‘Skin-Like' Photonic Device Monitors Cardiovascular Health

By Chuck Seegert, Ph.D.

Heart problems may now be monitored in real-time using a new high-resolution technology that is low-cost and virtually undetectable. These are only a few benefits of the novel advance from University of Illinois researchers.

The skin is subject to many influences in the body. One of these is cardiac performance, which leads to small changes in the temperature and color of the skin as the heart beats. In addition to blood flow, an individual’s hydration level can have an impact on the skin as well, changing its thermal conductivity. While these characteristics can be studied by many methods, this new device promises ease-of-use that may extend benefits to a much wider population.

To gain these benefits, a thin, patch-like device of about 5 cm² must be attached to the skin, according to a recent press release from Northwestern University. The patch is composed of thousands of liquid crystals, each capable of sensing the thermal properties of the skin on a sub-millimeter level. When it changes color, the person wearing it knows something is wrong.

“Our device is mechanically invisible, it is ultrathin and comfortable, much like skin itself,” said Northwestern’s Yonggang Huang, one of the senior researchers, in the press release.

Testing performed by the team was recently published in a study in Nature Communications. The thin film photonic device includes colorimetric indicators for temperature sensing, along with stretchable wireless electronics for other thermal measurements. Using a digital camera, the color changes can be extracted and analyzed quantitatively with certain algorithms the team has developed. According to the study, temperature can be measured with +/- 50 milli-Kelvin accuracy on a sub-millimeter resolution.

“These results provide the first examples of ‘epidermal’ photonic sensors,” said John A. Rogers, the paper’s corresponding author, a Swanlund Chair, and a professor of materials science and engineering at the University of Illinois, in the press release. “This technology significantly expands the range of functionality in skin-mounted devices beyond that possible with electronics alone.”

Using skin reactions to monitor underlying cardiovascular performance is an area receiving a lot of attention from multiple research groups. Recently in an article published on Med Device Online, a webcam test was reported that indicated a patient’s heart health via color changes in the facial region.