Octopuses and their cephalopod cousins are the undisputed masters of disguise. An octopus can change its color, texture and luminosity faster than you can say "camouflage."
So far our lowly human attempts at imitation have been quite crude. But a flashy new smart material might just be our closest step yet.
The main tool the octopus uses for its visual display is a cell called a chromatophore. These small, pigment-filled sacs expand and contract to create an array of colors and patterns. How does the octopus decide what colors and patterns to make? Recent research suggests that octopuses can also sense light—and possibly even color—through photo-sensitive cells (called opsins) in their skin.
The idea of a material that can both sense and create visual change is quite appealing to science (and the military). Renowned cephalopod researcher Roger Hanlon, a senior scientist at Woods Hole Marine Biological Laboratory, and John Rogers, a professor of materials science and engineering at the University of Illinois at Urbana-Champaign (whose previous work includes flexible temporary tattoo-like circuits), teamed up with a crew of international researchers to create a changing heat- and light-sensitive sheet of pixels, described earlier this week in Proceedings of the National Academy of Sciences.
The color change here is only black and white. But it mimics the octopus's skin by using what the researchers call "artificial chromatophores" that employ a heat-sensitive dye. When the temperature surpasses 47 degrees Celsius, the "cell" turns clear. A photo-sensitive layer sits below these faux-chromatophores. Small holes in the surface allow light to penetrate to the light-sensing portions.
So far, different appearances "including triangles, arrays of dots and even random patterns can be achieved," the researchers note. Not exactly an ocean of camo options, but certainly more sophisticated than the standard, static branch-and-mud pattern of current military-issue gear.
A future iteration of this technology might be able to be "wrapped onto solid objects to modulate their visual appearance," the researchers write. And that could serve "consumer, industrial and military applications."
When I spoke with researchers a few years ago working on this same problem with nanotechnology at Rice University, they were excited about potential uses for these sorts of reading-writing materials. They suggested clothing that could deflect heat if it sensed it was hot outside, internal sensors that could alert a patient or doctor of a health change, or even wallpaper that could sense—and report—how many people were in a room.
The current configuration can change appearance in a second or two. A snail's pace compared with the octopus. And it still lacks color. But just about all technology has to crawl before it can run. Or swim.
Read more about octopuses' ridiculous camouflaging abilities in Octopus! The Most Mysterious Creature In the Sea.
Illustration courtesy of Ivan Phillipsen