FRIDAY, Aug. 12 (HealthDay News) -- An ultrathin epidermal electronic system (EES), comparable to skin, can effectively monitor the electrical activity of heart, brain, and skeletal muscle when laminated onto the skin like a temporary transfer tattoo, according to a study published in the Aug. 12 issue of Science.
Dae-Hyeong Kim, Ph.D., from the University of Illinois at Urbana-Champaign, and colleagues report on an EES that achieves thickness, elasticity, stiffness, and real mass densities comparable to the epidermis, and measures electrical activity of heart, brain, and skeletal muscles. The EES incorporates electrophysiological, temperature, and strain sensors, transistors, light-emitting diodes, photodetectors, radio frequency inductors, capacitors, oscillators, and rectifying diodes. Solar cells and wireless coils provided power supply.
The investigators note that mechanical properties of the EES depend on the effective modulus and thickness of circuits, sensors, and the silicon-on-wafer substrate. The EES is mounted on a water-soluble film of polyvinyl alcohol against the skin, with electronics facing down. It attaches to the skin through van der Waals forces alone, with negligible mass or mechanical loading effects. All materials coming in direct contact with the skin are biocompatible, and produce no irritation after 24 hours of use. The EES mounted on the chest provides high-quality echocardiograph recordings on all phases of the heartbeat. Electromyography measured on the leg muscles was similar to that recorded by bulk tin electrodes, which require conductive gels and mounting with tape. The EES mounted on the forehead gives high-quality electroencephalography data, and on the throat, it noninvasively monitors muscle activity during speech.
"The materials and mechanics ideas presented here enable intimate, mechanically 'invisible,' tight, and reliable attachment of high-performance electronic functionality with the surface of the skin in ways that bypass limitations of previous approaches," the authors write.
One author disclosed financial ties with MC10, which commercializes biointegrated devices. One or more provisional patents are being filed on this work.