Abstract: An electrochemical NO2 sensor includes a reference electrode, a sensing electrode having a sensing electrode material, and an electrolyte. The electrolyte is disposed between and in ionic communication with the sensing electrode and the reference electrode to form an NO2 sensing cell. The NO2 sensing cell produces an electromotive force when exposed to NO2. The sensing electrode material comprises a compound consisting essentially of Si and oxygen and expressed by ABD. Oxygen is element D, Si is element B, and element A includes one or more elements selected from the group consisting of Mn, Co, and Fe.

Abstract: A sensor system includes a common gas chamber and a reference gas chamber respectively configured to receive an exhaust gas and a reference gas. A Nernst cell is exposed to the common gas chamber and the reference air chamber. The Nernst cell provides a reference signal indicative of an oxygen difference between the common gas chamber and the reference air chamber. An oxygen electrochemical pump cell is exposed to the common gas chamber and exhaust gas and provides an oxygen signal indicative of an oxygen only concentration. A NOx electrochemical cell is exposed to the common gas chamber and provides a NOx signal indicative of a NOx concentration. A processor is in communication with the Nernst cell, the oxygen-only electrochemical pump cell and NOx electrochemical cells. The processor outputs oxygen and NOx signals and provide a NOx concentration and oxygen concentration of the exhaust.

Abstract: A NO2 gas sensing element includes an electrolyte, a reference electrode in contact with the electrolyte, and a sensing electrode selective to NO2 in contact with the electrolyte spaced apart from the reference electrode. The NO2 selective sensing electrode includes an oxide material comprising: (1) a mixed oxide according to the formula (Mn2-u-v-wCovMgwSiO4-u)+?(Mn3Al2Si3O12)+?(SiO2), wherein 0?(u+v+w)?2.0, 0???0.5, and 0???0.1; (2) a mixed oxide according to the formula (Mn2-x-y-zCoyMgzSiO4-x)+?(ZnO)+?(SiO2), wherein 0?(u+v+w)?2.0, 0???0.5, and 0???0.1; or combinations of mixed oxides (1) and (2).

Abstract: A sensor system includes a common gas chamber and a reference gas chamber respectively configured to receive an exhaust gas and a reference gas. A Nernst cell is exposed to the common gas chamber and the reference air chamber. The Nernst cell provides a reference signal indicative of an oxygen difference between the common gas chamber and the reference air chamber. An oxygen electrochemical pump cell is exposed to the common gas chamber and exhaust gas and provides an oxygen signal indicative of an oxygen only concentration. A NOx electrochemical cell is exposed to the common gas chamber and provides a NOx signal indicative of a NOx concentration. A processor is in communication with the Nernst cell, the oxygen-only electrochemical pump cell and NOx electrochemical cells. The processor outputs oxygen and NOx signals and provide a NOx concentration and oxygen concentration of the exhaust.

Abstract: A sensor system includes a common gas chamber and a reference gas chamber that respectively receive an exhaust gas and a reference gas. A Nernst cell is exposed to the common gas chamber and the reference air chamber and provides a reference signal indicative of an oxygen difference between the common gas chamber and the reference gas chamber. An oxygen electrochemical pump cell is exposed to the common gas chamber to provide an oxygen signal indicative of an oxygen-only concentration. A gas electrochemical cell is exposed to the common gas chamber and the reference gas chamber and provides a gas signal indicative of a gas concentration. A processor includes a pulsation module that provides a positive and a negative excitation voltage to the gas electrochemical cell for a duration and that are each followed by a decay curve indicative of the gas concentration.

Abstract: An electrochemical NO2 sensor includes a reference electrode, a sensing electrode having a sensing electrode material, and an electrolyte. The electrolyte is disposed between and in ionic communication with the sensing electrode and the reference electrode to form an NO2 sensing cell. The NO2 sensing cell produces an electromotive force when exposed to NO2. The sensing electrode material comprises a compound consisting essentially of Si and oxygen and expressed by ABD. Oxygen is element D, Si is element B, and element A includes one or more elements selected from the group consisting of Mn, Co, and Fe.

Abstract: An electrochemical detection system for determining a concentration of a gas in exhaust gases of a combustion process. The system includes an electrolyte, a reference electrode, and a sense electrode that cooperate to form an electrochemical sensor that exposes both the reference electrode and the sense electrode to the exhaust gases. The electrochemical sensor is configured to output a sensor signal indicative of a species concentration of a species gas in the exhaust gases. The sensor signal exhibits a transient error in response to a change in a reference concentration of a reference gas in the exhaust gases. The processor is configured to determine the species concentration based on the sensor signal, and to determine an estimate of the transient error based on an operating condition of the combustion process.

Abstract: An electrochemical detection system for determining a concentration of a gas in exhaust gases of a combustion process. The system includes an electrolyte, a reference electrode, and a sense electrode that cooperate to form an electrochemical sensor that exposes both the reference electrode and the sense electrode to the exhaust gases. The electrochemical sensor is configured to output a sensor signal indicative of a species concentration of a species gas in the exhaust gases. The sensor signal exhibits a transient error in response to a change in a reference concentration of a reference gas in the exhaust gases. The processor is configured to determine the species concentration based on the sensor signal, and to determine an estimate of the transient error based on an operating condition of the combustion process.

