The method of water molecules counting during condensation process in the dew point detector

The paper presents a new method of water molecules counting during water condensation on the dew point detector surface. The method is based on the comparison of the theoretical calculations and the measurement results. The measurements were conducted in a special chamber able to keep the gas of demanded humidity in a constant volume and at a constant temperature. The dependence of the detector electrical parameters (the capacitance) as a function of the number of water molecules condensed on the detector surface was determined. The relatively low detector sensitivity at the beginning of the condensation process can be explained with help of the equivalent model of the capacitive humidity sensor based on lossy transmission line.