Abstract: A gas sensor element of the present invention detects concentration of a specific gas within a measured gas. The gas sensor element comprises: a wiring layer formed inside a sensor; an insulating layer covering a front surface of the wiring layer; an electrode terminal provided on a main surface of the insulating layer on an opposite side of the insulating layer from the wiring layer, and electrically connected to the wiring layer; and an intermediate layer interposed between the electrode terminal and the wiring layer, and electrically connecting the electrode terminal and the wiring layer. The electrode terminal is composed of a first metal material. The wiring layer is composed of a second metal material. The intermediate layer is composed of whichever of the first metal material and the second metal material has the lower melting point.

Abstract: A sensor device for sensing a gas includes a sensing region, and a readout region that is electrically and mechanically connected to the sensing region by way of a connecting web. The readout region, the sensing region, and the connecting web are formed from a substrate, and are isolated from the substrate by a clearance cutout. The sensing region has an ion-conducting region configured to provide a measuring signal dependent on the gas. The readout region (is configured to read out the measuring signal.

Abstract: A sensor is provided, which may include: a sensor layer containing a sensor material, wherein an electrical resistance of the sensor material changes upon adsorption of an adsorbate at the sensor material; a circuit electrically coupled to the sensor layer and configured to apply an electrical current to the sensor layer that heats the sensor layer.

Abstract: A sensor element of a gas sensor for determining gas components in gas mixtures includes a field effect transistor and/or a diode which has a current flow which changes upon contact with a gas to be detected, and which is positioned in a manner protected, by a protective cap, from direct access by the gas mixture. The protective cap has a heating element, a glass former, and/or an oxidation catalyst.

Abstract: A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas.

Abstract: A gas sensor including a reduction section (18) for reducing NO2 contained in exhaust gas to NO. The reduction section (18) is provided on the upstream side of a first diffusion resistor section (103) which limits the flow of the exhaust gas into a first measurement chamber (101). When NOX passes through the first diffusion resistor section (103), NO2 which has a greater molecular weight than NO has a lower degree of diffusion. Since NO2 is reduced to NO at the reduction section (18), the exhaust gas passing through the first diffusion resistor section (103) hardly contains NO2. Therefore, the speed of flow of NOX through the first diffusion resistor section (103) is not limited by NO2, whereby sensitivity for detection of NOX can be improved.

Abstract: An automatic sensor excitation voltage adjustment feature, a multi-range concentration feature, a single calibration feature and a barrier circuit feature. The automatic sensor excitation voltage adjustment feature includes a transmitter having a transmitter microprocessor that provides an initial voltage to a sensor having a sensor microprocessor. As the voltage changes a correction signal is relayed from the sensor microprocessor to the transmitter microprocessor. The correction signal is used to adjust the voltage applied to the sensor. The multi-range concentration sensor feature includes an amplifier associated with the sensor/microprocessor to create gain settings used to optimize sensor resolution by changing a gain value for the sensor. This enables use of a single sensor for a variety of different concentration ranges.

Abstract: A corrosion sensor includes a plurality of metal strips having different thicknesses. A first metal strip with the least thickness is first employed to provide sensitive corrosion detection. After an exposed portion of the first metal strip is consumed, a second metal strip having a second least thickness can be employed to provide continued sensitive corrosion detection employing a remaining un-corroded portion of the second metal strip. The plurality of metal strips can be sequentially employed as exposed portions of thinner metal strips become unusable through complete corrosion and un-corroded exposed portions of thicker metal strips become thin enough to provide sensitive corrosion detection.

Abstract: A gas sensor (200) includes a gas sensor element (10) extending in an axial direction (O), having a detection portion (11) provided at a front end thereof, and having electrode pads (12a) provided at a rear end thereof; connection terminals (31, 32) electrically connected to the respective electrode pads; and a cover (60, 61) covering the rear end of the gas sensor element and the connection terminals. The cover integrally has a connector portion (63) having an opening (63b) which allows an external connector to be inserted thereinto and removed therefrom in a predetermined direction, and has a connector terminal member (120) which can be inserted into the opening. The connector terminal member has a plurality of connector terminals (70) to be electrically connected to the respective connection terminals, and an insulator (121) integrally molded with the connector terminals. Also disclosed is a method for manufacturing the gas sensor.

