Scientists Built an Artificial Skin That Changes Color and Texture Like an Octopus

Look closely. Credit: Wikimedia Commons Octopuses are the undisputed kings of camouflage. Whereas engineers have learned to mimic the colors, octopuses also match the texture, disappearing into the background with a level of sophistication that has baffled scientists for decades. Now a team at Stanford University has come strikingly close to cracking the code. In a study published in Nature , researchers describe a soft, flexible material that can rapidly change both its color and its surface texture, revealing intricate patterns finer than a human hair. The research links optics and soft materials to produce surfaces that change in ways familiar from living organisms. “Textures are crucial to the way we experience objects, both in how they look and how they feel,” said Siddharth Doshi, a doctoral student in materials science and engineering at Stanford and the study’s first author. “These animals can physically change their bodies at close to the micron scale, and now we can dynamically control the topography of a material-and the visual properties linked to it-at this same scale.” Writing Textures with Electrons Time-lapse of the evolution of color patterns in a soft photonic skin sample. Credit: Siddharth Doshi The foundation of this new “photonic skin” is a thin film of a common conducting polymer called PEDOT:PSS. You’ve likely already interacted with it-it’s used in displays, solar cells, and bioelectronics. But the polymer has a useful quirk: its structure rearranges and swells when exposed to water or certain solvents. The Stanford team discovered they could precisely control that reversible deformation using electron beams, the same tools used to etch nanoscale features onto computer chips. By exposing different regions of the polymer film to different doses of electrons, they subtly altered how much water each region could absorb later. When the film is dry, it lies flat and featureless. Add water, and carefully programmed landscapes rise up. The patterns appear fast, within seconds, and can be erased just as quickly. The researchers showed that they could switch the same film through hundreds of swelling and shrinking cycles with little degradation. × Thank you! One more thing... Please check your inbox and confirm your subscription. Using electron-beam patterning, the team recreated a nanoscale topographic replica of Yosemite’s El Capitan. When wet, the iconic granite monolith emerges from an otherwise smooth surface; when dry, it vanishes again. Texture alone, however, is only half of what makes octopus skin so effective. Turning Texture Into Color Of course, texture is only half the battle. In living cephalopods, color comes from chromatophores, pigment-filled cells that expand and contract. Meanwhile texture comes from muscle-driven protrusions called papillae. The two systems are controlled independently, giving octopuses their remarkable visual range. To mirror that separation, the Stanford researchers paired their shape-shifting polymer with thin layers of gold. When a single gold layer coats the polymer, swelling creates microscopic hills and valleys that scatter light in many directions. The surface shifts from glossy to matte, changing how it reflects its surroundings. This control over how shiny...

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