Harnessing the Induced Magnetostrictive Effect in Fully Flexible Fiber-Based Magnetoelectric Composites for Improved Stray Magnetic Energy Harvesting

Combining the effects of magnetostrictive and piezoelectric, magneto-mechano-electrical (MME) generators have been developed to accomplish stray magnetic field harvesting for noncontact energy harvesting applications. The highly magnetostrictive interaction boosted the output performance of the MME generator in response to external magnetic stimulation. In this study, MME generators were developed using piezoelectric-ferromagnetic (PVDF/BZT-BCT-ferrite) electrospun fiber-based composites. The autocombustion process was employed to prepare nickel ferrite and cobalt ferrite nanoparticles with average crystallite sizes of 35 and 40 nm, respectively. XRD and FTIR analysis of fiber-based composites revealed a significant increase in the electroactive β-phase due to the electrostatic interaction between the inorganic materials and PVDF. FESEM micrographs demonstrated the formation of homogeneous bead-free fibers, whereas EDS proved the elemental presence of BCT-BZT and ferrite in the composite fibers. We optimized the magnetic field conversion efficiency in the MME generator by varying the magnetostrictive material through direct particle–particle connection in the fiber composite and then layer-by-layer connection. The optimized MME nanogenerator effectively harvests magnetic fields, yielding an output voltage and power density of 6.2 V and 88.7 μW/m², respectively, under an AC magnetic field of 6 Oe at 50 Hz. This represents a significant improvement of 385% compared to conventional generators. This MME device shows great promise for providing substantial power to implantable wireless sensor network devices.