Microfluidic chip for blood cell separation and collection based on crossflow filtration

Whole blood is a mixture of various cells, such as red blood cell (RBC), white blood cell (WBC) and so on. Separation and collection of WBC and RBC, starting from a sample of whole blood, are the required steps for the subsequent clinica and basic research assays. We created two kinds of microfluidic chips based on the crossflow filtration principle which can be more effective than conventional types in the area of avoiding clogging or jamming. Pillar-type and weir-type filtration microchips were designed and fabricated by microelectromechanical system (MEMS) technology, in which parallel micropillar-array and parallel microweirs were used to separate cells via their different sizes. After separation, WBC and RBC were collected, respectively. Cell concentration and the length of separation channels were investigated and optimized. Under the optimal condition, more than 95% RBC can be removed from the initial whole blood, while 27.4% WBC can be obtained. Isolation efficiency of WBC by using the crossflow filtration microchip is approximately twice as high as that of the dead-end filtration microchip. Furthermore, plasma, WBC and RBC can be simultaneously separated and collected at different outlet ports with multilevel filtration barriers.