Ultra‐high stretchability and wide temperature range adhesion hydrogels for flexible sensor

Abstract

AbstractEnsuring adhesion over wide temperature range is of considerable significance for hydrogel‐based wearable sensors, especially in extreme environments. In this research, a hydrogel with adhesive properties over a wide temperature range (−20–80°C) was prepared by copolymerizing 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), acrylic acid (AAc), and sodium lignosulfonate (LS) in binary solvent of H2O and glycerol (Gly). Hence, the hydrogel acquires adhesive properties through the establishment of non‐covalent interactions with the substrate surface, encompassing hydrogen bonding, metal complexation, and electrostatic interactions. At −20°C, ambient temperature (20°C), and 80°C, the hydrogel exhibits significant shear strength of 39.8, 74.3, and 46.9 kPa. In addition, chemical crosslinking points, hydrogen bonding and electrostatic interaction are imparted with good mechanical properties to withstand large tensile and flexible deformation, achieving a fracture stress of 120 kPa and a strain of 14,288%. Furthermore, the hydrogel exhibits outstanding electrical conductivity, reaching up to 1.58 S/m owing to a substantial concentration of free conductive ions. Moreover, this sensor is able to provide a constant and stable change in electrical resistance signal and is used to monitor human movement signals. This makes it possible to employ AAc/AMPS/H2O/Gly/LS hydrogels as wearable flexible sensors in extreme environments.