Gas detection method and information processing device

Abstract

A gas detection method according to an embodiment of the present technology includes heating a semiconductor sensor including an adsorption layer including a metal oxide, measuring a resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is present, and determining that the reducing gas contains a detection target substance when the measured resistance value is greater than another resistance value of the semiconductor sensor in an air atmosphere in which the reducing gas is not present in a first temperature range, and when the measured resistance value is less than the other resistance value in a second temperature range higher than the first temperature range.

Description

Technical Field

[0001] The present technology relates to a gas detection method and an information processing device. Background Art

[0002] Technologies for detecting and identifying gases using metal oxide (MOx) semiconductor sensors are known. For example, Patent Document 1 discloses a gas sensor comprising an adsorption layer and a sensor layer. The adsorption layer adsorbs gases including a target gas and non-target gases, and the sensor layer is covered by the adsorption layer. The sensor layer has electrical properties that vary depending on the concentration of the target gas passing through the adsorption layer. Furthermore, Patent Document 2 discloses a gas detection device that identifies the type of gas based on the output values ​​of a first gas sensor and a second gas sensor.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-223557

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-175969 Summary of the Invention

[0007] Technical problem to be solved by the invention

[0008] When a reducing gas is blown onto a heated MOx semiconductor sensor, the sensor's resistance typically begins to change at a certain temperature. Therefore, the amount of gas detected or determined can be determined based on the change in resistance (sensitivity). Furthermore, when the curves for the temperature-dependent resistance change (sensitivity) show significant differences, the type of gas can be identified. However, if the curves do not differ sufficiently, identifying the gas type becomes difficult.

[0009] In view of the above-described situation, an object of the present technology is to provide a gas detection method and an information processing device that make it possible to easily identify a specific kind of gas.

[0010] Means of solving the problem

[0011] A gas detection method according to an embodiment of the present technology includes heating a semiconductor sensor including an adsorption layer including a metal oxide.

[0012] The resistance value of the semiconductor sensor is measured in an air atmosphere in which a reducing gas is present.

[0013] When the resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present is taken as a reference, and the resistance value measured in a first temperature range is greater than the reference, and the resistance value measured in a second temperature range higher than the first temperature range is less than the reference, it is determined that the reducing gas includes a detection target substance.

[0014] The air atmosphere in which the reducing gas is not present can be dry air.

[0015] The semiconductor sensor can include a plurality of semiconductor sensors. In this case, the step of heating the semiconductor sensor includes heating the semiconductor sensors of the plurality of semiconductor sensors to respective heating temperatures different from each other, and the step of measuring the resistance value of the semiconductor sensor includes measuring respective resistance values of the semiconductor sensors of the plurality of semiconductor sensors.

[0016] The detection target substance can be a compound including a derivative of benzoic acid.

[0017] The derivative of benzoic acid can be hexyl benzoate or benzyl benzoate.

[0018] The metal oxide can be a sintered body including a metal oxide material and a catalyst metal material.

[0019] The metal oxide material can include one of tungsten oxide, indium oxide, and tin oxide, and the catalyst metal material can include iridium and iridium oxide, or palladium and palladium oxide.

[0020] A gas detection method according to another embodiment of the present technology includes heating a semiconductor sensor including an adsorption layer including a metal oxide.

[0021] The resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present is taken as a reference, and the resistance value measured in a first temperature range is greater than the reference, and the resistance value measured in a second temperature range higher than the first temperature range is less than the reference, it is determined that the reducing gas includes a detection target substance.

[0022] The ratio of the resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present to the measured resistance value is taken as a sensitivity, and when the sensitivity assumes a value less than 1 in a first temperature range, and when the sensitivity assumes a value greater than 1 in a second temperature range higher than the first temperature range, it is determined that the reducing gas includes a detection target substance.

[0023] An information processing apparatus according to an embodiment of the present technology includes an acquisition section and a determination section.

[0024] The acquisition section acquires a resistance value of a metal oxide semiconductor sensor in an air atmosphere in which a reducing gas is present.

[0025] The judgment unit uses the resistance value of the semiconductor sensor in an air atmosphere without reducing gas as a reference, and judges whether the resistance value obtained in the first temperature range is greater than the reference, and whether the resistance value obtained in the second temperature range higher than the first temperature range is less than the accuracy.

