Controlling the surface tension of liquid metals by applying a very low voltage, is now possible thanks to work by a team at North Carolina State University. The research could lead to a new generation of reconfigurable electronic circuits, antennae and other technologies, although worries about a shape-shifting, time-traveling metal Terminator-1000 of movie science fiction fame is probably still a few decades away, to say the least. The researchers used a liquid metal alloy of gallium and indium which normally has a remarkably high surface tension of about 500 millinewtons per meter, this causes the alloy to form spherical beads. When Michael Dickey and colleagues applied a positive charge at less than 1 volt, however, an electrochemical reaction creates an oxide layer on the surface of the alloy, that causes the surface tension to plummet to just 2 mN/m. "We can use this technique to control the movement of liquid metals, allowing us to change the shape of antennas and complete or break circuits," says Dickey. "It could also be used in microfluidic channels, MEMS, or photonic and optical devices."
Moulding liquid metals