How does a pulse oximeter work? In the age of the pandemic, a highly sought-after medical device. The principle of its operation is based on the infrared radiation of LEDs. When they pass through blood vessels and soft tissues, oxygen is partially absorbed. Hemoglobin with oxygen and hemoglobin without oxygen absorb light waves of different lengths. The pulse oximeter works on the basis of this phenomenon - it analyzes the amount of light transmitted and shows it in the form of numbers.