Dual-stage deterministic lateral displacement for pump-free and quantitative fractionation of whole blood

초록

Pump-free and quantitative fractionation of whole blood cells remains challenging in microfluidic systems due to the dependence on external pumping equipment and the difficulty of maintaining stable flow conditions for complex samples. In this study, we present a dual-stage deterministic lateral displacement (DLD) micro-/nanofluidic platform that enables label-free fractionation of whole blood cells under capillary-driven flow. The platform integrates two sequential DLD stages designed to separate white blood cells, red blood cells, and platelets based on size-dependent hydrodynamic behavior. A comparative analysis of DLD architectures reveals that an O-shaped pillar design yields superior separation selectivity and lower cell loss compared to an I-shaped design under identical operating conditions. Numerical simulations and experimental validations indicate that the symmetric curvature of O-shaped pillars promotes smoother streamline evolution and more predictable particle trajectories, enhancing displacement fidelity. To support continuous pumpless operation, an optimized capillary-driven pump was integrated, ensuring stable flow suitable for whole blood processing without external actuation. Separation performance was quantitatively assessed using an automated MATLAB-based image analysis workflow, which enabled reproducible and objective evaluation. High purities exceeding 89% were achieved for RBCs and PLTs with minimal cell loss. These results demonstrate effective whole-blood fractionation under capillary-driven flow and support its feasibility as a pump-free pre-analytical sample-preparation module.

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