Apple Watch Series 10
Blood pressure readings have been rumored for the Apple Watch for several generations now. Serial whistleblower Mark Gurman of Bloomberg claims this year will be the year it actually happens.
A few days ago Gurman reported that the Apple Watch Series 11 and Watch Ultra 3 will have Apple’s long-awaited blood pressure function.
However, there is a reason it has taken so long. And while it will likely be somewhat limited when it arrives.
The classic way to measure blood pressure is with an inflated cuff, part of a kit known as a sphygmomanometer. It is used to determine the pressure of blood flow as that flow is blocked through the inflation of the cuff worn by the arm and the pressure when it is not restricted – in the final stages of deflation of the cuff.
This two-part process determines the diastolic and systolic numbers that make up the blood pressure score. Only one common wearable series uses (roughly) this blood pressure measurement method, the Huawei Watch D2.
It’s a very good miniaturization feat, but it’s not expected to be the method used by Apple.
Huawei Watch D2
How will the Apple Watch measure blood pressure?
Other watches that offer some form of blood pressure measurement rely on the photoplethysmography (PPG) device used to read heart rate throughout the day. This uses green and red/infrared LEDs to direct light onto the user’s wrist. And light sensors, acting like tiny cameras, record changes in reflected light as blood is pumped through the veins.
Using this method to determine the user’s heart rate is relatively simple, compared to blood pressure, which requires more source information than just heart rate.
Gurman suggests the Apple Watch Series 11 and the Watch Ultra 3 NO It’s actually used to output diastolic and systolic readings, like a $30 cuff solution from Amazon can, but instead it’ll let you know when it looks like your blood pressure is elevated. It’s a hypertension alarm that specializes in change, not straight numerical results.
A key question here is whether Apple’s solution will be more useful than a heart rate-based stress indicator that set off an alarm. After all, stress can cause a sharp increase in blood pressure.
Is an Apple Watch PPG sensor enough?
Several studies in just the last few years have addressed the use of PPG to analyze blood pressure, and a Nature paper from 2019 details the ways in which some promising applications of the concept fall either through limited accuracy or requiring multiple PPG recording sites.
This is where the long-rumored Apple ring concept gets more interesting. PPG readings on multiple pages could give the Apple Watch more substance as a blood pressure monitor. But in November 2024, Gurman claimed that Apple “has no plans to release” a smart ring.
A single-site PPG sensor is very limited when you stop to think about it. In the context of heartbeats, the lack of a well-defined context doesn’t really matter. The sensor doesn’t know what part of the wrist it’s looking at, where it is in relation to the wrist veins, or how the person’s skin color might affect the reflected light.
For heart rate that may not matter much, but it does for blood pressure.
However, a paper published in 2024 detailed a hardware-based system using a PPG sensor to record heart rate and blood pressure. And it found that it was able to detect hypertension with an accuracy of 92.42%, with the help of machine learning algorithms that estimate blood pressure from limited raw information.
A diagram from an Apple patent
Also in November 2024, the US patent office filed an Apple patent detailing the Apple Watch, which could use an inflatable strap that acts as a “sensing chamber” much like that of a traditional blood pressure cuff. blood. The difference here, however, is that the medium used to inflate the chamber is a liquid rather than air.
It’s an interesting and tricky-sounding technique to get into in an hour. But the vast majority of technology patents never end up as—and were never meant to be—actual products.
What is the receiver? It’s no wonder Apple took years to include blood pressure readings in the Watch family, even though Samsung brought it to the Galaxy Watch 4 in 2021. The main hope is that Apple’s slower approach will mean users don’t will need to regularly calibrate readings with a more conventional blood pressure cuff.
Apple is expected to introduce Apple Watch models with blood pressure readings – Series 11 and Ultra 3 – in September.
