piclist 1999\02\10\150843a >
Thread: heartbeats
face BY : Mark Willis email (remove spam text)

Stan Ockers wrote:
>                             Subject:                        Time:    1:04
> PM
>                             heartbeats
> 2/10/99
>                                                              Date:
> Does anyone know an easy way to convert heartbeats to pulses that a PIC
> could read?  I'm not interested in the amplitude but just the time between
> beats.  I would like to have a PIC log the times between beats to tell
> when they become irregular, especially when I'm asleep.

 The oxygen saturation and pulse rate sensors I've seen all TOO much of
when Robin's in hospital, have a red LED and a photosensor, perhaps an
IR pair as well, in something rather like a large plastic clothespin (I
know what they look like but didn't feel like disassembling them while
there <G>)

 You clamp it onto a finger and watch the light conductance waveform
for pulse rate, I know I've read before how they determine O2 saturation
but don't remember just now.  Basically, the blood pressure changes
change the light transmission through the skin <G>  I imagine you could
use this on a wristband or whatever as well, sort of a "back-scattering"
mode of the same thing.

 I thought that the chest tubes were mainly for breathing rates, (They
measure pressure changes from the tube's being stretched as your chest
expands/contracts) but it's entirely possible that an FFT or high pass
filtering or something on there - some devious wonderful trick - would
also disclose a pulse rate?  Anyone know?  Interesting things to learn
in this field for myself, I'm not much good on bio-sensors yet I'm
afraid <G>


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