From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: searching for a pulse rate sensor
Date: Sat, 18 Jan 2003 05:12:59 GMT
NNTP-Posting-Date: Fri, 17 Jan 2003 21:12:59 PST
Chuck Simmons wrote:
> Barry Lennox wrote:
> > On 17 Jan 2003 18:18:39 -0800, firstname.lastname@example.org (Joe Blo) wrote:
> > >I am designing a project where I need a pulse rate sensor.
> > >I could scavange one from an off the shelf pulse-rate meter, but I
> > >would rather get one with a data sheet that helps me to determine how
> > >I can interface it to a microcontroller to read the pulse rate of a
> > >human.
> > I took a close took at the inside of one a while back, it had a
> > plastic housing that went over your finger, with an IR LED on one side
> > and a photodiode on the other. The theory is that the blood pulsing
> > through your finger modulates the amount of IR reaching the
> > photodiode.
> The ones I experienced during a recent hospital stay combined blood
> oxygen measurement with pulse measurement. These used a visible red LED.
> Unfortunately, I was not allowed to dissect one in my then copious spare
> time to see how it worked.
I guess I don't have to dissect one after all.
Assuming I'm sort of normal, you can expect blood oxygen saturation to
be 90% or above so IR might be marginally better than visible red.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com