High-Throughput Particle/Cell Separation Using Pressure Difference and Quasi Inertial Focusing in Curvilinear Parallel Microchannel

A microfluidic filtration device based on the configuration of two curved parallel lanes connected through a narrow bridge is investigated in this study. The bridge is oriented perpendicular to the main flow direction, making it possible to operate the device at high throughput without clogging. A pressure difference established between these parallel lanes produces fluid transfer across the bridge, while also enabling the migration of particles smaller than the bridge height and retaining and enriching bigger particles. In addition, Dean vortices, induced in the curved segment of the channel, can be used to enhance separation efficiency in this design. The device will be employed for separating and enriching circulating tumor cells (CTCs) from blood components such as red blood cells (RBCs) and white blood cells (WBCs). Separation efficiency of the filtration system is quantified by computational simulation, which has rarely been conducted until now. To do so, full 3D flow and particle simulations are conducted by using STAR-CCM+ software. The Saffman lift force, two-way coupling, and discrete element method (DEM) are considered in the particle simulation to obtain accurate results. This approach allows us to rationally optimize channel design in terms of separation efficiency, which can be quantified by simulating hundreds of particle trajectories within the separation device. Geometry and operation parameters, such as flow-rate, inlet length, and particle size, are investigated in terms of particle separation efficiency. Preliminary simulation results indicate the presence of unexpected quasi-inertial focusing observed in the curved segment of the flow path. Depending on the particle size, this focusing effect can reduce separation efficiency by limiting entry into the narrow bridge region, as well as offering an alternative explanation to conventional inertial focusing in curved channels. Preliminary experiments yield results comparable to the computational simulation. These findings reveal how the device design can be optimized for CTC enrichment by controlling the extent of inertial focusing experienced by each species to be separated. Future work will focus on applying these insights to demonstrate high-throughput isolation and enrichment of CTCs from whole blood