Nanoconfinement-enabled GO hydrogels via Hummers' method for real-time health monitoring

Traditional hydrogels fail to meet the stringent requirements of flexible electronics and biomedical engineering due to their inherent performance limitations. Herein, graphene oxide (GO) was synthesized via the Hummers' method, and nanoconfinement-enabled GO nanocomposite hydrogels were fabricated by incorporating GO into a borate ester crosslinking network. Dynamic borate bonds synergistically interact with the surface functional groups of GO to enhance the mechanical properties of the hydrogels, while the lamellar structure of GO effectively disperses stress and suppresses crack propagation. The as-fabricated hydrogel exhibits remarkable tensile strength (161 kPa), elongation at break (938%), high self-healing efficiency (89.1% for strength and 83.1% for strain), and superior fatigue resistance (recovery rate >90% after cyclic tensile and compressive tests). The hydrogel-based sensor demonstrates tunable gauge factors (1.7 within the 0-250% strain range and 5.3 within the 250-300% strain range), a rapid response time (240 ms), and stable cyclic performance (1000 consecutive cycles at 150% strain). This sensor can precisely monitor various human movements, including joint motion, finger bending, and vocal cord activity, thereby providing a promising platform for real-time intelligent personal health monitoring.