Cephalopod IR...

Warning signs: the greater blue-ringed octopus changes its appearance when threatened using techniques that have inspired an adaptive infrared reflector. (CC BY-SA 2.5/Jens Petersen)

Topics: Bioengineering, Biology, Optical Physics, Materials Science, Nanotechnology

A simple device with tuneable infrared reflectivity has been made by mimicking the adaptive properties of the skin of octopuses and related animals. Chengyi Xuat, Alon Gorodetsky and George Stiubianu of the University of California, Irvine created the device using a dielectric elastomer and say that it overcomes many of the limitations of previous adaptive infrared-reflecting systems.

Reflecting infrared radiation is important for many technologies, ranging from building insulation to spacecraft components. But most of the materials used to reflect radiation in the infrared region are static: they are unable to respond and adapt to changes in the environment. Some adaptable infrared-reflecting systems have been developed, but they tend to be complex and difficult to control, while also lacking spectral tunability and requiring high operating temperatures.

Inspired by the skin of cephalopods – squid, octopuses, and cuttlefish – Gorodetsky and colleagues have now developed an adaptable infrared-reflecting system that they say is easy to control, can respond rapidly and be used repeatedly. The system also has a tuneable spectral range and works at low temperatures.

Many cephalopods can rapidly change the colour and patterning of their skin. This is done for both camouflage and signalling, and is enabled by pigment cells with adjustable spectral properties that can response within hundreds of milliseconds. These yellow, red, and brown cells, known as adaptive chromatophores, are packed with pigment granules and can be expanded and contracted by radial muscles. As their size and shape changes so do the wavelengths of light that they absorb and reflect.

Octopus skin inspires new infrared reflector, Michael Allen, Physics World