FEM Modeling of Nanostructures for Sensor Application
A theoretical comparison of the optical and electronic properties of metallic nanostructures characterized by complementary geometries is proposed in this work. Periodic array of nanoparticles on glass substrate and nano-holes on metal substrate have been
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Introduction
In the last years, many theoretical and experimental studies have been made on metal nanoparticles because of their possible applications as chemical and biological sensor [1]. Significant attention has been paid in particular to Localized Surface Plasmon Resonance modes (LSPR) that gold and silver nanostructures are able to support when excited by incident light under specific conditions [2–5]. When the frequency of the light photons matches the frequency of surface plasmon polaritons (SPP), strong enhancements of the absorption, scattering and local electric field around the metal particles arise and the feature strongly depends on the material, the particle size, shape and distribution onto the substrate. These non-propagating plasma oscillations are strictly related to the optical properties of the local environment, allowing real-time monitoring of molecular adsorption occurring at metal/ dielectric interface with potential applications in gas and biosensing. Extensive research has been reported in the area of LSPR-based optical sensor, with the aim of sensitivity enhancement and detection limit reduction owing to the great enhancement of electromagnetic field near the surface of these nanostructures. New design and fabrication strategy of plasmonic transductors have been proposed in the last years in order to enhance the sensing performances and reproducibility of this optical sensors [6, 7].
A. Colombelli (*) CNR, Institute for Microelectronics and Microsystems, Unit of Lecce, Lecce, Italy Department of Innovation Engineering, University of Salento, Lecce, Italy e-mail: [email protected] M.G. Manera • R. Rella CNR, Institute for Microelectronics and Microsystems, Unit of Lecce, Lecce, Italy L. Vasanelli Department of Mathematics and Physics, University of Salento, Lecce, Italy C. Di Natale et al. (eds.), Sensors and Microsystems: Proceedings of the 17th National Conference, Brescia, Italy, 5-7 February 2013, Lecture Notes in Electrical Engineering 268, DOI 10.1007/978-3-319-00684-0_55, © Springer International Publishing Switzerland 2014
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Since advances in manufacturing techniques lead to a very precise control of structural dimensions, periodic arrays of metal nanoparticles have recently received considerable attention. When metal nanoparticles are brought into close proximity to each other, the resonance modes they support may interact modifying both the resonance shape and frequency of the LSPRs [8]. As recently demonstrated [9], also single and periodic array of nano-holes generated on the surface of thin metallic films may support LSPRs showing, under appropriate conditions, extraordinary optical transmission properties. These periodic arrays of nanostructures provide a very interesting platform for the development of detection devices with high sensitivity. However, the enhancement of LSPR sensors’ performances needs a careful optimization of the nanostructured transductors fabricated with precise geometries and sharp resonances. Followi
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