Cancer Cell Separation Using Passive Mechanisms: a Review

The separation of micron-sized particles and their sorting is a critical issue in diagnosing cancer and biological analyses. For fast and accurate separation and sorting of circulating tumor cells (CTCs), various methods have been presented so far. CTCs which are responsible for cancer metastasis have the potential to provide significant prognostic and diagnostic values. In this paper, some procedures for the separation of CTCs are studied which are generally based on passive methods. These methods use the interaction between particles, flow field, and channel structure. In this study, various designs in connection with passive methods for separating and sorting CTCs are discussed, including filter/deformation, Pinched Flow Fractionation (PFF), Deterministic Lateral Displacement (DLD), inertia and Dean flow fractionation, tunable microfluidic systems, Hybrid microfluidics, and Carpet microfluidic chip technology. Overall, a list of challenges for the micro-fluidic-based cancer cell separation technologies needs to be dealt with to make them more applicable, useful, and ultimately more mature, from lab-oriented researches to real-world applications. It is suggested to perform numerical simulations by considering real shapes of rare cells. Besides, the impact of cell deformability, non-Newtonian impacts, and stretchable channels should be assessed in numerical examinations.