how does a FINGER OXIMETER work?

Question

i already went to howstuffworks.com but i need more detail, i already know that it takes blood-oxygen saturation (SpO2) level and pulse-rate, what i need is how the SENSORS inside work. thanks!

Answer 1

It is a finger probe with a red light LED and an infra red "LED" and a sensor.

The LED's bounce the light off the finger(nail) and the sensor picks it up.

By calculating the different absorptions, the pulseOx is able to work out how much Oxyhaemoglobin is present and can give a SpO2 as a percentage.