| Summary: | Neutrophils are the most abundant type of white blood cells in humans and their cellular biophysical properties are associated with immune dysfunctions in diseases. While neutrophils can be isolated from whole blood using density gradient centrifugation, fluorescence activated cell sorting (FACS) and magnetic activated cell sorting (MACS), these conventional methods are laborious and time consuming, and are thus not suitable for clinical testing. The gold standard for single cell analysis is flow cytometry which requires expensive antibodies staining and may affect neutrophil native state. To address these challenges, we herein report an integrated microfluidic platform that combines viscoelastic cell sorting and impedance cytometry in a “blood-in, answer-out” microdevice to directly profile neutrophils in a low cost and label-free (no antibodies) manner. In this thesis, we first characterized the separation of microbeads (5, 7 and 10 μm) and neutrophils using viscoelastic fluids of varying concentration, followed by the biophysical profiling of cells via impedance measurement. Our results showed efficient separation of neutrophils, achieving approximately 3.5 fold enrichment from whole blood. Successful detection and measurement of neutrophil cell properties were also demonstrated with distinct impedance-based differences in deformability and membrane opacity between 10 μm beads and neutrophils. Taken together, these results indicate the potential of the developed blood testing chip for automated and quantitative single neutrophils analysis towards repaid inflammatory risk stratification and clinical diagnostics.
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