Stamping plasmonic nanoarrays on SERS‐supporting platforms

Abstract

The dielectric property of a nanoparticle-supporting film has recently garnered attention in the fabrication of plasmonic surfaces. A few studies have shown that the localized surface plasmon resonance (LSPR), and hence surface-enhanced Raman scattering (SERS), strongly depends on the substrate refractive index. In order to create higher efficiency SERS-active surfaces, it is therefore necessary to consider the substrate property along with nanoparticle morphology. However, due to certain limitations of conventional lithography, it is often not feasible to create well-defined plasmonic nanoarrays on a substrate of interest. Here, an additive nanofabrication technique, i.e., nanotransfer printing (nTP), is implemented to integrate electron beam lithography (EBL) defined high-aspect-ratio nanofeatures on a variety of SERS-supporting surfaces. With the aid of suitable surface chemistries, a wide range of plasmonic particles were successfully integrated on surfaces of three physically and chemically distinct dielectric materials, namely, polydimethyl siloxane (PDMS), SU-8 photoresist, and glass surfaces, using silicon-based relief pillars. These nTP-created metal nanoparticles strongly amplify the Raman signal and complement the selection of suitable substrates for better SERS enhancement. Our experimental observations are also supported by theoretical calculations. The implementation of nTP to stamp out metal nanoparticles on a multitude conventional/unconventional substrates has novel applications in designing in-built plasmonic microanalytical devices for SERS sensing and other related photonic studies. Copyright (C) 2011 John Wiley & Sons, Ltd

Surface-Enhanced Raman Scattering as an Emerging Characterization and Detection Technique

“…The evidence, that SERS can be used for single-molecule detection and clear understanding of the relationship between LSPR and SERS enhancement mechanism, has inspired many recent studies focused on design and fabrication of new types of SERS substrates [149][150][151].…”

“…A growing number of promising results on SERS active substrates prepared using lithographyderived processing have been reported more recently [18,[47][48][49][50][51][52][53][54][55][56][57][58].…”

“…Plasmonic dimers shaped as nanoscale bowtie antennas [54] represent another interesting class of structures that can be precisely fabricated using EBL and utilized as very promising high-performance SERS substrates [52]. These substrates were characterized by SERS enhancement factor exceeding 10 11 .…”

“…A relatively low throughput and high cost of EBL tools makes them less attractive for scaled-up fabrication of SERS substrates. In order to make deterministic patterning of SERS substrates scalable, more flexible and less expensive advantages of EBL can be further augmented by nanoimprinting, nanoembossing [70], and nanotransfer stamping/printing approaches [53,54]. For instance, a small-area silicon master with nanoscale patterns can be created using a combination of EBL and RIE and then used in a step-and-repeat process to pattern larger areas and/or a number of SERS substrates in a cost-and timeefficient manner.…”

Surface enhanced Raman spectroscopy (SERS) for in vitro diagnostic testing at the point of care

“…Due to the difficulty in reproducibly preparing nanostructures, many planar SERS substrates must be synthesized using a variety of sequential complex photolithographic techniques borrowed from the silicon wafer industry. These methods include techniques such as using electron beam deposition (EBD) to create the nanorough surface itself [90,119], using EBD to produce "nanostamps" [120], combining nanoimprint and copolymer lithographic techniques [121], using selfassembled nanoparticles (SAMs) [122,123], and many others using non-spherical particles such as Au-and Agcoated nanorod arrays [124,125]. These techniques, specifically EBD, produce high-resolution nanostructures that are reproducible within a wafer; however, there is a tradeoff with high reproducibility and low enhancement factor (10 2 - 10 4 ) [126].…”