Simulation brings a breakthrough



Researchers at ETH Zurich and Purdue University have been studying the secret of the earwig’s origami-like wings and have created an artificial structure that functions on the same principle. Their paper has just appeared in the journal Science.

To analyse the wing structure and function, the study’s lead author, Jakob Faber from the research group led by André Studart, Professor for Complex Materials at ETH Zurich, in collaboration with Prof. Andres Arrieta of Purdue University performed a computer simulation of the wing’s function.

This showed that if the wing were to operate on the classical origami principle – using rigid, straight folds with an angular sum of 360 degrees at their intersections – the earwig would only be able to fold its wing down to a third of its size. The crucial factor in the design of the insect’s wing is its elastic folds, which can operate either as an extensional or rotational spring.

The wing joints are made from layers of a special elastic biopolymer, resilin, whose arrangement and thickness determines the spring type. In some instances, both extensional and rotational functions are combined in the same joint.

Faber and his colleagues also examined the point in the earwig’s wing that is responsible for stability in both the open and closed state: the central mid-wing joint. At this point, the folds intersect at angles that are incompatible with rigid origami theory. “This point locks the wing in place in both its open and closed state,” Faber stresses.