title: Flexible manipulation of microfluids using optically regulated adsorption/desorption of hydrophobic materials.
abstract: To realize highly integrated micro total analysis systems (microTAS), a simply controlled miniaturized valve should be utilized on microfluidic device. In this paper, we describe the application of photo-induced super-hydrophilicity of titanium dioxide (TiO2) to microfluidic manipulation. In addition, we found a new phenomenon for reversibly converting the surface wettability using a polydimethylsiloxane (PDMS) matrix and the photocatalytic properties of TiO2. While PDMS polymer was irradiated with UV, it was confirmed that hydrophobic material was released from the polymer to air. Several prepolymers were identified as the hydrophobic material with a gas chromatograph and mass spectrometer (GC/MS). Here, we successfully demonstrated the flexible manipulation of microfluid in a branched microchannel using the reversible wettability as micro opto-switching valve (MOS/V). The simultaneous control of MOS/Vs was also demonstrated on a 256-MOS/V integrated disk. The MOS/V promises to be one of the most effective flow switching valves for advanced applications in highly integrated micro/nano fluidics.
authors.affiliation: Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan. hide.nagai@aist.go.jp
authors.forename: Hidenori
authors.initials: H
authors.lastname: Nagai
authors.forename: Takashi
authors.initials: T
authors.lastname: Irie
authors.forename: Junko
authors.initials: J
authors.lastname: Takahashi
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Wakida
mesh_terms: D000327:Adsorption; D004129:Dimethylpolysiloxanes; D057927:Hydrophobic and Hydrophilic Interactions; D044085:Microfluidics; D012828:Silicones; D014025:Titanium
chemical_list: D004129:Dimethylpolysiloxanes; D012828:Silicones; C009495:titanium dioxide; C013830:baysilon; D014025:Titanium