A microfluidic erythrocyte sedimentation rate analyzer using rouleaux formation kinetics

Abstract

Red blood cell aggregation is an intrinsic property of red blood cells that form reversible stacked structures, also called rouleaux, under low shear rates. Erythrocyte sedimentation rate (ESR), commonly performed in clinics, is an indirect inflammation screener and a prognostic test for diseases. We have recently developed a microfluidic system for rapid measurement of ESR from 40 µl whole blood employing the aggregation dynamics. In this work, we propose the use of an aggregation inducer, dextran polyglucose, for the preparation of multiple blood samples with differing aggregation dynamics. Using these samples, we characterized the performance of the system with three aggregation indices and under varying experimental conditions. Additionally, using the same underlying principle, we improved the system for ESR measurement using both venipuncture and fingerprick whole blood samples depending on the user needs. The results demonstrate that the system performs equally well with both samples, which validates the compatibility of the system for both laboratory and point-of-care applications where venous and capillary blood are the primary samples, respectively. The detailed characterization presented in this study legitimates the feasibility of the system for ultrafast and facile measurement of ESR in clinics and diverse off-laboratory settings.