Impact of Cell Deformability on Inertial Focusing in Spiral and Straight Microfluidic Channels

The increasing demand for rapid and high-throughput cell separation, crucial for medical diagnostics and cell purification, has triggered the advancement of microfluidic platforms. Inertial microfluidics, characterized by its label-free, physics-based approach, has emerged as a promising technique. It leverages microscale physics to achieve efficient cell separation, primarily based on particle size. However, the deformable nature of cells complicates their arrangement within microchannels, introducing a novel force, the deformability-induced lift force. This study investigates the potential of separating cells by their deformability within an inertial flow setting. It specifically explores both straight and spiral microfluidic channels, known for their relevance in inertial particle migration. By altering cell deformability through chemical and physical treatments, without inducing any size variation, the cell focusing behavior was examined at channel outlets, emphasizing the impact of operational parameters like flow rate and channel geometry. The primary aim is to demonstrate that cells of identical size but varying deformability focus at different positions at the channel outlet, which will provide infromation for a label-free approach for deformability-based sample purification. The results show that deformable cells concentrate closer to the channel centerline than their rigid counterparts, with spiral channels exhibiting enhanced performance due to the Dean drag force. Furthermore, cell behavior significantly deviates from that of rigid particles, emphasizing the limitations of using particles as cell surrogates for microchannel predictions. In conclusion, this study provides data that support the understanding of how hydrodynamic forces interact in the inertial migration of cells within microfluidic devices, taking into consideration the variability of cellular properties. These observations have practical applications in cell separation technologies and medical diagnostics, particularly in the detection of diseases associated with changes in cell mechanical properties.