Abstract: A NO2 gas sensing element includes an electrolyte, a reference electrode in contact with the electrolyte, and a sensing electrode selective to NO2 in contact with the electrolyte spaced apart from the reference electrode. The NO2 selective sensing electrode includes an oxide material comprising: (1) a mixed oxide according to the formula (Mn2-u-v-wCovMgwSiO4-u)+?(Mn3Al2Si3O12)+?(SiO2), wherein 0?(u+v+w)?2.0, 0???0.5, and 0???0.1; (2) a mixed oxide according to the formula (Mn2-x-y-zCoyMgzSiO4-x)+?(ZnO)+?(SiO2), wherein 0?(u+v+w)?2.0, 0???0.5, and 0???0.1; or combinations of mixed oxides (1) and (2).

Abstract: An NO2 sensor comprises a sensing electrode material that includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; and oxygen. In an alternate embodiment, the sensing electrode material includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; an element selected from the group consisting of Mg, Al, Li, Na, and K; and oxygen. Sensors made with these sensing electrode materials demonstrate good NO2 sensitivity and reduced sensitivity to cross-interference from NO and NH3.

Abstract: A gas sensor includes a metallic shell extending along a shell axis and defining a shell attaching surface that is substantially perpendicular to the shell axis; a metallic shield extending along a shield axis and defining a shield attaching surface that is substantially perpendicular to the shield axis; and a ceramic sensing element extending along a sensing element axis, the sensing element being rigidly fixed at a first axial location of the sensing element to the shell and the sensing element being laterally supported by the shield at a second axial location of the sensing element that is axially spaced apart from the first axial location. The shield is attached to the shell at an interface formed between the shield attaching surface and the shell attaching surface, thereby accommodating misalignment between the shield axis and the shell axis. A method of making the gas sensor is also provided.

Abstract: An electrochemical detection system for determining a concentration of a gas in exhaust gases of a combustion process. The system includes an electrolyte, a reference electrode, and a sense electrode that cooperate to form an electrochemical sensor that exposes both the reference electrode and the sense electrode to the exhaust gases. The electrochemical sensor is configured to output a sensor signal indicative of a species concentration of a species gas in the exhaust gases. The sensor signal exhibits a transient error in response to a change in a reference concentration of a reference gas in the exhaust gases. The processor is configured to determine the species concentration based on the sensor signal, and to determine an estimate of the transient error based on an operating condition of the combustion process.

Abstract: An NO2 sensor comprises a sensing electrode material that includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; and oxygen. In an alternate embodiment, the sensing electrode material includes a compound consisting essentially of one or more elements selected from the group consisting of Mn, Co, and Fe; an element selected from the group consisting of Si and Ti; an element selected from the group consisting of Mg, Al, Li, Na, and K; and oxygen. Sensors made with these sensing electrode materials demonstrate good NO2 sensitivity and reduced sensitivity to cross-interference from NO and NH3.

Abstract: A gas sensor includes a metallic shell extending along a shell axis and defining a shell attaching surface that is substantially perpendicular to the shell axis; a metallic shield extending along a shield axis and defining a shield attaching surface that is substantially perpendicular to the shield axis; and a ceramic sensing element extending along a sensing element axis, the sensing element being rigidly fixed at a first axial location of the sensing element to the shell and the sensing element being laterally supported by the shield at a second axial location of the sensing element that is axially spaced apart from the first axial location. The shield is attached to the shell at an interface formed between the shield attaching surface and the shell attaching surface, thereby accommodating misalignment between the shield axis and the shell axis. A method of making the gas sensor is also provided.

Abstract: A method for fault identification of gas sensors exposed to a gas mixture is disclosed for gas sensors having an output that depends on concentrations of two gas species in the gas mixture. The method includes receiving output signals from two such sensors, processing the output signals in a controller that implements a model of the sensors so as to identify a fault in the first gas sensor or the second gas sensor; and providing an indication of any identified faults.

Abstract: An electrochemical detection system for determining a concentration of a gas in exhaust gases of a combustion process. The system includes an electrolyte, a reference electrode, and a sense electrode that cooperate to form an electrochemical sensor that exposes both the reference electrode and the sense electrode to the exhaust gases. The electrochemical sensor is configured to output a sensor signal indicative of a species concentration of a species gas in the exhaust gases. The sensor signal exhibits a transient error in response to a change in a reference concentration of a reference gas in the exhaust gases. The processor is configured to determine the species concentration based on the sensor signal, and to determine an estimate of the transient error based on an operating condition of the combustion process.

Abstract: A method and device allow the determination of the concentrations of a plurality of gas species in a gas mixture based on the output signals from a plurality of gas sensors, each of which is sensitive to a plurality of gas species in the gas mixture. The method includes measuring the response of each sensor at a number of levels of each gas in the mixture, determining a mathematical representation of the response characteristics of each sensor, and using the mathematical representation to determine gas concentrations from sensor readings.

Abstract: A method for fault identification of gas sensors exposed to a gas mixture is disclosed for gas sensors having an output that depends on concentrations of two gas species in the gas mixture. The method includes receiving output signals from two such sensors, processing the output signals in a controller that implements a model of the sensors so as to identify a fault in the first gas sensor or the second gas sensor; and providing an indication of any identified faults.

Abstract: A method and device allow the determination of the concentrations of a plurality of gas species in a gas mixture based on the output signals from a plurality of gas sensors, each of which is sensitive to a plurality of gas species in the gas mixture. The method includes measuring the response of each sensor at a number of levels of each gas in the mixture, determining a mathematical representation of the response characteristics of each sensor, and using the mathematical representation to determine gas concentrations from sensor readings.