Oxygen blood meter?

I don’t know the right medical term for it but I mean the clip they put on your finger to measure how mych oxygen your blood holds.
Anybody got the knowledge of the inner workings of one of these?
If it is a siple/cheap setup i would like to build one to measure how my oxygen level changes when i hold my breath.

Ideas? Possible?


found me some info here: http://www.picotech.com/experiments/calculating_heart_rate/index.html
Just got to find me some time now to experiment with it.


I found this link.

It seems that you should use both a red LED and a Inrared Led if you should measure both the pulse and the blood-oxygen.

From what I read in a book, two LEDs are in the clip. One shines a beam
of infra-red. The ammount of light that passes out the other end of your
finger is measured. The other LED shines red light through. Once again,
the ammount of light that passes out the other end of your finger is
measured. The two values are then compared.
The medical term is a pulse oximeter. (I haven’t looked at the
link yet so I have no idea if I am repeating previously stated info. Sorry if
I am!)

Hmm… It looks like I repeated everything on there, word by word nearly!
Read the link first, then reply next time…

For now I’m satisfied with only the oxygen level but measuring the puls might be interresting too.
Good extra reading with the wikiarticle.

I was thinking of callibrating the measurement by just assuming that initially I’m always at say 99% en then see if it drops over time as I hold my breath. Now I can use the different wavelengths instead.

This is not a near future project of mine so don’t expect any breakthroughs for quite a while.

Thanks for your input!