SOFT ROBOT CHANGES COLOR

Researchers have developed a system — inspired by nature — that allows the soft robots to either camouflage themselves against a background, or to make bold color displays. Such a “dynamic coloration” system could one day have a host of uses, ranging from helping doctors plan complex surgeries to acting as a visual marker to help search crews following a disaster.

Just as with the soft robots, the “color layers” used in the camouflage start as molds created using 3-D printers. Silicone is then poured into the molds to create micro-channels, which 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. Once created, researchers can pump colored liquids into the channels, causing the robot to mimic the colors and patterns of its environment.The system’s camouflage capabilities aren’t limited to visible colors though.

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.”

 HOW THEY CHANGE COLOR?

Just as with the soft robots, the “color layers” used in the camouflage start as molds created using 3-D printers. Silicone is then poured into the molds to create micro-channels, which 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. Once created, researchers can pump colored liquids into the channels, causing the robot to mimic the colors and patterns of its environment.

The system’s camouflage capabilities aren’t limited to visible colors though.

By pumping heated or cooled liquids into the channels, researchers can camouflage the robots thermally (infrared color). Other tests described in the Science paper used fluorescent liquids that allowed the color layers to literally glow in the dark.

Just as animals use color change to communicate, there are envisions about robots using the system as a way to signal their position, both to other robots, and to the public. As an example, the possible use of the soft machines during search and rescue operations following a disaster. In dimly lit conditions a robot that stands out from its surroundings (or even glows in the dark) could be useful in leading rescue crews trying to locate survivors.

Going forward, researchers hope to explore more complex systems that use multiple color layers to achieve finer control over camouflage and display colors, as well as ways to create systems — using valves and other controls — that  the robots to operate autonomously.

 Future Applications

For defense applications, ingenuity and efficiency are not enough—robotic systems must also be cost effective. This novel robot is a significant advance towards achieving all three goals.”

In the video above, a soft robot walks onto a bed of rocks and is filled with fluid to match the color of the rocks and break up the robot’s shape. The robot moves at a speed of approximately 40 meters per hour; absent the colored fluid, it can move at approximately 67 meters per hour.

Future research will focus on smoothing the movements; however, speed is less important than the robot’s flexibility. Soft robots are useful because they are resilient and can maneuver through very constrained spaces.

For this demonstration, the researchers used tethers to attach the control system and pump pressurized gases and liquids into  the robot. Tethered operation reduces the size and weight of such robots by leaving power sources and pumps off-board, but future prototypes could incorporate that

equipment in a self-contained system.

At a pumping rate of 2.25 milliliters per minute, color change in the robot required 30 seconds. Once filled, the color layers require no power to sustain the color.

Aside from their potential tactical value, soft robots with microfluidic channels could also have medical applications. The devices could simulate fluid vessels and muscle motion for realistic modeling or training, and may be used in prosthetic technology.

The system might one day have applications ranging from helping doctors plan complex surgeries to acting as a visual marker to help search crews following a disaster