Masimo only refined pulse oximetry in the 90s, as pulse oximetry was invented in the 1970s (prior oximeters did not resemble the devices seen today). Everything after that has been tweaks/improvements to the base method, but I wouldn't call them the inventors of the technology.
The only IP that companies can own now are specific methods/improvements, not the base idea of measuring SpO2 with light. All Apple has to do is avoid the specific improvements that Masimo owns and they are fine.
Yes. I recall the brand new pulse oximeters (I don't recall the manufacturer) that appeared in the ORs at UCLA Medical Center right around when I started my anesthesiology residency in 1977. They were SUPER expensive when they first came out, so much so that our department bought 3 of them, which were used only for the most critical cases. I remember the chief resident sometimes had to decide who got one when 2 residents/attendings each said their patient was more unstable/critical and thus needed it more.
These were NOT small devices like the inexpensive fingertip versions you can buy now over the counter; rather, they were big boxlike machines, perhaps 2 feet x 1.5 feet x 8 inches high. They were SO heavy (I'd estimate 25 pounds) they were attached to a stainless steel rolling cart.
The only IP that companies can own now are specific methods/improvements, not the base idea of measuring SpO2 with light. All Apple has to do is avoid the specific improvements that Masimo owns and they are fine.
https://en.wikipedia.org/wiki/Pulse_oximetry#History