Analytical Sciences

Abstract − Analytical Sciences, 28(1), 39 (2012).

Modification of the Glass Surface Property in PDMS-Glass Hybrid Microfluidic Devices
Shohei KANEDA,*1,*2,*3 Koichi ONO,*2,*4 Tatsuhiro FUKUBA,*5 Takahiko NOJIMA,*6 Takatoki YAMAMOTO,*7 and Teruo FUJII*1,*2,*3
*1 LIMMS-CNRS/IIS (UMI2820), Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153–8505, Japan
*2 CIRMM, Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
*3 JST CREST, Tokyo 102–0075, Japan
*4 Enplas Corporation, 2-30-1 Namiki, Kawaguchi, Saitama 332–0034, Japan
*5 Ocean Alliance, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277–8564, Japan
*6 College of Liberal Arts and Sciences, Kitasato University, 1-15-1 Kitasato, Minami, Sagamihara, Kanagawa 252–0373, Japan
*7 Department of Mechano-Aerospace Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152–8550, Japan
This paper presents a simple method to change the hydrophilic nature of the glass surface in a poly(dimethylsiloxane) (PDMS)-glass hybrid microfluidic device to hydrophobic by an extra-heating step during the fabrication process. Glass substrates bonded to a native or oxygen plasma-treated PDMS chip having microchambers (12.5 mm diameter, 110 μm height) were heated at 200°C for 3 h, and then the hydrophobicity of the glass surfaces on the substrate was evaluated by measuring the contact angle of water. By the extra-heating process, the glass surfaces became hydrophobic, and its contact angle was around 109°, which is nearly the same as native PDMS surfaces. To demonstrate the usefulness of this surface modification method, a PDMS-glass hybrid microfluidic device equipped with microcapillary vent structures for pneumatic manipulation of droplets was fabricated. The feasibility of the microcapillary vent structures on the device with the hydrophobic glass surfaces are confirmed in practical use through leakage tests of the vent structures and liquid handling for the electrophoretic separation of DNA molecules.