The technique is based on the fact that the removable oxide skin of the metal behaves similar to a surfactant, which reduces the surface tension between the fluid and the metal.
An NC State associate professor of chemical and biomolecular engineering, Dr. Michael Dickey, states that this change in surface tension made the liquid metal to spread, similar to a pancake, because of the gravitational force.
The research team demonstrated that when the polarity of the charge applied was changed to negative, the oxide was removed and the original high surface tension got restored. This proved the reversibility of the change in surface tension. The researchers found that changing the voltage in tiny steps could tune the surface tension.
Dickey, further states that the novel technique could be used to control liquid metal movement, that could find applications for completing/breaking circuits, modifying antenna shapes, MEMS, optical and photonic devices and in microfluidic channels.
Shape Reconfigurable Liquid Metal
In early studies, Dickey’s lab had shown a novel technique for 3-D printing of liquid metals, where the liquid metal maintained its shape by using the oxide layer that was formed in air.
This study has been published online in the Proceedings of the National Academy of Sciences.
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