Integrative Magneto‐Microfluidic Separation of Immune Cells Facilitates Clinical Functional Assays

Abstract Accurately analyzing the functional activities of natural killer (NK) cells in clinical diagnosis remains challenging due to their coupling with other immune effectors. To address this, an integrated immune cell separator is required, which necessitates a streamlined sample preparation workflow including immunological cell isolation, removal of excess red blood cells (RBCs), and buffer exchange for downstream analysis. Here, a self‐powered integrated magneto‐microfluidic cell separation (SMS) chip is presented, which outputs high‐purity target immune cells by simply inputting whole blood. The SMS chip intensifies the magnetic field gradient using an iron sphere‐filled inlet reservoir for high‐performance immuno‐magnetic cell selection and separates target cells size‐selectively using a microfluidic lattice for RBC removal and buffer exchange. In addition, the chip incorporates self‐powered microfluidic pumping through a degassed polydimethylsiloxane chip, enabling the rapid isolation of NK cells at the place of blood collection within 40 min. This chip is used to isolate NK cells from whole blood samples of hepatocellular cancer patients and healthy volunteers and examined their functional activities to identify potential abnormalities in NK cell function. The SMS chip is simple to use, rapid to sort, and requires small blood volumes, thus facilitating the use of immune cell subtypes for cell‐based diagnosis.