Enabling Controlled Sliding and Multi‐Modal Sensing in an Anti‐Swelling, Muscle‐Inspired Hydrogel via Multiple Cross‐Linking

The development of hydrogel-based flexible sensors is hindered by their inherent swelling and performance degradation in physiological environments. Inspired by the structure-function integration of natural muscle, a biomimetic multifunctional smart hydrogel with a triple-crosslinking structure via polyvinyl alcohol (PVA) crystalline domains, dynamic borate ester bonds, and high-density hydrogen bonds among phytic acid, PVA, and hydroxypropyl cellulose is designed in this study. The network ensures robust structural integrity and long-term stability while maintaining flexibility, exhibiting a swelling ratio of only 2.5% in simulated body fluid (SBF) after 40 days. Embedded MXene nanosheets serve as nano-reinforcers, electronic conductive pathways, and photothermal converters, enabling near-infrared (NIR)-triggered reversible modulation of lubrication and electrical properties of the hydrogel. The obtained hydrogel demonstrates a stable ultra-low friction over extended friction periods (10 h) and exhibits a unique capability for synchronous monitoring of thermal, mechanical, and frictional stimuli through a single resistance signal. This design provides a promising platform for advanced applications in biomimetic articular cartilage, smart wearable interfaces, and adaptive soft robotics.