Numerical Simulation of Fluid Flow in Deterministic Lateral Displacement Devices

Deterministic lateral displacement (DLD) is a continuous, flow-based micro-particle separation method. DLD takes advantage of the laminar nature of the fluid flow in microchannels by directing the small particles along the main streamline of the fluid flow, while laterally displacing larger particles along the axis of the micropillar array. When optimally designed, this simple and energy-efficient method allows a high-resolution separation of particle mixtures carried along by the liquid at high velocity. In this paper, a numerical modeling of fluid flow inside of different DLD devices at different Re numbers is performed. A parametric study is conducted to assess the variation of theoretical critical particle size for various DLD devices. Parameters that affect flow velocity distribution, such as shift fraction and tilt angle are studied. Simulation results show that both micropillar shift fraction and the tilt angle significantly affect the velocity profile within the DLD device. A model is presented to describe the critical diameter for a wide range of pillar-diameter-to-gap-size ratios. The possibility of achieving greater throughput, while preserving flow characteristics and therefore particle separation efficiency, is demonstrated.