Multi-resonant plasmonic nanodome arrays for label-free biosensing applications

Abstract

The characteristics and utility of plasmonic nanodome arrays capable of supporting multiple resonance modes are described. A low-cost, large-area replica molding process is used to produce, on flexible plastic substrates, two-dimensional periodic arrays of cylinders that are subsequently coated with SiO2 and Ag thin films to form dome-shaped structures, with 14 nm spacing between the features, in a precise and reproducible fashion. Three distinct optical resonance modes, a grating diffraction mode and two localized surface plasmon resonance (LSPR) modes, are observed experimentally and confirmed by finite-difference-time-domain (FDTD) modeling which is used to calculate the electromagnetic field distribution of each resonance around the nanodome array structure. Each optical mode is characterized by measuring sensitivity to bulk refractive index changes and to surface effects, which are examined using stacked polyelectrolyte layers. The utility of the plasmonic nanodome array as a functional interface for biosensing applications is demonstrated by performing a bioassay to measure the binding affinity constant between protein A and human immunoglobulin G (IgG) as a model system. The nanoreplica molding process presented in this work allows for simple, inexpensive, high-throughput fabrication of nanoscale plasmonic structures over a large surface area (120 × 120 mm(2)) without the requirement for high resolution lithography or additional processes such as etching or liftoff. The availability of multiple resonant modes, each with different optical properties, allows the nanodome array surface to address a wide range of biosensing problems with various target analytes of different sizes and configurations.

Periodically Varying Height in Metal Nano-pillars for Enhanced Generation of Localized Surface Plasmon Field

“…The enhancement in LSPR field condition due to coupling of electromagnetic wave depends on how metal nanostructures have been patterned. Most of the works, related to the enhancement of LSPR field condition in metal nanostructures, which have been demonstrated so far were based on metal nano-pillars [9][10][11], nano-domes [12][13][14], sharp metal nanotips [15][16][17][18][19] and nano-clusters [5,6,20,21]. All such metal nanostructures provide tightly bound, highly intense localized plasmonic fields that interact strongly and scatter modulated LSPR signal whenever any external medium or bio-molecular sample comes into its vicinity.…”

Lasing Emission from Plasmonic Nanodome Arrays

“…[22] The PNDA devices have been successfully implemented for biological and chemical detection, such as surface-enhanced Raman scattering and label-free refractometric sensing. [22][23][24][25][26] For a PNDA structure, the LSP mode is generated by the dipole-dipole coupling between the adjacent nano-domes. In contrast, the SPP-BW mode is caused by the periodic structure of the PNDA.…”

Multiresonant layered plasmonic films

“…Furthermore, this technique allows us to independently design singly resonant films with precisely tailored properties that combine when stacked to form spectrally complex films. In contrast, other techniques to produce single layers of multiresonant plasmonic films require additional fabrication steps such as replica molding to fabricate a patterned surface or sequential deposition of nanospheres, 19,20 adding to the overall cost and time of fabrication. We conclude with the characterization and discussion of multiresonant plasmonic films for applications requiring unique spectral signatures.…”