Tough, Self-Healing, and Antimicrobial Hydrogel Sensors Based on Hydrogen-Bonded, Cross-linked Chitosan and MWCNTs

Conductive hydrogels, as a flexible electronic material, have found emerging applications in the fields of wearable devices, health monitoring, and electronic skin. However, the current conductive hydrogels lack antimicrobial properties and excellent mechanical properties, which severely limit their applications in wearable and biological interfaces. Herein, a conductive nanocomposite hydrogel consisting of silver nanowires (AgNWs), carboxylated carbon nanotubes (c-MWCNTs), chitosan (CS), and polyacrylamide (pAAm) was prepared by in situ free-radical polymerization without adding any cross-linking agents. Ingeniously, physical interactions (hydrogen bonding) endow the hydrogels with excellent tensile strength (503.64 kPa), ultrahigh tensile (16,000%), high toughness (22.8 MJ·m–3), and self-healing properties. Remarkably, hydrogels based on AgNWs and CS exhibit excellent antibacterial activity against Staphylococcus aureus, Escherichia coli, and Bacillus subtilis. Simultaneously, under the synergistic effect of AgNWs and c-MWCNTs, the fabricated conductive hydrogel sensor exhibits excellent strain sensitivity (gauge factor = 10.42, up to 900%), high conductivity, and fast response time (200 ms). The c-MWCNTs-AgNWs-based hydrogel sensors can sensitively and stably detect human activities, which show that pAAm/c-MWCNTs@CS-AgNWs hydrogels have great potential in the fields of human activity monitoring, e-skin, and soft electronic devices.