Researchers at the Massachusetts Institute of Technology (MIT) have found inspiration from nature's most skilled artists in camouflage, such as octopus and squid, to develop a way to design soft materials that can change colors or fluorescence and even textures. According to Xuanhe Zhao, Assistant Professor of MIT Mechanical Engineering Department, this new material is basically an electroactive elastomer, which can easily adapt to the standard process and make use of readily available materials. This enables it to produce dynamic anti fouling coatings more economically than other assemblies of individually manufactured electronic modules. In the initial proof-of-concept demonstration, the material can be configured to change textures and fluorescence, or textures and color due to strain.
The new synthetic material is an elastomer with flexible and retractable form. "The fluorescence and texture of the material will change simultaneously depending on the applied voltage -- the actual change is that the switch flips," says Qiming Wang, a postdoctoral researcher at MIT and the first author of the theory.
Researchers observed that the cephalopod changes colors mainly by using muscles that could change the shape of tiny pigmentation sacs in the skin - for example, by shrinking circular spots that were barely visible into clear wide flat shapes. This muscle contraction can also change skin texture.
To replicate the observed phenomena, researchers used a physical phenomenon discovered in 2011 that applied voltage can dynamically change the surface texture of elastomer.
They combine this texture change with the mechanically responsive molecules embedded in the elastomer, which will cause fluorescence or color to change depending on voltage. When the voltage is released, both elastomers and molecules will return to a relaxed state.
This dynamic reconfigurable camouflage material may initially be used for military purposes, as troops and vehicles often move from one place to another. Zhao pointed out that using systems like this new elastomer, whether used in uniforms or vehicles, can bring a camouflage pattern that continuously responds to changes in the surrounding environment.
Although, researchers have to do more material experiments to induce different patterns for the same material. Up to now, they only have gotten one pattern for each material they test.
Another important potential application will be an anti fouling coating
for hulls, where microorganisms and crustacean-like organisms are most easily accumulated, thus greatly reducing the efficiency of hull propulsion.
According to early experiments, even if the surface texture changes briefly, from the smooth surface needed for rapid movement to the rough, concave and convex texture, more than 90% of the biological scaling can be quickly removed.
The study was sponsored by the U.S. Naval Research Office, the Army Research Laboratory and the Army Research Laboratory, and the National Science Foundation (NSF).