Human interactions with robots could soon be revolutionised with ‘skin-inspired’ electronics.
Chemical engineers at Stanford have already discovered a groundbreaking way to create an elastic light-emitting polymer.
Now they have developed stretchy colour displays which could transform the way users interact with TVs, smartphones and other electronic devices.
Zhenan Bao and her research team at Stanford have been working on skin-inspired electronics that are soft and stretchy. Now they have shown proof of principle towards a stretchable, potentially reshapable display in a paper published recently in Nature.
Their invention hinges on the discovery of a method to produce a high-brightness elastic light-emitting polymer, which functions like a filament in a lightbulb. The group’s resulting display is made entirely of stretchy polymers – synthetic plastic materials. The device has a maximum brightness at least two times that of a cellphone and can be stretched up to twice its original length without tearing.
“Stretchable displays can allow a new way of interactive human-machine interface,” said Bao, the K. K. Lee Professor in the School of Engineering and senior author of the paper. “We can see the image and interact with it, and then the display can change according to our response.”
About three years ago, however, postdoctoral scholar Zhitao Zhang discovered that a yellow-colored light-emitting polymer called SuperYellow not only became soft and pliable but also emitted brighter light when mixed with a type of polyurethane, a stretchy plastic.
“If we add polyurethane, we see SuperYellow form nanostructures,” said Zhang, the first author of the study. “These nanostructures are really important. They make the brittle polymer stretchable, and they make the polymer emit brighter light because the nanostructures are connected like a fishnet.”
Unlike adding rubber, the interconnected net of nanoscale fibers that make the SuperYellow stretchy don’t inhibit electricity flow – which is key to developing a bright display. After this discovery, the group also created elastic red, green and blue light-emitting polymers.
While it was challenging to figure out the right materials to match electronically for high brightness and stretchability, the final display now contains seven layers which work together to produce a photon – a particle of light.
The resulting all-polymer film can be adhered to an arm or finger and doesn’t rip during bending or flexing. This will allow wearable trackers to have their display directly attached to the skin.
Bao sees a variety of additional potential uses for a stretchable display. It could be used to produce reshapable interactive screens or even form three-dimensional landscapes on a map.
“Imagine a display where you can both see and feel the three-dimensional object on the screen,” she said. “This will be a completely new way to interact with each other remotely.”
