Investigation of fluid–structure interaction of micropillars in a three-dimensional microfluidic DLD array

Deterministic lateral displacement (DLD) is a microfluidic passive method for bioparticle separation and isolation, based on particle size and shape with high sample volume and low latency. Despite widespread application and research, experts report various fundamental, practical, and commercial challenges faced in the field of DLD represented in the literature. One of the fundamental challenges is the fluid’s flow behaviour and the fluid–structure interaction inside the DLD array. To address this problem, this paper investigates the modelling of a three-dimensional DLD array constructed by considering lateral displacements and wall boundaries. Nine different geometric shapes of the symmetrical pillars are reported in the literature opted for the study which are examined with different velocities to analyse how pillar shape impacts the flow patterns inside the DLD array. Also, an investigation of the two-way interaction between the fluid and the pillar structure is carried out. The response of the fluid due to the interaction with the pillar and the pillar response due to the interaction with the fluids is reported. Additionally, the realistic influence of the fluid flow and the surrounding pillars on the middle pillar in the array are examined in 3D simulations. The simulation was carried out using the finite element software COMSOL Multiphysics.