Grease the gears: how lubrication of syringe pumps impacts microfluidic flow precision

Leuthner, Moritz; Hayden, Oliver

doi:10.1039/d3lc00698k

Cited by 4 publications

(1 citation statement)

References 20 publications

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“…Once an optimal magnet position is found, no further hysteresis measurements are needed as long as the relative position of the magnet and GMR sensors are not changed. The syringe pump provides a pulsation-free sample flow [31]. The data acquisition board digitizes the signal from the lock-in amplifier and forwards it to a computer.…”

Section: Supplementary Materialsmentioning

confidence: 99%

Towards a Point-of-Care Test of CD4+ T Lymphocyte Concentrations for Immune Status Monitoring with Magnetic Flow Cytometry

Leuthner,

Reisbeck,

Helou

et al. 2024

Micromachines

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For the treatment of human immunodeficiency virus (HIV)-infected patients, the regular assessment of the immune status is indispensable. The quantification of CD4+ T lymphocytes in blood by gold standard optical flow cytometry is not point-of-care testing (POCT) compatible. This incompatibility is due to unavoidable pre-analytics, expensive and bulky optics with limited portability, and complex workflow integration. Here, we propose a non-optical, magnetic flow cytometry (MFC) workflow that offers effortless integration opportunities, including minimal user interaction, integrated sample preparation and up-concentration, and miniaturization. Furthermore, we demonstrate immunomagnetic CD4+ T lymphocyte labeling in whole blood with subsequent quantification using sheath-less MFC. Showing linearity over two log scales and being largely unimpaired by hematocrit, evidence is provided for POCT capabilities of HIV patients.

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Section: Supplementary Materialsmentioning

confidence: 99%

Towards a Point-of-Care Test of CD4+ T Lymphocyte Concentrations for Immune Status Monitoring with Magnetic Flow Cytometry

Leuthner,

Reisbeck,

Helou

et al. 2024

Micromachines

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Advancing magnetic flow cytometry to quantitative epitope analysis in high hematocrit conditions for point-of-care testing

Leuthner,

Helou,

Reisbeck

et al. 2025

Biosensors and Bioelectronics

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Quantitative Magnetic Flow Cytometry in High Hematocrit Conditions for Point-of-Care Testing

Leuthner,

Helou,

Reisbeck

et al. 2024

Preprint

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Quantitative cell analysis in liquid biopsies is essential for many clinical decisions, but it is primarily tied to centralized laboratories. However, access to these laboratories is limited in low-resource settings or for immobile patients, highlighting the urgent need for Point-of-Care (POC) testing infrastructure. Magnetic flow cytometers (MFC) offer a solution, albeit sample processing steps like cell lysis or washing crucially disrupt POC-capable MFC workflows. Here, we investigate conditions for immunomagnetic labeling and direct cell quantification in a streamlined workflow suitable for high hematocrit environments. Magnetic nanoparticles (MNP) are characterized by their size, magnetic moment, and potential to generate signal noise, favoring small (< 50 nm) MNPs. Theoretical models provide the framework for quantifying bound MNPs per cell, revealing labeling quality and giving insight into system requirements for reliable cell detection. Temporal labeling dynamics show suboptimal binding kinetics in whole blood (WB), leading to long incubation periods and only 50% recovery of optically determined concentrations. Besides showing quantitative MFC in WB with biomimetic microbeads, we finally quantify CD14+monocytes in WB with our streamlined workflow, achieving an intra-assay coefficient of variation (CV) of 0.11 and a CV across multiple donors of 0.10, demonstrating reliable POC flow cytometry close to regulatory standards.

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Grease the gears: how lubrication of syringe pumps impacts microfluidic flow precision

Abstract: Inadequately lubricated syringe pump parts can lead to 129% flow rate deviations in typical low-pressure (<500 mbar) lab-on-a-chip applications. With proper lubrication, five-fold smoother flow rates can be achieved for precise experiments (CV < 7%).

Cited by 4 publications

References 20 publications

Towards a Point-of-Care Test of CD4+ T Lymphocyte Concentrations for Immune Status Monitoring with Magnetic Flow Cytometry

Towards a Point-of-Care Test of CD4+ T Lymphocyte Concentrations for Immune Status Monitoring with Magnetic Flow Cytometry

Advancing magnetic flow cytometry to quantitative epitope analysis in high hematocrit conditions for point-of-care testing

Quantitative Magnetic Flow Cytometry in High Hematocrit Conditions for Point-of-Care Testing

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