Mechanically Robust and Anti-Swelling Anisotropic Conductive Hydrogel with Fluorescence for Multifunctional Sensing

The intricate muscle arrangement structure endows the biological tissues with unique mechanical properties. Inspired by that, a mechanically robust and multifunctional anisotropic Polyacrylamide/Sodium alginate/Zirconium ion/Carbon dots (PAM/SA/Zr⁴⁺/CDs, PSZC) hydrogel is developed through the synergistic effect of mechanical-assisted stretching, Zr⁴⁺ metal-coordination and CDs embedding. The resulting hydrogel exhibited an impressive tensile strength of 2.56 MPa and exceptional toughness of 10.10 MJ m⁻³ along the stretching direction, attributing to the oriented alignment of PAM and SA molecular chains induced by mechanical-assisted stretching and metal-coordination. The dense network structure endowed the PSZC hydrogel with excellent anti-swelling performance, achieving a swelling ratio of only 1.7% after being stored in water for 30 days. The presence of Zr⁴⁺ conferred remarkable electrical conductivity of 2.15 S m⁻¹ to the PSZC hydrogel. Furthermore, the integration of carbon dots imparted the PSZC hydrogel fluorescence properties, rendering it visual sensing capabilities. Overall, a straightforward strategy is proposed for fabricating a mechanically robust and multifunctional hydrogel suitable for underwater sensing and visual sensing, offering valuable insights for the development of high-performance underwater sensors.