Abstract: A gas sensing device that includes differential temperature compensation.

Abstract: A sensor device containing a gas sensor is exposed to a gas. The gas sensor emits a voltage based on a property of the gas. The voltage output by the gas sensor is received by an integrated circuit (“IC”). The IC may convert the voltage to a digital representation of the voltage. The IC may determine a property of the gas based on the voltage. The digital representation of the voltage or a representation of the property of the gas is then transmitted as data via an audio jack of the sensor device. A computer device receives the data via an audio jack. Using one or more processors, the computer device analyzes the data and generates a recommendation. The recommendation and the property of the gas may be displayed.

Abstract: A method of sensing gases during medical procedures that includes electronically altering a gas-identification sensor, coupled with an electronic medical device, to selectively detect at least one of a plurality of gases, receiving the at least one of the plurality of gases in the electronic medical device, the electronic medical device having an energy output, transferring the at least one of the plurality of gases to the gas-identification sensor for identification, and then reducing an amount of energy emitted from the energy output upon identification of the at least one of the plurality of gases.

Abstract: A substance detection sensor includes an insulating layer; two electrodes spaced in opposed relation to each other on the insulating layer; and conductive layers formed between the two electrodes on the insulating layer so as to electrically connect the two electrodes, and of which a swelling ratio varies depending on the type and/or amount of a specific gas. The conductive layers are formed by dividing into plural layers between the two electrodes.

Abstract: A gas sensor having high detection sensitivity and a low output signal noise includes a laminate of thermistor ceramic, a catalytic electrode, an internal electrode, and external electrodes. When coming into contact with a detection target gas, the catalytic electrode generates heat, and the resistance of a thermistor layer of a sensing portion is decreased. Since the heat generated by the catalytic electrode is directly transferred to the thermistor layer without passing through an insulating layer or the like, high detection sensitivity is obtained. In addition, the structure can be formed in which heat of the sensing portion is insulated by a hollow portion and heat diffusion is prevented, so that the heat capacity of the sensing portion is further decreased.

Abstract: A discharge ionization current detector using a low-frequency barrier discharge is provided to improve the linearity of detection sensitivity with respect to a sample introduction amount. From a lower end of a lower gas passage connected to a lower end of an upper gas passage, a dilution gas is supplied upward against a downward flow of a plasma gas. A gas discharge passage for discharging a plasma gas, the dilution gas and a sample gas is arranged between an ion-collecting electrode and a bias voltage application electrode. The sample gas introduced through a capillary tube is mixed with the plasma gas and the dilution gas due to a disturbed flow generated by collision of the plasma gas and the dilution gas. The sample component is efficiently ionized by light from the plasma without undergoing light-shielding effect of concentrated sample components.

Abstract: A gas detection system is provided. The system includes a sample gas inlet configured to receive a sample of gas and a sample chamber operably coupled to the sample gas inlet. The sample chamber has at least one gas sensor disposed therein. The gas sensor provides a gas sensor output indicative of a species of interest in the sample of gas. A controller is coupled to the at least one gas sensor and is configured to provide information related to the species of interest based on the gas sensor output. A moisture removal device is disposed to receive the sample of gas and remove moisture from the sample before the sample reaches the at least one gas sensor.

Abstract: The present invention provides a hybrid nanomaterial electrode, comprising a pair of spaced-apart electrodes, at least three pairs of metallic nanowires disposed between the electrodes and respectively connected with the electrodes, and at least a detecting material connecting with the metallic nanowires. The detecting material is formed as a semiconductor nanostructure or a conductor nanostructure. The hybrid nanomaterial electrode of the present invention can be used in a gas detector for detecting volatile organic compounds, and has the advantage of providing high sensitivity, low detection limit, and the ability to operate at room temperature.

Abstract: Embodiments of the present invention provide improved systems and methods for providing an atomic sensor device. In one embodiment, the device comprises a sensor body, the sensor body enclosing an atomic sensor, wherein the sensor body contains a gas evacuation site located on the sensor body, the gas evacuation site configured to connect to a gas evacuation device. The device also comprises a getter container coupled to an opening in the sensor body, an opening in the getter container coupled to an opening in the sensor body, such that gas within the sensor body can freely enter the getter container. The device further comprises an evaporable getter enclosed within the getter container, the evaporable getter facing away from the sensor body.

