A flow-rate independent cell counter using a fixed control volume between double electrical sensing zones

We present a novel cell counter using a fixed control volume and double electrical sensing zones at the inlet and outlet of the control volume. The present cell counter measures cell concentration based on the difference of the counted cell numbers from the double electrical sensing zones at inlet and outlet of the fixed control volume. In the experimental study, we use the RBC samples of three different concentrations and compare the results from the fabricated device with those from hemacytometer. Using the fabricated devices, we make two different measurements: 1) Cell concentration measurement using single electrical sensing at a fixed flow-rate of 10 /spl mu/l/min.; 2) Cell concentration measurement using double electrical sensing with the fixed control volume of 22.9/spl plusmn/0.98 /spl mu/l. Compared to hemacytometer, the single and double electrical sensing methods show the maximum errors of 20.3% and 16.1%, respectively, which are in the measurement error range of hemacytometer. We also observe that the present cell counter has an immunity for flow-rate change.