High performance hydrogel sensor based on rGO integrated P(AA-HEMA) and starch for motion and temperature monitoring

Smart hydrogel materials demonstrated promising application prospects in flexible electronic devices, human-machine interaction systems, and soft robotics owing to their exceptional electrical conductivity. However, significant technical challenges remained to be addressed for developing multifunctional hydrogel systems integrating both sensing and actuation capabilities. In this study, polydopamine (PDA) was employed to conduct in-situ reduction of graphene oxide (GO) under alkaline conditions, yielding reduced graphene oxide (rGO) with superior electrical conductivity and high photothermal conversion efficiency. The resulting nanomaterial was subsequently combined with natural polysaccharide starch to fabricate a poly (acrylic acid-2-hydroxyethyl methacrylate)/starch/reduced graphene oxide (P(AA-HEMA)/St/rGO) hydrogel composite. This hydrogel system exhibited not only exceptional mechanical properties (176 kPa tensile stress and 1258 % strain) and durability, but also demonstrated high conductivity (3.64 S/m) and sensitive sensing characteristics (achieving a gauge factor of 5.15 at 1300 % strain). The developed hydrogel sensor accurately detected various physiological signals including fist clenching, pulse vibration, and vocalization. Furthermore, by leveraging its excellent photothermal response properties, a three-dimensional array sensor configuration was established, enabling real-time monitoring of ambient temperature variations. Through ingenious material design and structural optimization, this research successfully developed a multifunctional smart hydrogel, providing a novel material solution for biomedical applications and flexible electronic devices.