Imagine if you could disappear into the background at opportune occasions, blending into the wallpaper when the boss threatens or changing shape when a date is dull. Well, cephalopods can do that sort of thing, and now scientists have created a replica of morphing octopus skin for use in robots.
In a study published in the latest issue of Science (Oct. 13), researchers from Cornell University reveal how they made a morphing silicone-based membrane, inspired by cephalopod camouflage techniques. The team created a “skin” made of layers of silicone, rubber, and mesh that can assume the shape of things around it, like inanimate stones or living plants, disappearing into the background so that it’s indistinguishable.
The idea for the project came to Cornell University materials expert Itai Cohen after watching videos of cephalopods in the ocean seemingly magically conjuring themselves into existence. He was awed. Cohen told the Washington Post, “You are staring at this coral reef. You have no idea [an octopus] is there. It changes color. It changes texture. It appears out of nowhere.”
Cohen wanted to replicate this morphing effect with silicone, the primary material used in the field of soft robotics. His team had to enlist the assistance of an octopus expert, someone obsessed with the bumpiness of cephalopod skin, so they called in Roger Hanlon, a cephalopod biologist at the Marine Biology Laboratory in Woods Hole, Massachusetts. Formerly the lab’s director, and now devoted entirely to the study of marine shape shifters, Hanlon’s biography notes, “I became interested in cephalopods when I encountered an octopus on a coral reef in Panama in 1968. Its body patterning and changing coloration intrigued me, and I am still working to understand its brain and behavior.”
Hanlon could relate to Cohen’s fascination. He pointed the team at Cornell towards papillae, which are small, rounded protuberances on animal organs. “Lots of animals have papillae, but they can’t extend and retract them instantaneously as octopus and cuttlefish do,” Hanlon told Phys.org. “These are soft-bodied molluscs without a shell; their primary defense is their morphing skin.” When a cephalopod wants to look cool and attract a mate, or navigate the waters, it stays smooth, literally, according to Hanlon. Bumpiness is for defense—it helps the octopus look like and blend into rocks and other things in its environment.
To create a similar smart-morphing mechanism in imitation-octopus skin, Hanlon advised the team to layer silicone and mesh so that the skin could inflate and deflate into various shapes After a few years of work they figured it out together.
The morphing skin’s surface, is cut with lasers, creating small chambers in what seems to be a solid surface (but isn’t). Air can enter the tiny chambers, which are programmed to inflate so protuberances form on its surface in bio-inspired patterns, designed to mimic nature. Fibers embedded in the silicone produce a camouflaging texture after the silicone chambers are inflated.
In other words, the silicone skin is like a super-complex, high-tech balloon that is pre-programmed to respond to its environment in various ways. “To design a particular shape,” Cohen explained in a statement, “you figure out what its slope is at every point, then you design the amount of strain by including more or less mesh in the region.”
The team didn’t create the morphing membrane with a particular application planned but believe it has uses in soft robotics.The work was funded by a grant from the Army Research Office, which is interested in the technology for camouflage purposes. The researchers believe it may be useful in a civilian context as well: for example, it could be used in designs for flat products that can be inflated upon arrival.