Gradient CNT/PMN-PT/PVDF Piezoelectric Composites for Gait Monitoring during Weight-Bearing Walking

Wearable piezoelectric sensors have gained significant attention for real-time biomechanical monitoring, yet existing designs often face limitations in sensitivity, durability, and dynamic response. To address these challenges, we develop a wearable sensor utilizing gradient-architected CNT/PMN-PT/PVDF piezoelectric composites for continuous gait monitoring during weight-bearing walking. The sensor features a dual-filler gradient configuration within the poly(vinylidene fluoride) (PVDF) matrix, where strategically distributed carbon nanotubes (CNTs) and lead magnesium niobate-lead titanate (PMN-PT) ceramic particles synergistically enhance electromechanical coupling efficiency. The CNTs-enriched surface layer boosts polarization by facilitating charge injection efficiency, while the gradient-arranged PMN-PT fillers induce stress concentration, further amplifying the piezoelectric output. As a result, the sensor exhibits exceptional performance, with a decent piezoelectric coefficient (d33* = 40 pm/V) and high sensitivity (172 mV/N). Both experimental tests and finite element simulations validate the superior performance of this gradient structure, making it highly effective for real-time kinematic monitoring during weight-bearing walking. This composite-based sensor represents a promising advancement in wearable health technology, with immediate applications in clinical gait analysis, rehabilitation monitoring and sports injury prevention.