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• Fabrication of flexible magnetoelectric PVDF/NiFe 2 O 4 nanofiber composite films. • Addition of NiFe 2 O 4 in PVDF plays an important role in transforming α to β phase. • PVDF/NiFe 2 O 4 films exhibit enhanced ferroelectric and magnetic properties. • DC EFM and MFM studies prove the multiferroic nature of the composite films. • PVDF/NiFe 2 O 4 nanogenerator and MME generators, generate a voltage of 10 V and 4.8 V. Flexible nanocomposite films of poly(vinylidene fluoride)(PVDF)/nickel ferrite (NiFe 2 O 4) fiber were made using solvent casting method. The NiFe 2 O 4 fibers with a diameter of 400 nm were synthesized initially by means of electrospinnig technique. Studies of XRD and FTIR confirmed the formation of both α and β phases in the composite films. The presence of α-phase was diminished with the incorporation of NiFe 2 O 4 and a maximum β-phase percentage (68%) was obtained. SEM and AFM analyses also demonstrated the transformation of the microstructures from α to β phase. The ferroelectric properties were tested with respect to NiFe 2 O 4 loading and the composite film with 10 wt% NiFe 2 O 4 exhibited a high P max value of 1.46 μC/cm2. VSM studies revealed the ferrimagnetic behaviour of the films and exhibited a maximum saturation magnetization value of 4.2 emu/cm3. Local ferroelectric properties were investigated through their domain switching behavior using dynamic contact electrostatic force microscopy (DC-EFM), and magnetic force microscopy (MFM) was used to analyze the magnetic properties. The magnetoelectric cross-coupling between ferroelectric and ferrimagnetic orderings is verified through the variations in ferroelectric parameters under different magnetic fields. Then a nanogenerator was fabricated using the composite films and generated an open circuit voltage of 10 V (peak-peak). Additionally, these films were made into magneto-mechano-electric (MME) generator, which could generate a 4.8 V (peak-peak) output voltage under a weak AC magnetic field of 10 Oe at 50 Hz. [ABSTRACT FROM AUTHOR]

The increasing popularity of wearable electronics has sparked interest in flexible energy harvesters as alternatives to conventional batteries. Flexible magnetoelectric (ME) composites, known for converting ambient magnetic field energy into useable power, are emerging as promising autonomous energy sources for integration into wearable devices. In this study, we prepared flexible (PVDF-AlN)–(NiO–CNF) based ME composites using two different methods: solution-casting and electrospinning techniques. The ME coupling was confirmed by measuring the ferroelectric and magnetic properties of the composite, and it was qualitatively characterized through the ME coupling coefficient. The electrospinning fibers-based ME composite exhibited an optimal value of 10.6 V/cm.Oe, significantly higher than the solution-casting films-based ME composite (1.3 V/cm.Oe) under a 1 kHz AC magnetic field (off-resonance condition). Subsequently, a flexible magneto-mechano-electric (MME) generator was designed using electrospun-derived material, harvesting a sinusoidal wave with a maximum output peak-to-peak voltage of 9.02 V. The generator displayed an optimal DC power density of 97 μW/m2 when exposed to a weak AC magnetic field of 6 Oe at a frequency of 50 Hz. Consequently, it holds great promise as an efficient autonomous power supply for medical sensing and various miniature electronic applications. [ABSTRACT FROM AUTHOR]