Color-Changing Material That Mimics Octopus Skin Could Be Used for Robotics
Octopuses have the incredible ability to quickly change and adapt their skin to camouflage themselves in their surroundings – an ability that researchers have worked to adapt to synthetic materials. In a recent study published in Natureresearchers have revealed a new material capable of rapidly swelling into different colors, textures and patterns with a resolution finer than a human hair.
“Textures are crucial in how we perceive objects, both in how they look and how they feel,” Siddharth Doshi, a doctoral student in materials science and engineering at Stanford and first author of the paper, said in a press release. “These animals can physically change bodies at a near-micron scale, and we can now dynamically control the topography of a material – and the visual properties associated with it – at that same scale.”
This new research could lead to better camouflage for humans and some robotic systems, as well as more dynamic displays for wearable technology. The research team believes it is also possible that this new material could open new doors in nanophotonics – the control and manipulation of light at the nanometer level, which could help improve encryption, electronics and biology.
Learn more: Shark skin and cicada wings inspire new antimicrobial cutting boards
Octopus inspires a new synthetic material
For the study, the team used electron beam lithography – a patterning technique commonly used in semiconductor manufacturing – and combined it with a polymer film that swells upon absorption of water.
When the researchers shined electron beams at the polymer, they were able to manipulate the swelling in specific regions of the material. As a result, they created detailed patterns that were only revealed when the polymer film was wet.
The team was initially surprised by these results. In previous research, Doshi scanned nanostructures on a polymer film using an electron microscope, a technique that uses electron beams to generate a high-resolution image. However, instead of throwing away these film samples, Doshi recycled them and discovered that when scanned again under an electron microscope, the previously imaged areas behaved differently and even changed color.
“We realized we could use these electron beams to control topography at very fine scales,” Doshi said. “It was really a coincidence.”
This electron beam pattern is so precise that researchers created a nanoscale model of El Capitan in Yosemite National Park. Depending on the amount of water added to the film, they could also determine how to induce light scattering, thereby manipulating the film to appear matte or shiny. To return the film to normal, the team applied an alcohol-based solvent to remove the water. Once dry, the film was completely flat.
“There is simply no other system that can be this soft and bouncy, and that can be modeled at the nanoscale,” Nicholas Melosh, professor of materials science and engineering and lead author of the paper, said in the press release. “You can imagine all kinds of different applications.”
Adaptable material for the future
Although there is still much to learn about this material, researchers can manually change the color and texture of the film. They may not be as fast or as precise as an octopus, but they come close.
“We want to be able to control this with neural networks – essentially an AI-based system – that could compare the skin and its background and then automatically modulate them to match in real time, without human intervention,” Doshi said.
In addition to its use for camouflage, the team believes it could be applied to some research in bioengineering and robotics.
“Small changes in the properties of soft materials over micron distances are finally possible, which will open up all kinds of possibilities,” Melosh said. “I think there are a lot of exciting things to come.”
Learn more: Octopuses change color in milliseconds, even if they are colorblind
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