Tunable conductivity and porosity in nanocomposite fibers for multimodal wearable sensing

Flexible electronic fibers that combine scalable manufacturability with multimodal physiological sensing remain challenging due to the conflicting requirements of conductivity, porosity, mechanical compliance, and environmental robustness. Here an in-situ thermally induced phase separation (TIPS) strategy integrated into thermal fiber drawing (TFD) was proposed to produce continuous flexible and stretchable porous graphene-polymer nanocomposite fibers with independently tunable pore architecture and electrical properties. Starting from a solvent-borne graphene/polyvinylidene fluoride slurry within an elastomeric cladding, our process yields tens of meters of fiber from a compact preform while accommodating high graphene loadings, enabling a percolated conductive network embedded in a phase-separated matrix. The fiber exhibited a conductivity of (1.35 ± 0.96) × 10− 3 S m− 1, reflecting a moderately percolated network formed within the polymeric matrix that balances electrical transport and structural porosity. The resulting fibers operate as multimodal wearable sensors, namely, a temperature sensor with a stable output and high temperature sensitivity with a negative temperature coefficient of resistance (TCR = 0.558 °C− 1), a pressure sensor with reliable cyclic response, and a dry-electrode cardiovascular data monitoring interface whose impedance/phase behavior closely matches commercial electrodes at low frequencies and captures fundamental features on human skin. The removable elastomeric cladding imparting water resistance supports textile integration and stable operation under humid exposure. This single-step, generalizable manufacturing route decouples porosity and conductivity to co-design fiber mechanics and device performance, advancing scalable fiber-/textile-grade platforms for continuous health and motion monitoring.