A microfluidic device for partial cell separation and deformability assessment

Abstract

Blood flow in microcirculation shows several interesting phenomena that can be used to develop microfluidic devices for blood separation and analysis in continuous flow. In this study we present a novel continuous microfluidic device for partial extraction of red blood cells (RBCs) and subsequent measurement of RBC deformability. For this purpose, we use polydimethylsiloxane (PDMS) microchannels having different constrictions (25%, 50% and 75%) to investigate their effect on the cell-free layer (CFL) thickness and separation efficiency. By using a combination of image analysis techniques we are able to automatically measure the CFL width before and after an artificial constriction. The results suggest that the CFL width increases with enhancement of the constriction and contributes to partial cell separation. The subsequent measurements of RBCs deformation index reveal that the degree of deformation depends on the constriction geometries and hematocrit after the cell separation module. The proposed microfluidic device can be easily transformed into a simple, inexpensive and convenient clinical tool able to perform both RBC separation and deformability analysis in one single device. This would eliminate the need for external sample handling and thus reducing associated labor costs and potential human errors.

Microbubble moving in blood flow in microchannels: effect on the cell-free layer and cell local concentration

“…In microfluidic systems and in capillary vessels, the RBCs have a size that is a significant fraction of the size of the channel. Effects due to the discrete size of the cells, such as the formation of a plasma layer (Leble et al 2011, Garcia et al 2012, Pinho et al 2013, plasma skimming (Faivre et al 2006), the Zweifach-Fung effect (Svanes and Zweifach 1968, Fung 1973, Doyeux et al 2011, the Fahraeus effect (Fåhraeus 1929) and the Fahraeus-Lindqvist effect (Fåhraeus and Lindqvist 1931) are relevant. A plasma layer or cell-free layer (CFL) is usually formed near the wall of small vessels due to the migration of red blood cells to the center of the microchannel.…”

In vitro blood flow and cell-free layer in hyperbolic microchannels: Visualizations and measurements

“…As a result, it is possible to obtain the CFL thickness. The procedure to track individual RBCs is presented and discussed in more detail elsewhere 7,19 .…”

“…The advantage of the microfluidic systems to test a large number of cells using a small volume of blood has promoted a large amount of research in the field of biomicrofluidics 1,2,6,7 . Furthermore, lab-on-a-chip technology combines portability, integration and automation in a single chip, and is thus a promising platform for point-of-care devices, which may be particularly useful for detection and diagnosis of circulatory disorders.…”

Visualization and Measurement of the Cell-Free Layer (CFL) in a Microchannel Network

“…The cell-free layer is a well-known physiological phenomenon that was studied both in in vivo [3][4][5][6][7] and in vitro [8][9][10][11][12][13] studies. This phenomenon results on the RBCs axial migration toward the center of a simple and straight microchannel.…”