Thin electronic patches on skin could monitor hearts comfortably

The electrode, that staple of hospitals and medical dramas alike, may soon exit stage left. Researchers have designed a wireless electronic monitoring device so thin it can be applied to the skin like a temporary tattoo. It could one day be used to monitor heart, brain and muscle activity of patients without their even noticing.

The research, released Thursday in the journal Science, could rid hospitals of the unwieldy, outdated monitoring systems, which often involve needles, webs of wires and conductive gels.

“Such complicated wiring can be inconvenient and distressing for both patients and physicians,” Zhenqiang Ma, an engineering professor at the University of Wisconsin who was not involved in the research, wrote in a commentary on the study. Patients with heart disease may have to wear bulky monitors for a month to try to catch rare cardiac events, he explained.

A more streamlined, wearable, integrated system would appear to be a relief to all.

But designing a chip flexible enough to stretch, squeeze and twist with the skin is no easy task, said study coauthor John Rogers, a materials scientist with the University of Illinois at Urbana-Champaign.

Silicon, the key ingredient in electronic devices, is very rigid. Manufactured in the form of a relatively thin silicon wafer, he said, “it’s like a plate of glass” and shatters when dropped.

The solution was in the design. The researchers first used extremely thin slices of silicon -- about 50 to 100 nanometers deep -- to increase their flexibility. They used the silicon to create S-shaped chains whose snaky contours were able to conform to skin and layered the structure onto membranes that closely match skin’s properties and movement.

Testing the device, the researchers found that it gave readings for brain, heart and muscle activity just as well as did traditional electrode-based systems.

The chips could even be hidden under conventional temporary tattoos. The researchers demonstrated by mounting the device onto skin underneath a colorful image of a pirate’s head. (Future patients, presumably, would have other aesthetic options.)

The devices stick to the skin’s surface in much the same way geckos are believed to cling to walls, by taking advantage of a phenomenon called the Van der Waals force. But Rogers said that for longer-term adhesion -- or in the event that, say, a patient sweats heavily -- adhesives like those built into temporary tattoos could provide more a durable option.

The technology could also be used for voice-commanded software, Rogers added, by mounting the device on a person’s throat and training it to recognize and transmit simple commands.

Ultimately, the military might have as much interest in this new technology as the medical profession.

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