Gas sensor

Abstract

A gas sensor is provided. The gas sensor (100) includes a substrate (10), a first conductor (20) and a second conductor (25) disposed on the substrate (10), an insulating layer (40), and an adsorbent material layer (30). The insulating layer (40) covers the first conductor (20) and the second conductor (25) and has a first opening portion (45) that exposes a portion of a surface of the first conductor (20) and a second opening portion (46) that exposes a portion of a surface of the second conductor (25). The adsorbent material layer (30) includes a conductive material and an organic adsorbent material capable of adsorbing a gas and is in contact with the first conductor (20) and the second conductor (25) through the first opening portion (45) and the second opening portion (46), respectively.

Description

[0001] This application is a divisional application of application No. 201880023318.8 entitled "Gas Sensor" filed with the China National Intellectual Property Administration on March 28, 2018. Technical Field

[0002] This disclosure relates to gas sensors. Background Technology

[0003] Gas sensors are known as devices for detecting gases. Gas sensors can easily detect gases.

[0004] like Figure 11 As shown, Patent Document 1 describes a substance detection sensor 300 for detecting gases. The substance detection sensor 300 includes a conductive layer 330, a first electrode 320, and a second electrode 325. The conductive layer 330 covers both the first electrode 320 and the second electrode 325.

[0005] By using the material detection sensor 300, gas can be detected as follows. If gas comes into contact with the conductive layer 330, the conductive layer 330 swells. This causes a change in the resistance of the conductive layer 330. The gas can be detected by measuring the change in the resistance of the conductive layer 330.

[0006] Prior art literature

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2008 / 084582 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] According to the substance detection sensor 300 described in Patent Document 1, it is sometimes impossible to detect the gas sufficiently when the gas concentration is low.

[0011] The purpose of this disclosure is to provide a technique for more reliable gas detection.

[0012] Technical solutions for solving the problem

[0013] That is, this disclosure provides a gas sensor that includes:

[0014] substrate;

[0015] A first conductor and a second conductor are disposed on the substrate;

[0016] An insulating layer covers the first conductor and the second conductor, and the insulating layer has a first opening and a second opening, the first opening exposing a portion of the surface of the first conductor, and the second opening exposing a portion of the surface of the second conductor; and

[0017] The adsorption material layer includes a conductive material and an organic adsorption material capable of adsorbing gases, and is in contact with the first conductor and the second conductor respectively through the first opening and the second opening.

[0018] Invention Effects

[0019] The gas sensor disclosed herein enables more reliable gas detection. Attached Figure Description

[0020] Figure 1 This is a top view of the gas sensor according to Embodiment 1 of this disclosure.

[0021] Figure 2 It is along Figure 1 The gas sensor shown is a cross-sectional view along line II-II.

[0022] Figure 3 It is used to explain in Figure 1 The diagram shows the positions of multiple first openings and multiple second openings in the gas sensor.

[0023] Figure 4 This is a top view of a gas sensor assembly according to one embodiment of this disclosure.

[0024] Figure 5 This is a top view of a gas sensor according to a variation of Embodiment 1 of this disclosure.

[0025] Figure 6 It is along Figure 5 The gas sensor shown is a cross-sectional view along line VI-VI.

[0026] Figure 7 This is a top view of the gas sensor involved in Embodiment 2.

[0027] Figure 8 This is a top view of the gas sensor involved in Embodiment 3.

[0028] Figure 9 This is a graph showing the rate of change of resistance of the adsorbent material layer for each of samples 1 to 5.

[0029] Figure 10 This is a graph showing the rate of change of resistance of the adsorbent material layer for samples 2, 6, and 7.

[0030] Figure 11 This is a top view of a traditional gas sensor. Detailed Implementation

[0031] The gas sensor involved in the first aspect of this disclosure has the following features:

[0032] substrate;

[0033] A first conductor and a second conductor are disposed on the substrate;

[0034] An insulating layer covering the first conductor and the second conductor, the insulating layer having a first opening and a second opening, the first opening exposing a portion of the surface of the first conductor, and the second opening exposing a portion of the surface of the second conductor; and

[0035] The adsorption material layer includes a conductive material and an organic adsorption material capable of adsorbing gases, and is in contact with the first conductor and the second conductor respectively through the first opening and the second opening.

[0036] According to the first method, when the organic adsorbent adsorbs a gas, the volume of the adsorbent layer changes. Specifically, the adsorbent layer expands or contracts. This change in volume alters the positional relationships between the conductive materials within the adsorbent layer, thus changing the path of the current within it. In the gas sensor, current does not flow from the surface of the first conductor covered by the insulating layer to the adsorbent layer. Nor does current flow from the surface of the second conductor covered by the insulating layer to the adsorbent layer. That is, the number of current paths within the adsorbent layer is relatively small. Therefore, the change in current path caused by the change in the positional relationships between the conductive materials is significant. If the change in current path is significant, the resistance of the adsorbent layer changes significantly. Because the resistance of the adsorbent layer changes significantly, gas detection can be performed more reliably.

[0037] In a second aspect of this disclosure, for example, in the gas sensor according to the first aspect, the insulating layer has a plurality of first openings and a plurality of second openings. According to the second aspect, changes in the resistance of the adsorbent material layer caused by changes in the path of the current can be stably detected. Therefore, gas can be detected stably.

[0038] In the third aspect of this disclosure, for example, in the gas sensor involved in the second aspect, a plurality of the first openings are arranged in an arc shape, and a plurality of the second openings are arranged in an arc shape. According to the third aspect, changes in the resistance of the adsorbent material layer caused by changes in the path of the current can be stably detected. Therefore, gas can be detected stably.

[0039] In the fourth aspect of this disclosure, for example, in the gas sensor according to the third aspect, the adsorbent material layer has a circular or annular shape when viewed from above. When viewed from above, a plurality of first openings are located on a virtual circle concentric with a virtual circle defined by the outer periphery of the adsorbent material layer, and a plurality of second openings are located on a virtual circle concentric with the virtual circle defined by the outer periphery of the adsorbent material layer. According to the fourth aspect, when the adsorbent material layer adsorbs gas, the adsorbent material layer expands or contracts in the radial direction of the virtual circle defined by the outer periphery of the adsorbent material layer. The plurality of first openings are located on a virtual circle concentric with the virtual circle defined by the outer periphery of the adsorbent material layer. Furthermore, the plurality of second openings are located on a virtual circle concentric with the virtual circle defined by the outer periphery of the adsorbent material layer. Therefore, when the adsorbent material layer expands or contracts, deviations in the current path are suppressed. Thus, changes in the resistance of the adsorbent material layer caused by changes in the current path can be stably detected. Therefore, gas can be stably detected.

