Gas identification system and gas identification method

Abstract

A gas identification system (100) comprises: a plurality of gas sensors (10) that each have a sensitive film and that include a first gas sensor group (15A) and a second gas sensor group (15B); a first acquisition unit (41) for acquiring a plurality of first signals output from gas sensors (10A) belonging to the first gas sensor group (15A) exposed to a sample gas; a second acquisition unit (42) for acquiring a plurality of second signals output from gas sensors (10B) belonging to the second gas sensor group (15B) exposed to the sample gas; and a signal processing unit (50) for identifying molecules contained in the sample gas on the basis of the plurality of first signals and the plurality of second signals. The material compositions of the sensitive films of the gas sensors (10A) belonging to the first gas sensor group (15A) are different from each other. The material compositions of the sensitive films of the gas sensors (10B) belonging to the second gas sensor group (15B) are the same.

Description

Gas discrimination system and gas discrimination method

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to gas discrimination systems and methods.

[0002] A gas identification system is known that identifies molecules contained in a sample gas based on a signal output from a gas sensor exposed to the sample gas. Furthermore, using multiple gas sensors in molecular identification can improve identification accuracy compared to using a single gas sensor. For example, Patent Document 1 discloses a gas sensor unit including multiple gas sensors, in which the amount of dopant doped in the sensitive film of each gas sensor is adjusted to make the response characteristics of the sensitive film of each gas sensor to molecules different from one another.

[0003] Japanese Patent Application Publication No. 11-264808

[0004] In identifying molecules contained in a sample gas, the accuracy of molecular identification can be reduced due to various factors, such as the concentration of molecules in the sample gas exposed to the gas sensor. Therefore, further improvement in the accuracy of molecular identification is required.

[0005] Therefore, the present disclosure provides a gas identification system and a gas identification method that can improve the accuracy of molecular identification.

[0006] A gas identification system according to one aspect of the present disclosure includes: a plurality of gas sensors each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong; and a second gas sensor group to which some of the plurality of gas sensors belong; a first acquisition unit that acquires a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the first gas sensor group exposed to a sample gas; a second acquisition unit that acquires a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the second gas sensor group exposed to the sample gas; and a signal processing unit that identifies molecules contained in the sample gas based on the first signals acquired by the first acquisition unit and the second signals acquired by the second acquisition unit, wherein the sensitive films of the gas sensors in the first gas sensor group have different material compositions and the sensitive films of the gas sensors in the second gas sensor group have the same material composition.

[0007] A gas identification method according to one aspect of the present disclosure is a gas identification method using a plurality of gas sensors, each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong and a second gas sensor group to which other of the plurality of gas sensors belong, the method comprising: acquiring a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the first gas sensor group exposed to a sample gas; acquiring a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the second gas sensor group exposed to the sample gas; and identifying molecules contained in the sample gas based on the acquired first signals and second signals; the sensitive films of the gas sensors in the first gas sensor group have different material compositions, while the sensitive films of the gas sensors in the second gas sensor group have the same material composition.

[0008] These comprehensive or specific aspects may be realized by a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM (Compact Disc-Read Only Memory), or may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program, a program product, and a recording medium.

[0009] According to the present disclosure, the accuracy of molecular identification can be improved.

[0010] FIG. 1 is a block diagram showing a schematic configuration of a gas identification system according to an embodiment. FIG. 2 is a top view showing an example of a gas sensor according to an embodiment. FIG. 3 is a schematic view showing an example of the configuration of an exposure unit according to an embodiment. FIG. 4 is a plan view showing an example of a planar layout of a gas sensor group according to an embodiment. FIG. 5 is a flowchart showing an example of operation of the gas identification system according to an embodiment. FIG. 6 is a diagram showing an example of a signal output from a gas sensor according to an embodiment. FIG. 7 is a diagram showing an example of a change in a second signal output by a gas sensor belonging to a second gas sensor group arranged in the planar layout shown in FIG. 4. FIG. 8 is a plan view showing a first example of another planar layout of a gas sensor group according to an embodiment. FIG. 9 is a plan view showing a second example of another planar layout of a gas sensor group according to an embodiment. FIG. 10 is a plan view showing a third example of another planar layout of a gas sensor group according to an embodiment. FIG. 11 is a flowchart showing another example of operation of the gas identification system according to an embodiment. FIG. 12A is a diagram showing an example of a change in a second signal output by a gas sensor belonging to the second gas sensor group arranged in the planar layout shown in FIG. 10. 12B is a diagram showing an example of a change in a second signal output by a gas sensor belonging to the second gas sensor group arranged in the planar layout shown in FIG. 10 . FIG. 12C is a diagram showing an example of a change in a second signal output by a gas sensor belonging to the second gas sensor group arranged in the planar layout shown in FIG. 10 . FIG. 12D is a diagram showing an example of a change in a second signal output by a gas sensor belonging to the second gas sensor group arranged in the planar layout shown in FIG. 10 . FIG. 13 is a plan view showing an example of a planar layout of a gas sensor group according to a modified example of the embodiment. FIG. 14 is a diagram showing an example of a change in a second signal output by a gas sensor belonging to the second gas sensor group arranged in the planar layout shown in FIG. 13 . FIG. 15 is a plan view showing a first example of another planar layout of a gas sensor group according to a modified example of the embodiment. FIG. 16 is a plan view showing a second example of another planar layout of a gas sensor group according to a modified example of the embodiment.

[0011] (Summary of the Present Disclosure) As an overview of the present disclosure, examples of a gas identifying system and a gas identifying method according to the present disclosure are described below.

[0012] For example, a gas identification system according to a first aspect of the present disclosure includes: a plurality of gas sensors each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong; and a second gas sensor group to which some of the plurality of gas sensors belong; a first acquisition unit that acquires a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the first gas sensor group exposed to a sample gas; a second acquisition unit that acquires a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors in the second gas sensor group exposed to the sample gas; and a signal processing unit that identifies molecules contained in the sample gas based on the first signals acquired by the first acquisition unit and the second signals acquired by the second acquisition unit, wherein the material compositions of the sensitive films of the gas sensors in the first gas sensor group are different from each other, and the material compositions of the sensitive films of the gas sensors in the second gas sensor group are the same.

[0013] As a result, because the gas sensors in the first gas sensor group have different sensitive film material compositions, information regarding differences in molecular adsorption behavior due to differences in sensitive film material composition can be obtained from the multiple first signals and used to identify molecules contained in the sample gas. Furthermore, because the gas sensors in the second gas sensor group have the same sensitive film material composition, the differences in the multiple second signals can be used to obtain information regarding the sample gas that is free of the influence of differences in the sensitive film material composition. Therefore, by using not only the multiple first signals but also the multiple second signals to identify molecules contained in the sample gas, the gas identification system according to this aspect can perform identification using different types of information, thereby improving the accuracy of identification.

[0014] Furthermore, for example, a gas identification system according to a second aspect of the present disclosure is the gas identification system according to the first aspect, wherein the second gas sensor group includes two or more identically shaped gas sensors, where the sensitive membranes have the same shape.

[0015] As a result, since the sensitive films of the gas sensors belonging to the second gas sensor group are identical in composition material and shape to one another, differences between the plurality of second signals can be regarded as differences in the concentrations of molecules to be identified contained in the sample gas, etc. Therefore, it is possible to obtain information about the concentration distribution of the molecules to be identified from the layout of the gas sensors belonging to the second gas sensor group and the plurality of second signals, and the information about the concentration distribution can be used to identify the molecules contained in the sample gas.

[0016] Furthermore, for example, a gas identification system according to a third aspect of the present disclosure is the gas identification system according to the second aspect, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more identically shaped gas sensors are arranged along a predetermined direction without any gas sensors belonging to the first gas sensor group intervening therebetween.

[0017] This allows two or more gas sensors of the same shape to be arranged in series, thereby improving the accuracy of detecting the concentration distribution of molecules to be identified contained in the sample gas.

[0018] Furthermore, for example, a gas identification system according to a fourth aspect of the present disclosure is the gas identification system according to the second aspect, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more identically shaped gas sensors are arranged along a predetermined direction with at least one of the gas sensors belonging to the first gas sensor group interposed therebetween.

[0019] This allows the number of gas sensors having the same shape to be reduced even when the number of gas sensors is increased.

[0020] Furthermore, for example, a gas identification system according to a fifth aspect of the present disclosure is the gas identification system according to the third or fourth aspect, further comprising a housing in which the plurality of gas sensors are disposed, and the predetermined direction is parallel to the direction in which the sample gas flows through the housing.

[0021] This allows the second gas sensor group to effectively detect the concentration distribution of molecules to be identified that are contained in the sample gas within the container.

[0022] Furthermore, for example, a gas identification system according to a sixth aspect of the present disclosure is the gas identification system according to the second aspect, wherein the plurality of gas sensors are arranged in a matrix, and the two or more identically shaped gas sensors are arranged in predetermined rows and predetermined columns.

[0023] This allows the second gas sensor group to detect the two-dimensional concentration distribution of the molecules to be identified contained in the sample gas.

[0024] Furthermore, for example, a gas identification system according to a seventh aspect of the present disclosure is the gas identification system according to the second aspect, wherein the plurality of gas sensors includes a plurality of gas sensor sets in which one or more identical-shaped gas sensors of the two or more identical-shaped gas sensors and one or more gas sensors belonging to the first gas sensor group are arranged adjacent to each other, and the plurality of gas sensor sets are arranged two-dimensionally.

[0025] This allows the second gas sensor group to detect the two-dimensional concentration distribution of the molecules to be identified contained in the sample gas.

[0026] Furthermore, for example, a gas identification system according to an eighth aspect of the present disclosure is the gas identification system according to any one of the first to seventh aspects, wherein the second gas sensor group includes two or more non-identically shaped gas sensors, that is, two or more gas sensors having sensitive membranes with different shapes.

[0027] This makes it possible to obtain information about the difference in response characteristics of two or more gas sensors with different shapes to a sample gas due to differences in the shapes of the sensitive films.

[0028] Furthermore, for example, a gas identification system according to a ninth aspect of the present disclosure is the gas identification system according to the eighth aspect, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more non-identically shaped gas sensors are arranged along a predetermined direction without any gas sensors belonging to the first gas sensor group intervening therebetween.

[0029] This allows the second gas sensor group to detect, for example, the local concentration of molecules to be identified contained in the sample gas.

