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

Abstract. We developed Hg 2þ -sensing chips by decorating the external surface of metal-clad optical wave-guides with a monolayer of Hg 2þ -sensitive fluorescent molecular probes. The emission properties of the originalwater-soluble form of the molecule were previously found to be selectively quenched in the presence of Hg 2þ ions. The fabricated samples were tested with optical waveguide fluorescence spectroscopy by putting them incontact with a 5-μM water solution of Hg 2þ ions and recording the emission spectra versus incubation time. Theestimate of the limit of detection was 150 nM. A preliminary evaluation of the selectivity of the structure wasalso performed by using Cd 2þ as possible interfering analytes. © 2014 Society of Photo-Optical Instrumentation Engineers(SPIE) [DOI: 10.1117/1.OE.53.7.071816] Keywords: optical sensors; photonics; lasers; plasmons; fluorescence spectroscopy.Paper 131650SS received Oct. 31, 2013; revised manuscript received Jan. 24, 2014; accepted for publication Jan. 27, 2014; pub-lished online Mar. 3, 2014.