Magnetic-Lens-Assisted Electrospinning of PVDF-TrFE Nanofibers for High-Performance Self-Powered Flexible Piezoelectric Sensors

Wearable electronics have sparked a surging demand across diverse fields; however, their widespread adoption remains constrained by costly fabrication processes and reliance on external power sources. This study innovatively integrates magnetic lens technology into conventional electrospinning systems, achieving magnetically focused deposition of PVDF-TrFE nanofibers through precise Lorentz force manipulation of the charged jet under tailored magnetic fields. A systematic investigation was conducted to examine the effects of incorporating magnetic lenses (with and without) and varying electrospinning distances (14, 16, 18, and 20 cm) on film properties, resulting in eight distinct nanofiber membranes with gradient characteristics. Characterization via field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed that magnetic-lens-assisted samples exhibited significant morphological and structural optimization, including reduced fiber diameter (decreasing from 1.25 ± 0.38 to 0.82 ± 0.21 μm), improved distribution uniformity (coefficient of variation reduced from 28% to 15%), increased fiber density (rising from 69.5% to 97.4%) and reduced porosity (from 30.5% to 2.6%), increased film thickness (enhanced from 45 ± 5 to 95 ± 8 μm), and elevated β-phase content (rising from 52.3% to 81.7%). Furthermore, the magnetic-lens-assisted sensors demonstrated exceptional performance characteristics, including a 300% enhancement in output voltage (increased from 0.85 to 3.41 V), a 360% improvement in sensitivity (from 12.3 to 56.8 mV/N), excellent linearity (R2 = 0.966), and outstanding durability. Given the extensive adoption of PVDF-TrFE in flexible pressure sensing, wearable electronics, biomedical diagnostics, and soft robotics due to its intrinsic piezoelectric properties, the substantial performance enhancements achieved in this study through magnetic-lens-assisted electrospinning and optimized process parameters further amplify the material's functional utility. This advancement not only enriches the application landscape of PVDF-TrFE-based sensors but also establishes a scalable pathway toward next-generation, high-sensitivity, self-powered sensing technologies.