A gas sensor includes a sensor element and a pump cell controller. The pump cell controller performs a normal time control process after a heater control process is started, the normal time control process including a main pump control process, an auxiliary pump control process of controlling an auxiliary pump cell so that a voltage for auxiliary pump reaches a target value, and a normal time measurement pump control process of pumping out oxygen in a measurement chamber by controlling the measurement pump cell so that a measurement voltage reaches a normal time target value. In an early stage of the normal time control process, the pump cell controller performs a correction process of correcting the target value of the voltage for auxiliary pump to a value higher than a target value in a period after the early stage.

A gas sensor includes a sensor element and a pump cell controller. During a normal operation time of the sensor element, the pump cell controller executes a normal time measurement pump control process of pumping out the oxygen in a measurement chamber by controlling a measurement pump cell so that voltage for measurement reaches a normal time target value. At the start-up time of the sensor element, the pump cell controller executes a start-up time measurement pump control process of pumping out the oxygen in the measurement chamber by controlling the measurement pump cell so that the voltage for measurement reaches a start-up time target value higher than the normal time target value. When determining that the oxygen concentration in the measurement chamber is stabilized, the pump cell controller makes switching from the start-up time measurement pump control process to the normal time measurement pump control process.

In a gas sensor configured to measure the concentrations of a plurality of components in the presence of oxygen, in the interior of a structural body made from an oxygen ion conductive solid electrolyte, a preliminary chamber having a mixed potential electrode, an oxygen concentration adjustment chamber having a main pump electrode, and a measurement chamber having a measurement electrode are formed in a manner communicating in this order. While oxygen within the gas to be measured is being discharged by the main pump electrode and the measurement electrode, the NH.sub.3 concentration within the gas to be measured is measured by a mixed potential V0 of the mixed potential electrode.

A gas sensor includes a pump electrode disposed in a measured gas flow path, an oxygen detection electrode disposed in the measured gas flow path and containing platinum and zirconia, and a reference electrode disposed in a reference gas chamber where a reference gas exists, and containing platinum and zirconia. A first position of a front end of the pump electrode is located closer to a rear end side than a second position of a front end of the oxygen detection electrode is. When the content of zirconia in the oxygen detection electrode is X [%], and a ratio of a distance between the first and second positions to a longitudinal dimension of the pump electrode is Y [%], Y≥141.96e.sup.−0.031X is satisfied. The content of zirconia is not lower than that of platinum in the reference electrode.

Apparatus and associated methods relate to a compact gas sensor (CGS) including a housing with a central stepped cavity with one or more first lead contact(s) forming a portion of a base plane in a bottom of the cavity and one or more second lead contact(s) forming a portion of a stepped plane higher than the base plane, the cavity sized to receive a chemically based stack of material made up of a bottom diffusion electrode layer, a middle electrolyte gel layer, and a top diffusion electrode layer. The bottom diffusion electrode layer is in electrical contact with the first lead contact(s). The top diffusion electrode layer electrically couples to the second lead contact(s) via an overlaying micro electromechanical system (MEMS) element layer with conductive coating. In an illustrative example, the CGS may provide gas sensing in small spaces.

A sensor element according to the present invention includes an element body having a measurement-object gas flow section into which an exhaust gas is introduced, an adjustment pump cell including a measurement-object-gas-side electrode disposed in a portion exposed to the exhaust gas on an outer side of the element body, the adjustment pump cell being configured to adjust an oxygen concentration in an oxygen concentration adjustment chamber included in the measurement-object gas flow section, a measurement electrode disposed in a measurement chamber located downstream of the oxygen concentration adjustment chamber, and a reference electrode into which a reference gas is introduced. The measurement-object-gas-side electrode has an Au/(Pt+Au) ratio (=an area of a portion where Au is exposed/an area of a portion where Au and Pt are exposed) 0.2-0.7, the Au/(Pt+Au) ratio being measured by using XPS.

A sensor element for detecting a specific gas concentration in a measurement-object gas includes: an element body including an oxygen-ion-conductive solid electrolyte layer, and having inside a measurement-object gas flow portion that introduces and flows a measurement-object gas and a reference gas chamber used to store a reference gas that is a reference for detecting a specific gas concentration; a reference electrode disposed in the reference gas chamber; and an electrically conductive portion which includes a reference electrode terminal and a reference electrode lead portion that provides electrical continuity between the reference electrode terminal and the reference electrode. The reference gas chamber is provided inside the sensor element in an isolated form, and at least part of the electrically conductive portion is densely formed so as to block movement of oxygen between the reference gas chamber and the outside of the sensor element via the electrically conductive portion.

Electrochemical sensors can include at least two electrodes, over which an electrolyte is formed. The electrodes can be isolated from one another in order for reduction/oxidation reactions to occur at the electrodes and for an electric current to flow therebetween. The present disclosure describes the use of a barrier in the electrochemical sensor that is configured to isolate electrodes from one another for the purpose of preventing electrode shorting. Additionally, the physical structure of the barrier can also act as a stencil for shaping the electrodes.

A sensor element includes a first pump cell including a first pump electrode and a first reference electrode, a first pump circuit including the first pump cell and a first reference electrode lead, a second pump cell including a second pump electrode and a second reference electrode and a second pump circuit including the second pump cell and a second pump electrode. A resistance value R2 of the second pump circuit is higher than a resistance value R1 of the first pump circuit, and a porosity P2 of the second reference electrode lead is higher than a porosity P1 of the first reference electrode lead.

In a sensor element for a limiting-current type gas sensor measuring concentration of NOx in a measurement gas, an inner pump electrode located to face a first internal space communicating with a gas inlet through which the measurement gas is introduced from an external space under predetermined diffusion resistance is made of a cermet of a Pt—Au alloy and zirconia, and the inner pump electrode is located, from among surfaces defining the first internal space, at least on a surface farthest from a heater part in a thickness direction of the element, and is not located on a surface closest to the heater part in the thickness direction.