[0040] In the fifth aspect of this disclosure, for example, in the gas sensor involved in the fourth aspect, one first opening selected from a plurality of first openings and one second opening selected from a plurality of second openings are located on one of a plurality of virtual straight lines that extend radially from the center of the virtual circle defined by the outer periphery of the adsorbent material layer. According to the fifth aspect, gas can be detected more stably.

[0041] In the sixth aspect of this disclosure, for example, in the gas sensor involved in the second aspect, a plurality of first openings are arranged in a straight line, and a plurality of second openings are arranged in a straight line. According to the sixth aspect, changes in the resistance of the adsorbent material layer caused by changes in the path of the current can be stably detected. Therefore, gas can be detected stably.

[0042] In the seventh aspect of this disclosure, for example, in the gas sensor according to the sixth aspect, the adsorbent material layer has a rectangular shape when viewed from above. When viewed from above, a plurality of first openings are arranged along a direction extending from at least one of a plurality of contour lines constituting the outer periphery of the adsorbent material layer, and a plurality of second openings are arranged along the direction in which the plurality of first openings are arranged. According to the seventh aspect, when the adsorbent material layer adsorbs gas, the adsorbent material layer expands or contracts in the directions extending from the plurality of contour lines constituting the outer periphery of the adsorbent material layer. The plurality of first openings are arranged along a direction extending from at least one of the plurality of contour lines constituting the outer periphery of the adsorbent material layer. Furthermore, the plurality of second openings are arranged along the direction in which the plurality of first openings are arranged. Therefore, when the adsorbent material layer expands or contracts, deviations in the current path are suppressed. Thus, changes in the resistance of the adsorbent material layer caused by changes in the current path can be stably detected. Therefore, gas can be detected stably.

[0043] In the eighth aspect of this disclosure, for example, in the gas sensor involved in any of the first to seventh aspects, the entire first opening overlaps with the first conductor when viewed from above, and the entire second opening overlaps with the second conductor when viewed from above. According to the eighth aspect, changes in the resistance of the adsorbent material layer accompanying changes in the current path can be stably detected. Therefore, gas can be detected stably.

[0044] In the ninth aspect of this disclosure, for example, in the gas sensor involved in any of the first to eighth aspects, the organic adsorbent material comprises at least one selected from the group consisting of polyalkylene glycols, polyesters, silicones, glycerols, nitriles, dicarboxylic acid monoesters, and aliphatic amines. According to the ninth aspect, the organic adsorbent material can readily adsorb gases.

[0045] In the tenth aspect of this disclosure, for example, in the gas sensor involved in any of the first to ninth aspects, the conductive material includes carbon black. According to the tenth aspect, when the volume of the organic adsorbent material changes, the resistance of the adsorbent material layer changes more significantly. Therefore, gas can be detected more reliably.

[0046] In the eleventh aspect of this disclosure, for example, in the gas sensor according to the tenth aspect, the weight ratio of the carbon black to the weight of the adsorbent material layer is in the range of 0.25 to 0.95. According to the eleventh aspect, current can easily flow from the first conductor or the second conductor to the adsorbent material layer. Therefore, the resistance of the adsorbent material layer can be easily measured.

[0047] In the twelfth aspect of this disclosure, for example, in the gas sensor involved in any of the first to eleventh aspects, the areas of the first opening and the second opening, viewed from above, are respectively between 0.2 and 2000 μm. 2 The range is defined in the twelfth method. Because the number of current paths in the adsorbent material layer is sufficiently small, the resistance of the adsorbent material layer changes more significantly due to variations in the current paths. Therefore, gas detection is more reliable. Furthermore, current easily flows from the first or second conductor to the adsorbent material layer. Therefore, the resistance of the adsorbent material layer can be easily measured.

[0048] In the thirteenth aspect of this disclosure, for example, in the gas sensor involved in any of the first to twelfth aspects, the first opening and the second opening are respectively circular in plan view, and the diameters of the first opening and the second opening are respectively in the range of 0.5 to 50 μm. According to the thirteenth aspect, the number of current paths in the adsorbent material layer is sufficiently small, and the resistance of the adsorbent material layer changes more significantly due to the change in the current path. Therefore, gas can be detected more reliably. Furthermore, current can easily flow from the first conductor or the second conductor to the adsorbent material layer. Therefore, the resistance of the adsorbent material layer can be easily measured.

[0049] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The present disclosure is not limited to the following embodiments.

[0050] (Implementation Method 1)

[0051] like Figure 1 as well as Figure 2 As shown, the gas sensor 100 according to Embodiment 1 includes a substrate 10, a first conductor 20, a second conductor 25, an insulating layer 40, and an adsorption material layer 30. The substrate 10 is, for example, plate-shaped. The substrate 10 has, for example, a rectangular or circular shape when viewed from above. In this embodiment, the substrate 10 has a circular shape when viewed from above. The first conductor 20 and the second conductor 25 function as electrodes, respectively.

[0052] A first conductor 20 is disposed on a substrate 10. The lower surface of the first conductor 20 is in contact with the upper surface of the substrate 10. The shape of the first conductor 20 is not particularly limited. The first conductor 20 may have an arc or ring shape when viewed from above. In this embodiment, the first conductor 20 has an arc shape when viewed from above and also has a strip shape. The center of the virtual circle defined by the outer peripheral surface of the first conductor 20 may or may not coincide with the centroid of the surface of the substrate 10 (the center of the upper surface of the substrate 10). The ratio of the distance from the centroid of the surface of the substrate 10 to the first conductor 20 to the radius of the surface of the substrate 10 may be in the range of 0.1 to 0.8.

[0053] The first conductor 20 includes an exposed portion 20a that protrudes to the outside of the gas sensor 100. Figure 1 In the original design, the exposed portion 20a extends beyond the outer periphery of the substrate 10 and outwards from the substrate 10. However, the first conductor 20 may not have a portion extending beyond the outer periphery of the substrate 10 and outwards from the substrate 10. For example, an opening may be provided in the substrate 10, through which a portion of the lower surface of the first conductor 20 is exposed to the outside of the gas sensor 100. In this case, a portion of the lower surface of the first conductor 20 corresponds to the exposed portion 20a.

[0054] The second conductor 25 is disposed on the substrate 10. The lower surface of the second conductor 25 is in contact with the upper surface of the substrate 10. The shape of the second conductor 25 is not particularly limited. The second conductor 25 may, for example, surround the first conductor 20. That is, the second conductor 25 may also be located further outward than the first conductor 20 in the radial direction of the surface of the substrate 10. The second conductor 25 is not in contact with the first conductor 20. The second conductor 25 may, for example, have an arc or ring shape when viewed from above. In this embodiment, the second conductor 25 has an arc shape when viewed from above and also has a strip shape. The center of the virtual circle defined by the outer peripheral surface of the second conductor 25 may or may not coincide with the center of gravity of the surface of the substrate 10. The center of the virtual circle defined by the outer peripheral surface of the second conductor 25 may or may not coincide with the center of the virtual circle defined by the outer peripheral surface of the first conductor 20. In this embodiment, the first conductor 20 and the second conductor 25 are disposed in a concentric circle shape. The ratio of the distance from the centroid of the surface of the substrate 10 to the second conductor 25 to the radius of the surface of the substrate 10 can be in the range of 0.2 to 0.9.

