Fluid-Dynamics-Engineered Graphene–Liquid Metal Hybrid Nanocomposite Ink for Highly Conductive and Stretchable Wearable Fiber Sensors

Flexible wearable electronics require conductive materials that simultaneously show high electrical performance and mechanical robustness under large deformations; however, the development of these materials is hindered by the intrinsic trade-off between conductivity and stretchability. Herein, we report a graphene–liquid metal–thermoplastic polyurethane hybrid nanocomposite ink that forms a mechanically resilient and highly conductive network. The ink was fabricated via a fluid-dynamics-assisted process, enabling simultaneous graphene exfoliation and uniform dispersion of liquid–metal nanoparticles. Subsequent wet-spinning produced conductive fibers with a continuous and uniformly distributed network. The resulting fibers exhibited high electrical conductivity, high stretchability, and stable performance under repeated tensile and bending deformations, while fiber-based electrochemical Na+ sensors showed high sensitivity, excellent selectivity, a fast response, and long-term stability. Furthermore, textile-integrated sensors combined with a wireless module enabled real-time monitoring of physiological signals in human sweat. This study provides a scalable strategy for the design of multifunctional conductive inks and highlights the potential of hybrid nanocomposites for next-generation wearable electronics and healthcare applications.