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Open AccessArticle

3D Hydrodynamic Focusing in Microscale Optofluidic Channels Formed with a Single Sacrificial Layer

1
Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602, USA
2
Electrical and Computer Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(4), 349; https://doi.org/10.3390/mi11040349
Received: 11 February 2020 / Revised: 25 March 2020 / Accepted: 26 March 2020 / Published: 27 March 2020
(This article belongs to the Special Issue Optofluidic Devices and Applications)
Optofluidic devices are capable of detecting single molecules, but greater sensitivity and specificity is desired through hydrodynamic focusing (HDF). Three-dimensional (3D) hydrodynamic focusing was implemented in 10-μm scale microchannel cross-sections made with a single sacrificial layer. HDF is achieved using buffer fluid to sheath the sample fluid, requiring four fluid ports to operate by pressure driven flow. A low-pressure chamber, or pit, formed by etching into a substrate, enables volumetric flow ratio-induced focusing at a low flow velocity. The single layer design simplifies surface micromachining and improves device yield by 1.56 times over previous work. The focusing design was integrated with optical waveguides and used in order to analyze fluorescent signals from beads in fluid flow. The implementation of the focusing scheme was found to narrow the distribution of bead velocity and fluorescent signal, giving rise to 33% more consistent signal. Reservoir effects were observed at low operational vacuum pressures and a balance between optofluidic signal variance and intensity was achieved. The implementation of the design in optofluidic sensors will enable higher detection sensitivity and sample specificity. View Full-Text
Keywords: 3D hydrodynamic focusing; optofluidic; lab-on-a-chip; biosensor; microscale channel; microfluidic; liquid-core waveguide; single layer; reservoir effect 3D hydrodynamic focusing; optofluidic; lab-on-a-chip; biosensor; microscale channel; microfluidic; liquid-core waveguide; single layer; reservoir effect
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MDPI and ACS Style

Hamilton, E.S.; Ganjalizadeh, V.; Wright, J.G.; Schmidt, H.; Hawkins, A.R. 3D Hydrodynamic Focusing in Microscale Optofluidic Channels Formed with a Single Sacrificial Layer. Micromachines 2020, 11, 349.

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