanisms for converting biomechanical vibrations and wave energy into electrical energy. The triple hybrid device, in the form of pulley-wheel-guided speed-enhanced (P-WISE) system, is an integrated design with three interacted units, containing a piezoelectric generator (PEG), an electromagnetic generator (EMG), and a triboelectric generator (TENG). Featuring tri-stable nonlinear frequency up-conversion and tri-hybrid working mechanisms, the tri-hybrid device amplifies the functioning of the P-WISE system through inter-well motions, significantly increasing the output than single-mode devices because all three mechanisms are contributing to the power generation under a given mechanical load. The developed energy harvester offers a rational solution for powering wearable electronic equipment with enhanced power generation. The fixed pulley mechanism increases the relative speed between the stator and translator of the EMG and the TENG, simultaneously extending the output frequency of the PEG. These advances make it possible to substantially improve the power output when subjected to broadband and low-frequency biomechanical vibrations and irregular water waves. To assess the effectiveness of the triple hybridized generator, a prototype is manufactured, and the corresponding performance test bench is established. During the shaker test, the triple hybrid device's peak power reached 238.49 mW, corresponding to a normalized power density of 5.80 mW/cm³/g² when exposed to a low excitation level of 1-g acceleration at 5 Hz. The P-WISE system enables the PEG and EMG units to operate at 10 Hz. In the swing motion test, the PEG, EMG, and TENG units produced peak powers of 33.7 mW, 49.7 mW, and 106.8 μW, respectively, when subjected to a 1-Hz swing motion with an excitation angle of 30°. The results demonstrate its remarkable capability in powering electronic devices through harvesting biomechanical and irregular wave energy.