Synergistic Regulation of MXene/MgO Dual Fillers for High-Performance PVDF-TrFE Flexible Piezoelectric Sensors Toward Rehabilitation Monitoring

Flexible piezoelectric sensors are highly desirable for kinematic evaluation in home-based rehabilitation; however, conventional piezoelectric sensors often suffer from poor output stability, low sensitivity, and insufficient dynamic response. To address these limitations, this study employs electrospinning technology to synthesize PVDF-TrFE/MXene/MgO composite nanofibers, with PVDF-TrFE serving as the polymer matrix and MXene and MgO acting as dual-functional fillers. Benefiting from the synergistic interplay between MXene and MgO, the crystalline phase structure and interfacial polarization behavior of the composite are effectively modulated, promoting the polar β-phase in PVDF-TrFE and significantly boosting its piezoelectric output. The optimized flexible piezoelectric sensor, after optimization, delivers a maximum output voltage of 26.5 V under a 30 N external force (approximately 4.5 times that of the pristine PVDF-TrFE device) while maintaining stable operation over 5000 cyclic loading tests, along with excellent response and recovery characteristics. Based on robotic multi-joint motion tests serving as a preliminary human-motion surrogate, the as-prepared composite flexible piezoelectric sensor collectively shows considerable promise for wearable motion tracking, home-based rehabilitation evaluation, and intelligent health monitoring.