Flexible manipulation of microfluids using optically regulated adsorption/desorption of hydrophobic materials

Nagai, Hidenori; Irie, Takashi; Takahashi, Junko; Wakida, Shin‐ichi

doi:10.1016/j.bios.2006.08.037

Cited by 35 publications

(36 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With such applications in mind, some research groups have studied hydrophobic-hydrophilic micropatterning. 10,[19][20][21] In contrast to the previous works, we demonstrate that the wetting patterns can be erased actively in vacuum conditions or spontaneously in ambient conditions. This self-erasing property allows for example construction of channels for one application and later making new channels with different design on the same substrate.…”

contrasting

confidence: 89%

Self-erasing and rewritable wettability patterns on ZnO thin films

Kekkonen

Hakola

Kajava

et al. 2010

Applied Physics Letters

View full text Add to dashboard Cite

ZnO deposition on metal substrates: Relating fabrication, morphology, and wettability J. Appl. Phys. 113, 184905 (2013) Self-erasing patterns allow a substrate to be patterned multiple times or could store temporary information for secret communications, and are mostly based on photochromic molecules to change the color of the pattern. Herein we demonstrate self-erasing patterns of wettability on thin ZnO films made by atomic layer deposition. Hydrophilic patterns are written using UV light and decay spontaneously, i.e. become hydrophobic, or are erased aided by vacuum conditions or heat. We demonstrate that these patterns can be applied for channels to confine flow of water without physical walls.

show abstract

contrasting

confidence: 89%

Self-erasing and rewritable wettability patterns on ZnO thin films

Kekkonen

Hakola

Kajava

et al. 2010

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…23 Furthermore, a reversible flow switch also based on photocatalysis at the TiO 2 surface has been presented. 65 Titanium dioxide films may also be used to write metal nanoparticles on a microchannel wall after bonding, as shown by Castellana et al 52 A glass slide was coated with a 6 nm TiO 2 layer using chemical vapor deposition and bonded to a PDMS plate with 300 m wide microchannels. When irradiated with UV ͑365 nm͒ through a mask in the presence of silver nitrate solution ͑0.1 M, pH 5͒, the authors demonstrated patterning of silver metal at specific locations in the channels, Fig.…”

Section: B Photolithographymentioning

confidence: 99%

Surface patterning of bonded microfluidic channels

Priest

2010

Biomicrofluidics

View full text Add to dashboard Cite

Microfluidic channels in which multiple chemical and biological processes can be integrated into a single chip have provided a suitable platform for high throughput screening, chemical synthesis, detection, and alike. These microchips generally exhibit a homogeneous surface chemistry, which limits their functionality. Localized surface modification of microchannels can be challenging due to the nonplanar geometries involved. However, chip bonding remains the main hurdle, with many methods involving thermal or plasma treatment that, in most cases, neutralizes the desired chemical functionality. Postbonding modification of microchannels is subject to many limitations, some of which have been recently overcome. Novel techniques include solution-based modification using laminar or capillary flow, while conventional techniques such as photolithography remain popular. Nonetheless, new methods, including localized microplasma treatment, are emerging as effective postbonding alternatives. This Review focuses on postbonding methods for surface patterning of microchannels.

show abstract

“…Alternatively, non-mechanical methods for liquid valving such as surface-tension-guided microfluidics (STG) can be utilized to control liquid movement within flow channels. [2][3][4] In STG systems, a spatial difference in surface tension is utilized to generate a net force on the fluid thereby guiding the fluid towards the channel with higher surface tension. Several advantages of such systems include contact-less valving of fluid and the non-requisite of mechanically moving parts; these reduce biological/chemical compatibility issues between the fluid and microfluidic device interface.…”

Section: Introductionmentioning

confidence: 99%

“…6 As such, the enhanced reversible wetting of TiO 2 surfaces has been attempted through heating, 7 ultrasound, 8 mechanochemical agitation, 9 visible light irradiation 10 and the photocatalysis of hydrophobic molecules. 3,4 Recently, the TiO 2 hydrophilic-hydrophobic conversion was achieved by utilizing the surface adsorption of hydrophobic molecules (hydrophobic state) and the subsequent UV assisted photocatalysis of the initially adsorbed hydrophobic molecules (hydrophilic state) leached from a PDMS substrate. 3,4 However, the leaching of organic carbon content from PDMS raises some concerns with respect to the repeated use and rigidity of the PDMS molded channels.…”

Section: Introductionmentioning

confidence: 99%

“…Fluid motion control based on surface tension gradients can be achieved photochemically 2 and has previously been reported for Titanium dioxide (TiO 2 ) based microfluidic devices. 3,4 TiO 2 is a photo-sensitized semiconductor material that exhibits super-hydrophilicity upon irradiation with ultraviolet (UV) light of photon energy greater than its band gap (i.e. λ < 380nm).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reversible wetting of titanium dioxide films

et al. 2007

View full text Add to dashboard Cite

Titanium dioxide (TiO 2 ) films were rendered hydrophilic through ultraviolet (UV) light irradiation (254nm) and returned to their previous hydrophobic condition when exposed to a sealed pressurized nitrogen atmosphere. UV light irradiation on TiO 2 films resulted in super-hydrophilic surfaces with water contact angles of <5º. Alternatively, exposure of the films to an N 2 environment resulted in relatively hydrophobic surfaces with water contact angles of >40º. The switching of TiO 2 surface wettability could be repeated on the same surface with little hysteresis in water contact angle values. The mechanism behind the hydrophilic and hydrophobic reversal in TiO 2 surfaces is proposed to be due to UV light mediated photocatalysis and physio-adsorption of N 2 molecules respectively. The non-intrusive control of TiO 2 surface wettability could be an attractive alternative to other wettability-based microfluidic valving strategies like electrowetting and photochromic wetting variation. The above results are discussed in terms of the potential use of the films in wettability based valving and repeated wettability patterning of TiO 2 surfaces for open and sealed microfluidic systems.

show abstract

Flexible manipulation of microfluids using optically regulated adsorption/desorption of hydrophobic materials

Cited by 35 publications

References 22 publications

Self-erasing and rewritable wettability patterns on ZnO thin films

Self-erasing and rewritable wettability patterns on ZnO thin films

Surface patterning of bonded microfluidic channels

Reversible wetting of titanium dioxide films

Contact Info

Product

Resources

About