17 February 2010 PDMS surface modification in the application of waveguide claddings for evanescent field sensing
Author Affiliations +
Abstract
We fabricated SU-8 based slab waveguides on surface-modified poly(dimethyl siloxane) PDMS lower claddings for application in evanescent field sensing. In this application, higher sensitivity is obtained by generating stronger penetrating power above the waveguide into the analyte. This can be achieved by reducing the refractive index of the substrate. Compared with glass substrates that have a refractive index of 1.5, PDMS has a refractive index of 1.42 at 633 nm, thus serving as a better lower cladding material for high-sensitivity sensing with an evanescent field or as claddings in multilayer waveguide applications. In order to increase the adhesion of PDMS surfaces for successful SU-8 application we treated PDMS thin films in low-frequency (40 kHz) oxygen plasma for varied length of exposure time. The treatment process made PDMS hydrophilic and created nano-structures on the surfaces. The resultant surface topography with different exposure time was studied by an interferometric profiler on PDMS lower claddings and the later spin-coated SU-8 waveguides. Measurement results showed that longer plasma treatment on PDMS claddings significantly improved the uniformity and waviness of the waveguides. Light propagation tests performed with a prism coupler and an end-butt coupling setup proved that PDMS can be used as a proper material for SU-8 waveguides.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Meng Wang, Meng Wang, Sanna Uusitalo, Sanna Uusitalo, Risto Myllylä, Risto Myllylä, Leena Hakalahti, Leena Hakalahti, Markku Känsäkoski, Markku Känsäkoski, } "PDMS surface modification in the application of waveguide claddings for evanescent field sensing", Proc. SPIE 7593, Microfluidics, BioMEMS, and Medical Microsystems VIII, 759317 (17 February 2010); doi: 10.1117/12.841244; https://doi.org/10.1117/12.841244
PROCEEDINGS
9 PAGES


SHARE
Back to Top