A Consecutive Separation Strategy Using a 3D-Printed Microfluidic Chip to Achieve High-Purity White Blood Cells From...

Label-free and direct separation of white blood cells (WBCs) remains one of the major challenges in the field of efficient leukocyte separation. To address this challenge, we propose a WBC sorting strategy based on inertial microfluidics and 3D-printing technology, which employs a single inertial microfluidic chip to perform four consecutive high-throughput separation steps between red blood cells (RBCs) and WBCs. Specifically, the chip features a trapezoidal cross-section spiral channel to achieve size-dependent, stable spatial separation of cells along the inner and outer channels. After the conceptual design, the UV cured 3D printing technology is employed to fabricate the inertial chip and its fixture. Subsequently, mixed polystyrene microparticles are used as test objects to verify the sorting performance of the inertial chip, and the results indicate that the optimal separation flow rate is ∼1700  $\mu L/\min$ . This corresponds to a maximum WBC throughput of ∼1.12 × 10⁷ cells/h during a single-pass separation under the current 1:100 dilution condition, assuming a whole-blood WBC concentration of 1.1 × 10⁷ cells/mL. Ultimately, the diluted whole-blood samples are used to examine the four-cycle consecutive sorting strategy, and the results demonstrated that this strategy, proposed in this work, could directly obtain WBCs from blood samples with a recovery efficiency of ∼94.9% and a purity of ∼85.5%. Related experiments indicate that this strategy which is centered on the 3D-printed chip offers high reliability and sensitivity for label-free WBC sorting from blood cells. With the aid of state-of-art additive manufacturing technology, it is promising that our strategy could be widely applied on fields including cell analysis and disease diagnosis.