Constructing stimuli-free self-healing, robust and ultrasensitive biocompatible hydrogel sensors with conductive cellulose nanocrystals

Self-healing conductive hydrogels as artificial skin-like materials hold great potential applications in the fields of artificial intelligence, soft robotics and personal healthcare. However, it remained challenging to construct stimuli-free self-healing biomimetic hydrogels with ultra-stretchability and excellent sensitivity. Herein, polyaniline (PANI) was coated on the surface polycarboxylic multi-branched cellulose nanocrystals (Multi CNC-PANI) via templated polymerization. Afterword, rod-like Multi CNC-PANI served as a dynamic bridge endowed those hydrogels hierarchical structure and dynamic hydrogen bond interactions doped with polyvinyl alcohol (PVA)/borax system. Combined with the dynamic borate ester bonds, the biomimetic nanocomposite hydrogels had high breaking strength (171.52 KPa), ultra-stretchability (1085%), rapid self-healing properties, adhesiveness, decent biocompatibility, and sensitivity. Especially, the hydrogels could keep good self-healing ability both in air and underwater without any stimuli, and the self-healing efficiency could reach up to 99.56% within 120 s. This hydrogel sensor could sensitively detect and distinguish human motions including swallow, fingers, wrist, elbow and knee joints, in real-time. Besides, the self-healed hydrogel gave detective signal with uniform and repeatable sensitivity, which endowed the hydrogels mechanically adaptability and good store stability. Therefore, the strategy may provide unique opportunities in designing biomimetic sensors with skin-like mechanical stretchability, sensitivity and self-healing properties.