A lesser regarded point is the fact sensors can act as little batteries as a result of a galvanic influence due to a variance in concentration inside the sensor... ????: ???? ????? ????????? ?????? ?????? ??? ???? ???... ???? ???????: ??? ????? ?? ?????? ??? ?? ?????? ?? ?????? ????????... ?? ???????? ?????? ???? ???? ????? ????? ??????? ????? ???