Refractive index sensitivity of Au nanostructures in solution and on the substrate

AbstractIn this work, we present the synthesis and surface immobilization of Au nanostars, Au nanocubes and Au nanorods for localized surface plasmon resonance (LSPR)-based refractometric sensing applications. Au nanostructures exhibiting LSPR peak positions in 500–900 nm spectral range were prepared by seed-mediated synthesis method. The refractive index (RI) sensitivity of all these nanostructures in the colloidal solution were measured and the sample exhibiting highest sensitivity in each category were immobilized on the glass substrate. The surface immobilized nanostructures were investigated for RI sensing. Au nanostars having LSPR peak position at 767 nm exhibited highest RI sensitivity of 484 nm/RIU in solution and 318 nm/RIU on the substrate. This study gives an outline for selecting the Au nanostructures for developing plasmonic sensing platforms.

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Plasmonic coupling in Au, Ag and Al nanosphere homo-dimers for sensing and SERS

Advanced Electromagnetics ◽

10.7716/aem.v7i2.563 ◽

2018 ◽

Vol 7 (2) ◽

pp. 83-90 ◽

Cited By ~ 7

Author(s):

J. Katyal

Keyword(s):

Refractive Index ◽

Near Field ◽

Visible Region ◽

Field Enhancement ◽

Interparticle Spacing ◽

Localized Surface Plasmon ◽

Refractive Index Sensitivity ◽

Plasmonic Material ◽

Sensing Applications ◽

Index Sensitivity

The localized surface plasmon resonance of homo-dimer nanostructures is studied using FDTD simulations. The calculated LSPR wavelength of Au, Ag and Al nanosphere forming a homo-dimer configuration is compared and the results reveal a larger LSPR shift in Ag and Al homo-dimer than in Au homo-dimer. Taking the sensitivity of LSPR shape to the size and interparticle spacing of nanoparticle along with a surrounding refractive index, parameters like refractive index sensitivity have been determined. The spherical homo-dimer over the whole range of particle size, studied here shows the index sensitivity order as Ag>Al>Au. Hence, the use of plasmonic material towards the refractive index sensing applications is useful in this order. The average refractive index sensitivities of Ag, Al and Au are 287.09 nm/RIU, 210.21 nm/RIU and 192.47 nm/RIU in DUV-Visible-NIR region. Apart from LSPR shift, the highly confined near-field intensity enhancement of homo-dimer nanostructures for SERS has also been studied. The interacting homo-dimer nanoparticles reveals intensity enhancements in the junction. Comparing the field enhancement for Au, Ag and Al homo-dimer nanostructure 10^8-10^9 have been theoretically predicted in DUV-UV-visible region which can be used to strongly enhance the Raman scattering of molecules.

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Dewetting Metal Nanofilms—Effect of Substrate on Refractive Index Sensitivity of Nanoplasmonic Gold

Nanomaterials ◽

10.3390/nano9111530 ◽

2019 ◽

Vol 9 (11) ◽

pp. 1530 ◽

Cited By ~ 4

Author(s):

Nikhil Bhalla ◽

Aditya Jain ◽

Yoonjoo Lee ◽

Amy Q. Shen ◽

Doojin Lee

Keyword(s):

Refractive Index ◽

Localized Surface Plasmon ◽

Metal Nanostructures ◽

Refractive Index Sensitivity ◽

Ceramic Substrates ◽

Sensing Applications ◽

Wide Range ◽

Metal Nanostructure ◽

Index Sensitivity ◽

Silicon Based

The localized surface plasmon resonance (LSPR) sensitivity of metal nanostructures is strongly dependent on the interaction between the supporting substrate and the metal nanostructure, which may cause a change in the local refractive index of the metal nanostructure. Among various techniques used for the development of LSPR chip preparation, solid-state dewetting of nanofilms offers fast and cost effective methods to fabricate large areas of nanostructures on a given substrate. Most of the previous studies have focused on the effect of the size, shape, and inter-particle distance of the metal nanostructures on the LSPR sensitivity. In this work, we reveal that the silicon-based supporting substrate influences the LSPR associated refractive index sensitivity of gold (Au) nanostructures designed for sensing applications. Specifically, we develop Au nanostructures on four different silicon-based ceramic substrates (Si, SiO2, Si3N4, SiC) by thermal dewetting process and demonstrate that the dielectric properties of these ceramic substrates play a key role in the LSPR-based refractive index (RI) sensitivity of the Au nanostructures. Among these Si-supported Au plasmonic refractive index (RI) sensors, the Au nanostructures on the SiC substrates display the highest average RI sensitivity of 247.80 nm/RIU, for hemispherical Au nanostructures of similar shapes and sizes. Apart from the significance of this work towards RI sensing applications, our results can be advantageous for a wide range of applications where sensitive plasmonic substrates need to be incorporated in silicon based optoelectronic devices.

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Nano-thick-dielectric encapsulation effects on the refractive index sensitivities of Ag plane-nanosphere-cluster sensors

Modern Physics Letters B ◽

10.1142/s021798491850080x ◽

2018 ◽

Vol 32 (08) ◽

pp. 1850080 ◽

Cited By ~ 1

Author(s):

Chao Ling Du ◽

Wan Chun Yang ◽

Sheng Peng ◽

Da Ning Shi

Keyword(s):

Refractive Index ◽

Localized Surface Plasmon ◽

Great Promise ◽

Sers Substrate ◽

Refractive Index Sensitivity ◽

Surface Enhanced Raman ◽

Equilateral Triangles ◽

Quadratic Response ◽

The Stability ◽

Index Sensitivity

The nano-thick-dielectric encapsulation effects on the bulk and local refractive index sensitivity behaviors of Ag plane-nanosphere-cluster sensors (including nanosphere monomers, dimers, trimer chains and trimer equilateral triangles, four kinds of normally encountered nanoparticles in experiments) have been numerically investigated by finite element method (FEM). The encapsulation is revealed to decrease the quadratic magnitude of the refractive index responses of their peak wavelengths of localized surface plasmon resonances (LSPR), while it does not violate such quadratic response natures. Its effect on their capabilities of surface enhanced Raman scattering (SERS) behaviors is discussed too. It is demonstrated to provide an efficient type of SERS substrate for plasmonic sensing and detections, which improves the stability of the concerned nanoparticles, and not diminish their SERS signals, in agreement well with experiments under the same nanostructure parameters. This work holds great promise for further designing SERS-based sensing/detecting substrates and sensors/detectors.

