system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do the heart rate monitors that clip on to your finger also find oxygen levels?
gpt
One side of the clip has a light and the other has a sensor. When you clip it on your finger, it shines both red visible light and infrared light through you finger and it hits the detector. oxygenated blood and deoxygenated blood absorb different amounts of infrared and visible light, so by comparing the amounts that the sensor detects to the amount that was emitted, it can tell how much of your blood is oxygenated and how much isn't.