Mood robots may be something that may be in our futures. Scientists have created super elastic electroluminescent "skin" that can change colors and even react to a person's mood. The new robotic skin could be huge when it comes to making robots that are more user friendly.

The hyper-elastic light-emitting capacitor (HLEC) can endure more than twice the strain of previously tested stretchable displays. It consists of layers of transparent hydrogel electrodes sandwiching an insulating elastomer sheet. The elastomer changes luminance and capacitance, which is the ability to store an electrical charge, when stretched, rolled and otherwise deformed.

"We can take these pixels that change color and put them on these robots, and now we have the ability to change their color," said Rob Shepherd, assistant professor of mechanical and aerospace engineering at Cornell University. "Why is that important? For one thing, when robots become more and more a part of our lives, the ability for them to have emotional connection with us will be important. So to be able to change their color in response to mood or the tone of the room we believe is going to be important for human-robot interactions."

In addition to its ability to emit light under a strain of greater than 489 percent its original size, the HLEC is also capable of being integrated into a soft robotic system. Three six-layer HLEC panels are bound together to form a crawling soft robot, with the top four layers making up the light-up skin and the bottom two acting as the pneumatic actuators.

These bottom chambers were alternately inflated and deflated and created an undulating "walking" motion.

"This material can stretch with the body of a soft robot, and that's what our group does," said Shepherd. "It allows robots to change their color, and also allows displays to change their shape."

In all, the electroluminescent skin can stretch to more than six times its original size while emitting light. This discovery could lead to significant advances in health care, transportation, electronic communication and other areas. As robotics continue to improve and continue to enter our daily lives, having a means to make these robots more user-friendly is crucial - and the electroluminescent skin accomplishes just that.