[0026] An information processing device according to another embodiment of the present technology includes an acquisition section and a determination section.

[0027] The acquisition unit acquires a resistance value of the metal oxide semiconductor sensor in an air atmosphere containing a reducing gas.

[0028] The judgment unit uses the ratio of the resistance value of the semiconductor sensor in an air atmosphere without reducing gas to the acquired resistance value as sensitivity, and judges whether the sensitivity is less than 1 in the first temperature range and whether the sensitivity is greater than 1 in the second temperature range higher than the first temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] [ Figure 1 ] Figure 1 This is a cross-sectional view schematically showing the structure of a main part of a semiconductor sensor used in an embodiment of the present technology.

[0030] [ Figure 2 ] Figure 2 Shows a driving circuit for a semiconductor sensor.

[0031] [ Figure 3 ] Figure 3 An example of how the resistance value output from a semiconductor sensor changes over time is shown.

[0032] [ Figure 4 ] Figure 4 The relationship between the heating temperature and the resistance value of the semiconductor sensor is schematically shown.

[0033] [ Figure 5 ] Figure 5 The relationship between the heating temperature and the sensitivity of the semiconductor sensor is schematically shown.

[0034] [ Figure 6 ] Figure 6 The relationship between the heating temperature and the resistance value of the semiconductor sensor in the presence of a specific type of gas is schematically shown.

[0035] [ Figure 7 ] Figure 7 The relationship between the heating temperature and the sensitivity of the semiconductor sensor in the presence of a specific type of gas is schematically shown.

[0036] [ Figure 8 ] Figure 8This is a schematic diagram for explaining a method of identifying the type of gas using differences in sensitivity.

[0037] [ Figure 9 ] Figure 9 The configuration of the gas detection system is schematically shown.

[0038] [ Figure 10 ] Figure 10 Experimental results showing the resistance value and sensitivity of the semiconductor sensor when each of (A) toluene, (B) benzene, and (C) cyclohexane is used as the reducing gas are shown.

[0039] [ Figure 11 ] Figure 11 Experimental results showing the resistance value and sensitivity of a semiconductor sensor when each of (A) hexenyl benzoate and (B) benzyl benzoate was used as a reducing gas are shown.

[0040] [ Figure 12 ] Figure 12 The structure of the gas detection device is schematically shown.

[0041] [ Figure 13 ] Figure 13 is a flowchart illustrating an example of a processing procedure performed by the gas detection device.

[0042] [ Figure 14 ] Figure 14 is a flowchart illustrating another example of a processing procedure performed by the gas detection device. DETAILED DESCRIPTION

[0043] Now, embodiments according to the present technology will be described below with reference to the accompanying drawings.

[0044] [Semiconductor Sensors]

[0045] Figure 1 1 is a cross-sectional view schematically showing the configuration of a main portion of a semiconductor sensor 10 used in an embodiment of the present technology.

[0046] The semiconductor sensor 10 includes a substrate 11 , a pair of electrodes 12 a and 12 b formed on the front surface of the substrate 11 , an adsorption layer 13 provided between the pair of electrodes 12 a and 12 b , and a heating layer 14 arranged on the rear surface of the substrate 11 .

[0047] The substrate 11 is, for example, a quartz substrate.

[0048] The pair of electrodes 12 a and 12 b each include a metal layer, such as a Ti or Au layer, or a stack of Ti or Au films, and the metal layers are formed on the front surface of the substrate 11 to be positioned opposite to each other across the gap G.

[0049] The adsorption layer 13 includes a metal oxide (MOx), which is a sintered body including a metal oxide material and a catalytic metal material. Examples of the metal oxide material include tungsten oxide, indium oxide, and tin oxide. Examples of the catalytic metal material include iridium, iridium oxide, palladium, and palladium oxide.

[0050] The heating layer 14 is used to heat the adsorption layer 13 to a specified temperature and includes, for example, a ceramic heater. The heating layer 14 is connected to a heater power supply (not shown) and can be heated to a temperature of, for example, 400° C. or less using a control device described below.

[0051] Typically, when a reducing gas is blown onto a heated MOx semiconductor sensor, the sensor's resistance value begins to change at a certain temperature. Therefore, the amount of change in resistance (sensitivity) can be used to detect the gas or determine its quantity. Furthermore, when the curve of the resistance change (sensitivity) varies significantly depending on temperature, this allows identification of the gas type.

