Influence of an Al2O3 surface coating on the response of polymeric waveguide sensors

Leila Ahmadi, Marianne Hiltunen, Jussi Hiltunen, Sanna Aikio, Jyrki Saarinen, Seppo Honkanen, Matthieu Roussey (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    4 Citations (Scopus)


    The responses of a polymer ridge waveguide Young interferometer with and without a bilayer of Al2O3/TiO2, fabricated by atomic layer deposition, are studied and compared when applied as an aqueous chemical sensor. The phase shift of the guided mode, as a result of the change in refractive index of the cover medium, is monitored. The results indicate that the over-coating affects the linearity of the sensor response. The effect of concentration on the linearity of the sensor response is investigated by applying different concentrations of water-ethanol solution. Although the performance of the sensor is improved by the additional layers, the study reveals a non-monotonic behavior of the device. We show that it comes mainly from the adsorption of ethanol molecules on the surface of the films. Such an understanding of the platform is crucial for sensing of analytes involving polar molecules.
    Original languageEnglish
    Pages (from-to)25102-25112
    JournalOptics Express
    Issue number21
    Publication statusPublished - 16 Oct 2017
    MoE publication typeA1 Journal article-refereed


    • atomic layer deposition
    • coatings
    • ethanol
    • molecules
    • polymers
    • refractive index
    • waveguides


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