There are robots inspired by earthworms, babies and fish. Now the cephalopods, in addition to inspiring octopus-like robot tentacles, gave a team of Harvard scientists the idea of a robot that was soft, squishy and changes colors.

Stephen Morin, a postdoctoral fellow in chemistry, designed the color-changing system. He used layers of silicone "skin," produced on a 3-D printer. The skin has channels in it that allow dyes to be pumped through. The robot itself is a four-legged device that moves when air is pumped into the limbs. Morin told Discovery News that he and his colleagues chose that method because compressed air is easy to work with. Making the robot out of silicone makes it cheaper.

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"This characteristic presents the opportunity to make many robots, at low cost, so that you don’t feel bad about losing one," Morin said in an email.

Given the kinds of applications Morin envisions, cost is important. Search-and-rescue operations in a collapsed building, for instance, require a robot that can squeeze into tight spaces that rigid robots can't. The ability to change color means it can either squiggle by unnoticed or glow in the dark to light the way. Another use might be simulating surgery. "Devices could be made to look, feel, and 'act' like organs," Morin said. "If a training surgeon cut into the wrong place the device would 'bleed.'"

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A dye that glows can be pumped through the channels, changing the device's color. Or the temperature of the dye can be cooled so that the robot can't be seen in infrared light — like the kind used with night-vision goggles to see the heat that living bodies give off.

Details of the work were published the journal Science. The research was performed by the Whitesides Research Group and supported by the Department of Energy and the Defense Advanced Research Projects Agency.

Credit: S. Morin, Harvard University