Gas detection device

Abstract

To suppress deterioration of detection accuracy in a gas detection device including a plurality of sensitive elements.SOLUTION: The gas detection apparatus 1 includes a sensing portion 4, a substrate 5, and a flow channel 6. The electrical characteristic value of the sensing portion 4 changes in response to one or more types of molecules. The sensing portion 4 is disposed on the substrate 5. A gas to be supplied to the substrate 5 flows through the flow path 6. The sensing unit 4 includes a plurality of sensing elements Ax. The substrate 5 has a mounting surface on which the plurality of sensing elements Ax are arranged. The substrate 5 is disposed in the flow path 6 so that the gas flows along the placement surface. An internal space Sp1 including the substrate 5 in the flow path 6 and a plurality of streamlines SL in the internal space Sp1 are defined. Each of a plurality of lines representing the gas flow in the internal space Sp1 is referred to as a flow line SL. The plurality of sensitive elements Ax are arranged on the substrate 5 so that each of the streamlines SL passing through the sensitive elements Ax among the plurality of streamlines SL passes through only one sensitive element Ax.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a gas detection device, and more particularly to a gas detection device including a sensitive part whose electrical characteristic value changes in response to molecules. [Background technology]

[0002] Patent Document 1 discloses an air quality determination system. The air quality determination system includes a sensing unit, an exposure unit, a temperature control element, a control unit, an acquisition unit, a determination unit, and an output unit. The sensing unit changes its electrical characteristic value in response to one or more types of molecules. The exposure unit exposes the sensing unit to the sample gas for a predetermined measurement period. The temperature control element performs at least one of heating and cooling of the sensing unit. The acquisition unit acquires the electrical characteristic value of the sensing unit for the predetermined measurement period. The determination unit uses a trained model for determining the air quality state of the sample gas, and determines the air quality state of the sample gas based on the change in the electrical characteristic value. The output unit outputs the determination result of the determination unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 114158 Summary of the Invention [Problem to be solved by the invention]

[0004] In the air quality determination system (gas detection device) configured as described above, the sensitive part has a plurality of sensitive elements, and the plurality of sensitive elements are arranged side by side on the substrate.

[0005] However, when multiple sensor elements are arranged in the direction of the sample gas flow, the sample gas flowing over the substrate is adsorbed in order, starting with the sensor element on the windward side. This results in a dilution of the sample gas adsorbed by the sensor element on the downwind side. As a result, the reaction volume of the sensor element on the downwind side is smaller than that of the sensor element on the upwind side, reducing the detection accuracy of the sample gas.

[0006] An object of the present disclosure is to suppress a decrease in the detection accuracy of a sample gas in a gas detection device having multiple sensitive elements. [Means for solving the problem]

[0007] A gas detection device according to a first aspect of the present disclosure includes a sensitive part, a substrate, and a flow path. The sensitive part changes its electrical characteristic value in response to one or more types of molecules. The sensitive part is arranged on the substrate. A gas to be supplied to the substrate flows through the flow path. The sensitive part has a plurality of sensitive elements. The substrate has a mounting surface on which the plurality of sensitive elements are arranged. The substrate is arranged in the flow path so that the gas flows along the mounting surface. An internal space including the substrate is defined in the flow path, and a plurality of flow lines are defined in the internal space. Each of the plurality of lines representing the flow of the gas in the internal space is referred to as a streamline. The plurality of sensitive elements are arranged on the substrate so that each of the plurality of flow lines passing through a sensitive element passes through only one of the sensitive elements.

[0008] Also, a gas detection device according to a second aspect of the present disclosure includes a sensitive part, a substrate, and a flow path. The sensitive part changes an electrical characteristic value in response to one or more types of molecules. The sensitive part is arranged on the substrate. The flow path is for supplying gas to the substrate. The sensitive part has a plurality of sensitive elements. The substrate has a mounting surface on which the plurality of sensitive elements are arranged. The substrate is arranged in the flow path so that the gas flowing from upstream of the flow path in a direction normal to the mounting surface hits the plurality of sensitive elements. An internal space including the substrate is defined in the flow path, and a plurality of flow lines are defined in the internal space. Each of the plurality of lines representing the flow of the gas in the internal space is referred to as a streamline. The plurality of sensitive elements are arranged on the substrate so that each of the plurality of flow lines passing through a sensitive element passes through only one of the sensitive elements. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to suppress a decrease in the detection accuracy of a sample gas in a gas detection device having a plurality of sensitive elements. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of a main part of a gas detection device according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of a main part of the gas detection device. [Figure 3] FIG. 3 is a perspective view schematically showing a flow path of the gas detection device. [Figure 4] FIG. 4 is a cross-sectional view of an air quality evaluation system including the gas detection device. [Figure 5] FIG. 5 is a block diagram showing a schematic configuration of an air quality evaluation system including the gas detection device. [Figure 6] FIG. 6 is a schematic system configuration diagram of an air quality evaluation system including the gas detection device. [Figure 7] FIG. 7 is a schematic explanatory diagram showing the states before and after the sensitive part of the gas detection device absorbs molecules to be detected. [Figure 8] FIG. 8 is a schematic explanatory diagram showing a change in resistance value before and after the sensitive part absorbs molecules to be detected. [Figure 9] FIG. 9 is a cross-sectional view of a gas detection device according to a first modified example of the first embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view of a gas detection device according to a second modified example of the first embodiment of the present disclosure. [Figure 11] FIG. 11 is a cross-sectional view of a gas detection device according to a third modified example of the first embodiment of the present disclosure. [Figure 12] FIG. 12 is a cross-sectional view of a gas detection device according to a fourth modified example of the first embodiment of the present disclosure. [Figure 13] FIG. 13 is a perspective view schematically showing a flow path of a gas detection device according to a fifth modified example of the first embodiment of the present disclosure. [Figure 14]FIG. 14 is a perspective view schematically showing a flow path of a gas detection device according to a sixth modified example of the first embodiment of the present disclosure. [Figure 15] FIG. 15 is a perspective view schematically showing a flow path of a gas detection device according to a seventh modified example of the first embodiment of the present disclosure. [Figure 16] FIG. 16 is a cross-sectional view of a gas detection device according to the second embodiment of the present disclosure. [Figure 17] FIG. 17 is a perspective view schematically showing a flow path of the gas detection device. [Figure 18] FIG. 18 is a cross-sectional view of a gas detection device according to the third embodiment of the present disclosure. [Figure 19] FIG. 19 is a perspective view schematically showing a flow path of the gas detection device. [Figure 20] FIG. 20 is a cross-sectional view of a gas detection device according to a modified example of the third embodiment of the present disclosure. [Figure 21] FIG. 21 is a perspective view schematically showing a flow path of the gas detection device. DETAILED DESCRIPTION OF THE INVENTION

[0011] Gas detection devices according to embodiments will be described in detail below with reference to the drawings. However, the drawings described in the following embodiments are schematic diagrams, and the dimensional ratios of the sizes of the components and the like do not necessarily reflect the actual dimensional ratios. Furthermore, the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0012] In the following description, directions are defined as indicated by arrows such as "up," "down," "left," "right," "front," and "rear" in Figures 1 to 4. However, these directions are not intended to define the directions when the gas detection device is in use. Furthermore, the arrows indicating the directions in the drawings are merely shown for the purpose of explanation and have no substance.

[0013] (Embodiment 1) (1) Overview An overview of a gas detection device 1 according to a first embodiment will be described below with reference to FIGS.

[0014] The gas detector 1 of the first embodiment includes a sensitive part 4 , a substrate 5 , and a flow path 6 .

[0015] The sensitive part 4 changes its electrical characteristic value in response to one or more types of molecules to which it is sensitive. The sensitive part 4 has a plurality of sensitive elements Ax (x is a natural number).

[0016] In the first embodiment, as shown in FIGS. 2 and 3, the sensitive part 4 has three sensitive elements Ax, which are arranged side by side on the first surface 51 of the substrate 5. Hereinafter, the three sensitive elements Ax may be referred to as sensitive elements A1 to A3. The three sensitive elements A1 to A3 are arranged so as to be alternately shifted in the front-to-back direction. In the present disclosure, the "electrical characteristic value of the sensitive part 4" refers to, for example, electrical resistance, or a current value or voltage value corresponding to the electrical resistance. The number of sensitive elements Ax is not limited to three, and can be changed as long as it is two or more.

[0017] The sensitive part 4 is arranged on the substrate 5. The substrate 5 is arranged along the flow path 6. The substrate 5 is flat. The substrate 5 is square in plan view (see FIG. 2). The substrate 5 has a first surface 51 and a second surface 52 that face each other in the thickness direction (see FIG. 1). As will be described later, the substrate 5 is arranged in the flow path 6 so that gas (hereinafter, the gas to be detected will be referred to as sample gas) flows along the first surface 51. More specifically, the first surface 51 is the upper surface of the substrate 5, and the second surface 52 is the lower surface of the substrate 5. A plurality of sensitive elements Ax are arranged on the first surface 51. The first surface 51 corresponds to the "mounting surface for the plurality of sensitive elements Ax" in this disclosure. The second surface 52 faces the surface of the duct member that surrounds the flow path 6.

[0018] A sample gas to be supplied to the substrate 5 flows through the flow path 6. As shown in FIG. 1, an opening 171 for introducing gas into the flow path 6 is provided upstream of the flow path 6. An internal space Sp1 is formed as part of the flow path 6 and in which the substrate 5 is disposed. As shown in FIGS. 2 and 3, the internal space Sp1 is defined in the flow path 6. Here, the internal space Sp1 is a space in which the substrate 5 is present. The internal space Sp1 is a space in which the substrate 5 is present between a first flow path cross section CS1 and a second flow path cross section CS2. The first flow path cross section CS1 is a cross section of the flow path 6 defined on the upstream side of the substrate 5 in the flow path 6. The second flow path cross section CS2 is a cross section of the flow path 6 defined on the downstream side of the substrate 5 in the flow path 6. More specifically, the first flow path cross section CS1 is a rectangular surface perpendicular to the direction in which the gas passes. The second flow path cross section CS2 is a rectangular surface perpendicular to the direction in which the gas passes. The internal space Sp1 is a rectangular parallelepiped space extending in the front-to-rear direction. The internal space Sp1 may be any space that includes a part of the substrate 5 (more specifically, a part that includes at least the mounting surface of the plurality of sensitive elements Ax).

[0019] Arrows F in Figures 1 to 3 indicate the flow of sample gas. Hereinafter, the sample gas may be simply referred to as "gas." In embodiment 1, the sample gas enters the internal space Sp1 from the opening 171 (see Figure 1). The sample gas flows in the front-to-rear direction in the internal space Sp1, and in this embodiment, it flows from front to back (see Figures 2 and 3). The sample gas flows along the first surface 51 of the substrate 5. As the sample gas flows along the first surface 51 of the substrate 5, the multiple sensitive elements Ax arranged on the first surface 51 of the substrate 5 are exposed to the sample gas.

[0020] The sensitive element Ax is circular when viewed from above (see FIG. 2). More specifically, as will be described later, the sensitive element Ax has a disk shape, and its sides are covered with a resin material that is difficult for gas to pass through (see FIG. 7). In the first embodiment, "the sensitive element Ax is exposed to the sample gas" means that the sample gas flowing along the first surface 51 of the substrate 5 comes into contact with the upper surface of the sensitive element Ax, which has a disk shape.

[0021] More specifically, the sample gas flows in a direction parallel to the first surface 51 of the substrate 5. The first surface 51 being "parallel" to the flow direction of the sample gas does not necessarily mean that the first surface 51 on the same plane does not intersect with the gas flow direction, but may also mean that the first surface 51 on the same plane intersects with the gas flow direction at an angle of about several degrees. Note that "about several degrees" means that an error of, for example, plus or minus 10 degrees is acceptable.