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Double-exponential refractive index sensitivity of metal–semiconductor core–shell nanoparticles: the effects of dual-plasmon resonances and red-shift

RSC Advances ◽

10.1039/c7ra11981j ◽

2018 ◽

Vol 8 (3) ◽

pp. 1700-1705 ◽

Cited By ~ 7

Author(s):

Hailong Zhang ◽

Pengfei Cao ◽

Jie Dou ◽

Lin Cheng ◽

Tiaoming Niu ◽

...

Keyword(s):

Refractive Index ◽

Red Shift ◽

Localized Surface Plasmon ◽

Core Shell ◽

Refractive Index Sensitivity ◽

Shell Nanoparticles ◽

Double Exponential ◽

New Type ◽

Index Sensitivity ◽

Core Shell Nanoparticles

We present a new type of localized surface plasmon resonance (LSPR) sensor whose refractive index sensitivity can be improved by greatly increasing the plasmon wavelength red-shift of metal–semiconductor core–shell nanoparticles (CSNs).

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Facile Tuning and Refractive Index Sensitivity of Localized Surface Plasmon Resonance Inflection Points in Hollow Silver Nanoshells

Plasmonics ◽

10.1007/s11468-020-01277-6 ◽

2020 ◽

Author(s):

Jagmeet Singh Sekhon

Keyword(s):

Refractive Index ◽

Surface Plasmon Resonance ◽

Surface Plasmon ◽

Plasmon Resonance ◽

Localized Surface Plasmon Resonance ◽

Localized Surface Plasmon ◽

Refractive Index Sensitivity ◽

Inflection Points ◽

Silver Nanoshells ◽

Index Sensitivity

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Optical Micro/Nanofiber-Based Localized Surface Plasmon Resonance Biosensors: Fiber Diameter Dependence

Sensors ◽

10.3390/s18103295 ◽

2018 ◽

Vol 18 (10) ◽

pp. 3295 ◽

Cited By ~ 7

Author(s):

Kaiwei Li ◽

Wenchao Zhou ◽

Shuwen Zeng

Keyword(s):

Surface Plasmon Resonance ◽

Surface Plasmon ◽

Plasmon Resonance ◽

Performance Optimization ◽

Localized Surface Plasmon Resonance ◽

Fiber Diameter ◽

Localized Surface Plasmon ◽

Refractive Index Sensitivity ◽

Sensing Applications ◽

Index Sensitivity

Integration of functional nanomaterials with optical micro/nanofibers (OMNFs) can bring about novel optical properties and provide a versatile platform for various sensing applications. OMNFs as the key element, however, have seldom been investigated. Here, we focus on the optimization of fiber diameter by taking micro/nanofiber-based localized surface plasmon resonance sensors as a model. We systematically study the dependence of fiber diameter on the sensing performance of such sensors. Both theoretical and experimental results show that, by reducing fiber diameter, the refractive index sensitivity can be significantly increased. Then, we demonstrate the biosensing capability of the optimized sensor for streptavidin detection and achieve a detection limit of 1 pg/mL. Furthermore, the proposed theoretical model is applicable to other nanomaterials and OMNF-based sensing schemes for performance optimization.

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Numerical investigation of the refractive index sensitivity of au/Ag core-shell nanostructures (for sensing applications)

Sensing and Bio-Sensing Research ◽

10.1016/j.sbsr.2021.100414 ◽

2021 ◽

pp. 100414

Author(s):

Géza Szántó ◽

István Csarnovics ◽

Attila Bonyár

Keyword(s):

Refractive Index ◽

Numerical Investigation ◽

Core Shell ◽

Refractive Index Sensitivity ◽

Shell Nanostructures ◽

Sensing Applications ◽

Index Sensitivity

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Growth Kinetics and Sensing Features of Colloidal Silver Nanoplates

Journal of Nanomaterials ◽

10.1155/2019/7084731 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Giuseppe Compagnini ◽

Marcello Condorelli ◽

Maria E. Fragalà ◽

Vittorio Scardaci ◽

Ilaria Tinnirello ◽

...

Keyword(s):

Refractive Index ◽

Localized Surface Plasmon ◽

Refractive Index Sensitivity ◽

Silver Nanoplates ◽

Nanoparticle Shape ◽

Colloidal Form ◽

Aspect Ratios ◽

Resonance Band ◽

Infrared Spectral ◽

Index Sensitivity

This paper presents the growth mechanisms and the plasmon sensing features for a large class of silver nanoplates obtained in the colloidal form. The synthesis is conducted by seed-mediated growth and leads to plates with aspect ratios as large as 20, having localized surface plasmon resonances extending deeply into the infrared spectral region (1000 nm and above). We measure plasmon sensitivity by varying the colloidal local refractive index, and Δλ/Δn sensitivity values up to 500 nm/RIU are obtained. Theoretical considerations regarding the correlation between the refractive index sensitivity and the position of the main localized plasmon resonance band demonstrate that plasmon sensitivity does not depend directly on the nanoparticle shape and aspect ratio.

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