Conductive hydrogels (CHs) have drawn wide attention from the field of flexible sensor for their similarities to tissues, excellent flexibility and good electrical conductivity. However, most of the reported hydrogel-based flexible sensors display the disadvantages of poor tensile strength, low sensitivity and insufficient stability, and most of them are prepared with non-degradable synthetic polymers, which have greatly limited their application. To solve these problems, in this work, we have constructed an agar-based dynamic double cross -linked CH by the dynamic crosslinking between agar and borax via borate bonds and the hydrogen bonds be-tween agar chains. The CH exhibits excellent electrical conductivities, tensile properties and self-healing abilities. A novel two-dimensional material, MXene nanosheet, was introduced to further improve the mechanical prop-erties and ionic conductivity of the CH with its high ionic conductivity and ability to form hydrogen bonds with agar. The obtained Agar/Borax/MXene CH displays the excellent strength and elongation of 129 kPa and 105.1 % and the satisfying ionic conductivity of 8.14 x 10-2 S/cm. The flexible sensor assembled with Agar/Borax hydrogel with 0.15 wt% MXene exhibits a wide strain detection range from 0 to 100 %, high sensitivity (GF approximate to 1.520) and good stability. Our work has provided a novel strategy for the construction of green flexible sensors with good mechanical properties and high sensitivity.
