Sep 5th 2017

Cloaking Device Device Development Inspired by Natural Stealth

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Octopuses do it. Cuttlefish and flounders do it. And James Bond spied on villains in an Aston Martin that had its own cloaking device in the film “Die Another Day.”

“It” is adaptive camouflage, a type of stealth technology that could lead to cloaking devices for military and many other uses.

Keep in mind that true invisibility is the stuff of science fiction for now. Even if an object is indistinguishable from its surroundings, it’s still there. It still has mass and may still emit a heat signature or sound (which is why Harry Potter had to be quiet while creeping around Hogwarts under his invisibility cloak).

Scientists have discovered several methods in nature that could also be adapted to bring color-changing technology into the industrial world. Northrop Grumman has supported research into stealth technology over the years, including the Rochester Cloak, a system of lenses that creates the illusion of invisibility.

Nature’s Stealth Machines

As researchers have uncovered the secrets behind the amazing mimicry skills of some sea creatures, the possibility of a cloaking device is coming closer to reality. We have a lot to learn from these creatures which can completely change their coloring to match their surroundings in seconds, blending into the sea floor or fading into the sunlight near the surface.

A peacock flounder changing colors depending on the colors of its surroundings (Wikimedia Commons)

The bottom-dwelling peacock flounder can disappear into a stony seafloor to wait for prey. The flounder’s color-matching ability is so advanced it can match a checkerboard pattern placed beneath it. Mechanisms behind the flounder’s abilities are not fully understood but it’s believed to involve the release of hormones that bring different pigments to the surface of the skin based on what the fish sees. For a camouflage system, cameras would replace the flounder’s stalked eyes and send signals to adaptive camouflage coatings material, perhaps made of meta materials.

For the cephalopods — octopus, squid, cuttlefish — their skin contains pigment-rich cells known as chromatophores that react to external stresses such as a predator to change color to hide or communicate with others.

Scientists have begun replicating this process, called visual appearance modulation, with a new multilayered camouflage material. The top layer is filled with temperature-sensitive dye, which sits atop a layer of white reflective tiles composed of circuitry that controls the temperature of the dye layer. The foundation is a photoreceptor layer that analyzes the light streaming through notches in the upper layers so the system knows when and how to change color. Color changes can happen in two to three seconds. However, the system is still only a pale imitation of the sophistication that an octopus lying in wait for prey can muster on the ocean floor.

In addition to military camouflage applications, the technology could be used for clothing that changes color, or architectural features such as wall coverings that adapt to lighting changes.

Cloaking Devices on the Road

Adaptive camouflage systems built on these findings have been tested by U.S. and British armed forces, allowing soldiers to disappear from sight, and also be shielded from thermal imaging detection.

In the aforementioned Bond film, the MI6 boffins equipped an Aston Martin V12 Vanquish with a coating that projected the car’s surroundings onto the car’s surface so that it blended into its environment. While that was the stuff of movie magic, Mercedes-Benz developed a similar system and gave it some real-world testing. The new zero emissions F-Cell car was equipped with a camera on the right side, and a sheet of video display material on the left. The camera shot video on the passenger side of the car and displayed it in real time on the driver side of the automobile. Pedestrians and drivers had the sensation of seeing right through the car.

While hiding in plain sight is an obvious goal for military applications, there are commercial applications as well in safety enhancements, education, arts and entertainment. It will take time for researchers to turn nature’s secrets into products for the marketplace, but adaptive camouflage could be ready for the spotlight in a surprisingly short time.

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