Camouflage is one of nature’s best “gotchas!”. From squid who turn themselves the color of ocean sand to brightly colored chameleons, natural camouflage is a powerful evolutionary skill to avoid predators.
But unlike our animal counterparts, human beings aren’t typically so gifted in this art of disguise. While a stealthy wildlife photographer can don a green and brown speckled jacket, it’ll never be as dynamic or flexible as that of a squid or octopus. That is, until now.
In a new study published Monday in the journal Proceedings of the National Academy of Sciences, a team of researchers has designed a new kind of camouflage technology that can transform someone’s appearance using only light. Borrowing from the biology of cephalopods, this light-driven technology works by creating and relaxing wrinkles in a colored film to scatter color information.
The authors write that this low-cost technology could be especially useful for the development of dynamic and responsive military technology that goes beyond camo-colored clothing.
“Camouflage has broad applications in nature, engineering, and the military,” the authors write in their paper. “This work demonstrated a feasible strategy for adaptive visible camouflage based on light-driven dynamic surface wrinkles.”
What’s new — Designing camouflage technology is hardly a new idea, but the authors write that what sets their work apart is its low-tech approach.
“To date, many adaptive camouflage materials and systems have been reported,” the authors write.
“However, most dynamic camouflage systems work in active form and require extra mechanical or electric stimuli and even external sensors,” they continue. “These requirements increase the design complexity and mass, leading to clumsiness and an awkward appearance. Moreover, high supply voltages increase the energy consumption.”
Instead of relying on extra power supplies or sensors, this team’s technology can work using just sunlight.
Why it matters — At the moment, this technology’s major application is in the development of next-gen camouflage technology for the military, the authors say, which could help reduce loss of life during combat.
“Camouflage enables a device or a robot to seamlessly blend into its environment for effective environment and species monitoring,” the authors write. “[Additionally,] reconnaissance and anti-reconnaissance play an important role in target survivability on the battlefield. Camouflage helps the military objects to avoid detection by the enemy, thus resulting in fewer casualties.”
In addition to its military applications, the authors write that this technology could also have consumer tech applications including smart displays, information storage, and anticounterfeiting technology.
What they did — To create the animal-like “skin” of their camouflage tech, the researchers created a sandwich of two different film types: a rigid polymer film and a soft substrate layer mixed with pigments.
This soft, pigmented layer expands and contracts when struck with light waves, and the “mismatch” between the states of these two layers creates reversible wrinkles in the skin. From there, it was a simple trick of optics — the science of scattering light — that determined whether or not the skin appeared colorful or hidden.
When all scrunched up, the team found that the light was strongly scattered off the surface. This is likely because there was more surface area to scatter off of — think of light scattering of a cut diamond versus flat glass. In this wrinkled state, the skin showed vibrant colors.
However, when the wrinkles went flat, the skin took on the color of its surroundings instead — effectively camouflaging it.
What’s next — Right now, this technology has only been demonstrated on a small scale but the team has plans to continue to scale and develop it in the future.
One potential avenue for growth would be in the skin's color sensing and dynamic adaptability. Right now, the background color that the flat skin defaults to is preprogrammed to match its surroundings. In the future, this technology may be able to intelligently color match its surroundings instead.
Abstract: Camouflage is widespread in nature, engineering, and the military. Dynamic surface wrinkles enable a material the on-demand control of the reflected optical signal and may provide an alternative to achieve adaptive camouflage. Here, we demonstrate a feasible strategy for adaptive visible camouflage based on light-driven dynamic surface wrinkles using a bilayer system comprising an anthracene-containing copolymer (PAN) and pigment containing poly(dimethylsiloxane) (pigment-PDMS). In this system, the photothermal effect–induced thermal expansion of pigment-PDMS could eliminate the wrinkles. The multiwavelength light-driven dynamic surface wrinkles could tune the scattering of light and the visibility of the PAN film interference color. Consequently, the color captured by the observer could switch between the exposure state that is distinguished from the background and the camouflage state that is similar to the surroundings. The bilayer wrinkling system toward adaptive visible camouflage is simple to configure, easy to operate, versatile, and exhibits in situ dynamic characteristics without any external sensors and extra stimuli.