Publications by authors named "Kyungyong Choi"

Correction for 'Fully-automated and field-deployable blood leukocyte separation platform using multi-dimensional double spiral (MDDS) inertial microfluidics' by Hyungkook Jeon , , 2020, , 3612-3624, https://doi.org/10.1039/D0LC00675K.

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Separation of high-density suspension particles at high throughput is crucial for many chemical, biomedical, and environmental applications. In this study, elasto-inertial microfluidics is used to manipulate ultra-high-density cells to achieve stable equilibrium positions in microchannels, aided by the inherent viscoelasticity of high-density cell suspension. It is demonstrated that ultra-high-density Chinese hamster ovary cell suspension (>26 packed cell volume% (PCV%), >95 million cells mL ) can be focused at distinct lateral equilibrium positions under high-flow-rate conditions (up to 10 mL min ).

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A fully-automated and portable leukocyte separation platform was developed based on a new type of inertial microfluidic device, multi-dimensional double spiral (MDDS) device, as an alternative to centrifugation. By combining key innovations in inertial microfluidic device designs and check-valve-based recirculation processes, highly purified and concentrated WBCs (up to >99.99% RBC removal, ∼80% WBC recovery, >85% WBC purity, and ∼12-fold concentrated WBCs compared to the input sample) were achieved in less than 5 minutes, with high reliability and repeatability (coefficient of variation, CV < 5%).

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Acoustic fields have shown wide utility for micromanipulation, though their implementation in microfluidic devices often requires accurate alignment or highly precise channel dimensions, including in typical standing surface acoustic wave (SSAW) devices and resonant channels. In this work we investigate an approach that permits continuous microscale focusing based on diffractive acoustics, a phenomenon where a time-averaged spatially varying acoustic pressure landscape is produced by bounding a surface acoustic wave (SAW) transducer with a microchannel. By virtue of diffractive effects, this acoustic field is formed with the application of only a single travelling wave.

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Article Synopsis
  • Researchers tackled the issue of quickly identifying bacterial pathogens in infectious diseases by creating a new molecular method that uses ribosomal RNA for rapid detection without needing complicated amplification processes.
  • The developed assay demonstrated over 89% accuracy in identifying specific bacterial species and 100% accuracy at the family level from a diverse group of 117 bacterial isolates.
  • Initial tests using clinical samples like sputum and blood cultures effectively identified bacteria from five different phyla, showcasing its practical application in real-world situations.
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Airway secretions contain a large number of immune-related cells, e.g., neutrophils, macrophages, and lymphocytes, which can be used as a major resource to evaluate a variety of pulmonary diseases, both for research and clinical purposes.

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In blood samples from patients with viral infection, it is often important to separate viral particles from human cells, for example, to minimize background in performing viral whole genome sequencing. Here, we present a microfluidic device that uses spiral inertial microfluidics with continuous circulation to separate host cells from viral particles and free nucleic acid. We demonstrate that this device effectively reduces white blood cells, red blood cells, and platelets from both whole blood and plasma samples with excellent recovery of viral nucleic acid.

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Assessment of airway secretion cells, both for research and clinical purposes, is a highly desired goal in patients with acute and chronic pulmonary diseases. However, lack of proper cell isolation and enrichment techniques hinder downstream evaluation and characterization of cells found in airway secretions. Here, we demonstrate a novel enrichment method to capture immune-related cells from clinical airway secretions using closed-loop separation of spiral inertial microfluidics (C-sep).

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The present work aims to improve the sensitivity of an electrical biosensor by simply changing a surface property of the passivation layer, which covers the background region except for the sensing site for electrical isolation among adjacent interconnection lines. The hydrophobic passivation layer dramatically enhances the sensitivity of the biosensor when compared with a hydrophilic passivation layer. A revamped metal oxide semiconductor field-effect transistor (MOSFET), which has a designed underlap region between a gate and a drain, is used as the electrical biosensor.

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A new platform for lab-on-a-chip system is suggested that utilizes a biosensor array embedded in a digital microfluidic device. With field effect transistor (FET)-based biosensors embedded in the middle of droplet-driving electrodes, the proposed digital microfluidic device can electrically detect avian influenza antibody (anti-AI) in real time by tracing the drain current of the FET-based biosensor without a labeling process. Digitized transport of a target droplet enclosing anti-AI from an inlet to the embedded sensor is enabled by the actuation of electrowetting-on-dielectrics (EWOD).

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