Enhancing deterministic lateral displacement performance using asymmetric gap geometries under high Reynolds number flow.

The separation and detection of suspended particles are critical in a wide range of applications, including cell sorting and medical diagnostics. Microfluidic deterministic lateral displacement (DLD) is a promising technique due to its ability to continuously separate particles based primarily on size with high resolution. However, achieving high-resolution particle separation remains challenging, as it requires reducing gap sizes, which significantly increases hydraulic resistance and reduces device throughput. In this study, DLD devices with asymmetric gap configurations are proposed to overcome this limitation. By independently varying vertical and horizontal gap sizes, the proposed design enhances separation resolution while mitigating the increase in hydraulic resistance. A comprehensive numerical model is developed to investigate the effects of gap asymmetry, row shift fraction, and Reynolds number on hydraulic resistance and critical diameter. The results show that increasing the vertical gap significantly reduces hydraulic resistance, whereas decreasing the horizontal gap improves separation performance, enabling more efficient particle displacement. Furthermore, the influence of moderate to high Reynolds number flows is examined, revealing that although inertial effects slightly increase hydraulic resistance, their overall impact is minor compared to the benefits of asymmetric gap design. Based on the simulation data, a regression-based predictive equation is derived to estimate the critical diameter as a function of key design and flow parameters. The proposed approach has the potential to improve throughput and separation resolution while offering advantages in fabrication, and may provide useful guidance for the design of high-resolution DLD devices.