Bending-Resistant Intimate 3D Graphene-Metal Heterojunctions for Highly Sensitive and Robust Flexible Sensors

Three-dimensional (3D) graphene offers exceptional electrical and mechanical properties at the material level, yet these advantages are often compromised during system integration due to the lack of a reliable, miniaturizable interfacial method with conventional electronics. In particular, mismatched interfacial properties and the absence of robust interconnection techniques have hindered seamless implementation at the system level, stalling progress toward miniaturization and practical applications. Here, we present a localized interconnection method in which conventional silver nanoparticles (Ag-NPs) ink is deposited into a reservoir-structured metal electrode under a controlled thermal environment, selectively accelerating solvent evaporation to yield high electrical conductivity and mechanical robustness. This approach enables the formation of micrometer-scale interconnections with minimal spreading, while achieving low contact resistance (7.14 Ω), stable impedance (< 10⁵ Hz), and high mechanical durability under repeated bending at a 2 mm radius of curvature, along with excellent environmental stability. Finally, we applied the proposed method to high-performance wearable multi-modal motion sensors and electrochemical biosensors, demonstrating its utility in emerging applications, such as human-robot-interaction and point-of-care diagnostics.