Tunable single-column deterministic lateral displacement device by adjustable crossflow

Conventional deterministic lateral displacement (DLD) devices are popular for continuous size-based separation of micro-particles at a high resolution through a tilted array of periodically placed micro-posts. However, the conventional DLD devices lack tunability of the critical size of particle sorting (D_C). In a conventional DLD device, the D_C is fixed by the device geometry. Further, many rows and columns of micro-posts are required in the device array to provide adequate spatial separation between large and small particles after lateral bumping of large particles, which leads to large device area and potentially small throughput/area. In this work, we present a novel tunable single-column DLD device where tunability was demonstrated by adjusting crossflow applied perpendicularly to the main flow direction. Our device consists of only 8 bumping obstacles with a device area of 0.83 mm × 0.24 mm = 0.2 mm² (without inlet/outlet ports). The ability to tune the critical size D_C from below 5 μm to above 10 μm in a single structure is demonstrated with a separation efficiency of ∼99.9% and the throughput/area is 45 μL min⁻¹ mm⁻². Further, at very high flow rates (Re > 10), the resolution degrades due to a three-dimensional fluid flow pattern.