Abstract: A sensing surface for a sensing cathode electrode useful in electrochemical gas sensors for sensing active gases in a gas mixture. The gas sensors are utilized in sensing oxygen or exhaust gases from a motor vehicle, so that there is a potential for causing deposits on the sensing surface of the electrode of either lead oxide species or lead carbonate thereon. The sensing surface is plated with rhodium or platinum for rejecting or prolonging the formation of any of the deposits thereon leading to an increase in rated life for the gas sensor greater than heretofore thought possible.

Abstract: An electrochemical gas analyzer is disclosed which includes sensing, compensation and counter electrodes in an electrolyte. The compensation electrode provides a compensation signal related to the concentration of gas dissolved in the bulk of the electrolyte. This compensation signal is subtracted from the analyzer output signal to eliminate errors caused by bulk electrolyte dissolved gas.

Abstract: An electrochemical cell (10) having a structural organization that permits it to operate as either a galvanic or polarographic cell. The structural organization includes an electrolyte reservoir (E) comprised of a solid-like material such as a gel to releasably hold a liquid electrolyte therein. The cathode electrode (K) is defined to be surrounded by a porous material (16) to convey the electrolyte to the cathode electrode (K) to provide the necessary wetting action with the evaporation through the liquid impermeable, gas permeable membrane (M) for the cell (10). The electrolyte reservoir is spaced below the membrane (M) and is solely conveyed by capillary action to the cathode electrode. A venting element (V) is defined for the cell container (11) to prevent internal pressure variations while preventing loss of electrolyte therethrough.

Abstract: An apparatus and method for polarographically determining the amount of oxygen in a gaseous mixture containing interfering reducible gases such as nitrous oxide is disclosed. The invention has particular application to the determination of oxygen in nitrous oxide containing anesthetic gas mixtures. The oxygen content is determined by operating a special polarographic cell at about -0.6 volts, which is below the voltage at which nitrous oxide would be sensed polarographically. A special cathode is utilized in which the exposed cathode face is disposed near the periphery of a cathode support mounted centrally under the gas permeable membrane so that ion mobility is increased to decrease the internal resistance of the electrochemical cell. It is also found that at the low operating voltage the cathode tends to become passivated or inactive after use. In accordance with the invention the cathode is activated at turn-on by reversing polarity and applying a positive voltage pulse to the cell.