The Microfiltrometer (MicroFM): a new filtration device for the assessment of less deformable erythrocyte subpopulations.

The hardware of a new filtration device, the Microfiltrometer (MicroFM), is described. The different components of the device; impedance meter, power supply, measuring cell and its 5-micron Oligopore filter are described and it is shown how they are interrelated and interfaced to a computer for data acquisition. The properties of the filter and the general functioning principle of the device are also elucidated. For each run, the MicroFM generates elementary signals from individual passages of many hundreds of red blood cells (RBCs) through micropores of a given 5-micron Oligopore filter. Analysis of each elementary signal provides two complementary parameters, the transit time tau of the explored RBC and the change in electrical impedance deltaZ caused by the temporary flow of the considered RBC through a particular micropore of the filter. These two parameters can be utilized for reliable assessment of erythrocyte deformability on a cellular level.