[0022] In the first embodiment, a plurality of streamlines SL are defined in the internal space Sp1. Each of the plurality of lines representing the flow of gas in the internal space Sp1 is referred to as a streamline SL. The plurality of sensor elements Ax are arranged on the substrate 5 such that each of the plurality of streamlines SL that pass through the sensor element Ax passes through only one sensor element Ax.

[0023] A streamline SL is a curve drawn in the flow of sample gas in the internal space Sp1, and is a curve drawn so that the tangent at each point on the curve coincides with the direction of flow at that point. Therefore, in reality, there are countless streamlines SL representing the flow of gas in the internal space Sp1. Among the multiple streamlines SL, there are streamlines SL that do not pass through the sensor element Ax and streamlines SL that pass through the sensor element Ax. There can be multiple streamlines SL that pass through the sensor element Ax.

[0024] In the present disclosure, "the plurality of sensor elements Ax are arranged on the substrate 5 so that each of the plurality of sensor elements SL that pass through the sensor element Ax passes through only one sensor element Ax" means that the plurality of sensor elements Ax are arranged so that each of the plurality of sensor elements SL that pass through the sensor element Ax passes through one sensor element Ax. Note that although each sensor element SL passes through one sensor element Ax, each sensor element SL may pass through more than one sensor element Ax and may also pass through something other than the sensor element Ax in the internal space Sp1 (for example, the substrate 5).

[0025] 2 and 3, three streamlines SL are shown corresponding to the three sensor elements A1 to A3, respectively. In other words, only a representative streamline SL passing near the center of one sensor element Ax is shown.

[0026] The first streamline SL from the left passes through the sensor element A1 on the first surface 51 and also passes through a specific first point P11 on the first flow path cross section CS1 and a specific second point P21 on the second flow path cross section CS2. The second streamline SL from the left passes through the sensor element A2 on the first surface 51 and also passes through a specific first point P12 on the first flow path cross section CS1 and a specific second point P22 on the second flow path cross section CS2. The third streamline SL from the left passes through the sensor element A3 on the first surface 51 and also passes through a specific first point P13 on the first flow path cross section CS1 and a specific second point P23 on the second flow path cross section CS2.

[0027] In other words, each of the multiple streamlines SL is a line connecting a first point P1, one sensor element Ax corresponding to the streamline SL, and a second point P2. The first point P1 is a specific point in the flow path 6 where the gas flow flowing toward one sensor element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp1 where the gas flow that has passed through one sensor element Ax intersects with the second flow path cross section CS2.

[0028] In a steady flow, the streamline SL does not change over time, and the streamline SL and the trajectory (the path of the flow over time) coincide. Therefore, in a steady flow, if a tracer is continuously injected from a first point P1, which is a point in the gas flow in the internal space Sp1, the streamline SL that passes through one sensor element Ax and reaches a second point P2 can be visualized. One example of a tracer is to blow smoke into the airflow.

[0029] In contrast to the first embodiment, in the comparative example, multiple sensor elements Ax are considered to be arranged in a matrix on the substrate 5. When multiple sensor elements Ax are arranged in the flow direction of the sample gas, two or more sensor elements Ax exist for one flow line SL. As a result, the sample gas flowing over the substrate 5 is adsorbed in order from the sensor elements Ax on the upwind side, and the sample gas adsorbed on the sensor elements Ax on the downwind side becomes diluted. In the comparative example, variations occur in the amount of sample gas supplied to each of the multiple sensor elements Ax, reducing the detection accuracy of the sample gas.

[0030] On the other hand, in the gas detection device 1 of embodiment 1, as described above, the substrate 5 is arranged in the flow path 6 so that the sample gas flows along the mounting surface (first surface 51) of the multiple sensor elements Ax. When multiple flow lines SL passing through the multiple sensor elements Ax are defined, the multiple sensor elements Ax are arranged on the substrate 5 so that there is one sensor element Ax on each of the multiple flow lines SL. This makes it easier to uniformize the amount of sample gas supplied to the multiple sensor elements Ax. In other words, the gas detection device 1 of embodiment 1 can prevent a decrease in the detection accuracy of the sample gas.

[0031] Gas detection device 1 of embodiment 1 functions as part of air quality evaluation system 100 (see FIG. 5) when attached to device main body 2 (see FIG. 4). Air quality evaluation system 100 is used to detect, for example, odor molecules as detection target molecules. The detection target odor molecules may include, for example, volatile organic compounds (VOCs) contained in human body odor components, ammonia, etc.

[0032] The air quality evaluation system 100 detects VOCs, which are odor molecules contained in sample gases such as gases containing body odor collected from the body of a subject or exhaled breath, or air collected from a room in a building. Note that the molecules to be detected by the air quality evaluation system 100 are not limited to VOCs, and multiple types of odor molecules including VOCs may be detected.

[0033] The air quality evaluation system 100 can be used to evaluate the health status of a subject by using gas or exhaled breath containing body odor collected from the subject's body as a sample gas and evaluating the air quality of the sample gas. If the subject is a driver of a vehicle such as a car, train, airplane, or ship, the air quality evaluation system 100 may be used to evaluate the driver's fatigue level or alertness by evaluating the air quality of the sample gas. The air quality evaluation system 100 may also perform biometric authentication by evaluating the air quality of the sample gas collected from the subject. The air quality evaluation system 100 may also be used to search for rescue recipients trapped under rubble at disaster sites, etc., by detecting gas or exhaled breath containing body odor emitted by such recipients. The sample gas is not limited to gas (e.g., exhaled breath) emitted from the human body. The air quality evaluation system 100 may also be used to control the quality of food by detecting the presence or absence of gas emitted during food spoilage. The air quality evaluation system 100 may also evaluate the state of air quality in a room by detecting the presence or absence of VOCs emitted from building materials in the room, etc. The air quality evaluation system 100 may also evaluate the presence or absence of gases generated by fire, gases emitted from explosives or drugs, or toxic gases.

[0034] (2)Details The detailed configuration of gas detection device 1 according to embodiment 1 will be described below with reference to the drawings. Gas detection device 1 of embodiment 1 is a cartridge configured to be detachable from device main body 2. When gas detection device 1 is attached to device main body 2 (see FIG. 4), it functions as part of air quality evaluation system 100 (see FIG. 5).

[0035] (2-1) Air quality evaluation system As shown in FIG. 5, the air quality evaluation system 100 includes a gas detection device 1, a device main body 2, and an evaluation device 3. The evaluation device 3 evaluates the air quality state of the sample gas based on the change pattern of the electrical characteristic value of the sensor part 4 exposed to the sample gas. Note that, in the present disclosure, "evaluating the air quality state of the sample gas" may refer to determining whether or not target molecules are present in the sample gas. In other words, it may refer to evaluating whether or not target molecules exceed a predetermined concentration in the sample gas, or to evaluating the type of target molecules present in the sample gas. Furthermore, the number of target molecules is not limited to one type. When there are multiple types of target molecules, evaluating the air quality state may refer to evaluating the presence or absence and concentration of each type of molecule. Furthermore, evaluating the air quality state may refer to evaluating the odor quality of the sample gas (e.g., pleasant odor, unpleasant odor, etc.).

[0036] 5 and 6, the air quality evaluation system 100 of the first embodiment includes, in addition to the gas detection device 1 and the device main body 2, an evaluation device 3, which has the above-mentioned evaluation unit 312. A more detailed configuration of the evaluation unit 312 will be described in the section "(2-4) Evaluation device."

[0037] In the first embodiment, the device main body 2 and the evaluation device 3 are electrically connected via a wired cable CB1. The wired cable CB1 is a cable that can supply power and communicate.

[0038] (2-2) Gas detection device As shown in Figures 4 and 5, the gas detection device 1 of embodiment 1 includes a sensitive part 4, a substrate 5, a heater part 12, a temperature sensor 13, a connection terminal 14, a plurality of conductor parts 16, and a housing 17.

[0039] (substrate) As shown in Fig. 4, the substrate 5 is a flat member. More specifically, the substrate 5 is a printed wiring board having connection terminals 14, which are wiring patterns, and a plurality of conductor portions 16. The substrate 5 has a first surface 51 and a second surface 52 that face each other in the thickness direction. More specifically, the first surface 51 is the upper surface of the substrate 5, and the second surface 52 is the lower surface of the substrate 5.

[0040] Substrate 5 is configured to be detachably attached to connection portion 21 of device body 2. More specifically, gas detection device 1 is inserted into socket 27 of device body 2, and substrate 5 is inserted into connection portion 21, thereby attaching substrate 5 to device body 2. With substrate 5 inserted into connection portion 21, connection terminal 14 of substrate 5 is electrically connected to connection portion 21. Meanwhile, gas detection device 1 is removed from socket 27 of device body 2, and substrate 5 is removed from connection portion 21, thereby removing substrate 5 from device body 2. With substrate 5 attached to device body 2, gas detection device 1 of embodiment 1 is driven by power supplied to connection terminal 14 from power supply portion 34 of evaluation device 3 via device body 2.

[0041] (sensing part) As shown in FIG. 4, a sensitive part 4 is provided on the first surface 51 of the substrate 5. The sensitive part 4 changes its electrical characteristic value in response to one or more types of molecules to which it is sensitive. In the first embodiment, the sensitive part 4 has a plurality of sensitive elements Ax having different sensitivity characteristics from each other. The sensitive part 4 of the first embodiment is disposed in the internal space Sp1 of the housing 17.

[0042] 7, each of the multiple sensitive elements Ax is formed into a film shape having an organic composition 41 formed by molding an organic material into a disk shape and conductive particles 42 dispersed in the organic composition 41. When the sensitive element Ax is exposed to a sample gas containing molecules to be detected, the organic composition 41 absorbs the molecules to be detected and expands.

[0043] In the first embodiment, the side surface of the organic composition 41 is covered with a material (not shown) that is impermeable to the molecules to be detected. An example of this material is epoxy resin. Therefore, in the first embodiment, "the sensitive element Ax is exposed to a sample gas containing the molecules to be detected" means that the sample gas containing the molecules to be detected comes into contact with the circular upper surface of the disk-shaped organic composition 41.

[0044] 7, the diagram on the left shows the state before the sensor element Ax absorbs the target molecule M1, and the diagram on the right shows the state after the sensor element Ax absorbs the target molecule M1. When the sensor element Ax absorbs the target molecule M1, the organic composition 41 expands.

[0045] After the sensor element Ax absorbs the target molecule M1, the distance between the conductive particles 42 increases compared to before the sensor element Ax absorbed the target molecule M1, increasing the electrical resistance of the sensor element Ax. FIG. 8 is a graph showing the change in resistance of a certain sensor element Ax over time. As shown in FIG. 8, during the period from time t1 to time t2, the sensor element Ax absorbs molecules, causing the resistance of the sensor element Ax to increase by ΔR. In the first embodiment, the target molecules are odor molecules such as benzaldehyde, nonanal, and pyrrole. Specifically, the sensor element Ax contains an organic composition 41 that is sensitive to odor molecules. When the sensor element 4 is exposed to a sample gas containing odor molecules, the organic composition 41 absorbs the odor molecules, causing the sensor element Ax to expand, increasing the electrical resistance of the sensor element Ax.

[0046] On the other hand, when the sensitive part 4 is heated by the heat of the heater part 12 that heats the sensitive part 4, odor molecules are desorbed from the expanded organic composition 41, causing the organic composition 41 to shrink and the electrical resistance of the sensitive element Ax to decrease. After the sensitive element Ax desorbs the detection target molecule M1, the spacing between the conductive particles 42 becomes narrower than before the detection target molecule M1 was absorbed, and the electrical resistance of the sensitive element Ax decreases. As shown in Figure 8, during the period from time t2 to t3, the resistance value of the sensitive element Ax decreases by ΔR as the sensitive element Ax desorbs the molecule.

