Heart, ECG and pulse oximetry: GCSE revision

[@HAPPYPAL113]

Would you be able to give a lecture about, auditory brain response and cochlear microphonics physics. Thank you Bulent Mamikoglu MD

[@n3r0z3r0]

But the absorption of the infrared is also depending on the thickness of the let say finger, so how accurate this measurement may be?

[@valiza123]

Actually there are no pressure sensors inside, the pulse is extracted from the receiver usually the red light receiver / photodiode (AC Coupled). The oxygenation is calculated based on the absorbance or amount of reflected light, the light output has to be very close for both led's and the irradiance is compared for each led, the ratio of the absorbed red vs infrared gives the oxygenation. "Cool experiment" - used 3 powered red SMD led's placed around one unconnected red led (As receiver). Placed a oscilloscope on the unconnected led leads and saw the signal. Keep the finger steady because the signal's offset changes with the pressure you apply to the assembly. Put transparent tape over the led's to prevent you from touching the unpowered led's terminals.

[@n3r0z3r0]

valiza123 THANKS !!! I will try to test it by myself!