Synergistic β-Phase Enhancement in PVDF – AlN – Yttrium (PAY) Nanocomposites for Flexible Low-Frequency Biomedical Piezoelectric Energy Harvesting

In this study, a PVDF – AlN – Yttrium (Y3+) tri-composite nanofibrous system was developed through sol – gel-assisted electrospinning to enhance β-phase nucleation and piezoelectric energy conversion. The novelty of the work lies in the complementary use of 10 wt% AlN nanoparticles and 5 wt% Y3 + species within the PVDF matrix, where AlN promotes heterogeneous nucleation and interfacial polarization, while Y3 + induces ion – dipole interactions with – CF2 dipoles. Annealing at 140°C followed by corona poling at 26 kV and 80°C further stabilized the electroactive β-phase. FTIR and XRD analyses confirmed 84.13% β-phase fraction and 72% crystallinity for the optimized PA10%Y5% composition. FESEM observations revealed dense, bead-free, and uniform nanofiber morphology with improved filler dispersion. The optimized nanocomposite exhibited a d33 value of 28 pC/N, dielectric constant of 17, open-circuit AC voltage of 17.6 V, and short-circuit current of ~140 µA, corresponding to a maximum AC power output of ~ 595 µW. After rectification, the device delivered ~11.77 V DC and ~286 µW maximum DC power. The silicone-encapsulated PVDF – AlN – Y3 + nanocomposite demonstrates potential for flexible low-frequency biomedical energy-harvesting applications.