Liquid metal enabled thermal switch for active thermal management

• The higher thermal conductivity and highly efficient heat transfer of liquid metal over magnetic nanofluids. • Magnetically controlled liquid metal thermal switch. • Dual-phase interactions between magnetic responsiveness and metallic fluidity. • The thermal switch achieved a switch ratio of 6.9. The growing heat generation in high-power-density systems, particularly within new energy vehicles and advanced electronics, highlight the importance of thermal management. A major challenge in current thermal management materials/devices lies in the inadequate tunability and structurally intricate designs. In this study, we develop an actively controlled liquid metal (LM)-based thermal switch that eliminates mechanical actuators. By integrating nickel microparticles into gallium-based LM, we leverage dual-phase interactions between magnetic responsiveness and metallic fluidity to establish tunable heat-transfer pathways. Under an applied magnetic fields, the nickel-LM composites spontaneously form transient conductive bridges between heat sources and sinks, enabled by magnetohydrodynamic alignment and interfacial tension modulation. Experimental characterization demonstrates a thermal switching ratio of 6.9. The system achieves an enhancement in effective thermal conductivity compared to that of nonactivated states. This contactless control paradigm provides adaptive thermal regulation for power electronics and energy storage systems that require precision temperature management under transient loads.