Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 9. Incorporation of planar waveguide technology

Incorporation of planar waveguide technology into a spectroelectrochemical sensor is described. In this sensor design, a potassium ion-exchanged BK7 g lass waveguide was over-coated with a thin film of indium tin oxide (ITO) t hat served as an optically transparent electrode. A chemically selective fi lm was spin-coated on top of the ITO film. The sensor supported five optica l modes at 442 nm and three at 633 nm. Investigations on the impact of the ITO film on the optical properties of the waveguide and on the spectroelect rochemical performance of the sensor are reported. Sensing was based on the change in attenuation of light propagated through the waveguide resulting from an optically absorbing analyte, By applying either a triangular or squ are wave excitation potential waveform, electromodulation of the optical si gnal has been demonstrated with Fe(CN)(6)(3-/4-) as a model electroactive c ouple that partitions into a PDMDAAC-SiO2 film {where PDMDAAC = poly(dimeth yldiallylammonium chloride)} and absorbs at 442 nm.