<title>Novel multilayered SERS substrates for trace chemical and biochemical analysis</title>

Abstract

We have developed and characterized novel multilayered metal film-based surface-enhanced Raman scattering (SERS) substrates capable of enhancing SERS signals over an order of magnitude compared to conventional single layer substrates. In addition to enhanced signal intensity, these multilayered metal film substrates also exhibit longer SERS active lifetimes, higher reproducibility and lower detection limits than single layer silver substrates. Multilayered metal film substrates were fabricated by repeated vapor deposition of metal films over nanometer sized silica spheres. Different sizes of silica spheres were evaluated in order to obtain the optimal SERS enhancements. Meanwhile, different coating methods, drop coating and spin coating, were applied to form silica sphere layers that provided the roughness for SERS enhancements. These two coating methods were also compared for various silica sphere sizes by investigating their effects on the SERS enhancements. By applying additional silver layers on top of silver film over silica sphere SERS substrates, multi-layer enhancements can be observed. Additionally, different metals, such as gold, were used to further optimize the stability and reproducibility of these novel substrates. In order to speed up the fabrication of these multiple metal layer SERS substrates, silver oxide layers produced in an oven were investigated, reducing fabrication time by a factor of 50.

The development of Army relevant peptide-based surface enhanced Raman scattering (SERS) sensors for biological threat detection

“…Slides rotate during deposition to ensure a uniformly coated metal surface is produced. 38,89 Substrates were regenerated by depositing approximately 500nm of Au on the stripped Klarite surface. 1.9 Plasmon Data.…”

“…It is suggested that the reader look to several comprehensive reviews and interesting papers for a more complete discussion of SERS substrate fabrication techniques, applications, advantages and challenges. 1,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] One of the more common and easily achieved methods for the fabrication of SERS substrates is known as the drop and dry technique. Drop and dry techniques or Film over Nanosphere (FONS) offer some advantages as compared to other fabrication methods like ease of fabrication due to cheaper manufacturing materials, and often being lower cost in skill, time and overall materials as compared to some other more fabrication intensive techniques.…”

Targeting biological sensing with commercial SERS substrates

“…The more sensitive substrate platforms generally have a 15% relative standard deviation (RSD; the measure of the reproducibility of an analysis) from substrate-to-substrate and SERS signal enhancements of 7 to 8 orders of magnitude. (60,61) Consequently, many researchers in academia, industry, and government have focused concerted efforts toward increasing the signal enhancement ability, reproducibility, and mass production manufacturing of substrates to increase the utility of this technique. (5,67) For the Army and first responders, such a substrate platform with increased sensitivity and reliability would be very advantageous for the detection and identification of unknowns.…”

“…(48) Because of the many sensing advantages of SERS-based techniques, significant research efforts (defense, industrial and academic) have been directed toward fabricating "better" SERS substrates for SERS-based sensor platforms. (48)(49)(50)(51)(52)(53)(54)(55)(56)(57) Some of these SERS platforms are fabricated from colloids (58) , film over nanospheres (59)(60)(61)(62) , fiber optic bundles (3) , nanoparticles, (55,(63)(64)(65)(66) and lithographically (5) produced structures. The more sensitive substrate platforms generally have a 15% relative standard deviation (RSD; the measure of the reproducibility of an analysis) from substrate-to-substrate and SERS signal enhancements of 7 to 8 orders of magnitude.…”

Flexible SERS-based substrates: challenges and opportunities toward an Army relevant universal sensing platform

“…Some examples of SERS substrate fabrication include self-assembly through such techniques like drop and dry, directed or templated assembly, thin film growth, and nanolithography. It is suggested that the reader look to several comprehensive reviews and interesting papers for a more complete discussion of SERS substrate fabrication techniques, applications, advantages and challenges3,11,17,24,33,84,85,[108][109][110][111][112][113][114][115][116][117][118][119][120][121] .…”