I read the history of using pulse metering for Oxygen levels, so looking at the wide field of pulse oximeters out there being used, I selected Phillips to see how they made theirs. It was done though a partnership with Masimo.
So Apple at best need to look at the
history and see if there is any wiggle room? Given the proliferation of this technology that looks like a lot is Masimo based, its pretty much an error on Apples part to not license it for a few bucks, and just stop the argument. It also predates anything that Apple could have ever developed recently. Below is from Wiki.
======
The first pulse oximetry was developed in 1972 by Japanese bioengineers Takuo Aoyagi and Michio Kishi at Japanese medical electronic equipment manufacturer Nihon Kohden, using the ratio of red to infrared light absorption of pulsating components at the measuring site. Nihon Kohden manufactured the first pulse oximeter, Ear Oximeter OLV-5100. Surgeon Susumu Nakajima and his associates first tested the device in patients, reporting it in 1975.[48] However, Nihon Kohden suspended the development of pulse oximetry and did not apply for a basic patent of pulse oximetry except in Japan, which facilitated further development and utilization of pulse oximetry later in U.S. In 1977, Minolta commercialized the first finger pulse oximeter OXIMET MET-1471. In the U.S., the first pulse oximetry was commercialized by Biox in 1980
By 1987, the standard of care for the administration of a general anesthetic in the U.S. included pulse oximetry.
in 1995, Masimo introduced Signal Extraction Technology (SET) that could measure accurately during patient motion and low perfusion by separating the arterial signal from the venous and other signals. Since then, pulse oximetry manufacturers have developed new algorithms to reduce some false alarms during motion,[53] such as extending averaging times or freezing values on the screen, but they do not claim to measure changing conditions during motion and low perfusion. So there are still important differences in performance of pulse oximeters during challenging conditions.[18] Also in 1995, Masimo introduced perfusion index, quantifying the amplitude of the peripheral plethysmograph waveform. Perfusion index has been shown to help clinicians predict illness severity and early adverse respiratory outcomes in neonates,[54][55][56] predict low superior vena cava flow in very low birth weight infants,[57] provide an early indicator of sympathectomy after epidural anesthesia,[58] and improve detection of critical congenital heart disease in newborns
