High-performance piezoelectric nanogenerator based on TiO₂/P(VDF-TrFE) nanocomposite films for Biomechanical motion sensing applications

Abstract Piezoelectric nanogenerators (PENGs) based on piezoelectric nanocomposites offer efficient, flexible, and sustainable power solutions for converting ambient mechanical energy into electrical energy. This study focuses on the fabrication and performance optimization of a high-efficiency PENG using TiO₂/P(VDF-TrFE) nanocomposite films prepared via the solution casting method. The fabricated PENG device demonstrated remarkable energy harvesting performance, achieving an open-circuit voltage (V OC ) of 17 V and a short-circuit current (I SC ) of 17 µA under finger tapping, surpassing previous studies. The device exhibited exceptional sensitivity to various biomechanical motions, including finger taps, wrist and elbow bends, foot impacts, and even subtle vocal cord vibrations, underscoring its potential for highly responsive sensors and wearable electronics. It is concluded that the optimised TiO 2 concentration in P(VDF-TrFE) boosts the performance of the PENG. The TiO₂ nanofiller concentration was systematically optimized by analyzing structural, morphological, dielectric, and ferroelectric properties at varying volume percentages (0.5%, 1%, 2%, and 3%). XRD confirmed the anatase phase of TiO₂ and the β-phase in both pure and composite films, while FTIR analysis further revealed a purely β-phase structure without any α-phase content, ensuring superior piezoelectric properties. Ferroelectric measurements indicated that the 0.5% TiO₂/P(VDF-TrFE) film exhibited maximum polarization of 3.2 µC/cm², confirming enhanced β-phase formation critical for high piezoelectric performance. In contrast, higher TiO₂ concentrations disrupted the crystalline chain structure of P(VDF-TrFE), reducing polarization and ferroelectricity, as evident from FESEM analysis. While dielectric permittivity increased with TiO₂ content, the concurrent rise in leakage current diminished the ferroelectric properties. Based on these findings, the 0.5% TiO₂/P(VDF-TrFE) nanocomposite film was identified as the optimal composition for PENG fabrication. This work provides a comprehensive analysis of the piezoelectric properties of TiO₂/P(VDF-TrFE) nanocomposites, along with an in-depth review of previous research in this advancing field of nanocomposite-based biomechanical energy harvesting systems.