Dye-filled microchannels help machine blend in, or stick out

By Meghan Rosen

Web edition: August 16, 2012
Print edition: September 22, 2012; Vol.182 #6 (p. 9)

Go Go Gadget Camouflage!

A soft-bodied robot with silicone skin and colorful veins can blend into its surroundings — or stick out. Pumping dyes through tiny canals just underneath the synthetic skin helps disguise or reveal the rubbery robot, researchers report  in the Aug. 17 Science.

Layers of the color-changing silicone skin could be glued to robots for search and rescue missions, where tracking and locating machines is key. The dye-filled microchannels, which are about half as wide as a paper clip wire, could also help prosthetic devices look more natural by matching a limb’s coloring to a new summer tan, says study coauthor Stephen Morin of Harvard University. The technology may also end up concealing machines used in combat: The project was funded by the Pentagon’s DARPA and the U.S. Department of Energy.

The work “does a nice job showing that you can create camouflage using a simple technique that is quite effective,” says electrical engineer Jason Heikenfeld of the University of Cincinnati.

Morin and colleagues draped their robot — a translucent X-shaped machine about the size of a smartphone — in a floppy layer of microchannel-threaded silicone rubber that feels like the squishy caulking material used for sealing bathtubs. Then, the researchers pushed compressed air through the robot’s body to walk it onto a rock bed, a patch of leaf-strewn cement or a tiled floor.

Injecting dyes into the rubber layer’s channels camouflaged the robot on the different surfaces or made it stand out, depending on the colors that the researchers mixed in the lab. Heating or cooling the dyes made the robot visible in the infrared spectrum — bright white for hot fluids, purpley-blue for cool.

“If you’re working in a cluttered, poorly lit environment, temperature-controlled solutions could let you pick up the robot’s location with infrared technology rather than using a standard video camera,” Morin says. To switch color schemes, researchers flushed the channels with water then filled them up with new dyes.

But the robot isn’t quite ready for its first mission: It’s still tethered to a pumping station and power supply by long skinny tubes. Morin imagines that future versions of the robot will be large and sturdy enough to carry their own equipment. Eventually, the robots might even haul their own control systems for detecting and matching patterns. For now, though, Morin thinks the taillike tendrils could be an advantage: The tubes allow small robots to creep along unencumbered by extra onboard hardware.

Coupling colored displays with soft robotics is usually tricky because conventional electronic methods use rigid plastics that don’t move well with flexible machinery. The fill-and-flush microchannel technique shows that you don’t necessarily need something as sophisticated as an iPad screen to change a robot’s color, Heikenfeld says.