Researchers have developed the world's first liquid metal lattice, a design that could pave the way for devices that fully heal themselves when damaged.
The team from Bingham University has already built several structures with it, from soccer balls to honeycombs to even a not-at-all creepy hand.
Describing the process in the journal Additive Manufacturing, their take on liquid metal begins with Field's alloy — a kind of metal made from bismuth, indium, and tin that melts at the relatively low temperature of 62 degrees Celsius. That's low enough to melt in hot water. But when the alloy is cooled, it solidifies, becoming as tough as most other metals.
The technique involves 3D-printing a lattice or skeleton for a structure from Field's alloy. Then the lattice is filled with a layer of rubber. Think of it like skin over the bones that protect our own organs. As long as the temperature remains below 62 degrees, the structure stays rigid and intact.
But when the temperature rises above that mark, the Field's alloy does its melting act. The thing is, the rubber layer still keeps everything together — only now, the structure can be bent, shaped and even pressed into a pancake. Let the alloy cool and it hardens again. But the rubber shell pulls the alloy back into its original form.
"Without the shell, it won't work, because the liquid metal will flow away," Zhang explains in a press release. "The shell skeleton controls the overall shape and integrity, so the liquid metal itself can be confined in the channels. We spent over half a year developing this manufacturing process, because this new lattice material is very hard to process. You need to find the best materials and processing parameters."
If you're getting a Terminator vibe here, lead researcher Pu Zhang doesn't blame you. Liquid metal literally came from the future in the 1991 classic sci-fi film.
"To be honest, I've never watched that movie!" Zhang notes in the press release.
This wouldn't be the first time scientists have experimented with liquid metal. Last year, Chinese researchers took an even more direct page from Terminator by demonstrating how highly deformable alloys like gallium can be infused with magnetic particles like nickel and iron to create a liquid metal that can be sculpted with magnets. That research, they noted, could lead to shape-shifting, or soft, robots that, hopefully, won't make war on the human race.
The potential for the new liquid metal lattice, on the other hand, is mostly out of this world. Spacefaring vessels and even satellites don't encounter any wind resistance or atmospheric friction of any kind. So the low melting point of Fields alloy isn't an issue. But they do get banged around a lot.
"A spacecraft may crash if it lands on the moon or Mars with some kind of impact," Zhang explains in the release. "Normally, engineers use aluminium or steel to produce the cushion structures, but after you land on the moon, the metal absorbs the energy and deforms. It's over — you can use it only once.
"Using this Field's alloy, you can crash into it like other metals, but then heat it up later to recover its shape. You can use it over and over again."