More Than Skin Deep


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An ultrathin, electronic patch with the mechanics of skin can be used for many biomedical applications. Image: Illinois.edu

Imagine someone monitoring your health, making sure you’re physically at your best, 24/7. Welcome to a world made possible by a skin monitor being developed by the University of Illinois and Northwestern University. It may be the size of a small tattoo, but you don’t need a needle to have it applied to your skin. In fact, if all goes according to plan, it may save you from many needles in your medical future.

Moving from Bell Laboratories, where he worked with organic-based semiconductor materials, University of Illinois professor John Rogers is part of a team that was able to incorporate silicon to make it not just stretch but bend. “We were doing it by using principles and buckling mechanics,” says Rogers, who is a professor of materials science and engineering at the school. “It turned a material challenge into a mechanics challenge. The advantage of doing that is you can align the technology with silicon. That opened up a range of applications that were previously impossible in terms of performance requirements. The skin part of the body is a great point of integration and making devices that are skin-like allows you to intimately integrate very advanced semiconductor technology and sensors with the body.”

The patches are initially mounted on a thin sheet of water-soluble plastic. Image: Illinois.edu

Their technology can go on any part of the body, he says, and can be an implantable device as well, possibly even finding uses as a pacemaker or cochlear implant. “By going with the epidermis, it becomes invisible,” he says. “The mechanics actually match to the epidermis so no mechanical constraint, mechanical loading, mass loading, or thermal load on the skin. You don’t know that it’s there so it’s intrinsically a wearable device and the device can adhere to the surface of skin in a reliable way and not peel off.”

According to Rogers, what they’ve created provides a high-precision window for making measurements. “It can measure things such as temperature, hydration state, and subtle changes in the surface displacement of skin associated with bloodflowing and arteries,” he says. “It can measure electrical activity, dealing with the heartbeat and the brain activity.”

It has the capability of an EKG, he says, but without needing to use elements such as gel or a hard electropad to work. “[Their invention is] taking a mesh-type structure and putting on a soft skin application elastomer,” he explains. “The soft elastomer has a natural tacky surface and causes it to wet the surface spontaneously and, as it does, that brings the metal mesh into contact with the skin. It provides something robust on the mechanical side but with low impedance.”

The next level is to use near-field coupling. “All smartphones have a mechanism for doing near field transfer; wireless transfer of data from the phone to a near field type tag,” he says.

Another level they’re looking at is a Bluetooth-style radio communication, their goal being to publish that kind of platform in the spring.

“I’m optimistic that we will have an impact and can drive this forward,” Rogers says. “The likelihood electronics won’t go in this direction seems small. We think this has a chance to be an important positive in health.”

Eric Butterman is an independent writer.

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The likelihood electronics won’t go in this direction seems small. We think this has a chance to be an important positive in health.

Prof. John Rogers, University of Illinois

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October 2014

by Eric Butterman, ASME.org