Inertial Focusing in Triangular Cross-sectional Microchannel with Varying vertex angle and a/H.

Inertial microfluidics provides high-throughput, passive micro-particle manipulation methods which are widely used for various biomedical applications. We examined inertial focusing in isosceles triangular channels having various vertex angle (45°, 60°, 90°, 120°) and dimension with varying Reynolds number by changing flow rate. In particular, we investigated the top focusing positions shifting as a function of Re and a/H (a=particle diameter, H=hydraulic diameter). In case of 90° channels, the total number of focusing positions were changed from two to three as the Re is increased or a/H is decreased. Interestingly, three focusing positions become five in case of 120° triangular channel under high Re or low a/H conditions. The direction of shifting is differed whether vertex angle is acute or obtuse. Equilateral triangular channels do not show much changes due to 120° rotational symmetry. These results suggest various applications for particle manipulation and the understanding of roles of different lift forces.