Multifunctional cellulose/liquid metal conductive fibers with integrated mechanical, thermal, and conductive properties for smart wearables

Cellulose-based conductive fibers are promising eco-friendly alternatives to synthetic fibers in smart textiles. Although cellulose offers good thermal stability and mechanical strength for daily use, its performance falls short for high-performance apparel. Moreover, it is flammable, and the high hygroscopicity affects the conductivity of cellulose conductive fibers. To address these limitations, this study employed liquid metal (LM) as a multifunctional component to fabricate cellulose/LM composite fibers. Different from blending, a novel wet spinning technique was utilized to produce biphasic side-by-side (SBS) fibers, positioning cellulose and LM on opposite sides, enabling both materials to fully realize their functionalities while complementing each other. The cellulose/LM SBS fibers exhibited excellent tensile strength and elongation at break (up to 225.1 MPa and 12.7%, respectively), outperforming neat cellulose and conventional blend fibers. Individual SBS fibers exhibited conductivity suitable for low-power electronics and maintained conductivity and structural integrity under bending, folding, and humid conditions. Notably, SBS fibers exhibited superior thermal resistance, retaining full tensile strength after 10 min at 200 °C, and 33% at 400 °C while preserving structural integrity. These combined properties underscore the strong potential of cellulose/LM SBS fibers as conductive components in smart sensing applications under extreme environments, such as firefighter gear.