As the the title suggests, how is it that a little light they put on our finger when at the doctors/hospital/etc.. is able to tell us our blood oxygen levels?
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I haven’t seen an answer for a 5 year old yet, so ill try.
Oxygen binds to red blood cells. Red blood cells with oxygen absorb light differently than red blood cells without oxygen. You can measure light that passes through your finger and figure out how much oxygen is on your red blood cells.
Extra info. The reason its red light is because the light used is in the infrared spectrum, specifically, 940 and 660nm wave length. Well the 940nm is visible red light.
The reason for two wavelengths is because red cell with oxygen absorbs one wavelength and red cells without oxygen absorbs the other. This is how you get a percentage because its a ratio of oxygenated vs deoxygenated red cells.
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