Development of high-strength, tough, and self-healing carboxymethyl guar gum-based hydrogels for human motion detection

Abstract

Self-healing hydrogels have attracted intense attention because of their potential applications in ionic strain sensors. However, most self-healing hydrogel sensors exhibit poor mechanical properties due to the inherent compromise between the dynamic interactions for healing and steady interactions for mechanical strength. Here, strong, tough and self-healing ionic conductive hydrogel sensors were prepared based on synergistic multiple noncovalent bonds among carboxymethyl guar gum (CMGG), poly(acrylic acid) (PAA), and ferric metal ions (Fe³⁺) in a covalent polymer network. The incorporated CMGG, mediated by metal–ligand interactions, acts as dynamic cross-linkers, endowing the ionic hydrogels with superior mechanical properties. In addition, the reversible and dynamic nature of the multiple metal–ligand interactions accounts for the good self-recovery capabilities, remarkable mechanical properties, and high self-healing efficiencies. Furthermore, the ionic conductive hydrogels displayed good strain sensitivity with repeatable, reliable, and precise changes of resistance signals. Based on these merits, the hydrogel could be assembled as a flexible strain sensor to monitor and distinguish various human motions. We expect that this facile method of incorporating the biocompatible and biodegradable CMGG for the design of strong, tough, self-healing and ionic conductive hydrogels may have promising potential for flexible strain sensors for human motion monitoring.