[0030] Furthermore, for example, a gas identification system according to a tenth aspect of the present disclosure is the gas identification system according to the eighth aspect, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more non-identically shaped gas sensors are arranged along a predetermined direction with at least one of the gas sensors belonging to the first gas sensor group interposed therebetween.

[0031] This makes it possible to reduce the number of gas sensors having two or more different shapes even when the number of gas sensors is large.

[0032] Furthermore, for example, a gas identification system according to an eleventh aspect of the present disclosure is the gas identification system according to the eighth or ninth aspect, further comprising a housing in which the plurality of gas sensors are disposed, and the predetermined direction is perpendicular to the direction in which the sample gas flows through the housing.

[0033] This allows the second gas sensor group to effectively detect the local concentration of molecules to be identified that are contained in the sample gas within the container.

[0034] Furthermore, for example, a gas identification system according to a twelfth aspect of the present disclosure is the gas identification system according to the eighth aspect, wherein the plurality of gas sensors are arranged two-dimensionally, the second gas sensor group includes a plurality of non-identical-shaped gas sensor sets in which the two or more non-identical-shaped gas sensors are arranged adjacent to each other, and at least one of the gas sensors belonging to the first gas sensor group is arranged between the plurality of non-identical-shaped gas sensor sets.

[0035] This allows the second gas sensor group to detect the concentration distribution of molecules to be identified contained in the sample gas.

[0036] Furthermore, for example, a gas identification system according to a thirteenth aspect of the present disclosure is the gas identification system according to any one of the eighth to twelfth aspects, wherein the two or more non-identically shaped gas sensors have sensitive films with different thicknesses, and the thinner the sensitive films, the higher the sensitivity.

[0037] This makes it possible to realize the second gas sensor group including highly sensitive gas sensors simply by reducing the thickness of the sensitive film.

[0038] Furthermore, for example, a gas identification system according to a fourteenth aspect of the present disclosure is the gas identification system according to any one of the first to thirteenth aspects, wherein the number of gas sensors belonging to the first gas sensor group is equal to or greater than the number of gas sensors belonging to the second gas sensor group.

[0039] This increases the number of gas sensors belonging to the first gas sensor group, and increases the amount of information obtained from the first gas sensor group regarding differences in molecular adsorption behavior due to differences in the material composition of the sensitive film, thereby improving the accuracy of identifying molecules contained in the sample gas.

[0040] Furthermore, for example, a gas identification system according to a fifteenth aspect of the present disclosure is the gas identification system according to any one of the first to fourteenth aspects, wherein the signal processing unit performs an identification process using the plurality of first signals to identify molecules contained in the sample gas, and performs a correction process on the plurality of first signals based on the plurality of second signals before performing the identification process.

[0041] This allows the multiple first signals used in the identification process to be corrected, thereby improving the ability to identify molecules contained in the sample gas.

[0042] Furthermore, for example, a gas identification system according to a sixteenth aspect of the present disclosure is the gas identification system according to the fifteenth aspect, wherein the material composition of the sensitive film of each gas sensor in the second gas sensor group is different from the material composition of the sensitive film of any gas sensor in the first gas sensor group.

[0043] This makes it possible to obtain information about differences in molecular adsorption behavior due to differences in the material composition of the sensitive film from the gas sensors belonging to the second gas sensor group as well.

[0044] Furthermore, for example, a gas identification system according to a seventeenth aspect of the present disclosure is the gas identification system according to the fifteenth or sixteenth aspect, wherein the signal processor further uses at least one second signal from the plurality of second signals in the identification process.

[0045] This allows the second signal to also be used in the identification process, thereby improving the accuracy of identifying molecules contained in the sample gas.

[0046] Furthermore, for example, a gas identification system according to an eighteenth aspect of the present disclosure is the gas identification system according to any one of the fifteenth to seventeenth aspects, wherein the signal processing unit performs correction processing on the plurality of first signals based on the plurality of second signals and the positions of each gas sensor in the first gas sensor group.

[0047] This enables correction of the first signal according to the position of each gas sensor belonging to the first gas sensor group.

[0048] Furthermore, for example, a gas identification system according to a nineteenth aspect of the present disclosure is the gas identification system according to any one of the first to eighteenth aspects, wherein the signal processing unit selects one or more first signals from the plurality of first signals based on the plurality of second signals, and identifies molecules contained in the sample gas using only the one or more first signals among the plurality of first signals.

[0049] This makes it possible to identify molecules contained in the sample gas while excluding the first signal that reduces the accuracy of the identification.

[0050] Furthermore, for example, a gas identification method according to a twentieth aspect of the present disclosure is a gas identification method using a plurality of gas sensors, each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong and a second gas sensor group to which other of the plurality of gas sensors belong, the method comprising: acquiring a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the first gas sensor group exposed to a sample gas; acquiring a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the second gas sensor group exposed to the sample gas; and identifying molecules contained in the sample gas based on the acquired first signals and second signals; the material composition of the sensitive film of each of the gas sensors belonging to the first gas sensor group is different from that of each of the gas sensors belonging to the second gas sensor group, and the material composition of the sensitive film of each of the gas sensors belonging to the second gas sensor group is the same.

[0051] This improves the accuracy of molecular identification, similar to the gas identification system according to the first aspect described above.

[0052] Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, steps, step order, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not recited in independent claims will be described as optional components.

[0053] Furthermore, in this specification, terms indicating relationships between elements such as parallelism, terms indicating the shapes of elements, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0054] In addition, the drawings are not necessarily strict illustrations, and the same reference numerals are used to designate substantially the same components in the drawings, and redundant explanations are omitted or simplified.

[0055] Furthermore, in this specification, unless otherwise specified, ordinal numbers such as "first" and "second" do not refer to the number or order of components, but are used to avoid confusion between similar components and to distinguish between components.

[0056] (Embodiment) [Configuration] First, the configuration of a gas identifying system according to an embodiment will be described.

[0057] Fig. 1 is a block diagram showing a schematic configuration of gas identification system 100 according to the present embodiment. Solid arrows in Fig. 1 indicate possible flows of signals and information, but the flows of signals and information shown in Fig. 1 are merely examples, and the flows of signals and information in gas identification system 100 according to the present embodiment are not limited to the example shown in Fig. 1.

[0058] 1 , gas identification system 100 according to the present embodiment includes detection device 101 and identification device 102. Detection device 101 includes gas sensor group 15 including a plurality of gas sensors 10, exposure unit 20, and control unit 30. Identification device 102 includes acquisition unit 40, signal processing unit 50, and storage unit 90.

[0059] Gas identification system 100 is a system for identifying molecules contained in a sample gas. Gas identification system 100 identifies which types of molecules are contained in the sample gas from among multiple types of molecules, based on, for example, outputs of multiple gas sensors 10 exposed to the sample gas.

[0060] The sample gas contains molecules to be identified, such as volatilized organic compounds. The sample gas may contain multiple types of molecules to be identified. The molecules to be identified may be inorganic gas molecules such as ammonia, hydrogen sulfide, and carbon monoxide. The sample gas may be, for example, gas collected from food, exhaled breath collected from a human body, air surrounding a human body, or air collected from a room in a building.

[0061] Each of the multiple gas sensors 10 (specifically, the sensitive film 11 described below) has an electrical characteristic value that changes in response to the adsorption of molecules, and outputs a signal corresponding to the electrical characteristic value. The signal output by the gas sensor 10 changes in response to the adsorption concentration of molecules. Furthermore, when different types of molecules are adsorbed by the gas sensor 10, the output signal may differ even for the same adsorption concentration. The gas sensor 10 may be, for example, an electrochemical type, a semiconductor type, a field-effect transistor type, a surface acoustic wave type, a quartz oscillator type, or a resistance change type gas sensor.

[0062] 2 is a top view showing an example of a gas sensor 10 according to the present embodiment. As shown in FIG. 2, the gas sensor 10 includes, for example, a sensitive membrane 11 and a pair of electrodes 12 and 13 electrically connected to the sensitive membrane 11. The sensitive membrane 11 and the pair of electrodes 12 and 13 are provided on, for example, a substrate 14. Two or more of the gas sensors 10 constituting the gas sensor group 15 may share the substrate 14.

[0063] The sensitive film 11 has an electrical resistance value, which is an electrical characteristic value, that changes depending on, for example, the adsorption concentration of molecules. A signal corresponding to the electrical resistance value of the sensitive film 11 of the gas sensor 10 is acquired by the acquisition unit 40 as, for example, a voltage signal or a current signal via the pair of electrodes 12 and 13. The electrical resistance of the sensitive film 11 between the pair of electrodes 12 and 13 is converted into a voltage signal or a current signal by, for example, a detector (not shown). The electrical resistance of the sensitive film 11 is converted into a voltage using, for example, a bridge circuit, and the voltage is amplified as necessary and output as a signal indicating the electrical resistance of the sensitive film 11.

[0064] The sensitive membrane 11 is composed of, for example, a resin material, which is an adsorbent that adsorbs molecules to be identified by the gas identification system 100, and conductive particles dispersed in the resin material. The conductive particles form a conductive network within the resin material. With this configuration, the resin material expands upon adsorption of molecules to the resin material, changing the structure of the network formed by the conductive particles, thereby changing the electrical resistance value of the sensitive membrane 11. Examples of the resin material include polyalkylene glycol resin, polyester resin, and silicone resin. The resin material is, for example, a material commercially available as a stationary phase for gas chromatography columns. From the standpoint of durability and molecular adsorption, the resin material may be, for example, a silicone resin commercially available as a stationary phase for columns, having various substituents, such as phenyl groups and methyl groups, on its side chains. The conductive particles are, for example, particles made of a metal or a conductive carbon material. A specific example of the conductive particles is carbon black. The sensitive membrane 11 is not limited to a composition of a resin material and conductive particles; it may be any material whose electrical characteristic value changes upon adsorption of molecules to be identified.

[0065] The gas sensors 10 constituting the gas sensor group 15 include a first gas sensor group 15A to which some of the gas sensors 10 belong, and a second gas sensor group 15B to which other of the gas sensors 10 belong. The first gas sensor group 15A is made up of the gas sensors 10A that are some of the gas sensors 10. The second gas sensor group 15B is made up of the gas sensors 10B that are some of the gas sensors 10.

[0066] In this specification, the gas sensor 10 may be described as being distinguished between the gas sensor 10A and the gas sensor 10B as necessary. When the gas sensor 10 is referred to without any particular distinction, the description applies to all gas sensors 10, including the gas sensor 10A and the gas sensor 10B. This also applies when the gas sensor 10 is distinguished between a type other than the gas sensor 10A and the gas sensor 10B, as in the modified examples described below.

