Synergistic ionic post-impregnation of ZnSO4 enables high-performance MXene-reinforced hydroxypropyl methylcellulose/polyacrylic acid nacre-inspired hydrogel for strain-temperature dual-mode monitoring

ZnSO 4 post-impregnation enhances both the mechanical and conductive performance of the hydrogel. • The hydrogel delivers 509% tensile strain, 34.9 MPa compressive strength, and 4.67 S·m −1 conductivity. • High sensitivity (2.75 kPa −1 , GF = 2.05) hydrogel sensor enables real-time motion monitoring. • The sensor achieves a high sensitivity (TCR = 2.52% °C −1 ) for real-time body temperature monitoring. • Dual-mode sensing hydrogel promises advances in wearable electronics and smart healthcare. Achieving simultaneous enhancement of mechanical and electrical properties is the key to realizing high-performance conductive nacre-inspired hydrogels. Here a nacre-inspired conductive hydrogel strengthened by ZnSO 4 post-impregnation is reported, in which MXene nanosheets act as bricks embedded in a Hydroxypropyl methylcellulose (HPMC)/Poly(acrylic acid) (PAA) mortar. Zn 2+ ions form coordination bonds at the brick-mortar interface, while SO 4 2− ions promote chain entanglement in the mortar phase via the Hofmeister effect, synergistically enhancing the mechanical properties of the hydrogel. Concurrently, ZnSO 4 introduces additional ionic conduction pathways, which further improves the hydrogel's charge transport capability. This ZnSO 4 post-impregnation strategy leads to a holistic enhancement of the hydrogel's performance. The ZnSO 4 post-impregnated hydrogel exhibits a compressive strength of 34.90 MPa, a conductivity of 4.67 S·m −1 , and a tensile strain of 509%, which are superior to most existing conductive nacre-inspired materials. Furthermore, the well-dispersed MXene nanosheets introduce their intrinsic thermosensitivity into the hydrogel. When assembled into flexible sensors, the hydrogel enables dual-mode monitoring of both human motions (from large-range to subtle movements) and real-time body temperature. This work presents an ionic post-impregnation strategy to design high-performance nacre-inspired hydrogels for wearable sensing applications. A nacre-inspired conductive hydrogel strengthened by ZnSO 4 post-impregnation is reported, in which MXene nanosheets act as bricks embedded in an HPMC/PAA mortar. When assembled into flexible sensors, the hydrogel enables dual-mode monitoring of both human motions (from large-range to subtle movements) and real-time body temperature. Download: Download high-res image (88KB) Download: Download full-size image