Abstract: In one embodiment, a protective coating for an electrode of a sensor is described, the protective coating comprising an annealed catalyst, said annealed catalyst comprising at least one metal that has been subjected to thermal energy that is at least equivalent to or greater than that received from calcining the at least one metal for 24 hours at a temperature of 930 degrees C in air. In another embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to or less than that received from calcining the at least one metal for 24 hours at 1030 degrees C in air. In one exemplary embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to that received from calcining the at least one metal for 24 hours at 980 degrees C in air.

Abstract: One embodiment of an ammonia gas sensor includes: a reference electrode, an ammonia selective sensing electrode and an electrolyte disposed therebetween. The sensing electrode comprises the reaction product of a main material selected from the group consisting of vanadium, tungsten, molybdenum, vanadium oxides, tungsten oxides, molybdenum oxides, and combinations comprising at least one of the foregoing main materials, and an electrically conducting material selected from the group consisting of electrically conductive metals, electrically conductive metal oxides, and combinations comprising at least one of the foregoing.

Abstract: Disclosed herein is an ammonia sensor element comprising an ammonia selective sensor electrode, a reference electrode, a solid electrolyte in ionic communication with the ammonia selective sensor electrode and the reference electrode, and a protective layer disposed on the ammonia selective sensor electrode, comprising a porous portion comprising an ammonia-inert material. A method of making an ammonia gas sensor element comprises disposing an ammonia selective sensor electrode on and in ionic communication with a solid electrolyte, disposing a reference electrode on and in ionic communication with the solid electrolyte, and disposing a protective layer comprising a porous portion comprising an ammonia-inert material on the ammonia selective sensor electrode.

Abstract: Disclosed herein is a method of making a gas sensor element, comprising calcining a NOx sensor electrode material at a NOx sensor electrode material calcination temperature of about 1200 to about 1600° C. to form a calcined NOx sensor electrode material, disposing the calcined NOx sensor electrode material on a substrate to form a substrate comprising a NOx sensor electrode, and firing the substrate comprising the NOx sensor electrode at a gas sensor element firing temperature to form a gas sensor element comprising a NOx sensor electrode. Also disclosed is a gas sensor comprising the gas sensor element.

Abstract: In one embodiment, a protective coating for an electrode of a sensor is described, the protective coating comprising an annealed catalyst, said annealed catalyst comprising at least one metal that has been subjected to thermal energy that is at least equivalent to or greater than that received from calcining the at least one metal for 24 hours at a temperature of 930 degrees C. in air. In another embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to or less than that received from calcining the at least one metal for 24 hours at 1030 degrees C. in air. In one exemplary embodiment, the annealed catalyst will comprise at least one metal that has been subjected to thermal energy that is equal to that received from calcining the at least one metal for 24 hours at 980 degrees C. in air.

Abstract: One embodiment of an ammonia gas sensor includes: a reference electrode, an ammonia selective sensing electrode and an electrolyte disposed therebetween. The sensing electrode comprises the reaction product of a main material selected from the group consisting of vanadium, tungsten, molybdenum, vanadium oxides, tungsten oxides, molybdenum oxides, and combinations comprising at least one of the foregoing main materials, and an electrically conducting material selected from the group consisting of electrically conductive metals, electrically conductive metal oxides, and combinations comprising at least one of the foregoing.

Abstract: A sensor element can comprise a co-fired heater section, a sensing section, and a third insulating layer disposed between the electrode portion and the temperature sensor. The heater section can comprise a heater, a shield, and a temperature sensor, with a first insulating layer disposed between the heater and the shield, and a second insulating layer disposed between the shield and the temperature sensor. The sensing section can comprise an electrode portion and a sensing portion, wherein the sensing portion is disposed on a side of the electrode portion opposite the heater section.