[0047] The sensitive element Ax has temperature dependency, whereby its electrical characteristic value (electrical resistance) changes depending on the temperature. Here, the sensitive element Ax includes a sensitive element Ax having a positive resistance coefficient (hereinafter also referred to as a positive characteristic sensitive element) Ax, where the electrical resistance increases with increasing temperature, and a sensitive element Ax having a negative resistance coefficient (hereinafter also referred to as a negative characteristic sensitive element) Ax, where the electrical resistance decreases with increasing temperature.

[0048] The heater control unit 241 of the device main body 2 controls the temperature of the sensor unit 4 by passing a pulsed current through the heater unit 12. By passing a pulsed current through the heater unit 12, the temperature of the sensor unit 4 is controlled according to a temperature change pattern in which a temperature rise period in which the temperature of the sensor unit 4 rises and a temperature fall period in which the temperature of the sensor unit 4 falls are alternately repeated. Here, in response to the temperature change in the sensor unit 4, the temperature of the internal space of the housing 17 also changes according to a temperature change pattern in which a temperature rise period in which the temperature rises and a temperature fall period in which the temperature falls are alternately repeated. The length of the temperature rise period is the time required for the desorption of odor molecules, and is, for example, several tens of seconds, but this time can be changed as appropriate. The length of the temperature fall period is the time required for the fluctuations in the electrical characteristic values ​​due to the adsorption of odor molecules to stabilize, and is, for example, several tens of seconds, but this time can be changed as appropriate.

[0049] (heater part) The heater unit 12 heats the sensor unit 4. More specifically, the heater unit 12 generates heat by passing a current through it under the control of a heater control unit 241 (described later) in the device main body 2, thereby heating the sensor unit 4. In the air quality evaluation system 100 of embodiment 1, the gas detection device 1 is provided with the heater unit 12, which allows the heater unit 12 to heat the sensor unit 4 more stably than in the air quality evaluation system of the comparative example in which the device main body is provided with a heater unit. As a result, the sensor unit 4 has the advantage of being able to stably desorb odor molecules. In other words, the evaluation unit 312 of the air quality evaluation system 100 has the advantage of being able to stably evaluate the air quality state of the sample gas. The heater unit 12 of embodiment 1 may be provided by printing an exothermic ink material on the first surface 51 of the substrate 5.

[0050] (Temperature sensor) The temperature sensor 13 is provided on the first surface 51 of the substrate 5 near the sensitive part 4. The temperature sensor 13 is a sensor for detecting the temperature of the sensitive part 4. In the first embodiment, the temperature of the sensitive part 4 is indirectly detected by detecting the temperature around the sensitive part 4. The temperature sensor 13 is, for example, a thermistor.

[0051] (Connection terminal, conductor part) The connection terminal 14 and the plurality of conductor portions 16 are wiring patterns (for example, patterns of copper foil, etc.) provided on the first surface 51 of the substrate 5. The connection terminal 14 is electrically connected to the connection portion 21 of the device body 2 when the substrate 5 is attached to the device body 2. As shown in FIG. 4, the connection terminal 14 is provided at the rear end of the first surface 51 of the substrate 5. More specifically, the connection terminal 14 is provided at a portion of the first surface 51 of the substrate 5 that is not housed in the housing 17. The connection terminal 14 has a plurality of electrodes aligned in the left-right direction.

[0052] Each of the plurality of conductors 16 is electrically connected to at least one of the plurality of electrodes in the connection terminal 14. Each of the plurality of sensitive elements Ax, heater section 12, and temperature sensor 13 in the sensitive section 4 corresponds one-to-one to a combination of two of the plurality of conductors 16, and is electrically connected to the corresponding two conductors 16.

[0053] That is, when the substrate 5 is attached to the device body 2, the sensitive part 4 is electrically connected to the connection part 21 of the device body 2 via the connection terminal 14 and the two corresponding conductor parts 16. Similarly, when the substrate 5 is attached to the device body 2, each of the heater part 12 and the temperature sensor 13 is electrically connected to the connection part 21 of the device body 2 via the connection terminal 14 and the two corresponding conductor parts 16.

[0054] (Storage part) As shown in FIG. 5 , the gas detection device 1 of the first embodiment further includes a storage unit 19 that stores characteristic data related to the sensitivity of the electrical characteristic value of the sensitive part 4. The storage unit 19 is a storage circuit that stores the characteristic data, such as a RAM, a ROM, or an EEPROM. In the present disclosure, the “sensing characteristic of the electrical characteristic value of the sensitive part 4” refers to the characteristic of the change pattern of the electrical characteristic value (electrical resistance) when each of the multiple sensitive elements Ax of the sensitive part 4 reacts to one or more types of molecules. In other words, the “characteristic data related to the sensitivity of the electrical characteristic value of the sensitive part 4” refers to data that indicates the characteristic of the change pattern of the electrical characteristic value when each of the multiple sensitive elements Ax of the sensitive part 4 reacts to one or more types of molecules. With the above configuration, the heater control unit 241 can control the power supplied to the heater unit 12 based on the characteristic data stored in the storage unit 19, i.e., the sensitivity of the electrical characteristic value of the sensitive part 4. As a result, the sensor 4 has the advantage of being able to desorb odor molecules based on the sensing characteristics of the electrical characteristic values ​​of the sensor 4. Furthermore, the acquisition unit 231 (described later) of the device main body 2 can acquire one cycle of pulse output from the multiple sensor elements Ax based on the sensing characteristics of the electrical characteristic values ​​of the sensor 4. As a result, the evaluation unit 312 of the air quality evaluation system 100 has the advantage of being able to evaluate the air quality state of the sample gas based on the sensing characteristics of the electrical characteristic values ​​of the sensor 4. Note that the memory unit 19 is omitted from Figure 4.

[0055] The characteristic data stored in the memory unit 19 includes data regarding the variation in the electrical characteristic values ​​of the sensor unit 4 under predetermined conditions. In this disclosure, "data regarding the variation in the electrical characteristic values ​​of the sensor unit 4 under predetermined conditions" refers to data indicating the estimated variation in the change pattern of the electrical characteristic values ​​(electrical resistance) under the predetermined conditions. The variation in the change pattern of the electrical characteristic values ​​refers to the variation in the change pattern of the electrical characteristic when each of the multiple sensor elements Ax of the sensor unit 4 reacts to one or more types of molecules. The "predetermined conditions" here refer to predetermined conditions, specifically, the temperature change pattern for controlling the temperature of the sensor unit 4 and the concentration of the sample gas to which the sensor unit 4 is exposed. With the above configuration, the heater control unit 241 can control the power supplied to the heater unit 12 based on the variation in the electrical characteristic values ​​of the sensor unit 4 under predetermined conditions. As a result, the sensor 4 has the advantage of being able to desorb odor molecules based on the variation in the electrical characteristic values ​​of the sensor 4 under predetermined conditions. Furthermore, the acquisition unit 231 (described later) of the device main body 2 can acquire one cycle of pulse output from the multiple sensor elements Ax based on the variation in the electrical characteristic values ​​of the sensor 4 under predetermined conditions. As a result, the evaluation unit 312 of the air quality evaluation system 100 has the advantage of being able to evaluate the air quality state of the sample gas based on the variation in the electrical characteristic values ​​of the sensor 4 under predetermined conditions.

[0056] (Housing) As shown in FIG. 4, the housing 17 accommodates the sensitive part 4 and at least a portion of the substrate 5. The housing 17 of the first embodiment accommodates a portion of the substrate 5 (a portion of the substrate 5 excluding the portion where the connection terminal 14 is provided), the sensitive part 4, the heater part 12, the temperature sensor 13, and the plurality of conductor parts 16. On the other hand, the housing 17 of the first embodiment does not accommodate the portion of the substrate 5 where the connection terminal 14 is provided. That is, in the first embodiment, the portion of the substrate 5, the sensitive part 4, the heater part 12, the temperature sensor 13, and the plurality of conductor parts 16 are accommodated in a main space MS of the housing 17 (see FIG. 4), and the connection terminal 14 is not accommodated in the main space MS of the housing 17. The main space MS is a space including the internal space Sp1 (see FIG. 1). The housing 17 of the first embodiment has a rectangular box shape. The housing 17 is made of a resin material, for example.

[0057] The housing 17 has an opening 171 at a position that does not overlap with the multiple sensor elements Ax when viewed in the thickness direction (vertical direction) of the substrate 5. The opening 171 is connected to the main space MS (see FIG. 4) of the housing 17. In other words, the main space MS (see FIG. 4) of the housing 17 is connected to the space outside the housing 17 via the opening 171. According to the above configuration, each of the multiple sensor elements Ax is exposed to the sample gas that enters the main space MS of the housing 17 from the opening 171 and is rectified in the main space MS. This has the advantage that the multiple sensor elements Ax can be uniformly exposed to the sample gas.

[0058] (2-3) Device body 5, the device main body 2 includes a housing 20, a connection unit 21, a fan 22, a processing unit 23, a control unit 24, and a communication unit 25. The device main body 2 of the first embodiment is driven by power supplied from the evaluation device 3 via a wired cable CB1.

[0059] The housing 20 accommodates the connection unit 21, the processing unit 23, the control unit 24, and the communication unit 25. The housing 20 has a hollow rectangular box shape, as shown in Fig. 6. The housing 20 is made of, for example, a resin material.

[0060] As shown in Figures 4 and 6, an opening 26 is provided on the top surface of the housing 20, and a fan 22 is disposed inside the opening 26. The opening 26 is connected to the storage space inside the housing 20. The storage space of the housing 20 is connected to the space outside the housing 20 via the opening 26. When the fan 22 operates (rotates), the sample gas flows into the internal space of the housing 20 through the opening 26. As shown in Figure 6, the opening 26 has a circular shape when viewed from above.

[0061] Furthermore, a socket 27 into which gas detection device 1 is inserted is provided on a side surface (front side surface) of housing 20. Socket 27 is connected to an accommodation space inside housing 20. As shown in Fig. 6, socket 27 has a rectangular shape in a side view.

[0062] 4 , housing 20 of embodiment 1 houses a part of housing 17 of gas detection device 1 when substrate 5 of gas detection device 1 is attached to device body 2. The state in which substrate 5 of gas detection device 1 is attached to device body 2 refers to the state in which gas detection device 1 is inserted into socket 27. More specifically, the part of housing 17 of gas detection device 1 is the part of housing 17 excluding the front end. In short, housing 20 of embodiment 1 houses sensitive unit 4 of gas detection device 1 when substrate 5 of gas detection device 1 is attached to device body 2. In other words, sensitive unit 4 of gas detection device 1 is disposed in the internal space of housing 20 of device body 2 when substrate 5 of gas detection device 1 is attached to device body 2.

[0063] The connection part 21 is configured to allow the board 5 to be attached and detached. The board 5 is attached to the connection part 21 by inserting the board 5 into the socket 27. On the other hand, the connection part 21 is detached from the board 5 by removing the inserted board 5 and pulling out the connection part 21 from the socket 27. The connection part 21 is electrically connected to each of the processing part 23 and the control part 24.

[0064] When the substrate 5 is attached (in a state where the substrate 5 is attached), the connection unit 21 is electrically connected to each of the sensitive unit 4, the heater unit 12, and the temperature sensor 13. More specifically, when the substrate 5 is attached, the connection unit 21 is electrically connected to an electrode of the connection terminal 14 of the gas detection device 1, and thereby electrically connected to each of the sensitive unit 4, the heater unit 12, and the temperature sensor 13 via the connection terminal 14 and the plurality of conductors 16. Therefore, when the substrate 5 is attached, the connection unit 21 electrically connects the sensitive unit 4 and the processing unit 23 (the acquisition unit 231). Furthermore, when the substrate 5 is attached, the connection unit 21 electrically connects each of the heater unit 12 and the temperature sensor 13 to the control unit 24 (the heater control unit 241). In other words, the connection unit 21 is an interface that connects the gas detection device 1 and the device main body 2. FIG. 4 schematically illustrates the connection unit 21.

