Computational Inertial Microfluidics: Optimal Design for Particle Separation

Abstract

Following the emergence of many blood transfusion-associated diseases, novel passive cell separation technologies, such as microfluidic devices, are increasingly designed and optimized to separate red blood cells (RBCs) and white blood cells (WBCs) from whole blood. These systems allow for the rapid diagnosis of diseases without relying on complicated and expensive hematology instruments such as flow microscopes, coagulation analyzers, and cytometers. The inertia effect and the impact of intrinsic hydrodynamic forces, the Dean drag force (FD), and the inertial lift force (FL) on the migration of particles within curved and complex confined channels have been explored theoretically, computationally, and experimentally. This study aimed to optimize the dimensions of a microfluidic channel for fast particle propagation and separation. Several spiral geometries with different cross-sections were tested using computational fluid dynamics (CFD) to separate two particle types representing RBCs and WBCs. The chosen three geometries consist of a single inlet, two outlets, and three spiral turns, each having a different cross-sectional height (120, 135, and 150 µm). Particle separation was successfully achieved in the 135 µm-height microchannel, while other microchannels demonstrated mixed particle types at the outlets.

Numerical Simulation of a Lab-on-Chip for Dielectrophoretic Separation of Circulating Tumor Cells

“…It is important to note that this model neglects the two-way cell–cell interaction and is fully dependent on the fluid–cell interaction. This is a common limitation in modeling particle trajectories [ 27 ].…”

“…Finally, some designs combine multiple separation techniques for separation. For instance, this can be performed by combining multiple geometries such as trapezoidal and rectangular cross-sections in a spiral microchannel [ 27 ] to make use of dean flow and the Zweifach–Fung effect for cell separation. The cross-section in such designs needs to be carefully optimized, including the outer and inner wall heights, the base width, and the slant angle, in addition to the number of turns of the spirals.…”

“…Each cell species will follow a particular trajectory based on the cell diameter, the viscosity of the medium and its flow rate. This leads to eventual separation at the end of the microchannel [27][28][29][30]. In contrast, pinched flow fractionation (PFF) [31,32] is Micromachines 2023, 14, 1769 2 of 18 a separation method that uses two flows: a sample and a pinch stream (buffer).…”