Core-Sheath Graphene Yarn Sensors for Versatile Wearable Pressure Monitoring

To address the demand for high-performance flexible pressure sensors in wearable electronics, this study proposes a fabrication method for graphene-wrapped yarn piezoresistive sensors with a core-sheath structure. Using stainless steel sewing thread as the conductive core and graphene-coated conductive nylon monofilament as the functional wrapping layer, the yarn twist parameters (1500-3500 T/m) were optimized through controlled wrapping process to systematically investigate the structure-performance quantitative relationship. Results demonstrate that the 3000 T/m sample exhibits optimal sensitivity in the medium-to-high pressure range (1-25 N; S=0.037/N at 25 N), whereas the 2500 T/m sample achieves significantly enhanced sensitivity in low-pressure regime (<1.0 N; S=9.37/N at 0.05 N), representing a nearly 3-fold improvement over its 1500 T/m counterpart (<1.0 N; S=3.12/N at 0.05 N). Moreover, the sensor demonstrates broad detection range (0.01-25 N), fast response time (0.4 s), and excellent cycling stability (no degradation after 7000 compression cycles). Through embroidery and weaving techniques, we fabricated finger-joint motion-monitoring gloves, plantar pressure-sensing insoles, and a 16×16 sitting posture pressure matrix, validating its multiscale application potential in human motion capture and body pressure monitoring. This work provides a novel strategy for developing highly sensitive and customizable textile-based electronic sensors, advancing the practical implementation of wearable health monitoring technologies.