In this study, a dielectrophoresis (DEP)-assisted inertial microfluidics methodology was introduced for the the isolation of circulating tumor cells (CTCs) from diluted blood samples. The methodology was based on the negative DEP, provided with the laterally allocated microelectrodes as well as the proper selection of the applied electric field frequency and voltage, to suppress the limited purity arising from the overlapped sizes of CTCs and white blood cells. Initially, the dynamics of 5 and 15 µm polystyrene microparticles within the DEP-assisted inertial microfluidic device were numerically and expimentally investigated. While the dynamics of the larger microparticles was governed by the inertial and DEP forces, those of the smaller microparticles were subject to the Dean drag force. In the absence of the DEP force, the larger microparticles migrate to two stable equilibrium positions corresponding to the upper and lower walls for the microchannel cross-section. In the presence of the DEP force, the equilibrium position corresponding to the lower wall is considerably displaced, while the equilibrium position corresponding to the top wall remains almost intact. Finally, it was found that the methodology outperformed the corresponding solely-inertial methodology in terms of purity for the isolation of CTCs from diluted blood samples. For instance, the purity of isolated MDA-MB-231 spiked in diluted blood samples, at a hematocrit of 1%, by the solely-inertial microfluidic device was 85.3%, while viable CTCs were captured using the DEP-assisted inertial microfluidic device with 94.1% purity at the total flow rate and applied voltage of, respectively, 650 µL min− 1 and 50 V.

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 (AR), number of turns, and pitch) and operational parameters (i.e., sample and sheath flow velocity) have 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.

In this study, a dielectrophoresis (DEP)-assisted inertial micro uidics methodology was introduced for the the isolation of circulating tumor cells (CTCs) from diluted blood samples. The methodology was based on the negative DEP, provided with the laterally allocated microelectrodes as well as the proper selection of the applied electric eld frequency and voltage, to suppress the limited purity arising from the overlapped sizes of CTCs and white blood cells. Initially, the dynamics of 5 and 15 µm polystyrene microparticles within the DEP-assisted inertial micro uidic device were numerically and expimentally investigated. While the dynamics of the larger microparticles was governed by the inertial and DEP forces, those of the smaller microparticles were subject to the Dean drag force. In the absence of the DEP force, the larger microparticles migrate to two stable equilibrium positions corresponding to the upper and lower walls for the microchannel cross-section. In the presence of the DEP force, the equilibrium position corresponding to the lower wall is considerably displaced, while the equilibrium position corresponding to the top wall remains almost intact. Finally, it was found that the methodology outperformed the corresponding solely-inertial methodology in terms of purity for the isolation of CTCs from diluted blood samples. For instance, the purity of isolated MDA-MB-231 spiked in diluted blood samples, at a hematocrit of 1%, by the solely-inertial micro uidic device was 85.3%, while viable CTCs were captured using the DEP-assisted inertial micro uidic device with 94.1% purity at the total ow rate and applied voltage of, respectively, 650 µL min − 1 and 50 V.