Metal-clad optical waveguide fluorescence device for the detection of heavy metal ions

We developed Hg2+-sensing chips by decorating the external surface of metal-clad optical wave-guides with a monolayer of Hg2+-sensitive fluorescent molecular probes. The emission properties of the original water-soluble form of the molecule were previously found to be selectively quenched in the presence of Hg2+ ions. The fabricated samples were tested with optical waveguide fluorescence spectroscopy by putting them in contact with a 5- μ M water solution of Hg 2+ions and recording the emission spectra versus incubation time. The estimate of the limit of detection was 150 nM. A preliminary evaluation of the selectivity of the structure was also performed by using Cd 2+ as possible interfering analytes.