Self-healable and conductive mussel inspired PVA/borax@PDA–LiTFSI hydrogel-based self-adhesive for human motion sensor

Conductive hydrogels with adhesive properties have gained substantial attention in recent years due to their potential applications in soft electronics technology and robotic systems. However, fabricating human motion sensor hydrogels with fast self-healing, strong adhesion to human and animal skin, and high conductivity remains a challenge. Herein, a novel strain sensor hydrogel based on polyvinyl alcohol (PVA) and polydopamine (PDA) in the presence of borax as the cross-linker and bis(trifluoromethane)sulfonimide lithium (LiTFSI) as the conductive medium was fabricated. LiTFSI has not been previously applied to PVA/PDA/borax hydrogels for motion sensitivity. The hydrogel demonstrates robust adherence to various substrates, including polypropylene (PP), glass, steel, rubber, human skin, chicken skin, and chicken bone. Notably, the hydrogel exhibited an adhesion strength of 12.4 kPa on chicken skin. The synthesized PVA/borax@PDA–LiTFSI hydrogel exhibits excellent self-healing with fully healed in 30 s. Furthermore, the hydrogel has high conductivity with a value of 0.79 mS/cm. Therefore, the hydrogel is a promising candidate for human motion monitoring and soft robotics applications.