Abstract: This invention describes a sample collection method that could release and collect residues of explosives and other chemicals from a surface; the described method is implemented into a compact detection system that can be used as a “wand” for screening chemicals residues on human body. The wand configuration includes multiple functionalities for contrabands detection. The invention further describes a desorption method that can control chemical fragmentation pathway during desorption. The invention describes a combined detection device that detects trace chemicals and metal at the same time.

Abstract: A device for detecting volatile substances has a containment box with at least one inlet opening for introduction of gas flow, one or more outlet openings of the gas flow, at least one analysis opening, one or more detection sensors arranged in the containment box, and at least one probe insertable in the containment box through at least one analysis opening. When the probe is initially treated by a sample of a substance to be examined and is inserted in the containment box, the gas flow uniformly carries the volatile substances from the sample to one or more sensors. A detection apparatus and a detection method for volatile substances are also described.

Abstract: The invention provides a liquid cell for an atomic force microscope. The liquid cell includes a liquid cell housing with an internal cavity to contain a fluid, a plurality of conductive feedthroughs traversing the liquid cell housing between the internal cavity and a dry side of the liquid cell, a cantilevered probe coupled to the liquid cell housing, and a piezoelectric drive element disposed on the cantilevered probe. The cantilevered probe is actuated when a drive voltage is applied to the piezoelectric drive element through at least one of the conductive feedthroughs. A method of imaging an object in a liquid medium and a method of sensing a target species with the liquid cell are also disclosed.

Abstract: A gas sensor is disclosed. The gas sensor includes a gas sensing layer, at least one electrode, an adhesion layer, and a response modification layer adjacent to said gas sensing layer and said layer of adhesion. A system having an exhaust system and a gas sensor is also disclosed. A method of fabricating the gas sensor is also disclosed.

Abstract: The invention provides a light weight analyzer, e.g., detector, capable of locating clandestine graves. The detector utilizes the very specific and unique chemicals identified in the database of human decompositional odor. This detector, based on specific chemical compounds found relevant to human decomposition, is the next step forward in clandestine grave detection and will take the guess-work out of current methods using canines and ground-penetrating radar, which have historically been unreliable. The detector is self contained, portable and built for field use. Both visual and auditory cues are provided to the operator.

Abstract: A particulate monitoring system includes a conduit in which to a pass a fluid sample from an input port to an output port. The particulate monitoring system receives a fluid sample inputted to the conduit through the input port. The fluid sample can include different sizes of particulate matter. The particulate monitoring system controls a flow of the fluid sample through the conduit to age the particulate matter. Gravitational forces cause a portion of the particulate matter in the fluid sample to fall into a basin as opposed to being exhausted through the output port, which is disposed at a vertically higher level of the conduit than the input port. Thus, the particulate monitoring system outputs a portion of the original particulate matter in the fluid sample (e.g., particulate matter that does not drop into the basin out due to gravity) for analysis.

Abstract: A flue gas sensor of a combustion device is disclosed. The flue gas sensor may include a housing and a gas detector disposed within the housing, wherein the gas detector detects or measures at least one gas in a flue gas stream of the combustion device. The housing may also include a water barrier member through which the at least one gas comes into contact with the gas detector.

Abstract: A sensor senses a magnitude of a physical parameter of the sensor's environment. The sensor has first and second electrodes, and a material layer between them. The material has an electrical property, e.g., capacitance or resistance, whose value depends on the magnitude of the physical parameter. The first electrode is formed in a first layer, and the second electrode is formed in a second layer, different from the first layer. The first layer has a trench and an elevation next to the trench. The trench has a bottom wall and a side wall. The material is positioned on the bottom wall and on the side wall and on top of the elevation. The trench accommodates at least a part of the second electrode. The second electrode leaves exposed the material formed on top of the elevation.

Abstract: Examples described herein illustrate techniques related to satellite aerosol generation. In some examples, aerosols are sensed based on the interaction between satellite aerosols and a corona discharge from a corona source.

Abstract: A gas sensor detects carbon dioxide, for example for use in air-conditioning systems. The gas sensor is based on a field effect transistor construction. It has a polymer-based material sensitive to carbon dioxide as gas-sensitive layer. The material has a cross-sensitivity with respect to air humidity. The influence of humidity is compensated for by using the signal of a humidity sensor.

