Tough, stretchable and self-healing C-MXenes/PDMS conductive composites as sensitive strain sensors

Due to the good elasticity and stretchability, conductive composites can be widely used as sensitive strain sensors in health monitoring, electronic skin and intelligent robotics. However, the preparation of conductive material that integrates excellent mechanical properties, efficient self-healing properties and sensitive sensing properties remains a challenge. Here, we developed a stable and sensitive self-healing strain sensor based on silicone conductive composites and further evaluated the sensing properties by monitoring the motion of human muscles and joints. Disulfide bonds and multiple hydrogen bonds were introduced into the dynamic silicone supramolecular network through the dehydration reactions of amino groups with carboxyl groups and the addition reactions of amino groups with isocyanate groups. Furthermore, the addition of natural small molecule L-citrulline modified MXenes (C-MXenes) through esterification imparted the material good electrical conductivity. The mechanical strain and stress could reach to 413% and 4.78 MPa, respectively. Due to the dynamic disulfide and multiple hydrogen bonds, the conductive composites could spontaneously achieve self-healing with multiple cycles. Even if the sample was repaired, it could still sense the human motion precisely. Moreover, the material exhibited outstanding sensitive of strain. And the GF (gauge factor) was 3.3821. This excellent performance and simple preparation procedure of silicone conductive composites could be developed as a new generation of wearable sensor devices.