The surface sensitivity of an optical waveguide is higher in the case of thin planar waveguides with a greater specific surface. The evanescent field of the light will detect the surface coating. Such optical waveguide lightmode sensors were developed on the basis of transparent Si_xTi_1-xO₂ layers with the necessary grating and can be successfully operated both in inorganic chemistry and in life sciences as label free biosensors. On the other hand, voltammetric and/or potentiometric electrochemical measurements also play paramount importance in the same and similar investigations. Since the optical waveguide lightmode detection method allows a label free approach in microbiological investigations with high sensitivity, presently the need of the combination of these mentioned two methods is of vital importance.

Si_xTi_1-xO₂ is a dielectric and the electrochemical measurements require a conducting electrode, thus, optically transparent, but conductive thin layer must be deposited on the grated optical sensor. Basically indium-tin-oxide (ITO) nanolayer covered chips were developed. At about 10 nm thick ITO layers show sufficiently good electrical conductivity and their good optical transparency corresponds to the requirements of the optical sensing. Outstanding sensibility of the ITO coated sensor chips on any surface modifications allows a highly attracting application of these layers.

It was demonstrated that the presence of the electrical field in an electrochemical cuvette incorporated into an integrated measuring instrument affects both the transport and the adsorption/desorption processes of the investigated species at the surface of the sensor. Lactic acid bacteria were adsorbed in native form on the surface of the sensor chips by ensuring polarizing potential (1 V) and were exposed to various chemical stressors and the behaviour of bacteria was monitored.

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1. Some Optical Effects on the Electrical Conductivity of ITO Nanoscale Layers
2. Combination of the Optical Waveguide Lightmode Spectroscopy Method with Electrochemical Measurements
3. Influence of Illumination and Decay of Electrical Resistance of ITO Nanoscale Layers
4. An RBS Study of Thin PLD and MOCVD Strontium Copper Oxide Layers
5. Surface Scattering Optical Loss Measurements in Thin Oxide Planar Waveguide Layers