Wearable Electronic Device Performs Sensory Tasks Much Like Real Skin

A new, wearable electronic device being developed by a group of scientists from the University of Colorado Boulder is “really wearable.” This device is a stretchy circuit board that can be fully recycled, and is inspired by, and adheres to, the human skin.

Headed by Jianliang Xiao and Wei Zhang, the researchers have described it as a novel “electronic skin” in an article that was recently published in the Science Advances journal. The device is capable of healing on its own, just like the real skin. In addition, the electronic device can consistently perform a variety of sensory tasks, ranging from quantifying the users’ body temperature to monitoring their day-to-day step counts.

The device can also be reconfigured, which means it can be molded to fit anywhere on the human body.

If you want to wear this like a watch, you can put it around your wrist. If you want to wear this like a necklace, you can put it on your neck.

Jianliang Xiao, Associate Professor, Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder

Xiao and his collaborators are hoping that their latest development will help re-visualize the potential of wearable devices. According to the researchers, such advanced skin material could someday enable people to acquire precise information about their bodies, while reducing the world’s increasing amounts of electronic waste.

Smart watches are functionally nice, but they’re always a big chunk of metal on a band. If we want a truly wearable device, ideally it will be a thin film that can comfortably fit onto your body.

Wei Zhang, Professor, Department of Chemistry, University of Colorado Boulder

Stretching Out

Such thin and comfortable films have traditionally been a staple of science fiction. Imagine the skin peeling off the face of the actor, Arnold Schwarzenegger, in the famous Terminator film franchise.

“Our research is kind of going in that direction, but we still have a long way to go,” added Zhang.

But the goals of Zhang’s research team are both human and robot. The investigators have already explained their design for electronic skin back in 2018. However, their new version of the technology makes plenty of enhancements on the idea —for example, it is relatively more elastic and, at the same time, is also functional.

To produce their bouncy product, Xiao and his collaborators used screen printing to generate a web of liquid metal wires. Then, they closely packed those circuits in between a pair of thin films designed from a self-healing and highly flexible material, known as polyimine.

The device, thus obtained, is slightly thicker when compared to a Band-Aid and can be placed on the skin using heat. The device can even stretch by 60% in all directions without affecting the internal electronics, reported the team.

“It’s really stretchy, which enables a lot of possibilities that weren’t an option before,” added Xiao.

The electronic skin developed by the researchers can do most of the same things that are done by well-known wearable fitness devices, such as Fitbits—that is, consistently measuring the body temperature, movement patterns, heart rate, among many other things.

Less Waste

Arnold Schwarzenegger may want to take note: The researchers’ artificial epidermis is also considerably resilient.

Zhang added that if individuals cut a patch of electronic skin, all they have to do is pinch the broken regions collectively. And within a matter of a few minutes, the bonds holding the polyimine material together will start to reform. In less than 13 minutes, the damage will be virtually imperceptible.

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.

Wei Zhang, Professor, Department of Chemistry, University of Colorado Boulder

Xiao further added that the new study represents a novel method for producing electronics—one that may be relatively better for the Earth.

By next year, that is, by 2021, estimates indicate that human beings will have created more than 55 million tons of discarded laptops, smartphones, and other electronics.

But the stretchy devices developed by Xiao’s team have been developed to skip the landfills. If one of these patches is immersed in a recycling solution, the polyimine will separate into its component molecules, or depolymerize, while the components of the electronics will sink to the bottom. The stretchy material as well as the electronics can be subsequently reused.

“Our solution to electronic waste is to start with how we make the device, not from the endpoint, or when it’s already been thrown away,” added Xiao. “We want a device that is easy to recycle.”

The electronic skin designed by the researchers is still far away from being able to contend with the actual thing. Currently, such devices will work only when they are linked to an external source of power. However, Xiao added that his team’s study indicates that cyborg skin might soon become a fashion trend of the future.

“We haven’t realized all of these complex functions yet. But we are marching toward that device function,” Xiao concluded.

Other CU Boulder co-authors on the latest study include Chuanqian Shi, a former visiting scholar; Zhanan Zou, a former graduate student; Zepeng Lei, a graduate student; and Pengcheng Zhu, a visiting scholar.

Journal Reference:

Shi, C., et al. (2020) Heterogeneous integration of rigid, soft, and liquid materials for self-healable, recyclable, and reconfigurable wearable electronics. Science Advances. doi.org/10.1126/sciadv.abd0202.