A multifunctional conductive nanocomposite hydrogel for high-performance strain sensors

Abstract

Conductive hydrogels have attracted the attention of researchers due to their similarity to biological tissues and potential application in flexible wearable electronic devices. However, fabrication of hydrogels with high sensitivity in combination with mechanical stretchability and biocompatibility via a simple method remains a great challenge. Here, a novel multifunctional hydrogel with high tensile properties, self-adhesion, strain sensitivity and conductivity is prepared by introducing tannic acid (TA) coated graphitized carbon nanotubes (CNTs) into the network structure composed of polyacrylic acid (PAA) and carboxymethyl cellulose (CMC). The chemical cross-linking constructed the framework for the network of the hydrogel. The dynamic physical cross-linking of the multiple hydrogen bonding among TA, CMC, and PAA together with the π–π stacking between CNTs could dissipate energy effectively. The hybrid of chemical and physical cross-linking endowed the hydrogel with excellent toughness, high stretchability, and self-adhesion. The strain reached 1385% of its original length and self-adhesion force on the wood can reach 16.65 kPa. When the carbon nanotube content was 0.6 wt%, the conductivity of the hydrogel reached 5.13 S m⁻¹. Furthermore, the resultant hydrogel as a strain sensor to detect various physiological human movements was investigated in detail. The results indicated that the multifunctional hydrogel has high strain sensitivity and fast response ability. Therefore, the resultant hydrogel has potential application as a strain sensor for human movement monitoring.