Square-based spiral microchannel for the separation of circulating tumor cells using surrogate optimization based on the inertial method

Detecting circulating tumor cells (CTCs) in cancer patients’ blood and distinguishing them from blood cells are crucial for early cancer diagnosis and controlling therapy effectiveness. Scientists have increasingly turned to microfluidic devices to achieve this separation. Various methods exist for separating CTCs from blood cells, including the use of inertial forces, which is a well-established technique based on cell size. Although numerous computational and experimental investigations have been studied on circle-base spiral microchannel, the effect of the spiral's shape has not been extensively explored during separation. This study introduces a square-based spiral microchannel for label-free and rapid separation of CTCs. In addition, the effect of geometric parameters [i.e., the radius of fillet (R), number of fillets and aspect ratio (AR)] and practical parameters (i.e., Reynolds number for sample and sheath flow) have been investigated. Efficiency and purity are significant parameters that demonstrate the performance of the microchannel. The results showed that at Re = 6 for sample inlet and Re = 15 for sheath flow inlet with eleven fillets the efficiency was 100%, and the purity was over 90% of CTCs. Furthermore, surrogate optimization was employed to investigate the performance of the microchannel for different sizes of cancer cells (12–30 μm) and optimize the AR and R. The square cross section (AR = 1) and R = 150 μm yielded high efficiency and purity.