The teachings of present disclosure may be embodied in gas sensors for detecting oxygen and methods for detecting oxygen in a gas mixture. For example, a gas sensor for detecting oxygen in a gas mixture may include: an oxygen ion conductor; at least two electrodes arranged on the oxygen ion conductor, the at least two of the electrodes arranged to come into contact with the gas mixture during operation of the gas sensor; a control device applying a polarization voltage or a polarization current to the at least two electrodes during a polarization period; a measuring device for measuring the current or the voltage at the at least two electrodes; and an evaluation device for calculating the oxygen content from the measured voltage or the measured current. Calculating the oxygen content may be based on: a current measured during the polarization period, or a charge which has flowed over the polarization period, or a voltage measured directly after the polarization period.

A gas concentration detection apparatus is provided with a measuring gas chamber, a solid electrolyte body, a pump cell, a sensor cell, a pump cell controller and a sensor cell detection section. The pump cell controller applies an elimination voltage to the pump cell at a start-up point, before a gas concentration is detected. The water in the measuring gas chamber is decomposed and hydrogen is generated by application of the elimination voltage. Oxygen occluded in a sensor electrode of the sensor cell is removed by the hydrogen.

A method of operating a sensor to detect an analyte in an environment, wherein the sensor includes a working electrode and circuitry in operative connection with the working electrode, includes performing a sensor interrogation cycle including applying electrical energy to the working electrode to generate a non-faradaic current, measuring a response to the generation of the non-faradaic current to determine a state of the sensor, and actively controlling the circuitry to dissipate the non-faradaic current.

A sensor element includes a layered body that includes a measurement-object gas flowing portion which a measurement object gas is introduced and flowed in and a reference electrode that is formed inside of the layered body and a reference gas introducing layer made of a porous material that introduces a reference gas being used as a standard for detection of a specific gas concentration in the measurement-object gas and that flows the reference gas to the reference electrode, the reference gas introducing layer including an inlet portion serving as an inlet of the reference gas and one or more gas flowing spaces provided over a region from the inlet portion to the reference electrode in a direction in which the reference gas is flowed.

An SCU as a control device for the gas sensor (first and second NOx sensors) includes an applied voltage switching unit for switching an applied voltage of a pump cell when a deterioration detecting function is performed, and a deterioration rate calculation unit for calculating a deterioration rate of a sensor cell based on a slope during a transient change in an output of the sensor cell according to a switching of the applied voltage by the applied voltage switching unit.

A gas sensor for detecting one or more contaminants in a refrigerant includes a housing having disposed therein a membrane electrode assembly comprising a sensing electrode, a counter electrode, and a solid polymer electrolyte disposed between the sensing electrode and the counter electrode. The sensing electrode comprises nanoparticles of a first catalyst comprising noble metal. The counter electrode comprises nanoparticles of a second catalyst comprising noble metal. The sensing electrode in the sensor has been preconditioned by exposure under a positive voltage bias to a preconditioning gas comprising the contaminant(s) or their precursors or derivatives.

A hydrogen detector for gas and fluid media is disclosed. The detector includes a selective membrane and a housing. Within the housing is a potential measuring unit and a ceramic sensing element made of a solid electrolyte. A standard electrode is located within a cavity of the ceramic sensing element and a porous platinum electrode is applied to an external layer of the ceramic sensing element. A potential measuring unit passes through a sealed lead-in at the upper end of the housing and is brought out to the standard electrode. The selective membrane, which is attached to a hole in the end of the lower bushing, is closed with a plug. The cavity limited by the inner surface of the lower bushing, the external part of the bottom of the ceramic sensing element and the inner surfaces of the selective membrane and the plug is leak-tight.

A hydrogen detector for a gaseous medium is disclosed. The detector includes an operating element fixed to the upper part of the detector housing by means of sealant. The lower part of the detector is insulated and in contact with a heater that provides operational temperature of the medium supplied to a waterproof membrane of a steam hydrogen compartment. Disturbances introduced by a measurement flow is transferred to the central core of a potential measuring unit through a measuring platinum electrode fixed to the lower part of a ceramic sensing element connected to the metal casing of the sensing element by the sealant. A standard electrode is located in the inner cavity of the ceramic sensing element. The external part of the ceramic sensing element bottom is covered with a porous platinum electrode. The end of the potential measuring unit central core is brought out to the standard electrode.

The present invention relates to a graphene-based or other 2-D material membrane which allows the passage of protons and deuterons and to a method of facilitating proton or deuteron permeation through such a membrane. Monocrystalline membranes made from mono- and few-layers of graphene, hBN, molybdenum disulfide (MoS2), and tungsten disulfide (WS2) etc. are disclosed. In effect, the protons or deuterons are charge carriers that pass through the graphene or other 2-D material membrane. This process can be contrasted with the passage of gaseous hydrogen. Hydrogen is an uncharged gaseous species which is diatomic. In other words, the gas is in molecular form when considering the normal barrier properties whereas in the case of the present invention, the species which is being transported through the membrane is a charged ion comprising a single atom. Membranes of the invention find use in a number of applications such as fuel cells.

In a gas sensor where an exhaust gas is introduced into a chamber provided in a gas sensor element so that an oxygen concentration is reduced in a pump cell on the upstream side to detect NO.sub.x in the exhaust gas in a sensor cell on the downstream side, the surface of at least one of a solid electrolyte sheet and a shielding sheet that constitute wall surfaces of the chamber has a warped shape which is convex inwardly of the chamber at a position where the pump cell is formed. The warp amount is in the range from 0.10% or higher to 1.38% or lower, and the height in the stacking direction of the diffusion layer is lower than the average height Have in the stacking direction of the chamber at the position where the pump cell is formed.