Measurement Principles: A Pulse Oximeter is a non-invasive device for measuring the percentage of arterial blood (or hemoglobin) that is saturated with oxygen. This device can also measure heart rate. The principle of operation of a Pulse Oximeter is based on measuring the absorption of red and near-infrared light that passes through a patient's finger or ear lobe by utilizing light sensors. Oxy-hemoglobin absorbs infrared wavelength (800-940 nm) and deoxy-hemoglobin absorbs visible RED wavelength (600-700 nm).
LEDs are used as the light source and are sequentially pulsed at a fast rate. During a heartbeat, blood volume increases and the photodetector is used to calculate the absorption of oxy- and deoxy-hemoglobin. At the measuring site there are constant light absorbers that are always present like skin, tissue, venous blood, and the arterial blood. However, with each heartbeat the…
