'Electronic skin' offers cheap, eco-friendly alternative to wearable devices

The flexible electronic skin developed by scientists at the University of Colorado can be fitted to a variety of body parts. Photo by Chuanqian Shi
The flexible electronic skin developed by scientists at the University of Colorado can be fitted to a variety of body parts. Photo by Chuanqian Shi

Nov. 6 (UPI) -- Scientists at the University of Colorado, Boulder, have developed a thin and flexible wearable circuit board that could replace wearable devices. The new e-skin, described Friday in the journal Science Advances, is cheap to produce and fully-recyclable.

Inspired by real skin, the new technology is also self-healing and can perform an array of sensory tasks, from tracking steps to measuring a heartbeat.


Researchers suggest the circuit board's thinness and flexibility allow it to easily be reshaped to form to variety of places on the body.

"If you want to wear this like a watch, you can put it around your wrist," Jianliang Xiao, an associate professor of mechanical engineering at Boulder, said in a news release. "If you want to wear this like a necklace, you can put it on your neck."

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According to Xiao, the new technology's most important attributes are its recyclability and thinness.

"Smart watches are functionally nice, but they're always a big chunk of metal on a band," said Wei Zhang, a professor of chemistry at Boulder. "If we want a truly wearable device, ideally it will be a thin film that can comfortably fit onto your body."


The new e-skin is the latest iteration of a technology Xiao and Zhang have been working on for several years. The latest version is more flexible and functional than the wearable circuit they unveiled in 2018.

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Researchers created the new wearable circuit by screen printing a network of liquid metal wires, before sandwiching the tech between two layers of a super flexible, self-healing material called polyimine.

The e-skin can be stretched up to 60 percent without interfering with the circuitry.

"It's really stretchy, which enables a lot of possibilities that weren't an option before," Xiao said.

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If the e-skin rips, wearers only need to pinch together the torn edge for a few seconds, and within 13 minutes, the material's bonds will reform.

"Those bonds help to form a network across the cut. They then begin to grow together," Zhang said. "It's similar to skin healing, but we're talking about covalent chemical bonds here."

The technology's most important attribute may be its recyclability. With Earth always facing a plastic pollution crisis, the rise in the production and use of wearable devices threatens to exacerbate the problem of plastic and electronic waste.

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When plunged into a a recycling solution, the new e-skin depolymerizes, allowing the electronic wires to sink to the bottom. The stretchy polyimine layers and metal circuitry can be collected and reused.


The e-skin isn't quite ready for primetime, though. Researchers say it still requires an external power source, but they hope to soon integrate a self-powering mechanism.

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