Computational analysis of differently sized circulating tumor cells seclusion using cascaded deterministic lateral displacement array approach in microfluidics

In the cycle of uncontrolled tumor proliferation in cancer patients, cell fragments from the primitive tumor tissue disseminate throughout the body by blood flow stream or lymph, tagged as circulating tumor cells (CTCs), serve as an important biomarker for early cancer diagnosis. Deterministic Lateral Displacement (DLD) is one of the widely preferred passive particle segregation techniques operating on asymmetrical laminar flow distraction around the placed micropillars in an array pattern, based on the critical diameter of the device. In this simulation study, using COMSOL Multiphysics software, we propose a DLD device model with partitioned array of micropillars forming a cascaded pattern to isolate multiple CTCs from WBCs in an injected blood flow stream. The number of DLD sections used in this simulation study was reduced to 2 and isolation was achieved without introducing any sectional geometric array parameters variation for causing the splitting of cell trajectories. This design approach helped in improving the separation resolution of DLD devices while restricting the length of the device. Due to the dependency of critical diameter on the Reynolds number of incoming blood stream, after the fifth DLD row count, the modified critical diameter was shown to further bifurcate a closely sized CTC from the WBCs resulting in trapping of multiple CTCs with suitable isolation efficiency. From the simulation responses, it was observed that for three different sizes of CTC microbeads, the purity of extracted cells was on an average beyond 95%. The results of this computational study could help in future fabricated DLD designs for multiple bio-particle isolation.