Altered blood rheology in multiwidth microchannels: hematocrit and tonicity variation

Abstract

We present a theoretical model for the characterization of the behavior of Newtonian and non-Newtonian fluids inside a microchannel with segments of different widths. This allows us to find the relation required to have collapsed viscosity curves for different fluids in just one experiment. Diverse experiments have been carried out with our setup. We consider different hematocrit concentration samples as well as samples of blood altered with different solutions in order to modify their tonicity. The data are acquired using microscale electronic detection of a fluid/air front advance. This will disclose different diseases that can be distinguished by the change in the normal rheological characteristics of blood or plasma. The results obtained demonstrate that using our setup and mathematical model, we can both distinguish blood with different concentrations of erythrocytes as well as discriminate when a same sample of blood is non-altered, altered with sodium chloride (NaCl) or de-ionized water (DIW), which emulates the abnormalities in the red blood cells of some pathologies. The results show that DIW causes blood to have more non-Newtonian behavior. On the other hand, NaCl causes the sample to become a hypertonic solution, causing the red blood cells to crenate, causing the blood to have a more Newtonian behavior.