LAUSR

Microcopper particles are introduced to trigger and trace persistent surface convection of eutectic gallium indium (eGaIn) when the liquid-metal is partially immersed in shallow alkaline solution. It is found that the surface convection, which further induces large-scale shape transformation of the liquid-metal body, is driven by the surface-tension imbalance originated from the numerous tiny copper–eGaIn galvanic couples through the electrocapillary mechanism. Meanwhile, the particular configuration of particles binding to the liquid-metal surface and surfing with the flow also enables one to capture the flow patterns and visualize the flow field with the assistance of particle imaging velocimetry technology. This overcomes the difficulties in directly observing and quantifying the dynamic surface-flow behaviors of such nontransparent yet highly reflective liquid-metals. Characteristic flow regimes of the liquid–metal surface convection are revealed and their indications regarding the flow beneath the surface are also made.