Multi-Scale enhanced flexible wearable strain sensors: integration of core-shell PVDF/MWCNTs@PVDF/PTFE nanofibers for superior sensitivity, stability, and thermal performance

Abstract

Wearable flexible strain sensors have demonstrated significant potential for monitoring human motion and health. However, many existing devices are constrained by mechanical durability, sensitivity, and environmental stability, particularly during prolonged use and under extreme conditions. In response to these technological challenges, we designed and fabricated an advanced wearable flexible strain sensor utilizing a novel coaxial nanofiber architecture. The sensor employs a PVDF/MWCNTs@PVDF/PTFE ternary composite structure, with its performance further enhanced by an optimized MWCNTs-coated. The fabricated flexible strain sensor demonstrates outstanding mechanical performance, achieving an exceptional elongation at break of 480% while maintaining a high tensile strength of 6.06 MPa and exhibits thermal stability at temperatures as high as 180 °C. Additionally, it achieves exceptional sensitivity (R2=0.97) and durability, maintaining consistent performance over 40,000 stretching and release cycles. The flexible sensor further exhibits excellent resistance to washing and cutting, retaining functionality after 24 h of water immersion and subsequent structural modifications. In physiological tests, the flexible sensor accurately tracked varying heart rates (70, 90, and 120 beats per min) and detected joint movements, highlighting its potential for real-time health monitoring. The proposed scalable fabrication approach not only ensures excellent structural robustness but also simultaneously improves the sensor’s mechanical durability, sensitivity, and thermal performance, thereby broadening its applicability in next-generation biomedical devices.