Spanwise dispersion optimizes the efficiency of dense microfluidic trap arrays

Microfluidic Trap Arrays (MTAs) have proved efficient tools for several applications requiring working at the single cell level like cancer understanding and treatment or immune synapse research. Unfortunately, it generally appears that many traps stay empty, even after a long time of injection which can drastically reduce the number of samples available for post-treatment. It has been shown that these unfilled traps were due to the symmetrical nature of the flow around the traps, with a break in symmetry improving capture efficiency. In this work, we use a numerical approach to show that it is possible to generate optimal geometries that significantly improve capture efficiency. This efficiency is associated with an increase in the lateral dispersion of the objects; we show that adding disorder to the layout of the traps is the most optimal solution and may stay very efficient independently of the trap array size. These numerical results are corroborated by experiments, validating our approach.