3D hydrodynamic focusing in microscale channels formed with two photoresist layers
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3D hydrodynamic focusing was implemented with channel cross-section dimensions smaller than 10 μm. Microchannels were formed using sacrificial etching of two photoresist layers on a silicon wafer. The photoresist forms a plus-shaped prismatic focusing fluid junction which was coated with plasma-enhanced chemical-vapor-deposited oxide. Buffer fluid carried to the focusing junction envelopes an intersecting sample fluid, resulting in 3D focusing of the sample stream. The design requires four fluid ports and operates across a wide range of fluid velocities through pressure-driven flow. The focusing design was integrated with optical waveguides to interrogate fluorescing particles and confirm 3D focusing. Particle diffusion away from a focused stream was characterized.
Keywords3D hydrodynamic focusing Optofluidic Microscale channel Liquid-core waveguide
This work was supported by funding from the National Institutes of Health under Grant 1R01AI116989, and the National Science Foundation under Grant CBET-1703058.
The study conception and design were performed by ESH, JGW, and ARH. Modeling and fabrication were performed by ESH. Data collection and analysis were performed by VG, WGP, and HS. The first draft of the manuscript was written by ESH and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
ARH and HS have a financial interest in Fluxus Inc. which commercializes optofluidic technology.
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