Someday soon, hospital patients won’t be hooked up to wires and monitors — instead, electronic patches will be temporarily tattooed onto their bodies. Doctors will be able to monitor their vital signs without poking and prodding, and patients wearing neck patches will even be able to communicate with robots, who will translate throat muscle movements into simple speech.
A new electronic skin patch, no more invasive than a temporary tattoo, marks a major breakthrough in human-machine interfaces. Tiny semiconductor circuits that stretch with the skin could be rubbed onto a person’s skin to monitor muscle activity, heart activity or even brain waves in real time without using bulky medical equipment.
The epidermal electronic circuit is initially mounted on a super-thin sheet of soluble plastic and laminated onto the skin with water, just like a temporary tattoo. Once it’s on, it can bend, wrinkle and stretch along with a wearer’s skin — it doesn’t pop off or snap, which is no small feat considering this is a high-performance semiconductor. When it’s no longer needed, it peels off like a layer of sunburned skin. Check out the video below to see this in action.
The devices adhere to the skin not with glue or static electricity, but close-contact atomic forces called van der Waals interactions, which are essentially invisible to the user. Adhesion lasts up to 24 hours, the researchers report.
Researchers at the University of Illinois who came up with this device made circuits with a wide array of components, to prove it could work: sensors, LEDs, transistors, radio frequency capacitors and wireless antennas, according to UI. The devices can draw power from induction or even from mini solar cells.
Inventors say they could be used for various medical applications, especially sensors that monitor heart and muscle activity, which currently require conductive gels, tape and wires. To prove it, they measured electrical activity produced by the heart, brain, and skeletal muscles, they report in this week’s issue of the journal Science.
Studying brain function in a normal environment is impossible now — to use an EEG, a patient would have to be in a lab setting or wear some type of complicated helmet — but the patch could make it possible. Or imagine a patient with a degenerative disease who cannot communicate, but could use the patches to connect with a computer.
In a throat patch experiment, the patch was precise enough for the research team to differentiate several words, according to the National Science Foundation. They were even able to control a voice-activated video game with better than 90 percent accuracy.
Peels Right Off
“The technology can connect you to the physical world and the cyberworld in a very natural way that feels very comfortable,” said UI electrical and computer engineering professor Todd Coleman, who co-led the research team.
The circuits are made possible through novel fabrication methods that allow bendable versions of semiconductors that are brittle when in bulk form. The research team, which also included engineering researchers at Northwestern University, developed a new device geometry they call “filamentary serpentine,” according to a UI news release. The circuits of the various devices are fabricated as tiny, squiggled wires, as shown in the photo above. The circuits’ wavy shape allows them to bend, twist, scrunch and stretch while maintaining functionality.
“The blurring of electronics and biology is really the key point here,” said Northwestern engineering professor Yonggang Huang. “All established forms of electronics are hard, rigid. Biology is soft, elastic. It’s two different worlds. This is a way to truly integrate them.”