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Narrow groove plasmonic nano-gratings for surface plasmon resonance sensing.

Dhawan A, Canva M, Vo-Dinh T - Opt Express (2011)

Bottom Line: We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration.Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems.Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.

ABSTRACT
We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration. This eliminates the angular dependence requirements of SPR-based sensing and allows development of robust miniaturized SPR sensors. Simulations based on Rigorous Coupled Wave Analysis (RCWA) were carried out to numerically calculate the reflectance - from different gold and silver nano-grating structures - as a function of the localized refractive index of the media around the SPR nano-gratings as well as the incident radiation wavelength and angle of incidence. Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems. Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

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Rigorous coupled wave analysis (RCWA) calculations showing reflectance curves with localized refractive index around the film being 1.33 in green and 1.53 (n=1.53 for 1 nm above the metallic film, the remaining region having n=1.33) in blue for a planar metallic film (50 nm plasmonics-active metal and 5 nm Ti) deposited on a BK7 glass prism employed for SPR measurements. Reflectance and differential reflectance plots for angular interrogation are provided, the plasmonic metal being (a) Gold and (b) Silver. Reflectance and differential reflectance plots are provided for spectral interrogation, the plasmonic metal being (c) Gold and (d) Silver. RCWA calculations showing reflectance curve (differential reflectance in red, reflectance curves with localized refractive index around the grating n=1.33 in green and with n = 1.53 in blue) for a narrow groove metallic nano-grating (with 100 nm height and periodicity as well as 7 nm groove width) for a 1nm binding of target (refractive index = 1.53) on the surface of the metallic film for (e) Gold nano-grating, and (f) Silver nano-grating.
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g002: Rigorous coupled wave analysis (RCWA) calculations showing reflectance curves with localized refractive index around the film being 1.33 in green and 1.53 (n=1.53 for 1 nm above the metallic film, the remaining region having n=1.33) in blue for a planar metallic film (50 nm plasmonics-active metal and 5 nm Ti) deposited on a BK7 glass prism employed for SPR measurements. Reflectance and differential reflectance plots for angular interrogation are provided, the plasmonic metal being (a) Gold and (b) Silver. Reflectance and differential reflectance plots are provided for spectral interrogation, the plasmonic metal being (c) Gold and (d) Silver. RCWA calculations showing reflectance curve (differential reflectance in red, reflectance curves with localized refractive index around the grating n=1.33 in green and with n = 1.53 in blue) for a narrow groove metallic nano-grating (with 100 nm height and periodicity as well as 7 nm groove width) for a 1nm binding of target (refractive index = 1.53) on the surface of the metallic film for (e) Gold nano-grating, and (f) Silver nano-grating.

Mentions: The narrow groove nano-grating based SPR sensors are substantially different from conventional SPR sensors that employ the Kretschmann or Otto configurations. They do not require any prism coupling mechanism and are based on normal incidence of radiation on the sensor surface. This removes the stringent coupling angle requirements as in the conventional Kretschmann based SPR sensors and can also enable miniaturization of these sensors. Along with these advantages, we also observe from Fig. 2Fig. 2


Narrow groove plasmonic nano-gratings for surface plasmon resonance sensing.

Dhawan A, Canva M, Vo-Dinh T - Opt Express (2011)

Rigorous coupled wave analysis (RCWA) calculations showing reflectance curves with localized refractive index around the film being 1.33 in green and 1.53 (n=1.53 for 1 nm above the metallic film, the remaining region having n=1.33) in blue for a planar metallic film (50 nm plasmonics-active metal and 5 nm Ti) deposited on a BK7 glass prism employed for SPR measurements. Reflectance and differential reflectance plots for angular interrogation are provided, the plasmonic metal being (a) Gold and (b) Silver. Reflectance and differential reflectance plots are provided for spectral interrogation, the plasmonic metal being (c) Gold and (d) Silver. RCWA calculations showing reflectance curve (differential reflectance in red, reflectance curves with localized refractive index around the grating n=1.33 in green and with n = 1.53 in blue) for a narrow groove metallic nano-grating (with 100 nm height and periodicity as well as 7 nm groove width) for a 1nm binding of target (refractive index = 1.53) on the surface of the metallic film for (e) Gold nano-grating, and (f) Silver nano-grating.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368305&req=5

g002: Rigorous coupled wave analysis (RCWA) calculations showing reflectance curves with localized refractive index around the film being 1.33 in green and 1.53 (n=1.53 for 1 nm above the metallic film, the remaining region having n=1.33) in blue for a planar metallic film (50 nm plasmonics-active metal and 5 nm Ti) deposited on a BK7 glass prism employed for SPR measurements. Reflectance and differential reflectance plots for angular interrogation are provided, the plasmonic metal being (a) Gold and (b) Silver. Reflectance and differential reflectance plots are provided for spectral interrogation, the plasmonic metal being (c) Gold and (d) Silver. RCWA calculations showing reflectance curve (differential reflectance in red, reflectance curves with localized refractive index around the grating n=1.33 in green and with n = 1.53 in blue) for a narrow groove metallic nano-grating (with 100 nm height and periodicity as well as 7 nm groove width) for a 1nm binding of target (refractive index = 1.53) on the surface of the metallic film for (e) Gold nano-grating, and (f) Silver nano-grating.
Mentions: The narrow groove nano-grating based SPR sensors are substantially different from conventional SPR sensors that employ the Kretschmann or Otto configurations. They do not require any prism coupling mechanism and are based on normal incidence of radiation on the sensor surface. This removes the stringent coupling angle requirements as in the conventional Kretschmann based SPR sensors and can also enable miniaturization of these sensors. Along with these advantages, we also observe from Fig. 2Fig. 2

Bottom Line: We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration.Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems.Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.

ABSTRACT
We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration. This eliminates the angular dependence requirements of SPR-based sensing and allows development of robust miniaturized SPR sensors. Simulations based on Rigorous Coupled Wave Analysis (RCWA) were carried out to numerically calculate the reflectance - from different gold and silver nano-grating structures - as a function of the localized refractive index of the media around the SPR nano-gratings as well as the incident radiation wavelength and angle of incidence. Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems. Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

Show MeSH
Related in: MedlinePlus