[0065] Control unit 24 is a control circuit that controls the operations of gas detection device 1 and device main body 2. Control unit 24 can be realized, for example, by a computer system including one or more processors (microprocessors) and one or more memories. In other words, control unit 24 functions as control unit 24 when one or more processors execute one or more programs (applications) stored in one or more memories.

[0066] As shown in FIG. 5, the control unit 24 includes a heater control unit 241 and a fan control unit 242.

[0067] Heater control unit 241 controls the power flowing to heater unit 12 of gas detection device 1 based on the detection result of temperature sensor 13. More specifically, heater control unit 241 controls the power flowing to heater unit 12 of gas detection device 1 based on the temperature of sensitive unit 4 detected by temperature sensor 13.

[0068] The heater control unit 241 controls the power supplied to the heater unit 12 to change the temperature of the sensor unit 4 between a first temperature, which is the ambient temperature, and a second temperature, which is higher than the ambient temperature. The second temperature is set, for example, to a temperature approximately 7°C to 35°C higher than the first temperature. The difference between the first and second temperatures is preferably a temperature difference that allows adsorption and desorption of odor molecules to occur and minimizes changes in resistance value caused by temperature changes. Here, the difference between the first and second temperatures should be at least 7°C or more and 35°C or less. The difference between the first and second temperatures is preferably 20°C or more and 35°C or less, and more preferably 20°C or more and 25°C or less.

[0069] For example, when the first temperature is 25°C, the heater control unit 241 controls the temperature of the sensory unit 4 between the first temperature of 25°C and the second temperature of 50°C. When the first temperature is 0°C, the heater control unit 241 controls the temperature of the sensory unit 4 between the first temperature of 0°C and the second temperature of 25°C. When the first temperature is -20°C, the heater control unit 241 controls the temperature of the sensory unit 4 between the first temperature of -20°C and the second temperature of 5°C. The temperature change pattern used by the heater control unit 241 to change the temperature of the sensory unit 4 is not limited to the above-mentioned temperature change pattern. The heater control unit 241 may change the temperature of the sensory unit 4 in a temperature change pattern that results in greater fluctuations in the change pattern of the output of the sensory unit 4 depending on the air quality of the sample gas.

[0070] The heater control unit 241 of the first embodiment controls the power supplied to the heater unit 12 based on the characteristic data stored in the memory unit 19 of the gas detection device 1, i.e., the sensitivity characteristics of the electrical characteristic values ​​of the sensor unit 4. More specifically, the heater control unit 241 of the first embodiment sets the second temperature based on the sensitivity characteristics of the electrical characteristic values ​​of the sensor unit 4 so as to achieve a temperature difference that more reliably causes adsorption and desorption of odor molecules. The heater control unit 241 of the first embodiment controls the power supplied to the heater unit 12, thereby changing the temperature of the sensor unit 4 between a first temperature, which is the ambient temperature, and a second temperature set based on the sensitivity characteristics of the electrical characteristic values ​​of the sensor unit 4.

[0071] Fan control unit 242 controls the operation (rotation) of fan 22 by controlling the power flowing to fan 22. More specifically, fan control unit 242 controls whether or not to rotate fan 22, or the amount of rotation of fan 22. As an example, fan control unit 242 has a function of detecting whether or not gas detection device 1 is inserted into outlet 27, and may control fan 22 to rotate when it detects that gas detection device 1 has been inserted into outlet 27. On the other hand, fan control unit 242 may control fan 22 to stop when it detects that gas detection device 1 has been removed from outlet 27.

[0072] The processing unit 23 is a processing circuit that processes part of the operation of the air quality evaluation system 100. The processing unit 23 can be realized, for example, by a computer system including one or more processors (microprocessors) and one or more memories. In other words, the one or more processors function as the processing unit 23 by executing one or more programs (applications) stored in one or more memories.

[0073] As shown in FIG. 5 , the processing unit 23 includes an acquisition unit 231 and a calculation unit 232. The acquisition unit 231 acquires data on the temperature change pattern of the sensitive unit 4 detected by the temperature sensor 13 and pulse outputs of the multiple sensitive elements Ax for one cycle including one temperature rise period and one temperature fall period while the heater control unit 241 is causing a pulsed current to flow through the heater unit 12. A constant DC voltage is applied to each of the multiple sensitive elements Ax, and the acquisition unit 231 acquires changes in the electrical resistance of the multiple sensitive elements Ax as changes in the current flowing through the multiple sensitive elements Ax. Therefore, the pulse outputs are current signals whose magnitudes change depending on the electrical resistances of the multiple sensitive elements Ax. The acquisition unit 231 of the first embodiment acquires the pulse outputs of the multiple sensitive elements Ax for one cycle including one temperature rise period and one temperature fall period based on the characteristic data stored in the memory unit 19 of the gas detection device 1, i.e., the sensing characteristics of the electrical characteristic values ​​of the sensitive unit 4.

[0074] When the acquisition unit 231 acquires data on the temperature change pattern of the sensitive part 4 and one cycle of pulse outputs from the multiple sensor elements Ax, the calculation unit 232 calculates a pulse train in which the pulse outputs are connected in a predetermined order as multiple output data from the sensitive part 3. The multiple output data are patterns of change in electrical characteristic values. Since the multiple sensor elements Ax have different sensitivity characteristics to molecules to be detected, each of the multiple output data is a pulse train with a different pattern of change in electrical characteristic values.

[0075] The communication unit 25 is a communication module capable of wired communication with a communication unit 35 (described later) of the evaluation device 3. That is, the communication unit 25 of the first embodiment communicates with the communication unit 35 of the evaluation device 3 via a wired cable CB1. The communication unit 25 transmits a plurality of output data calculated by the calculation unit 232 to the communication unit 35.

[0076] (2-4) Evaluation device 5, the evaluation device 3 includes a processing unit 31, a storage unit 32, a display unit 33, a power supply unit 34, and a communication unit 35. The evaluation device 3 is, for example, a laptop or desktop personal computer, a smartphone, or a tablet terminal. In the present disclosure, the description will be given assuming that the evaluation device 3 is a laptop personal computer.

[0077] The memory unit 32 includes one or more storage devices. The storage device is, for example, a RAM, a ROM, or an EEPROM. The memory unit 32 stores a trained model 321 and the like used to evaluate the air quality state of the sample gas. The trained model 321 is a trained model that has learned the relationship between the change pattern in the output of the sensor unit 4 and the air quality state of the sample gas. The training data of the trained model is the change pattern in the output of the sensor unit 4 when the first condition and the second condition are changed, respectively. The first condition is a condition related to the gas to which the sensor unit 4 is exposed. The second condition is a condition related to the temperature change pattern that raises and lowers the temperature of the sensor unit 4. The trained model 321 may be generated by the air quality evaluation system 100, but it may also be generated by a learning system other than the air quality evaluation system 100.

[0078] The display unit 33 includes a display device such as a liquid crystal display. The display unit 33 displays the evaluation results input from the processing unit 31. For example, the display unit 33 displays the presence or absence of odor molecules in the sample gas, and if odor molecules are present, the amount of odor molecules, the quality of the odor, etc.

[0079] The processing unit 31 is a processing circuit that processes part of the operation of the air quality evaluation system 100. The processing unit 31 can be realized, for example, by a computer system including one or more processors (microprocessors) and one or more memories. In other words, the one or more processors execute one or more programs (applications) stored in one or more memories to function as the processing unit 31. Here, the programs are pre-recorded in the memory of the processing unit 31 or in the storage unit 32, but they may also be provided via a telecommunications line such as the Internet or by being recorded on a non-transitory recording medium such as a memory card.

[0080] As shown in FIG. 5, the processing unit 31 includes a learning unit 311 and an evaluation unit 312.

[0081] The learning unit 311 generates the trained model 321. In other words, the learning unit 311 is responsible for the training phase. The learning unit 311 accumulates the temperature change pattern data acquired by the acquisition unit 231 and the output data of the multiple sensing elements Ax as training data for generating the trained model 321. The learning unit 311 generates the trained model 321 using the collected training data. In other words, the learning unit 311 causes an artificial intelligence program to learn the relationship between the change patterns in the electrical characteristic values ​​of the multiple sensing elements Ax and the air quality state of the sample gas using the machine learning training data acquired by the air quality evaluation system 100. The artificial intelligence program is a machine learning model, and for example, a neural network, which is a type of hierarchical model, is used. The learning unit 311 generates the trained model 321 by having the neural network perform machine learning (e.g., deep learning) using the training data, and stores the trained model 321 in the memory unit 32. In addition, the learning unit 311 may improve the performance of the trained model 321 by performing re-training using training data newly collected by the acquisition unit 231 after the trained model 321 is generated.

[0082] The evaluation unit 312 is responsible for the so-called inference phase. Using the trained model 321 stored in the memory unit 32, the evaluation unit 312 evaluates the state of air quality of the sample gas based on the output data calculated by the calculation unit 232. Specifically, the evaluation unit 312 inputs the electrical characteristic values ​​of the sensor unit 4 in a state in which the heater control unit 241 controls the heater unit 12 so that the temperature of the sensor unit 4 exposed to the sample gas changes according to a temperature change pattern into the trained model 321. This allows the state of air quality of the sample gas to be evaluated. Here, in the first embodiment, the sensor unit 4 includes multiple sensor elements Ax. Therefore, the evaluation unit 312 evaluates the state of air quality of the sample gas based on the change pattern in the electrical characteristics of the multiple sensor elements Ax in a state in which the temperature of the multiple sensor elements Ax exposed to the sample gas is changed according to the above-mentioned temperature change pattern. Furthermore, the evaluation unit 312 inputs the measurement data of the temperature change pattern by the temperature sensor 13 acquired by the acquisition unit 231 and the output data calculated by the calculation unit 232 into the trained model 321. The trained model 321 performs inference based on the output data when the temperature of the sensor 4 changes according to the above-mentioned temperature change pattern, and evaluates the state of the air quality of the sample gas.

[0083] In the first embodiment, the evaluation unit 312 evaluates the air quality of the sample gas by determining whether or not odor molecules are present in the sample gas, and whether the amount of odor molecules contained in the sample gas is equal to or greater than a threshold. If the evaluation unit 312 determines that the sample gas contains odor molecules, it may further evaluate the concentration of the odor molecules in the sample gas.

[0084] It should be noted that it is not essential for the air quality evaluation system 100 to include the learning unit 311, and the evaluation unit 312 may perform the inference phase using a trained model 321 generated by an external computer system.

[0085] The evaluation unit 312 outputs the evaluation result to the display unit 33, thereby displaying the evaluation result of the evaluation unit 312 on the display unit 33. Note that the output of the evaluation result by the evaluation unit 312 is not limited to displaying it on the display unit 33, and the evaluation result, such as the presence or absence of odor molecules, may be output as sound using a buzzer or speaker.

[0086] Power supply unit 34 supplies power to device body 2 via wired cable CB1. Furthermore, when substrate 5 is attached to device body 2, power supply unit 34 supplies power to gas detection device 1 via device body 2. If evaluation device 3 includes a battery that stores power to drive evaluation device 3, power stored in the battery is supplied to device body 2 or gas detection device 1. Furthermore, if evaluation device 3 is supplied with power to drive evaluation device 3 from an external power source, it may supply power supplied from the external power source to device body 2 or gas detection device 1.

[0087] The communication unit 35 is a communication module capable of wired communication with the communication unit 25 of the device body 2. That is, the communication unit 35 of the first embodiment communicates with the communication unit 25 of the device body 2 via a wired cable CB1. The communication unit 35 receives a plurality of output data transmitted by the communication unit 25 and outputs the received output data to the processing unit 31.

