The research team, including senior author Yonggang Huang of the Departments of Civil and Environmental Engineering and Mechanical Engineering at Northwestern, publish the details of their creation in the journal Nature Communications.
Around 5 cm2 in size, the device consists of up to 3,600 liquid crystals organized on a thin, soft and flexible substrate that can be placed directly on the skin.
According to Huang, the device is "mechanically invisible," noting that its thinness and flexibility makes it "much like the skin itself."
"The device is very practical. When your skin is stretched, compressed or twisted, the device stretches, compresses or twists right along with it," adds co-first author Yihui Zhang, assistant professor of civil and environmental engineering at Northwestern.
Crystals detect temperature change, alerting wearer to potential problems
In their study, the researchers tested the effectiveness of the device by placing it on participants' wrists.
The crystals that make up the device, which are 0.5 mm2 each, can sense temperature changes on the skin's surface. This is enabled by a "wireless heating system" that can detect the skin's thermal properties. This system is charged by electromagnetic waves in the air.
The crystals change color to alert the wearer to any temperature adjustments - a warning that something might be wrong.
Algorithms extract the patterns of color from the crystals and, within 30 seconds, translate this information into a health report detailing the wearer's cardiovascular health - determined by blood flow - and skin hydration levels.
The researchers note that the liquid crystal technology used in the device is similar to the infrared technology already used in hospitals. But they say the infrared technology is costly and limited to clinical and laboratory settings. This device, they say, is low-cost and the wearer can be mobile while using it.
Commenting on the creation, study co-author John A. Rogers, a Swanlund Chair and professor of materials science at the University of Illinois, says:
"These results provide the first examples of 'epidermal' photonic sensors. This technology significantly expands the range of functionality in skin-mounted devices beyond that possible with electronics alone."
The team believes the device will be effective for around-the-clock monitoring of both cardiovascular and skin health. Contemplating its potential success, Huang says:
"One can imagine cosmetics companies being interested in the ability to measure skin's dryness in a portable and non-intrusive way. This is the first device of its kind."
Medical News Today recently reported on a study published in the journal ACS Applied Materials & Interfaces, revealing that scientists are working on developing an "electronic skin" that can detect and produce images of small lumps in the breast that could be missed by a clinician when checking for breast cancer.