Researchers have recently created an electronic skin — e-skin, for short — that’s malleable, self-healing, and fully recyclable. The idea is to make electronics more environmentally friendly and reduce the amount of e-waste people create by throwing away devices that have been cracked or otherwise aesthetically damaged.
Developed by scientists at the University of Colorado Boulder, the e-skin takes the form of a thin, semi-transparent material that can mimic both the functional and behavioral properties of actual human skin. While it’s intended to give prosthetics the ability to provide sensory feedback to their users, the technology has also been touted for its potential among robots. More specifically, the e-skin could allow robots to experience human sensations by way of touch. These sensations are triggered by sensors embedded in the skin, which themselves will be able to gauge temperature, pressure, humidity, and airflow.
The e-skin boasts several unique properties, including its incorporation of polyimine, a polymer base known for its strength and electric conductivity. It also contains silver nanoparticles for chemical stability. When compounds found in ethanol are mixed with these materials, the e-skin is able to miraculously repair itself. On top of that, it’s completely recyclable — which is exactly why researchers are saying this material is so unique.
“What is unique here is that the chemical bonding of the polyimine we use allows the e-skin to be both self-healing and fully recyclable at room temperature,” says Jianliang Xiao, the mechanical engineer at UCB who led the study. “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 benefit of the e-skin is that it can easily conform to curved surfaces like robotic arms and hands. All one has to do is apply moderate heat and pressure to it without introducing any excessive stresses. If the e-skin is wrapped around a prosthetic hand, it will allow the prosthetic to sense for pressure when picking up an object, such as a glass of water. The skin would then tell the hand how much pressure to use, thereby preventing people from accidentally crushing the cup.
“If you think about what real skin can do, real skin can prevent people getting burned [and] can prevent people getting hurt,” says Wei Zhang, a chemistry professor at the university and the co-author of the study. ”E-skin can basically mimic those [preventative] functions. At least that’s one big part of the electronic skin.”
Should robots ever have to handle babies in some capacity, they would find the e-skin immensely helpful, as it would allow them to feel out the appropriate pressure and temperature. “Sensing is critical because when human beings interact with robots, we want to make sure that robots don’t hurt people,” Xiao explains. “When the baby is sick, the robot can just use a finger to touch the surface. [Then] it can tell what the temperature of the baby is.”
He adds: “I think we are the first group to demonstrate recycling of such multifunctional e-skin.” To recycle the skin, it must be soaked in recycling solution, which causes the polymers to degrade into smaller molecules like oligomers and monomers. “The recycled solution and nanoparticles can then be used to make new, functional e-skin. What drives us to make such devices to be recyclable is because, nowadays, we are facing very serious environmental pollution due to tens of millions of tons of electronic waste.”