Normally you can rely on solid objects to hold their shape: aeroplane wings are skinny teardrops, paper is flat and chairs are good for sitting on. But the US air force has found a way to change that. They have made flat surfaces pop into complex 3D shapes when heated – an ability that could find uses in fields from medicine to flight.
"Think of an antenna that changes its radiation properties depending on its shape, or morphing wings where the shape dictates the function," says Taylor Ware at the Wright-Patterson Air Force Base in Ohio. Although confined to the lab for now, the technique has the potential to make shape-shifting objects a part of normal life.
To build their morphing device, the team used a thin film of liquid crystal elastomers – a material made of elastic polymers that also contains a crystal lattice. Polarised laser light then changes the way the units that make up the lattice are aligned. Because the crystal's thermal properties are not the same in all directions, heating the new arrangement makes some parts of the lattice expand and others contract.
Ordering the crystals just so makes different parts expand and contract against each other such that heating a flat sheet to 175 degrees Celsius makes it morph into a predetermined 3D shape that can be 100 times as tall as the film is thick. Ware says there may be other ways to trigger the shape change that are less extreme, although also less effective, including the application of organic solvents, and potentially even water.
Shape-shifting medicine
Ware and his colleagues adapted their process from the way companies make LCD televisions, so it could plausibly be scaled out of the lab and into the real world.
"Large area sheets of these polymers would be quite accessible," he says. "We certainly have interest in bringing this toward some sort of device in the long term."
Ware thinks biomedical applications are likely to be the first out of the gate, perhaps creating easily implantable devices that can be triggered to morph once inside the body. Just as programming pushed applications for computers beyond their mathematical roots, so programmable matter might expand what our stuff can do.
Journal reference: Science, DOI: 10.1126/science.aaa6579
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