Transparent, Antifreezing, Ionic Conductive Carboxymethyl\nChitosan Hydrogels as Multifunctional Sensors

Abstract

By\na simple strategy of immersion in a CaCl₂ solution,\ncarboxymethyl chitosan hydrogels exhibited ultralow-temperature freezing\nresistance below −50 °C. In addition, the introduction\nof electrolyte ions endowed the hydrogels with electrical conductivity,\nshowing stable and reversible sensitivity to human activity, such\nas finger bending, pressing, and pharyngeal swallowing. The conductive\ncarboxymethyl chitosan hydrogels could even be assembled into a two-dimensional\nintegrated array of contact sensors, which successfully perceived\nthe contour and pressure distribution of an object with a certain\nresolution. These transparent biological-based antifreezing conductive\nhydrogels are promising to find applications in integrated wearable\nsensing devices under extremely low temperature environments.