Plant-Inspired conductive hydrogels with long-lasting stability and low temperature tolerance for flexible sensors and signal transmission carriers

Pliable and conductive hydrogels have been widely studied in soft robots, electronic skin, and artificial sensors. However, their poor water-retention capability and inferior low temperature tolerance make the practical application unrealistic. Inspired by the freezing tolerant plants, a zwitterionic osmolyte (proline) is introduced to the Polyvinylpyrrolidone-Polyacrylamide/Ca-alginate (PACL) hydrogel system through simple solvent displacement strategy. The resulting hydrogel shows excellent stretchability (up to 1226 %), high conductivity (11.96 S/m) and long-term stability. It can successfully remain flexibility and conductivity even at ultra-low temperature (-40 degrees C). The hydrogel-based wearable sensors demonstrate rapid and accurate response to both large-scale movements and subtle motions. Moreover, it can transmit signals as network cables under subzero temperature.