Abstract: An electrochemical gas sensor having a solid ionic conductive electrolyte therein and adapted to sense trace levels of reactive gases in the parts per million range. The electrochemical sensing cell has a pair of catalytic electrodes attached to the opposite sides of the solid electrolyte. The sensing cell is supported and contained to permit the distribution of reactant gases over the electrode surfaces for reacting thereat and thereby providing an external electrical current flow representative of the quantity of the reactant gas undergoing sensing.

Abstract: An electrochemical gas sensor having a high surface area gas diffusing electrode defined for diffusing gases to be sensed to reach the catalyst surfaces of the electrode to provide the cathodic reduction of oxygen in a gas mixture undergoing sensing thereat. The sensor is adapted to sense trace levels of reactive gases in parts per billion. The sensor provides for ready purging of reactive gases from the electrolyte solution for the cell. The cell is essentially insensitive to the rate of flow of gas delivered to the cathode electrode and the minor mechanical stirring of the electrolyte solutions leading to output signals of improved signal-to-noise ratios more accurately signalling the concentrations of reactive gases, such as oxygen in gas mixtures.

Abstract: A method of making an electrochemical sensor is disclosed in which a liquid electrolyte such as sulfuric acid is blended with fumed silica in an amount sufficient to powderize the mixture. The resultant mixture is compacted under pressure between electrodes to form an electrochemical gas sensor.