State the event, then size it: in early 2024, Apple disabled the blood-oxygen feature on Apple Watch models sold in the United States after losing an import dispute to medical-device maker Masimo over pulse-oximetry IP. That is not a footnote — it is the clearest example in consumer tech of a sensor patent dictating what a flagship product is allowed to do. The feature did not fail technically; it was switched off for legal reasons. The exposure was the entire blood-oxygen capability of a watch that sells in the tens of millions.
The reason a sensor patent could do that is worth understanding. Pulse oximetry — measuring blood-oxygen saturation by shining light through skin and reading how much is absorbed — sounds simple but is hard to do accurately on a wrist that moves, in ambient light, against varying skin. Masimo built decades of IP on doing it reliably, and that IP, not the idea of the measurement, is the asset. When a wearable claims a blood-oxygen reading, the question is always: whose method?
Masimo is still building. Its June 2026 publication US20260164483A1, "Patient-worn wireless physiological sensor with pairing functionality" (published June 11, 2026; inventor Ammar Al-Ali, Masimo's founder and the named inventor across much of its portfolio), reaches beyond the optical measurement into the device layer — a worn wireless sensor with pairing. Its classifications span A61B 5/14551 (the pulse-oximetry class) and A61B 5/1455 alongside wireless classes like H04W 76/14 and H04W 12. The filing is about the whole sensor node, not just the photodiode.
Note the discipline here: this is a published application, not a granted patent. That distinction is load-bearing. A publication stakes a claim to scope that the patent office has not yet confirmed; it signals intent and direction, but it does not yet carry the enforcement power that a grant does. In a category defined by litigation, the difference between "published" and "granted" is the difference between a flag planted and a fence built.
Why does a new sensor-and-pairing filing matter to the exposure story? Because the original fight was won on the sensor, and Masimo extending into the pairing-and-connectivity layer widens the surface where a future wearable could collide with its IP. The risk to a consumer-electronics company is not abstract "patent risk" — it is the concrete possibility that the next health feature it wants to ship reads on a claim owned by a dedicated medical-device firm that has already proven it will litigate and win.
The sober boundary: a publication is not a verdict, and not every wearable maker will infringe. But the structural lesson from the blood-oxygen episode holds — in wearable health sensing, the company that owns the measurement IP can constrain what the world's largest device makers are permitted to do, and Masimo's continued filing shows it intends to keep owning it. Put a number on that risk and it is the entire health-sensing roadmap of any watch that wants to measure your blood.