Co-Doped Hybrid Magneto-Mechano-Electric Generator for Powering Watt-Level IoT Systems

Magneto-mechano-electric (MME) generators, which convert ambient magnetic energy into electricity, show promise as power sources for wireless Internet of Things (IoT) sensors. However, their output power remains insufficient for powering watt-level IoT applications. This study addresses this limitation by co-doping Pb(Mg_1/3Nb_2/3)O₃-Pb(Zr,Ti)O₃ (PMN-PZT) piezoelectric single crystals with manganese (Mn) and lanthanum (La). The piezoelectric cantilevers are constructed using an optimized composition containing 1 mol.% Mn and 0.5 mol.% La, designed to operate d₃₂-mode at a resonance frequency of 60 Hz. The piezoelectric cantilever is combined with an electromagnetic coil to complete the hybrid-MME (H-MME) generator, achieving a total root mean square power of 82.19 mW under a 5-Oe magnetic field. The H-MME generator successfully supplied the watt-level power-consuming smart farm system, which included a power management circuit, camera, microcontroller, and Bluetooth module, to transmit images to a smartphone at intervals of 1 h 30 min. These results demonstrate the potential of co-doped H-MME generators to drive watt-level IoT systems, enabling applications with high-energy demands.