Spiral tumor cell particle inertial focusing device based on secondary flow structure enhancement

The isolation of circulating tumor cells (CTCs) from blood is critical for clinical treatment, disease prediction, and numerous other applications. The use of rectangular cross section spirals for CTCs isolation has been reported extensively. But a high Reynolds numbers (Re) is required to achieve high target cell separation purity for the existing device. The present work proposes a novel microfluidic platform that combines a single-loop rectangular cross section spiral channel with an innovative array of convex structures, enabling continuous and highly effective separation of two types of CTCs [(human breast cancer cells (MCF-7) and A549 (human lung cancer cells)] from blood cells at lower Re. The array of convex structures enables to evaluate the focusing of target cells because an extra certain lift force is generated. The COMSOL Multiphysics 6.0 software and the finite element method were utilized to achieve the optimization of the geometries of array in detail. Additionally, the particle trajectory was studied under the distinct Re. The polymethyl methacrylate was utilized to construct the chip with an engraving machine. The polystyrene beads (24 μm), which imitate the MCF-7 cells, were used to verify the device performance. In the simulation, the optimized design with a single loop achieved 100% separation (24 , 15 , 10 , and 8 μm) at a Re of 68. Thus, this device holds promising potential as a sample pretreatment tool for clinical diagnosis.