Flexible hydrogel sensor with excellent antibacterial and low temperature frost resistance

Conductive hydrogels are ideal for preparing wearable sensing devices due to their excellent stretchability and flexibility. However, most hydrogels exhibit poor frost resistance, weak water retention, and lack of biocompatibility and antibacterial properties. In this paper, polyvinyl alcohol (PVA) was used as the skeleton, water, and glycerol formed a binary solvent system, and lithium chloride and polyhexamethylene biguanide hydrochloride (PHMB) were added to the hydrogel system as functional materials. The participation of glycerol not only endowed PVA hydrogels with excellent frost resistance but also formed hydrogen bond interaction with PVA, which improved the mechanical properties of hydrogels. Meanwhile, adding PHMB made hydrogel performs excellent antibacterial properties, effectively killing E. coli (Gram-negative bacteria) and B. subtilis (Gram-positive bacteria). Furthermore, based on the introduction of LiCl, the hydrogel displayed high electrical conductivity. The prepared hydrogel sensor could repeatedly detect and distinguish between various human activities, such as walking, frowning, and speaking. Therefore, prepared multifunctional hydrogels possessed excellent application potential in the medical field, health monitoring, and other fields.