navya14:
... since it is a digital sensor i am bit confused about how to test the sensitivity.
It seems to be an analogue photo interrupter (IR LED and photo diode) with "dirty water" in between.
Analogue output signal also goes to a threshold detector chip (LM358?).
The digital output is the output of that threshold detector chip.
Dirty/clean threshold can be set with the pot.
What A/D value do you get when you read the analogue pin in clean water and/or out of the water.
Leo..