High-strength, anti-freeze, transparent and recyclable composite organohydrogel for flexible strain sensor

Hydrogels have received widespread attention as flexible strain sensors in the fields of human motion detection and health monitoring. However, the presence of large amounts of water in traditional hydrogels leads to poor mechanical properties and low anti-freezing, which severely limits their applications. Herein, a novel PVA/DMSO/CMC/AlCl3/TA/LiCl (PDCATL) composite organo-hydrogel was developed by freeze-thaw and salt solution immersion methods, using polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), aluminum chloride hexahydrate (AlCl3·6H2O) and tannic acid (TA) dissolved in a dimethyl sulfoxide (DMSO)/water binary solvent. The PDCATL organohydrogel exhibited high tensile strength and elongation at break (up to 1.90 MPa and 587%), which can withstand >6000 times its own weight, good anti-freezing and excellent transparency (>90% light transmission). The PDCATL organohydrogel still maintained excellent transparency, flexibility, recyclability and signal sensing capability at low temperatures (−20 °C). The PDCATL organohydrogel also had good strain sensitivity (GF = 1.82) as a wearable strain sensor and can be used to detect motion and physiological activity signals in various parts of the human body. This study will provide a viable avenue for the application of hydrogel sensors in the fields of visual human-computer interaction, wearable sensors, visual optical detection and medical health detection.