A gas sensor is capable of measuring the concentrations of each of a plurality of target components in a gas being measured. The gas sensor has a sensor element, and one or more processors configured to control an oxygen concentration and to acquire a target component concentration. The oxygen concentration is controlled in a first chamber and a second chamber of a first sensor cell, and the oxygen concentration is also controlled in a second chamber of a second sensor cell. The concentration of a second target component is acquired on the basis of a difference ΔIp between a first pump current value and a second pump current value, and the concentration of a first target component is acquired by subtracting the concentration of the second target component from the second pump current value (total concentration).

A particular-gas concentration-measuring apparatus measures a particular gas concentration being the concentration of a particular gas in a measurement-object gas. The particular-gas concentration-measuring apparatus comprises a particular-gas concentration derivation unit. The particular-gas concentration derivation unit causes an electromotive-force acquisition unit to acquire an electromotive force and derives a correction value compensating for the difference between a correction-value derivation electromotive force that is the electromotive force and the reference electromotive force at a correction-value derivation time. The correction-value derivation time is a time during which a sensing electrode is exposed to a correction-value derivation gas, the correction-value derivation gas being the measurement-object gas where neither ammonia nor a combustible gas is assumed to be included. The particular-gas concentration derivation unit derives the particular gas concentration using a corrected electromotive force determined by correcting the electromotive force with the correction value.

A sensor element includes: a main pump cell constituted by an inner pump electrode facing a first inner space into which a measurement gas is introduced, an external pump electrode provided on a surface of the sensor element, and a solid electrolyte located therebetween; and a measurement pump cell constituted by a measurement electrode facing a second inner space communicated with the first inner space and functioning as a reduction catalyst for NOx; and a solid electrolyte located therebetween. The inner pump electrode is a cermet made of Pt and ZrO.sub.2, the inner pump electrode has a porosity ranging from 1-5% and a thickness ranging from 5-20 μm, a resistance of the main pump cell is equal to or smaller than 150Ω, and a diffusion resistance from the gas inlet to the inner pump electrode is ranging from 200-1000 cm.sup.−1.

A sensor element includes: a first inner space into which a measurement gas is introduced from outside; a second inner space communicated with the first inner space; a main pump cell constituted by an inner pump electrode facing the first inner space, an external pump electrode on a surface of the sensor element, and a solid electrolyte located therebetween; a measurement electrode facing the second inner space and functioning as a reduction catalyst for NOx; and a measurement pump cell constituted by the measurement electrode, the external pump electrode, and a solid electrolyte located therebetween. The inner pump electrode is a cermet made of an AuPt alloy containing Au ranging from 0.6 wt % to 1.4 wt % and ZrO.sub.2, and has a thickness ranging from 5 m to 30 m, a porosity ranging from 5% to 40%, and an area ranging from 5 mm.sup.2 to 20 mm.sup.2.

In a gas sensor having a gas sensor element, a solid electrolyte body has a cylindrical cup shape, one end of which is closed to form a bottom part, and the other end of which is open. The solid electrolyte body has oxygen ion conductivity. A reference electrode is arranged on an interior surface of the solid electrolyte body. An atmosphere is in contact with the reference electrode. The measurement electrode is arranged on an exterior surface of the solid electrode body. Exhaust gas as a detection target is in contact with the measurement electrode. At least one of the measurement electrode and the reference electrode contains thallium particles, within a range of 0.1 ppm and not more than 150 ppm.

A sensor element includes: a main pump cell constituted by an inner pump electrode facing the first inner space into which a measurement gas is introduced, an external pump electrode provided on an element surface, and a solid electrolyte located therebetween; a measurement electrode facing a second inner space communicating with the first inner space and functioning as a reduction catalyst for NOx; and a measurement pump cell constituted by the measurement electrode, the external pump electrode, and a solid electrolyte located therebetween. A diffusion resistance from the gas inlet to the inner pump electrode ranges from 200-1000 cm.sup.1, a resistance of the main pump cell is equal to or smaller than 150, a distance between the electrodes ranges from 0.1-0.6 mm, and the inner pump electrode which is a cermet made of an AuPt alloy and ZrO.sub.2 has an area ranging from 5-20 mm.sup.2.

An air-fuel ratio detection device 1, 1 comprises: a sensor element 2, 2 including a sensor cell 10; a voltage application circuit 40, 40 applying voltage to the sensor cell; a current detector 42, 42 detecting an output current of the sensor cell; an air-fuel ratio calculating part 61 configured to calculate an air-fuel ratio of an exhaust gas; and a parameter detecting part 62 configured to detect or calculate a temperature correlation parameter correlated with a temperature of the sensor element. The air-fuel ratio calculating part is configured to calculate the air-fuel ratio of the exhaust gas based on the temperature correlation parameter and the output current detected when a predetermined voltage is applied to the sensor cell.

A sensor element includes: a main pump cell constituted by an inner pump electrode facing a first inner space into which a measurement gas is introduced, an external pump electrode provided on an element surface, and a solid electrolyte located therebetween; and a measurement pump cell constituted by the measurement electrode facing a second inner space which is communicated with the first inner space and functioning as a reduction catalyst for NOx, and a solid electrolyte located therebetween. The inner pump electrode has a planar shape in which two parts of a front end part relatively having a large area and a rear end part relatively having a small area are sequentially connected in this order from an upstream side in a longitudinal direction of the sensor element while satisfying requirements of a predetermined size and area.

Provided is a gas sensor which is capable of preferably sensing an ammonia gas, and has excellent durability. A mixed-potential gas sensor includes a sensor element composed of an oxygen-ion conductive solid electrolyte, and a heater provided inside the element. The sensor element includes on a surface thereof a sensing electrode formed of a cermet including Pt, Au and an oxygen-ion conductive solid electrolyte, and also includes a reference electrode formed of a cermet of Pt and an oxygen-ion conductive solid electrolyte, and a porous electrode protective layer whose porosity is 5 to 40% covering at least the sensing electrode. The Au abundance ratio in a surface of noble metal particles forming the sensing electrode is 0.4 or more. The concentration of an ammonia gas is determined on the basis of a potential difference occurring between the sensing electrode and the reference electrode when the sensor element is disposed in a measurement gas and heated to 400 C. to 800 C.

The disclosure relates to electrodes and related sensor apparatus for the detection of nitric oxide (NO) and/or peroxynitrite (PON). The electrodes and sensors incorporate electrically conducting boron-doped diamond (BDD) to provide a selective and quantitative detection platform. The sensing electrode for detection of NO includes metallic nanoparticles for oxidation of NO as well as anionic polyelectrolyte layer over the electrically conducting BDD layer. The sensing electrode for detection of PON includes an electrically conductive polymeric layer including a metal-complexed porphyrin for redox reaction with PON over the electrically conducting BDD layer. A corresponding sensor apparatus includes one or two electrochemical cells with associated electrolytes, separate working electrodes for the separate, selective detection of NO or PON, and associated reference electrode(s) and counter electrode(s). Use of the related sensor with various electrochemical techniques to detect NO and/or PON in exhaled breath can be used for detection and/or diagnosis of lung-related conditions.