Browsing by Author "Wu, She-Ting"

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Fabrication of magnetic liquid marbles using superhydrophobic atmospheric pressure plasma jet-formed fluorinated silica nanocomposites
(2019-07-01)
Wu, She-Ting
;
Weng, Chih-Chiang
;
Li, Bor-Ran
;
Hsu, Chain-Shu
;
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In this study, the surface properties of iron microparticles were modified for the manipulation of liquid droplets using atmospheric pressure plasma jets. These modified hydrophobic iron microparticles were prepared by synthesizing fluorinated silica nanocomposites on the surfaces of iron microparticles under atmospheric pressure plasma. The compositions of the silica nanocomposites were controlled by the deposition of hexamethyldisiloxane and fluoroalkylsilane precursors. The fluorinated silica nanocomposites were then used with iron microparticles to prepare magnetic liquid marbles. The contact angles of the iron microparticles and the fluorinated silica nanoparticle coating on the glass surface were both 154 degrees, which indicated that the surfaces of these particles were superhydrophobic. Higher hexamethyldisiloxane precursor flow rates produced more silica nanocomposites and resulted in greater roughness and larger contact angles. Changes in surface roughness were characterized by atomic force microscopy. X-ray photoelectron spectroscopy showed that C-F bonds were present on the modified glass surface. The presented approach allows rapid and highly efficient modification of uneven surfaces and can therefore be employed to render hydrophilic, superhydrophobic, and oleophilic surfaces. Moreover, the described hydrophobic iron microparticles can be used for the controlled magnetic manipulation of water droplets and oil-water separation.
Rapid Prototyping of an Open-Surface Microfluidic Platform Using Wettability-Patterned Surfaces Prepared by an Atmospheric-Pressure Plasma Jet
(2019-10-08)
Wu, She-Ting
;
Huang, Chen-Yu
;
Weng, Chih-Chiang
;
Chang, Chia-Chih
;
Li, Bor-Ran
Open-surface microfluidics is promising in terms of enabling economical and rapid biochemical analysis for addressing challenges associated with medical diagnosis and food safety. To this end, we present a simple and economical approach to develop an open-surface microfluidic platform suitable for facile liquid transport and mixing. Customizable patterns with tailored wettability are deposited using a plasma-assisted deposition technique under atmospheric pressure. The flow of the dispensed liquid is driven by gravity, and the tilting angle of the device determines the extent of mixing. First, a hexamethyldisiloxane film was deposited to create hydrophobic patterns on glass, and then, hydrophilic acrylic acid was deposited by a patterned cardboard mask to construct a channel suitable for forming channels to transport aqueous liquids without the need of an external energy input; the liquid can be confined to designated pathways. Several designs including Y-junctions, serpentine-shaped patterns, splitting channels, and concentration gradient generation patterns are presented. The proposed method can spatially pattern a surface with a hydrophobic/hydrophilic area, which can function as a microfluidic channel, and the surface can be applied in microfluidic devices with other types of substrates.