Man, if you ever want to cut in line at the ER, just say “chest pains.” I did that Thursday afternoon, and in about three minutes the ER crew had stripped off my shirt and had me on a gurney with about a dozen electrodes planted on my torso, oxygen in place, an IV insert, a shot of morphine and various other control measures instituted. Nitro tabs under the tongue - Yum, yum.
One of the many instruments they used was a device that they clipped on my index finger. When asked, the nurses told me that it measured the oxygen content of my blood. It appeared to use UV light.
How does this device work?