Gradient CNT/PMN-PT/PVDF piezoelectric composites for gait monitoring during weight-bearing walking†

Abstract

Wearable piezoelectric sensors have gained significant attention for real-time biomechanical monitoring applications, yet existing designs often suffer from limited sensitivity, durability, and dynamic response. To address these challenges, we develope 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 a poly(vinylidene fluoride) (PVDF) matrix, in which strategically distributed carbon nanotubes (CNTs) and lead magnesium niobate–lead titanate (PMN-PT) ceramic particles synergistically enhance electromechanical coupling efficiency. The CNT-enriched surface layer boosts polarization by enhancing charge injection efficiency, while the gradient-arranged PMN-PT fillers induce stress concentration, further amplifying the sensor's piezoelectric output. As a result, the sensor exhibits exceptional performance, with a decent piezoelectric coefficient and high sensitivity (172 mV N⁻¹). 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.