[0067] The gas sensors 10A constituting the first gas sensor group 15A are gas sensors that output signals for identifying molecules contained in a sample gas. The material compositions of the sensitive films 11 of the gas sensors 10A belonging to the first gas sensor group 15A are different from each other. Here, "different material compositions" refers to differences in at least one of the type of material contained in the sensitive film 11 and, if the sensitive film 11 contains two or more materials, the blending ratios of the two or more materials. In this embodiment, for example, the types of resin materials contained in the sensitive films 11 of the gas sensors 10A are different from each other. "Different types of resin materials" refers to differences in at least the molecular weight or composition formula. For example, in the case of commercially available resin materials, not only are resin materials with different names different, but also resins with the same name but different grade names are considered different resin materials. The composition formulas of the resin materials contained in the sensitive films 11 of the gas sensors 10A may be different from each other. Sensitive films 11 with different material compositions exhibit different adsorption behaviors for the same type of molecules. In particular, the sensitive films 11 made of different types of resin materials (for example, composition formulas) have large differences in molecular adsorption behavior.

[0068] The compounding ratio of the resin material to the conductive particles and the type of the conductive particles in the sensitive film 11 of each gas sensor 10A are, for example, the same as each other. Alternatively, either the compounding ratio of the resin material to the conductive particles or the type of the conductive particles in the sensitive film 11 of each gas sensor 10A may be the same as each other.

[0069] The gas sensors 10B constituting the second gas sensor group 15B are gas sensors that output signals to improve the identification performance when identifying molecules contained in a sample gas. The material composition of the sensitive film 11 of each gas sensor 10B belonging to the second gas sensor group 15B is identical. Here, "same material composition" means that all of the types of materials contained in the sensitive film 11 and, if the sensitive film 11 contains two or more materials, the blending ratios of those two or more materials are the same. The same material composition of the sensitive film 11 ensures that the interactions occurring between the materials of the sensitive film 11 and the same types of molecules are the same. Furthermore, the material composition of the sensitive film 11 of each gas sensor 10B belonging to the second gas sensor group 15B is different from the material composition of the sensitive film 11 of any of the gas sensors 10A belonging to the first gas sensor group 15A, for example.

[0070] In this embodiment, the sensitive films 11 of the gas sensors 10B belonging to the second gas sensor group 15B have the same shape. In this embodiment, the gas sensors 10B are an example of gas sensors with the same shape. Since the material composition and shape of the sensitive films 11 of the gas sensors 10B are the same, the response characteristics of the gas sensors 10B to the same type of molecules are the same. The response characteristics to molecules may also be referred to as sensitivity characteristics.

[0071] The exposure unit 20 is an exposure mechanism that exposes the plurality of gas sensors 10 to gas during a predetermined measurement period under the control of the control unit 30. For example, the exposure unit 20 exposes the plurality of gas sensors 10 to gas during a measurement period consisting of a first period, a second period following the first period, and a third period following the second period. For example, the exposure unit 20 exposes the plurality of gas sensors 10 to a sample gas containing molecules to be identified during the second period of the measurement period. For example, the exposure unit 20 exposes the plurality of gas sensors 10 to the sample gas only during the second period of the measurement period, and does not expose the plurality of gas sensors 10 to the sample gas during the first and third periods. As a result, the concentration of molecules to be identified around the plurality of gas sensors 10 during the second period is higher than during the first and third periods, making it easier for the molecules to be identified to be adsorbed to the plurality of gas sensors 10 during the second period. In other words, during the second period of the measurement period in which the multiple gas sensors 10 are exposed to the sample gas, the exposure unit 20 exposes the multiple gas sensors 10 to the sample gas under conditions in which the molecules contained in the sample gas are more likely to be adsorbed by the multiple gas sensors 10 than during the first and third periods.

[0072] The exposure unit 20 may also expose the multiple gas sensors 10 to a reference gas during the first and third periods. The reference gas has a different composition from the sample gas and serves as a reference for measurement. The reference gas is, for example, a gas that does not contain the molecules to be identified, or the concentration of the molecules to be identified is significantly lower than that of the sample gas (for example, less than one-tenth the concentration of the molecules in the sample gas). The composition of the reference gas does not substantially change with each measurement. The reference gas is, for example, a gas composed of molecules that are less likely to be adsorbed by the sensitive films 11 of the multiple gas sensors 10 than the molecules to be identified.

[0073] Specific examples of the reference gas include industrial or analytical air, inert gases such as nitrogen or rare gases that are substantially free of water molecules and organic compounds, and gases obtained by removing the molecules to be identified from the sample gas using a filter, etc. By exposing the gas sensors 10 to the reference gas in this way during the first and third periods, the signals output from the gas sensors 10 are stabilized for each measurement even when the ambient environment of the gas sensors 10 changes, thereby improving the identification accuracy.

[0074] In the following description of this embodiment, we will mainly describe an example in which the exposure unit 20 exposes multiple gas sensors 10 to a sample gas during the second period, and exposes multiple gas sensors 10 to a reference gas during the first and third periods.

[0075] A specific configuration of the exposure section 20 will be described. Fig. 3 is a schematic diagram showing an example of the configuration of the exposure section 20 according to the present embodiment. As shown in Fig. 3, the exposure section 20 has, for example, a storage section 21, a three-way electromagnetic valve 22, an intake pump 23, and a plurality of pipes 25a, 25b, 25c, 25d, and 25e.

[0076] The control unit 30 controls the operation of the exposure unit 20. The control unit 30 is realized by a microcomputer or a processor that has a built-in program that performs the processes described above and below. The control unit 30 may also be realized by a dedicated logic circuit that performs the processes described above and below.

[0077] One end of the pipe 25a is provided with an intake port 26a for introducing a sample gas. The intake port 26a is provided, for example, in a space filled with the sample gas. One end of the pipe 25b is provided with an intake port 26b for introducing a reference gas. The intake port 26b is provided, for example, in a space filled with the reference gas. One end of the pipe 25e is provided with an exhaust port 26e for discharging the introduced sample gas and reference gas.

[0078] The housing 21 is a box-shaped container that houses a gas sensor group 15 made up of a plurality of gas sensors 10. For example, the plurality of gas sensors 10 are arranged in an array inside the housing 21. One end of each of a pipe 25c and a pipe 25d is connected to the housing 21. When an intake pump 23 (described later) is operated, gas flows from one end of the pipe 25c to one end of the pipe 25d. The gas sensor group 15 is disposed in the flow path through which the gas flows.

[0079] The sample gas introduced through intake port 26a is introduced into the storage section 21 via pipe 25a, three-way solenoid valve 22, and pipe 25c. The reference gas introduced through intake port 26b is introduced into the storage section 21 via pipe 25b, three-way solenoid valve 22, and pipe 25c. The sample gas and reference gas introduced into the storage section 21 are exhausted from exhaust port 26e via pipe 25d, intake pump 23, and pipe 25e.

[0080] Here, we will explain the arrangement of the multiple gas sensors 10 that make up the gas sensor group 15 within the housing portion 21. The multiple gas sensors 10 are, for example, arranged two-dimensionally within the housing portion 21, and the sensitive membranes 11 of the multiple gas sensors 10 are located on the same plane.

[0081] FIG. 4 is a plan view showing an example of the planar layout of a gas sensor group 15 according to this embodiment. In FIG. 4, each of the gas sensors 10 constituting the gas sensor group 15 is schematically shown as a rectangle. The plan view shown in FIG. 4 is a plan view of the gas sensors 10 positioned on the same plane as viewed from the thickness direction of the sensitive film 11 of each of the gas sensors 10. In addition, in FIG. 4, for the purpose of distinction, the gas sensor 10A belonging to the first gas sensor group 15A and the gas sensor 10B belonging to the second gas sensor group 15B are marked with different patterns. This also applies to the plan views showing the planar layout of the gas sensor group 15 described below.

[0082] As shown in Fig. 4, the gas sensors 10 constituting the gas sensor group 15 are arranged, for example, in a matrix. In the example shown in Fig. 4, the gas sensors 10 are arranged in multiple rows and multiple columns along row and column directions that are perpendicular to each other. In the example shown in Fig. 4, the row direction is parallel to the direction in which gas flows in the storage portion 21, and the column direction is perpendicular to the direction in which gas flows in the storage portion 21. In the example shown in Fig. 4, the gas sensors 10 are arranged in three rows and four columns, but the number and arrangement of the gas sensors 10 can be changed depending on the purpose. In addition, the number of rows or columns in which the gas sensors 10 are arranged may be one.

[0083] As shown in FIG. 4 , the gas sensors 10B belonging to the second gas sensor group 15B are arranged in the row direction without any gas sensors 10A belonging to the first gas sensor group 15A in between. In addition, in the column direction, gas sensors 10A are arranged in addition to the gas sensors 10B arranged in the row direction. As will be described in detail later, by arranging the gas sensors 10B in the row direction parallel to the direction in which the sample gas flows through the storage section 21, the concentration distribution of molecules to be identified contained in the sample gas in that direction can be detected by the gas sensors 10B. Furthermore, because the gas sensors 10B are arranged without any gas sensors 10A in between, the detection accuracy of the concentration distribution can be improved. In the example shown in FIG. 4 , the gas sensors 10B are arranged in the third row at the end in the column direction, but the gas sensors 10B may be arranged in any row.

[0084] The number of gas sensors 10A belonging to the first gas sensor group 15A is, for example, equal to or greater than the number of gas sensors 10B belonging to the second gas sensor group 15B. The number of gas sensors 10A belonging to the first gas sensor group 15A may be greater than the number of gas sensors 10B belonging to the second gas sensor group 15B. In the example shown in FIG. 4 , the number of gas sensors 10A belonging to the first gas sensor group 15A is an integer multiple of the number of gas sensors 10B belonging to the second gas sensor group 15B.

[0085] Referring again to FIG. 3 , the three-way solenoid valve 22 is a solenoid valve for switching the gas introduced into the storage section 21. The three-way solenoid valve 22 has an input port P1 connected to the other end of the pipe 25a, an input port P2 connected to the other end of the pipe 25b, and an output port P3 connected to the other end of the pipe 25c. The three-way solenoid valve 22 has each port controlled by the control unit 30 for opening and closing. The three-way solenoid valve 22 switches between a first state in which the input port P1 and the output port P3 are electrically connected and a second state in which the input port P2 and the output port P3 are electrically connected under the control of the control unit 30. In the first state, the input port P1 and the output port P3 are open, and the input port P2 is closed. In the second state, the input port P2 and the output port P3 are open, and the input port P1 is closed. Note that instead of the three-way solenoid valve 22, a valve driven by a power other than electromagnetic power may be provided.

