The last time you had your blood pressure checked, it was probably at a doctor’s office with a bulky cuff wrapped around your arm. One day soon, perhaps, you will just need a simple stick-on patch on your neck, no bigger than a postage stamp.
That’s the goal of Sheng Xu and his team at the University of California, San Diego, who are working on a patch that can continuously measure someone’s central blood pressure—the pressure of blood coursing beyond your aorta, the artery in your heart that delivers blood to all the different parts of the body. It could make it a lot easier to monitor heart conditions and keep an eye on other vital organs like the liver, lungs, and brain.
The silicon elastomer patch works by sending out ultrasonic waves that penetrate the skin and reflect off the wearer’s tissues and blood. Those reflections are sent back to the sensor, and then to a laptop that processes the blood pressure data (for now, at least, the patch must be wired to a laptop and a power source, too). It is the first known wearable device that can sense deep below the surface of the skin. In theory, the patch could be used at home to monitor patients over time. And because it’s not inserted into the body, there’s no risk of infection.
“You can’t wear a blood pressure cuff all the time,” Xu says.
The device can provide a lot more information than you can get with a standard blood pressure cuff. This information, Xu believes, can be useful for keeping an eye on patients with conditions like hypertension or a history of heart attack. The patch can be placed right near the jugular vein, it can measure how much blood is streaming into the heart. That might make it helpful for spotting whether someone is dehydrated, he says.
“It could turn out that central blood pressure has more predictive value in terms of outcomes in the future, but as of now we don’t have that much data,” he says.