IUBio

non contact heartrate aquisition

Richard Norman rsnorman at mw.mediaone.net
Wed Nov 18 16:58:22 EST 1998


Not too practical if the person moves even slightly!

The deviced described measures light absorption by
blood.  As the heart beats, the volume of blood in the
light path changes, changing the intensity of transmitted
light.  Movement of the finger within the device kills the
signal until the electronics can establish a new baseline.

The real question is whether you intend to monitor heartrate
on a cooperative subject or are trying to do it surreptitiously.

A cooperating subject would easily consent to wear a finger
or earlobe monitor which works using the light beam.  Also,
many exercise machines have metal electrodes that a subject
can grip which measure EKG.

Of course, these are all contact devices.



Kernsdoug wrote in message
<19981118132905.11921.00000713 at ng-fc2.aol.com>...
>hmm, Didier brings up an interesting idea -
>you could modulate a laser pointer and look
>at the return signal - with appropriate optics,
>such a thing might be able to give you a good
>guess at someone's heart rate from a great
>distance.
>
>  I wonder if anyone has already done this?
>
>Douglas Kerns
>electronic sensors and instrumentation
>d_kerns at alumni.caltech.edu.spam_bucket
>(remove the tail to get a real email address)
>>From: didier at Glue.umd.edu (Didier A. Depireux)
>>Date: Wed, Nov 18, 1998 12:02 EST
>>Message-id: <72uujd$d46$1 at hecate.umd.edu>
>>
>>no-spam at mjk.com wrote:
>>: How can I aquire a person's heartrate without a contact device?
>>
>>In high school, I built a little device... You put your finger in it,
there
>>was an LED shining bright red light on your finger from above, and the
>>photo-diode on the underside of your finger gave a signal that was
>>modulated by the heart pulsating through the finger (given the right
>>filters). Strictly speaking, you didn't have to touch anything, you
just had
>>to be close enough to the light source (in my days, you couldn't just
buy a
>>laser pointer...), and to the diode.
>>
>>These were the days!
>>
>> Didier
>>--
>>Didier A Depireux                              didier at isr.umd.edu
>>Neural Systems Lab                 http://www.isr.umd.edu/~didier
>>Institute for Systems Research          Phone: 301-405-6557 (off)
>>University of Maryland                                -6596 (lab)
>>College Park MD 20742 USA                     Fax: 1-301-314-9920
>
>





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