[0086] The intake pump 23 is a pump for introducing the sample gas and the reference gas into the storage unit 21 and discharging the introduced sample gas and reference gas from the exhaust port 26e. The operation of the intake pump 23 is controlled by the control unit 30. The intake port of the intake pump 23 is connected to the other end of the pipe 25d. The exhaust port of the intake pump 23 is connected to the other end of the pipe 25e.

[0087] With this configuration, when the intake pump 23 is operating and the three-way solenoid valve 22 is in the first state, the sample gas is introduced into the storage unit 21. As a result, the exposure unit 20 exposes the multiple gas sensors 10 to the sample gas. Also, when the intake pump 23 is operating and the three-way solenoid valve 22 is in the second state, the reference gas is introduced into the storage unit 21. As a result, the exposure unit 20 exposes the multiple gas sensors 10 to the reference gas. By controlling the three-way solenoid valve 22 in this way, the multiple gas sensors 10 are exposed only to the sample gas when the three-way solenoid valve 22 is in the first state, and the multiple gas sensors 10 are exposed only to the reference gas when the three-way solenoid valve 22 is in the second state.

[0088] The configuration of the exposure unit 20 is not limited to the configuration shown in FIG. 3 , and is not particularly limited as long as it can expose multiple gas sensors 10 to the sample gas. For example, the exposure unit 20 may be configured such that the sample gas and the reference gas are introduced into the storage unit 21 through separate pipes without passing through the three-way solenoid valve 22. The exposure unit 20 may also be configured without the intake pump 23, in which a carrier gas is constantly flowing into the storage unit 21 to mix the sample gas into the carrier gas. Alternatively, the reference gas may not be introduced, and the storage unit 21 may be evacuated by the intake pump 23 after the multiple gas sensors 10 are exposed to the sample gas. The exposure unit 20 may also have a temperature controller for adjusting the temperature of the gas sensor group 15. The multiple gas sensors 10 may be exposed to the sample gas throughout the entire measurement period, and the temperature of the gas sensor group 15 in the second period may be lower than in the first and third periods, thereby creating conditions in which odor molecules contained in the sample gas are more likely to adsorb to the gas sensor 10 during the second period than during the first and third periods. In this case, the accommodation unit 21 that accommodates the gas sensor group 15 does not have to have a sealed structure as shown in the figure, and may be, for example, a container with an open top that accommodates the gas sensor group 15 or a substrate on which the gas sensor group 15 is disposed. The exposure unit 20 may further include various removal filters that remove moisture or particulates from the sample gas and reference gas, electromagnetic adjustment valves that adjust the flow rate of each pipe, check valves that prevent backflow in each pipe, etc. The exposure unit 20 may also have a mechanism for adjusting the humidity inside the accommodation unit 21.

[0089] 1 , the acquisition unit 40 acquires signals output from each of the plurality of gas sensors 10. The acquisition unit 40 acquires, for example, a voltage signal or a current signal as a signal output corresponding to the electrical resistance value of the sensitive film 11 of each of the plurality of gas sensors 10.

[0090] The acquisition unit 40 includes a first acquisition unit 41 and a second acquisition unit 42 .

[0091] The first acquisition unit 41 acquires a plurality of first signals output from each of the gas sensors 10A belonging to the first gas sensor group 15A exposed to the sample gas, the first signals corresponding to the electrical characteristic values ​​of the sensitive films 11. The plurality of first signals correspond one-to-one to the plurality of gas sensors 10A.

[0092] The second acquisition unit 42 acquires a plurality of second signals output from each of the gas sensors 10B belonging to the second gas sensor group 15B exposed to the sample gas, the second signals corresponding to the electrical characteristic values ​​of the sensitive membranes 11. The second signals correspond one-to-one to the gas sensors 10B.

[0093] The signal processing unit 50 identifies molecules contained in the sample gas based on the plurality of first signals acquired by the first acquisition unit 41 and the plurality of second signals acquired by the second acquisition unit 42. In identifying molecules contained in the sample gas, the signal processing unit 50 may further use information regarding the arrangement of the plurality of gas sensors 10. The information regarding the arrangement of the plurality of gas sensors 10 is, for example, information indicating the positional relationship between the gas sensor 10A belonging to the first gas sensor group 15A and the gas sensor 10B belonging to the second gas sensor group 15B.

[0094] The signal processing unit 50 includes a first processing unit 51 and a second processing unit 52 .

[0095] The first processing unit 51 identifies molecules contained in the sample gas by performing an identification process using a plurality of first signals. The first processing unit 51, for example, extracts a plurality of feature amounts from the plurality of first signals and performs the identification process based on the extracted feature amounts. The first processing unit 51, for example, extracts one or more feature amounts from each first signal. The first processing unit 51 may also extract a feature amount to be used in the identification process from at least one of the plurality of second signals. In the identification process, the first processing unit 51 uses, for example, the extracted feature amounts and a trained logical model for identifying molecules contained in the sample gas. As part of the identification process, the first processing unit 51 inputs the plurality of feature amounts to the trained logical model. The trained logical model, for example, receives the feature amounts corresponding to each gas sensor 10A as input and outputs an identification result for the molecules contained in the sample gas.

[0096] First processing unit 51 outputs information indicating the identification result to a display unit (not shown), such as a display, provided in gas identification system 100. As a result, the identification result by first processing unit 51 is displayed on the display unit. First processing unit 51 may store the information indicating the identification result in storage unit 90. First processing unit 51 may also output the information indicating the identification result to an external device.

[0097] The second processing unit 52 performs information processing on the plurality of first signals based on the plurality of second signals before the first processing unit 51 performs the classification processing to improve the classification accuracy of the classification processing. For example, the second processing unit 52 performs correction processing on the plurality of first signals based on the plurality of second signals before the first processing unit 51 performs the classification processing. For example, as the correction processing on the plurality of first signals based on the plurality of second signals, the second processing unit 52 corrects the signal values ​​of each of the plurality of first signals or multiple feature amounts extracted from the plurality of first signals. Furthermore, the second processing unit 52 may select one or more first signals to be used in the classification processing from the plurality of first signals based on the plurality of second signals.

[0098] The processing by the signal processing unit 50 will be described in detail later.

[0099] The first acquisition unit 41, the second acquisition unit 42, the first processing unit 51, and the second processing unit 52 are realized by a microcomputer or a processor or the like that incorporates a program that performs the above-mentioned and later-described processes. The program may be stored in the storage unit 90. The first acquisition unit 41, the second acquisition unit 42, the first processing unit 51, and the second processing unit 52 may be realized by a single microcomputer or processor or the like, or may be realized by multiple microcomputers or processors or the like. The first acquisition unit 41, the second acquisition unit 42, the first processing unit 51, and the second processing unit 52 may each be realized by a dedicated logic circuit that performs the above-mentioned and later-described processes.

[0100] The storage unit 90 is a storage device that stores information and data necessary for processing performed by the identification device 102. The storage unit 90 is realized by, for example, a semiconductor memory or a hard disk drive (HDD).

[0101] The storage unit 90 stores the trained logical model used in the classification process by the first processing unit 51. The storage unit 90 may store information necessary for the second processing unit 52 to perform information processing.

[0102] The trained logical model is, for example, a trained logical model for identifying which type of molecule among multiple types of molecules is contained in sample gas. The trained logical model, for example, takes as input multiple feature quantities extracted from signals output from multiple gas sensors 10 including at least one gas sensor 10A, and outputs information indicating which type of molecule among multiple types of molecules is contained in sample gas. The trained logical model may take as input multiple feature quantities extracted from signals output from multiple gas sensors 10 including at least one gas sensor 10A, and output whether or not a specific molecule is contained in sample gas.

[0103] The trained logical model is constructed by performing machine learning on the logical model using, as training data, a known molecule to be identified and a plurality of feature quantities extracted from signals output from a plurality of gas sensors 10, including at least one gas sensor 10A exposed to a sample gas containing the known molecule to be identified. Examples of the logical model used in machine learning include a neural network, a random forest, a support vector machine, and a self-organizing map.

[0104] [Operation] Next, a description will be given of the operation of gas identification system 100 according to the present embodiment. The operation of gas identification system 100 can also be considered as processing in a gas identification method using multiple gas sensors 10.

[0105] FIG. 5 is a flowchart showing an example of the operation of gas identification system 100 according to the present embodiment.

[0106] 5 , first, the exposure unit 20 exposes the plurality of gas sensors 10 constituting the gas sensor group 15 to the sample gas under the control of the control unit 30 (step S11). For example, during a second period of the measurement period in which the plurality of gas sensors 10 constituting the gas sensor group 15 are exposed to the sample gas, the exposure unit 20 exposes the plurality of gas sensors 10 to the sample gas under conditions in which molecules contained in the sample gas are more likely to be adsorbed to the gas sensors 10 than during the first and third periods. Furthermore, the exposure unit 20 exposes the plurality of gas sensors 10 to the reference gas during the first and third periods. For example, the control unit 30 operates the intake pump 23 and controls the opening and closing of each port of the three-way solenoid valve 22, thereby exposing the plurality of gas sensors 10 to the reference gas during the first and third periods and exposing the plurality of gas sensors 10 to the sample gas during the second period.

[0107] Next, in step S11, the acquisition unit 40 acquires a plurality of signals output from the plurality of gas sensors 10 exposed to the sample gas during the measurement period. Specifically, the first acquisition unit 41 acquires a plurality of first signals corresponding to the electrical characteristic values ​​of the sensitive membranes 11 output from each gas sensor 10A belonging to the first gas sensor group 15A exposed to the sample gas in step S11 (step S12). The second acquisition unit 42 acquires a plurality of second signals corresponding to the electrical characteristic values ​​of the sensitive membranes 11 output from each gas sensor 10B belonging to the second gas sensor group 15B exposed to the sample gas in step S11 (step S13). Steps S12 and S13 may be performed in parallel, for example.

[0108] Fig. 6 is a diagram showing an example of a signal output from the gas sensor 10. Fig. 6 schematically shows an example of the change over time in the intensity (e.g., voltage) of a signal output from one of the gas sensors 10 during a measurement period Tm consisting of a first period T1, a second period T2, and a third period T3.

