Discussion:
oxygen meters
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RichD
2021-02-16 22:44:57 UTC
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Anybody know anything about the innards of those fingertip
O2 rate meters? sensor, theory of operation, silicon, etc.?

I recently had some medical treatment, they were checking it
3 times / day, and I'm curious -

I don't expect chemists to be experts on the electronics,
but maybe the chemistry -
--
Rich
Andy Burns
2021-02-17 00:02:43 UTC
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Post by RichD
Anybody know anything about the innards of those fingertip
O2 rate meters? sensor, theory of operation
Shine a red light and an infrared light through* a blood vessel onto an
opto sensor.

check the relative absorption of the two wavelengths in the blood, there
is a correlation between oxygen saturation and their absorption ratio.




[*] not reflected off the blood vessels like the phone versions.
dlzc
2021-02-17 13:47:55 UTC
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Post by Andy Burns
Post by RichD
Anybody know anything about the innards of those fingertip
O2 rate meters? sensor, theory of operation
Shine a red light and an infrared light through* a blood vessel onto an
opto sensor.
check the relative absorption of the two wavelengths in the blood, there
is a correlation between oxygen saturation and their absorption ratio.
And they can be fooled by CO in the blood too.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301832/
... just as we can produce acid in our muscles under stress, we can produce CO as well as part of an abnormal respiration...

David A. Smith
RonTheGuy
2021-04-02 06:22:41 UTC
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Post by Andy Burns
Shine a red light and an infrared light through* a blood vessel onto an
opto sensor.
check the relative absorption of the two wavelengths in the blood, there
is a correlation between oxygen saturation and their absorption ratio.
Why red?
TIA

Ron, the humblest guy in town.

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