Squid-skin displays bring us closer to biotech camouflage

Cephalopods are curious creatures, able to flex their bodies into nifty shapes and camouflage themselves from sight. Unsurprisingly, they have also been inspiring biomimicry-led designs for years because of this. This month a paper to be published in Nature Communications deals with their flexi-strechy skills and describes how man can now engineer an elastic film that lights up when stimulated using electricity. Meanwhile, a team of US material scientists has opted to create a new method of colour display using a technique they say will get us that much closer to the holy grail of cephalopod biomimicry studies: camouflaging “squid skin” that morphs into background shades automatically, (otherwise known as a metamaterial).

Octopus pretending to be a stone

Octopus pretending it’s a a stone (Source: Shutterstock)

The group, led by Rice University’s Laboratory for Nanophotonics (LANP), has used aluminium nanoparticles to engineer a display technology that uses the same reds, blues and greens you might see in LCD screens. Five-micron-square pixels — 40 times smaller than the pixels in standard LCDs — deliver rich colours, with each containing a few hundred aluminium nanorods (the nanorods acting as a replacement for colour dyes usually used, which have a shorter life span and will eventually fade or change due to damage).

Using aluminium to deliver coloured displays has long-been considered — it’s cheap, there’s plenty of it and its compatible with production methods already in place, argue the Rice team. However, no one had nailed the colour richness. The LANP team has remedied this by altering the nanorods array — the space between each nanorod — and changing the lengths of the individual nanorods

“This arrangement allowed us to narrow the output spectrum to one individual colour instead of the typical muted shades that are usually produced by aluminium nanoparticles,” said Jana Olson, an LANP researcher and co-author on a paper on the technology published in PNAS.

Olson could work out the right distances and nanorod sizes by adhering to theoretical calculations shared with the team by a fellow Rice researcher working in the physics and astronomy department. The nanorods themselves measured 100 nanometres long by 40 nanometres wide, but the spacing and interactions the team engineered were tweaked to let the pixels produce different colours.

The authors write in PNAS that not only are their methods compatible with usual manufacturing methods for display, they are also scalable.

Still, it doesn’t yet quite sound as exciting as the squid-skin inspired materials being promised. For instance, like the ones a University of California Irvine team is working on to produce infrared camouflage for stealthy soldiers, using a protein called reflectin (yes, that’s its real name, and its common in cephalopods).

However, there is hope for squid-skin displays yet. The Rice team wants to combine this new approach with a series of other work going on related to light-sensing and pattern display. As LANP director Naomi Halas promises in a release: “We hope to eventually bring all of these technologies together to create a new material that can sense light in full colour and react with full-colour camouflage displays.”

“We know cephalopods have some of the same proteins in their skin that we have in our retinas, so part of our challenge, as engineers, is to build a material that can ‘see’ light the way their skin sees it, and another challenge is designing systems that can react and display vivid camouflage patterns. Our goal is to learn from these amazing animals so that we could create new materials with the same kind of distributed light-sensing and processing abilities that they appear to have in their skins.”

If you want to find out more about the flexi-stretchy skin being deliberated over in Nature Communications this month, our US colleagues have detailed the study over at Wired.com.

Original article: Wired

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