Design of microfluidic-based microarrays for rapid, efficient single-cell isolation

One of the most important potential applications of stem cells is the generation of cells and tissues for cell-based therapies. To understand the impact of a stem cell initial phenotype on subsequent fate decisions studies at the single cell level are necessary. In this work, the design, prototyping and characterization of a microfluidic device for single cell isolation based on the principle of hydrodynamic trapping is proposed. The optimization of the trap design was carried out and an accurate estimation of the stress acting on the cell membrane was obtained through the numerical modeling of a deformable cell flowing in microchannels. Microfluidic experiments on PDMS prototypes were then performed. Fluid dynamics simulations of the trapping process showed a flow partitioning between the main channel and the trap channel favorable to the trapping events and levels of stress acting on the cell surface less than 1Pa were found for the working conditions adopted. Experiments to assess the efficiency of single cell trapping showed perfect arraying of single cells or particles. Trap selectivity was also verified. Finally, the working principle of the trapping/shunting device was demonstrated with an experiment on one trap unit. However, the devices must be optimized for each cell type and designed according to the trap size to cell size ratio. This innovative research is among the first to couple numerical simulations and experiments to accurately investigate cell behavior in flow in a complex geometry in order to optimize the design of effective microdevices for cell isolation, to ensure cell viability and ultimately to improve such highthroughput microdevices, which still represents one of the most significant challenges in the field of stem cells.