Liquid metals can spontaneously bulge, protrude, branch and slither in response to certain ions in their environment. This happens due to the Marangoni effect, which starts with uneven changes in the surface tension of a fluid. If researchers can control these movements, they could open up new possibilities for soft electronics and robotics. In a recent report, chemists studied the snake-like locomotion of a gallium-based liquid metal alloy in different solutions containing copper ions.
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Source article:
“Effect of Anions on Deformation of Gallium-Based Liquid Metal in Solution”
Langmuir
Corresponding authors: Bingxing Wang, Ph.D. and Donglin Zhao, Ph.D.
Transcript
Watch this. This liquid metal is moving spontaneously. Researchers call it serpentine locomotion.
It starts with the reaction of gallium in the metal with copper ions in the solution. This reaction creates a coating of copper nanoparticles and lowers the surface tension of the alloy, which means the metal atoms at the surface don’t stick together as tightly.
The first bit of metal starts reacting with the solution right away before the trailing end can catch up. So the surface tension is squeezing it more strongly in some areas than others, and the stuff squishes around. Just like if you squeeze a balloon. The metal keeps squishing until it reaches an equilibrium.
Scientists are studying the ways this alloy responds to different ions in solution to learn how to control its movements. This research could help with the design of soft machines and electronics, but it’s also just very fun to look at.
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