This smartwatch tracks your blood pressure without a cuff

Blood pressure isn’t a fixed number—it rises and falls all day as you walk, run, or climb stairs. But the standard cuff catches only a single snapshot, usually taken while you sit still. Now an interdisciplinary team of mathematicians and engineers from the University of Utah and the University of Illinois, Chicago, has built a cuffless wearable device that tracks blood dynamics continuously.

The smartwatch, described in Nature Communications, measures both blood pressure and blood flow by reading the electrical properties of blood as it pulses through the artery at the wrist.

“Elevated blood pressure is considered the silent killer because it leads to heart attacks, aneurysms, and strokes,” says UIC’s Benjamin Sanchez Terrones, who hatched the project as a U assistant professor of electrical and computer engineering.

Unlike commercial devices that use light and lean on machine learning as a “black box,” his watch uses a painless electrical current, recording tiny changes through bioimpedance—a measure of how easily electricity flows through blood and tissue. Because the team encoded the physics of blood flow directly into the model, the results are more accurate and interpretable.

“Blood pressure isn’t two numbers; it’s a function of time,” says co-author Braxton Osting, a U professor of mathematics. “Embedding the physics of blood flow directly into the model makes the prediction more trustworthy.”

Graduate students tested the device on 150 people, including outpatient and intensive-care patients.