An Efficient Microscale Technique for Determining the Erythrocyte Sedimentation Rate

Abstract

The erythrocyte sedimentation rate (ESR) is a commonly used test to screen for inflammatory conditions such as infections, autoimmune diseases, and cancers. However, it is a bulk macroscale test that requires a relatively large blood sample and takes a long time to run. Moreover, it provides no information regarding cell sizes or interactions, which can be highly variable. To overcome these drawbacks, we developed a microfluidic microscopy-based protocol to dynamically track settling red blood cells (RBCs) to quantify velocity of cell settling, as a surrogate for the ESR. We imaged individual cells in a vertical microfluidic channel and applied a hybrid cell detection and tracking algorithm to compute settling velocities. We combined eigenvalue background subtraction and centroid detection together with the Kalman filter and Hungarian assignment solver algorithms to increase accuracy and computational speed. Our algorithm is designed to track settling RBCs/aggregates in high cellularity samples rather than single cells in suspension. Detection accuracy was 79.3%, which is comparable to state-of-the-art cell-tracking techniques. Compared with conventional ESR tests, our approach has the advantages of being automated, using microliter volumes of blood samples, and rapid turnaround.

Advances in Microfluidics for Single Red Blood Cell Analysis

“…The ESR is calculated based on the changes in the optical signals and results also show a very high correlation coefficient of about R 2 = 0.86 [218]. Furthermore, a vertical microfluidic system embedded with a cell-tracking system has been implemented for imaging to provide an edge over conventional analysis by reducing the sample volume and the analysis time [219]. RBCs also can form face-to-face branched or linear structures under static conditions or low-shear rates in the presence of appropriate macromolecules and are termed as 'rouleaux.'…”

“…Figure 12 shows an optofluidic point-of-care device for quantitative investigation of erythrocyte aggregation during coagulation with the schematics [221]. Another example for determining the erythrocyte sedimentation rate has enabled research of settling RBCs in terms of the diameter of cells and the population of cell/rouleau of different sizes [219]. Furthermore, the idea of combining the benefits of laser aggregometry, flow cytometry, and optical tweezers has been successfully implemented for the assessment of fibrinogen macromolecules interaction with RBC membranes [222].…”

Contributions of Red Blood Cell Sedimentation in a Driving Syringe to Blood Flow in Capillary Channels

“…In previous studies, a driving blood syringe was set in the vertical direction (i.e., upright or inverted). In addition, the hematocrit was set to relatively lower levels than the normal level of 45% (i.e., 0.1% [17], 20% [11], 25% [30], and 30% [21,31]). The hematocrit of the blood tended to increase over time when the blood was supplied from the bottom region of the syringe into the microfluidic device.…”

“…A previous method has been employed to detect differences in the ESR between control blood and periodontitis blood [5]. Seelamantula et al have suggested a hybrid imaging technique for computing the setting velocity of an individual RBC in a vertical microfluidic channel [17]. Elbuken et al have proposed a portable microfluidic opto-electro-mechanical system [18].…”

Sequential quantification of blood and diluent using red cell sedimentation-based separation and pressure-induced work in a microfluidic channel

“…[37][38][39][40] Blood plasma is then separated from blood aer a certain duration. Aer injecting small amounts of blood (75 mL, 41 40-200 mL 41 ) into a microuidic chamber, quantitative information of RBC sedimentation is obtained by measuring microscopic images, 42 optically transmitted light, 41,43 and blood conductivity 28 or electrochemical impedance. 44 In contrast, when blood samples are supplied to a microuidic device from a driving syringe pump, RBC sedimentation occurs continuously.…”