She Blinded Me with Science! 8/23/14

She Geek Eris drops a knowledge egg on dat ass via her segment on local radio show The Week in Geek. Here are this week's topics:

Could You Camouflage like a Cephalopod One Day?

Forget maxing out your level in Obfuscate; when it comes to blending in, vampires ain't got nothin' on octopi! 

Mad hide and seek skillz.

Cephalopods (mollusks with arms attached to their heads like octopus, squid, and cuttlefish) are masters of camouflage because it is their main form of protection. Their bodies are covered in a layer of thousands of chromatophores, color-changing cells just below the skin. Each cell contains pigment and can be expanded or contracted to accentuate or subdue the visibility of their pigment depending on the desired effect. For instance, if the octopus needs to blend into a piece of red coral, the chromatophores containing red pigment would be expanded while the others contracted, essentially turning the octopus red. Some cephalopods also have a layer of reflective plates in their skin in addition to chromatophores which allow them to either appear iridescent or simply reflect the colors around them in order to blend in even more completely. Most importantly to this research, cephalopod skin also contains a layer of photosensitive cells. These cells are able to sense light and patterns without the use of the cephalopod's eyes or even its brain, which allow it to utilize its camouflage technique almost instantaneously.

Super close up of a squid's skin showing the chromatophores.

Inspired by this amazing ability, researchers at the University of Houston and University of Illinois at Urbana-Champaign have developed a super thin, flexible film that could one day become a Cloak of Invisibility. (Take that Harry Potter! Not so special now, are you?!) The film uses several layers made to function autonomously, like cephalopod skin, to adapt to changes in light. The first layer consists of a grid-like pattern of dye sacs that change color depending on temperature. The dye is an opaque black at room temperature, but turns translucent when heated to 47 degrees Celsius (116F). After that is a layer of bright silver which acts as a background. Then, to mimic the muscles used to contract and expand a cephalopod's chromatophores, is a layer of diodes used to heat the dye and cause it to change color. Finally, the last layer contains a light detector that constantly monitors the film and causes the diodes to heat up when it is hit by light.

Spelling out the University of Illinois initials with the light sensitive film.

Clearly, this technology is in its infancy, and we won't be sneaking into the Restricted Section of the Hogwarts library any time soon, but this prototype is pretty bad ass all the same. The fact that the film is flexible, and incredibly thin (about the width of two hairs) already, means it will likely be much easier to adapt it for practical use. Additionally, the reaction time may not be milliseconds like a cephalopod, but it is still super quick at only a few seconds, and the researchers believe they will be fairly easy to improve the mechanism to no longer require a temperature change to operate, and are even planning on adapting the design to include more colors.

(Ed Yong wrote a fantastic article for National Geographic and included some short videos of the film in action, you can find it here.)