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Fabrication of Patterned Superhydrophobic/Hydrophilic Substrates by Laser Micromachining for Small Volume Deposition and Droplet-based Fluorescence Detection Kyle John Bachus, Lili Mats, Heeyoon W Choi, Graham T.T. Gibson, and Richard David Oleschuk ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b16363 • Publication Date (Web): 07 Feb 2017 Downloaded from http://pubs.acs.org on February 12, 2017
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ACS Applied Materials & Interfaces
Fabrication of Patterned Superhydrophobic/Hydrophilic Substrates by Laser Micromachining for Small Volume Deposition and Droplet-based Fluorescence K.J. Bachus1, L. Mats1, H.W. Choi1, G.T.T. Gibson2, and R.D. Oleschuk1* 1
Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6, Canada
[email protected] 2
CMC Microsystems, Innovation Park, Kingston, ON, K7L 0E9, Canada
Keywords: superhydrophobic materials, superhydrophobic-hydrophilic, patterned surfaces, laser micromachining, droplet microfluidics, 3D-printed microfluidics, fluorescence detection
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ACS Applied Materials & Interfaces
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Abstract: The deposition of nanoliter and sub-nanoliter volumes is important in chemical and biochemical droplet-based microfluidic systems. There are several techniques that have been established for the deposition/generation of small volumes including the use of surfaces with patterned differences in wettability. Many such methods require complex and time-consuming lithographic techniques. Here, we present a facile method for the fabrication of superhydrophobic surfaces with patterned hydrophilic regions by laser micromachining. A comprehensive study of fabrication parameters (laser machining speed, laser power, and patch size) on the material, patch wettability, and droplet volume is presented. Patch sizes as small as 100 µm diameter and as large as 1500 µm diameter were investigated and volumes as low as 400 pL were observed. As an example application of such patterned materials and the deposition of small volumes, halide salts were pre-concentrated on the hydrophilic patches and their fluorescence quenching constants were rapidly calculated using a 3D-printed device coupled to a fluorescence spectrometer.
1. Introduction Superhydrophobic surfaces are those which have high water contact angles (>150°) and low sliding/roll-off angles (