[0088] (3) Effects In the gas detection device 1 according to the first embodiment, as shown in FIGS. 2 and 3, the substrate 5 is disposed in the flow path 6 so that the sample gas flows along the mounting surface (first surface 51) of the plurality of sensitive elements (Ax). A plurality of flow lines SL are defined in the internal space Sp1 of the flow path 6, which includes the substrate 5. At this time, the plurality of sensitive elements Ax are disposed on the substrate 5 so that one sensitive element Ax is present on each of the plurality of flow lines SL. This makes it easier to uniformize the amount of sample gas supplied to the plurality of sensitive elements Ax in the flow path 6. In other words, the gas detection device 1 according to the first embodiment can prevent a decrease in the detection accuracy of the sample gas.

[0089] 2 and 3, in the gas detection device 1 according to the first embodiment, the internal space Sp1 is a space including the substrate 5 between the first flow path cross section CS1 and the second flow path cross section CS2. Each of the plurality of flow lines SL is a line connecting a first point P1 and a second point P2. The first point P1 is a specific point in the flow path 6 where the flow of gas that enters the internal space Sp1 and flows toward one sensory element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp1 where the flow of gas that has passed through one sensory element Ax intersects with the second flow path cross section CS2. This makes it easier to identify the flow lines SL in the flow path 6.

[0090] The gas detection device 1 according to the first embodiment further includes a housing 17. As shown in FIG. 4, the housing 17 has an opening 171 at a position that does not overlap with the multiple sensor elements Ax when viewed in the thickness direction of the substrate 5 (the vertical direction in FIG. 4). This allows each of the multiple sensor elements Ax to be exposed to the sample gas that enters the main space MS of the housing 17 through the opening 171 and is rectified in the main space MS. This allows each of the multiple sensor elements Ax to be uniformly exposed to the sample gas. This makes it easier to prevent a decrease in the detection accuracy of the sample gas.

[0091] In the gas detection device 1 according to the first embodiment, the multiple sensitive elements Ax have different sensing characteristics from one another, which makes it possible to detect gases containing a greater variety of molecules, improving the detection accuracy of the sample gas.

[0092] (4) Modification of the first embodiment The above-described first embodiment is merely one of various embodiments of the present disclosure. Various modifications to the first embodiment are possible depending on the design and the like, as long as the object of the present disclosure can be achieved.

[0093] The following modifications may be implemented in appropriate combination. The same components as those in the above-described first embodiment are denoted by the same reference numerals and will not be described again. Arrows F in Figures 9 to 15 indicate the flow of sample gas.

[0094] (4-1) First Modification As shown in FIG. 9, in a gas detection apparatus 1A according to a first modification of the first embodiment, a plurality of sensitive elements Ax may be arranged in a line.

[0095] The detailed configuration of gas detection apparatus 1A according to the first modified example will be described below.

[0096] The substrate 5A of the first modified example is disposed in the internal space Sp1 and is similar to the substrate 5 of the first embodiment in that it has a flat plate shape, but the shape when viewed from above is different. The substrate 5 of the first embodiment has a square shape when viewed from above (see FIG. 2), but the substrate 5A has a rectangular shape when viewed from above. The length of the substrate 5A in the direction of gas flow through the flow path 6A (front-to-back direction in FIG. 9) is shorter than that of the substrate 5. On the other hand, the length of the substrate 5A in the width direction of the flow path 6A (left-to-right direction in FIG. 9) is longer than that of the substrate 5.

[0097] The sensitive section 4 has 14 sensitive elements Ax. The 14 sensitive elements Ax are arranged on the first surface 51 of the substrate 5A. The 14 sensitive elements Ax are arranged in a row in the longitudinal direction of the substrate 5A (the left-right direction in FIG. 9). In the first embodiment, the number of sensitive elements Ax is three, whereas in the first modified example, the number of sensitive elements Ax is 14. Increasing the number of sensitive elements Ax improves the detection accuracy of the gas detection device 1A.

[0098] A plurality of streamlines SL are defined in the internal space Sp1. Each of the plurality of lines representing the flow of gas in the internal space Sp1 is referred to as a streamline SL. A plurality of sensor elements Ax are arranged on the substrate 5A so that each of the plurality of streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax.

[0099] 9, only a representative flow line SL passing near the center of one sensor element Ax is shown, and three flow lines SL are shown corresponding to the three sensor elements Ax, respectively.

[0100] According to the gas detection device 1A of the first modified example, the amount of sample gas supplied to the 14 sensor elements Ax in the flow path 6A can be made uniform, so that the first modified example can also achieve the same effects as those of the above-mentioned embodiment 1.

[0101] (4-2) Second and third modified examples As shown in FIG. 10, in a gas detection apparatus 1B according to a second modification of the first embodiment, a plurality of sensitive elements Ax may be arranged in a staggered pattern.

[0102] The detailed configuration of gas detection apparatus 1B of the second modified example will be described below.

[0103] The substrate 5B of the second variant is arranged in the internal space Sp1, is flat, and has a rectangular shape when viewed from above, similar to the substrate 5A of the first variant, but the length of the substrate 5B in the short direction (front-to-back direction in Figure 10) is longer than that of the substrate 5A.

[0104] In the second modified example, the 14 sensitive elements Ax are arranged side by side in the longitudinal direction of the substrate 5B (the left-right direction in FIG. 10), but two adjacent sensitive elements Ax are arranged shifted in the front-rear direction.

[0105] A plurality of streamlines SL are defined in the internal space Sp1. Each of the plurality of lines representing the flow of gas in the internal space Sp1 is referred to as a streamline SL. A plurality of sensor elements Ax are arranged on the substrate 5B so that each of the plurality of streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax. In FIG. 10, only a representative streamline SL that passes near the center of one sensor element Ax is shown. Three streamlines SL are shown corresponding to each of the three sensor elements Ax.

[0106] According to the gas detection device 1B of the second modified example, the amount of sample gas supplied to the 14 sensor elements Ax in the flow path 6B can be made uniform, so that the second modified example can also achieve the same effects as those of the first embodiment.

[0107] However, if multiple sensor elements Ax are arranged in a row in the longitudinal direction of the substrate A, as in the first modified example, the aspect ratio of the substrate increases, making it difficult to process the substrate. In contrast, in the second modified example, two adjacent sensor elements Ax are arranged with a shift in the front-to-back direction, so that the length of the substrate 5B in the longitudinal direction (left-to-right direction in Figure 10) can be made shorter than that of the substrate 5A. Also, in the second modified example, the length of the substrate 5B in the lateral direction (front-to-back direction in Figure 10) can be made longer than that of the substrate 5A. This makes it possible to suppress an increase in the aspect ratio of the substrate.

[0108] Furthermore, if the spacing between adjacent sensitive elements Ax is too close, the adjacent sensitive elements Ax are more likely to come into contact with each other during manufacturing, which can reduce the yield of the sensitive unit 4. In the second modified example, the adjacent sensitive elements Ax are arranged with a shift in the front-to-back direction, which can increase the spacing between the adjacent sensitive elements Ax compared to the first modified example. This makes it easier to manufacture multiple sensitive elements Ax.

[0109] The multiple sensitive elements Ax may be arranged as shown in a third modified example in Fig. 11, as long as at least two adjacent sensitive elements Ax are arranged with a shift in the front-to-rear direction. Fig. 11 is a cross-sectional view of a gas detection device 1C according to a third modified example of embodiment 1. In the third modified example, 14 sensitive elements Ax are arranged on the substrate 5C in the longitudinal direction of the substrate 5C (the left-to-right direction in Fig. 11), but every two elements are arranged with a shift in the direction of gas flow in the flow path 6C (the front-to-rear direction in Fig. 11). Even with this type of arrangement, the same effect as in the second modified example can be obtained.

[0110] (4-3) Fourth Modification In the first embodiment and the first to third modified examples, the shapes of the substrates 5, 5A, 5B, and 5C are rectangular in plan view, but are not limited to this. As long as the substrate has a mounting surface on which a plurality of sensitive elements Ax can be arranged, the shape of the substrate may be, for example, circular or elliptical.

[0111] As shown in FIG. 12, in a gas detector 1D according to a fourth modification of the first embodiment, a substrate 5D may have a semi-doughnut shape in plan view.

[0112] The detailed configuration of gas detection apparatus 1D according to the fourth modified example of embodiment 1 will be described below.

[0113] In the fourth modified example, the sensitive unit 4 has ten sensitive elements Ax. The ten sensitive elements Ax are arranged on the first surface 51 of the substrate 5D. The ten sensitive elements Ax are arranged in a semicircular row in a plan view.

[0114] A plurality of streamlines SL are defined in the internal space Sp1 of the fourth modified example. Each of the plurality of lines representing the flow of gas in the internal space Sp1 is referred to as a streamline SL. A plurality of sensor elements Ax are arranged on the substrate 5B so that each of the plurality of streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax.

[0115] 12, only a representative flow line SL passing near the center of one sensor element Ax is shown, and four flow lines SL are shown corresponding to the four sensor elements Ax, respectively.

[0116] According to the gas detection device 1D of the fourth modified example, the amount of sample gas supplied to the ten sensor elements Ax can be made uniform in the flow path 6D, and therefore the fourth modified example can also achieve the same effects as those of the first embodiment.

[0117] (4-4) Fifth Modification In the first embodiment and the first to fourth modified examples, the flow paths 6, 6A to 6D are shaped like rectangular parallelepipeds, and the multiple sensitive elements Ax are arranged on one plane, but this is not limiting.

[0118] As shown in FIG. 13, in a gas detection apparatus 1E according to a fifth modification of the first embodiment, a flow path 6E is cylindrical.

[0119] The detailed configuration of gas detection apparatus 1E according to the fifth modified example will be described below.

[0120] In the fifth modified example, the internal space Sp2 is the space inside a cylindrical pipe material (e.g., a round pipe) that forms the flow path 6E. More specifically, the internal space Sp2 is the space that includes the substrate 5E between the circular first flow path cross section CS1 and the circular second flow path cross section CS2.

[0121] The substrate 5E is disposed on the inner surface of a cylindrical duct material that forms the flow path 6E. The substrate 5E is cylindrical, and the first surface 51 is the inner curved surface of the cylindrical substrate 5E. The substrate 5E may be a flexible substrate, and may be attached to the inner surface of the cylindrical duct material that forms the flow path 6E with the first surface 51, on which multiple sensor elements Ax are mounted, facing inward.

[0122] The sensitive section 4 has a plurality of sensitive elements Ax. The plurality of sensitive elements Ax are arranged three-dimensionally in a cylindrical flow path 6E. More specifically, ten sensitive elements Ax are arranged on a first surface 51 of a cylindrical substrate 5E that surrounds the flow path 6E. This increases the degree of freedom in designing the arrangement of the plurality of sensitive elements Ax and the structure of the flow path 6E. According to the fifth modification, the gas detection device 1E can be made smaller.

[0123] A plurality of streamlines SL are defined in the cylindrical internal space Sp2 of the fifth modified example. Each of the plurality of lines representing the flow of gas in the internal space Sp2 is referred to as a streamline SL. A plurality of sensor elements Ax are arranged on the substrate 5E such that each of the plurality of streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax.

[0124] 13 shows only a representative flow line SL passing near the center of one sensor element Ax. Since multiple sensor elements Ax are arranged on the substrate 5E so that each of the multiple flow lines SL has only one sensor element Ax, the amount of sample gas supplied to the multiple sensor elements Ax in the flow path 6E can be made uniform. This allows the fifth modified example to achieve the same effects as those of the first embodiment.

[0125] 13 is a line connecting a first point P1, a sensory element Ax, and a second point P2. The first point P1 is a specific point in the flow path 6E where the gas flow that enters the internal space Sp2 and flows toward the sensory element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp1 where the gas flow that has passed through the sensory element Ax intersects with the second flow path cross section CS2. This makes it easier to identify the flow line SL in a steady flow.

