Numerical design of a highly efficient microfluidic chip for blood plasma separation

Blood plasma separation may be one of the most frequent operations in daily laboratory analysis so that a highly efficient separation could save time, cost, and labor for laboratory operators. A numerical technique is demonstrated in this work to design a highly efficient microfluidic chip that can separate 64% plasma from blood with 100% purity. Simulations are carried out for the blood flow by a hybrid method of smoothed dissipative particle dynamics and immersed boundary method (SDPD-IBM). SDPD is used to model the motion of blood flow, while IBM is used to handle the interaction between cells and plasma. A single bifurcation, as the elementary component of the microfluidic chip, is first examined to find an optimal parameter group of flow rate and branch angle, which can generate a maximum separation efficiency on the premise of 100% purity. Then, the microfluidic chip is designed based on the optimal parameter group and compared with the existing experimental chip to analyze its performance. It is shown that the designed chip has a separation efficiency about 40% larger than the experimental one. Finally, the performance of the designed chip is analyzed by investigating the parameter dependence, and two critical parameters are studied, the cell hematocrit and inflow rate. The results provide an optimal hematocrit of 10.4% and an optimal inflow rate of 13.3 μl/h in order to obtain a high efficiency and 100% purity, which provides guidance for the level of diluting blood and the speed of injecting blood in experiments.