Nonin created the first of these back in the '90s, so I pulled one of their spec sheets from 2016 (https://www.nonin.com/wp-content/uploads/2018/09/NoninConnec...) which explicitly mentions the pigmentation issue along with nail polish, poor circulation, and breathing issues. From that, this isn't exactly a new or unknown thing since commercial products have been working around this for some time. I wasn't able to find an industry standard for testing on these, so maybe the article should cite that as an opportunity to improve a product or add a new method?

> I wasn't able to find an industry standard for testing on these, so maybe the article should cite that as an opportunity to improve a product or add a new method?

It is a long article with many studies cited so I can't check all of those, IMO "the readings can be affected by skin tone" is not something that is sufficient for a medical device , what should a nurse or doctor do? There is no numeric value so what does that mean? is the device useless if you have dark sin or is it 2% wrong or as the article suggests the error is non linear and increases if you are suffering with low oxygen?

What I would do if I would sell this products is test with a few ranges of skin tones, and if needed have a switch on the device that you have to set for a certain level or if that is to expensive print instead of a number an interval and have the user trained to read that.