Soft Robots That Can Change Color

Most of the time, scientists derive inspiration from nature. Scientists at Harvard University have done just that. They have developed a soft silicone-based robot modeled on
creatures like starfish and squid, that have the capacity to camouflage themselves according to their surroundings.

The experiment was carried out by a team of researchers led by George M. Whitesides, a professor of the Woodford L. and Ann A. Flowers University. It has been described in the Aug. 16 edition of the journal Science.

According to researcher Stephen Morin, a postdoctoral fellow in Chemistry and Chemical Biology and first author of the paper, "such a dynamic coloration system will be widely accepted over the period of time. It has the potential of helping doctors plan complex surgeries to acting as a visual marker to help search crew in disaster related missions."

"When we began working on soft robots, we were inspired by soft organisms, including octopi and squid," Morin said. "One of the fascinating characteristics of these animals is their ability to control their appearance, and that inspired us to take this idea further and explore dynamic coloration. I think the important thing we've shown in this paper is that even when using simple systems -- in this case we have simple, open-ended micro-channels -- you can achieve a great deal in terms of your ability to camouflage an object, or to display where an object is."

"One of the most interesting questions in science is 'Why do animals have the shape, and color, and capabilities that they do?'" said Whitesides. "Evolution might lead to a particular form, but why? One function of our work on robotics is to give us, and others interested in this kind of question, systems that we can use to test ideas. Here the question might be: 'How does a small crawling organism most efficiently disguise (or advertise) itself in leaves?' These robots are test-beds for ideas about form and color and movement."

In order for the robot to mimic the colors and pattern of the environment, the researchers used color layers in camouflage molds, using 3D printers. Micro-channels are crafted into these molds with the help of silicone and are topped with another layer of silicone. The layers can be created as a separate sheet that sits atop the soft robots, or incorporated directly into their structure. After the completion, researchers can pump color liquid into the channels. The system's camouflage capabilities aren't limited to visible colors, though.

The process of pumping heated or cooled liquids into the channels helps to camouflage the robots thermally. In another test, researchers tried their hand at using fluorescent liquid that gave the color layers a glow in the dark.

Morin envisions that robots could use this system to signal their presence both to other robots and people.

He concluded saying, "What we hope is that this work can inspire other researchers to think about these problems and approach them from different angles. There are many biologists who are studying animal behavior as it relates to camouflage, and they use different models to do that. We think something like this might enable them to explore new questions, and that will be valuable."