Tough conductive cellulose organohydrogels with antifreezing capability, strain-sensitivity and for multi-functional sensors

The mechanical strength of traditional hydrogels is weak, and it is easy to freeze and harden below zero to lose the characteristics and conductivity of hydrogels, which seriously limits the application of hydrogels in sensors. To solve this problem, an organic hydrogel was prepared using a simple method. After testing, this organic hydrogel not only has good frost resistance but also has excellent mechanical properties. Cellulose-based hydrogels have received increasing attention as good materials for preparing flexible, wearable sensors due to their good biocompatibility, flexibility, and excellent mechanical strength. We polymerized 4-carboxy benzaldehyde (FBA) and polyvinyl alcohol (PVA) into gels under acid-catalyzed conditions, imparted freeze resistance to the hydrogels by introducing dimethyl sulfoxide (DMSO) into the hydrogels, and added water-soluble cellulose acetate (WSCA) to the hydrogels to enhance the mechanical properties of the hydrogels. The organic hydrogel prepared by this method is more stable than conventional hydrogel in low-temperature environments, even below − 80゜C can still maintain the soft state and good mechanical flexibility of the hydrogel, of which WSCA can enhance the mechanical properties, and the stress of the hydrogel can reach 0.85 MPa when the WSCA content is 2%, which is 2.5 times that of the hydrogel without WSCA. In addition, the prepared hydrogel also has good electrochemical performance, under the condition of − 80゜C, connected to the circuit, the small bulb can still maintain a weak brightness. Moreover, the sensor composed of hydrogels can distinguish vigorous movement and weak movement of the human body, which provides a new idea for the application of hydrogels on the sensor.