Scientists have successfully wowed us with some pretty amazing bio-inspired materials in recent years, from 3D printed shark skin to gecko-inspired climbing paddles. Now, researchers have developed an incredible new cephalopod-inspired camouflage material that is capable of automatically sensing and adapting to the color of its surroundings. The study has been published in PNAS.
Octopuses, squid, cuttlefish and various other members of the class Cephalopoda display the remarkable ability to quickly change color depending on their surroundings. This is used for a variety of purposes such as camouflage, communication, predation and reproduction. In recent years, scientists have started to understand how these animals achieve this amazing phenomenon, which has spurred efforts to mimic these systems.
The patterns and colors displayed by cephalopods are due to different layers of cells stacked together in the skin. Cells of the top layer are equipped with tiny, pigment-containing organelles called chromatophores that are controlled with a ring of muscles. When the sac expands, color can be seen; if it shrinks, the pigment becomes hidden. The next layer contains iridophores that reflect various colors of the environment such as blues and greens. The bottom layer contains cells called leucophores that scatter ambient light, which further contributes to the ability of these animals to blend into the environment. Like our eyes, their skin is also equipped with light-sensitive molecules called opsins.
Inspired by this natural system, researchers from the University of Houston and the University of Illinois developed a flexible material capable of sensing and responding to its surroundings. Much like cephalopod skin, the material is composed of several ultrathin layers that serve different purposes.
The bottom layer contains an array of photosensors on flexible substrates that are capable of detecting changes in light. These patterns of light are then transmitted to actuators which play a similar role to muscles within the cephalopod skin. Next, there is a sliver of silver which creates a white background, much like the leucophores. Finally, the uppermost layer contains a temperature-sensitive pigment that switches from black to transparent at 47oC. This temperature change is produced by the underlying actuators.
The researchers put this new material to the test and found that it could adapt to changing patterns of light within 1 to 2 seconds, producing matching black-and-white patterns without user input. Check out a demonstration here:
While the system is pretty inefficient at the moment and restricted to black-and-white, the researchers believe it could be improved by adapting the existing technology, for example through the incorporation of solar cells. They could also exchange the dye for a substance that is able to offer a wider range of colors.
While the research may have been funded by the Office of Naval Research, the scientists believe that the potential uses of artificial systems such as this extend far beyond the military, for example color-changing fabrics for fashion and interior design. However, lead researcher Prof John Rogers stressed to the BBC that while these ideas may seem cool, the team are focusing their efforts on the engineering side, rather than color-changing wallpaper.