Integrated blood cell counting device using a hydrophobic surface treatment

We fabricated an integrated blood cell counting system composed of planar blood preparation and blood cell counting devices. The planar blood preparation and counting devices were made of injection-molded polystyrene. 2 μL and 0.125 μL of whole blood were separated by hydrophobic passive valves and mixed with 50 μL of diluting fluid in the preparation device to accurately dilute the blood 25-fold and 400-fold, as primary and secondary dilution. We found that the hydrophobic fluoric resin surface treatments for the passive valves and the wall of the channels were effective for diluting whole blood. After the diluted blood was transferred into the blood counting devices, the number of blood cells was counted based on the change in electrode conductance at flow rate about 1 μL/s (50–500 cells/s). The coefficient of variation for the reproducibility of the blood cell counting was <2%, which is a desirable value for clinical use.