Coupling Contraction-expansion Arrays with Spiral Microchannels to Enhance Microfluidic-Based Particle/Cell Separation

In the field of microfluidic inertial-based focusing of suspended particles, no research has been conducted to bring together two of the main directions of research, trapezoid spiral microchannels and contraction-expansion array (CEA)s. This paper addresses that gap by investigating two proposed CEAs (smooth and abrupt) inside a spiral channel compared to a uniform cross-section design at three different flow rates (i.e. 3, 6, and 9mL/min). The conservation equations of mass and momentum with a Lagrangian’-Eulerian (LE) approach are solved in OpenFOAM, using a four-way coupling between the phases. The results indicate that adding smooth transition CEAs to spiral microchannels, at a nominal flow rate 6mL/min, decreases the focusing duration (by about 29%) and the cell lysis probability (by about 52%) while keeping the separation efficiency high (nearly 100%). Overall, this study opens a promising new, integrated direction for passive microfluidic focusing of particles.