i have to acquire a wrist pulse signal using micriphone, and for that i have used microphone and instrumentation amplifier INA110, i have grounded the negative terminal of microphone and the second terminal is given to 2 pin of INA110 to provide differential signals to amplifier. in order to provide potential to 1 pin i have connected a 1 Mohm potentiometer. But when i am observing results on ossciloscope the signal gets saturated and it is showing constant dc voltage. what should i do eliminate this problem.