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Proceedings Paper

Process development for waveguide chemical sensors with integrated polymeric sensitive layers
Author(s): Raghu Amberkar; Zhan Gao; Jongwon Park; David B. Henthorn; Chang-Soo Kim
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Paper Abstract

Due to the proper optical property and flexibility in the process development, an epoxy-based, high-aspect ratio photoresist SU-8 is now attracting attention in optical sensing applications. Manipulation of the surface properties of SU-8 waveguides is critical to attach functional films such as chemically-sensitive layers. We describe a new integration process to immobilize fluorescence molecules on SU-8 waveguide surface for application to intensity-based optical chemical sensors. We use two polymers for this application. Spin-on, hydrophobic, photopatternable silicone is a convenient material to contain fluorophore molecules and to pattern a photolithographically defined thin layer on the surface of SU-8. We use fumed silica powders as an additive to uniformly disperse the fluorophores in the silicone precursor. In general, additional processes are not critically required to promote the adhesion between the SU-8 and silicone. The other material is polyethylene glycol diacrylate (PEGDA). Recently we demonstrated a novel photografting method to modify the surface of SU-8 using a surface bound initiator to control its wettability. The activated surface is then coated with a monomer precursor solution. Polymerization follows when the sample is exposed to UV irradiation, resulting in a grafted PEGDA layer incorporating fluorophores within the hydrogel matrix. Since this method is based the UV-based photografting reaction, it is possible to grow off photolithographically defined hydrogel patterns on the waveguide structures. The resulting films will be viable integrated components in optical bioanalytical sensors. This is a promising technique for integrated chemical sensors both for planar type waveguide and vertical type waveguide chemical sensors.

Paper Details

Date Published: 13 February 2008
PDF: 8 pages
Proc. SPIE 6886, Microfluidics, BioMEMS, and Medical Microsystems VI, 68860U (13 February 2008); doi: 10.1117/12.765237
Show Author Affiliations
Raghu Amberkar, Missouri Univ. of Science & Technology (United States)
Zhan Gao, Missouri Univ. of Science & Technology (United States)
Jongwon Park, Missouri Univ. of Science & Technology (United States)
David B. Henthorn, Missouri Univ. of Science & Technology (United States)
Chang-Soo Kim, Missouri Univ. of Science & Technology (United States)

Published in SPIE Proceedings Vol. 6886:
Microfluidics, BioMEMS, and Medical Microsystems VI
Wanjun Wang; Claude Vauchier, Editor(s)

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