Gradient CNT/PVDF piezoelectric composite with enhanced force-electric coupling for soccer training

Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training, yet existing monitoring systems struggle to reflect specific forces, loci, and durations of action. Here, we design a self-powered piezoelectric sensor constructed by the gradient carbon nanotube/polyvinylidene fluoride (CNT/PVDF) composite to monitor the interactions between the ball and the shoe. Two-dimensional Raman mapping demonstrates the gradient structure of CNT/PVDF prepared by programmable electrospinning combined with a hot pressing. Benefitting from the synergistic effect of local polarization caused by the enrichment of CNT and the reduced diffusion of silver patterns in gradient structure, the as-prepared composite exhibits enhanced force-electric coupling with an excellent sensitivity of 80 mV/N and durability over 15,000 cycles. On this basis, we conformally attach a 3 × 3 sensor array to a soccer shoe, enabling real-time acquisition of kick position and contact force, which could provide quantitative assessment and personalize guidance for the training of soccer players. This self-powered piezoelectric sensor network system offers a promising paradigm for wearable monitoring under strong impact forces.