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For decades children – and adults – have cowered behind a cushion when the shape-shifting T-1000 robot assassin hunted Arnold Schwarzenegger in the hit movie Terminator 2.

But the terrifying technology is closer to becoming a reality now that scientists have created a sophisticated form-changing material. that could allow robots to switch between hard and soft shapes.

The material, that could lead to a new generation of droids, is able to morph into different states thanks to its precise mixture of wax and foam.

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The new material (pictured) is made from wax and foam so it can change form easily. The material in on the left, is cool so its wax coating is rigid, while the one on the right does not have a wax coating and collapses under weight. By heating a wax coating, it could be as flexible, and could regain its rigid form again with cooling wax coating, while the one on the right is uncoated and remains compliant (here, it collapses under a wrench)

In the 1991 film, Judgment Day, the shape-shifting T-1000 robotic U.S. agent was made of liquid metal, allowing him to morph into a fluid state and squeeze through tight spaces as well as repairing himself when injured.

It is hoped that the new material, which was developed by Anette Hosoi, a professor of mechanical engineering and applied mathematics at the Massachusetts Institute of Technology, (MIT) could give real robots similar capabilities at a low cost.

Their material could be used to build deformable surgical robots, which would move through the body to reach a particular point without damaging any of the organs or vessels along the way.

Robots built from the material, described in a new paper in the journal Macromolecular Materials and Engineering, could also be used in search-and-rescue operations to squeeze through rubble looking for survivors, Professor Hosoi explained.

In the 1991 film, Judgment Day, the shape-shifting T-1000 robotic U.S. agent (pictured) was made of liquid metal, allowing him to morph into a fluid state and squeeze through tight spaces as well as repairing himself when injured. The new material could facilitate shape-shifting powers in the future

 

SQUISHY ROBOTS! Deformable yet rigid material used for robots

To build a material capable of shifting between squishy and rigid states, the researchers coated a foam lattice structure in wax. They chose foam because it can be squeezed into a small fraction of its normal size, but once released, will bounce back to its original shape.

The wax coating, meanwhile, can change from a hard outer shell to a soft, pliable surface with moderate heating. 

Professor Hosoi said that this could be done by running a wire along each of the coated foam 'struts,' before applying a current to heat up and melt the surrounding wax.

Turning off the current again would allow the material to cool down and return to its rigid state.

In addition to switching the material to its soft state, heating the wax in this way would also repair any damage sustained, she said.

'This material is self-healing. So if you push it too far and fracture the coating, you can heat it and then cool it, and the structure returns to its original configuration,' Professor Hosoi explained.

Here, the 3D-printed soft, flexible scaffold that is coated in wax, is being compressed in a temperature-controlled chamber. Heating a composite where the wax coating has broken can enable the wax to soften and 'heal' to restore its original strength and properties

To build the material, the researchers simply placed the polyurethane foam in a bath of melted wax. They then squeezed the foam to encourage it to soak up the wax, said co-author of the study Nadia Cheng.

'A lot of materials innovation can be very expensive, but in this case you could just buy really low-cost polyurethane foam and some wax from a craft store,' she said.

The wax coating could be replaced by a stronger material, such as solder.

Working with robotics experts, the researchers began looking at 'squishy robots,' which are capable of squeezing through tight spaces and then expanding again, much like octopuses do.

But useful robots need to exert a reasonable amount of force on their surroundings in order to be useful.

Professor Hosoi said: 'You can't just create a bowl of Jell-O, because if the Jell-O has to manipulate an object, it would simply deform without applying significant pressure to the thing it was trying to move.'

'If you're trying to squeeze under a door, for example, you should opt for a soft state, but if you want to pick up a hammer or open a window, you need at least part of the machine to be rigid.'