Numerical Study of Effect of Flow Rates and Direction in Spiral Microchannel for Cell Separating

Circulating tumor cells (CTCs) are cancer cells that originate from a primary tumor cell and travels to other body parts through the bloodstream. These cells have valuable information about the advance of the patient and treatment response. Microfluidic separation techniques are used to separate them from blood, hoping that their data might be used to develop novel medicinal to treat more successfully. Nowadays, CTCs are isolated with external force (active separation) or without external power and rely on their shape, size, and other hydrodynamic parameters (passive separation). Passive technologies are often favored because of their simplicity, benefits of high throughput, and low cost; as well as this, there is no external force that shouldovercome the hydrodynamic drag force to obtain high performance; therefore, the flow rate is not limited. Inertia microfluidic is one of the passive technologies that isolates particles rely on their size. The existence of secondary flow in this microchannel helps differentiate the equilibrium position of particles with different sizes compared to the straight channel. Our previous article studied the cross-section as a useful parameter that can significantly change particles’ position. Here, we want to understand the effect of flow rate on separation efficiency and find golden flow rates. Furthermore, identify what will happen if the location of the input and outlet change, in other words, when flow passes from the larger radius toward the smaller onecompare to when flow passes from the smaller radius toward the larger one. In this article recovery rate for separation of CTC and Red blood cell (RBC) is studied in various flow rates. According to simulated data, when the inlet is in the inner radius, better separation with a recovery rate of۸۰% has been obtained by flow rate in the range of ۱۰۰۰ and ۱۵۰۰ μL/min. Moreover, it is exhibited that when the flow passes counterclockwise, separation has a lower recovery rate compare with clockwise separation. Furthermore, separating White blood cells (WBC) and CTC is more challenging than separating RBC and CTC as they have a noticeable difference in size.

Keywords:

passive separation , secondary flow , golden flow rate , trapezoidal cross section