[hinkley]

I worked for a medical company in ‘97 that had an SPO2 meter they thought was pretty special. That would surely be out of patent now. Wikipedia has the first example as 1935, and Minolta making the first commercial model in 1977.

Most of them have the sensor and emitter on opposing sides of an earlobe, or a finger. So maybe that’s the unique part?

[kemayo]

The patent I've seen referenced is this one: https://patents.google.com/patent/US10912502B2/en

It seems to be a combination of describing an arrangement of sensors, strapping those sensors onto someone, and having the strapped-thing be a touchscreen device with wireless comms.

As a layperson it does sound like one of those patents which we like to make fun of -- the "X but with a computer" ones that're conceptually incredibly obvious. That said, I don't know if the sensor arrangement they describe is actually a novel thing that wasn't already out-of-patent elsewhere.