Reliable blood pressure monitoring without cuff or calibration: A new smart ring pomises the impossible
The story, as reported by Bloomberg, does sounds like a fairy tale. A technician from California, who, according to his own account, almost died from undiagnosed hypertension (high blood pressure), founded a startup dedicated to revolutionizing blood pressure monitoring and launched the Signal Ring roughly three years later. Many wearable manufacturers advertise blood pressure measurements without traditional upper-arm cuffs, but aside from the Huawei Watch D2 and similar products that feature an inflatable cuff around the wrist, virtually all of them must be regularly calibrated using traditional blood pressure monitors.
So even in 2026, almost everyone suffering from high or fluctuating blood pressure will be using technology that ultimately dates back to the 19th century. According to Vital Signal CEO Tom Moss, blood pressure readings obtained using conventional methods also tend to be unreliable because they are highly dependent on the situation and can be skewed by factors such as wearing the cuff incorrectly, nervousness, or drinking coffee before the measurement.
Round-the-clock monitoring
This is exactly where the new Signal Ring comes in, as it not only offers real-time, 24 hour monitoring—including during your sleep—but also targeted blood pressure measurements under more controlled conditions, which Vital Signals calls “Zen Mode.” The data is sent to an Android or iOS app, and can also be synchronized with Google Health or Apple Health. What we find difficult to understand is exactly why the measurements are supposed to be more accurate than those from other manufacturers using PPG sensors (photoplethysmography). Neither Bloomberg nor the brand-new Signal Ring product page provides any technical deep dive into this.
Manufacturer promises greater accuracy
No cuff and no calibration—the manufacturer clearly promises both on its website. According to the information provided, this is possible thanks to a sensor that is four to five times faster than those in competing products, offering higher resolution and allows to extract more details from the measured heart rate data. Building on this, proprietary algorithms are designed to determine accurate blood pressure readings. More details can be found in this blog article. Whether all of this is true remains unclear, as Bloomberg mentions incorrect measurement results during a brief hands-on test, potentially due to rings that didn’t fit properly.
Medical study at universities
Another interesting point in the Bloomberg article is a reference to an ongoing study at four U.S. universities, including Stanford. The background to this is apparently that, in addition to the consumer version of the Signal Ring currently available for pre-order, a medically validated version is also planned, which will then be suitable for diagnosing hypertension. Conversely, this means that the currently available version is likely not intended for that purpose.
Available for pre-order in the U.S.
Anyone who still wants to experience the “future of blood pressure monitoring” right now can pre-order the Signal Ring on the manufacturer’s website for $399. The smart ring is scheduled to ship in October, initially exclusively in the U.S. A sizing kit containing sizes 5–13 will be shipped later this month. The IP68-rated dust- and water-resistant Bluetooth LE wearable offers 5 days of battery life with the charging case. The app does require constant cloud connection for data analysis, however, according to the CEO, a subscription model will never be introduced “as long as cuff-based devices don’t have one either.”
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