Most of the newly developed pulse oximeters use a clip sensor probe. 

When in use, the probe can be clamped on the fingertip. 
The lower wall is a photosensitive receiving device, 

which converts the red and infrared light transmitted through the finger into electrical signals. 

When the oximeter is running, the time-sharing driving circuit makes the two light-emitting diodes emit light at a certain time interval and with a relatively low duty cycle.

 Calculate the whole blood absorption rate a660 and a940, and then combine the experimental calibration coefficients A and B into the corresponding formula, 

to calculate the value of blood oxygen saturation.

And this is a continuous and non-invasive blood oxygen measurement method, 

so it will not cause any pain and side effects to people's bodies.