Phytic acid and carboxymethyl cellulose synergistically reinforced ionic conductive hydrogels for high-strength and low-swelling flexible sensor applications

Ionic conductive hydrogels have emerged as promising materials for constructing flexible wearable sensors due to their excellent flexibility, conductivity, and strain sensitivity. However, current hydrogel sensors face some important challenges, such as poor mechanical performance, high swelling ratios, and limited functionality, significantly hindering their applications. This study developed a poly(acrylic acid- co -acrylamide) (P(AA- co -AM)) hydrogel that was synergistically reinforced by phytic acid (PA) and carboxymethyl cellulose (CMC) (PAA/AM-PA-C ionic conductive hydrogel). The hydrogel demonstrated a tensile strength of 2.05 MPa and an elongation at break of 1081.93 %, along with good fatigue resistance. Additionally, it showed low swelling ratios in aqueous environments including in seawater, ensuring the hydrogel sensor exhibited exceptional strain-sensing capabilities in various conditions. As a flexible sensor, this hydrogel exhibited excellent sensitivity and stable sensing performance, providing precise and consistent responses to joint motion and speaking. Because of the addition of PA, the hydrogel also showed obvious anti-freezing properties, and can maintain good mechanical properties and sensing properties at −20 °C, broadening its applications in various conditions. In addition, the hydrogel showed remarkable antibacterial properties and biocompatibility, offering new avenues for the development of multifunctional hydrogel-based wearable sensors.