July 10, 2013 at 5:05 PM ET
The brutal liquid metal assassin from "Terminator 2" is impressed indelibly on the memory of any action movie fan. But that shape-shifting chrome T-1000 is just a fantasy, right? Well, yes, but a cool technique of building tiny items with liquid metal is definitely a step in that direction.
It'll be a while before a robot can be created that can be sent back in time, but the researchers at North Carolina State University have found a novel form of 3-D printing that uses a special metal alloy that's totally liquid at room temperature.
The gallium-indium alloy can be squeezed out of a tiny syringe, and when it comes in contact with the air, it instantly develops an oxide "skin" that acts like a bag keeping the rest inside.
"The drops are like miniature water balloons," wrote professor Michael Dickey in an email to NBC News. "Metals have appealing electrical, thermal, and optical properties — so the ability to pattern it in 3D may have other applications that go beyond these."
By stacking the droplets, they can build tiny structures like the Eiffel Tower-esque creation in the video above, or make more complicated shapes by stretching and manipulating those drops. And because it is conductive, it can also be laid down on circuit boards like solder — though it would be more like frosting a cake.
While it's an interesting material and process, it's not quite a miracle (or Terminator) just yet. The gallium-indium alloy is about half the price of silver, and Dickey cautioned that the tiny drops are "probably slightly more fragile than that image might invoke... If you touched the metal itself, it might feel like wet paint."
So using it in a real-world situation would require a stabilizing layer, which Dickey said the team is already looking into. "In our paper we demonstrate wires to connect two LEDs to make stretchable electrical connections. The wires are encased in an elastomer."
And lastly, what's the deal with the antlers being put on the cockroach at the end of the video? Actually, says Dickey, those are antennas:
"It was intended as an inside joke since our group is known for liquid metal antennas. It was a play off that, but I thought it illustrated the idea so clearly we included it."
More technical information can be found in the paper describing the NC State team's work, "3D Printing of Free Standing Liquid Microstructures."
Devin Coldewey is a contributing writer for NBC News Digital. His personal website is coldewey.cc.