A method of detecting a state of a lipid membrane in a cell of a nanopore based sequencing chip is disclosed. A lipid membrane is coupled with an integrating capacitor, wherein the lipid membrane is between a working electrode and a counter electrode. An alternating current (AC) voltage is applied to the counter electrode. A voltage across the integrating capacitor is periodically sampled by an analog-to-digital converter (ADC). A change in the sampled voltage across the integrating capacitor in response to an intermediate change in the AC voltage is determined. A state of the lipid membrane is determined based on the determined change in the sampled voltage across the integrating capacitor in response to the intermediate change in the AC voltage.