[0126] In the fifth modified example, ten sensor elements Ax were arranged on the first surface 51 of the cylindrical substrate 5E surrounding the flow path 6E, but this is not limiting as long as multiple sensor elements Ax are arranged three-dimensionally in the flow path 6E. "Multiple sensor elements Ax are arranged three-dimensionally" refers to a state in which multiple sensor elements Ax are not arranged on a single plane. For example, multiple sensor elements Ax may be arranged on multiple different surfaces, or multiple sensor elements Ax may be arranged on a curved surface.

[0127] (4-5) Sixth Modification In the first embodiment and the first to fifth modified examples, the substrates 5, 5A to 5E are each made of a single member, but this is not limiting.

[0128] As shown in FIG. 14, in a gas detection apparatus 1F according to a sixth modification of the first embodiment, a substrate 5F may include a plurality of sub-substrates 7 in a flow path 6F.

[0129] The detailed configuration of the gas detection apparatus 1F according to the sixth modified example of the first embodiment will be described below.

[0130] In the sixth modified example, the substrate 5F is divided into four sub-substrates 7. Each of the four sub-substrates 7 is flat and rectangular in plan view. Each of the four sub-substrates 7 is arranged along the inner circumferential surface of the rectangular parallelepiped flow path 6F. More specifically, the four sub-substrates 7 are arranged on the upper, lower, right, and left inner surfaces of the piping material that forms the flow path 6F, respectively.

[0131] The internal space Sp1 of the sixth modified example is the space inside the rectangular tubular pipe material, as in the first embodiment (see FIG. 3). More specifically, the internal space Sp1 is the space including the substrate 5F between the rectangular first flow path cross section CS1 and the rectangular second flow path cross section CS2 in the flow path 6F.

[0132] One sensor element Ax is arranged on each of the four sub-substrates 7. The multiple sensor elements Ax are arranged three-dimensionally in the flow path 6F. The four sensor elements Ax face the flow path 6F. In the sixth modified example, multiple streamlines SL are defined in the internal space Sp1. Each of the multiple lines representing the flow of gas in the internal space Sp1 is referred to as a streamline SL. Four sensor elements Ax are arranged on each of the four sub-substrates 7 so that each of the multiple streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax.

[0133] 14, only a representative flow line SL passing near the center of one sensor element Ax is shown. One flow line SL is shown corresponding to one sensor element Ax.

[0134] The streamline SL shown in Figure 14 is a line connecting a first point P1, a sensor element Ax corresponding to the streamline SL, and a second point P2. The first point P1 is a specific point in the flow path 6F where the gas flow that enters the internal space Sp1 and flows toward the sensor element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp1 where the gas flow that has passed through one sensor element Ax intersects with the second flow path cross section CS2. As a result, the sixth modified example can also achieve the same effects as those of the first embodiment.

[0135] Furthermore, according to the sixth modification, the substrate 5F is divided into four sub-substrates 7, so that it is possible to prevent a decrease in productivity due to an increase in the aspect ratio of the substrate.

[0136] 14, one sensitive element Ax is arranged on each of the multiple sub-substrates 7, but two or more sensitive elements Ax may be arranged on each of the multiple sub-substrates 7. By arranging at least one sensitive element Ax on each of the multiple sub-substrates 7, the degree of freedom in designing the arrangement of the multiple sensitive elements Ax and the structure of the flow path 6F is increased.

[0137] (4-6) Seventh Modification In the first embodiment and the first to sixth modified examples, the flow paths 6, 6A to 6F are each configured as a single flow path, but this is not limiting.

[0138] As shown in FIG. 15, in a gas detection apparatus 1G according to a seventh modification of the first embodiment, a flow path 6G may include a plurality of branch flow paths 8.

[0139] The detailed configuration of gas detection apparatus 1G of the seventh modified example will be described below.

[0140] The internal space Sp1 of the seventh modified example is a rectangular parallelepiped space defined by a rectangular parallelepiped flow path 6G, similar to the first embodiment (see FIG. 3). More specifically, the internal space Sp1 is a space including the substrate 5G between a rectangular first flow path cross section CS1 and a rectangular second flow path cross section CS2.

[0141] The plurality of branch flow paths 8 branches the flow of gas flowing in the flow path 6G. The flow path 6G includes four branch flow paths 8. More specifically, each of the four branch flow paths 8 is made of a cylindrical pipe material. Each of the four branch flow paths 8 extends in the traveling direction of the gas flowing through the flow path 6G (the front-to-rear direction in FIG. 15 ).

[0142] In the internal space Sp1, a substrate 5G is arranged so as to penetrate the bottom plates of the pipe materials that form the four branch flow paths 8 in the width direction of the flow path 6G (the left-right direction in FIG. 15).

[0143] In the seventh modified example, the sensitive unit 4 has four sensitive elements Ax. The four sensitive elements Ax are arranged on the first surface 51 of the substrate 5G. The four sensitive elements Ax are arranged in a row in the longitudinal direction of the substrate 5G (the left-right direction in FIG. 15). More specifically, the four sensitive elements Ax are arranged on the substrate 5G so that there is one sensitive element Ax for each of the four branch flow paths 8. This makes it possible to uniformize the amount of sample gas supplied to the multiple sensitive elements Ax in the flow path 6G, so that the seventh modified example can also achieve the same effects as those of the first embodiment.

[0144] 15 shows only a representative flow line SL passing near the center of one sensor element Ax. The flow line SL shown in FIG. 15 is a line connecting a first point P1, the sensor element Ax, and a second point P2. The first point P1 is a specific point in the flow path 6G where the gas flow that enters the internal space Sp1 and flows toward the sensor element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp1 where the gas flow that has passed through one sensor element Ax arranged on the substrate 5G in one branch flow path 8 intersects with the second flow path cross section CS2.

[0145] Since each of the branch flow paths 8 is cylindrical, it is possible to prevent the sample gas flowing through each branch flow path 8 from diffusing upward and to the left and right. This allows the sample gas to be supplied uniformly to each of the multiple sensor elements Ax. Furthermore, design freedom is increased because there is no need to consider the diffusion of the sample gas.

[0146] Each of the branched flow paths 8 is cylindrical and extends in the front-rear direction, but as long as it is capable of branching the gas flow in the flow path 6G, it may be a wall provided on the left and right, or a guide that guides the sample gas to each of the sensing elements Ax. This makes it possible to prevent the gas from diffusing in the left-right direction.

[0147] (Embodiment 2) Next, a gas detection device 1H according to a second embodiment of the present disclosure will be described with reference to the drawings. The same components as those in the first embodiment will be assigned the same reference numerals and description thereof will be omitted.

[0148] In the first embodiment, the substrate 5 was arranged in the flow path 6 so that the sample gas flowed along the first surface 51 of the substrate 5 (see, for example, FIG. 1). In contrast, in the gas detection device 1H of the second embodiment, as shown in FIG. 16, the substrate 5H is arranged in the flow path 6H so that the gas flowing from upstream of the flow path 6H along the normal direction to the first surface 51 of the substrate 5H strikes the multiple sensor elements Ax. In the present disclosure, "gas flows along the normal direction to the first surface 51 of the substrate 5H" does not necessarily mean that the first surface 51, which is on the same plane, intersects with the gas flow direction at a right angle, but may also mean that the first surface 51, which is on the same plane, and the gas flow direction are offset by several degrees from 90 degrees. Note that "several degrees" means that an error of, for example, plus or minus 10 degrees is acceptable.

[0149] As shown in FIG. 16, gas is introduced into the flow path 6H from an opening 171H provided in the upper part. As shown in FIGS. 16 and 17, an internal space Sp3 is defined in the flow path 6H. In this case, the internal space Sp3 is a space including the substrate 5H. The internal space Sp3 is a space defined between a first flow path cross section CS1, a second flow path cross section CS2, and a third flow path cross section CS3. The first flow path cross section CS1 is defined on the upstream side of the substrate 5H (upper in the figure) in the flow path 6H. The second flow path cross section CS2 is defined on the downstream side of the substrate 5H (forward in the figure) in the flow path 6H. The third flow path cross section CS3 is defined on the downstream side of the substrate 5H (rear in the figure) in the flow path 6H. More specifically, the first flow path cross section CS1 is rectangular. The second flow path cross section CS2 is rectangular. The third flow path cross section CS3 is rectangular.

[0150] The internal space Sp3 is a rectangular parallelepiped space extending in the front-to-rear direction. The sample gas that passes through the upper opening 171H of the flow path 6H enters the internal space Sp3 from the first flow path cross section CS1. The sample gas that passes through the first flow path cross section CS1 flows downward and collides with the first surface 51 of the substrate 5H arranged at the bottom of the flow path 6H. The sample gas then branches into a forward flow and a backward flow on the first surface 51. The sample gas that branches forward then flows along the first surface 51 of the substrate 5H and reaches the second flow path cross section CS2. Meanwhile, the sample gas that branches backward flows along the first surface 51 of the substrate 5H and reaches the third flow path cross section CS3. In this way, the multiple sensor elements Ax arranged on the first surface 51 of the substrate 5H are exposed to the sample gas.

[0151] In the second embodiment, the multiple sensitive elements Ax are arranged to surround the center of the first surface 51 of the substrate 5H. More specifically, as shown in Fig. 17, the sensitive unit 4 has four sensitive elements Ax, and the four sensitive elements Ax are arranged side by side on the first surface 51 of the substrate 5H. The four sensitive elements A1 to A4 are arranged side by side in two rows and two columns on the flat substrate 5H. Hereinafter, each of the four sensitive elements Ax may also be referred to as a sensitive element A1 to A4.

[0152] A plurality of streamlines SL are defined in the internal space Sp3. Each of the plurality of lines representing the flow of gas in the internal space Sp3 is referred to as a streamline SL. A plurality of sensor elements Ax are arranged on the substrate 5H so that each of the plurality of streamlines SL that pass through a sensor element Ax passes through only one sensor element Ax.

[0153] 17, only a representative flow line SL passing near the center of one of the sensor elements A1 to A4 is shown. Four flow lines SL are shown corresponding to the four sensor elements A1 to A4, respectively.

[0154] The first streamline SL from the left in the front is a line that passes through a specific first point P11 on the first flow path cross section CS1, the sensor element A3 on the first surface 51, and a specific second point P21 on the second flow path cross section CS2.

[0155] The second streamline SL from the left in the front is a line that passes through a specific first point P12 on the first flow path cross section CS1, the sensor element A4 on the first surface 51, and a specific second point P22 on the second flow path cross section CS2.

[0156] The first streamline SL from the left at the rear is a line that passes through a specific first point P11 on the first flow path cross section CS1, the sensor element A1 on the first surface 51, and a specific third point P31 on the third flow path cross section CS3.

[0157] The second streamline SL from the left at the rear is a line passing through a specific first point P12 on the first flow path cross section CS1, the sensor element A2 on the first surface 51, and a specific third point P32 on the third flow path cross section CS3.

[0158] In other words, each of the multiple streamlines SL is a line connecting a first point P1, a corresponding sensor element Ax, and a second point P2, or a line connecting a first point P1, a corresponding sensor element Ax, and a third point P3. The first point P1 is a specific point in the flow path 6H where the gas flow that enters the internal space Sp3 and flows toward the corresponding sensor element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp3 where the gas flow that has passed through the sensor element A3 or the sensor element A4 intersects with the second flow path cross section CS2. The third point P3 is a specific point in the internal space Sp3 where the gas flow that has passed through the sensor element A1 or the sensor element A2 intersects with the third flow path cross section CS3.

[0159] In contrast to the second embodiment, in the comparative example, multiple sensor elements Ax are arranged in a matrix on a substrate 5. In the comparative example, when sample gas is supplied from directly above the substrate, the sample gas flows from the center toward the periphery of the substrate. In this case, the sample gas flowing over the substrate is adsorbed in order from the sensor elements Ax on the central side, and the sample gas adsorbed on the sensor elements Ax on the periphery becomes diluted. In the comparative example, the amount of sample gas supplied to each of the multiple sensor elements Ax varies, reducing the detection accuracy of the sample gas.