[0055] The second conductor 25 includes an exposed portion 25a that protrudes from the outside of the gas sensor 100. Figure 1In the original design, the exposed portion 25a extends beyond the outer periphery of the substrate 10 and outwards from the substrate 10. However, the second conductor 25 may not have a portion extending beyond the outer periphery of the substrate 10 and outwards from the substrate 10. For example, an opening may be provided in the substrate 10, so that a portion of the lower surface of the second conductor 25 is exposed to the outside of the gas sensor 100. In this case, a portion of the lower surface of the second conductor 25 corresponds to the exposed portion 25a.

[0056] The insulating layer 40 covers both the first conductor 20 and the second conductor 25. The insulating layer 40 is in contact with both the first conductor 20 and the second conductor 25. The insulating layer 40 may cover the entire upper surface of the substrate 10, or it may partially cover the upper surface of the substrate 10.

[0057] The insulating layer 40 has a first opening 45 and a second opening 46. The first opening 45 exposes a portion of the surface of the first conductor 20. The first opening 45 overlaps with the upper surface of the first conductor 20. For example, the entire first opening 45 overlaps with the first conductor 20 in a top view. The first opening 45 penetrates the insulating layer 40 in the thickness direction. Except for the first opening 45, the insulating layer 40 covers the entire upper surface and the entire side surface of the first conductor 20.

[0058] The insulating layer 40 may have a plurality of first openings 45. The number of the plurality of first openings 45 is not particularly limited. The number of the plurality of first openings 45 may be in the range of 1 to 20, 2 to 8, 2 to 4, or 2 to 3. In this embodiment, the insulating layer 40 has a plurality of first openings 45a, 45b, 45c, and 45d. The plurality of first openings 45a, 45b, 45c, and 45d are arranged in an arc shape. In other words, the plurality of first openings 45a, 45b, 45c, and 45d are arranged along the length direction of the first conductor 20. More specifically, the plurality of first openings 45a, 45b, 45c, and 45d are arranged along the circumference of the first conductor 20. In this embodiment, the plurality of first openings 45a, 45b, 45c, and 45d are arranged at equal intervals along the circumference of the first conductor 20.

[0059] The second opening 46 exposes a portion of the surface of the second conductor 25. The second opening 46 overlaps with the upper surface of the second conductor 25. For example, the entire second opening 46 overlaps with the second conductor 25 in a top view. The second opening 46 penetrates the insulating layer 40 in the thickness direction. Except for the second opening 46, the insulating layer 40 covers the entire upper surface and the entire side surface of the second conductor 25.

[0060] The insulating layer 40 may have a plurality of second openings 46. The number of the plurality of second openings 46 is not particularly limited. The number of the plurality of second openings 46 may range from 1 to 20, from 2 to 8, from 2 to 4, or from 2 to 3. The number of the plurality of second openings 46 may be the same as or different from the number of the plurality of first openings 45. In this embodiment, the insulating layer 40 has a plurality of second openings 46a, 46b, 46c, and 46d. The plurality of second openings 46a, 46b, 46c, and 46d are arranged in an arc shape. In other words, the plurality of second openings 46a, 46b, 46c, and 46d are arranged along the length direction of the second conductor 25. More specifically, the plurality of second openings 46a, 46b, 46c, and 46d are arranged along the circumference of the second conductor 25. In this embodiment, the plurality of second openings 46a, 46b, 46c, and 46d are arranged at equal intervals along the circumference of the second conductor 25.

[0061] The shapes of the first opening 45 and the second opening 46 are not particularly limited. For example, the first opening 45 and the second opening 46 may have circular or rectangular shapes when viewed from above. The areas of the first opening 45 and the second opening 46 when viewed from above can be between 0.2 and 200,000 μm. 2 The range can be from 0.2 to 2000 μm. 2 The range can also be between 15 and 25 μm. 2 The resistance of the adsorbent material layer 30 changes more significantly due to the small number of current paths in the adsorbent material layer 30. Therefore, gas can be detected more reliably. Furthermore, current easily flows from the first conductor 20 or the second conductor 25 to the adsorbent material layer 30. Therefore, the resistance of the adsorbent material layer 30 can be easily measured. When the first opening 45 and the second opening 46 are circular in plan view, their diameters can be in the ranges of 0.5–500 μm, 0.5–50 μm, and 4.37–5.64 μm, respectively. The area and diameter of the first opening 45 and the second opening 46 in plan view can be measured by observing the surface of the insulating layer 40 with an electron microscope.

[0062] The adsorbent material layer 30 contacts the first conductor 20 and the second conductor 25 through the first opening 45 and the second opening 46, respectively. For example, Figure 1 as well as Figure 2As shown, the adsorbent material layer 30 is in contact with the first conductor 20 through the first opening 45c. The adsorbent material layer 30 is in contact with the second conductor 25 through the second opening 46c. Therefore, when a voltage is applied to the first conductor 20 and the second conductor 25, current flows to the adsorbent material layer 30. Thus, the resistance of the adsorbent material layer 30 can be measured. The adsorbent material layer 30 is disposed on the insulating layer 40. The adsorbent material layer 30 covers the entire upper surface and the entire side surface of the insulating layer 40. The adsorbent material layer 30 may also only partially cover the upper surface and the side surface of the insulating layer 40. The adsorbent material layer 30 may cover the entire upper surface of the substrate 10 or only partially cover the upper surface of the substrate 10. The adsorbent material layer 30 may or may not be in contact with the substrate 10.

[0063] The thickness of the adsorbent layer 30 is determined based on the type of gas to be detected and the composition of the adsorbent layer 30. The thinner the adsorbent layer 30, the more stably its resistance can be measured. The thickness of the adsorbent layer 30 can be in the range of 0.1 to 10 μm. The shape of the adsorbent layer 30 is not particularly limited. For example, the adsorbent layer 30 may have a circular or annular shape when viewed from above. In this embodiment, the adsorbent layer 30 has an annular shape when viewed from above. The area of ​​the adsorbent layer 30 when viewed from above is, for example, between 0.002 and 50 mm². 2 The range.

[0064] like Figure 3 As shown, in this embodiment, when viewed from above, the plurality of first openings 45a, 45b, 45c, and 45d are located on a virtual circle C2 that is concentric with a virtual circle C1 defined by the outer periphery 30a of the adsorbent material layer 30. Furthermore, in Figure 3 For convenience, the first conductor 20 and the second conductor 25 are omitted. Multiple first openings 45a, 45b, 45c, and 45d are arranged at equal angular intervals along the virtual circle C2.

