Abstract: A temperature compensated resistive oxygen sensor and a method of manufacturing the same. On the surface of the sensor there are disposed in spaced relation three electrodes. One electrode and a portion of a second electrode is completely covered by a layer of a resistive material which is sensitive to changes in temperature. Another layer of resistive material which is sensitive to both changes in temperature and changes in the partial pressure of oxygen in the gas to which it is exposed covers the first resistive layer as well as the third electrode and the remaining portion of the second electrode. It is also a feature of the present invention that these layers are applied by shielding part of the surface of the sensor and applying the first layer by a hot thin-layer technique and by removing the shield and applying the second layer also by a hot thin-layer technique.

Abstract: A temperature compensated resistive oxygen sensor and a method of manufacturing the same. On the surface of the sensor there are disposed in spaced relation three electrodes. One electrode and a portion of a second electrode is completely covered by a layer of a resistive material which is sensitive to changes in temperature. Another layer of resistive material which is sensitive to both changes in temperature and changes in the partial pressure of oxygen in the gas to which it is exposed covers the first resistive layer as well as the third electrode and the remaining portion of the second electrode. It is also a feature of the present invention that these layers are applied by shielding part of the surface of the sensor and applying the first layer by a hot thin-layer technique and by removing the shield and applying the second layer also by a hot thin-layer technique.

Abstract: An activated oxygen gas sensor element having an increased voltage output under rich gas conditions, short switching response and reduced internal resistance is produced by chemically treating the inner conductive catalyst electrode of the sensor element with an inorganic acid or acid salt and current activating the outer conductive catalyst electrode by applying a direct current to the sensor element, with the outer electrode as a cathode, while the outer electrode is at an elevated temperature and in the presence of a neutral or inert atmosphere. Air may be used as the atmosphere in contact with the outer electrode during the current activation provided that the sensor is subjected to a subsequent reheating step to provide the desired results.

Abstract: An activated oxygen gas sensor element having an increased voltage output under rich gas conditions, short switching response and reduced internal resistance is produced by chemically treating the inner conductive catalyst electrode of the sensor element with an inorganic acid or acid salt and current activating the outer conductive catalyst electrode by applying a direct current to the sensor element, with the outer electrode as an anode, while the outer electrode is at an elevated temperature and in the presence of a nonoxidizing atmosphere.

Abstract: An oxygen gas sensor having a solid electrolyte oxygen gas sensor element, with an inner conductive catalyst electrode on the interior surface and an outer conductive catalyst electrode on the exterior surface thereof, which has a high voltage output and lower internal resistance is produced by chemically activating said inner conductive catalyst electrode with an inorganic acid or an acid salt. By also subjecting said outer conductive catalyst electrode to a direct current activation under a reducing atmosphere, even more improved properties, such as fast switching response, are achieved.

Abstract: A gas sensor, and its method of manufacture, particularly useful as an exhaust gas sensor for an internal combustion engine air/fuel ratio system, is disclosed. The sensor is comprised of a sintered ceramic body of transition metal oxide, such as titania, and includes a pair of spacedapart electrodes. As the partial pressure of oxygen in the gas being sensed varies in response to variations in the inlet air/fuel mixture ratio, the resistance of the ceramic material varies. The active portion of the sensor body is a substantially uniform body of porous ceramic material having a density of less than about 85% of theoretical density and a modulus of rupture in excess of 11,000 psi. The sensor is fabricated from a very pure transition metal oxide powder having a very fine and highly uniform particle size. The transitional metal oxide is selected so that the operating temperature of the resulting device is less than about 75% and preferably less than about 50% of the melting temperature of the metal oxide.