"Two-in-one" High Stretchable Healable WPU Based Conductive Hydrogel for Intelligent Wearable Sensing

In recent years, conductive hydrogel based sensors have been widely used because of their flexibility and convenience, especially in strain sensing, handwriting recognition, object shape recognition and so on. In this research, the conductive hydrogel with “two-in-one” structure was well designed to avoid the agglomeration and leakage of liquid metal by using polyvinylpyrrolidone modified liquid gallium indium alloy/polydopamine composite hydrogel as the top layer and hydrogen bonding crosslinked waterborne polyurethane/poly(vinyl alcohol) composite hydrogel as the bottom layer, respectively. Finally, a hydrogel based sensor with excellent stretchability and sensitivity was successfully obtained. The tensile strength of the prepared composite hydrogel exceeded 2 MPa. The elongation at break could be greater than 500%. The toughness was greatly improved due to the introduction of waterborne polyurethane, which was greater than 7.5 MJ/m3. The GF value of the sensors reached 4.54. More interestingly, the mechanical self-healing ability of composite hydrogel prepared by adding polydopamine, reached about 70% of the original. The hydrogel based sensor was able to use for gesture recognition and controlling the manipulator in human-computer interaction. This research can provide a practical idea to achieve advanced intelligent wearable sensing.