The development of fiberoptic sensors for remote in-situ environmental monitoring using surface-enhanced Raman scattering (SERS) is described. The approach to sensor development includes the initial development of SERS-active media on nanoparticle-based solid-surface substrates. These media are generally metal-coated nanoparticles that can be further modified for enhanced chemical selectivity, longevity and ruggedness. One example of surface modification is the application of a permeability-selective polymer, polyvinyl pyrrolidone (PVP). For remote environmental sensing applications, the planar solid SERS substrates have been successfully incorporated in a two-fiber probe design. We have also applied SERS-active media directly to an optical fiber as an integrated single-fiber design. Such sensors occupy much less volume and promote non intrusive monitoring systems. Linear response of the integrated sensor monitoring systems for various environmental chemicals with excellent correlation (greater than 0.99) has been observed in the part-per-billion (ppb) range.
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