Skin-mounted electronic device can sense what’s going on in the body

In a study published in the journal Science, University of Illinois researchers stated that a super-thin skin patch could be used to detect what is going on within the body. The device has an assortment of electronic parts that can sense and communicate with the diagnostic device, and the patch holds on to the skin like a temporary tattoo.

John A. Rogers, team leader, said that the circuit within the patch is flexible, stretches with the skin, and wrinkles without loss of its function. The patch comprising a thin, rubbery substrate mounts an assortment of electronic parts including radio frequency capacitors, transistors, conduction coils, wireless antennas, solar cells for power, sensors, and LEDs.

Rogers said, “We threw everything in our bag of tricks onto that platform, and then added a few other new ideas on top of those, to show that we could make it work.”

Just how a temporary tattoo is applied, the patch is mounted on a thin sheet of water-soluble plastic and then laminated to human skin with water.

Co-leader, Todd Coleman said: “We think this could be an important conceptual advance in wearable electronics, to achieve something that is almost unnoticeable to the wearer. The technology can connect you to the physical world and the cyberworld in a very natural way that feels very comfortable.”

According to the authors, skin patches can have several biomedical applications including EEG or EMG sensors to examine nerve and muscle activity. They have the advantage of not having patient inconveniencing techniques like skin-penetrating pins, conductive gel, bulky wires, or tape, which restrict coupling efficiency.

Compared to conventional electrodes that restrict complete freedom of movement, skin patch are far less burdensome and more convenient for the patient, say the authors.

University of California, San Diego-based Coleman said: “If we want to understand brain function in a natural environment, that’s completely incompatible with EEG studies in a laboratory. The best way to do this is to record neural signals in natural settings, with devices that are invisible to the user.”

In a natural environment, patches enable easy and continuous monitoring of the patient for wellness, cognitive state, health, and numerous bodily functions and routine habits, such as behavioral patterns during sleep. For instance, an ALS patient can conveniently communicate or interface with computers by using a skin-mounted electronic device.
The sensors have the ability to differentiate muscle movements for simple speech when applied to throat, as discovered by researchers. Further, a potential human-computer interfacing ability was demonstrated when researchers used the electronic patches to control a video game.

Rogers said, “Our previous stretchable electronic devices are not well-matched to the mechanophysiology of the skin. 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.”

A team of engineers, led by Yonggang, from Northwestern University and scientists from Illinois joined forces with each other to overcome problems related to mechanics and materials. The team designed device geometry to incorporate the circuits as miniscule, squiggled wires called filamentary serpentine for a range of devices. Consequently, the snakelike wavy shape can bend, coil, and, crease with no loss of functionality when located on a soft, thin rubber sheet.

Huang said, “The blurring of electronics and biology is really the key point here. 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.”
The authors commented that straightforward versions of the technology used in the semiconductor industry enabled effortless manufacture and scaling up of patches. Rogers co-founded a company called mc10 that is presently working on commercializing certain versions of this technology.

The device will soon be Wi-Fi enabled, as researchers plan to include this feature in order to amalgamate everything in it to facilitate the combined, rather than individual, functioning of all components and circuits.
Rogers said: “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.”