Ultra-Stretchable, High Resilient, and Degradable Dual Physically Crosslinked Hydrogel for Multifunctional Sensing and Self-Powered Human-Machine Interaction

Abstract

Hydrogels have emerged as promising candidates for flexible strain sensors due to their exceptional versatility, surface conformability, and biocompatibility. However, conventional conductive hydrogels suffer from inadequate resilience and low sensitivity under large deformations, leading to unreliable data acquisition. Inspired by the hierarchical structure of skin, this study develops a dual physically crosslinked hydrogel by combining hydrophobic association and nanocomposite reinforcement, achieving remarkable mechanical properties (strain>1000%, resilience efficiency of 96%) and electrical performance (gauge factor > 3.04). The first physically crosslinked points, formed by polymerization of amphiphilic monomers via hydrophobic association, establishes a flexible skeleton that endows the hydrogel with superior toughness and stretchability. The incorporation of rigid 2D MXene nanosheets creates a secondary physical crosslinking through interfacial interactions between surface functional groups and polymer chains, enhancing mechanical strength and elastic recovery stability. Low-field nuclear magnetic resonance (LF-NMR) and rheological analyses elucidate the evolution of the hierarchical network and energy dissipation mechanisms. Concurrently, abundant free mobile ions (Li⁺, Cl⁻, Na⁺, H⁺) synergize with MXene to establish dual ionic-electronic conduction pathways, enabling high sensitivity and strain responsiveness. The sensor not only detects subtle physiological signals (e.g., cardiac rhythms) but also distinguishes macroscopic human movements (e.g., joint flexion) and identifies tactile inputs (e.g., handwriting patterns). Notably, the hydrogel serves as a flexible triboelectric nanogenerator for real-time self-powered sensing. Furthermore, it exhibits rapid degradability, mitigating environmental concerns. This work proposes a universal strategy to reconcile mechanical robustness, environmental adaptability, and ionic conductivity in wearable electronics through rational design of dual-crosslinked networks and dual-conduction pathways. The proposed material architecture opens new avenues for developing sustainable, high-performance human-interactive systems.