[0109] In step S11, for example, during the first period T1 and the third period T3 of the measurement period Tm, the three-way solenoid valve 22 is in the second state, and the exposure unit 20 exposes the plurality of gas sensors 10 to the reference gas. Also, during the second period T2 of the measurement period Tm, the three-way solenoid valve 22 is in the first state, and the exposure unit 20 exposes the plurality of gas sensors 10 to the sample gas. As a result, the plurality of gas sensors 10 are exposed to the reference gas only during the first period T1 and the third period T3 of the measurement period Tm, and the plurality of gas sensors 10 are exposed to the sample gas only during the second period T2 of the measurement period Tm. As a result, the signal from the gas sensor 10 acquired by the acquisition unit 40 changes, for example, as shown in FIG. 6 .

[0110] First, during the first period T1 during which the gas sensor 10 is exposed to the reference gas, the signal value barely changes. Next, during the second period T2 during which the gas sensor 10 is exposed to the sample gas, the sensitive film 11 of the gas sensor 10 adsorbs molecules to be identified in the sample gas, causing the signal value to fluctuate (e.g., increase). Then, during the third period T3 during which the gas sensor 10 is again exposed to the reference gas, the adsorbed molecules are released from the sensitive film 11 of the gas sensor 10, causing the signal value that fluctuated during the second period to return to the reference value. The reference value is, for example, the value before the signal value begins to fluctuate due to the exposure of the gas sensor 10 to the sample gas (i.e., the value immediately before the start of the second period T2 or the value at the end of the first period T1). In this way, a pulse-like signal is acquired by exposing the gas sensor 10 to the sample gas once. In the example shown in FIG. 6 , the signal output from the gas sensor 10 is a convex pulse, but it may also be a concave pulse. That is, in the example shown in FIG. 6, the base signal value before the gas sensor 10 is exposed to the sample gas is the lowest value VL, and the rising peak signal value is the highest value VH, but the base signal value before the gas sensor 10 is exposed to the sample gas may also be the highest value, and the falling peak signal value may also be the lowest value.

[0111] The lengths of the first period T1, the second period T2, and the third period T3 are not particularly limited and are set according to, for example, the configuration of the plurality of gas sensors 10 and the type of molecules to be identified.

[0112] Next, the second processing unit 52 performs a correction process on the plurality of first signals used in the identification process obtained in step S12, based on the plurality of second signals obtained in step S13 (step S14).

[0113] Because the concentration of molecules to be identified contained in the sample gas may vary within the storage unit 21, the concentration of the molecules to be identified contained in the sample gas may differ depending on the position of the gas sensor 10 within the storage unit 21. As a result, the effect of exposure to the sample gas on the output signal may vary depending on the position of the gas sensor 10. For example, when multiple gas sensors 10 are arranged in a planar layout as shown in FIG. 4 , the downstream gas sensor 10 receives sample gas in which some of the molecules to be identified contained in the sample gas have been adsorbed by the upstream gas sensor 10. In other words, the concentration of the molecules to be identified in the sample gas decreases toward the downstream side of the gas flow. Therefore, when the sample gas flows within the storage unit 21, the gas sensor 10 downstream in the gas flow is more likely to experience a smaller change in signal due to exposure to the sample gas than the gas sensor 10 upstream in the gas flow. The second processing unit 52 performs, for example, a correction process on the multiple first signals to cancel out the effect of the concentration distribution of the molecules to be identified. This improves the accuracy of the identification process using the multiple first signals in the subsequent identification process.

[0114] Here, a specific example of the correction process performed by the second processing unit 52 based on the plurality of second signals will be described. FIG. 7 is a diagram showing an example of the amount of change in the second signal output by the gas sensor 10B belonging to the second gas sensor group 15B arranged in the planar layout shown in FIG. 4. The amount of change in the signal output by the gas sensor 10B is, for example, the amount of change ΔV shown in FIG. 6, specifically, the difference (VH - VL) between the minimum value VL and the maximum value VH of the signal. The horizontal axis of FIG. 7 indicates the row in which the gas sensor 10B is arranged (see FIG. 4). The vertical axis of FIG. 7 indicates the amount of change in the second signal, normalized by setting the amount of change in the second signal output by the gas sensor 10B arranged in the first row to 1. FIG. 7 is based on the results of measurements of the second signal obtained by the inventors of the present application using a gas sensor group 15.

[0115] As shown in FIG. 7 , among the gas sensors 10B arranged in a row direction parallel to the flow direction of the sample gas, the gas sensors 10B located downstream in the gas flow exhibit smaller changes in the second signal. Because the sensitive films 11 of the gas sensors 10B have the same material composition and shape, they all have the same response characteristics to the same type of molecules. Therefore, the changes in the second signal correspond to the concentration of the target molecules in the sample gas in the flow direction of the sample gas. Therefore, the distribution of the concentration of the target molecules in the sample gas in the flow direction of the sample gas can be detected using the multiple second signals. Furthermore, the concentration of the target molecules in the sample gas can be considered to be the same in the column direction perpendicular to the flow direction of the sample gas. Therefore, the gas sensors 10 arranged in the column direction can be considered to be exposed to sample gas with the same concentration of the target molecules. Therefore, by correcting the first signal output by the gas sensor 10A belonging to the first gas sensor group 15A using the second signal output by the gas sensor 10B arranged in the same column, the influence of the distribution of the concentration of the target molecules can be canceled out. In this way, the second processing unit 52 performs correction processing on the plurality of first signals based on the plurality of second signals and the position of each gas sensor 10A belonging to the first gas sensor group 15A.

[0116] For example, the second processing unit 52 corrects the first signal output by the gas sensor 10A such that the smaller the change in the second signal output by the gas sensor 10B located in the same column, the greater the correction amount by which the signal value of the first signal output by the gas sensor 10A increases. Specifically, the second processing unit 52 calculates, as a correction parameter, the ratio of the change in the second signal output by the gas sensor 10B in each column to the change in the second signal output by the gas sensor 10B in the fourth column, which has the largest change in the second signal. The second processing unit 52 then corrects the first signals by dividing the signal value of the first signal output by the gas sensor 10A in each column by the ratio of the second signal output by the gas sensor 10B located in the same column. The second processing unit 52 may correct the signal value of the first signal for the entire measurement period, or may correct the signal value of the first signal for a portion of the measurement period (e.g., the second period or later). The correction parameter used in the correction process is not particularly limited. For example, the correction parameter may be a ratio of the amount of change in the second signal output by the gas sensor 10B in each column to a predetermined value. Alternatively, the correction parameter may be calculated based on the rate or speed of change of the second signal, rather than the amount of change in the second signal. Alternatively, the correction parameter may be a correction parameter that corrects the first signals by multiplying the signal values ​​of the first signals output by the gas sensor 10A in each column by the correction parameter.

[0117] Referring back to FIG. 5 , the first processing unit 51 then extracts multiple feature quantities from each of the multiple first signals corrected in step S14 (step S15). The feature quantities extracted for each first signal may be one or more. That is, one or more feature quantities are extracted from one first signal. The one or more feature quantities extracted from each first signal include, for example, at least one of the change amount, change rate, and slope of the first signal. Such feature quantities are susceptible to the influence of the interaction between the molecules and the gas sensor 10, and therefore can improve the accuracy of the identification process described below. Note that the types of feature quantities described above are merely examples, and the type of one or more feature quantities extracted from each first signal is not particularly limited. For example, the one or more feature quantities may include the signal value of the first signal at a certain point in time.

[0118] The gas sensors 10A have different sensitivity characteristics to the same type of molecules because the sensitive films 11 have different material compositions, and therefore output different first signals even when exposed to the same sample gas, allowing different feature quantities to be extracted.

[0119] In step S15, the first processing unit 51 may extract a feature from at least one of the plurality of second signals. This allows the second signal to also be used in the identification process, thereby improving the identification performance in the subsequent identification process. This can be particularly effective when the material composition of the sensitive membrane 11 of each gas sensor 10B belonging to the second gas sensor group 15B is different from the material composition of the sensitive membrane 11 of any of the gas sensors 10A belonging to the first gas sensor group 15A. For example, the first processing unit 51 selects one or more second signals from which to extract a feature based on the plurality of second signals. For example, the first processing unit 51 extracts a feature from the second signal with the largest signal change (the change ΔV in FIG. 4 ) among the plurality of second signals. The first processing unit 51 may extract a feature from the second signal with the change closest to the predetermined signal change, or may extract a feature from each of the plurality of second signals. The first processing unit 51 may use the amount of change in the second signal used in the correction process by the second processing unit 52 as the feature amount.

[0120] The feature quantities extracted from the second signal are the same as those extracted from the first signal. When the first processing unit 51 also extracts feature quantities from the second signal, the second processing unit 52 may also perform the correction process described in step S14 on the second signal from which feature quantities are extracted before step S15.

[0121] Next, the first processing unit 51 identifies molecules contained in the sample gas based on the plurality of feature quantities extracted in step S15 (step S16). For example, as an identification process, the first processing unit 51 inputs the plurality of feature quantities extracted in step S15 into the trained logical model stored in the storage unit 90, and the trained logical model outputs an identification result of the molecules contained in the sample gas.

[0122] In the above description, the second processing unit 52 corrects the signal values ​​of the first signals as the correction process for the first signals. However, this is not limiting. For example, the second processing unit 52 may correct multiple feature quantities extracted from the first signals. In this case, the order of steps S14 and S15 is reversed. In step S15, the first processing unit 51 extracts multiple feature quantities from the first signals that have not been subjected to correction processing. Then, in step S14, the second processing unit 52 performs correction processing on the multiple feature quantities extracted from the first signals based on the multiple second signals. For example, the second processing unit 52 extracts feature quantities of the same type as the multiple feature quantities extracted from the first signals from the second signals and calculates correction parameters using the feature quantities extracted from the multiple second signals. For example, if the feature quantities are signal changes, the second processing unit 52 applies the correction parameters described above with reference to FIG. 7 to the multiple feature quantities extracted from the first signals that have not been subjected to correction processing.

[0123] As described above, in the gas identification system 100, the gas sensors 10 constituting the gas sensor group 15 include a first gas sensor group 15A including a plurality of gas sensors 10A whose sensitive films 11 have different material compositions, and a second gas sensor group 15B including a plurality of gas sensors 10B whose sensitive films 11 have the same material composition. The signal processing unit 50 identifies molecules contained in the sample gas based on a plurality of first signals output from the gas sensors 10A belonging to the first gas sensor group 15A exposed to the sample gas and a plurality of second signals output from the gas sensors 10B belonging to the second gas sensor group 15B exposed to the sample gas.

