Fabrication and characterization of silicon nitride directional coupler interferometer for sensing aptamer hybridization

K. Okubo, K. Uchiyamada, M. Yokokawa, K. Asakawa, H. Suzuki

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

Abstract

We used silicon nitride (Si3N4) directional coupler (DC) interferometers to fabricate evanescent field biosensors for detection of aptamer hybridization. The DC detects temporal changes in refractive index (RI) as changes in the relative intensities of near-fields. Numerical simulation provided information for sensitivity of the DC as well as preferable dimensions of single mode waveguides. The result suggests that lengthening the DC improves its sensitivity. Another approach to realize high sensitivity was to make the coupling region of the DC longer for a given complete coupling length Lc. A folded DC is also presented based on calculations using Si waveguides. Here a meander-line with an array of segmented DCs and asymmetric 180°-curved waveguides was accommodated in a (100 μm)2 square area. Phases of propagating lights within two curved waveguides could be coincided. This cascade-connection of the segments of the DCs facilitated highly sensitive detection of biomolecules and a flexible sensor design. Signal dependences on device length and bulk RI change were evaluated by end-fire coupling measurements. The optical intensities agreed well with the corresponding fitting curve and the curve calculated based on the coupled mode theory.

Original languageEnglish
Title of host publicationFrontiers in Biological Detection
Subtitle of host publicationFrom Nanosensors to Systems VIII
EditorsSharon M. Weiss, Amos Danielli, G. Logan Liu, Benjamin L. Miller, Brian T. Cunningham
PublisherSPIE
ISBN (Electronic)9781628419597
DOIs
Publication statusPublished - 2016
EventFrontiers in Biological Detection: From Nanosensors to Systems VIII - San Francisco, United States
Duration: 14 Feb 201615 Feb 2016

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume9725
ISSN (Print)1605-7422

Conference

ConferenceFrontiers in Biological Detection: From Nanosensors to Systems VIII
Country/TerritoryUnited States
CitySan Francisco
Period14/02/1615/02/16

Keywords

  • Aptamer hybridization
  • Asymmetric silicon waveguide
  • Biological sensing
  • Interferometry
  • Silicon nitride directional coupler

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