Inspired by the ability among certain cephalopods like octopus and cuttlefish to change the color of their skin, engineers at the University of Illinois and the University of Houston have developed a flexible material that can detect and mimic the visual characteristics of its environment.
Many octopuses, for example, use camouflage to avoid threats and to stalk prey. They also flash their colors to communicate with other members of their species and to aid in finding a mate. The system cephalopods use to achieve this dramatic display is quite complex. Their skin is comprised of three unique layers of cells that work together to produce the effects of camouflage.
The cells at the bottom layer, called leucophores, act as a mirror to reflect colors from their immediate surroundings. The cells within the middle layer, called iridophores, also reflect color but in an iridescent fashion. And finally, chromatophores, making up the top layer, are controlled by nerves and muscles that contain small sacs full of pigment that dilate or constrict to reveal or conceal various colors.
Similar to the multi-layered skin of cephalopods, the fabric developed by the engineers is made up of distinct layers of material that work together to change color. The bottom layer consists of several rows and columns of photosensors that detect changes in light, which lie under a diode that warms when a current is applied. Above the diodes is a thin layer of silver, followed by an upper most layer of temperature sensitive dye that becomes transparent when heated. At low temperatures the material appears black, but when the photosensors detect light, a current is applied to the respective diode that heats the dye, becoming transparent to reveal the silver layer underneath.
“Our device sees color and matches it. It reads the environment using thermochromatic material,” says John A. Rogers of the University of Illinois at Urbana-Champaign and Yonggang Huang of Northwestern University.
While the technology is still in its infancy (the material only works in black and white) researchers are confident in its long term potential. New stealth technology and special ops suits with camouflage are just some of the application possibilities that are being discussed. With intense interest and funding by the US Navy, it will be exciting to see if these ideas become reality.