[0065] In this embodiment, when viewed from above, the multiple second openings 46a, 46b, 46c, and 46d are located on a virtual circle C3 that is concentric with the virtual circle C1. The virtual circle C3 is different from the virtual circle C2. The multiple second openings 46a, 46b, 46c, and 46d are arranged at equal angular intervals along the virtual circle C3.

[0066] In this embodiment, a plurality of first openings 45a and 45c and a plurality of second openings 46a and 46c are located on a virtual straight line L1. A plurality of first openings 45b and 45d and a plurality of second openings 46b and 46d are located on a virtual straight line L2. Virtual straight lines L1 and L2 extend radially from the center O of the virtual circle C1, respectively. Virtual straight lines L1 and L2 are orthogonal.

[0067] like Figure 1 As shown, the gas sensor 100 may also include a first wall portion 11. The first wall portion 11 surrounds the surface of the substrate 10. The first wall portion 11 has a ring shape when viewed from above. The first wall portion 11 extends upward from the substrate 10 (in the thickness direction of the substrate 10). The surface of the substrate 10 surrounded by the first wall portion 11 has, for example, a circular shape. The first wall portion 11 is connected to the outer periphery of the substrate 10. The first wall portion 11 can be integrated with the substrate 10. In other words, the first wall portion 11 can be part of the substrate 10. The first wall portion 11 extends upward beyond the adsorbent material layer 30. The inner peripheral surface of the first wall portion 11 is in contact with the adsorbent material layer 30.

[0068] The gas sensor 100 may also include a second wall portion 12. The second wall portion 12 extends upward from a portion of the surface of the substrate 10. The shape of the second wall portion 12 is, for example, cylindrical or cylindrical. The second wall portion 12 is connected to a portion of the surface of the substrate 10. The second wall portion 12 can be integrated with the substrate 10. In other words, the second wall portion 12 can be part of the substrate 10. The second wall portion 12 is surrounded by a first conductor 20. The outer peripheral surface of the second wall portion 12 surrounds the center of gravity of the surface of the substrate 10. The second wall portion 12 extends upward beyond the adsorbent material layer 30. The outer peripheral surface of the second wall portion 12 is in contact with the adsorbent material layer 30. The adsorbent material layer 30 is disposed between the first wall portion 11 and the second wall portion 12.

[0069] The material of the substrate 10 is not particularly limited as long as it can maintain the shape of the gas sensor 100. The substrate 10 can be, for example, a Si substrate, a metal plate, a glass plate, or a polymer film.

[0070] The materials of the first conductor 20 and the second conductor 25 are not particularly limited, as long as they are materials capable of applying voltage. For example, the first conductor 20 and the second conductor 25 each comprise at least one metal selected from the group consisting of silver, gold, copper, platinum, and aluminum. The material of the first conductor 20 can be the same as the material of the second conductor 25.

[0071] The material of the insulating layer 40 is not particularly limited as long as it is insulating. The material of the insulating layer 40 may include at least one selected from the group consisting of insulating polymers, ceramics, and glass. Insulating polymers may include at least one selected from the group consisting of polyethylene, polypropylene, polystyrene, polybutadiene, epoxy resin, fluoropolymer, polyvinyl chloride, polymethyl methacrylate, polyamide, polyimide, polycarbonate, cellulose acetate, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyphenylene sulfide, and polyetherimide. Ceramic materials may include at least one selected from the group consisting of SiO2, Si3N4, Al2O3, Zr2O3, and MgO.

[0072] The adsorbent material layer 30 comprises a conductive material and an organic adsorbent material. Because the adsorbent material layer 30 includes a conductive material, an electric current can flow through it. By flowing an electric current through the adsorbent material layer 30, its resistance can be measured. The conductive material is not particularly limited as long as it is conductive. For example, the conductive material includes at least one selected from the group consisting of carbon materials, conductive polymers, metallic materials, metal oxides, semiconductor materials, superconductors, and complexes.

[0073] Carbon materials include, for example, at least one selected from the group consisting of carbon black, graphite, coke, carbon nanotubes, graphene, and fullerene. Conductive polymers include, for example, at least one selected from the group consisting of polyaniline, polythiophene, polypyrrole, and polyacetylene. Metallic materials include, for example, at least one selected from the group consisting of silver, gold, copper, platinum, and aluminum. Metal oxides include, for example, at least one selected from the group consisting of indium oxide, tin oxide, tungsten oxide, zinc oxide, and titanium oxide. Semiconductor materials include, for example, at least one selected from the group consisting of silicon, gallium arsenide, indium phosphide, and molybdenum sulfide. Superconductors include, for example, those made from YB... a2 Cu3O7 and Tl2Ba2Ca2Cu3O 10 At least one selected from the group consisting of. The complex includes, for example, at least one selected from the group consisting of a complex of tetramethyl-p-phenylenediamine and chloroquinone, a complex of tetracyano-p-benzoquinone dimethane and an alkali metal, a complex of tetrathiofulvalene and a halogen, a complex of iridium and a halocarbonyl compound, and tetracyanoplatinum.

[0074] Conductive materials typically include carbon black. When carbon black is included as a conductive material, the resistance of the adsorbent layer changes more significantly. Therefore, gas detection can be performed more reliably.

[0075] The adsorbent material layer 30 typically comprises particles of conductive material. The average particle diameter of the conductive material particles can be in the range of 10–300 nm. The “average particle diameter” can be measured by observing the surface or cross-section of the adsorbent material layer 30 with an electron microscope and measuring the diameter of any number of particles (e.g., 50) included in the adsorbent material layer 30. The average particle diameter is determined by calculating the average value using the obtained measurements. Alternatively, the diameter of a circle having an area equal to the area of ​​the particle observed with an electron microscope can be considered as the particle diameter.

[0076] The weight ratio of the conductive material to the adsorbent layer 30 can be in the range of 0.05 to 0.95, or 0.25 to 0.95. Alternatively, the weight ratio can be 0.5. When the conductive material is carbon black, the weight ratio of the carbon black to the adsorbent layer 30 can be in the range of 0.25 to 0.95. In this case, current can easily flow from the first conductor 20 or the second conductor 25 to the adsorbent layer 30. Therefore, the resistance of the adsorbent layer 30 can be easily measured.

[0077] Organic adsorbent materials can adsorb gases. When gases are adsorbed by the organic adsorbent material, the volume of the adsorbent material layer 30 changes. The material of the organic adsorbent material is determined based on the type of gas to be detected, the type of conductive material, etc. For example, the material of the organic adsorbent material may include materials sold as stationary phases for gas chromatography columns. For example, the material of the organic adsorbent material may include at least one selected from the group consisting of polymeric materials and low-molecular-weight materials. For example, the organic adsorbent material may include at least one selected from the group consisting of polyalkylene glycols, polyesters, silicones, glycerols, nitriles, dicarboxylic acid monoesters, and aliphatic amines. In this case, the organic adsorbent material can readily adsorb gases.

