High strength, antifreeze, and moisturizing conductive hydrogel for human‐motion detection

Nowadays, high performance conductive hydrogels have become excellent materials for the design of smart devices, medical equipment, and flexible wearable devices. However, conductive hydrogels are often hindered by problems such as the poor mechanical property, difficulty in long-term use, and narrow operating temperature range. Thus, a high strength hydrogel that can be used in various temperature environment is desired. Here, conductive composite hydrogels were delicately designed and prepared via in-situ polymerization of conductive polymer PEDOT in Poly(vinyl alcohol) (PVA) aqueous solution and then soaking in polyacrylic acid (PAA) solution and glycerin in two stages. The resultant composite hydrogels exhibited good conductivity (~0.95 S/m), and high mechanical strength (~3.6 MPa). Especially, the hydrogels exhibited great strain-sensitive electric behavior as biosensors to monitor routine movement signals of the human body. Additionally, such composite hydrogel displayed excellent flexibility and responded well to multiple strain and subtle human motions in a low temperature (−25 °C) or after long periods in the air(168 h). Thus, the hydrogels have potential applications in various fields, such as human-computer interaction, intelligent bionic material, and wearable flexible devices.