This Thin, Flexible Sensor Tracks Blood Flow Under The Skin


Testing blood flow is currently a rather tedious task, with patients having to be at a clinic, then having to sit as still as possible during the imaging process. A new experimental sensor, however, could help make testing blood flow much easier.

The sensor, developed by researchers at the University of Illinois at Urbana-Champaign, acts like a temporary tattoo, and it enables blood to be tracked for a 24-hour period while the patient continues doing his or her daily tasks. Not only that, but the sensor is flexible, meaning that it stays on the skin and out of the way during the day.

The new epidermal sensor doesn't just help make testing blood flow easier, but it could also offer more accurate results. Current methods essentially provide a snapshot of blood flow over a short period of time, but tracking blood flow over an entire day will help doctors see what the patient's blood flow is like at different times of the day. The sensors are able to measure blood flow in the outermost 1 to 2 millimeters of skin, even when the patient is moving.

"Say you have diabetic patients and want to be able to monitor changes in specific blood vessels continuously for 24 hours a day," says Richard Chad Webb, a graduate student in materials science and engineering at the University of Illinois, in an interview with Spectrum, the magazine of the IEEE. "There's no way of doing that today."

Most of today's blood flow sensors use optical imaging technology that requires patients to stay very still. Instead of using optical imaging, however, Webb and his team turned to flexible electronics. The lightweight and ultrathin device sticks to the skin without distorting blood flow. The sensor itself is made from a 40-micrometer thick layer of silicone, which is the layer that holds most of the electronics. The rest of the layers of the device are only tens or hundreds of nanometers thick.

To sense blood flow, the sensor basically looks at differences in heat patterns caused by blood below the skin, with a 1.5-millimeter thermal actuator in the device actually heating up by around 6 or 7 degrees Celsius to offer a thermal background for the measurements. That's not enough temperature difference to make it noticeable to the wearer, researchers note.

Of course, there is a lot more testing to do before the device will be available for purchase. The team, for example, still needs to find a way to build a version of the device with a self-contained power source that is able to wirelessly transmit data.

Webb was lead author of a paper about the research that ran in the journal Science Advances.

Via: Spectrum

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