Abstract: To provide a gas sensor which can stably carry out a securement of an electric continuity between a sensor element and a contact member. A contact member in which an electric connection to a sensor element is obtained by pinching and fixing the sensor element in an inserting port formed by a pair of housing members includes a constraint member which is provided in an outer periphery of a pair of housing members. The constraint member constrains a displacement of a pair of housing members within a predetermined range before the sensor element is pinched and fixed by a pair of housing members, and exists in a state of being pinched between the annular member and a pair of housing member without generating any reaction force with respect to the external force, after the sensor element is pinched and fixed.

Abstract: The sensor element, which can detect the concentration of a specified gas, is held with a housing with a front end thereof exposed. A protective cover includes an inner cover and an outer cover, and secured to the housing. A ratio ?1/?2 is set to a range from 0.6 to 0.9, where ?1 represents an outer diameter of a portion where an inner gas aperture is formed in the inner cover, and ?2 represents an inner diameter of a portion where an outer gas aperture is formed in the outer cover.

Abstract: A gas sensor including a metal shell; a detection element main body held by the metal shell; a porous protection layer coated on a leading end portion of the detection element main body; and a protector including a side wall surrounding an element protruding portion of the detection element main body protruding from a leading end of the metal shell. The side wall has introduction holes formed therein which allow gas to be introduced. The porous protection layer includes a first portion; and a second portion provided on a base end side with respect to the first portion and having a progressively reduced thickness in a direction toward a leading end of the detection element. The second portion is disposed closer to the base end of the detection element than the introduction holes in the axial direction.

Abstract: A detection and identification system includes a sensor unit (100) having a sensor array that detects and identifies at least one chemical included in an air flow. The system also includes a pump (120) that drives the air flow through the detection and identification system, in which the pump receives the air flow that has passed out of the sensor unit. The system further includes an adsorption unit (130) that dries and cleans the air flow within the detection and identification system, to obtain a substantially dry and clean air flow, in which the adsorption unit receives the air flow that has passed out of the pump. The system also includes at least one valve (140) that receives the substantially dry and clean air flow that has passed through the adsorption unit. The valve provides the substantially dry and clean air flow to the sensor unit in a close-loop circulation operation to thereby clean a sensor array.

Abstract: A gas and/or humidity sensor system may include two differing capacitive sensor unit cell structures. A first unit cell has a capacitance measurement that is dependent upon capacitance effects that substantially do not extend to the upper reaches of the sensor's gas/humidity sensitive layer and a second unit cell has a capacitance measurement that is dependent upon electric field effects that extend substantially beyond the distance of the electric fields of the first unit cell. The capacitance associated with the electric fields in the upper regions of the gas/humidity sensitive layer may then be obtained to a first order by subtracting the capacitance of the first unit cell from the capacitance of the second unit cell. By subtracting the capacitance, a capacitance associated with the capacitance of the electric fields of the layer (or portion of layer) of interest may be approximated.

Abstract: A gas-measuring probe for determining a physical characteristic of a measuring gas, in particular the concentration of a gas component or the temperature or pressure of the measuring gas, which includes a sensor element accommodated in a housing, at least one connection cable for the sensor element having an electrical conductor, which is enclosed by an insulation sheath and contacts the sensor element, and a cable channel sealing the housing end, which has at least one axial cable feedthrough through which the connection cable is guided out of the housing. To achieve long-lasting sealing at the cable-exit end of the housing even at higher temperatures, the insulation sheath of the connection cable is at least regionally welded to the cable wall of the cable feedthrough. To this end, a tube made of a material that fuses with the insulation sheath and the cable channel when heated is slipped over the cable section of the connection cable lying inside the cable channel.

Abstract: Micro-electromechanical device for measuring the viscosity of a fluid, comprises a measuring chamber with a micromechanical actuator, arranged as a cantilever above a metallically conductive counter electrode, elastically deformable towards the counter electrode, surrounded by the fluid to be measured and made of a metallically conductive material, a two-terminal RF voltage source that can be switched off, having a first output terminal connected to the actuator, and a second output terminal connected to the counter electrode, and which is designed to output an RF voltage signal that is suitable for deflecting the actuator out of its rest position, and a measuring device to detect a change in the frequency, amplitude or phase of the RF signal in order to determine a measurement value for the viscosity-dependent speed at which the actuator is deformed.

