Liquid metal-based micro/mini-channel heat transfer: Progress, challenges, and opportunities

•1 Liquid metals and their heat-transfer characteristics are introduced.•2 Heat transfer and hydrodynamic characteristics of LMMCHs are reviewed.•3 Actuation techniques of LMMCHs are presented.•4 Fabrication and compatibility of LMMCHs are discussed.•5 Scientific challenges and future directions are discussed. Liquid metal-based micro/mini-channel heat sinks (LMMCHs) are regarded as among the most effective convective techniques for solving high-density heat-transfer challenges in the energy field. LMMCHs offer superior heat transfer capabilities and can operate stably at high temperatures owing to the excellent thermophysical properties of liquid metals and the outstanding convection performance of micro/mini-channel heat sinks. Their thermal performance, actuation techniques, substrate materials, and performance enhancement differ from those of micro/mini-channel heat sinks based on conventional liquids, such as water, alcohol, and oil. Despite their significant potential, to the best of our knowledge, a systematic description of LMMCHs and their progress has not yet been reported. Therefore, in this paper, we present a comprehensive review of liquid metal-based micro/mini-channel heat transfer technology. Specifically, the liquid metals used in micro/mini-channel heat sinks and their thermophysical properties are first introduced. Subsequently, theoretical and experimental studies on LMMCHs are presented and discussed in three aspects: heat transfer and hydrodynamic characteristics, actuation techniques, and fabrication and compatibility. The heat-transfer advantages of LMMCHs are summarized, and the unique actuation techniques and material compatibility are discussed. Finally, scientific and technical challenges are interpreted, and the outlook for LMMCHs is discussed.