So I am trying a Reflective Sensor to measure the change in inflation and deflation of vein under skin as the pulse moves through. The distance between the source and the skin is perhaps 1-2 mm. When this distance increases by about 1mm the ADC value of around 430 drops to 230.
My problem is that I am not able to detect any pulse. Understandably this system might not be as sensitive as it needs to be. Any way I can increase its sensitivity? Maybe sensitive enough to cause a change of 1000ADC values or at least 500ADC values for 1mm of distance change?
Since 230 is different from 430 I don't understand why you can't detect the difference. I would keep a running average and count a pulse when the input crosses the moving average in one direction or the other.
@johnwasser forget about the 230, it was just the adc value at say 3-4 mm distance from the IR source. Once at 230, it doesn't show any change while it should as the skin rises and falls (minutely) as the pulse passes in the vein.
@TomGeorge I don't need to measure the pulse, I need to see the degree of rise and fall of the tissue as the pulse passes underneath.
its a thin rubber membrane which is earlier at a distance of only about 1-2mm from IR source and about 1mm from the skin and then is brought in contact with the skin to uniform out any irregularities like hair etc.
Hi,
As you are looking at IR "reflectivity" to measure "relative" distance, have you looked at the IR reflectivity properties of the surface of the rubber membrane?