Abstract: A method for geochemical gradient exploration includes the steps of: densely collecting soil samples and gas samples along a longitudinal direction in a certain depth range of a superficial layer; collecting soil samples and gas samples in the range from 1 meter to 50 meters deep by a special drilling machine; after analyzing and processing the geochemical indicators, extracting and figuring the bathymetric curve and the curve of gradients, the section curve and section curve of gradient along a certain direction, contour section of various indicators and contour section of various indicator gradients, so as to process the data and to represent the figure in 3D. More information, especially the variation information along the longitudinal direction, can be obtained. Gradient prospecting is realized by collecting samples along the depth direction and by analyzing variations in geochemical indicators along the depth.

Abstract: The present invention relates to a device for analysing the internal atmosphere of the casing of an electric rotating machine comprising a housing with an atmosphere inlet opening, a suction pump for drawing the atmosphere within the casing of the electric machine, a pump inlet conduit for placing the atmosphere inlet opening in fluid communication with the suction pump, an atmosphere inlet conduit adapted to place the interior of the casing in fluid communication with the atmosphere inlet opening, transducer means adapted to measure the percentage volume of at least one explosive compound present in the atmosphere drawn by the pump and adapted to generate an electric signal proportional to the percentage volume of the explosive compound. The device also comprises comparison means adapted to compare the percentage volume of at least one explosive compound with a predetermined threshold value of percentage volume.

Abstract: An apparatus is disclosed for facilitating spoilage detection in bulk grain storage bins via dust-free or substantially dust-free air sampling. Dust particles are passively removed from sampled air without the use of barrier filters or electrostatic screens, but instead through the use of a non-linear pathway that is open at one end and closed at the other end. A system is disclosed that incorporates a coiled pathway as an air inlet element combined with a carbon dioxide or other gas detector element to provide an integrated detector module suitable for permanent installation in a dusty bulk grain storage bin environment to provide spoilage gas measurements over time. The system may communicate data to a central data storage system via cellular telephone or long range radio frequency data transmission. Alerts and alarms are generated and transmitted electronically to users via email, SMS text, automated phone messages and other means.

Abstract: A gas concentration meter includes a meter body having a control circuit and a gas concentration sensor accommodated therein and electrically connected together said control circuit board and a gas passage extending through the gas concentrations sensor, and a fan unit mounted at one side of the meter body and having a fan blade rotatably mounted inside an annular peripheral wall thereof. The gas passage has its one end terminating in an inlet and extends to an inner side of the annular peripheral wall. When a gas flow goes through the fan unit to rotate the fan blade, a part of the gas flow will enter the inlet of the gas passage, enhancing measuring accuracy and shortening the reaction time of the gas concentration sensor. Further, a wind speed sensor may be provided to measure flow velocity.

Abstract: An apparatus for measuring a concentration of CO2 for a vehicle may include an indoor panel of a vehicle in which an air inlet is mounted, and a CO2 sensing unit mounted in the indoor panel, including a light emitting unit, a light receiving unit, and a case surrounding the light emitting unit and the light receiving unit so as to reflect and move light on a plane, and vertically introduced with air introduced into the inlet with respect to the plane on which light moves.

Abstract: The gas sensor includes a sensor element, a first insulator inside which the sensor element is inserted, a second insulator disposed on a proximal side of the first insulator so as to cover a proximal side of the sensor element, and a contact member held by the second insulator and sandwiching the sensor element. A proximal end portion of the first insulator and a distal end portion of the second insulator abut on each other in an axial direction. Each the proximal end portion and the distal end portion is provided with a positioning structure. The positioning structure is configured to restrict a relative movement between the first and second insulators in a sandwiching direction in which the sensor element is sandwiched by the contact member and in an orthogonal direction perpendicular to the sandwiching direction and in the axial direction.

