Galvanic corrosion couple-induced Marangoni flow of liquid metal.

The Marangoni flow of room temperature liquid metal has recently attracted significant attention in developing advanced flexible drivers. However, most of its induction methods are limited to an external electric field. This study disclosed a new Marangoni flow phenomenon of liquid gallium induced by the gallium-copper galvanic corrosion couple. To better understand this effect, the flow field distribution of liquid gallium was modeled and quantitatively calculated. Then, the intrinsic mechanism of this flow phenomenon was interpreted, during which natural convection and temperature gradient were both excluded and the galvanic corrosion couple was identified as the main reason. In addition, this conclusion was further confirmed by combining the experimental measurement of liquid gallium surface potential and the thermocapillary effect. Moreover, the temperature condition was found to be an indirect factor to the Marangoni flow. This finding broadens the classical understanding of liquid metal surface flow, which also suggests a new way for the application of soft machines.