Highly stretchable, adhesive and antibacterial double-network hydrogels toward flexible strain sensor

In order to solve the contradiction that the conductivity, tensile properties and antibacterial properties of traditional hydrogels cannot coexist at the same time, multifunctional CMCS/GG/PAM double-network (DN) hydrogels are prepared by introducing carboxymethyl chitosan (CMCS) into gellan gum/polyacrylamide (GG/PAM) double-network (DN) hydrogels. CMCS not only endows hydrogels with good antibacterial properties, but also enhances the interaction between GG and PAM networks. The physically crosslinked GG network and chemically crosslinked PAM network synergistically enhance the mechanical performances of the hydrogel, and the mechanical performances of hydrogel can be controlled by adjusting the dosage of GG and CMCS. The hydrogel can reach a fracture stress of 198.4 kPa and a fracture strain of 797.8%. CMCS/GG/PAM DN hydrogels have good adhesion properties, can be firmly attached to aluminum, titanium, pig skin, stainless steel and other solid surfaces. CMCS/GG/PAM DN hydrogels also have excellent biocompatibility, conductive strain sensitivity with a wide sensing range of 0–350%, short response time of 40 ms, and can monitor human movement state and facial micro-expression in real time, so as to be used as a safe antibacterial flexible sensor for human health monitoring.