Terminator 2 in 2024: liquid metal and soft robots are here today

Flashback: Robots from the future, known as Terminators, are designed to blend in by looking like humans. But the shape-shifting villain of James Cameron’s action-packed sci-fi sequel Terminator 2: Judgment Day takes things a step further. The sinister T-1000 is made of liquid metal, flowing into shiny silver goo before reforming in a variety of shapes. The deadly droid made of malleable metal can impersonate specific people, ooze between the metal bars of cell doors, and form its hands into deadly blades.

Flashforward to today: Metals which stay fluid at room temperature aren’t a science fiction invention: you probably already know mercury. Caesium, gallium and rubidium also have melting points close to room temperature.

Liquid metals and soft robotics

Scientist Michael Dickey calls gallium “arguably the most interesting element on the periodic table”. Alloys of gallium can be stretched and bent, which means these highly thermally and electrically conductive materials could be perfect for soft circuitry and stretchable electronics. Research is underway to use it for wearable devices, flexible displays or even clothes with implanted circuitry.

Liquid metals are a major part of a growing field called soft robotics. Soft robots are made of flexible materials so the device can adapt its shape or movements. Flexible soft robots could be useful for performing delicate tasks and navigating tight spaces.

They could even operate inside your body, as complex medical implants.

Robots like this could copy the way organic creatures move, wriggling like octopuses and worms – a design philosophy known as biomimicry. Indeed, it was the squishy bottom-feeding sea cucumber that inspired a real-life Terminator 2-style development in early 2023.

Miniature shape-changing robots

Scientists at the Chinese University of Hong Kong showed off miniature robots that could shift between liquid and solid, appearing to melt into a blob and then reform in their original shape. They called it a magnetoactive solid-liquid phase transitional machine, created by embedding magnetic particles in gallium.

These embedded magnetic particles do two things. Firstly, the device can be heated via induction, causing it to melt from solid to liquid. Secondly, they allow the scientists to move the device.

The test robot jumped over gaps, climbed up walls, and even split in half, the two sections working together before reforming. One test seemed directly inspired by a scene in Terminator 2, as a robot shaped like a Lego minifig turns into a silver blob to slip through some bars and reform on the other side.

The researchers demonstrated how shape-changing robots could enter a human stomach to deliver drugs or remove unwanted objects. They could also melt into tight spaces and then stay there, solidifying as a sturdy solder joint on a circuit or replacing screws inside fiddly components.

Soft robotics is still at a relatively early stage and faces various challenges. The structure of flexible robots is relatively weak compared to traditional hard metal structures. There’s also the problem of liquid metal embrittlement when metals like mercury or gallium damage the solid metal they come into contact with – a definite problem in an aeroplane or nuclear reactor, for example.

Will it sell?

There’s enormous potential in soft robotics, with liquid metal-based devices that could be self-healing to prolong their lifespan and make them recyclable for other purposes. Biomedical applications are a big opportunity, with potential for everything from tiny drug-delivering implants to artificial muscle, flexible exoskeletons and even sensor-packed electronic skin. Whether it’s in consumer devices like wearables or in advanced biomedical soft robots inside your body, liquid metal-based innovation could have impressive commercial applications.

Fun fact

Even though gallium will melt in your hand, it doesn’t boil until it reaches 2403°C (4357°F) – the widest liquid range of any element. The fluid nature of liquid metals means they can even be used for printing. Liquid metal printed electronics (LMPE) is a field where particles of these fluid substances can be 3D printed into shapes, or even inkjet printed onto flat surfaces and fabrics.

The James Cameron award for effects innovation

As well as assorted ingenious prosthetics created by effects genius Stan Winston and his team, Terminator 2’s T-1000 was brought to life by groundbreaking computer-generated effects. Visual effects company ILM built on their CG ‘morphing’ in James Cameron’s earlier film The Abyss for the much more complex and varied shots of the shapeshifting Terminator. There are only a few minutes of CG in the whole movie, but it took 35 visual effects artists and $5.5 million to pull it off (winning an Oscar in the process).

Meanwhile, for the gloopy sound effects, sound designer Gary Rydstrom put a microphone in a condom and submerged it in flour and water, as well as throwing around yoghurt and dog food (which earned him not one but two Oscars for T2’s sound).

Verdict

Unlike the villainous T-1000, real-life liquid metal comes from a future that could be much friendlier for humans. If challenges like cost and corrosion can be overcome, liquid metal innovation could be a game-changer.