Dielectrophoretic field-fractionation of Rouleaux formed of human erythrocytes: A feasibility study

Resumen

Red blood cell (RBC) aggregation and specifically linear Rouleaux formation of human erythrocytes affects the rheology of microcirculation and has been widely studied in order to quantify flow abnormality in pathological conditions. Rouleaux forms through side-by-side adhesion of a considerable number of erythrocytes and may reach a roll length of 50 µm and more. This compares to the 2.2 µm in thickness of common RBC’s. Increased aggregation of RBC’s may be an important factor in the development of vascular diseases and microcirculation impairment. Dielectric properties of cell suspensions or of undiluted whole blood are strongly related i.e. to the geometrical structure of particles. Electrophoretic measurements or Rouleaux in various suspending media have the potential of size characterization and spatial separation of cell subpopulations. In the present paper we show, that the electrophoretic force on RBC aggregations of different size, exposed to an electric field of variable frequency, provides a means for a spatial separation and sorting of Rouleaux with different “stack number” of aggregated erythrocytes. In particular is the field-flow-fractionation technique a suitable tool, where the differential positioning of particles within a suspension flow velocity profile is established by the action of corresponding dielectrophoretic forces