If you wanted to create a synthetic fabric to cover a humanoid robot, referring to an octopus' stretchy, color-shifting skin might do the trick.
Now, researchers have done just that: creating a soft, three-layered, light-emitting material infused with electronic sensors.
"Our target was to make sensors in the skin so we can feel its external shape and the robot can feel its own shape," said Rob Shepherd, assistant professor of aeronautical and mechanical engineering at Cornell University and an author on the new study coming out today in the journal Science.
"The bonus is that these sensors can also emit light."
Shepherd and graduate student Shuo Li, lead author on the paper, said the new material will more likely be used to display information in an airplane cockpit or on a car's dashboard – rather than building an army of androids.
The researchers say they want to make something called "vanishing interfaces," such as a radio volume control knob that appears and lights up when you need it, then disappears back into the dashboard when finished.
"Think about a cockpit in a jet fighter," Shepherd said. "There are tons of things to see and interact with but maybe not at the same time."
"Being able to have an interface emerge when you need it and then disappear may simplify controls in complex environment."
A sensitive, color-changing robot -- human-shaped or not -- could also be used in a hospital setting to monitor how patients are feeling, for example, as well as measuring and displaying their vital signs at the same time.
Colors are associated with moods, he explained, and having robots display colors will help them communicate with people.
The team, funded by the U.S. Army and U.S. Air Force, put the new skin on an existing "soft robot" built by Shepherd and Li.
The skin consists of two layers of a transparent hydrogel -- (salty water) sandwiching a electroluminescent rubber-like material.
"All three layers form a capacitor," Li said. "By introducing a voltage we can make it emit light. The whole structure is based on soft materials so it is very stretchable."
In fact, the skin can stretch five times its normal size, making it perfect for the disappearing act that Shepherd envisions.
Three six-layer electronic panels were bound together to form a crawling soft robot, with the top four layers making up the light-up skin and the bottom two the pneumatic actuators.
The chambers were alternately inflated and deflated, with the resulting curvature creating an undulating, "walking" motion.
The synthetic "octo-skin" is 5 millimeters thick, with each of the 64 pixels measuring 4 millimeters square.
Michael Tolley, professor of bio-inspired engineering at the University of California, San Diego, said that the study is a step forward in highly stretchable displays and sensors used for soft robots.
"Technological advances like this one will enable engineers to design robotic systems that are increasingly soft and adaptable like biological systems," he said in an e-mail to Discovery News.
"I can imagine this type of display and sensor being used for systems built for human-robot interaction in the context of service robotics, entertainment, or many other applications."