Green and scalable fabrication of self-adhesive PAA-GO@SF hydrogels for multifunctional physiological monitoring and human-machine interaction

Green one-step UV-cured self-adhesive PAA-GO@SF hydrogels without toxic reagents. • Tuning conductive-to-polymer ratio links GO dispersion to hydrogen-bonding network and electromechanical properties. • Balanced performance (GF = 3.68, >1000 cycles, >120 days) enables reliable ECG and HMI applications. Hydrogels are attractive for flexible sensors due to their softness, biocompatibility, and stretchability, but complex fabrication often limits their practical application. Here, we report a self-adhesive sensing hydrogel fabricated via a straightforward one-step ultraviolet-induced copolymerization of polyacrylic acid (PAA) and graphene oxide (GO), with silk fibroin (SF) serving as a biomolecular dispersant and crosslinker to ensure a stable, homogeneous network. The resulting PAA-GO@SF hydrogel delivers a high tensile strength of 120 kPa, a gauge factor (GF) of 3.68, and stable operation over 1000 stretching cycles. In contrast, the same formulation without SF shows a GF of only 1.36, confirming that SF plays a critical role in achieving enhanced sensitivity. The sensing hydrogel enables real-time, high-fidelity detection of physiological signals, including electrocardiogram (ECG) waveforms with clearly distinguishable P-QRS-T (P, QRS, and T waves) features. As a direct benefit for targeted applications, a conformal hydrogel-based sensor array attached to a human hand allows a robotic hand to accurately mimic complex gestures, demonstrating the hydrogel-based sensor's utility in human–machine interaction (HMI). Overall, this work presents a scalable and eco-friendly strategy for multifunctional sensing hydrogel, with clear advantages for electronic skin, motion monitoring, and intelligent robotics.