Fabrication of strain-sensing fibers with silver nanoparticles and reduced graphene oxide via wet spinning

To advance the industrialization of flexible strain sensors, an innovative flexible sensing fiber was developed through a sophisticated wet spinning process. Silver trifluoroacetate and graphene oxide (GO) were combined with thermoplastic polyurethane (TPU) to prepare the fibers via wet spinning. Ascorbic acid was used to<i>in situ</i>reduce the silver trifluoroacetate and graphene oxide within the polyurethane, causing the growth of silver nanoparticles to bond with reduced graphene oxide, forming a dual conductive pathway. This resulted in the creation of silver nanoparticles/reduced graphene oxide/polyurethane fibers (AgNPs-rGO-TPU sensing fibers). The tensile and sensing properties of AgNPs-rGO-TPU sensing fibers under different parameters were investigated. The results showed that with 25 wt% TPU as the matrix, 30 wt% silver trifluoroacetate, and 1 wt% graphene oxide, the fibers achieved an optimal balance of mechanical and sensing properties. The tensile strength was 7.69 MPa, the elongation at break was 370.75%, and the toughness modulus was 18.45 MJ m^-3. The AgNPs-rGO-TPU sensing fibers effectively detect external stimuli, exhibiting high sensitivity over a wide strain range (gauge factor is 4.25 below 5% strain, 24.79 in the 5%-25% strain range, 23.06 in the 25%-80% strain range, and 21.32 in the 80%-110% strain range), with a conductivity of 163.17 ms·cm^-1. They can stably recognize movements and physiological signals from various parts of the human body, showing good application prospects.