Bioinspired silk fibroin/poly-acrylic acid high-performance hydrogel sensors with micro-architecture prepared by rapid polymerization via TA-Fe3O4@MXene catalytic system

Hydrogels are ideal for flexible sensors due to their outstanding advantages such as softness, biocompatibility, and unique flexibility. However, the radical polymerization process of hydrogels is usually associated with intensive input of energy. In this study, tannic acid and Fe 3 O 4 nanoparticles were integrated on conductive MXene nanosheets as catalysts to rapidly polymerize to prepare super-stretchable and highly-sensitive Silk Fibroin/Poly-acrylic acid hydrogel sensors. The synergistic effect of TA and Fe 3 O 4 nanoparticles can maintain the dynamic redox cycling between Fe 2+ /Fe 3+ , to enhance the ability of ammonium persulfate to generate free radicals and rapidly forming hydrogel within 5 min. Inspired by the surface morphology of lotus leaves, a biomimetic strategy was employed to construct micro-protrusion structures on the hydrogel surface in order to enhance its sensitivity. The developed sensor showed excellent tensile strain (946 %) and high tensile strength (195 kPa), high sensitivity (GF = 4.05) and stable cycling ability (>100 cycles). The hydrogel sensor demonstrated high linearity (0.99 within the strain range of 150 %–600 %), low detection limit (1 % for strain and 150 Pa for pressure). Moreover, the hydrogel sensor can accurately detect various physiological signals emitted by the human body, making it highly promising for applications as wearable sensors in personalized healthcare.