[0124] As a result, because the gas sensors 10A belonging to the first gas sensor group 15A have different material compositions of the sensitive films 11, information regarding differences in molecular adsorption behavior due to differences in the material composition of the sensitive films 11 can be obtained from the multiple first signals and used to identify molecules contained in the sample gas. Furthermore, because the gas sensors 10B belonging to the second gas sensor group 15B have the same material composition of the sensitive films 11, differences in the multiple second signals output by the gas sensors 10B can be used to obtain information about the sample gas that is free of the influence of differences in the material composition of the sensitive films 11. For example, because the gas sensors 10B have the same composition and shape of the sensitive films 11, differences in the amount of change in the multiple second signals can be considered to represent differences in the concentration of molecules to be identified in the sample gas, thereby obtaining information about the concentration distribution of the molecules to be identified. As a result, for example, by correcting the multiple first signals using information about the concentration distribution of the molecules to be identified, the influence of the concentration distribution of molecules to be identified in the sample gas to which the gas sensor 10A is exposed on the identification can be reduced. Therefore, by using not only a plurality of first signals but also a plurality of second signals to identify molecules contained in the sample gas, gas identification system 100 can perform identification using different types of information, thereby improving the accuracy of the identification.

[0125] In addition, if there is no distribution in the concentration of the molecules to be identified contained in the sample gas, the differences between the multiple second signals can also be used to detect things other than the distribution of the concentration, such as the temperature of each gas sensor 10B.

[0126] [Another Example of Planar Layout of Gas Sensor Group] Next, a description will be given of another example of the planar layout of the plurality of gas sensors 10 constituting the gas sensor group 15. In the following description of the planar layout, differences from the above-described planar layout will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0127] For example, among the plurality of gas sensors 10, the gas sensor 10A may be disposed between the plurality of gas sensors 10B. FIG. 8 is a plan view showing a first example of a planar layout of the gas sensor group 15 according to this embodiment. In the example shown in FIG. 8, the plurality of gas sensors 10 constituting the gas sensor group 15 are arranged in a matrix of 3 rows and 8 columns. In the example shown in FIG. 8, as in the example shown in FIG. 4, the row direction is parallel to the direction of gas flow in the storage portion 21, and the column direction is perpendicular to the direction of gas flow in the storage portion 21. In the example shown in FIG. 8, the plurality of gas sensors 10B belonging to the second gas sensor group 15B are arranged along the row direction via at least one of the gas sensors 10A belonging to the first gas sensor group 15A. This allows the plurality of gas sensors 10B belonging to the second gas sensor group 15B to efficiently detect the concentration distribution of molecules to be identified contained in the sample gas, even when the number of gas sensors 10 is large, thereby reducing the number of gas sensors 10B. In the example shown in FIG. 8, the plurality of gas sensors 10B are arranged at equal intervals.

[0128] 8, for example, the same correction parameters as those used for the first signals output by the gas sensors 10A in a column adjacent to the column in which the gas sensor 10B is not arranged are used for the first signals output by the gas sensors 10A in that column. Furthermore, the correction parameters used for the first signals output by the gas sensors 10A in the column in which the gas sensor 10B is arranged may be supplemented with the correction parameters used for the first signals output by the gas sensors 10A in the column in which the gas sensor 10B is arranged.

[0129] In yet another example, the gas sensors 10B in the gas sensors 10 may be arranged not only in the row direction but also in the column direction. FIG. 9 is a plan view showing a second example of a planar layout of the gas sensor group 15 according to this embodiment. In the example shown in FIG. 9 , the gas sensors 10 constituting the gas sensor group 15 are arranged in a matrix of four rows and four columns. In the example shown in FIG. 9 , the direction of sample gas flow is not fixed because the configuration of the exposure portion 20 is different from that of the above example. In the example shown in FIG. 9 , the gas sensors 10B are arranged in predetermined rows and columns. This allows detection of a two-dimensional concentration distribution of molecules to be identified contained in the sample gas, and the detected concentration distribution can be used for correction processing of the first signals. Note that in the example shown in FIG. 9 , the gas sensors 10B are arranged in the first end row and the first end column in the row direction, but the gas sensors 10B may be arranged in any row and column. Furthermore, although the plurality of gas sensors 10B are arranged without any gas sensors 10A in between, at least one gas sensor 10A may be arranged between the gas sensors 10B in the arrangement direction.

[0130] In yet another example, the plurality of gas sensors 10B may be arranged two-dimensionally in a distributed manner among the plurality of gas sensors 10. Fig. 10 is a plan view showing another third example of the planar layout of the gas sensor group 15 according to this embodiment. In the example shown in Fig. 10, the plurality of gas sensors 10 constituting the gas sensor group 15 are arranged in a matrix of 8 rows and 8 columns. In the example shown in Fig. 10, the direction of flow of the sample gas is not fixed because the configuration of the exposure portion 20 is different from that of the above example, etc.

[0131] In the example shown in FIG. 10 , the multiple gas sensors 10 include multiple gas sensor sets 10s, each of which includes one or more gas sensors 10B and one or more gas sensors 10A arranged adjacent to one another. The multiple gas sensor sets 10s are arranged two-dimensionally. In FIG. 10 , each gas sensor set 10s is illustrated surrounded by a dashed rectangle. Specifically, in the gas sensor set 10s, one gas sensor 10B and three gas sensors 10A are arranged in a matrix of two rows and two columns. Furthermore, the arrangement of the one gas sensor 10B and the three gas sensors 10A is the same in each of the multiple gas sensor sets 10s. Furthermore, in the example shown in FIG. 10 , the multiple gas sensors 10B are arranged in two or more columns and two or more rows. This planar layout of the multiple gas sensors 10 allows detection of a two-dimensional concentration distribution of molecules to be identified in the sample gas, and this can be used for correcting the multiple first signals.

[0132] Next, an example of the operation of gas identification system 100 including a plurality of gas sensors 10 having the planar layout shown in Fig. 10 will be described. Fig. 11 is a flowchart showing another example of the operation of gas identification system 100 according to the present embodiment.

[0133] As shown in FIG. 11, from step S11 to step S13, the same operations as those in the example of operation described above with reference to FIG. 5 are performed.

[0134] Then, after step S13, the second processing unit 52 selects one or more first signals from the multiple first signals acquired in step S12 based on the multiple second signals acquired in step S13 (step S21).

[0135] Here, a specific example of the process in which the second processing unit 52 selects one or more first signals from the plurality of first signals based on the plurality of second signals will be described. Figures 12A to 12D are diagrams showing an example of the amount of change in the second signal output by the gas sensor 10B belonging to the second gas sensor group 15B arranged in the planar layout shown in Figure 10. Figures 12A, 12B, 12C, and 12D show the amount of change in the second signal output by the gas sensor 10B in the first row, first column, seventh row, and seventh column, respectively. In Figures 12A to 12D, the horizontal axis indicates the column or row in which the gas sensor 10B is arranged. In Figures 12A to 12D, the vertical axis indicates the amount of change in the second signal.

[0136] 12A to 12D , the change in the gas sensor 10B decreases toward the seventh column and toward the seventh row, resulting in a decrease in the concentration of the target molecule in the sample gas. The second processing unit 52 selects, from the plurality of first signals, a first signal output by a gas sensor 10A included in a gas sensor set 10s including a gas sensor 10B that outputs a second signal whose change in the second signal is equal to or greater than a predetermined threshold. For the second signal change shown in FIGS. 12A to 12D , the second processing unit 52 selects, from the plurality of first signals, a first signal output by a gas sensor 10A included in a gas sensor set 10s including the gas sensors 10B arranged in the first, third, first, and third columns. In other words, the first signal output by a gas sensor 10A located in the fifth or seventh row and the fifth or seventh column is not selected and is excluded. Note that the second processing unit 52 may select all of the first signals if the amount of change in all of the second signals is smaller than a predetermined threshold. Alternatively, the second processing unit 52 may determine not to perform correction processing on the first signals if the amount of change in all of the second signals is smaller than a predetermined threshold. In other words, if the amount of change in all of the second signals is smaller than a predetermined threshold, step S14 may not be performed.

[0137] Next, in steps S14 to S16, an operation is performed in which the multiple first signals used in the above-described operation example described with reference to Fig. 5 are replaced with one or more first signals selected in step S21. Therefore, the first processing unit 51 identifies molecules contained in the sample gas by performing an identification process using only the one or more first signals selected in step S21 from the multiple first signals acquired in step S12. This makes it possible to exclude from the first signals used in the identification process the first signals output by the gas sensor 10A in which the concentration of molecules to be identified in the exposed sample gas is low, thereby improving the identification accuracy.

[0138] In addition, in this operation example, in step S14, the second processing unit 52 corrects, for example, a first signal output by a gas sensor 10A belonging to the first gas sensor group 15A using a second signal output by a gas sensor 10B included in the same gas sensor set 10s as the gas sensor 10A.

[0139] Also in this operation example, in steps S14 to S16, one or more of the plurality of second signals may be further used in the identification process, as in the operation example described above with reference to Fig. 5. In this case, the first processing unit 51 extracts feature amounts from one or more second signals of the plurality of second signals whose amount of change is equal to or greater than a predetermined threshold, and uses the feature amounts in the identification process.

[0140] Note that one of step S14 and step S21 may be omitted in the exemplary operation shown in Fig. 11. Furthermore, the exemplary operation described using Fig. 11 may be performed in gas identification system 100 including a plurality of gas sensors 10 having the planar layout shown in any of Figs. 4, 8, and 9.

[0141] [Modifications] Next, modifications of the embodiment will be described. In the following description of the modifications, differences from the above embodiment will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0142] FIG. 13 is a plan view showing an example of the planar layout of a gas sensor group 16 according to this modified example. In FIG. 13, each of the gas sensors 10 constituting the gas sensor group 16 is schematically shown as a rectangle. The plan view shown in FIG. 13 is a plan view of the gas sensors 10 positioned on the same plane, viewed from the thickness direction of the sensitive film 11 of each of the gas sensors 10. For ease of distinction, the gas sensor 10A belonging to the first gas sensor group 15A and the gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B are marked with different patterns in FIG. This also applies to the plan views showing the planar layout of the gas sensor group 16 described below.

