Blue-ringed octopus inspires camouflage tech

Native to the Western Pacific Ocean and Indian Ocean, the octopus uses the iridescent blue rings on its underlying brown skin to signal to other creatures, camouflage itself and ward off enemies. To mimic this action, the UCI team used wrinkled blue rings surrounding brown circles, sandwiched between a transparent proton-conducting electrode and an underlying acrylic membrane, with another identical electrode underneath. The work is published in Nature Communications.

According to senior co-author Alon Gorodetsky, the type of molecules used to fabricate the coloured blue ring layer are what endow the devices with their outstanding features, including adjustable spectroscopic properties, ease of manufacturing and stability under illumination.

“We are fascinated by the mechanisms underpinning the blue-ringed octopus’ ability to rapidly switch its skin markings between hidden and exposed states,” said Gorodetsky, UCI professor of chemical and biomolecular engineering.

“For this project, we worked to mimic the octopus’ natural abilities with devices from unique materials we synthesized in our laboratory, and the result is an octopus-inspired deception and signalling system that is straightforward to fabricate, functions for a long time when operated continuously, and can even repair itself when damaged.”

The UCI team also employed organic compounds known as acenes at the molecular level to further enhance the technology’s capabilities. Designer nonacene-like molecules - with nine linearly fused benzene rings – added to the biomimetic platform’s tunablility.

“Acenes are organic hydrocarbon molecules with a host of advantageous characteristics, including ease of synthesis, tunable electronic characteristics, and controllable optical properties,” said co-lead author Preeta Pratakshya, from UCI’s Department of Chemistry.

“Our nonacene-like molecules are exceptional among acenes because they can survive years of storage in air and over a day of continuous irradiation with bright light in air. No other expanded acene displays this combined long-term stability under such harsh conditions.”

In laboratory tests, the team found that the bioinspired devices could change their visible appearance over 500 times with little or no degradation, while also autonomously self-repairing. According to the researchers, the technology exhibited a desirable combination of capabilities in the ultraviolet, visible light, and near-infrared parts of the electromagnetic spectrum.

“The photophysical robustness and general processability of our nonacene-like molecule – and presumably its variants – opens opportunities for future investigation of these compounds within the context of traditional optoelectronic systems such as light-emitting diodes and solar cells,” said Gorodetsky.