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Rainbow-coloured spider has engineering clout


(Credit: Jurgen Otto)
(Credit: Jurgen Otto)

A tiny spider is helping engineers develop new optical technologies that could be used on future space missions.

The rainbow peacock spider is just a few millimetres in size. The males attracts mates with flamboyant courtship displays, aided by an intricate pattern of iridescent colouring on its back.

An international team of biologists, physicists and engineers led by Bor-Kai Hsiung of the Scripps Institution of Oceanography set out to find out how such tiny spiders make their intense rainbows.

They used light and electron microscopy, hyperspectral imaging, imaging scatterometry and optical modelling to investigate and generate hypotheses, and then tested those using nano 3D-printed prototypes.

They discovered that the colours stemmed from specialised abdominal scales on the spiders, which combine a microscopic 3D contour similar to an airfoil with nanoscale diffraction grating structures on their surface.

The interaction between these elements breaks light down into its component wavelengths like a prism, but at a scale that’s impossible with current engineering technology.

"Who knew that such a small critter would create such an intense iridescence using extremely sophisticated mechanisms that will inspire optical engineers," said co-author Dimitri Deheyn.

Radwanul Hasan Siddique, a postdoctoral scholar at Caltech and a co-author of the research said it was fascinating that such structures could outperform human engineering. “Even with high-end fabrication techniques, we could not replicate the exact structures. I wonder how the spiders assemble these fancy structural patterns in the first place,” he said.

Technology inspired by these spider scales could be used to overcome technological hurdles in the manipulation of light, and reduce the size of optical spectrometers which use light to identify materials. These could be used to create wearable chemical detection systems, or instruments for use in space missions.

Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.


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