Totally dynamically cross-linked dual-network conductive hydrogel with superb and rapid self-healing ability for motion detection sensors

To overcome the status quo of fragile network and single function in the single-network hydrogel, this work designed and fabricated a dual-network O-CMCS (O-carboxymethyl chitosan)/PVA (polyvinyl alcohol) PBOC conductive hydrogel based on two kinds of totally dynamic reversible cross-linking networks. The PBOC conductive hydrogel combined a flexible O-PT (oxidized pectin)/O-CMCS network with a rigid PVA-borax network, and CNTs (carbon nanotubes) were introduced to improve its toughness and conductivity. Its structural characteristics were investigated through Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray diffractometer (XRD), nuclear magnetic resonance (NMR) and other techniques. Its superb and rapid self-healing property was confirmed through dynamic rheological tests, and its electrical property was studied through an electrochemical workstation. The co-existence of the dual networks endowed the PBOC conductive hydrogel with excellent stretchable property (821% of the maximum elongation at break), and it could quickly self-heal within 60 s after being cut due to the intense interaction of totally reversible multiple dynamic bonding. Notably, the PBOC conductive hydrogel strain sensor exhibited high strain sensitivity with GF (gauge factor) of 8.44 at 800% strain and could accurately detect all kinds of human motions (e.g. finger bending, wrist bending and elbow bending, etc.), confirming its tremendous application potential in the field of wearable sensor devices.