Multiplexed fluidic plunger mechanism for the measurement of red blood cell deformability

Red blood cell (RBC) deformability plays an important role in the pathology of various diseases, including malaria, hemoglobinopathies, and micronutrient deficiencies. Specifically, in malaria, the analysis of RBC deformability presents new approaches for detecting infections and for rapidly evaluating the response to drugs by patients. A key challenge, however, is that the infected RBCs represent only a small subpopulation of clinical blood specimens. Therefore effective detection of infection and analysis require methods that can measure a large number of individual RBCs. Traditional technologies for measuring RBC deformability either cannot evaluate single cells to identify diseased subpopulations or do not have sufficient measurement throughput to detect rare subpopulations. In additions, they require delicate experiments, expensive equipment, and skilled technicians. To address these issues, we developed a new microfluidic mechanism, known as the Multiplexed Fluidic Plunger (MFP), to measure RBC deformability using many microscale-tapered constrictions in parallel. The deformability of each RBC is determined by the threshold pressure required to squeeze the cell through a constriction. Our mechanism overcomes a key challenge where the pressure applied to each cell is dependent on the presence or absence of other cells and thereby produces in an inconsistent measurement result. We devised a mechanism to avoid this error and showed that a consistent measurement is obtained independent of constrictions occupancy. Furthermore, the sensitivity of the MFP device is comparable or superior to existing techniques since it can distinguish control and 0.0005% glutaraldehyde-treated RBCs (p