▎ 摘　　要

NOVELTY - Preparing hydrogel flexible strain sensor comprises (i) mixing monomer acrylamide, calcium chloride, sodium caseinate and polydopamine solution and dissolving in deionized water to obtain a mixed solution, where the mass ratio of monomer acrylamide, calcium chloride and sodium caseinate is 400:10-80:50-150, the mass volume ratio of monomer acrylamide and polydopamine solution is 400:100-500 g/ml, and the volume ratio of polydopamine solution and deionized water is 100-500:1500-1900, and (ii) adding chemical crosslinking agent N,N'-methylenebisacrylamide to the mixed solution, after stirring, then adding the single-layer graphene oxide dispersion, and stirring at room temperature to obtain the pre-polymerized solution. USE - The method is useful for preparing hydrogel flexible strain sensor. ADVANTAGE - The sensor: has high stretchability, high sensitivity and adhesion; and can be directly attached to human skin to realize real-time monitoring of small or large human movements. DETAILED DESCRIPTION - Preparing hydrogel flexible strain sensor comprises (i) mixing monomer acrylamide, calcium chloride, sodium caseinate and polydopamine solution and dissolving in deionized water to obtain a mixed solution, where the mass ratio of monomer acrylamide, calcium chloride and sodium caseinate is 400:10-80:50-150, the mass volume ratio of monomer acrylamide and polydopamine solution is 400:100-500 g/ml, and the volume ratio of polydopamine solution and deionized water is 100-500:1500-1900, (ii) adding chemical crosslinking agent N,N'-methylenebisacrylamide to the mixed solution, after stirring, then adding the single-layer graphene oxide dispersion, and stirring at room temperature to obtain the pre-polymerized solution, where the stirring time is 25-40 minutes, the mass ratio of monomer acrylamide and N,N'-methylenebisacrylamide is 400:0.1-0.3, the mass-volume ratio of monomer acrylamide and single-layer graphene oxide dispersion is 400:200 g/ml and the mass concentration of the single-layer graphene oxide dispersion is 2 mg/ml, (iii) adding initiator and catalyst to the pre-polymerization solution, and stirring at room temperature for 1-5 minutes to obtain a polymerization solution, where the mass ratio of monomer acrylamide and initiator is 400:5 and the mass-volume ratio of monomer acrylamide to catalyst is 400:5 g/ml, (iv) injecting the polymerization solution into the reaction mold, and then reacting at 20-60 degrees C for 1-2 hours to obtain a hydrogel, and (v) cleaning and drying the hydrogel, installing conductive copper electrodes, and encapsulating flexible strain sensor. An INDEPENDENT CLAIM is also included for hydrogel flexible strain sensor prepared by the above method.