Composition-dependent structural evolution of ternary CB/Ga/Silicone composites for synergistic sensing and comprehensive EMI shielding

• Developed CB/Ga/silicone composites with composition-dependent star-like Ga microstructures. • Achieved tunable strain sensing and frequency-selective EMI absorption via Ga network evolution. • Synergistic CB-Ga conduction enhanced conductivity, EMI shielding, and mechanical stability. This study introduces a ternary composite system based on silicone, carbon black (CB), and liquid metal (LM) gallium. Despite extensive studies on LM/elastomer systems, most have primarily focused on mechanical reinforcement or thermal conductivity, while a systematic understanding of their electrical modeling and electromagnetic shielding performance remains insufficient. Therefore, we utilized silicone as an elastomeric matrix, CB as conductive nanofillers, and gallium as a conductive metallic phase, a flexible composite with enhanced multifunctional performance is realized. Shear dispersion during fabrication induces a unique star-like architecture of gallium, which, together with the conductive CB network, facilitates the formation of efficient and continuous electrical pathways. The resulting composites exhibit notable improvements in mechanical strength, strain-dependent resistive response, and electromagnetic interference (EMI) shielding capabilities. In particular, the optimized composite achieves an EMI shielding effectiveness of ∼35 dB in the X-band, while maintaining stable strain sensing performance over 1000 cycles at 30 % strain. A systematic investigation into the influence of gallium concentration elucidates the correlation between microstructural evolution and the composite’s physical and electromagnetic behavior. This work not only deepens the understanding of LM-based ternary composites but also highlights their potential for advanced applications in flexible sensing, wearable electronics, and EMI attenuation technologies.