Cephalopods, which include octopuses, squid, and cuttlefish, are among nature’s most skillful camouflage artists, able to change both the color and texture of their skin within seconds to blend into their surroundings—a capability that engineers have long struggled to duplicate in synthetic materials. Now a team of researchers has come closer than ever to achieving that goal, creating a flexible material that can change its color or fluorescence and its texture at the same time, on demand, by remote control.
The results of their research have were published in a paper by a team led by Massachusetts Institute of Technology, Cambridge, Assistant Professor of Mechanical Engineering Xuanhe Zhao and Duke University, Durham, N.C., Professor of Chemistry Stephen Craig.
Zhao says the new material is essentially a layer of electro-active elastomer that could be quite easily adapted to standard manufacturing processes and uses readily available materials. This could make it a more economical dynamic camouflage material than others that are assembled from individually manufactured electronic modules.
While its most immediate applications are likely to be military, Zhao says the same basic approach could eventually lead to production of large, flexible display screens and anti-fouling coatings for ships. In its initial proof-of-concept demonstrations, the material can be configured to respond with changes in both texture and fluorescence, or texture and color. In addition, while the present version can produce a limited range of colors, there is no reason that the range of the palette cannot be increased, Craig says.
Learning from nature
Cephalopods achieve their remarkable color changes using muscles that can alter the shapes of tiny pigment sacs within the skin — for example, contracting to change a barely visible round blob of color into a wide, flattened shape that is clearly seen. “In a relaxed state, it is very small,” Zhao says, but when the muscles contract, “they stretch that ball into a pancake, and use that to change color. The muscle contraction also varies skin textures, for example, from smooth to bumpy.” Octopuses use this mechanism both for camouflage and for signaling, he says, adding, “We got inspired by this idea, from this wonderful creature.”
The new synthetic material is a form of elastomer, a flexible, stretchable polymer. “It changes its fluorescence and texture together, in response to a change in voltage applied to it — essentially, changing at the flip of a switch,” says Qiming Wang, a co-author.
