Liquid Metal Robots From Our Nightmares Could Also Save Lives

Robert Patrick as the liquid metal T-1000 in Terminator 2: Judgement Day.
Video screenshot by CNET

Scientists have created a tiny robotic system that can transition from solid to liquid form and back again, finally bringing a bit of classic sci-fi lore into reality.

It’s been 30 years since killer liquid metal robots entered our nightmares courtesy of 1991’s Terminator 2: Judgment Day. That movie’s shape-shifting T-1000 robot could seemingly overcome any obstacle while turning parts of itself into weapons at will. 

The specter of Skynet and the robot apocalypse have haunted us ever since, and now an international team of researchers has finally given us a real-world version of a T-1000, although with more altruistic aims. 

The team says it was inspired not by Hollywood, but by the humble sea cucumber, which can transition between soft and rigid body states. 

“Giving robots the ability to switch between liquid and solid states endows them with more functionality,” says Chengfeng Pan, an engineer at The Chinese University of Hong Kong who led the study.

As if to gesture at Terminator-inspired night terrors, Pan and colleagues demonstrate this increased functionality by placing one of their miniature robots in a simulated jail cell and showing how it might escape. 

It can be a little tough to see what’s going on in the video above, but basically the robot melts itself down to a liquid, flows between the bars and into a waiting mold where it cools, reforms itself and then pops back up. Granted, this escapee is a little less terrifying than a T-1000 since it needs a mold at the ready in order to reconstitute itself, but it’s still enough to agitate any Luddite. 

The demonstration is part of a study published Wednesday in the journal Matter. 

Senior author Carmel Majidi from Carnegie Mellon University said magnets make all of this futuristic phase transitioning possible.

“The magnetic particles here have two roles… One is that they make the material responsive to an alternating magnetic field, so you can, through induction, heat up the material and cause the phase change. But the magnetic particles also give the robots mobility and the ability to move in response to the magnetic field.”

The particles are embedded in gallium, which is a metal with a very low melting point of just 86 degrees Fahrenheit (about 30 Celsius), creating a substance that flows more like water than other phase-changing materials, which are more viscous. 

In tests, the mini robots were able to jump over obstacles, scale walls, split in half and re-merge all while being magnetically controlled. 

“Now, we’re pushing this material system in more practical ways to solve some very specific medical and engineering problems,” said Pan.

In other demonstrations, the robots were used to solder circuits, to deliver medication and clear a foreign object from a model stomach. 

The researchers envision the system being able to conduct repairs in hard-to-reach spaces and serving as a “universal screw,” which melts into a screw socket and solidifies with no actual screwing required. 

The team is particularly excited about the potential medical uses. 

“Future work should further explore how these robots could be used within a biomedical context,” said Majidi. “What we’re showing are just one-off demonstrations, proofs of concept, but much more study will be required to delve into how this could actually be used for drug delivery or for removing foreign objects.”

Hopefully the list of foreign objects that need removal won’t ever include weaponized miniature melting robots, as they might prove difficult to track down and extract.