A microfluidic device, which is composed of a blood inlet, a cell lysis solution inlet, a bifurcation outlet containing six microchannels, and a white blood cell (WBC)-lysed solution outlet, is proposed in this study to separate WBCs from whole blood and lyse the WBCs in a continuous and near real-time fashion. The geometry of the microfluidic device is determined based on the bifurcation law and a cell crossover method. The microflow patterns of blood cells in the microfluidic channels are simulated by computational fluid dynamics. The simulation results agree with the experiment results by considering the reduction of blood viscosity in the microfluidic channels. The performance of the microfluidic device is evaluated by investigating the WBC recovery efficiency and the ratio of spectrophotometric absorbance of the blood sample at 260 to that at 280nm. The WBC recovery efficiency at the main channel outlet is 97.2%. The measured spectrophotometric absorbance ratio of 1.82 indicates that the separated WBCs are completely lysed, leaving only pure DNA in the WBC-lysed solution. The continuous cell separation and lysis is completed within only 0.5s. Therefore, it is concluded that the proposed microfluidic device is promising for separating WBCs from whole blood without any pretreatment and lysing the WBCs in a continuous and near real-time fashion. The proposed microfluidic device may be applicable to a lab-on-a-chip for blood analysis.
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