Self‐Organized Hexagonal‐Nanopore SERS Array

Abstract

A real-time label-free detection method is in critical demand for biological, chemical, and medical applications, and environmental monitoring. Surface-enhanced Raman spectroscopy (SERS) is one of the best label-free detection methods. [1][2][3] Accordingly, a variety of fabrication methods of SERS substrates have been demonstrated. [4][5][6] Among the many such fabrication methods, self-assembly of nanoparticles is dominant. However, due to the uncontrollable bottom-up approach, the self-assembly method forms random hot spots for electromagnetic (EM) field enhancement. [6] Since the disordered random hot spots cause a nonuniform response of SERS signals, it is required to find a solution for forming precisely predetermined, reproducible, and organized nanoarchitectures for SERS substrates. For these purposes, focused-ion-beam [7,8] and electron-beam lithography [9] were applied for precision nanopatterning with the advantage of high resolution without the need for a physical mask, since the pattern can be changed at any time by using computer-aided design (CAD) software. However, the disadvantages of these two methods are the long exposure time due to pixel-by-pixel scanning steps, high cost, and substantial maintenance. To overcome these limitations, phase-shift lithography, [10] nanosphere lithography, [11] andcommunications Figure 5. Uniform SERS spectra on the nanopore SERS array. The spectra were measured at 15 different positions on a 4 cm 2 area of AAO coated with 20 nm Au; t AAO ¼ 100 nm and D nc ¼ 32 nm. Variation in the SERS spectra was well below 10%.

Engineering the plasmon resonance of large area bimetallic nanoparticle films by laser nanostructuring for chemical sensors

“…One of the major challenges in device fabrication is the production of uniform MNFs over large area substrates and repeatable tune-ability of their surface plasmon resonances (SPR). The maximum energy coupling in SERS coincides with the wavelength of the metal nanoparticles SPR and is localized at "hotspots" [7,9,10].Changes in the SPR optical absorption due to different composition of Ag and Au in alloy nanoparticles has been demonstrated previously [11,12]. The effect is attributed to the change in the dielectric function of the alloy nanoparticles from the volumetric contributions of Ag and Au.…”

“…One of the major challenges in device fabrication is the production of uniform MNFs over large area substrates and repeatable tune-ability of their surface plasmon resonances (SPR). The maximum energy coupling in SERS coincides with the wavelength of the metal nanoparticles SPR and is localized at "hotspots" [7,9,10].…”

Plasmonic nanopore-based platforms for single-molecule Raman scattering

“…SERS offers rich structural information and is undoubtedly one of the most promising label-free detection techniques. To date, few works have been done concerning fluidic plasmonic nanopore sensing, although nanoporebased SERS substrates were demonstrated [9,10]. Also, in Refs.…”

Morphology Dependence on Surface-Enhanced Raman Scattering Using Gold Nanorod Arrays Consisting of Agglomerated Nanoparticles

“…To overcome these problems, phase-shift lithography [7], nanosphere-assisted lithography [8], and nonlithographic self-organized nanoscale templating approaches [9] have been introduced as effective fabrication methods for plasmonic devices or SERS substrates. Among the nonlithographic fabrication techniques for SERS substrates, the self-organized anodized aluminum oxide (AAO) has attracted great interest due to relatively long-range ordering of pores and facile controllability of various configuration shapes [10][11][12][13].…”