Enhancing the Sensing Performance of Chitosan/Chitosan Nanofiber-Based Hydrogel Using Carbonized Crepe Paper

Polysaccharide-containing hydrogels are noted for their adhesion, self-healing, and mechanical properties, yet their sensing performance at low strains needs improvement. This challenge stems from integrating hydrophobic electronic conductive materials to exceed their percolation threshold within hydrophilic polymer networks. To address this, a composite hydrogel was developed using a chitosan (CS)/chitosan nanofiber (CSF) hydrogel encapsulating carbonized crepe paper (CCP), which has a network of interwoven carbonized cellulose fibers. The integration of CCP with the CS/CSF-based hydrogel grants the composite hydrogel satisfactory mechanical properties, adhesion, self-healing capability, and antibacterial properties. As an electronically conductive material with a continuous conductive network, CCP significantly improves the composite hydrogel’s sensitivity, achieving a high gauge factor of 13.3 in the 250–400% strain range. The sensor also shows a low detection limit (0.2%), fast response and recovery times (166 ms), and excellent stability and durability (over 1000 cycles at 10% strain). These features make the composite hydrogel-based strain sensor effective for monitoring human health and activities. Furthermore, soaking in a water-glycerol binary solvent improves the composite-G hydrogel’s water retention and maintains mechanical properties and sensing performance from −18 to 60 °C. This work offers a promising approach for enhancing polysaccharide-based hydrogel sensing performance.