[0160] On the other hand, in the gas detection device 1H of embodiment 2, as described above, the substrate 5H is arranged so that gas flowing from the upstream of the flow path 6H in the direction normal to the first surface 51 of the substrate 5H impinges on the multiple sensor elements Ax. A plurality of streamlines SL are defined to represent the flow of gas contacting the multiple sensor elements Ax in the internal space Sp3 including the substrate 5H. The multiple sensor elements Ax are arranged on the substrate 5H so that each of the multiple streamlines SL passes through one sensor element Ax. This makes it easier to uniformize the amount of sample gas supplied to the multiple sensor elements Ax. In other words, the gas detection device 1H of embodiment 2 can prevent a decrease in the detection accuracy of the sample gas.

[0161] (Embodiment 3) Next, a gas detection device 1i according to a third embodiment of the present disclosure will be described with reference to the drawings. The same components as those in the second embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0162] In the gas detection device 1i of embodiment 3, as shown in Figure 18, the substrate 5i is arranged so that gas flowing from upstream of the flow path 6i along the normal direction of the first surface 51 of the substrate 5i hits multiple sensitive elements Ax, as in embodiment 2 (see Figure 16).

[0163] In contrast, gas detection device 1i of embodiment 3 differs from embodiment 2 in that substrate 5i has ventilation holes 9 penetrating through substrate 5i in the thickness direction, and flow lines SL pass through ventilation holes 9, as shown in FIG.

[0164] As shown in FIG. 18, gas is introduced into the flow path 6i from an opening 171i provided in the upper part. As shown in FIGS. 18 and 19, an internal space Sp4 is defined in the flow path 6i. Here, the internal space Sp4 is a space including the substrate 5i in the flow path 6i. The internal space Sp4 is a space defined between a first flow path cross section CS1 and a second flow path cross section CS2. The first flow path cross section CS1 is defined on the upstream side of the substrate 5i in the flow path 6i (upper in the figure). The second flow path cross section CS2 is defined on the downstream side of the substrate 5i in the flow path 6i (lower in the figure). More specifically, the first flow path cross section CS1 is rectangular. The second flow path cross section CS2 is rectangular.

[0165] The internal space Sp4 is a rectangular parallelepiped space extending vertically. The sample gas flows vertically through the internal space Sp4. More specifically, the sample gas passes through the upper opening 171i of the flow path 6i and enters the internal space Sp4 from the first flow path cross section CS1. The sample gas then flows downward through the internal space Sp4 toward the first surface 51 of the substrate 5i. The flow of the sample gas then falls into three main cases. The first case is when the sample gas passes directly through the vent hole 9 of the substrate 5i and reaches the second flow path cross section CS2. The second case is when the sample gas collides with the first surface 51 of the substrate 5i, then passes through the vent hole 9 and reaches the second flow path cross section CS2. The third case is when the sample gas passes through the sensor element Ax on the first surface of the substrate 5i, then passes through the vent hole 9 and reaches the second flow path cross section CS2. In the third case, a plurality of sensitive elements Ax arranged on the first surface 51 of the substrate 5i are exposed to the sample gas.

[0166] In the third embodiment, as shown in Fig. 19, the sensitive unit 4 has four sensitive elements Ax, which are arranged side by side on the first surface 51 of the substrate 5i. The four sensitive elements A1 to A4 are arranged side by side in two rows and two columns on the flat substrate 5i. Hereinafter, the four sensitive elements Ax may also be referred to as the sensitive elements A1 to A4.

[0167] A plurality of ventilation holes 9 are provided in the substrate 5i. More specifically, the plurality of ventilation holes 9 are provided in the substrate 5i so as to surround each of the plurality of sensitive elements Ax. In the third embodiment, as shown in Fig. 19, nine ventilation holes 9 are provided in the substrate 5i. The nine ventilation holes 9 are arranged in three rows and three columns on the flat substrate 5i.

[0168] A plurality of streamlines SL are defined in the internal space Sp4. Each of the plurality of lines representing the flow of gas in the internal space Sp4 is referred to as a streamline SL. In the third embodiment, the plurality of streamlines SL pass through the ventilation holes 9 of the substrate 5i. A plurality of sensitive elements Ax are arranged on the substrate 5i such that each of the plurality of streamlines SL that pass through the sensitive element Ax passes through only one sensitive element Ax.

[0169] FIG. 19 shows only a representative streamline SL passing near the center of the sensor element A1. After passing through the sensor element A2 on the first surface 51 of the internal space Sp4, the single streamline SL branches into four directions. More specifically, the single streamline SL branches to the rear right, rear left, front right, and front left of the sensor element A2. The four branched streamlines SL then pass through the air vents 9 located to the rear right, rear left, front right, and front left of the sensor element A2, respectively. The four branched streamlines SL then travel downward and reach the second flow path cross section CS2.

[0170] The streamline SL that branches off to the rear right is a line that passes through a specific first point P1 on the first flow path cross section CS1, the sensor element A2 on the first surface 51, the air hole 9 to the rear right of the sensor element A2, and a specific second point P21 on the second flow path cross section CS2.

[0171] The streamline SL that branches off to the rear left is a line that passes through the sensory element A2 on the first surface 51, and also passes through the air vent 9 to the rear left of the sensory element A2, a specific first point P1 on the first flow path cross section CS1, and a specific second point P22 on the second flow path cross section CS2.

[0172] The streamline SL that branches off to the right and front is a line that passes through the sensory element A2 on the first surface 51, and also passes through the air vent 9 to the right and front of the sensory element A2, a specific first point P1 on the first flow path cross section CS1, and a specific second point P23 (not shown in Figure 19) on the second flow path cross section CS2.

[0173] The streamline SL that branches off to the left and front is a line that passes through the sensory element A2 on the first surface 51, and also passes through the air vent 9 to the left and front of the sensory element A2, a specific first point P1 on the first flow path cross section CS1, and a specific second point P24 (not shown in Figure 19) on the second flow path cross section CS2.

[0174] In other words, each of the multiple streamlines SL is a line connecting a first point P1 and a second point P2. The first point P1 is a specific point in the flow path 6 where the gas flow that enters the internal space Sp4 and flows toward one sensory element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp4 where the gas flow that has passed through one sensory element Ax and the vent hole 9 intersects with the second flow path cross section CS2.

[0175] In the gas detection device 1i according to the third embodiment, as described above, the substrate 5i is arranged so that gas flowing from upstream of the flow path 6i in the normal direction to the first surface 51 of the substrate 5i (the surface on which the multiple sensor elements Ax are mounted) impinges on the multiple sensor elements Ax. In the internal space Sp4 including the substrate 5i, multiple gas flow lines SL are defined. The multiple sensor elements Ax are arranged on the substrate 5i so that each of the multiple flow lines SL that pass through a sensor element Ax passes through only one sensor element Ax. This makes it easier to uniformize the amount of sample gas supplied to the multiple sensor elements Ax. In other words, the gas detection device 1i according to the third embodiment can prevent a decrease in the detection accuracy of the sample gas.

[0176] Furthermore, in gas detector 1i according to the third embodiment, substrate 5i has vent hole 9, so that the cross section of flow path 6i can be effectively utilized, thereby enabling gas detector 1i to be made smaller.

[0177] (Modification of the third embodiment) The above-described third embodiment is merely one of various embodiments of the present disclosure. The third embodiment can be modified in various ways depending on the design and the like as long as the object of the present disclosure can be achieved.

[0178] In the gas detection device 1J according to a modified example of embodiment 3, as shown in FIG. 20, the flow line SL passes through the ventilation hole 9J of the substrate 5J, and the gas flowing along the normal direction of the first surface 51 of the substrate 5J strikes multiple sensing elements Ax, which are the same as those in embodiment 3.

[0179] This modification differs from embodiment 3 in that a plurality of sensitive elements Ax are arranged on the underside of the substrate 5J in the flow path 6J, and gas that has passed through the ventilation holes 9J of the substrate 5J hits the plurality of sensitive elements Ax on the underside of the substrate 5J. Therefore, in this modification, the first surface 51, which is the mounting surface for the plurality of sensitive elements Ax, is the underside of the substrate 5J, and the second surface 52 is the upper surface of the substrate 5J.

[0180] The detailed configuration of a gas detection device 1J according to a modification of the third embodiment will be described below.

[0181] As shown in Fig. 20, gas is introduced into the flow path 6J from an opening 171J provided in the upper part. As shown in Figs. 20 and 21, an internal space Sp5 is defined within the flow path 6J. In this case, the internal space Sp5 is a space that includes the substrate 5J. The internal space Sp5 is a space defined between the first flow path cross section CS1, the second flow path cross section CS2, and the third flow path cross section CS3.

[0182] More specifically, the first flow path cross section CS1 is defined in the flow path 6J on the upstream side of the substrate 5J (above in the figure). The second flow path cross section CS2 is defined in the flow path 6J on the downstream side of the substrate 5J (forward in the figure). The third flow path cross section CS3 is defined in the flow path 6J on the downstream side of the substrate 5J (rear in the figure). More specifically, the first flow path cross section CS1 is rectangular. The second flow path cross section CS2 is rectangular. The third flow path cross section CS3 is rectangular.

[0183] The substrate 5J has one air vent 9J provided in the center of the substrate 5J. The sensitive unit 4 has a plurality of sensitive elements Ax. As shown in FIG. 21, the plurality of sensitive elements Ax are arranged side by side on the first surface 51, which is the underside of the substrate 5, so as to surround the central air vent 9J. Although two sensitive elements Ax are shown in FIG. 21, the number of sensitive elements Ax is not limited to two and can be changed as appropriate to three or more as long as they are arranged so as to surround the air vent 9J.

[0184] The internal space Sp5 is a rectangular parallelepiped space extending in the front-rear direction. As shown in Fig. 20, the sample gas that has passed through the upper opening 171J of the flow path 6J enters the internal space Sp5 from the first flow path cross section CS1. The sample gas that has passed through the first flow path cross section CS1 flows downward, collides with the second surface 52, which is the upper surface of the substrate 5J disposed at the bottom of the flow path 6J, and passes downward through the ventilation hole 9J of the substrate 5J.

[0185] The sample gas then passes through the vent hole 9J and branches into a forward flow and a backward flow on the first surface 51, which is the underside of the substrate 5J. The forward branched sample gas then flows along the first surface 51 of the substrate 5J, passes through the sensor element Ax, and reaches the second flow path cross section CS2. Meanwhile, the backward branched sample gas flows along the first surface 51 of the substrate 5J, passes through the sensor element Ax, and reaches the third flow path cross section CS3. In this way, the multiple sensor elements Ax arranged on the first surface 51 of the substrate 5J are exposed to the sample gas.

[0186] A plurality of streamlines SL are defined in the internal space Sp5. Each of the plurality of lines representing the flow of gas in the internal space Sp5 is referred to as a streamline SL. In this modification, the plurality of streamlines SL pass through the ventilation holes 9j of the substrate 5J. A plurality of sensory elements Ax are arranged on the substrate 5J so that each of the plurality of streamlines SL that pass through the sensory element Ax passes through only one sensory element Ax.

[0187] 21, only a representative flow line SL passing near the center of one sensor element Ax is shown, and two flow lines SL are shown corresponding to each of the two sensor elements Ax.

[0188] The first forward streamline SL is a line that passes through the first point P11, the vent hole 9j, the forward sensor element Ax on the first surface 51, and the second point P2. The first point P11 is the point where the gas flow that passes through the vent hole 9j and heads toward the forward sensor element Ax on the first surface 51 intersects with the first flow path cross section CS1. The second point P2 is the point where the gas flow that has passed through the forward sensor element Ax on the first surface 51 intersects with the second flow path cross section CS2.

