Comparison of logarithmic, elliptic, and conical helical spiral for isolation of circulating tumor cells based on inertial method

Cancer is one of the most significant causes of death in the world. It has been shown that the role of circulating tumor cells (CTCs) in the early detection of cancer is crucial. Since the number of these cancerous cells in blood is very rare, the inertial microfluidic devices are one of the best candidates for the isolation of CTCs because they result in a high throughput process. Consequently, they can process a large volume of blood in a short time. Despite extensive computational and experimental studies on inertial microfluidic platforms, the impact of the curvature has not been thoroughly investigated during separation. In this paper, the feasibility of isolation of CTCs for logarithmic, elliptical, and conical helical spirals has been examined using a computational approach. In addition, the effect of geometrical parameters (i.e., the radius of curvature, aspect ratio, number of turns, and pitch) and operational parameters (i.e., sample and sheath flow velocity) has been studied. While the results showed that all three geometries could isolate CTCs with 100% purity and efficiency, the elliptical spiral was nominated as an optimal geometry since the inertial migration of particles can be completed faster as a result of forming alternating Dean drag forces in this geometry.