Preparation of silsesquioxane/polyacrylamide/carboxymethyl chitosan hydrogel with ultra-stretchable properties for advanced flexible sensing applications.

The functionalized modification of epoxy silsesquioxane (GSQ) with the sodium salt of glutamic acid was successfully achieved via an epoxy-amine click reaction, resulting in the preparation of sodium carboxylate group-rich Glu-GSQ hybrid nanofillers. These hybrid nanofillers were subsequently incorporated into a hydrogel matrix composed of carboxymethyl chitosan and polyacrylamide, leading to the development of a novel PCH-Glu hybrid hydrogel material with enhanced properties. Remarkably, the optimized PCH-Glu3 hybrid hydrogel exhibits exceptional mechanical properties, demonstrating an ultrahigh fracture elongation of 3528 % coupled with a Young's modulus of 9.57 kPa. Furthermore, the material combines excellent biosafety with notable electrical conductivity (0.39 S/m), making it particularly suitable for strain sensing applications. When fabricated into flexible sensor devices, PCH-Glu3 displays outstanding sensing performance with gauge factors (GF) of 2.68 and 3.63 within the 0-900 % strain range, enabling both wide-range deformation detection and multi-level sensitivity response. In practical applications, the developed sensor demonstrates remarkable capability in precisely monitoring human motion, effectively capturing real-time electrical signal variations associated with diverse physiological movements, including joint motions and subtle facial expressions. These findings highlight the great potential of PCH-Glu3 hydrogel in advanced wearable electronics and human-machine interface technologies.