Characterization of Passive Microdevices for Dual-Use Selective Separation of White Blood Cells With Platelets and Plasma From Human Blood

Abstract White blood cells (WBCs) are essential in resisting and removing infection-causing foreign factors, and isolating them is vital in diverse applications. Microfluidic devices offer an edge in isolating white blood cells since passive microfluidic devices offer cost-effective sample processing crucial for diagnosis. A single device to separate various components of blood, such as plasma, WBC, and platelet, could yield significant advantages. To achieve this goal, here, we thoroughly evaluated several passive devices experimentally to determine their suitability for white blood cell separation from human blood. This study considered one blood plasma separation (BPS) device and two platelet separation devices. We further delve into the physical phenomena responsible for plasma and cell separation, exploring their similarities and differences using numerical tool. The behavior of cells in the flow path for various hematocrit values has also been uncovered over a wide range of flow rates. We found that red blood cells (RBCs) aggregation at the center of the channel helps in enhancing margination of WBCs. The shear rate has to be low to support the smooth separation of WBCs from other cells. The addition of a secondary flow boosts the separation as it broadens the streamlines of WBCs further away from the center of the channel. The aspect ratio, flow resistance ratio of the channels, and width of the cell-free layer play a significant role in WBC separation. This study is significant because it shows that a single microfluidic device can be employed for multiple purposes—obtaining WBC and platelet-rich plasma (PRP).