[0143] The gas identification system according to this modification has a configuration in which gas sensor group 15 of gas identification system 100 according to the embodiment is replaced with a gas sensor group 16. As shown in Fig. 13 , gas sensor group 16 differs from gas sensor group 15 according to the embodiment in that it includes a second gas sensor group 16B instead of second gas sensor group 15B.

[0144] The second gas sensor group 16B is composed of a plurality of gas sensors 10B1 to 10B3, which are another portion of the plurality of gas sensors 10. The plurality of gas sensors 10B1 to 10B3 constituting the second gas sensor group 16B are gas sensors that output signals for improving the discrimination performance when discriminating molecules contained in a sample gas. The material composition of the sensitive film 11 of each of the plurality of gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B is the same as each other. For example, the material composition of the sensitive film 11 of each of the plurality of gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B is different from the material composition of the sensitive film 11 of any of the gas sensors 10A belonging to the first gas sensor group 15A.

[0145] Furthermore, the shapes of the sensitive membranes 11 of the gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B are different from one another. In this modification, the gas sensors 10B1 to 10B3 are an example of gas sensors with non-identical shapes. This makes it possible to obtain information regarding differences in the response characteristics of the gas sensors 10B1 to 10B3 to the sample gas due to differences in the shapes of the sensitive membranes 11. Note that the second gas sensor group 16B may further include multiple gas sensors 10B whose sensitive membranes 11 have the same shape.

[0146] The gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B may have different thicknesses of the sensitive films 11. Furthermore, the thinner the film, the higher the sensitivity of the gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B. The gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B may have different areas of the sensitive films 11 in a plan view. In this case, the sensitive films 11 of the gas sensors 10B1 to 10B3 may have the same thickness.

[0147] As shown in Fig. 13 , the gas sensors 10 constituting the gas sensor group 16 are arranged, for example, in a matrix. In the example shown in Fig. 13 , the gas sensors 10 are arranged in rows and columns along mutually orthogonal row and column directions. In the example shown in Fig. 13 , the row direction is parallel to the direction in which gas flows in the storage portion 21, and the column direction is orthogonal to the direction in which gas flows in the storage portion 21. In the example shown in Fig. 13 , the gas sensors 10 are arranged in three rows and four columns, but the number and arrangement of the gas sensors 10 can be changed depending on the purpose.

[0148] The gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B are arranged in the column direction without any gas sensors 10A belonging to the first gas sensor group 15A intervening therebetween. In the row direction, gas sensors 10A are arranged in addition to the gas sensors 10B arranged in the column direction. As will be described in detail later, arranging the gas sensors 10B1 to 10B3 in the row direction perpendicular to the direction in which the sample gas flows through the storage section 21 allows the gas sensors 10B to accurately detect the concentration indicator of the target molecules contained in the sample gas. Furthermore, since the gas sensors 10B are arranged without any gas sensors 10A intervening therebetween, the detection accuracy of the concentration indicator can be improved. In the example shown in FIG. 13 , the gas sensors 10B1 to 10B3 are arranged in the fourth column, which is located most upstream in the gas flow direction. The gas sensors 10B1 to 10B3 may also be arranged in columns other than the fourth column.

[0149] Next, the second signals output by the gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B will be described. FIG. 14 is a diagram illustrating an example of the amount of change in the second signals output by the gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B arranged in the planar layout shown in FIG. 13 . The horizontal axis of FIG. 14 indicates the rows in which the gas sensors 10B1 to 10B3 are arranged (see FIG. 13 ). The vertical axis of FIG. 14 indicates the amount of change in the second signal, normalized by setting the amount of change in the second signal output by the gas sensor 10B3 arranged in the third row (the amount of change ΔV in FIG. 4 ) to 1. FIG. 14 also illustrates the amount of change in the second signal when the gas sensors 10B1 to 10B3 are exposed to a sample gas having a relatively high concentration of molecules to be identified (the “high concentration gas” in the diagram) and when the gas sensors 10B1 to 10B3 are exposed to a sample gas having a relatively low concentration of the molecules (the “low concentration gas” in the diagram). 14, the gas sensor 10B1 arranged in the first row has the thinnest thickness of the sensitive film 11, the gas sensor 10B3 arranged in the third row has the thickest thickness, and the gas sensor 10B2 arranged in the second row has a thickness intermediate between that of the gas sensor 10B1 and the gas sensor 10B3. The multiple gas sensors 10B1 to 10B3 are formed with the sensitive film 11 having different thicknesses at equal intervals. Furthermore, FIG. 14 is a graph based on the results of measurements of the second signal obtained by the inventors of the present application when a gas sensor group 16 was actually prepared.

[0150] 14, in the gas sensors 10B1 to 10B3 arranged in the first to third rows, the thinner the film thickness of the sensitive film 11, the larger the change in the second signal. As described above, it can be considered that the concentration of molecules to be identified in the sample gas is the same in the column direction perpendicular to the flow direction of the sample gas. Therefore, in the multiple gas sensors 10B1 to 10B3, the thinner the film thickness of the sensitive film 11, the higher the sensitivity.

[0151] Furthermore, as shown in FIG. 14 , the effect of the thickness of the sensitive film 11 on the change in the second signal varies depending on the concentration of the molecules to be identified in the sample gas. In the example shown in FIG. 14 , the effect of the thickness of the sensitive film 11 on the change in the second signal is greater when the concentration of the molecules to be identified in the sample gas is lower. Taking advantage of this, for example, the slope of the relationship between the thickness of the sensitive film 11 and the change in the second signal can be used as an indicator of the concentration of the molecules to be identified in the sample gas. Note that in FIG. 14 , the change in the second signal is smaller when the gas sensors 10B1 to 10B3 are exposed to a high-concentration gas than when they are exposed to a low-concentration gas. This is due to normalization. Before normalization, the change in the second signal is larger when the gas sensors 10B1 to 10B3 are exposed to a high-concentration gas than when they are exposed to a low-concentration gas.

[0152] For example, in the correction process in step S14, the second processing unit 52 calculates the slope of the relationship between the film thickness of the sensitive film 11 and the amount of change in the second signals based on the plurality of second signals, and performs correction processing on the plurality of first signals based on the calculated slope. For example, the second processing unit 52 performs correction such that the larger the calculated slope, the larger the correction amount for increasing the signal values ​​of the plurality of first signals or the feature quantities extracted from the plurality of first signals. This allows the magnitude of the first signals to be compensated for and used in the identification process even when the concentration of molecules to be identified in the sample gas introduced into the container 21 is low. Furthermore, when the first processing unit 51 extracts feature quantities from one or more of the plurality of second signals, the second signals from which feature quantities are extracted may be selected according to the slope.

[0153] The second signals are not limited to being used in the correction process, but may be used in the identification process by using information regarding the difference in response characteristics of the gas sensors 10B1 to 10B3 to the sample gas obtained from the second signals as a feature, etc. For example, the slope may be used as a feature in the identification process.

[0154] Next, a description will be given of another example of the planar layout of the plurality of gas sensors 10 that make up the gas sensor group 16. In the following description of the planar layout, differences from the above planar layout will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0155] For example, among the plurality of gas sensors 10, the gas sensor 10A may be disposed between the plurality of gas sensors 10B1 to 10B3. FIG. 15 is a plan view showing a first example of a planar layout of the gas sensor group 16 according to this modification. In the example shown in FIG. 15, the plurality of gas sensors 10 constituting the gas sensor group 16 are arranged in a matrix of six rows and four columns. In the example shown in FIG. 15, as in the example shown in FIG. 13, the row direction is parallel to the direction of gas flow in the storage portion 21, and the column direction is perpendicular to the direction of gas flow in the storage portion 21. In the example shown in FIG. 15, the plurality of gas sensors 10B1 to 10B3 belonging to the second gas sensor group 16B are arranged in the column direction via at least one of the gas sensors 10A belonging to the first gas sensor group 15A. This allows the number of the plurality of gas sensors 10B1 to 10B3 to be reduced even when the number of the plurality of gas sensors 10 is increased.

[0156] In yet another example, a plurality of sets of gas sensors 10 may be arranged, each set having a sensitive film 11 with different thicknesses. Fig. 16 is a plan view showing a second example of a planar layout of a gas sensor group 16 according to this modified example. In the example shown in Fig. 16, the gas sensors 10 constituting the gas sensor group 16 are arranged in a matrix of 8 rows and 8 columns. In the example shown in Fig. 16, the configuration of the exposure portion 20 is different from that of the above example, and the flow direction of the sample gas is not fixed.

[0157] In the example shown in FIG. 16 , the second gas sensor group 16B includes multiple non-identical-shaped gas sensor sets 10Bs each composed of multiple gas sensors 10B1 to 10B4, each having a different thickness of the sensitive film 11. In each non-identical-shaped gas sensor set 10Bs, for example, the multiple gas sensors 10B1 to 10B4 are arranged adjacent to one another. At least one of the gas sensors 10A belonging to the first gas sensor group 15A is arranged between the multiple non-identical-shaped gas sensor sets 10Bs. In FIG. 16 , each non-identical-shaped gas sensor set 10Bs is illustrated surrounded by a dashed rectangle. For example, the non-identical-shaped gas sensor sets 10Bs are arranged in a matrix so that the difference between the number of rows and the number of columns is minimized. In the example shown in FIG. 16 , the multiple gas sensors 10B1 to 10B4 are arranged in a matrix of two rows and two columns in each non-identical-shaped gas sensor set 10Bs. In addition, in the set 10Bs of gas sensors having different shapes, the arrangement of the gas sensors 10B1 to 10B4 is the same.

[0158] Each of the non-identical-shaped gas sensor sets 10Bs is disposed at an end in the row direction or an end in the column direction of the plurality of gas sensors 10. In the example shown in Fig. 16, the second gas sensor group 16B includes four non-identical-shaped gas sensor sets 10Bs, and the four non-identical-shaped gas sensor sets 10Bs are disposed at the four corners of the plurality of gas sensors 10 arranged in a matrix.

[0159] Because each of the non-uniformly shaped gas sensor sets 10Bs includes multiple gas sensors 10B1 to 10B4 with different thicknesses of the sensitive film 11, the multiple second signals can be used to detect an index of the concentration of molecules to be identified in the sample gas at the locations where each of the non-uniformly shaped gas sensor sets 10Bs is located. Therefore, the second gas sensor group 16B, which includes multiple non-uniformly shaped gas sensor sets 10Bs, can detect the concentration distribution of molecules to be identified in the sample gas. For example, as described above, the slope of the relationship between the thickness of the sensitive film 11 and the amount of change in the second signal can be used in the correction process for the multiple first signals as an index of the concentration at the locations where each of the non-uniformly shaped gas sensor sets 10Bs is located. For example, in the correction process in step S14, the second processing unit 52 performs the correction process for the multiple first signals based on the positional relationship between the multiple non-uniformly shaped gas sensor sets 10Bs and the gas sensor 10A and the slope of the relationship between the thickness of the sensitive film 11 and the amount of change in the second signal.

