Numerical investigation of centrifugal passive cell separation in three types of serpentine microchannels and comparison with fixed platform

Cell separation plays a crucial role in diagnosing and improving a wide range of diseases, such as cancer, which is a severe reason for the death of people in the current decades. Circulating tumor cells (CTCs) inside the blood can be separated from the other whole blood cells to detect early cancer. Inertial methods are more superficial and cost less than the current CTC separation methods. These methods also have great potential in high-throughput separation in lab-on-a-chip (LOC) and lab-on-a-disk (LOD) devices because of secondary flow generation, especially in serpentine-shaped microchannels. The present study considers a continuous process for separating CTCs from the blood sample. This process is utilized in LOD devices, and this platform is also compared with the LOC platform. Moreover, two common types of different serpentine-shaped channels (simple and curved) and a new Omega channel are compared. It should be noted that a direct numerical simulation (DNS) method is used for calculating lift force in the serpentine-shaped channels. The effect of fluid velocity on WBC and CTC separation efficiency in the three mentioned different geometries are investigated in both fixed and rotational platforms, then the best results for each of them are presented. Finally, the best results belonged to the simple serpentine between the three investigated channels, with a separation percentage of 100. Moreover, in comparing the two mentioned platforms, LOD showed a more efficient application in cell separation. In addition, the Omega channel is investigated as a novel serpentine geometry. According to the results, it can be used for particle focusing applications thanks to its 100 percent efficiency at 0.5 m/s in both LOD and LOC platforms.