Abstract: A planar magnetic transducer uses thin film technology to form a coil on a ceramic substrate. A relatively powerful magnet is positioned adjacent the substrate so a changing magnetic reluctance adjacent to the coil can be detected by a voltage change at the coil.

Abstract: An improved sensor having a ceramic element that undergoes a change in an electrical characteristic in response to a change in the partial pressure of oxygen in a mixture of gases to which the ceramic element is exposed. Sensors of this type are used to detect the air/fuel ratio of mixtures supplied to internal combustion engines. Prior art sensors are characterized by little change in their respective electrical characteristics at low operating temperatures. A charge transfer material, platinum or platinum/rhodium is applied to the ceramic element to facilitate or make possible the electron transfers required for sensor operation at low temperatures. Platinum/rhodium alloy is the currently preferred charge transfer material. This alloy, which preferably is 90% platinum and 10% rhodium, reduces the minimum temperature of operation for the sensor as taught herein, and it also substantially eliminates vaporization loss of the charge transfer material.

Abstract: A stoichiometric air/fuel ratio exhaust gas sensor construction particularly useful with variable resistance partial pressure of oxygen responsive sensor material is disclosed. A generally cylindrical mounting body, formed of corrosion resistant material, is arranged for receipt within the exhaust system of an internal combustion engine and is provided with a two-part ceramic insert member for support of a wafer of variable resistance sensor material. The ceramic insert member is comprised of a first portion having a slotted tip for receipt and support of the wafer of partial pressure of oxygen responsive ceramic sensor material. The ceramic insert member is arranged to position the wafer within a perforated shield member at a remote free end of the cylindrical housing body. The wafer includes a pair of extending high temperature resistant electrical conductors which are received within bores provided therefor in the ceramic insert member.

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.