[0189] The second rear streamline SL is a line that passes through the first point P12, the vent hole 9j, the rear sensor element Ax on the first surface 51, and the third point P3. The first point P12 is the point where the gas flow that passes through the vent hole 9j and heads toward the rear sensor element Ax on the first surface 51 intersects with the first flow path cross section CS1. The third point P3 is the point where the gas flow that has passed through the rear sensor element Ax on the first surface 51 intersects with the third flow path cross section CS3.

[0190] In other words, each of the multiple streamlines SL is a line connecting the first point P1, the sensor element Ax, and the second point P2, or a line connecting the first point P1, the sensor element Ax, and the third point P3. The first point P1 is a specific point in the flow path 6J where the gas flow that enters the internal space Sp5 and heads toward the sensor element Ax intersects with the first flow path cross section CS1. The second point P2 is a specific point in the internal space Sp5 where the gas flow that has passed through the front sensor element Ax intersects with the second flow path cross section CS2. The third point P3 is a specific point in the internal space Sp5 where the gas flow that has passed through the rear sensor element Ax intersects with the third flow path cross section CS3.

[0191] In the gas detection device 1J according to the modification of the third embodiment, as described above, the substrate 5J is arranged so that gas flowing from upstream of the flow path 6J in the direction normal to the first surface 51 of the substrate 5J impinges on the plurality of sensitive elements Ax after passing through the vent hole 9J of the substrate 5J. A plurality of gas flow lines SL are defined in the internal space Sp5 including the substrate 5J. A plurality of sensitive elements Ax are arranged on the substrate 5J so that each of the plurality of flow lines SL that pass through the sensitive element Ax passes through only one sensitive element Ax. This makes it easier to uniformize the amount of sample gas supplied to the plurality of sensitive elements Ax. In other words, the gas detection device 1J according to the modification of the third embodiment can suppress a decrease in the detection accuracy of the sample gas.

[0192] (summary) The above-described embodiments and the like disclose the following aspects.

[0193] A gas detection device (1, 1A to 1G) of a first aspect includes a sensitive part (4), a substrate (5, 5A to 5G), and a flow path (6, 6A to 6G). The sensitive part (4) changes an electrical characteristic value in response to one or more types of molecules. The substrate (5, 5A to 5G) has the sensitive part (4) arranged thereon. The flow path (6, 6A to 6G) is for supplying gas to the substrate (5, 5A to 5G). The sensitive part (4) has a plurality of sensitive elements (Ax). The substrate (5, 5A to 5G) has a mounting surface (51) on which the plurality of sensitive elements Ax are arranged. The substrate (5, 5A to 5G) is arranged so that gas flows along the mounting surface (51). In the flow path (6, 6A to 6G), an internal space (Sp1) including the substrate (5, 5A to 5G) and multiple streamlines (SL) in the internal space (Sp1) are defined. Each of the multiple lines representing the flow of gas in the internal space (Sp1) is referred to as a streamline (SL). Multiple sensor elements (Ax) are arranged on the substrate (5, 5A to 5G) so that each of the multiple streamlines (SL) that pass through a sensor element (Ax) passes through only one sensor element (Ax).

[0194] According to this embodiment, the substrate (5) is disposed in the flow path (6) so that the sample gas flows along the mounting surface (first surface 51) of the multiple sensor elements (Ax). In such a flow path (6), it becomes easier to uniformize the amount of gas supplied to the multiple sensor elements (Ax). That is, it is possible to suppress a decrease in the detection accuracy of the sample gas in the gas detection device (1, 1A to 1G) having the multiple sensor elements (Ax).

[0195] In the gas detection device (1, 1A to 1G) of the second aspect, in the first aspect, the internal space (Sp1) is a space between a first flow path cross section (CS1) and a second flow path cross section (CS2) in the flow path (6, 6A to 6G). The first flow path cross section (CS1) is defined on the upstream side of the substrate (5, 5A to 5G). The second flow path cross section (CS2) is defined on the downstream side of the substrate (5, 5A to 5G). Furthermore, each of the plurality of flow lines (SL) is a line connecting a first point (P1) and a second point (P2). The first point (P1) is a specific point where the flow of gas entering the internal space (Sp1) intersects with the first flow path cross section (CS1). The second point (P2) is a specific point in the internal space (Sp1) where the gas flow that has passed through one sensing element (Ax) intersects with the second flow path cross section (CS2).

[0196] According to this embodiment, it becomes easier to identify the flow line (SL) in the flow path (6, 6A to 6G).

[0197] In the gas detection device (1E, 1F) of the third aspect, in the first or second aspect, the plurality of sensitive elements (Ax) are three-dimensionally arranged in the flow channel (6E, 6F).

[0198] According to this embodiment, the degree of freedom in designing the arrangement of the plurality of sensitive elements (Ax) and the structure of the flow paths (6E, 6F) is increased, and therefore the gas detection device (1E, 1F) can be made smaller.

[0199] A gas detection device (1F) of a fourth aspect is any one of the first to third aspects, wherein the substrate (5F) includes a plurality of sub-substrates (7). At least one sensitive element (Ax) is arranged on each of the plurality of sub-substrates (7).

[0200] According to this embodiment, the substrate (5F) can be divided into a plurality of sub-substrates (7), thereby preventing a decrease in productivity due to an increase in the aspect ratio of the substrate (5F). In addition, by arranging at least one sensor element (Ax) on each of the plurality of sub-substrates (7), the degree of freedom in designing the arrangement of the plurality of sensor elements (Ax) and the structure of the flow path (6F) is increased.

[0201] A gas detection device (1G) of a fifth aspect is any one of the first to fourth aspects, wherein the flow path (6G) includes a plurality of branch flow paths (8). The plurality of branch flow paths (8) branch the flow of gas in the flow path (6G). A plurality of sensitive elements (Ax) are arranged on the substrate (5G) such that one sensitive element (Ax) corresponds to each of the plurality of branch flow paths (8).

[0202] According to this embodiment, the plurality of sensor elements (Ax) are arranged on the substrate (5G) so that each of the plurality of branch flow paths (8) has one sensor element (Ax), which makes it easier to uniformly supply the sample gas to each of the plurality of sensor elements (Ax). Also, since it is not necessary to consider the diffusion of the sample gas in the flow path (6G), the degree of freedom in design is increased.

[0203] The configurations according to the second to fifth aspects are not essential for the gas detection device (1, 1A to 1G) and can be omitted as appropriate.

[0204] A gas detection device (1H to 1J) of a sixth aspect includes a sensitive part (4), a substrate (5H to 5J), and a flow path (6H to 6J). The sensitive part (4) changes an electrical characteristic value in response to one or more types of molecules. The sensitive part (4) is arranged on the substrate (5H to 5J). The flow path (6H to 6J) is for supplying gas to the substrate (5H to 5J). The sensitive part (4) has a plurality of sensitive elements (Ax). The substrate (5H to 5J) has a mounting surface (51) on which the plurality of sensitive elements (Ax) are arranged. The substrate (5H to 5J) is arranged in the flow path (6H to 6J) so that gas flowing from the upstream of the flow path (6H to 6J) along the normal direction of the mounting surface (51) hits the plurality of sensitive elements (Ax). In the flow paths (6H-6J), internal spaces (Sp3-Sp5) including the substrates (5H-5J) and multiple streamlines (SL) are defined in the internal spaces (Sp3-Sp5). Each of the multiple lines representing the gas flow in the internal spaces (Sp3-Sp5) is called a streamline (SL). In this case, multiple sensor elements (Ax) are arranged on the substrates (5H-5J) so that each of the multiple streamlines (SL) that pass through a sensor element (Ax) passes through only one sensor element (Ax).

[0205] According to this embodiment, the substrates (5H-5J) are arranged on the substrates (5H-5J) so that gas flowing from upstream of the flow paths (6H-6J) in the normal direction to the mounting surface (51) of the substrates (5H-5J) impinges on the plurality of sensory elements (Ax). In such flow paths (6H-6J), it is easy to make the amount of sample gas supplied to the plurality of sensory elements Ax uniform. In other words, it is possible to suppress a decrease in the detection accuracy of the sample gas in the gas detection device (1H-1J) having the plurality of sensory elements (Ax).

[0206] A gas detection device (1i, 1J) of a seventh aspect is the same as that of the sixth aspect, except that the substrate (5i, 5J) has a vent hole (9, 9J). The vent hole (9, 9J) penetrates the substrate (5i, 5J) in the thickness direction. A plurality of flow lines (SL) pass through the vent hole (9, 9J).

[0207] According to this embodiment, the substrate (5i, 5J) has the vent holes (9, 9J), which allows the cross section of the flow path (6i, 6J) to be effectively utilized, thereby enabling the gas detector (1i, 1J) to be made smaller.

[0208] The configuration according to the seventh aspect is not an essential configuration for the gas detection device (1H to 1J), and can be omitted as appropriate. [Explanation of symbols]

[0209] 1,1A~1J Gas detection device 2. Device body 3 Evaluation equipment 4 Sensing part 5,5A~5J board 6,6A~6J flow path 7 Sub-board 8 Branching Channel 9,9J Ventilation hole 51 First surface (mounting surface) 52 Side 2 100 Air Quality Rating System Ax sensing element Sp1~Sp5 Internal space SL streamline CS1 First flow section CS2 Second flow section CS3 Third flow section P1 First point on the cross section of the flow path P2: Point on the second cross section of the flow path P3 Third point on the cross section

Claims

1. a sensitive part whose electrical characteristic value changes in response to one or more types of molecules; a substrate on which the sensitive part is disposed; a flow path for supplying a gas to the substrate; Equipped with the sensitive part has a plurality of sensitive elements, the substrate has a mounting surface on which the plurality of sensitive elements are arranged, the substrate is disposed in the flow path so that the gas flows along the placement surface; When an internal space including the substrate in the flow path and a plurality of streamlines are defined as lines each representing the flow of the gas in the internal space, the plurality of sensitive elements are arranged on the substrate such that each of the plurality of flow lines passing through the sensitive element passes through only one of the sensitive elements; Gas detection equipment.

2. the internal space is a space between a first flow path cross section defined in the flow path on the upstream side of the substrate and a second flow path cross section defined in the flow path on the downstream side of the substrate, each of the plurality of flow lines is a line connecting a first point, the one of the sensor elements, and a second point; the first point is a specific point where the flow of the gas flowing toward the one of the sensitive elements intersects with the first flow path cross section; the second point is a specific point in the internal space where the gas flow that has passed through the one sensitive element intersects with a second flow path cross section; 2. The gas detection device according to claim 1.

3. The plurality of sensitive elements are three-dimensionally arranged in the flow channel.

2. The gas detection device according to claim 1.

4. The substrate includes a plurality of sub-substrates, At least one of the sensitive elements is disposed on each of the plurality of sub-substrates.

2. The gas detection device according to claim 1.

5. The flow path is provided with a plurality of branch flow paths that branch the flow of gas within the flow path, the plurality of sensitive elements are arranged on the substrate so that one sensitive element is provided for each of the plurality of branched flow paths; 2. The gas detection device according to claim 1.

6. a sensitive part whose electrical characteristic value changes in response to one or more types of molecules; a substrate on which the sensitive part is disposed; a flow path for supplying a gas to the substrate; Equipped with the sensitive part has a plurality of sensitive elements, the substrate has a mounting surface on which the plurality of sensitive elements are arranged, the substrate is disposed in the flow path so that the gas flowing from the upstream of the flow path along the normal direction of the placement surface impinges on the plurality of sensitive elements; When an internal space including the substrate in the flow path and a plurality of streamlines are defined as lines each representing the flow of the gas in the internal space, the plurality of sensitive elements are arranged on the substrate such that each of the plurality of flow lines passing through the sensitive element passes through only one of the sensitive elements; Gas detection equipment.

7. the substrate has a vent hole penetrating through the substrate in a thickness direction, the plurality of flow lines pass through the vent; 7. The gas detection device according to claim 6.

Images