Development of an integrated single-fiber SERS sensor

An integrated fiberoptic surface-enhanced Raman scattering (SERS) sensor based on a single-fiber system is described and evaluated for remote and in situ measurements. The heart of the sensor consists of a unique single optical fiber designed to induce the SERS effect through the incorporation of alumina nanoparticles and silver coatings onto the probe tip. The unique design based on single-fiber for excitation/emission (SFEE) is practical for the fabrication of in situ sensors in microenvironments. Since the single fiber carries both the laser excitation and SERS signal radiation, optical parameters of the remote tip are simple and consistent. Depending on the tip size, the fiberoptic SERS sensor allows in situ measurements at microscale environments. Details of sensor tip Fabrication and optical system design are described. Two detection schemes can be used: a "dip-and-dry" mode of detection and an in situ sensing mode are demonstrated for several compounds, including cresyl fast violet (CFV), brilliant cresyl blue (BCB), p-aminobenzoic acid (PABA) and 3-aminopyrene (3AP). To illustrate the effectiveness of this new SERS sensor for remote in situ analysis, SERS spectra of aqueous dye samples (CFV and BCB) are presented. A quantitative calibration curve for CFV in groundwater is established and a limit of optical detection of approximately 50 ppb CFV in groundwater is determined. Published by Elsevier Science S.A.