There is heart-pumping news from the brave new world of wearable medical devices — a new sensor no thicker than a temporary tattoo can monitor blood flow in real time.

"Continuous monitoring of variations in blood flow is vital in assessing the status of microvascular and macrovascular beds for a wide range of clinical and research scenarios," observed researchers from the University of Illinois in Urbana-Champaign, led by materials engineer Chad Webb, in their just-published article in the journal Science Advances.

"Although a variety of techniques exist, most require complete immobilization of the subject, thereby limiting their utility to hospital or clinical settings," they noted, adding that worse yet, those that can be worn "suffer from limited accuracy, motion artifacts, and other shortcomings that follow from an inability to achieve intimate, noninvasive mechanical linkage of sensors with the surface of the skin."

Their first-ever device has now been shown to overcome these challenges. Its ultra thin, soft and skin-conforming technology allows for "precise blood flow mapping," they stated.

The heart of the device is a sandwich of tiny heat pads and heat sensors all "painted" on a skin made of silicone. This lets the sensor detect the heat of blood in veins, determining the vessel's size and how fast the heat moves, which allows accurate computations to determine blood flow.

This is of particular importance in those conditions in which transient blood flow can be missed during hit-or-miss spot checks by health care personnel.

Blood flow monitoring has a significant impact on health care. Infection and inflammation can boost local blood flow, so the monitor can indicate those conditions. Conversely, atherosclerosis, heart failure, and diabetes, can cause a drop in local blood flow. So for those with these debilitating conditions the chance to monitor blood flow, to limbs for example, can have a considerable impact on disease management and patient well-being, allowing doctors to individualize care to specific patients and conditions.

"Vascular disease motivates a lot of research on blood flow, but the difficulties and limitations of collecting that data" — such as needing people to stay immobile in a lab — "really limit the kinds of questions you can ask," Webb explained to Popular Mechanics magazine. "Collecting this data 24/7 with a wearable device is such a new concept that we don't really know what insights we could gain."

The sensor is not only unobtrusive, it's also very wearable, as motion doesn't cause measurement issues for the most part, thanks to the way it “intimately laminates” to the skin, senior author John Rogers, one of the inventors and a professor of materials science and engineering at the University of Illinois at Urbana-Champaign, told MIT Technology Review.

Interestingly, dermatologists may be among the first professionals to find uses for this new sensor technology, Rogers noted. Cosmetics giant L’Oréal, was one of the funders of his research. The firm has started to make the sensors and created software to do the data analysis to study skin health, he noted.

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