Abstract: A method of treating a gas sensor comprising: disposing the gas sensor in a basic agent solution comprising a basic agent selected from the group consisting of Group IA of the Periodic Table of Elements, Group IIA of the Periodic Table of Elements, and combinations comprising at least one of the foregoing metals, wherein the gas sensor comprises an electrolyte disposed between and in ionic communication with a first electrode and a second electrode; disposing the gas sensor in an acidic agent solution; wetting at least a portion of a porous protective layer of the gas sensor with an alkaline-carbonate solution; and heating the gas sensor.

Abstract: One embodiment of an ammonia gas sensor includes: a reference electrode, an ammonia selective sensing electrode and an electrolyte disposed therebetween. The sensing electrode comprises the reaction product of a main material selected from the group consisting of vanadium, tungsten, molybdenum, vanadium oxides, tungsten oxides, molybdenum oxides, and combinations comprising at least one of the foregoing main materials, and an electrically conducting material selected from the group consisting of electrically conductive metals, electrically conductive metal oxides, and combinations comprising at least one of the foregoing.

Abstract: A gas sensor is created comprising an electrochemical cell having a solid electrolyte layer disposed between an exhaust gas electrode and a reference electrode. A resistor is disposed in electrical communication with a heater and the reference electrode. The resistor can be disposed on a side of the gas sensor; on a side of the gas sensor such that the resistor is electrically connected through a via hole; over at least a portion of at least two sides of the gas sensor; or disposed in a void extending at least from the heater to the pump electrode, such that the void extends to at least a surface of the gas sensor, extends to at least partially through the gas sensor, or extends completely through the gas sensor. A method for using this gas sensor comprises applying a voltage to the heater within the gas sensor. A current is directed through the resistor to the reference electrode to pump oxygen into the reference electrode.

Abstract: A method of treating a gas sensor comprising: disposing the gas sensor in a basic agent solution comprising a basic agent selected from the group consisting of Group IA of the Periodic Table of Elements, Group IIA of the Periodic Table of Elements, and combinations comprising at least one of the foregoing metals, wherein the gas sensor comprises an electrolyte disposed between and in ionic communication with a first electrode and a second electrode; disposing the gas sensor in an acidic agent solution; wetting at least a portion of a porous protective layer of the gas sensor with an alkaline-carbonate solution; and heating the gas sensor.

Abstract: A gas sensor comprises: an electrochemical cell comprising an electrolyte disposed in ionic communication with a sensing electrode and a reference electrode, wherein the reference electrode comprises an inhibitor that reduces a first catalytic activity with selected sensing gas constituents without substantially affecting a second catalytic activity with oxygen; a heater disposed in thermal communication with the electrochemical cell; and at least one insulating layer disposed in contact with the heater. Methods for making and using the gas sensor with a selective reference electrode comprising an inhibitor are also disclosed.

Abstract: The invention includes the use of a pre-equilibration zone on an exhaust gas sensor to provide catalytic site to catalyze non-reacted components of the exhaust gas prior to the gas sample reaching the sensor's outer electrode. The pre-equilibration zone preferably includes a precious metal on the surface of a porous carrier. The invention also includes a method of making an exhaust sensor including a pre-equilibration zone, and a method of sampling an exhaust gas by passing the same through a pre-equilibration zone.

Abstract: Generally, the instant invention includes a method of using a sensor having an outer electrode including a gold-containing layer to diagnose the efficiency and useful life of a catalytic converter. The sensor having a gold-containing layer is positioned in an exhaust gas, combustion engine downstream from both the engine and the catalytic converter used to clean the exhaust. The sensor produces an voltage output responsive to the combustibles concentration in the exhaust gas. The voltage output from the sensor is measured and compared to a predetermined threshold correlated to a desirable combustibles concentrations in the exhaust stream or to a threshold output indicative of an inefficiently operating catalytic converter. An electrical output is then provided which is responsive to the comparison. The electrical output may be an indicator light, gauge or other devices for instructing the operator of a vehicle that the catalytic converter requires maintenance.