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Deterministic lateral displacement (DLD) is a high-resolution passive microfluidic separation method for separating micron-scale particles according to their size. Optimizing these microsystems for larger throughputs and particle concentrations is of interest for industrial applications. This study evaluates the limitations of the functionality of the DLD separation principle under these specific conditions. For this reason, different particle volume fractions (up to 11%) and volumetric flow rates (corresponding to Reynolds numbers up to 50) were varied within the DLD microsystem and tested in different combinations. Resolved two-way coupled computational fluid dynamics/discrete element method (CFD-DEM) simulations including spherical particles were performed. The results show a general increase in the critical diameter with increasing volume fraction and decreasing separation efficiency. The largest tested Reynolds number (Re = 50) results in the highest separation efficiency, particularly at low volume fractions, and is only slightly less efficient than low Reynolds numbers as the volume fraction increases. The results indicate that by limiting the volume fraction to a maximum of 3.6%, the flow rate and the associated separation rate can be increased while maintaining a high separation efficiency. [ABSTRACT FROM AUTHOR]

Deterministic lateral displacement (DLD) microsystems are suitable for the size fractionation of particle suspensions in the size range of 0.1 to 10 µm. To be able to fractionate real particles beyond a laboratory scale, these systems have to be designed for higher throughputs. High flow resistances and increasing the clogging of the systems impose substantial challenges for industrial operation. Simulative parameter studies are suitable for improving the design of the systems; for example, the position and shape of the posts. A high-resolution, two-way coupled 6-DOF CFD-DEM approach was used to study the flow and particle behavior of different post shapes (circular and triangular) and post sizes at different Reynolds numbers. The results were compared with the classical first streamline width theory. It was shown that the streamline theory does not account for all effects responsible for the separation. Furthermore, a shift in the critical particle diameter to smaller values could be obtained when increasing the Reynolds number and also when using triangular posts with reduced post sizes compared to the post spacing. These findings can help to improve the efficiency of the systems as the post spacing could be extended, thus reducing the flow resistance and the probability of clogging. [ABSTRACT FROM AUTHOR]