Combination of the optical waveguide lightmode spectroscopy method with electrochemical measurements

• Published in: Thin solid films 2008-09, Vol.516 (22), p.8165-8169
• Main Authors: Szendrő, I., Erdélyi, K., Fábián, M., Puskás, Zs, Adányi, N., Somogyi, K.
• Format: Article
• Language: English
• Subjects: Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electrochemistry; Exact sciences and technology; General and physical chemistry; General equipment and techniques; Indium tin oxide; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Kinetics and mechanism of reactions; Lightmode spectroscopy; Microbiology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Planar optical waveguides; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Silicon titanium oxide; Transparent conductive oxides
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2008.04.065

Optical waveguides are normally sensitive to the surrounding media and also to the surface contaminations. The effective refractive index changes at the surface. Various sensor systems were developed based on this effect. One of the most sensitive and effective methods is the optical waveguide lightmode spectroscopy (OWLS). At the same time, electrochemical methods are widely used both in inorganic and organic chemistry, and also advantages in microbiology were demonstrated. In this work, efforts are made and results are presented for the combination of these two methods for simultaneous measurement of refractive index and electrical current changes caused by the presence of cells/molecules/ions to be investigated. An electrically conductive indium tin oxide (ITO) nanolayer is deposited and activated on the top of the OWLS planar waveguide oxide layer. ITO layers serve as working electrodes in the electrochemical measurements. The basic setup and an integrated system are demonstrated here. Measurements using H 2O 2, toluidine blue solutions, and KCl and TRIS solutions as buffer and transport media are represented. Measurements show both the changes detected by the sensor layer and the effect of the applied potential in cyclic and chrono voltammetric measurements. Results demonstrate an effective combination of optical and electrochemical methods.