Squid change color like nobody’s business – can biomimicry help engineers do the same?

  • Red, yellow, and brown Chromatophores (inset) are isolated from a squid as part of research into how these creatures can change color so incredibly well, an incredibly fast. Courtesy—University of New Hampshire

Published: 4/19/2016 12:13:38 AM

It seems pretty obvious that a good way to design something is to copy a design that already works, particularly if it has worked for a million years. Hence the popularity of biomimicry, or using animals or plants or natural processes to guide the creation of manmade stuff.

This approach isn’t always successful – trying to build flying machines that copied birds’ flapping wings was not, it turns out, a great idea – but more often than not, biomimicry is a valuable way to approach innovation and design.

That’s why some UNH professors have dived, so to speak, into squid and other color-changing cephalopods in hopes of figuring out how we can make materials or fabrics that are able to switch hues in the blink of an eye.

“It’s really phenomenal the way these animals work. When you think about the time scale – they have millisecond responses – you think ‘What? This is crazy!’ ” said Leila Deravi, an assistant professor of chemistry and materials science at UNH who is a lead scientist on a recent research paper on the phenomenon.

The paper in the research journal Langmuir, which deals with systems and materials, is titled “Phenoxazone-Based Pigments to the Structure and Function of Nanostructured Granules in Squid Chromatophores,” so we’re deep in polysyllabic territory. The school says this is the first in-depth examination of how color-changing organs called chromatophores work in the skin of squid.

The UNH team chose a particular species of squid, Doryteuthis pealeii, because it is easily found in New England waters, and also because it has fewer and larger chromatophores than its more talented brethren, cuttlefish and octopuses, whose chromatic and shape-changing skills have made them YouTube stars.

The team found that one key to the squid’s ability are pigments being changed at the nano (billionth of meter) scale, understood through the behavior of electrons and the gaps between them as part of something with the delightful acronymic name HOMO-LUMO, which stands for Highest Occupied Molecular Orbit and Lowest Unoccupied Molecular Orbit. “It’s comparable to organic semiconductors that are being used in industry,” Deravi said.

All of this seems standard materials-science and molecular chemistry work, but what isn’t standard is having to cut up a dead squid to get there.

“I had to learn a lot about (squid) physiology – doing dissections properly without contamination, things like that,” Deravi said. “Until my fourth year in graduate school, I had no appreciation for natural systems, how they work, their sophistication, the protein levels that all coordinate together to give these amazing functions.”

Mixing the skill sets of biology and the harder lab sciences isn’t unusual in biomimicry studies. In fact, Deravi said it’s one thing that’s appealing in this interdisciplinary field.

“There’s not just one single research area that can truly describe some sort of natural phenomena. You need to incorporate fundamentals from a whole bunch of different fields and start to ask questions,” Deravi said.

The hope is that further understanding the molecular and atomic working of cephalopods’ skin will lead to displays that can use tiny bursts of electricity to create more colors and far more quickly than currently.

And by displays Deravi means just about anything. “Incorporate pigments into different types of materials – textiles, thin films, fabrics, paints. . . . Maybe in five years, we can have a product for people to look at,” she said. “I don’t think that is too far of a stretch.”

Five years? I don’t know about you, but the prospect of wearing a cuttlefish Halloween costume that can copy the color-changing gymnastics you see online is worth waiting for.

(David Brooks can be reached at 369-3313, dbrooks@cmonitor.com or on Twitter @GraniteGeek.)

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