Design, Manufacturing and Characterization of Stretchable Silicone-Based Conductive Composites

Stretchable conductive composites are important for soft electronics, wearable systems, and adaptive electromechanical devices, yet the mechanisms governing strain-dependent electrical transport remain insufficiently understood, particularly in hybrid filler systems. In this work, the strain-dependent electromechanical behavior of graphite–silicone and hybrid graphite–copper–silicone composites was investigated under uniaxial tensile deformation up to 60% strain. Electrical measurements revealed distinct transport behaviors governed by filler composition and conductive network structure. Graphite-only composites containing 50 wt% and 60 wt% graphite exhibited monotonic resistance increases with increasing strain due to progressive widening of inter-particle tunneling gaps between neighboring graphite platelets. In contrast, hybrid graphite–copper composites showed monotonic resistance decreases under deformation, which is attributed to Poisson-ratio-driven transverse contraction, tunneling-gap reduction, and strain-assisted formation of Cu–Cu and Cu–graphite conductive pathways. Representative volume element (RVE)-based simulations further supported the proposed transport interpretation. From an engineering design perspective, the results show that filler composition and conductive network architecture can be used as design variables to tune strain-dependent electrical responses in stretchable conductive composites. These findings provide design guidance for developing silicone-based conductive composites with tunable electromechanical functionality for soft electronics, wearable sensors, and adaptive devices.