High-Strength, conductive dual-network nanocomposite hydrogel for multi-substrate adhesion and enhanced wearable sensor performance

As a promising functional material, hydrogels have attracted widespread attention in the field of flexible wearable sensors due to their excellent biocompatibility and mechanical strength. However, the concurrent incorporation of robust mechanical properties, self-adhesion, and strain responsiveness into a single hydrogel system remains a formidable task in the field. This study proposes an innovative approach for fabricating a high-strength, stretchable, and self-adhesive polyacrylamide/polyvinyl alcohol dual-network nanocomposite hydrogel to address the demands of high-precision strain sensors. By performing in situ photo-polymerization of acrylamide in a precursor solution containing polyvinyl alcohol and bacterial cellulose, the tensile properties of the material were significantly improved. Additionally, the introduction of sodium chloride enhances the hydrogel's mechanical strength and conductivity via the Hofmeister effect, which greatly enhancing the hydrogel's mechanical and electrical performances. The hydrogel demonstrated a maximum tensile strain at fracture of 1019% and a maximum fracture stress of 406 kPa, with toughness and Young's modulus reaching 2.14 MJ/m3 and 0.981 MPa, respectively, indicating excellent tunable mechanical characteristics. Furthermore, the hydrogel exhibited remarkable adhesion to various substrates, including wood, glass, metal, and skin, demonstrating extensive application potential. The introduction of an ion network ensured stable conductivity and strain sensitivity, enabling the hydrogel to achieve precise monitoring of joint movements across multiple human body parts, as showcase outstanding application prospects in wearable sensor technology.