Density Modulated (Co‐W)@Ag Core‐Shell Microspheres as Magnetic Fillers of Liquid Metal E‐GaIn for Soft Intelligent Systems

Through innovative composition and structural design, this study develops core-shell microspheres featuring Co-W alloy cores and Ag shells. Their formation relies on the synergistic effect of solid-liquid interface dewetting, principle of energy minimization, and marangoni effect. These microspheres serve as functional fillers within liquid metal (LM) matrix to create magnetic liquid metal (MLM) with magnetism and enhanced conductivity. We focus on the physical mechanism of density matching, achieved by using high-density W to align the density of Co-W cores with that of liquid Ag. This strategy effectively suppresses the upward buoyancy of cores during spheroidization. Furthermore, finite element simulations elucidate the critical role of the marangoni effect in promoting the formation of this core-shell structure. Experimental results verify that density matching significantly improves the encapsulation quality of Ag shells, thereby endowing the fillers with exceptional resistance against LM corrosion. Finally, the versatility of this MLM is validated across the magnetically actuated liquid-metal soft robot, refreshable liquid-metal blackboard, self-healing circuits, and magnetic liquid-metal strain sensor. These diverse applications underscore the immense potential of MLM as the robust candidate for modern soft intelligent systems.