Influence of the evanescent field decay length on the sensitivity of plasmonic nanodisks and nanoholes

Francesco Mazzotta, Timothy W. Johnson, Andreas B. Dahlin, Jonah Shaver, Sang Hyun Oh, Fredrik Höök

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

We evaluate and compare the sensitivity of gold nanodisks on silica substrates and nanoholes made in silica-supported gold films, two of the most common sensor structures used in plasmonic biosensing. An alumina overcoat was applied by atomic layer deposition (ALD) to precisely control the interfacial refractive index and determine the evanescent plasmonic field decay length. The results are in good agreement with analytical models and biomolecular binding experiments for the two substrates. We found that nanodisks outperform nanoholes for thin dielectric coatings (<∼20 nm), while the opposite holds true for thicker coatings (>∼20 nm). The optimum nanoplasmonic transducer element for a given biorecognition reaction can be chosen based on experimentally determined bulk sensitivities/noise levels and theoretically estimated evanescent field decay lengths.

Original languageEnglish (US)
Pages (from-to)256-262
Number of pages7
JournalACS Photonics
Volume2
Issue number2
DOIs
StatePublished - Feb 18 2015

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

Keywords

  • atomic layer deposition
  • biosensing
  • nanodisk
  • nanohole
  • plasmonics
  • surface plasmon resonance

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