Development and experiments with conductive oxide nanofilm coated planar waveguide sensors

Abstract

Due to the changes of the refractive indices, the planar optical waveguides are sensitive to the surrounding media, to the adsorbates, etc. on their surface. The sensitivity of such a waveguide layer can be enhanced when its thickness is lowered down to the nanometer range. Such sensors can be successfully operated both in inorganic chemistry and in life sciences as label free biosensors. Principles and some results are demonstrated. Further on, application of transparent conductive oxides for voltammetric measurements in combination with the classical waveguide sensor will be demonstrated. Development and results of a combined system is described and first results with simultaneous measurements are demonstrated. An indium tin oxide nanolayer is deposited and activated on the top of the sensor chip. This electrically conductive oxide layer serves as working electrode in the specially developed electrochemical cuvette. In this work results are presented for simultaneous use of these two methods and for simultaneous measurement of refractive index changes of the waveguiding system and that of electrical current changes. The first basic results are demonstrated using H2O2 and dye solutions, using KCl and TRIS as buffer and transport media.