[0078] Polyalkylene glycols include, for example, polyethylene glycol. Polyesters include, for example, at least one selected from the group consisting of poly(diethylene glycol adipic acid) and poly(ethylene glycol succinate). Silicones include, for example, at least one selected from the group consisting of dimethylsiloxane, phenylmethylsiloxane, trifluoropropylmethylsiloxane, and cyanosiloxane. Glycerides include, for example, diglycerides. Nitriles include, for example, at least one selected from the group consisting of N,N-bis(2-cyanoethyl)formamide and 1,2,3-tris(2-cyanoethoxy)propane. Dicarboxylic acid monoesters include, for example, at least one selected from the group consisting of polyethylene glycol modified with terephthalic acid and diethylene glycol succinate. Aliphatic amines include, for example, tetrahydroxyethylethylenediamine.

[0079] The weight ratio of the organic adsorbent material to the adsorbent layer 30 is determined based on the type of gas to be detected, the type of conductive material, etc. The weight ratio of the organic adsorbent material to the adsorbent layer 30 can range from 0.05 to 0.95.

[0080] The adsorbent material layer 30 may also include additives. Additives may include, for example, dispersants.

[0081] The materials of the first wall portion 11 and the second wall portion 12 are not particularly limited. The materials of the first wall portion 11 and the second wall portion 12 may each be hydrophobic. The materials of the first wall portion 11 and the second wall portion 12 may, for example, comprise hydrophobic polymer materials. Hydrophobic polymer materials may include, for example, at least one selected from the group consisting of polyethylene, polypropylene, polystyrene, polybutadiene, epoxy resin, and fluoropolymers. The material of the first wall portion 11 may be the same as the material of the second wall portion 12. The materials of the first wall portion 11 and the second wall portion 12 may each be the same as the material of the substrate 10.

[0082] Next, the manufacturing method of the gas sensor 100 will be described.

[0083] First, a first conductor 20 and a second conductor 25 are respectively disposed on the substrate 10. The method for disposing the first conductor 20 and the second conductor 25 on the substrate 10 is not particularly limited. For example, by depositing metal on the substrate 10, the first conductor 20 and the second conductor 25 can be disposed on the substrate 10. Examples of methods for depositing metal include sputtering, ion plating, electron beam evaporation, vacuum evaporation, chemical vapor deposition, and chemical vapor deposition.

[0084] Next, insulating layer 40 is fabricated. The method for fabricating insulating layer 40 is not particularly limited. Insulating layer 40 can be fabricated, for example, by preparing a dispersion of an insulating polymer material. The dispersion is obtained by dispersing the insulating polymer material in a coating solvent. The coating solvent includes, for example, at least one selected from the group consisting of water and organic solvents.

[0085] A dispersion is applied to the first conductor 20 and the second conductor 25 with a desired pattern to form a coating film. Printing is an example of a method for forming the coating film. The coating film is then dried to form a precursor layer for the insulating layer 40.

[0086] Next, a first opening 45 and a second opening 46 are formed in the precursor layer of the insulating layer 40. This allows the insulating layer 40 to be fabricated. The method for forming the first opening 45 and the second opening 46 is not particularly limited. For example, the first opening 45 and the second opening 46 can be formed by irradiating the precursor layer of the insulating layer 40 with an ion beam. Alternatively, the first opening 45 and the second opening 46 can also be formed by etching the precursor layer of the insulating layer 40.

[0087] Next, the adsorbent material layer 30 is fabricated. First, a dispersion comprising a conductive material and an organic adsorbent material is prepared. The dispersion is obtained by dispersing the conductive material and the organic adsorbent material in a coating solvent. The coating solvent includes, for example, at least one selected from the group consisting of water and organic solvents. Next, the dispersion is coated onto the insulating layer 40 to form a coating film. By drying the coating film, the adsorbent material layer 30 is formed.

[0088] The adsorbent material layer 30 formed by the above method typically has a uniform thickness in the circumferential direction on the surface of the substrate 10. In the gas sensor 100 of this embodiment, the first conductor 20 and the second conductor 25 have an arc or ring shape when viewed from above. Therefore, the adsorbent material layer 30 has a uniform thickness along the first conductor 20. Similarly, the adsorbent material layer 30 has a uniform thickness along the second conductor 25. At this time, the resistance of the adsorbent material layer 30 can be measured stably.

[0089] When the gas sensor 100 includes a first wall portion 11 and a second wall portion 12, the dispersion liquid can be uniformly coated. That is, the thickness of the adsorbent material layer 30 can be made uniform. When the first wall portion 11 and the second wall portion 12 are hydrophobic, the surface tension generated between the dispersion liquid and each of the first wall portion 11 and the second wall portion 12 is low. Therefore, the thickness of the adsorbent material layer 30 can be made more uniform.

[0090] Next, the method for detecting gas using gas sensor 100 will be explained.

[0091] First, the exposed portion 20a of the first conductor 20 and the exposed portion 25a of the second conductor 25 are respectively connected to the detector. The detector can apply a voltage to the first conductor 20 and the second conductor 25. When a voltage is applied to the first conductor 20 and the second conductor 25, a current flows through the adsorption material layer 30. The detector can measure the resistance of the adsorption material layer 30 based on the current flowing through the adsorption material layer 30.

[0092] Next, the gas sensor 100 is placed in an atmosphere containing a gas. The gas may include, for example, volatile organic compounds. Volatile organic compounds may include, for example, at least one selected from the group consisting of ketones, amines, alcohols, aromatic hydrocarbons, aldehydes, esters, organic acids, hydrogen sulfide, methanethiol, disulfides, and pyrrole.

[0093] When gas comes into contact with the gas sensor 100, the organic adsorbent material of the adsorbent material layer 30 adsorbs the gas. As the organic adsorbent material adsorbs the gas, the volume of the adsorbent material layer 30 changes. Specifically, the adsorbent material layer 30 expands or contracts. This change in volume causes a change in the positional relationship between the conductive materials within the adsorbent material layer 30. In the gas sensor 100, current does not flow from the surface of the first conductor 20 covered by the insulating layer 40 to the adsorbent material layer 30. Current also does not flow from the surface of the second conductor 25 covered by the insulating layer 40 to the adsorbent material layer 30. That is, the number of current paths within the adsorbent material layer 30 is relatively small. Therefore, the change in current paths caused by the change in the positional relationship between the conductive materials is relatively large. If the change in current paths is large, the resistance of the adsorbent material layer 30 changes significantly. Because the resistance of the adsorbent material layer 30 changes significantly, gas can be detected more reliably. According to the gas sensor 100 of this embodiment, gas can be detected even when the gas concentration is in the range of 0.1 to 1000 ppm.

