A suit of armour made from paper sounds about as useful as a chocolate teapot, but it all depends on how you build it. Bin Liu of the University of California, Merced, and his colleagues have developed a precision-folded origami shield that can keep anything inside it safe from being squashed.
The shield is a circle of paper with a hole in the centre, and has been scored with an exact pattern of perforation lines by a laser. The pattern consists of smaller and smaller concentric circles, with each circular strip further divided into triangles. The triangles in adjacent strips lean in opposite directions, creating a network of zigzags from the rim to the centre.
Applying pressure to the edge of the shield makes it begin to fold up along these zigzags. But crucially, the hole in the centre never changes size, meaning anything inside is protected. It works because the size of the folds shrinks incrementally, says Liu. "The closer the adjacent crease lines, the less the change in the shape of the fully folded structure."
It's not the first time researchers have turned to the art of origami for inspiration – NASA is investigating origami-folded solar panels as a way of conveniently packing large power arrays on board rockets, for instance.
Liu, who presented the shields at the American Physical Society meeting in San Antonio, Texas, on 2 March, says the team is still thinking about applications. Because the protection relies on origami, rather than the strength of the material, it should find a number of uses, he says. "We can bring robust structure into light and soft materials."
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