Nacre-inspired Highly Stretchable Piezoresistive Cu-Ag Nanowires/Graphene Synergistic Conductive Network for Strain Sensor and Beyond
Recently, it is highly desirable and remains a challenge to design strain-sensing materials and rational geometric structures, endowing the strain sensors with high sensitivity, large stretchability and broad sensing range simultaneously. Herein, core-shell Cu-Ag nanowires (NWs) with tunable morphology and oxidation-resistance is achieved by effective galvanic replacement reaction between Cu NWs and Ag(NH3)2+ without any additive heating, stirring and reducing agent. When the mass ratio of Cu NWs to AgNO3 is 8:6, Cu-Ag NWs exhibits the best oxidation-resistance and electrical conductivity retention in harsh environments. Nacre-memetic conductive composites are achieved by embedding porous conductive networks composed of Cu-Ag NWs/reduced graphene oxide (rGO) in poly(styrene-block-butadiene-block-styrene) (SBS) matrix, enabling the process to be simple, energy-saving, and scalable. It can detect both tiny and large deformation with a wide sensing range (up to 374% strain), high sensitivity (gauge factor up to 87362), high break elongation (up to 660% strain), and excellent reliability and stability. This successful combination of huge sensing range and high sensitivity is attributed to the high stretchabilty of SBS “mortar”, and the hierarchical architecture and the synergistic effects of sensitive two-dimensional (2D) rGO, and conductive stretchable one-dimensional (1D) Cu-Ag NWs “brick”. Additionally, the composites can be used as patterned conductive interconnects for light-emitting diodes.