Scientists have developed 3D printing technology to create free-standing structures made of liquid metal at room temperature.
Researchers from North Carolina State University developed multiple techniques for creating the structures, which can be used to connect electronic components in three dimensions.
While it is relatively straightforward to pattern the metal "in plane" – meaning all on the same level – the techniques developed by the team mean these liquid metal structures can also form shapes that reach up or down.
"It's difficult to create structures out of liquids, because liquids want to bead up,” said Dr Michael Dickey, an assistant professor of chemical and biomolecular engineering at NC State and co-author of a paper published online in journal Advanced Materials describing the work.
“But we've found that a liquid metal alloy of gallium and indium reacts to the oxygen in the air at room temperature to form a skin that allows the liquid metal structures to retain their shapes."
One technique developed by the team involves stacking droplets of liquid metal on top of each other. The droplets adhere to one another, but retain their shape – they do not merge into a single, larger droplet.
A video of the process is available on the E&T Magazine Facebook page.
Another technique injects liquid metal into a polymer template so that the metal takes on a specific shape, before the template is then dissolved, leaving the bare, liquid metal in the desired shape.
The researchers also developed techniques for creating liquid metal wires, which retain their shape even when held perpendicular to the substrate.
Dr Dickey's team is currently exploring how to further develop these techniques, as well as how to use them in various electronics applications and in conjunction with established 3D printing technologies.
"I'd also like to note that the work by an undergraduate, Collin Ladd, was indispensable to this project," Dr Dickey said. "He helped develop the concept, and literally created some of this technology out of spare parts he found himself."