[0094] In this embodiment, the adsorbent material layer 30 has a ring shape when viewed from above. Therefore, when the adsorbent material layer 30 adsorbs gas, it expands or contracts in the radial direction of the virtual circle C1. A plurality of first openings 45a, 45b, 45c, and 45d are located on the virtual circle C2. Furthermore, a plurality of second openings 46a, 46b, 46c, and 46d are located on the virtual circle C3. Since the virtual circles C1, C2, and C3 are concentric, deviations in the current path are suppressed when the adsorbent material layer 30 expands or contracts. In particular, in this embodiment, since the plurality of first openings 45a, 45b, 45c, and 45d and the plurality of second openings 46a, 46b, 46c, and 46d are located on virtual straight lines L1 or L2, deviations in the current path are further suppressed. Thus, changes in the resistance of the adsorbent material layer 30 accompanying changes in the current path can be stably detected. Therefore, the gas sensor 100 can stably detect the gas.

[0095] Next, the gas sensor assembly involved in this embodiment will be described.

[0096] like Figure 4As shown, the gas sensor assembly 200 includes multiple gas sensors 100 and a substrate 210. The substrate 210 is, for example, plate-shaped. The substrate 210 has, for example, a rectangular shape when viewed from above. The substrate 210 has two sets of opposing end faces.

[0097] Each of the plurality of gas sensors 100 is disposed on a substrate 210. Each of the plurality of gas sensors 100 is connected to a detector (not shown). The adsorption material layer 30 of each of at least two gas sensors 100 selected from the plurality of gas sensors 100 can be made of the same material. In this case, the detection accuracy of the gas sensor assembly 200 for a specific gas is improved. Alternatively, the adsorption material layer 30 of each of the at least two gas sensors 100 selected from the plurality of gas sensors 100 can be made of different materials. The types of organic adsorbents included in the adsorption material layer 30 of each of the plurality of gas sensors 100 can also be different. In this case, the plurality of gas sensors 100 exhibit different behaviors for a specific gas. For example, a gas that is difficult to be adsorbed by a particular gas sensor 100 may be adsorbed by other gas sensors 100. Thus, the gas sensor assembly 200 is capable of detecting mixtures of gases including multiple gases.

[0098] The number of gas sensors 100 included in the gas sensor assembly 200 is not particularly limited. For example, the number of gas sensors 100 may be 16. Figure 4 In this configuration, four gas sensors 100 are arranged in a direction from one end face of a pair of end faces of the substrate 210 toward the other end face. Four gas sensors 100 are also arranged in a direction from one end face of another pair of end faces of the substrate 210 toward the other end face.

[0099] (A variation of Implementation Method 1)

[0100] The surface of the substrate 10 surrounded by the first wall portion 11 may not have a circular shape. Figure 5 In the gas sensor 110, the first wall portion 11 includes a plurality of protrusions 11a. The plurality of protrusions 11a each protrude from the outer periphery of the substrate 10 toward the center of gravity of the surface of the substrate 10. The plurality of protrusions 11a each have a fan shape when viewed from above. The surface of the substrate 10 surrounded by the first wall portion 11 has, for example, a gear shape. The number of the plurality of protrusions 11a is not particularly limited. The number of the plurality of protrusions 11a is, for example, 6. Figure 5 In this configuration, each of the plurality of protrusions 11a is not connected to the second wall portion 12. However, the plurality of protrusions 11a may also be connected to the second wall portion 12 individually.

[0101] like Figure 6As shown, multiple protrusions 11a partially cover the upper surface and side surface of the first conductor 20. Multiple protrusions 11a partially cover the upper surface and side surface of the second conductor 25. Multiple protrusions 11a are in contact with both the first conductor 20 and the second conductor 25. The portions of the first conductor 20 covered by the multiple protrusions 11a do not contact the insulating layer 40 or the adsorbent material layer 30. The portions of the second conductor 25 covered by the multiple protrusions 11a do not contact the insulating layer 40 or the adsorbent material layer 30. However, the portions of the first conductor 20 and the portions of the second conductor 25 covered by the multiple protrusions 11a can be covered by the insulating layer 40.

[0102] like Figure 5 As shown, a detection portion 35 is formed between two adjacent protrusions 11a in the circumferential direction on the surface of the substrate 10. The gas sensor 110 typically has a plurality of detection portions 35, the same number as the plurality of protrusions 11a. In each of the plurality of detection portions 35, an insulating layer 40 covers a first conductor 20 and a second conductor 25, respectively. The insulating layer 40 has a first opening 45 and a second opening 46 in each detection portion 35. In each detection portion 35, an adsorbent material layer 30 contacts the first conductor 20 and the second conductor 25 through the first opening 45 and the second opening 46, respectively. In each of the plurality of detection portions 35, the resistance of the adsorbent material layer 30 can be measured.

[0103] When fabricating the adsorbent material layer 30 of the gas sensor 110, the dispersion liquid can be more uniformly applied to each of the plurality of detection sections 35. That is, the thickness of the adsorbent material layer 30 in the gas sensor 110 can be made more uniform.

[0104] (Implementation Method 2)

[0105] The first conductor 20 may not have an arc or ring shape when viewed from above. Similarly, the second conductor 25 may not surround the first conductor 20. Furthermore, the adsorbent material layer 30 may not have a circular or ring shape when viewed from above. Figure 7In the gas sensor 120, the first conductor 20 has a rectangular shape and a strip shape when viewed from above. The second conductor 25 has a rectangular shape and a strip shape when viewed from above. The adsorbent material layer 30 has a rectangular shape when viewed from above. In this embodiment, the adsorbent material layer 30 has a strip shape. The substrate 10 has a rectangular shape when viewed from above. The gas sensor 120 does not have a second wall portion 12. Except for the shape of the first conductor 20, the shape of the second conductor 25, the shape of the adsorbent material layer 30, the shape of the substrate 10, and the presence or absence of the second wall portion 12, the structure of the gas sensor 120 is the same as that of the gas sensor 100 of Embodiment 1. Therefore, for elements common to both the gas sensor 100 of Embodiment 1 and the gas sensor 120 of this embodiment, the same reference numerals are sometimes used, and their descriptions are omitted. That is, the following descriptions related to each embodiment can be applied to each other as long as they are not technically contradictory. Furthermore, the embodiments can be combined with each other as long as they are not technically contradictory.

[0106] The outer periphery 30a of the adsorbent material layer 30 is composed of multiple contour lines 30b, 30c, 30d, and 30e. Contour lines 30b and 30d are opposite to each other. Contour lines 30c and 30e are opposite to each other. Contour lines 30c and 30e extend in a first direction X. Contour lines 30b and 30d extend in a second direction Y. The first direction X and the second direction Y are orthogonal.

[0107] The first conductor 20 and the second conductor 25 extend in the second direction Y. The first conductor 20 and the second conductor 25 are arranged in the first direction X.

