SEMICONDUCTOR METHOD OF DETERMINING OXYGEN MICROCONCENTRATIONS IN DIFFERENT GASES

The ability of metal oxides to change their electric conductivity reversibly on variations of the partial pressure of oxygen has been utilized for the development of a sensor for analysis of oxygen in different gases. Data are considered on the dependence of electric conductivity on oxygen concentration, which is essential for selection of an optimal metal oxide. Various detection principles based on the adsorption and absorption of oxygen; various types of sensors using oxidized foil, thin films and sintered powder columns; and various methods (equilibrium, kinetic, and continuous) for measuring oxygen concentrations are proposed. Studies have been made of the main characteristics of the sensors in detecting oxygen in hydrogen, nitrogen, ethylene and inert gases. Various designs of gas-analyser sensors have been developed, with due consideration of their operation under conditions of variable pressures and temperatures of gases and with the aim of minimizing the preparation and response times. The results of industrial tests of the sensors are presented. © 1990.