Scientists' new sticky electronic skin is a greener option for wearable devices

Dispensing with traditional digital monitoring devices you strap onto your wrist or other body part, scientists at the University of Colorado Boulder have just created what could be the next must-have fashionable (and functional) accessory in an invention they call electronic skin.

Able to stretch 60 percent in any direction without compromising its integrity, their wearable electronic epidermis is a thin band of artificial skin infused with a fully-recyclable circuit board to record and keep tabs on vital functions and exercise goals.

Jianliang Xiao and Wei Zhang headed up this sticky project and published the results of their findings last week in the online journal Science Advances. This advanced device is capable of performing a wide range of sensory and medical monitoring functions like body temperature, heart rate, and repetitive movements like step counts. It's also able to adapt to any part of you body and can heal itself similar to real skin.

Credit: Chuanqian Shi

"If you want to wear this like a watch, you can put it around your wrist," explained Xiao, an associate professor in the Paul M. Rady Department of Mechanical Engineering at CU Boulder. "If you want to wear this like a necklace, you can put it on your neck."

Xiao and his team believe their hi-tech skin has the ability to get people thinking more about the nature and capabilities of wearable devices that go far beyond making phone calls, texting, and listening to music. The maleable invention allows for accurate compiling of vital info and reduces the planet's growing pile of electronic gadget garbage. 

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

In producing the rubbery lifelike epidermis, Xiao and his crew make use of screen printing techniques to create a network of liquid metal wires. Those circuits are then stuck between two ultra-thin films made from an extremely flexible, self-healing material known as polyimine. Once complete, the remarkable accessory isn't much thicker than a traditional Band-Aid and conforms to your own skin with the application of heat.

Credit: Chuanqian Shi, Zhanan Zou et al.

"If you slice a patch of electronic skin, all you have to do is pinch the broken areas together," Zhang noted. "Within a few minutes, the bonds that hold together the polyimine material will begin to reform. Within 13 minutes, the damage will be almost entirely undetectable.

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

When Xiao and Zhang's invention can be fully reused after being dipped into a recycling solution, where the polyimine will depolymerize, separating down to its component molecules while the electronic pieces sink to the bottom.

Scientists estimate that by 2021, Mankind will have accumulated more than 55 million tons of tossed-out cell phones, laptops, iPods, smart watches and other assorted electronics.

Credit: Chuanqian Shi

"Our solution to electronic waste is to start with how we make the device, not from the end point, or when it's already been thrown away," Xiao said. "We want a device that is easy to recycle."

Electronic skin is far from replicating Terminator-like synthetic material as this prototype still requires an external power source, but it's a sizable advancement toward creating a new 21st century product line of stretchy digital devices for the future.