Marzie Yaghubi - MSc student, Tarbiat Modares University;
Mohammad Zabetian Targhi - Assistant Professor of Mechanical Engineering, Tarbiat Modares University
Seyed Ali Tabatabaei - MSc graduated, Tarbiat Modares University;

CTC carries useful information about the tumor. By separating them from blood, their data can be used for understanding the advancing of the patient, treatment response, and developing novel medicinal to more successfully treat [1]. Microfluidic separation techniques are used for isolating CTC. Those can be classified as active or passive. Active one uses external forces like dielectrophoresis, magnetophoresis, and so on. In this method, the external force should overcome the hydrodynamic drag force to obtain high performance, so the flow rate is limited, but passive methods rely on hydrodynamic force. Passive technologies are often favored because of its simplicity, benefits of high throughput, and low cost.Among various passive microfluidic technologies, researchers have recently paid much attention to Inertial microfluidics. In this method, particle separation relies on its size. Particles whit different sizes stay on different equilibrium focusing Positions; the difference between the equilibrium focusing position is small within straight channels. However, in the spiral channels, secondary flow helps to get a more significant difference in the situation of the different particles [2]. In this article, we study the cross- section as a useful parameter that can change the position of particles significantly. There are a few researchers that compare differences between cross-sections. Our aim is to find a better cross-section between rectangular and trapezoidal for better separation.

passive separation, secondary flow, cross-section