An Omnidirectional, High Power Density Magneto–Mechano–Electric Energy Harvester Using PNN–PZT Piezoceramic Operating in Decoupling Bending Mode

Abstract

Magneo-mechano-electric energy harvesters (MME-EHs) capture stray magnetic and weak vibration energy from power lines and vehicles. However, efficiently harvesting microenergy from randomly oriented stray magnetic fields remains challenging. We propose a novel MME-EH featuring two cross-arranged, piezoceramic-metal laminated beams with tip magnetic masses. Using Pb(Ni_1/3Nb_2/3)O₃-Pb(Zr_0.3Ti_0.7)O₃-LiNbO₃(PNN–PZT–LN) ceramic with a high piezoelectric charge coefficient (e₃₃) and operating in decoupled diagonal symmetric bending modes, this design efficiently harvests omnidirectional stray magnetic energy. The high e₃₃ enables significant output current, while the decoupling design avoids interference between two cross-beams, and diagonal symmetry bending modes with a simple support at the central node can dramatically decrease the clamping energy losses. The portable MME-EH generates a record-high output power of 13.3 mW_avg under a weak 2Oe magnetic field at 50 Hz. More importantly, its output power changes less than 22% as the magnetic field direction varies from 0° to 360°, demonstrating omnidirectional energy-capturing capability. The harvested energy successfully powers a multisensor Internet of Things system for real-time environmental monitoring, highlighting the potential of high e₃₃ materials and decoupling strategies for efficient energy harvesting from weak, randomly oriented stray magnetic fields.