Low-temperature tolerant strain sensors based on triple crosslinked organohydrogels with ultrastretchability

Abstract Flexible electronic sensors based on conductive hydrogels have received extensive attention in the field of smart wearable electronics. However, the existing hydrogels usually cannot meet the necessary requirements due to their relatively narrow strain range, and low stability, especially at subzero temperatures. In this study, a xanthan gum-Fe3+/polyacrylamide-glycerol (XG-Fe3+/PAAm-Gl) organohydrogel was prepared via the polymerization in situ and solvent-exchange method. XG was initially used to prepare organohydrogels-based sensors with multiple interactions, including covalent cross-linking interaction, ionic coordination interaction and hydrogen bonds. The prepared organohydrogel possesses excellent mechanical properties, such as, ultrastretchability (~1769%) and high strength (~1.5 MPa). In addition, a water-glycerol binary solvent endows the organohydrogel with excellent long-term anti-drying and anti-freezing capabilities, and it can maintain excellent stretchability (>500%), good conductivity and transparency even at −40 °C. A simple biosensor was fabricated using the XG-Fe3+/PAAm-Gl organohydrogel and was used to monitor the detection of human physiological motions, showing remarkable sensitivity and a wide strain range (5% to 500% strain) under a broad range of temperatures (−40 °C to 25 °C). The XG-Fe3+/PAAm-Gl organohydrogel is expected to meet the requirements of flexible sensors for adaption to many complicated environments.