Flexible piezoelectric sensor based on WO₃@UiO-66-NH₂ heterojunction-modified TPU/PVDF composite film for human health and motion detection

Traditional rigid sensors often lack sufficient flexibility, while pure poly(vinylidene fluoride) (PVDF) piezoelectric materials suffer from limited β-phase content and suboptimal mechanical properties. To address these challenges, we synthesized WO₃@UiO-66-NH₂ heterojunction materials via a hydrothermal method and integrated them with electrospinning technology to fabricate flexible TPU/PVDF composite piezoelectric sensor films. Characterization and performance evaluation identified an optimal PVDF-to-TPU mass ratio of 8:2. Moreover, incorporation of 0.5 wt% WO₃@UiO-66-NH₂ yielded the highest β-phase content in PVDF, along with enhanced dielectric properties, energy storage density, and piezoelectric output. The resulting flexible piezoelectric sensor demonstrates a sensitivity of 1.87 V/N, with response and recovery times of 40 ms and 140 ms, respectively. It reliably monitors diverse human activities and physiological signals, including wrist and knee joint flexion, vocalization, swallowing, respiration, and grasping. Combining excellent flexibility, high sensitivity, and rapid response, this sensor shows considerable promise for applications in human health monitoring and motion detection.