Build it like an earwig wing

When you marvel over inspirational things in nature, the earwig (Proreus simulans) doesn’t tend to come to mind. A group of engineers and palaeobiologists argues otherwise, however.

Earwigs, they say, have the most compact wing folding of any insect, which gives them unparalleled ground mobility for something that flies.

Recreating this complex folding mechanism in an origami-inspired geometrical method opens up potential applications across different fields of engineering.

The work by researchers from Kyushu University, JT Biohistory Research Hall, the University of Tokyo and Hokkaido University in Japan and Oxford University, UK, is described in a paper in the journal Proceedings of the National Academy of Sciences.

An earwig’s hind wings fold automatically under small leathery forewings when it is not in flight, using a pattern that reduces surface area by 10 to 15 times depending on the species.

With the wings protected and their abdomens fully flexible, the insects then are able to wriggle into the soil and other narrow spaces, as well as use their characteristic rear pincers.

Copying that isn’t easy, however. The geometrical requirements required tomographic imaging of folded hind wings and earwig specimens from Oxford University Museum of Natural History and the Museum of Comparative Zoology at Harvard University, US, provided data to build and test the method.

“The method to design our earwig-inspired fan is based on the flat-foldability in the origami model, a mathematical theorem that explains how crease patterns may be folded to form a flat figure,” says Kyushu’s Kazuya Saito, the paper’s lead author.

“Our earwig fan can be designed using classic drawing techniques, but we have also developed and released software that can automatise the process depending on the application requirements.”

Saito and colleagues predict that their earwig-inspired fan will see multiple applications for folding structures, of variable sizes and materials, into highly compact shapes that can be efficiently transported and deployed.

This may include simple articles such as fans or umbrellas, as well as multiple structures for use in architecture, mechanical engineering, and the aerospace industry, including drone wings, antennae reflectors or energy-absorbing panels.

There’s something there for evolutionary biologists as well.

“The wings of modern earwigs show little variation across their approximately 2000 living species, with shape and folding patterns remaining remarkably stable through evolution because of their specialised function,” says Oxford’s Ricardo Pérez-de la Fuente.

“However, a group of long-extinct insects – the protelytropterans – possessed fan-like wings similar to those of earwigs, but different enough to test the consistency of the new design method. Our work shows how palaeontology can be of interest for practical applications.”

Credit: Kazuya Saito