Detection of unlabeled particles in the low micrometer size range using light scattering and hydrodynamic 3D focusing in a microfluidic system

Guisheng Zhuang, Thomas G. Jensen, Jörg P. Kutter

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    In this paper, we describe a microfluidic device composed of integrated microoptical elements and a two‐layer microchannel structure for highly sensitive light scattering detection of micro/submicrometer‐sized particles. In the two‐layer microfluidic system, a sample flow stream is first constrained in the out‐of‐plane direction into a narrow sheet, and then focused in‐plane into a small core region, obtaining on‐chip three‐dimensional (3D) hydrodynamic focusing. All the microoptical elements, including waveguides, microlens, and fiber‐to‐waveguide couplers, and the in‐plane focusing channels are fabricated in one SU‐8 layer by standard photolithography. The channels for out‐of‐plane focusing are made in a polydimethylsiloxane (PDMS) layer by a single cast using a SU‐8 master. Numerical and experimental results indicate that the device can realize 3D hydrodynamic focusing reliably over a wide range of Reynolds numbers (0.5 <Re <20). Polystyrene particles of three sizes (2, 1, and 0.5 μm) were measured in the microfluidic device with integrated optics, demonstrating the feasibility of this approach to detect particles in the low micrometer size range by light scattering detection.
    Original languageEnglish
    JournalElectrophoresis
    Volume33
    Issue number12
    Pages (from-to)1715-1722
    ISSN0173-0835
    DOIs
    Publication statusPublished - 2012

    Keywords

    • Cytometry
    • Hydrodynamic focusing
    • Light scattering
    • Microfluidics
    • Particles

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