Re: optoelectronics questions
- You seem to be confused. A heart rate monitor usually monitors the
heart directly (i.e. an AED); LEDs and photodiodes are used in a
piece of medical equipment called a pulse oximeter which measures
oxygen saturation and pulse rate in the peripheral circulation. These
devices are already widely available and used by most paramedics. A
sensing probe clips onto the finger, toe or earlobe (in the case of
animals, the tongue is often used).
Use an IR emitter, the hemoglobin in the bloodstream is what absorbs
the light and its strongest absorbption is in the near IR. Use a
phototransistor for pickup; you can vary the base current on the
transistor to tweak the sensitivity. You can purchase finger probes
already made from most of the manufacturers of these units (go to
Google and use the keywords "pulse oximeter")
--- In email@example.com, "Fahad Salem" <ee_tool@h...>
>monitors. Is it
> Hello all,
> Can somebody please tell what type of emitting diode would be more
> effeciently used to detect bio-signals as used in heart rate
> better to use an infra-red or just a simple red LED for thispurpose.
>or just a
> Also, is it better to use a phototransistor to collect the signal
> photo-sensor (resistance) or what about a diode. This project ismeant to
> assist paramedics and make their job easier, any feedback iswelcomed.
> Thank you in advance
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