PDMS surface modification in the application of waveguide claddings for evanescent field sensing

Wang Meng, Sanna Uusitalo, R. Myllylä, Leena Hakalahti, Markku Känsäkoski

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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.
Original languageEnglish
Title of host publicationMicrofluidics, BioMEMS, and Medical Microsystems VIII
Place of PublicationUSA
PublisherInternational Society for Optics and Photonics SPIE
DOIs
Publication statusPublished - 2010
MoE publication typeNot Eligible
EventMicrofluidics, BioMEMS, and Medical Microsystems VIII, SPIE MOEMS-MEMS, 2010 - San Francisco, United States
Duration: 25 Jan 201027 Jan 2010

Publication series

NameProceedings of SPIE
PublisherSPIE
Number7593

Conference

ConferenceMicrofluidics, BioMEMS, and Medical Microsystems VIII, SPIE MOEMS-MEMS, 2010
Abbreviated titleSPIE MOEMS-MEMS, 2010
CountryUnited States
CitySan Francisco
Period25/01/1027/01/10

Fingerprint

waveguides
refractivity
sensitivity
siloxanes
oxygen plasma
couplers
prisms
topography
slabs
adhesion
low frequencies
propagation
glass
thin films

Cite this

Meng, W., Uusitalo, S., Myllylä, R., Hakalahti, L., & Känsäkoski, M. (2010). PDMS surface modification in the application of waveguide claddings for evanescent field sensing. In Microfluidics, BioMEMS, and Medical Microsystems VIII [759317] USA: International Society for Optics and Photonics SPIE. Proceedings of SPIE, No. 7593 https://doi.org/10.1117/12.841244
Meng, Wang ; Uusitalo, Sanna ; Myllylä, R. ; Hakalahti, Leena ; Känsäkoski, Markku. / PDMS surface modification in the application of waveguide claddings for evanescent field sensing. Microfluidics, BioMEMS, and Medical Microsystems VIII. USA : International Society for Optics and Photonics SPIE, 2010. (Proceedings of SPIE; No. 7593).
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title = "PDMS surface modification in the application of waveguide claddings for evanescent field sensing",
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.",
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Meng, W, Uusitalo, S, Myllylä, R, Hakalahti, L & Känsäkoski, M 2010, PDMS surface modification in the application of waveguide claddings for evanescent field sensing. in Microfluidics, BioMEMS, and Medical Microsystems VIII., 759317, International Society for Optics and Photonics SPIE, USA, Proceedings of SPIE, no. 7593, Microfluidics, BioMEMS, and Medical Microsystems VIII, SPIE MOEMS-MEMS, 2010, San Francisco, United States, 25/01/10. https://doi.org/10.1117/12.841244

PDMS surface modification in the application of waveguide claddings for evanescent field sensing. / Meng, Wang; Uusitalo, Sanna; Myllylä, R.; Hakalahti, Leena; Känsäkoski, Markku.

Microfluidics, BioMEMS, and Medical Microsystems VIII. USA : International Society for Optics and Photonics SPIE, 2010. 759317 (Proceedings of SPIE; No. 7593).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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T1 - PDMS surface modification in the application of waveguide claddings for evanescent field sensing

AU - Meng, Wang

AU - Uusitalo, Sanna

AU - Myllylä, R.

AU - Hakalahti, Leena

AU - Känsäkoski, Markku

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

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M3 - Conference article in proceedings

T3 - Proceedings of SPIE

BT - Microfluidics, BioMEMS, and Medical Microsystems VIII

PB - International Society for Optics and Photonics SPIE

CY - USA

ER -

Meng W, Uusitalo S, Myllylä R, Hakalahti L, Känsäkoski M. PDMS surface modification in the application of waveguide claddings for evanescent field sensing. In Microfluidics, BioMEMS, and Medical Microsystems VIII. USA: International Society for Optics and Photonics SPIE. 2010. 759317. (Proceedings of SPIE; No. 7593). https://doi.org/10.1117/12.841244