It might look like a temporary tattoo. But an ultrathin skin patch that U.S. researchers revealed Thursday actually contains an array of electronics that can be used for everything from diagnosing illness to connecting with the Internet.
Engineering researchers at the University of Illinois have created an almost transparent patch that can be loaded with transistors, wireless antennas and solar cells and have a myriad of medical uses.
Like a temporary tattoo, the patch sticks directly onto the skin and can bend, wrinkle and stretch with the skin underneath. The patch doesn't use an adhesive to stick to the skin; instead, it's laminated on with water, similar to a temporary tattoo.
Researchers describing the patch in the Aug. 12 issue of the journal Science, say it can work as well as standard electrodes in measuring brain activity or muscle activity, depending on where it's applied.
But unlike traditional electrodes, the patches don't require conductive gel, tape, or bulky wires, so they are much more comfortable to wear and allow freedom of movement.
The device is currently designed to stay in place for 24 hours but could stay for as long as two weeks.
Electrical and computer engineering professor Todd Coleman, who helped lead the research team that developed the patch, says it could also be used as an EEG, or electroencephalogram. As well, it could offer an unobtrusive way to monitor brain activity, particularly during sleep.
"If we want to understand brain function in a natural environment, that's completely incompatible with EEG studies in a laboratory," Coleman, who is now a professor at the University of California at San Diego, said in a statement.
"The best way to do this is to record neural signals in natural settings, with devices that are invisible to the user."
In addition to gathering data, skin-mounted electronics could also allow wearers to communicate or interface with larger electronic devices or computers.
The group that developed the patch has created other stretchable, flexible devices, but say that creating devices that could move with the skin presented new challenges.
"Our previous stretchable electronic devices are not well-matched to the mechanophysiology of the skin," said John A. Rogers, a professor of materials science and engineering, of chemistry, of mechanical science and engineering, of bioengineering and of electrical and computer engineering.
"In particular, the skin is extremely soft, by comparison, and its surface can be rough, with significant microscopic texture. These features demanded different kinds of approaches and design principles."
They developed something they call filamentary serpentine, in which the circuits for the various devices are fabricated as tiny, squiggled wires. When mounted on thin, rubber sheets, the snake-like shape allows the wires to bend, twist, and stretch while maintaining functionality.
The researchers are now working to integrate the various devices mounted on the patch so that they work together as a system. They also want to add wi-fi capability.
"The vision is to exploit these concepts in systems that have self-contained, integrated functionality, perhaps ultimately working in a therapeutic fashion with closed feedback control based on integrated sensors, in a coordinated manner with the body itself," Rogers said.
