Squid skin inspires infrared stealth camouflage

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Researchers at UC Irvine’s Henry Samueli School of Engineering have created a biomimetic infrared camouflage coating inspired by pencil squids.

Led by Alon Gorodetsky, an assistant professor of chemical engineering and materials science, the team produced reflectin – a structural protein essential in the squid’s ability to change colour and reflect light – in common bacteria and used it to make thin, optically active films that mimic the skin of a squid.

With the appropriate chemical stimuli, the film’s colouration and reflectance can shift back and forth, which allows the films to disappear and reappear when visualised with an infrared camera.

Infrared detection equipment is employed extensively by military forces for night vision, navigation, surveillance and targeting. According to UC Irvine, the novelty of this coating lies in its functionality within the near-infrared region of the electromagnetic spectrum, roughly 700 to 1,200 nanometres, which matches the standard imaging range of most infrared visualisation equipment. This region is not usually accessible to biologically derived reflective materials.

‘Our approach is simple and compatible with a wide array of surfaces, potentially allowing many simple objects to acquire camouflage capabilities,’ said Gorodetsky, whose work has possible applications in infrared stealth camouflage, energy-efficient reflective coatings and biologically inspired optics.

This is just the first step in developing a material that will self-reconfigure in response to an external signal, he added in a statement. The Samueli School researchers are currently formulating alternative, non-chemical strategies for triggering colouration changes in the reflectin coating.

‘Our long-term goal is to create fabrics that can dynamically alter their texture and colour to adapt to their environments,’ Gorodetsky said. ‘Basically, we’re seeking to make shape-shifting clothing – the stuff of science fiction – a reality.’

The work is detailed in Advanced Materials. Others on the UC Irvine team include Long Phan, David Ordinario, Emil Karshalev, Jonah-Micah Jocson and Anthony Burke. Ward Walkup of the California Institute of Technology also contributed to the study.