[0108] The plurality of first openings 45a, 45b, 45c, and 45d are arranged in a straight line along the second direction Y. In other words, the plurality of first openings 45a, 45b, 45c, and 45d are arranged along the length direction of the first conductor 20. In this embodiment, the plurality of first openings 45a, 45b, 45c, and 45d are arranged at equal intervals along the second direction Y.

[0109] A plurality of second openings 46a, 46b, 46c, and 46d are arranged in a straight line along the second direction Y. In other words, the plurality of second openings 46a, 46b, 46c, and 46d are arranged along the length direction of the second conductor 25. In this embodiment, the plurality of second openings 46a, 46b, 46c, and 46d are arranged at equal intervals along the second direction Y. At least one first opening 45 selected from a plurality of first openings 45 and at least one second opening 46 selected from a plurality of second openings 46 may also be arranged along the first direction X. In this embodiment, first openings 45a and second openings 46a are arranged along the first direction X. First openings 45b and second openings 46b are arranged along the first direction X. First openings 45c and second openings 46c are arranged along the first direction X. First openings 45d and second openings 46d are arranged along the first direction X.

[0110] The gas sensor 120 in this embodiment does not have a second wall portion 12. However, the gas sensor 120 may also have a second wall portion 12. In this case, the shape of the second wall portion 12 may also be prismatic. When the gas sensor 120 has a second wall portion 12, the adsorbent material layer 30 has a frame shape when viewed from above.

[0111] In this embodiment, the adsorbent material layer 30 has a rectangular shape when viewed from above. Therefore, when the adsorbent material layer 30 adsorbs gas, it expands or contracts in both the first direction X and the second direction Y. The adsorbent material layer 30 also expands or contracts in the opposite directions of the first direction X and the second direction Y. A plurality of first openings 45a, 45b, 45c, and 45d are arranged along the second direction Y. Furthermore, a plurality of second openings 46a, 46b, 46c, and 46d are also arranged along the second direction Y. Therefore, when the adsorbent material layer 30 expands or contracts, deviations in the current path are suppressed. Thus, changes in the resistance of the adsorbent material layer 30 accompanying changes in the current path can be stably detected. Therefore, the gas sensor 100 can stably detect gas.

[0112] (Implementation Method 3)

[0113] The gas sensor 120 in Embodiment 2 may also include a plurality of first conductors 20 and a plurality of second conductors 25. A first opening 45 may be formed in each of the plurality of first conductors 20. A second opening 46 may be formed in each of the plurality of second conductors 25. Figure 8 In the gas sensor 130, a plurality of first conductors 20 extend in the second direction Y. The plurality of first conductors 20 are electrically connected by wiring 50. The number of the plurality of first conductors 20 can be in the range of 2 to 10.

[0114] Multiple second conductors 25 extend in opposite directions to the second direction Y. The multiple second conductors 25 are electrically connected via wiring 55. Multiple first conductors 20 and multiple second conductors 25 are arranged alternately in the first direction X. The number of multiple second conductors 25 can be in the range of 2 to 10.

[0115] A plurality of first openings 45a, 45b, 45c, and 45d are arranged in a straight line along a first direction X. In this embodiment, the plurality of first openings 45a, 45b, 45c, and 45d are arranged at equal intervals along the first direction X. A plurality of second openings 46a, 46b, 46c, and 46d are arranged in a straight line along the first direction X. In this embodiment, the plurality of second openings 46a, 46b, 46c, and 46d are arranged at equal intervals along the first direction X.

[0116] In this embodiment, the adsorbent material layer 30 has a rectangular shape when viewed from above. Therefore, when the adsorbent material layer 30 adsorbs gas, it expands or contracts in both the first direction X and the second direction Y. It also expands or contracts in the opposite directions of the first direction X and the second direction Y. A plurality of first openings 45a, 45b, 45c, and 45d are arranged along the first direction X. Furthermore, a plurality of second openings 46a, 46b, 46c, and 46d are also arranged along the first direction X. Therefore, when the adsorbent material layer 30 expands or contracts, deviations in the current path are suppressed. Thus, changes in the resistance of the adsorbent material layer 30 accompanying changes in the current path can be stably detected. Therefore, the gas sensor 100 can stably detect gas.

[0117] Alternatively, the adsorbent material layer 30 may not have the shape illustrated in embodiments 1 to 3. The shape of the adsorbent material layer 30 may be linear, grid-like, or mesh-like. In this case, the adsorbent material layer 30 partially covers both the first conductor 20 and the second conductor 2. Therefore, even if the gas sensor does not have the insulating layer 40, the number of current paths in the adsorbent material layer 30 is relatively small. Based on this adsorbent material layer 30, even if the gas sensor does not have the insulating layer 40, the gas can be detected more reliably due to the large change in resistance of the adsorbent material layer 30.

[0118] [Example]

[0119] This disclosure is specifically described based on embodiments. However, this disclosure is not limited to any of the following embodiments.

[0120] (Sample 1)

[0121] First, a first conductor and a second conductor are respectively disposed on a substrate. The first conductor and the second conductor are each made of platinum. A Si substrate is used as the substrate. The first conductor and the second conductor each have an arc shape when viewed from above. The second conductor surrounds the first conductor.

[0122] Next, the first conductor and the second conductor are respectively covered by a precursor layer of the insulating layer. The precursor layer is made of SiO2. An insulating layer is fabricated by forming a first opening and a second opening in the precursor layer. The first and second openings are circular in shape when viewed from above. The diameters of the first and second openings when viewed from above are both 5 μm. That is, the areas of the first and second openings when viewed from above are both 20 μm². 2 .

[0123] Next, a dispersion comprising a conductive material and an organic adsorbent material is coated onto the insulating layer to form a coating film. Carbon black is used as the conductive material. Polyethylene glycol is used as the organic adsorbent material. By drying the coating film, an adsorbent material layer is formed. The weight ratio of the conductive material to the adsorbent material layer is 0.5. The adsorbent material layer has a ring shape when viewed from above. Thus, the gas sensor of Sample 1 is obtained.

[0124] (Sample 2)

[0125] In addition to fabricating the insulating layer by providing four first openings and four second openings on the precursor layer of the insulating layer, the gas sensor of sample 2 was obtained in the same manner as in Example 1.

[0126] (Sample 3)

[0127] In addition to fabricating the insulating layer by providing eight first openings and eight second openings on the precursor layer of the insulating layer, the gas sensor of sample 3 was obtained in the same manner as in Example 1.

[0128] (Sample 4)

[0129] In addition to fabricating the insulating layer by providing sixteen first openings and sixteen second openings on the precursor layer of the insulating layer, the gas sensor of sample 4 was obtained in the same manner as in Example 1.

[0130] (Sample 5)

[0131] Except for the absence of an insulating layer, the gas sensor of sample 5 was obtained using the same method as in Example 1.

