Efficient label-free CTC enrichment using novel elevated height chip chamber by vortex technology

Circulating tumor cells (CTCs) are essential evidence for monitoring tumor dynamics and efficient cancer therapy. Besides its clinical importance, it is a feasible method for liquid biopsy in oncological studies. Vortex is a label-free technique using inertial microfluidic technology to separate CTCs from blood with high throughput. A possible moderate separation efficiency arises due to the loss of particles from the vortex reservoir during particle-to-particle interactions. This study develops a novel three-dimensional reservoir geometry of the vortex with more efficient CTCs separation. In the proposed geometry, the height of the main channel is the same as the vortex chips and sets to 70 µm; however, the reservoir height increased to 100 µm. This design is called elevated height chip (EHC). The finite element simulation method is employed for optimizing reservoir height and working Reynolds number (Re). To verify the functionality of the EHC, the constant height chip design was also fabricated and showed a good correlation with the previously reported result. Both chips are tested with polystyrene beads (20, 15, and 8 µm) and MCF-7 cells. The results show 40% and 20% increase in efficiency for polystyrene beads and MCF-7 cells, respectively. Finally, it is demonstrated that 45% efficiency and 80% purity per cycle are achieved using the new proposed structure, and it is increased to 80% efficiency and 80% purity for over three cycles repetition.