Pulse oximetry is a method of monitoring the heart rate and the level of oxygen in the bloodstream. Pulse oximetry is used mostly in hospitals but is gradually finding its way into home use and becoming popular with family doctors. It uses optical sensors and light-emitting diodes (LEDs) emitting light at different wavelengths through a finger tip where the transmitted light is detected using an optical sensor. Based on the principle of oxygenated hemoglobin having a higher absorption coefficient for infrared light than deoxygenated hemoglobin while deoxygenated hemoglobin absorbs more red light, by taking the ratio of absorbed red light to infrared light, the oxygen saturation level can be obtained.