Researchers at University of Colorado Boulder have developed an electronic skin that can heal itself – and is also fully recyclable. According to the paper published in the journal Science Advances, the e-skin is a thin, translucent material with sensors embedded to mimic function and mechanical properties of human skin such as sensing pressure temperature, humidity and air flow.
The uniqueness about this piece of technology is that it’s made of a polymer called polyimine (made of three commercially available compounds – terephthalaldehyde, diethylenetriamine, and tris(2-aminoethyl)amine – mixed together in ethanol) laced with silver nanoparticles to withstand stress, conduct electricity and provide chemical stability. And what’s more? When the skin is cut in two, polyimine can recreate chemical bonds between two sides – allowing the e-skin to heal itself completely.
“What is unique here is that the chemical bonding of polyimine we use allows the e-skin to be both self-healing and fully recyclable at room temperature,” said Jianliang Xiao, an assistant professor in CU Boulder’s Department of Mechanical Engineering in a news release. “Given the millions of tons of electronic waste generated worldwide every year, the recyclability of our e-skin makes good economic and environmental sense.”
Another cool feature about this e-skin is that you can make it wrap around curve surfaces like human arms and robotic hands by using a modest amount of heat and pressure.
“Let’s say you wanted a robot to take care of a baby,” said Zhang. “In that case you would integrate e-skin on the robot fingers that can feel the pressure of the baby. The idea is to try and mimic biological skin with e-skin that has desired functions.”
Researchers around the world are developing different types and sizes of wearable e-skins. Some of the notable examples are – the one developed in Europe, which allows users to manipulate virtual and physical objects without touching them, and another one (by a Japanese startup, Xenoma), which turns shirt into a video game motion controller. But what makes this new e-skin stands out from the rests is that it’s fully recyclable.
“This particular device … won’t produce any waste,” Xiao told the Verge. “We want to make electronics to be environmentally friendly.”
So if the e-skin is damaged beyond repair, it is soaked into ‘recycling solution’. This solution degrades polymers into smaller molecules that are soluble in ethanol, allowing the silver nanoparticles fall to the bottom of the solution. The left-over materials is then re-used to make another fully functioning e-skin.
Researchers say e-skin could have potential applications in making of prosthetics, robots, or smart textiles – all without having to worry about producing more e-waste. However, Xiao says the e-skin is yet to be perfected, because it’s not as stretchy as human skin. Right now, he and his team are working to improve the device’s scalability.
The study, entitled “Rehealable, fully recyclable, and malleable electronic skin enabled by dynamic covalent thermoset nanocomposite” has been published in the journal Science Advances.