3D printing of flexible sensors based on polyvinyl alcohol/carboxylated chitosan/sodium alginate/silver nanowire high-strength hydrogels

Stretchable polyvinyl alcohol (PVA)/carboxylated chitosan (CCS)-based double network (DN) hydrogels have great potential for applications in soft materials. In this experiment, a leather-like gel with excellent mechanical properties, frost resistance, electrical conductivity, and recyclability was prepared by a one-pot method. The dermal-mimicking network was driven by hydrogen bonding between PVA, alginate, and glycerol (Gly), which enables the gel to exhibit excellent mechanical properties. In addition, the hydrogel can be fabricated into complex structures by 3D printing, cooling molding, and freeze-thaw cycles. 3D printed flexible sensors are suitable for making biosensors to monitor human movements such as fingers, arms, wrists and pulse signals, and can also detect NH3 (50–800 ppm) gas. The overall signal response remained stable after more than 300 cyclic stretching cycles at 100 % strain. This strategy can be extended to construct other multifunctional sensors with high mechanical properties, which have great application potential in the field of flexible electronics.