Whether it’s Harry Potter’s invisibility cloak or James Bond’s vanishing Aston Martin in Die Another Day, invisibility has been a long-sought-after human dream. Why suffer through a painful dinner party when you could quite literally blend into the upholstery?
This vanishing trick is something that the animal kingdom, including chameleons and cuttlefish, have already mastered. However, developing the technology to pull off the same feat for humans has been much more challenging. That could soon be changing, though, thanks to a new camouflaging technology developed by material scientists in South Korea.
This technology could transform everything from stealthy military tech to disappearing buildings. What you see isn’t always as it seems.
Published Tuesday in the journal Nature Communications, the researchers demonstrate how this technology can transform a soft robot into an artificial chameleon capable of changing its appearance in real-time to match its environment.
Seung Hwan Ko is a senior author on the paper and professor of mechanical engineering at Seoul National University. He tells Inverse that in the future, this technology could transform military technology as we know it.
“The first application will be military, [Such as] covert intel robots [or] ‘actively’ camouflaging military uniforms,” says Ko.
Camouflage on military uniforms today is “passive,” Ko explains, meaning the patterns cannot respond dynamically to their environment. Weaving the team’s new technology into these coats would mean that soldiers could actively blend into any new environment.
What’s new — In nature, camouflaging animals can hide in plain sight by contracting and contorting their skin to change the pigment displayed therein. As a natural “technology,” their color-changing skin is both efficient and compact. Achieving the same fidelity for biomimicking tech, however, is not so simple.
Like its animal counterpart, this soft robot chameleon can change color with its environment.
The more sensors, pixels, and flexibility you add to such biomimicking skins, the higher the complexity of the entire system. This makes the task “exceptionally challenging,” the authors write.
To get around this problem, Ko and colleagues introduced a new approach that relies on layers of compact color-changing ink displays, stacked nanowire heaters, and small color sensors to get the job done.
Stacked together like the pages of a book, Ko says this technology allows the “skin” to capture both the color and pattern of its surroundings and react in real-time.
Why it matters — Beyond military applications, Ko says this technology could also trickle down to everyday consumers, whether that be purchasing an invisible hoodie or designing a camouflaging house.
You’ll never feel over or underdressed again with clothes that can “changes its color and patterns according to your taste or environment,” Ko says.
How it works — In honor of this technology’s animal inspiration, the team designed a tethered chameleon robot to demonstrate how uses for their new skins. The first step, says Ko, is for the skin to acquire information about the color of its environment through color sensors.
Ko says they chose to use just color sensors instead of full vision sensors, eliminating extra bulk for the robot.
Once sure of its surroundings, the color sensors then transfer this information to the skin, where heat is adjusted throughout to change which colors are displayed — kind of like how mood rings are supposed to change color based on your body heat. While this technique works best on monochromatic surfaces, Ko says it’s also capable of matching patterns as well thanks to built-in multi-layered skin patterns.
That said, the skin is still far from perfect. One big obstacle the team worked to overcome was keeping external temperature — like snow on a cold day — from changing the skin's temperature, and thus the color. The team found that applying feedback controllers could help regulate these temperature spikes or dips.
What’s next — Ko says the team isn’t satisfied with these successes and has big plans to take their technology beyond a teetering, robot chameleon. Including integrating A.I.
“We are planning to explore an untethered and fully autonomous chameleon robot,” says Ko.
“We [also] plan to conduct follow-up research on an artificial intelligence-based sensing system that detects not only color but also patterns of various surrounding backgrounds. Through this, we could develop a more advanced artificial camouflage system.”
Abstract: Development of an artificial camouflage at a complete device level remains a vastly challenging task, especially under the aim of achieving more advanced and natural camouflage characteristics via high-resolution camouflage patterns. Our strategy is to integrate a thermochromic liquid crystal layer with the vertically stacked, patterned silver nanowire heaters in a multilayer structure to overcome the limitations of the conventional lateral pixelated scheme through the superposition of the heater-induced temperature profiles. At the same time, the weaknesses of thermochromic camouflage schemes are resolved in this study by utilizing the temperature-dependent resistance of the silver nanowire network as the process variable of the active control system. Combined with the active control system and sensing units, the complete device chameleon model successfully retrieves the local background color and matches its surface color instantaneously with natural transition characteristics to be a competent option for a next-generation artificial camouflage.