Nanoporous waveguides as versatile, high-sensitivity biosensors

K. H. A. Lau, P. J. Cameron, H. Duran, Ahmed Ibrahim Abou-Kandil, W. Knoll

Research output: Chapter in Book/Report/Conference proceedingChapter

5 Citations (Scopus)


This chapter introduces the application of nanoporous oxide thin films as optical waveguides for high-sensitivity biosensing. We discuss the waveguiding properties of nanoporous oxide thin films in the visible wavelengths when pore dimensions are much smaller (<1/10) than the guided light, and we show that the refractive index of such a nanopore-oxide matrix composite film is very well described by effective medium theory (EMT). Moreover, the optical response arising from binding of an analyte to a (suitably functionalized) nanoporous thin film is also described by EMT and forms the basis of analysis for high-sensitivity biosensing. Recent results on probing the sensitivity limits of label-free detection and the characterization of different molecular architectures are also presented. Particular attention is paid to the ability to differentiate, in situ, processes that occur on pore surfaces from those occurring on the top surface of the film. Moreover, we were able to directly measure the permeation of proteins within a nanoporous structure by simultaneous in-situ waveguide and electrochemical measurements.
Original languageEnglish
Title of host publicationSurface Design
Subtitle of host publicationApplications in Bioscience and Nanotechnology
EditorsRenate Foerch, H. Schoenherr, A. Tobias A. Jenkins
Place of PublicationWeinheim
Number of pages19
Publication statusPublished - 9 Sep 2009


  • effective medium theory (EMT)
  • nanoporous thin films
  • waveguide biosensors
  • nanoporous oxide thin-film waveguides
  • nanoporous AAO
  • optical waveguide spectroscopy (OWS)


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