An integrated portable Raman sensor with nanofabricated gold bowtie array substrates for energetics detection

Abstract

An integrated field-portable surface enhanced Raman scattering (SERS) sensing system has been developed and evaluated for quantitative analysis of energetics such as perchlorate (ClO(4)(-)) and trinitrotoluene (TNT) at environmentally relevant concentrations and conditions. The detection system consists of a portable Raman spectrometer equipped with an optical fiber probe that is coupled with novel elevated gold bowtie nanostructural arrays as a sensitive and reproducible SERS substrate. Using the standard addition technique, we show that ClO(4)(-) and TNT can be quantified at concentrations as low as 0.66 mg L(-1) (or ~6.6 µM) and 0.20 mg L(-1) (~0.9 µM), respectively, in groundwater samples collected from selected military sites. This research represents the first step toward the development of a field SERS sensor which may permit rapid, in situ screening and analysis for various applications including national security, chemical, biological and environmental detection.

Surface-enhanced Raman scattering of perchlorate on cationic-modified silver nanofilms – Effect of inorganic anions

“…Surface-enhanced Raman scattering (SERS), as one of the most sensitive spectroscopic analysis methods, has been extensively investigated for chemical and biological sensing [8][9][10][11][12][13][14][15][16][17] including the possibility of detecting single molecules [18][19][20]. In particular, the combination of the SERS technique with commercially available portable/handheld Raman systems has shown great potential to meet the criteria of field assays of environmental pollutants including ClO 4 À ions [21][22][23][24][25][26]. It is well known that only the molecules which adsorb chemically or physically onto nanostructured substrates of noble metals (mostly Ag or Au) produce a significant SERS effect.…”

“…To solve this problem, two approaches have been used. One is to measure SERS spectra using samples air-dried on planar SERS substrates to deposit perchlorate onto nanostructured Ag or Au surfaces [22,29]. Another approach has been developed to chemically modify the SERS substrates, trapping and concentrating ClO 4 À anions onto Ag or Au surfaces [7,[30][31][32][33][34][35][36].…”

Biomedicine with surface enhanced Raman scattering (SERS)

“…The resultant dimer structure consists of two Ag nanospheres each $30 nm in diameter and separated by 1.8 nm "unfilled" gap in the solution phase (see Figure 5.4). The nanobowtie substrate shows a maximum SERS-EF of about 10 11 with a spot-to-spot variation of only about 10% based on SERS measurements of p-mercaptoaniline as a sample molecule (Hatab et al, 2010(Hatab et al, , 2011. of surface morphologies.…”

Clinical SERS: are we there yet?

“…Many often, a highly SERS-active NMP can become almost un-usable due mainly to the random distributions of hot-spot sites which bring about large spot-to-spot or batch-to-batch variations [100]. To this end, techniques such as laserablation [101], dip-pen nano-lithography [102], and e-beam lithography [103] have been imperative to producing reproducible SERS substrates with periodically arranged hot-spot distributions.…”