Continuous Separation and Mechanoporation of White Blood Cells from a Whole Blood Sample Through Micropillar Arrays

We propose a novel microfluidic technique for continuous separation and mechanoporation of human white blood cell (WBC) subpopulations (e.g., granulocyte, monocyte, lymphocytes) from small-volume whole blood samples (e.g., several tens of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{L}$</tex>) using a micropillar array. This technique leverages the unique flow dynamics within the array to generate forces that transiently disrupt cell membranes. Our method enables intracellular delivery of nanomaterials while addressing the limitations of conventional techniques, which often require preprocessing steps such as sample separation, exhibit cellular toxicity, and lack scalability. Using this approach, we achieved simultaneous separation and mechanoporation of WBCs, enabling efficient intracellular delivery of nanomaterials (e.g., FITC-dextran) with high cell viability (>95%). These promising results represent a significant advancement in nanomaterials delivery to difficult-to-inject cell types, paving the way for next-generation intracellular technologies.