[0160] While the gas identification system and gas identification method according to the present disclosure have been described above based on embodiments and examples, the present disclosure is not limited to these embodiments and examples. Various modifications conceivable by those skilled in the art to the embodiments and examples, as well as other configurations constructed by combining some of the components of the embodiments and examples, are also included within the scope of the present disclosure, provided they do not deviate from the gist of the present disclosure.

[0161] For example, in the above embodiment, the second signals output by each gas sensor 10B belonging to the second gas sensor group 15B are used in the correction process for the first signals. However, this is not limited to this. For example, the correction process may not be performed by the second processing unit 52, and the first processing unit 51 may perform the identification process using feature amounts extracted from the first signals and feature amounts extracted from the second signals. In this case, the first processing unit 51 may further use information indicating the position of the gas sensor 10B in the second gas sensor group 15B in the identification process.

[0162] In the above embodiment, the acquisition unit 40 directly acquires the signals output from the gas sensors 10, but this is not limiting. For example, the acquisition unit 40 may acquire the first signals and the second signals output from the gas sensors 10 via a network. In this case, for example, the detection device 101 and the identification device 102 each include a communication circuit and communicate with each other via the network. This communication may be wireless or wired. Furthermore, the communication method (communication standard) for this communication is not particularly limited. Furthermore, this communication may be via a wide area communication network such as the Internet.

[0163] Furthermore, in the above-described embodiment, a process executed by a specific processing unit may be executed by another processing unit. Furthermore, the order of multiple processes may be changed, or multiple processes may be executed in parallel. The allocation of components included in gas identification system 100 to multiple devices is merely an example. A component included in one device (one of detection device 101 and identification device 102) may be included in another device (the other of detection device 101 and identification device 102). For example, a component included in one of detection device 101 and identification device 102 may be included in the other of detection device 101 and identification device 102. Furthermore, for example, gas identification system 100 may be implemented by a single device, or by three or more devices.

[0164] For example, the processes described in the above embodiments may be realized by centralized processing using a single device (system), or may be realized by distributed processing using multiple devices. Furthermore, the processor that executes the processes may be a single processor or multiple processors. That is, centralized processing or distributed processing may be performed.

[0165] Furthermore, for example, in the above-described embodiments, some or all of the components of the gas identification system according to the present disclosure may be configured with dedicated hardware, or may be implemented by executing a software program appropriate for each component. Each component may be implemented by a program execution unit, such as a CPU or processor, reading and executing a software program stored on a recording medium, such as a hard disk drive or semiconductor memory.

[0166] Additionally, components of a gas identification system according to the present disclosure may be configured with one or more electronic circuits, each of which may be a general-purpose circuit or a specialized circuit.

[0167] The one or more electronic circuits may include, for example, a semiconductor device, an integrated circuit (IC), or a large-scale integration (LSI). The IC or LSI may be integrated on a single chip or on multiple chips. Although the IC or LSI is referred to here as an IC or LSI, the name may vary depending on the degree of integration, and may be called a system LSI, a very large-scale integration (VLSI), or an ultra-large-scale integration (ULSI). A field programmable gate array (FPGA), which is programmed after the LSI is manufactured, can also be used for the same purpose.

[0168] Furthermore, the general or specific aspects of the present disclosure may be realized as a system, an apparatus, a method, an integrated circuit, or a computer program. Alternatively, the general or specific aspects may be realized as a computer-readable non-transitory recording medium such as an optical disk, a HDD, or a semiconductor memory on which the computer program is stored. Alternatively, the general or specific aspects of the present disclosure may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0169] For example, the present disclosure may be realized as a gas identification method executed by a computer included in a gas identification system, or as a program for causing a computer to execute such a gas identification method. Furthermore, the present disclosure may be realized as a computer-readable non-transitory recording medium having such a program recorded thereon, or as a program product including such a program.

[0170] The gas identification system and gas identification method disclosed herein are useful in systems for identifying molecules contained in sample gases, and can be used, for example, to identify various odor molecules from food, the human body, buildings, etc.

[0171] 10, 10A, 10B, 10B1, 10B2, 10B3, 10B4 Gas sensor 10Bs Non-identical shape gas sensor set 10s Gas sensor set 11 Sensitive film 12, 13 Electrode 14 Substrate 15, 16 Gas sensor group 15A First gas sensor group 15B, 16B Second gas sensor group 20 Exposure section 21 Storage section 22 Three-way solenoid valve 23 Intake pump 25a, 25b, 25c, 25d, 25e Piping 26a, 26b Intake port 26e Exhaust port 30 Control section 40 Acquisition section 41 First acquisition section 42 Second acquisition section 50 Signal processing section 51 First processing section 52 Second processing section 90 Memory section 100 Gas identification system 101 Detection device 102 Identification device P1, P2 Input port P3 Output port

Claims

1. A gas identification system comprising: a plurality of gas sensors each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong and a second gas sensor group to which some of the plurality of gas sensors belong; a first acquisition unit that acquires a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the first gas sensor group exposed to a sample gas; a second acquisition unit that acquires a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the second gas sensor group exposed to the sample gas; and a signal processing unit that identifies molecules contained in the sample gas based on the plurality of first signals acquired by the first acquisition unit and the plurality of second signals acquired by the second acquisition unit, wherein the material compositions of the sensitive films of the gas sensors belonging to the first gas sensor group are different from each other, and the material compositions of the sensitive films of the gas sensors belonging to the second gas sensor group are the same.

2. The gas identification system according to claim 1, wherein the second gas sensor group includes two or more identically shaped gas sensors, which are two or more gas sensors having the same shape of the sensitive membrane.

3. The gas identification system according to claim 2, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more identically shaped gas sensors are arranged along a predetermined direction without any gas sensors belonging to the first gas sensor group intervening therebetween.

4. The gas identification system according to claim 2, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more identically shaped gas sensors are arranged along a predetermined direction with at least one of the gas sensors belonging to the first gas sensor group interposed therebetween.

5. The gas identification system according to claim 3 or 4, further comprising a housing in which the plurality of gas sensors are disposed, and the predetermined direction is parallel to a direction in which the sample gas flows within the housing.

6. The gas identification system according to claim 2, wherein the plurality of gas sensors are arranged in a matrix, and the two or more identically shaped gas sensors are arranged in predetermined rows and predetermined columns.

7. The gas identification system according to claim 2, wherein the plurality of gas sensors includes a plurality of gas sensor sets in which one or more identically shaped gas sensors of the two or more identically shaped gas sensors and one or more gas sensors belonging to the first gas sensor group are arranged adjacent to each other, and the plurality of gas sensor sets are arranged two-dimensionally.

8. The gas identification system according to claim 1, wherein the second gas sensor group includes two or more non-identical shaped gas sensors, which are two or more gas sensors having sensitive films with different shapes.

9. The gas identification system according to claim 8, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more non-identically shaped gas sensors are arranged along a predetermined direction without any gas sensors belonging to the first gas sensor group intervening therebetween.

10. The gas identification system of claim 8, wherein the plurality of gas sensors are arranged two-dimensionally, and the two or more non-identically shaped gas sensors are arranged along a predetermined direction with at least one of the gas sensors belonging to the first gas sensor group interposed therebetween.

11. The gas identification system according to claim 9 or 10, further comprising a housing in which the plurality of gas sensors are disposed, and wherein the predetermined direction is perpendicular to a direction in which the sample gas flows within the housing.

12. The gas identification system of claim 8, wherein the plurality of gas sensors are arranged two-dimensionally, the second gas sensor group includes a plurality of non-identically shaped gas sensor sets in which the two or more non-identically shaped gas sensors are arranged adjacent to each other, and at least one of the gas sensors belonging to the first gas sensor group is arranged between the plurality of non-identically shaped gas sensor sets.

13. The gas identification system according to claim 8, wherein the two or more non-identical shaped gas sensors have sensitive films with different thicknesses, and the thinner the sensitive film, the higher the sensitivity.

14. The gas identification system according to any one of claims 1 to 4, 6 to 10, 12 and 13, wherein the number of gas sensors belonging to the first gas sensor group is equal to or greater than the number of gas sensors belonging to the second gas sensor group.

15. The gas identification system according to any one of claims 1 to 4, 6 to 10, 12 and 13, wherein the signal processing unit identifies molecules contained in the sample gas by performing an identification process using the plurality of first signals, and performs a correction process on the plurality of first signals based on the plurality of second signals before performing the identification process.

16. The gas identification system according to claim 15, wherein the material composition of the sensitive film of each gas sensor in the second gas sensor group is different from the material composition of the sensitive film of any gas sensor in the first gas sensor group.

17. The gas identification system of claim 16, wherein the signal processing unit further uses at least one second signal from among the plurality of second signals in the identification process.

18. The gas identification system according to claim 15, wherein the signal processing unit performs correction processing on the plurality of first signals based on the plurality of second signals and the positions of each gas sensor belonging to the first gas sensor group.

19. The gas identification system of any one of claims 1 to 4, 6 to 10, 12 and 13, wherein the signal processing unit selects one or more first signals from the plurality of first signals based on the plurality of second signals, and identifies molecules contained in the sample gas using only the one or more first signals among the plurality of first signals.

20. A gas identification method using a plurality of gas sensors, each having a sensitive film whose electrical characteristic value changes in response to molecular adsorption, the plurality of gas sensors including a first gas sensor group to which some of the plurality of gas sensors belong and a second gas sensor group to which some of the plurality of gas sensors belong, the method comprising: acquiring a plurality of first signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the first gas sensor group exposed to a sample gas; acquiring a plurality of second signals corresponding to the electrical characteristic values ​​output from each of the gas sensors belonging to the second gas sensor group exposed to the sample gas; identifying molecules contained in the sample gas based on the acquired first signals and second signals; the material composition of the sensitive film of each of the gas sensors belonging to the first gas sensor group is different from that of each of the gas sensors belonging to the second gas sensor group; and the material composition of the sensitive film of each of the gas sensors belonging to the second gas sensor group being the same.

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