Passive particle separation using an omega-shaped serpentine channel: Numerical study and surrogate model optimization with experimental validation

The presence of circulating tumor cells (CTCs) in the bloodstream of patients with cancer offers crucial insights into cancer progression and early diagnosis. In recent research, the detection and separation of CTCs using microfluidic devices have become as a primary point of interest, primarily because of their cost-effectiveness and facile implementation. This study introduces an omega-shaped microfluidic device designed for label-free and rapid enrichment of CTCs. Initial investigations employed numerical simulations to optimize the device geometry for enhanced separation quality. The numerical results indicated that a configuration featuring seven Omega channels at a velocity of 0.5 m/s achieved optimal separation, yielding a 100% recovery rate and 96.8% purity of CTCs. Subsequently, a device comprising seven Omega channels was constructed to evaluate the impact of varying flow velocities on CTC separation from blood cells. Experimental findings revealed that a flow velocity of 0.5 m/s facilitated optimal separation efficiency. Notably, the experimental results demonstrated an 88.8% recovery rate and 83.7% purity for CTCs, aligning with the numerical predictions. Furthermore, surrogate modeling was employed to explore the range of cancer cell types and optimize the aspect ratio parameter. The numerical results indicated an optimal aspect ratio of 0.2 within the designed microchannel, resulting in superior separation performance. In addition, it was observed that CTCs with a diameter greater than 20 μm achieved a 100% recovery rate with a purity of over 97%.