Pulse Oximeters

Pulse oximeters are devices that measure blood oxygen saturation by beaming infrared light to a photodiode through a translucent part of the user's body - usually a finger or an earlobe.  The user's oxygenated hemoglobin absorbs some of the infrared light, and by measuring the light remaining when it is received by the photodiode, a pulse oximeter is able to determine a percentage of the blood oxygen saturation in a user's body.