Abstract: In a gas sensor (100), a base end portion (175b) of a second outer wall (175) of an outer protector (171) is airtightly connected to a forward end portion (164c) of a first inner wall (164) of an inner protector (161). The outer protector (171) has a taper wall (172) which is located on the axially forward end side of the second outer wall (175). The taper wall (172) has the shape of a tapered tube whose diameter decreases toward the axially forward end side, and has a second outer hole (176), which is a forward end opening. The entire taper wall (172) is disposed on the axially forward end side in relation to the inner bottom wall (162) of the inner protector (161).

Abstract: A sensor device for an oxygen module mountable on board an aircraft includes an electrical conducting element, a defining device for defining at least one measurement section, assigned to the oxygen module, on the electrical conducting element, and an evaluating unit for determining an electrical resistance present along the at least one measurement section, the evaluating unit further being configured to ascertain, based on the determined electrical resistance, whether the oxygen module is present. An aircraft has at least one oxygen module mounted on board the aircraft and at least one sensor device of the above type.

Abstract: A sensor element for detecting a parameter of a gas mixture in a gas chamber, having a first electrode and a first diffusion barrier layer arranged to be coupled to said first electrode in a predetermined first region, and arranged such that the gas mixture of the gas chamber only impinges on the first electrode in the first region via the first diffusion barrier layer. In addition, the sensor element has a second electrode arranged such that the gas mixture of the gas chamber impinges on the second electrode in a further first region. The sensor element includes a solid electrolyte designed to be coupled to the first and the second electrodes.

Abstract: A gas sensor is provided. The gas sensor includes a gas-sensitive layer which changes in its characteristic properties upon contact with a detectable gas. The gas-sensitive layer has as the main sensitive part, a polycrystalline layer composed of a large number of uniform nano-size microcrystal grains which join together in the planar direction.

Abstract: Exemplary embodiments provide a self-powered wireless gas sensor system and a method for gas sensing using the system. The system can be used to detect and constantly track a presence of various gases including hydrogen, ozone and/or any hydrocarbon gas, and remotely transmit the sensing signal. The system can include a low power gas sensor that consumes less than about 30 nano-watts of power. As a result, the system can detect the presence of hydrogen at about 10 ppm. The sensor can also provide a fast response time of about 1-2 seconds. In various embodiments, the system can be physically small and packaged with all components assembled as a single compact unit.

Abstract: A method for determining the quantity of outgassing of a fuel from a lubricant located in an intake section housing of an internal combustion engine may include (a) setting a first coil current through the housing, (b) measuring a first output value of a lambda controller, (c) setting a second coil current through the housing, the second coil current having a different current strength than the first coil current, (d) measuring a second output value of the lambda controller and (e) determining the quantity of outgassing of the fuel based on the measured first and second output values. In addition, a method for adapting a lambda value for a fuel/air mixture to be burnt in an internal combustion engine during a lower load range may include the above-mentioned method of determining the quantity of outgassing of a fuel.

Abstract: Embodiments of the present disclosure provide for methods of selecting a nanostructured deposit for a conductometric gas sensor, methods of detecting a gas based on the acidic or basic characteristic of the gas using a conductometric gas sensor, devices including conductometric gas sensors, arrays of conductometric gas sensors, methods of determining the acidic or basic characteristic of a gas, methods of treating a sensor, and the like.

Abstract: A gas sensor includes an inner electrode formed on an inner surface of a base body. The inner electrode has an inner sensing portion formed in a gas contact inner region such that the inner sensing portion is located on the whole of a heat-facing area of the gas contact inner region facing a heating portion in a radial direction of the base body, a terminal contact portion formed in a rear end region such that the terminal contact portion is located in at least a part of the rear end region in a circumferential direction of the base body and a lead portion formed only on a part of the inner surface of the base body in the circumferential direction of the base body so as to connect the inner sensing portion and the terminal contact portion to each other.

Abstract: A gas sensor, including a cylindrical outer tube; and a seal member disposed therein, the seal member including: a lead wire insert hole and an atmosphere communication hole. The seal member has a groove extending outwards in a radial direction at a rear end-facing surface from the atmosphere communication hole while circumventing the lead wire insert hole, the groove having a cutout toward the front end of the seal member. The gas sensor further includes: a protection portion which covers the atmosphere communication hole; and an arm couples the protection portion and the outer tube, and extends in the radial direction, the arm being at least partially disposed in the groove of the seal member. and the arm is disposed so as to define a gap with the bottom surface of the groove.