[0132] (Measurement of the rate of change of resistance)

[0133] Samples 1–5 were placed in an atmosphere containing gaseous nonanal, and the rate of change in resistance of the adsorbent layer for each sample was measured. The resistance of the adsorbent layer before adsorbing nonanal was defined as R1. The resistance of the adsorbent layer after adsorbing nonanal was defined as R2. The difference between R1 and R2 was defined as ΔR. The rate of change in resistance C (%) was calculated based on ΔR / R1 × 100. The concentration of nonanal was 0.8 ppm.

[0134] like Figure 9 As shown, compared with the gas sensor of sample 5, the gas sensors of samples 1-4 have a higher rate of change C. Figure 9 The horizontal axis of the graph represents the number of first openings. At the rate of change C of sample 5, gas detection is sometimes insufficient. From Figure 9 It can be seen that the gas sensor of this embodiment can detect gases more reliably.

[0135] The fewer the number of first openings and second openings, the fewer the number of current paths in the adsorption material layer. Figure 9 The graph shows that the fewer the number of current paths in the adsorbent material layer, the greater the rate of change C of the adsorbent material layer's resistance. However, the measurement results from Sample 1 show that when the number of the first opening and the number of the second opening are below a certain value, the value of the rate of change C actually decreases.

[0136] (Sample 6)

[0137] In addition to using four conductors that have a rectangular shape when viewed from above as the first conductor and the second conductor, alternating the arrangement of the multiple first conductors and multiple second conductors in a direction orthogonal to the thickness direction of the substrate, providing a first opening for each of the multiple first conductors, providing a second opening for each of the multiple second conductors, and having the adsorbent material layer have a rectangular shape when viewed from above, the gas sensor of sample 6 was obtained in the same manner as sample 1.

[0138] (Sample 7)

[0139] In addition to using a conductor with a rectangular shape when viewed from above as the first conductor and a conductor with four first openings on the first conductor and four second openings on the second conductor, the gas sensor of sample 7 was obtained in the same way as sample 6.

[0140] (Measurement of the rate of change of resistance)

[0141] Samples 2, 6, and 7 were placed in an atmosphere containing nonanal gas, and the rate of change C (%) of the resistivity of the adsorbent material layer of each sample was measured. The concentration of nonanal was 0.8 ppm.

[0142] like Figure 10 As shown, the gas sensor of sample 2 exhibits a higher rate of change C compared to other gas sensors. This result indicates that, when the adsorbent material layer has a ring shape when viewed from above, the multiple first openings are arranged in an arc shape, and the multiple second openings are arranged in an arc shape, the gas sensor can detect gases more reliably.

[0143] [Industrial Applicability]

[0144] The techniques disclosed in this specification are useful for gas detection, etc.

Claims

1. A gas sensor, comprising: substrate; A first conductor and a second conductor are disposed on the substrate; An adsorption material layer, comprising a conductive material and an organic adsorption material capable of adsorbing gases, is in contact with the first conductor and the second conductor, respectively; and A first wall portion that surrounds the surface of the substrate and is in contact with the adsorbent material layer.

2. The gas sensor according to claim 1, wherein, The material of the first wall portion is hydrophobic.

3. The gas sensor according to claim 1, wherein, The first wall extends above the adsorbent material layer.

4. The gas sensor according to claim 1, wherein, It also includes a second wall portion extending upward from a portion of the surface of the substrate.

5. The gas sensor according to claim 4, wherein, The material of the second wall portion is hydrophobic.

6. The gas sensor according to claim 4, wherein, The second wall extends above the adsorbent material layer.

7. The gas sensor according to claim 4, wherein, The second wall portion is cylindrical or cylindrical in shape.

8. The gas sensor according to claim 1, wherein, The first wall portion has a ring shape when viewed from above.

9. The gas sensor according to claim 1, wherein, The first wall portion has a protrusion that protrudes from the outer periphery of the substrate toward the center of gravity of the surface of the substrate.

10. The gas sensor according to claim 9, wherein, The protruding portion partially covers the first conductor and the second conductor, respectively.

11. The gas sensor according to claim 9, wherein, The first wall portion has two of the aforementioned protrusions. A detection section for measuring the resistance of the adsorbent material layer is formed between the two protrusions.

12. The gas sensor according to claim 1, wherein, The adsorbent material layer partially covers the first conductor and the second conductor, respectively.

13. The gas sensor according to claim 1, wherein, The adsorbent material layer has a circular or ring-shaped appearance when viewed from above. The first conductor has an arc or ring shape when viewed from above. The second conductor has an arc or ring shape when viewed from above.

14. The gas sensor according to claim 13, wherein, The second conductor surrounds the first conductor.

15. The gas sensor according to claim 1, wherein, The substrate is a Si substrate, a metal plate, or a glass plate.

16. The gas sensor according to claim 1, wherein, The organic adsorbent material includes at least one selected from the group consisting of polyalkylene glycols, polyesters, silicones, glycerols, nitriles, dicarboxylic acid monoesters, and aliphatic amines.

17. The gas sensor according to claim 1, wherein, The conductive material includes carbon black.

18. The gas sensor according to claim 17, wherein, The weight ratio of the carbon black to the weight of the adsorbent material layer is in the range of 0.25 to 0.

95.

19. The gas sensor according to claim 1, wherein, The gas sensor is used to detect gases including volatile organic compounds.

20. A gas sensor for detecting a gas including volatile organic compounds, comprising: substrate; A first conductor and a second conductor are disposed on the substrate; An adsorption material layer, comprising an organic adsorption material capable of adsorbing the gas, and in contact with the first conductor and the second conductor respectively; and A first wall portion that surrounds the surface of the substrate and is in contact with the adsorbent material layer.

21. A gas sensor, comprising: substrate; A first conductor and a second conductor are disposed on the substrate; The adsorption material layer includes an organic adsorption material capable of adsorbing gases, and is in contact with the first conductor and the second conductor respectively. A first wall portion surrounding the surface of the substrate and in contact with the adsorbent material layer; as well as A second wall portion extending upward from a portion of the surface of the substrate.

22. The gas sensor according to claim 20 or 21, wherein, When the organic adsorbent material adsorbs the gas, the gas is detected by the change in the resistance of the adsorbent material layer.

23. A gas sensor, comprising: substrate; A first conductor and a second conductor are disposed on the substrate; An insulating layer covers the first conductor and the second conductor, and the insulating layer has a first opening and a second opening, the first opening exposing a portion of the surface of the first conductor and the second opening exposing a portion of the surface of the second conductor. The adsorption material layer includes a conductive material and an organic adsorption material capable of adsorbing gases, and is in contact with the first conductor and the second conductor respectively through the first opening and the second opening. as well as The wall portion surrounding the surface of the substrate and in contact with the adsorbent material layer.

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