Cuffless Blood Pressure Tracking
US Researchers Develop Smartwatch System for Continuous, Cuffless Blood Pressure Monitoring
Researchers at the University of Utah and the University of Illinois Chicago have built a smartwatch that measures blood pressure continuously — all day long — without ever needing a traditional arm cuff. The study, published May 14 in Nature Communications, tested the device on 165 adults and found mean errors as low as 3.26 mmHg for systolic pressure and 2.12 mmHg for diastolic pressure, figures that approach clinical accuracy.
Lead researcher Benjamin Sanchez Terrones called continuous blood pressure monitoring the "Holy-Grail problem" of engineering. He compared a single doctor's office reading to "trying to guess the plot of a movie from a single screenshot." His team believes the new device could change how the world's 1.3 billion people with high blood pressure manage their condition.
How the Smartwatch Reads Blood Pressure Without a Cuff
Most smartwatches use green light to track heart rate — a method called photoplethysmography, or PPG. PPG-based blood pressure estimates are notoriously unreliable. They are sensitive to skin tone, movement, and ambient light. The new device takes a completely different approach, according to UIC Today.
Instead of light, the watch sends a tiny, imperceptible electrical current through the wrist. The method, called bioimpedance, measures how easily that current travels through blood and tissue. As the heart beats and blood pressure changes, the resistance shifts. A physics-informed AI model — one built on the laws of fluid dynamics and electromagnetism — converts those shifts into real-time blood pressure readings, according to University of Utah.
Calibration-Free Design Is the Real Breakthrough
Existing consumer devices, like the Samsung Galaxy Watch, can estimate blood pressure — but only after the user calibrates them with a real arm cuff every few weeks. That requirement defeats the purpose for anyone without easy access to medical equipment, according to Gadgets & Wearables.
The Utah/UIC watch requires no calibration at all. Co-author Christel Hohenegger, a mathematics professor at the University of Utah, said that "building physical principles directly into the model" allows the system to "move beyond black-box prediction." The University of Utah Technology Licensing Office is already looking for commercial partners to bring the device to market, according to News-Medical.
Current Smartwatch Alerts Miss 59% of Hypertension Cases
In February 2026, a separate University of Utah study published in JAMA revealed a serious gap in today's wearable tech. Roughly 59% of people with undiagnosed high blood pressure would not receive any alert from current optical smartwatch systems, according to University of Utah Health.
Apple received FDA clearance in September 2025 for a "Hypertension Notifications Feature" on its watch. But Apple frames it as a screening tool, not a diagnostic device — a key legal distinction. The American Heart Association warned in December 2025 that most wearables are "not yet proven accurate enough to diagnose high blood pressure or guide treatment decisions," according to the American Heart Association.
A $3.5 Billion Market and a Race Between Rival Technologies
A working calibration-free smartwatch could disrupt the $3.5 billion global blood pressure monitor market, according to News-Medical. The potential savings in prevented strokes and heart attacks make the stakes even higher. Similar research at UT Austin and NC State has already landed a $2.5 million contract from ARPA-H, the US government's health research agency.
Three technologies are now competing to win this market: bioimpedance (Utah/UIC), ultrasound patches (UC San Diego), and radio-frequency waves (UT Austin). UC San Diego's ultrasound patch was validated on more than 100 patients in November 2024. The Utah/UIC team is now preparing a full-scale clinical trial to test its device through real-world conditions — including exercise, sleep, dehydration, and weight change — according to UIC Today.
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