Enhanced magneto-mechano-electric conversion with an arc-shaped piezoelectric cantilever for wireless sensor networks

Magneto-mechano-electric energy harvester (MME-EH) is one of the prospective candidates for powering autonomous Internet of Things (IoT) sensor networks by converting ambient magnetic noise into electrical energy. However, conventional flat-shaped MME-EHs face challenges in effectively harvesting energy from the axially symmetric magnetic field surrounding long, straight power cables. In this work, we develop an arc-shaped MME-EH fabricated through monolithic bonding of flexible lead-free piezoelectric polyvinylidene fluoride (PVDF) polymer onto arc-shaped Ni cantilevers, with NdFeB magnets attached as proof masses. Theoretical analysis, simulations, and experimental results reveal that the arc-shaped MME-EH exhibits a 74% enhancement in output performance compared to its flat-shaped counterpart. Owing to improved strain distribution and elevated electric potential of the arc-shaped PVDF, the optimized device delivers a stable output voltage of 26.2 V, corresponding to a power density of 57 mW m⁻² under a 7 Oe alternating magnetic field excitation at the 50 Hz target resonance. Furthermore, a prototype PVDF-based MME-EH is showcased as a persistent power supply for a wireless sensor network, highlighting its potential for large-scale IoT applications.