Limitation of spiral microchannels for particle separation in heterogeneous mixtures: Impact of particles’ size and deformability

Spiral microchannels have shown promising results for separation applications. Hydrodynamic particle-particle interactions are a known factor strongly influencing focussing behaviours in inertial devices, with recent work highlighting how the performance of bidisperse mixtures is altered when compared with pure components, in square channels. This phenomenon has not been previously investigated in detail for spiral channels. Here, we demonstrate that, in spiral channels, both the proportion and deformability of larger particles (13 μm diameter) impact upon the recovery (up to 47% decrease) of small rigid particles (4 μm). The effect, observed at low concentrations (volume fraction