Blood cell fractionation using spiral inertial microfluidics

Abstract

White blood cells (WBCs) are integral in host immune system to maintain hemostasis and defense against foreign entities (e.g. virus) and diseases. Neutrophils are the most abundant WBCs in humans for innate immunity. Complete blood or WBCs/neutrophil counts are often measured in blood tests using hematoanalzyer but these results do not provide additional information such as cell functions which are indicative of inflammation. A major bottleneck is the high red blood cells (RBCs) background which hinder the isolation of WBCs/neutrophils for functional assays. Traditional methods require centrifugations or antibody binding which are time-consuming and may affect activate cells if not done properly. Hence there is a critical need to develop novel WBC and neutrophil isolation methods for point-of-care testing. In this thesis, we report a microfluidics technology termed as Dean Flow Fractionation (DFF) for direct and label-free isolation of WBCs and neutrophils from blood. A comparative study was first performed using 2 DFF microfluidic devices (of different channel heights and outlet configurations) to characterize sample to buffer flow rate ratios and blood dilution factor. Our results showed that DFF can achieve efficient WBCs (> 80%) and neutrophils (>85%) with ~99% depletion of RBCs using different channel designs. Taken together, the DFF is highly useful for label-free and rapid WBCs separation, and users can select the DFF chips to operate depending on the target cells of interests. We envision that DFF can be readily coupled with other microfluidic detection or functional assays in an integrated platform for point-of-care diagnostics.