Home > News > News

Working principle of Pulse Oximeter

The oximeter uses non-invasive measurement infrared technology to measure fingers, toes, and ears. This is the most common place to measure the oxygen content in blood oxygen. The measurement object is more accurately called the blood oxygen saturation, which is SpO2. The test results are expressed in digital form, which mainly shows the ratio of total oxygen saturation under actual oxygen content, generally expressed as a percentage, the typical blood oxygen saturation of the human body is 90-100%, but the minimum can also be over To 60%. The human body's blood oxygen saturation depends on many factors, the most important of which is the poor blood supply of the patient's body, and the reading of HbO2 will decrease.

By sequentially driving a red light LED (660nm) and an infrared light LED (910nm), the blue line indicates the degree of induction curve of the receiving tube to reduced hemoglobin when the hemoglobin is without oxygen molecules, and the reduced hemoglobin pair can be seen from the graph The absorption of red light at 660nm is relatively strong, while the absorption length of infrared light at 910nm is relatively weak. The red line indicates the induction curve of oxyhemoglobin in the receiving tube when the hemoglobin is loaded with oxygen molecules. The absorption channel for 660nm red light is relatively weak, and the absorption for 910nm infrared light is relatively strong.

In blood oxygen measurement, reducing hemoglobin and aerobic hemoglobin, by detecting the difference between the two types of light absorption at different wavelengths, the measured data difference is the most basic data for measuring blood oxygen saturation. In the blood oxygen test, the two most common wavelengths of 660nm and 910nm actually have to achieve higher accuracy. In addition to the two wavelengths, they have to be increased, and even up to 8 wavelengths. The main reason is that the human hemoglobin is reduced In addition to hemoglobin and oxyhemoglobin, there are other hemoglobin. We often see carbon-oxygen hemoglobin. More wavelengths are beneficial to your accuracy.