Shape-Reconfigurable Liquid Metal Via Surface Oxidation
Liquid metals have large surface tension and therefore typically adopt a spherical shape. Surfactants, like soap, can lower the interfacial tension between two dissimilar liquids - for example, water and oil - but have negligible impact on the large interfacial tensions of liquid metal. North Carolina State University researchers have have developed a new method to control the interfacial energy of a liquid metal via electrochemical deposition (or removal) of an oxide layer on its surface using around one volt. This approach can tune the interfacial tension of a metal significantly, rapidly, and reversibly using only modest voltages. This discovery could enable shape-reconfigurable metallic components in electronic, electromagnetic, and microfluidic devices without the use of toxic mercury. The results also suggest that oxides - which are ubiquitous on most metals and semiconductors - may be harnessed to lower interfacial energy between dissimilar materials.