The question is related to impedance cell counting, determining cell`s size etc. This method is working like this: "A small portion of the diluted fluid in each bath is allowed to flow past a small aperture. An electrical current is produced in each aperture by two electrodes, one on the inside and the other on the outside of the aperture. The saline solution is responsible for conducting current between the electrodes. The cells move through the aperture one at a time. When a cell enters the aperture, it displaces a volume of electrolyte equal to its size. The cell acts as an electrical resistor, and impedes the flow of current. This produces a voltage pulse, the magnitude of which is proportional to the size of the cell. Instrument electronics are adjusted to discriminate voltage pulses produced by different cells." - Surgery Encyclopedia So my question is: How it is guaranteed that only one cell will pass through this aperture? Maybe two little cells can pass through it and make a resistance as if one big have passed?