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Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications

We investigate the effect of substrate etching on terahertz frequency range metamaterials using finite-element method simulations. A blue shift was found in the metamaterial resonance with increasing substrate etch depth, caused by a decrease in the effective refractive index. The relative contribut...

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Detalles Bibliográficos
Autores principales: Park, Sae June, Cunningham, John
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7308813/
https://www.ncbi.nlm.nih.gov/pubmed/32492949
http://dx.doi.org/10.3390/s20113133
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author Park, Sae June
Cunningham, John
author_facet Park, Sae June
Cunningham, John
author_sort Park, Sae June
collection PubMed
description We investigate the effect of substrate etching on terahertz frequency range metamaterials using finite-element method simulations. A blue shift was found in the metamaterial resonance with increasing substrate etch depth, caused by a decrease in the effective refractive index. The relative contribution of the substrate’s refractive index to the effective refractive index was obtained as a function of the etch depth, finding that the decay length of the electric field magnitude below the LC gap is larger for the etched metamaterials due to their lower effective refractive index. We suggest designs for a terahertz metamaterial liquid sensor utilizing substrate etching which shows a significant enhancement in sensitivity compared to unetched sensors using ethanol as an example analyte. The sensitivity of the liquid sensor was enhanced by up to ~6.7-fold, from 76.4 to 514.5 GHz/RIU, for an ethanol liquid layer with a thickness of 60 μm by the incorporation of a substrate etch depth of 30 µm. Since the region of space close to the metamaterial is the most sensitive, however, we find that for small liquid thicknesses, larger etch depths can act to decrease sensitivity, and provide quantitative estimates of this effect.
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spelling pubmed-73088132020-06-25 Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications Park, Sae June Cunningham, John Sensors (Basel) Letter We investigate the effect of substrate etching on terahertz frequency range metamaterials using finite-element method simulations. A blue shift was found in the metamaterial resonance with increasing substrate etch depth, caused by a decrease in the effective refractive index. The relative contribution of the substrate’s refractive index to the effective refractive index was obtained as a function of the etch depth, finding that the decay length of the electric field magnitude below the LC gap is larger for the etched metamaterials due to their lower effective refractive index. We suggest designs for a terahertz metamaterial liquid sensor utilizing substrate etching which shows a significant enhancement in sensitivity compared to unetched sensors using ethanol as an example analyte. The sensitivity of the liquid sensor was enhanced by up to ~6.7-fold, from 76.4 to 514.5 GHz/RIU, for an ethanol liquid layer with a thickness of 60 μm by the incorporation of a substrate etch depth of 30 µm. Since the region of space close to the metamaterial is the most sensitive, however, we find that for small liquid thicknesses, larger etch depths can act to decrease sensitivity, and provide quantitative estimates of this effect. MDPI 2020-06-01 /pmc/articles/PMC7308813/ /pubmed/32492949 http://dx.doi.org/10.3390/s20113133 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Letter
Park, Sae June
Cunningham, John
Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title_full Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title_fullStr Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title_full_unstemmed Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title_short Effect of Substrate Etching on Terahertz Metamaterial Resonances and Its Liquid Sensing Applications
title_sort effect of substrate etching on terahertz metamaterial resonances and its liquid sensing applications
topic Letter
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7308813/
https://www.ncbi.nlm.nih.gov/pubmed/32492949
http://dx.doi.org/10.3390/s20113133
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