Tunable velocity-based deterministic lateral displacement for efficient separation of particles in various size ranges

Deterministic lateral displacement (DLD) is a promising method showing great potential in achieving high-resolution separation of suspended particles based on their size, through the use of micropillars arranged in a periodic manner. In the traditional approach to DLD, the migration mode of a particle with a specific size is determined by the critical diameter (Dc), which is predetermined by the device's geometry. In contrast to conventional DLD chips that alter the direction of the pillar array to create an angle with the fluid streamlines, this paper proposes a novel approach by changing the direction of the streamlines. The proposed method enables the fabrication of a tunable DLD chip that is simple to produce and can generate a considerable Dc range by adjusting two control parameters. The first parameter is the ratio of velocity between the main outlet and minor outlets, with the main outlet located at the end of the microchannel and the minor outlets situated on the upper side. The second parameter is the flow rate ratio of two sheath inlets that controls particles' entrance position to the DLD chamber. By manipulating these parameters, Dc can be easily adjusted. This chip features completely horizontal rows of pillars that provide Dc values ranging from 1 to 25 μm.