Hybrid piezoelectric–electromagnetic vibration energy harvester using double orthogonal spiral cantilever structure

This work presents the design, modelling, and experimental investigation of a hybrid vibration energy harvester (HVEH) using double orthogonal spiral cantilever, integrating piezoelectric and electromagnetic transduction mechanisms. A centrally mounted magnetic proof mass oscillates between two stationary coils, while piezoelectric strips bonded at high-strain regions convert structural deformation into electrical energy. The harvester geometry and transduction mechanisms were optimized through numerical analysis and experimentally characterized under harmonic excitation. The performance of the hybrid system is compared with standalone piezoelectric and electromagnetic configurations to evaluate the benefits of combined energy conversion. Under hybrid operation at an excitation amplitude of 0.1 mm and resonant frequency of 18.9 Hz, the piezoelectric and electromagnetic subsystems generated maximum powers of 962 µW and 2624 µW, respectively, resulting in a combined output power of 3.58 mW. The proposed double orthogonal spiral geometry enables efficient low-frequency hybrid energy harvesting and offers significant potential for self-powered sensing applications.