Enhanced sensitivity of wavelength modulated surface plasmon resonance devices using dispersion from a dye solution

A dispersion technique for enhancing the sensitivity of wavelength modulate d surface plasmon resonance devices is presented. Using the dye, 1,1'3,3,3' ,3'-hexamethylindodicarbocyanine (HIDC) iodide, which contains a strong abs orption band centered in the dynamic range of the surface plasmon resonance coupling wavelength, the sensitivity to the bulk solution refractive index and the detection of analyte near the sensor surface is increased. A quant itative theory for the enhancement effect is derived from the fundamental e quation for surface plasmon resonance. Experimental results are presented f or a surface plasmon resonance fiber optic sensor. As much as a Lt-fold enh ancement in the sensitivity of the surface plasmon resonance response was o btained for bulk sucrose solutions, and a 2-fold enhancement was obtained f or binding of proteins to the sensor surface. The theoretical analysis show s that it should readily be possible to obtain significantly greater enhanc ements of the sensitivity. (C) 1999 Elsevier Science S.A. All rights reserv ed.