title: Real-time and full-field detection of near-wall salinity using surface plasmon resonance reflectance.
abstract: An idea of real-time and full-field detection of near-wall salinity is presented to use the surface plasmon resonance (SPR) reflectance that changes with refractive index variations of the tested saline fluid. The laboratory-designed SPR system, based on the Kretschmann's configuration, uses a 47.5 nm thick gold layer as the SPR resonator, coated on a BK7 prism (n=1.515), and requires a one-time system calibration to establish a correlation of the specified saline mass concentration levels to the corresponding CCD (charge-coupled device) pixel gray levels. As a gravity-falling saline drop in water reaches the bottom and diffuses thereafter, the SPR system quantitatively maps the evolution of the salinity distributions in the near-wall region (less than 1 microm). An elaborate uncertainty analysis shows that the overall measurement uncertainties critically depend on the uniformity of the metal film thickness and the accuracy of its dielectric constant.
authors.affiliation: Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, Tennessee 37996-2210, USA.
authors.forename: Il Tai
authors.initials: IT
authors.lastname: Kim
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Kihm