A structure whose internal dimensions remain the same regardless of the external forces applied to it sounds fanciful — but that's exactly what this high-tech piece of origami does.
Created by Bin Liu at the University of California, Merced, this is no normal origami. The doughnut-shaped structure, while made from paper, was scored at high-precision using laser. The result is a circular sheet of paper, perforated along lines defining smaller concentric circles, with each of the resulting sub-doughnuts further sub-divided into triangles.
When the entire structure is squashed, the adjacent rows of triangles lean outwards in opposite directions, creating a zig-zag pattern along the plane of the circle. Crucially, each strip of triangles is incrementally smaller the closer you get to the centre, which allows the structure to neatly deform while the hole at the centre remains the same size.
In theory, an object placed at the centre would remain safe — at least until the whole thing had collapsed down to the size of the inner circle, then things may get messy. But the applications for impact protection are obvious: a large structure of this kind made from conventionally soft or weak material could absorb enough energy to keep its contents safe, while saving weight compared to more traditional impact-resistant constructions. [American Physical Society via New Scientist]