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Open AccessArticle

Gold Nanopost-Shell Arrays Fabricated by Nanoimprint Lithography as a Flexible Plasmonic Sensing Platform

1
National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Str., 400293 Cluj-Napoca, Romania
2
Institute for Interdisciplinary Research in Bio-Nano-Sciences, Babes-Bolyai University, 42 T. Laurian, 400271 Cluj-Napoca, Romania
3
Faculty of Physics, Babes-Bolyai University, 1 M. Kogalniceanu, 400084 Cluj-Napoca, Romania
4
Electronic Microscopy Laboratory and Department of Molecular Biology and Biotechnology, Babeș-Bolyai University, 44 George Bilascu Street, 400015 Cluj-Napoca, Romania
*
Author to whom correspondence should be addressed.
Nanomaterials 2019, 9(11), 1519; https://doi.org/10.3390/nano9111519
Received: 15 September 2019 / Revised: 18 October 2019 / Accepted: 22 October 2019 / Published: 25 October 2019
(This article belongs to the Special Issue Nanoscale Optical Sensing)
Plasmonic noble metal nanostructured films have a huge potential for the development of efficient, tunable, miniaturized optical sensors. Herein, we report on the fabrication and characterization of gold-coated nanopost arrays, their use as refractometric sensors, and their optimization through photonics simulations. Monolithic square nanopost arrays having different period and nanopost size are fabricated by nanoimprint lithography on polymer foils, and sputter-coated by gold films. The reflectivity of these gold nanopost-shell arrays present dips in the visible range, which are efficient for refractometric sensing. By finite-difference time-domain (FDTD) simulations we reproduce the experimental spectra, describe the electric fields distribution around the nanopost-shells, and then explain their good sensitivity, around 450 nm/RIU. Furthermore, we determine by simulations the influence of several geometrical parameters, such as array period, nanopost width, gold film thickness, and nanopost side coverage on both reflectivity spectra and sensing capabilities. Fully coated nanoposts provide an extremely deep reflectivity minimum, approaching zero, which makes the relative reflectivity change extremely high, more than two orders of magnitude higher than for partially coated nanoposts. These results contribute to the understanding of the plasmonic properties of metal coated nanopost arrays, and to the development of efficient platforms for sensing and other surface plasmon based applications. View Full-Text
Keywords: surface plasmon; sensors; nanoposts; nanopillars; nanoimprint lithography; nanofabrication; finite-difference time-domain (FDTD) simulation surface plasmon; sensors; nanoposts; nanopillars; nanoimprint lithography; nanofabrication; finite-difference time-domain (FDTD) simulation
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MDPI and ACS Style

Farcau, C.; Marconi, D.; Colniță, A.; Brezeștean, I.; Barbu-Tudoran, L. Gold Nanopost-Shell Arrays Fabricated by Nanoimprint Lithography as a Flexible Plasmonic Sensing Platform. Nanomaterials 2019, 9, 1519.

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