Katarzyna Dunst

POTENTIOMETRIC OXYGEN SENSOR WITH SOLID STATE REFERENCE ELECTRODE

The concentration or the partial pressure of oxygen in an environment can be determined using different measuring principles. For high temperature measurements of oxygen, ceramic-based sensors are the most practical. They are simple in construction, exploration and maintenance. A typical oxygen potentiometric sensor consists of an oxygen ion conducting solid electrolyte and two electrodes deposited on the two sides of the electrolyte. In this paper different structures of potentiometric oxygen sensors with a solid state reference electrode were fabricated and investigated. The fabricated structures consisted of oxygen ion conducting solid electrolyte from yttria stabilized zirconia, a sensing platinum electrode and nickel-nickel oxide reference electrode. The mixture of nickel-nickel oxide was selected as the reference electrode because it provides reliable electrochemical potential in contact with oxygen conducting electrolyte. To avoid oxidation of nickel the reference electrode is sealed from ambient and the mixture of nickel-nickel oxide was formed electrochemically from nickel oxide after sealing. The effectiveness of the sealing quality and the effectiveness of nickel–nickel oxide mixture formation was investigated by impedance spectroscopy.

Polypyrrole based gas sensor for ammonia detection

The nature of polypyrrole response to toxic gases does not allow using the sensor in a conventional way. The main aim of this study is to acquire the information about the concentration using different approaches: a linear approximation, a non-linear approximation and a tangent method. In this paper a two-steps procedure for sensor response measurements has been utilized. Polypyrrole films were electrochemically synthesized on the interdigitated electrodes. Gas sensing measurements of polypyrrole based sensor were carried out at room temperature. The influence of the flow rate on the sensing performance to NH3 were investigated. The preliminary studies of aging of the sensor were also explored.

Graphene oxide, reduced graphene oxide and composite thin films NO2 sensing properties

A graphene oxide (GO), reduced graphene oxide (RGO) and poly(3,4-ethylenedioxytiophene)-reduced graphene oxide (PEDOT-RGO composite) gas sensors were successfully fabricated using an electro-deposition method. The electro-deposition was carried out in aqueous GO dispersions. To obtain RGO and PEDOT-RGO, the electrochemical reduction of GO and PEDOT-GO was carried out in 0.1 M KCl at a constant potential of −0.85 V. The GO, RGO and PEDOT-RGO composite were characterized by scanning electron microscopy (SEM). The fabricated sensors showed sensitivity to NO2 gas. In this work the sensing response of GO, RGO and PEDOT-RGO in NO2 at elevated temperatures were investigated. The influence of the operating temperature on the gas sensing response were compared. The role of the polymer and RGO in PEDOT-RGO composite was discussed. The results are discussed in light of recent literature on graphene sensors.