In a sensor element, a reference gas regulation pump cell pumps in oxygen to the periphery of a reference electrode in which a reference gas is introduced, by the flow of a control current Ip3 between the reference electrode and an outer pump electrode located in a region exposed to a measurement-object gas. An average current density of the reference electrode under the flow of the control current Ip3 is higher than 0 μA/mm.sup.2 and lower than 400 μA/mm.sup.2. The average current density is preferably not higher than 170 μA/mm.sup.2. An average value of the control current Ip3 is preferably higher than 1 μA. The outer pump electrode as a measurement-object gas side electrode of the reference gas regulation pump cell may be provided on an outer surface of a layered body (or more specifically, on a second solid electrolyte layer).

In a sensor element, a reference gas regulation pump cell pumps in oxygen to the periphery of a reference electrode in which a reference gas is introduced, by the flow of a control current Ip3 between the reference electrode and an outer pump electrode located in a region exposed to a measurement-object gas. An average current density of the reference electrode under the flow of the control current Ip3 is higher than 0 μA/mm.sup.2 and lower than 400 μA/mm.sup.2. The average current density is preferably not higher than 170 μA/mm.sup.2. An average value of the control current Ip3 is preferably higher than 1 μA. The outer pump electrode as a measurement-object gas side electrode of the reference gas regulation pump cell may be provided on an outer surface of a layered body (or more specifically, on a second solid electrolyte layer).

Sensor package is provided that includes a package housing defining a receiving cavity and having a package side. The package side includes a detector opening therethrough. The sensor package also includes a sensor module held by the package housing and disposed within the receiving cavity. The sensor module has a sensor side that is aligned with the detector opening such that the sensor side is exposed to a detection space. The sensor module also includes a conductive pathway that is configured to transmit signals that are based on an environmental parameter detected by the sensor module. The sensor package also includes an electrical contact that is coupled to the package housing. The electrical contact includes a contact finger. The contact finger is engaged to the conductive pathway and exerts a normal force against the conductive pathway.

A method and a device are described for detecting at least a portion of a measuring gas component containing bound oxygen in a gas mixture, in particular in an exhaust gas of an internal combustion engine, in a measuring gas chamber by detecting a portion of oxygen that is generated by a reduction of the measuring gas component containing the bound oxygen, in the presence of molecular oxygen, in the device, which includes at least one first pump cell, one reference cell, and one second pump cell. The method includes the following steps: a) generating a first pump current in the first pump cell in such a way that transport of a first portion of oxygen ions takes place between the measuring gas chamber and the surroundings of the device; b) applying a reference pump current to the reference cell in such a way that a second portion of the oxygen ions is transported into a reference gas chamber; c) decomposing the measuring gas component containing the bound oxygen by catalysis at an electrode of the second pump cell, as the result of which additional molecular oxygen is generated from the measuring gas component; d) applying a second pump current to the second pump cell in such a way that a portion of further oxygen ions that are formed from the additional molecular oxygen is transported into the reference gas chamber; and e) holding a sum of currents, formed from the reference pump current and from the second pump current, constant.

A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through a gas inlet; an inner oxygen pump electrode disposed on an inner surface of the measurement-object gas flow part; and a measurement electrode disposed on the inner surface of the measurement-object gas flow part. The inner oxygen pump electrode includes: a region (A) including an electrode end close to the gas inlet, and a region (B) including an electrode end far from the gas inlet. A content rate of an activity reducing metal in a metal material in the region (A) is higher than that in the region (B). A ratio of the length of the region (A) of the inner oxygen pump electrode to the length of the inner oxygen pump electrode is 15% to 90%.

A sensor element includes a base part including a plurality of oxygen-ion-conductive solid electrolyte layers stacked; a measurement-object gas flow part for introduction and flow of a measurement-object gas through one end part in a longitudinal direction of the base part; a main pump cell including an inner main pump electrode disposed on an inner surface of the measurement-object gas flow part, and an outer pump electrode; a target-gas-decomposing pump cell including a target-gas-decomposing pump electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; a residual-oxygen-measuring pump cell including a residual-oxygen-measuring electrode disposed at a position farther from the one end part than the inner main pump electrode, and an outer pump electrode; and a reference electrode. The target-gas-decomposing pump electrode comprises a metal material that has catalytic activity of decomposing a target gas to be measured.

A control method of a gas sensor including a sensor element and an activity determining part includes a temperature raising step of heating the sensor element by a heater of the sensor element to raise a temperature of the sensor element up to an active temperature at which the activity determining part determines that the sensor element is in a measurable active state; a prior driving step of raising the temperature of the sensor element by the heater from the active temperature up to a steady driving temperature, and operating a main pump cell and a measurement pump cell of the sensor element to detect NOx in the measurement-object gas; and a steady driving step of maintaining the temperature of the sensor element by the heater at the steady driving temperature, and operating the main pump cell and the measurement pump cell to continuously detect NOx in the measurement-object gas.

A pair of fuel cells are configured as a hydrogen purity monitor. A first cell, acting as a reference cell, is configured to generate electrical current from the electrochemical reaction of hydrogen and oxidant and has a first fuel inlet configured to receive hydrogen from a first hydrogen source. A second fuel cell, acting as a test cell, is configured to generate electrical current from the electrochemical reaction of hydrogen and oxidant and has a second fuel inlet configured to receive hydrogen from a second hydrogen source. A control system is configured to apply an electrical load to each fuel cell and determine an electrical output of each fuel cell. The control system has a comparator for comparing the electrical outputs of the first and second fuel cells and a purity monitor output configured to give an indication of hydrogen purity based on an output of the comparator.

A pair of fuel cells are configured as a hydrogen purity monitor. A first cell, acting as a reference cell, is configured to generate electrical current from the electrochemical reaction of hydrogen and oxidant and has a first fuel inlet configured to receive hydrogen from a first hydrogen source. A second fuel cell, acting as a test cell, is configured to generate electrical current from the electrochemical reaction of hydrogen and oxidant and has a second fuel inlet configured to receive hydrogen from a second hydrogen source. A control system is configured to apply an electrical load to each fuel cell and determine an electrical output of each fuel cell. The control system has a comparator for comparing the electrical outputs of the first and second fuel cells and a purity monitor output configured to give an indication of hydrogen purity based on an output of the comparator.

A system includes: a NO.sub.x sensor; and a controller configured to: increase an amount of O.sub.2 in a chamber of the NO.sub.x sensor; interpret one or more values of a parameter indicative an amount of O.sub.2 and/or NO.sub.x measured by the NO.sub.x sensor; determine if the one or more values of the parameter exceed a threshold value; and indicate a failure of the NO.sub.x sensor responsive to the one or more values of the parameter do not exceed the threshold value.