pulse oximeter or breathing sensor

Has anyone interfaced a pulse oximeter or breathing sensor to a
Raspberry Pi? A Pi would be seem to be a natural for recording
either or both measurements.
Thanks.
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Robert Riches 
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Robert Riches
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On a sunny day (24 Jun 2018 04:33:44 GMT) it happened Robert Riches wrote in :
It would work, but the Pi needs quite a bit of power, and then needs battery backup if it is life critical.
I am using a Microchip PIC to write radiation levels and GPS location to SDcard, powered from a small lipo, uses hardly any power, runs on a charge all day long, and is smaller than a raspberry + batteries + GPS + radiation sensor. Not so easy to design and write the asm code:
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has been on 24/7, still uses same battery since May 2014 ;-) Some people do not believe you can recharge lipos that often. I use it as alarm clock (not logging).
But if your thing just sits on a table and is not power critical, then raspi is OK I think. And then you can use whatever language Pi supports...
I am using a Pi to log AIS ship data, position, airpressure, CO level, and lot of other things:
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also on 24/7 Website needs to be updated, thing looks totally different now... logs air traffic too..
In the end it all depends on you and what you can and want to do.
Reply to
Jan Panteltje
I bought a standard pulse oximeter, thinking it would be interesting to observe while I'm cycling. It wasn't - the oxygen level stays the same when exercising. I could make it drop by holding my breath while exercising, but that's not a useful observation, except to show it works. That's not to say it might not be useful in other scenarios such as sleep apnea or COPD.
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Andrew Gabriel 
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Andrew Gabriel
I have one that I'll wear if I take my glider high enough to need oxygen. UK regs say its advisable above 10,000 ft and mandatory above 12,000 ft, so wearing an oximeter is a worthwhile check on how well the oxygen system is working.
I've run it a few times but, as you say, it doesn't tell you much if you're in reasonable health under normal conditions near sea level.
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Martin    | martin at 
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Reply to
Martin Gregorie
I'm told they're useful devices to have for first-aiders as they're easier to use than trying to find a pulse.
Owain
Reply to
spuorgelgoog
They only work if you have a pulse, and it has to be regular. They can't work with someone who has an irregular heart beat, or no detectable peripheral pulse, because they have to be able to work out precise fractions of each pulse in order to derive the SpO2 level. Obviously, they can show an irregular pulse (if they can see one at all), but not work out the oxygen saturation in that case.
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Andrew Gabriel 
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Reply to
Andrew Gabriel
That's intriguing, for how does one calculate the O2 based on the fraction of time that the pulse is there?
Once had to do a PID control system for dissolved oxygen, but the glassware and probes were complex
Reply to
Gareth's Downstairs Computer
On Thu, 28 Jun 2018 19:08:47 +0100, Gareth's Downstairs Computer declaimed the following:
I don't think it's the fraction of time that the pulse is present so much as being able to sample two pulses in a row at the detected pulse rate -- in order to compare the detected light transmission at the two different wavelengths...
When I Googled the devices I seem to recall something that mentioned light transmission in deep (visible) red vs transmission of infra-red. Those measurements are done sequentially (the sensors can't quite differentiate the light source so it needs vr/pause/ir/pause... and slow detectors may require timing to catch the peak of the pulse for each).
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	Wulfraed                 Dennis Lee Bieber         AF6VN 
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Reply to
Dennis Lee Bieber
For a first aider that's probably more important than showing an oxygen level.
Owain
Reply to
spuorgelgoog
My googling a while back (when curiosity got the better of me) came up with the two different wavelength IR sources but I have no recollection of anything to do with time as far as the Sp02 was concerned. My recollection is of a reference/measurement type system.
Quick google, early hit,
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Bit "primary school" but seems to cover how a pulse oximeter works pretty well. Explains the problem(s) and then gives the solution(s). That link explains a reference/measurement system all be it with the "reference" at 950 nm moving about a bit but a lot less than the "measurement" at 650 nm.
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Cheers 
Dave.
Reply to
Dave Liquorice

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