These 16 sensors in smartwatches, fitness bands help in measuring heart rate, SpO2 and more

The color of blood is tested via the sensor to know the oxygen ranges found in it. As Fitbit explains, “Deoxygenated blood, which is returned for your lungs by means of your veins, is a rather darker purple colour than the totally oxygenated blood to your arteries. The sensors measure the relative mirrored image of purple and infrared gentle out of your blood by means of your wrist, and seeing the way it varies as your middle beats, the software estimates your SpO2 price.”