Bare eutectic gallium-indium alloy (EGaIn), has one of the highest surface tensions of any room temperature liquid. Its extreme surface tension should not allow it to spread, but by growing oxide on the surface of the metal, we can cause the metal to spread, as this video demonstrates. The oxide is grown by applying a voltage across an EGaIn/water interface. When the oxide layer is uniform across the surface, the finger makes a nice stable finger, but when the voltage gets too high, the oxide layer becomes inhomogeneous, leading to a marangoni instability.
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. Any reuse must credit the author(s) and provide a link back to this page.