Self-Healing Electronic 'Skin' Lets Amputees Sense Temperature And Pressure On Prosthetic Limbs

Biomedicine just took another leap forward. University of Colorado Boulder scientists created so-called electronic skin—e-skin for short. The e-skin is a thin, semi-transparent material that can act like your skin through measuring temperature, pressure, humidity and air flow. The new material, which was detailed in a study published Friday in Science Advances, could make better prosthetics, improve the safety of robots in the future and aid development of other biomedical devices.

"This has quite broad applications, in a sense, to enable sensation of otherwise passive systems," Jianliang Xiao, mechanical engineer at Boulder who led the study, told Newsweek. Those passive systems are the electronic devices we use, but which don't have the same capabilities that our skin naturally has.

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This e-skin has the ability to sense for pressure, which is a key factor for improving prosthetic limbs. For instance, if the e-skin is wrapped around a prosthetic hand, the e-skin would enable the prosthetic to sense for pressure when holding a glass cup. Knowing how much pressure the mechanical hand is applying could prevent a person using it from accidentally crushing the cup, Xiao explained.

"If you think about what real skin can do, real skin can prevent people getting burned [and] can prevent people getting hurt," Wei Zhang, a chemistry professor at Boulder and co-author of the study, told Newsweek. "E-skin can basically mimic those [preventative] functions. At least that's one big part of the electronic skin."

The e-skin also has applications for the future of robots. In the future, should robots handle babies in some form, they would be able to feel for 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 said. Robots in the future could be handling a baby and, if the robot can feel for pressure, the robot could handle a baby more safely. Detecting a fever is another benefit.

“When the baby is sick, the robot can just use a finger to touch the surface,” Xiao said. Then, “it can tell what the temperature of the baby is.”

The material is made from a polymer network called polyimine as well as silver nanoparticles, the latter which provide strength, chemical stability and electrical conductivity. Researchers explained that the e-skin can heal itself, just by mixing compounds found in ethanol with the material. Heat and pressure can allow the e-skin to wrap around curved objects easily, such as human skin and intricate robotic hands. Plus, the material is recyclable, which is what researchers say makes their e-skin material unique.

"I think we are the first group to demonstrate recycling of such multifunctional e-skin," Xiao said. E-skin is recycled by soaking the polymers into a solution that degrades the polymers down and separates the silver nanoparticles, which sink down to the bottom of the solution. "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,” he added.

Zhang took the recyclability concept a step further. He sees a future where you can simply soak your cell phone or your laptop in a solution that dissolves the materials down to be reused again. That would be the "dream," he said.