Highly Sensitive and Stable Flexible Sensors Based on Antifreezing\nand Self-Healing Double-Network Composite Hydrogels for Human Motion\nMonitoring

Abstract

Hydrogels\nexhibit ideal flexibility and biocompatibility, which\nhave attracted the attention of many researchers in the field of flexible\nelectronics. However, the challenge exists to endow hydrogel flexible\nsensors with higher strength, stretchability, excellent self-healing\nefficiency, and wide application temperature range. Herein, a stretchable,\nconductive, antifreeze, and self-healing hydrogel was prepared by\nimplanting polyaniline (PANI)-coated cellulose nanocrystals (CNCs)\nand betaine into a gellan gum (GG)/poly­(acrylic acid) (PAA) hybrid\ndouble network. Surprisingly, the fracture stress of the hydrogel\ncould reach 1.51 MPa and the self-healing efficiency improved from\n74.5 to 90.1%, which was attributed to the incorporation of CNCs-PANI.\nMeanwhile, the self-healing efficiency of the hydrogel could reach\n72.8% within 7 h at −30 °C due to the introduction of\nthe antifreeze agent betaine. The assembled hydrogel strain sensor\npossessed high sensitivity (GF = 4.6) within a large strain range\nand output a stable signal even at low temperatures. Overall, the\ndeveloped flexible sensors are able to accurately capture various\nhuman motion signals over a broad temperature range.