Double-Network Slide-Ring Topological Hydrogel Fibers: Fabrication and Sensor Application

Stretchable conductive hydrogel fibers are crucial for flexible electronics, yet their continuous manufacturing and mechanical adaptability remain challenging, which hinders widespread application. In this work, coordination networks of sodium alginate and slide-ring topological networks have been combined to improve the spinnability and mechanical properties of double-network hydrogel fibers for wearable sensors. The coordination of crosslinked networks of sodium alginate with calcium ions not only helps in the in situ formation of spinning processes with tunable mechanical properties but also results in excellent conductivity of the hydrogel fibers. A slide-ring topological network has been introduced through a polymerizable pseudorotaxane between acrylated β-cyclodextrin and long-chain bile acid guest photopolymerized with acrylamide, improving tensile properties of the polymer. The hybrid crosslinked double-network ensures that the fibers have high dynamic mechanical stability with negligible hysteresis and creep. The fabricated hydrogel fibers show excellent ion conductivity (0.64 S m^-1, 20 °C), transparency, and stretchability (>3000%). Accordingly, strain sensors made from hydrogel fibers accurately capture high-frequency (2 Hz) and high-speed (1.6 cm s^-1) motion, exhibit little drift for 300 stretch-release cycles, and detect repetitive human body movements. This double-network slide-ring topological hydrogel fiber system may provide inspiration for the design of textile-based stretchable electronic devices.