Validation and application of a microfluidic ektacytometer (RheoScan-D) in measuring erythrocyte deformability.

The deformability of erythrocytes primarily depends on the composition of the membrane and cytoplasm, which consist of hemoglobin and other constituents. Current techniques that measure erythrocyte deformability often require labor-intensive and time-consuming measurement processes. This article describes a newly developed microfluidic ektacytometer (RheoScan-D) that adopts advanced microfluidic rheometry and conventional laser-diffraction technique to determine the deformability of erythrocytes. Experiments are carried out to measure changes in deformability by treating erythrocytes in chemical agents with various concentrations (0, 0.3, 0.5 and 1.0 mM) of hydrogen peroxide, glutaraldehyde and diamide, and also by incubating erythrocytes at 49 degrees C for various time intervals (0, 5, 10 and 30 min), which affect the deformability through interaction with various constituents of erythrocytes. The measured Elongation Index (EI) of normal erythrocytes, a parameter directly related to erythrocyte deformability, at various shear stresses is in excellent agreement with those measured by a conventional ektacytometer (LORCA). The present technique is sensitive in detecting changes as produced by various chemical agents and high temperature. Alterations produced by hydrogen peroxide are the minimum and the maximums are produced by diamide treatment.