Are you ready for soft, morphing, crawling robots with glowing skin displays?

Turn and face the strange.
March 11, 2016

Multi-pixel electroluminescent displays in various states of deformation and illumination (credit: C. Larson et al./Science)

Your future robot or mobile device could have soft, morphable, stretchable “skin” that displays information, according to research by Cornell University engineers. Imagine a health-care robot that displays your blood glucose level and oxygenation, and even your mood — perhaps also your remote physician’s face in 3D.

“When robots become more and more a part of our lives, the ability for them to have an emotional connection with us will be important,” says research team leader Rob Shepherd, an assistant professor of mechanical and aerospace engineering.

Soft robots are currently in use for safe human robot interaction, but they can’t stretch continuously or dynamically display information on their body; and in most cases, can’t sense external and internal stimuli. So the engineers have developed octopus-inspired electroluminescent “skin” that stretches to more than six times its original size, and can also change shape and color.

An undulating gait produced by pressurizing the chambers in sequence along the length of the crawler (credit: C. Larson et al./Science)

The new technology uses a “hyper-elastic light-emitting capacitor” (HLEC), consisting of layers of transparent hydrogel electrodes sandwiching an insulating elastomer (a polymer with viscoelasticity, meaning it has both viscosity and elasticity) sheet.

The elastomer changes luminance and capacitance (the ability to store an electrical charge) when stretched, rolled, and otherwise deformed.

The HLEC skin also endows soft robots with the ability to sense their actuated state and environment and communicate optically — and (for small robots) even crawl.

The engineers created a prototype crawling soft robot, using three of the six-layer HLEC panels bound together. The top four layers made up the illuminated skin and the bottom two served as pneumatic actuators. The chambers were alternately inflated and deflated; the resulting curvature created an undulating, walking motion.

It could also make for a fun pet, we’re guessing.

The team’s research was published in the March 3 online edition of the journal Science. It was supported by a grant from the Army Research Office, a 2015 award from the Air Force Office of Scientific Research, and two grants from the National Science Foundation.

Cornell University | Electroluminescent Skin Demonstration

Abstract of Highly stretchable electroluminescent skin for optical signaling and tactile sensing

Cephalopods such as octopuses have a combination of a stretchable skin and color-tuning organs to control both posture and color for visual communication and disguise. We present an electroluminescent material that is capable of large uniaxial stretching and surface area changes while actively emitting light. Layers of transparent hydrogel electrodes sandwich a ZnS phosphor-doped dielectric elastomer layer, creating thin rubber sheets that change illuminance and capacitance under deformation. Arrays of individually controllable pixels in thin rubber sheets were fabricated using replica molding and were subjected to stretching, folding, and rolling to demonstrate their use as stretchable displays. These sheets were then integrated into the skin of a soft robot, providing it with dynamic coloration and sensory feedback from external and internal stimuli.