A super-thin skin patch that mounts onto the skin like a temporary tattoo has an array of electronic components that can sense what is going on in the body and communicate with diagnostic equipment, researchers from the University of Illinois revealed in the journal Science.
Team leader, John A. Rogers, explained that the patch’s circuit is bendable, it wrinkles and stretches with the skin, without undermining its function. The patch has an array of electronic components which are mounted on a thin, rubbery substrate and includes transistors, radio frequency capacitors, wireless antennas, conduction coils, solar cells for power, LEDs and sensors.
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.”
Firstly, the patch is mounted onto a thin sheet of water-soluble plastic, and is then laminated to human skin with water – in much the same way one would apply a temporary tattoo. In fact, the components could be directly applied to a temporary tattoo itself, making it virtually unnoticeable.
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.”
There are several possible biomedical applications for the skin patch, the authors explained, they could be used as EMG or EEG sensors to monitor muscle and nerve activity. They don’t require conductive gel, skin-penetrating pins, bulky wires, or tape, which are not only uncomfortable for the patient, but also limit coupling efficiency.
The authors say the skin patch is much less cumbersome and more comfortable for the patient than traditional electrodes – he/she has complete freedom of movement.
Coleman, who now works at the University of California in San Diego, 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.”
Monitoring the patient in a natural environment makes it easier to do so continuously, for cognitive state, wellness, health, and several bodily functions and routine habits, such as behavioral patterns during sleep.
A patient with ALS could use a skin-mounted electronic device, such as this skin patch to communicate or interface with computers.
The researchers found that, when applied to the skin of the throat, the sensors could distinguish muscle movement for simple speech. The researchers have even used the electronic patches to control a video game, demonstrating the potential for human-computer interfacing.
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.”
The Illinois scientists collaborated with engineers from Northwestern University, led by Yonggang Huang to overcome some problems with mechanics and materials. They developed a device geometry in which the circuits for various devices are fabricated as miniscule, squiggled wires – known as filamentary serpentine. When placed onto thin, soft rubber sheet, the snakelike wavy shape can bend, twist, and scrunch without losing any functionality.
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 say the patches are easy to scale and manufacture, because they used simple adaptations of techniques used in the semiconductor industry. mc10, a company co-founded by Rogers, is currently working on a way to commercialize some versions of this technology.
The researchers plan to add Wi-Fi capability to the device, as well as integrating everything in it so that all components and circuits can work together as a system, rather as individually.
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.”
Written by Christian Nordqvist