Sensors based on monochromatic interrogation of a localised surface plasmon resonance

Abstract

The localised surface plasmon resonance in gold nanoparticles can be used as the basis of a refractometric sensor. Usually, this is accomplished by monitoring a shift in wavelength of the resonance peak, a task which requires measurements over a range of wavelengths. Here we investigate a different scheme, in which interrogation of the sensor is carried out at a single wavelength. We have used numerical simulations to estimate the effect that the shape of gold nanoparticles would have on the performance on such sensors. A variety of geometries of gold nanoparticles were investigated, including nano-spheres, nano-rods, nano-triangles, and nanobowties. The performance of a sensor that operates at a single wavelength is controlled by dT/dn, the change in transmittance T with refractive index n, determined at the interrogation wavelength. In turn, dT/dn depends upon the extinction cross-section of the nanoparticles at the chosen wavelength, and on the density of the nanoparticles in the light path. Contributions to the sensor efficiency also include the shift in wavelength of the plasmon resonance and, importantly, the peak sharpness. Of the particles examined, gold nanorods will provide the most sensitive sensors by a large margin.

Gold Nanoparticles in Chemical and Biological Sensing

“…14,309,883–895 Although numerous biosensors have been developed using silver nanoparticles 896–903 we will focus on AuNP based sensors. 894,904–915 …”

Influence of Cationic Surfactants on the Formation and Surface Oxidation States of Gold Nanoparticles Produced via Laser Ablation

“…Chemical synthesis is the most common technique to generate various sizes and shapes of gold nanoparticles. This involves the chemical reduction of a suitable starting material, such as HAuCl 4 or NaAuCl 4 , in aqueous solution along with organic molecules that act as stabilizers. ,, During the reduction process, different shapes of gold nanoparticles, including nanorods, nanotriangles, and nanospheres, , have been generated and their properties analyzed using various spectroscopic techniques. One of the most common stabilizers used for synthesizing spherical AuNPs are compounds containing thiol ligands .…”

Damping of Plasmons of Closely Coupled Sphere Chains Due to Disordered Gaps

“…Plasmonic resonances strongly concentrate electromagnetic fields, which can be exploited in a range of applications including those involving energy transport, 1,2 imaging, 3,4 and sensing. 5,6 The damping of plasmonic resonances usually reduces their performance in applications, and understanding this problem is of considerable practical importance. Damping mechanisms range from large-scale mechanisms such as radiative damping, to small-scale quantum mechanisms.…”

“…Plasmonic resonances strongly concentrate electromagnetic fields, which can be exploited in a range of applications including those involving energy transport, , imaging, , and sensing. , The damping of plasmonic resonances usually reduces their performance in applications, and understanding this problem is of considerable practical importance. Damping mechanisms range from large-scale mechanisms such as radiative damping, to small-scale quantum mechanisms. − Between these two extremes, the performance can be maximized within the limitations of the materials and fabrication techniques.…”