[0052] Figure 2 The driving circuit of semiconductor sensor 10 is shown. In the figure, Rs is the sensor resistance, RL is the load resistance connected in series with sensor resistance Rs, and RH is the heater resistance that heats semiconductor sensor 10. The heating temperature of heating layer 14 is adjusted by heater voltage VH. Furthermore, when power supply voltage Vc is applied across the series resistors (Rs, RL), sensor resistance Rs is measured using the following equation based on voltage Vout across load resistance RL.

[0053] Rs=((Vc-Vout) / Vout)×RL

[0054] Figure 3 An example of temporal variation of the resistance value Rs output from the semiconductor sensor 10 is shown. In this example, the semiconductor sensor 10 is driven in an air atmosphere without a reducing gas, and a reducing gas is injected into the air atmosphere for any period of time (five seconds in this example).

[0055] Note that the air atmosphere in which no reducing gas exists refers to a clean air atmosphere, and generally refers to a dry air atmosphere in which temperature and humidity are controlled.

[0056] like Figure 3 As shown, the resistance value Rgas of the semiconductor sensor 10 in the air atmosphere containing reducing gas is smaller than the resistance value Rair of the semiconductor sensor 10 in the clean air atmosphere. When the injection of reducing gas is stopped, the output of the semiconductor sensor 10 returns to the resistance value (Rair) in the clean air atmosphere.

[0057] The sensor sensitivity is higher if the amount by which Rgas decreases from Rair is large. The ratio of Rair to Rgas (Rair / Rgas) is defined below as the sensor sensitivity.

[0058] The resistance value and the sensitivity of the semiconductor sensor 10 vary depending on the heating temperature of the heating layer 14. Figure 4 The relationship between the heating temperature and the resistance value (hereinafter also referred to as the resistance value curve) is schematically shown. Figure 5 The relationship between the heating temperature and the sensitivity (hereinafter also referred to as the sensitivity curve) is schematically shown.

[0059] In the case of a general reducing gas such as hydrogen, acetone, ethanol, toluene, benzene, or cyclohexane, as the heating temperature increases, the semiconductor sensor 10 tends to exhibit a larger amount of resistance value decrease, and exhibits a sensitivity having a value that increases to be greater than 1, as shown in Figure 4 and Figure 5 In addition, as Figure 5 schematically shown, it is possible to identify three different kinds of gases G1, G2, and G3 based on the difference in the sensitivity curve.

[0060] It is generally considered that the change in the resistance value of the semiconductor sensor 10 due to such a reducing gas is caused by oxygen desorption resulting from the redox of the metal oxide included in the adsorption layer 13.

[0061] For example, in an air atmosphere in which there is no reducing gas, oxygen is adsorbed on the surface of the metal oxide particles, and a space charge layer is formed near the surface of the particles. This results in the formation of a potential barrier at the grain boundaries and thus prevents the movement of electrons between the particles. Therefore, the resistance value increases.

[0062] When a reducing gas is blown onto the semiconductor sensor 10 in this state, the oxygen adsorbed on the surface of the metal oxide particles is consumed, thus thinning the space charge layer. This results in a decrease in the potential barrier and thus a decrease in the resistance value.

[0063] Since the resistance value curve and the sensitivity curve described above are unique to each gas, in principle, it is possible to identify the kind of gas based on the difference in these curves. However, when the difference in these curves is not large enough, it will be difficult to accurately identify the kind of gas.

[0064] On the other hand, the inventors found that a specific kind of reducing gas has a specific resistance value curve and a specific sensitivity curve, as schematically illustrated in Figure 6 and Figure 7 respectively.

[0065] In other words, the resistance value decreases in a certain temperature range (in the case of the reducing gas G1, in the range of 200 to 300°C, for example) and then increases again, as schematically shown in Figure 6In the example of 220℃ to 250℃, the temperature increases, while in the temperature range higher than the above temperature range (at Figure 6 When converted into sensor sensitivity, such as Figure 7 As shown, the sensitivity exhibits a value less than 1 in the above temperature range, and exhibits a value greater than 1 in a temperature region higher than the above temperature range (higher than or equal to about 290° C.).

[0066] It should be noted that the specific reasons for this particular curve are not yet known. However, the following are conceivable. In the low-temperature range, a specific type of gas is adsorbed, attracting electrons from the semiconductor sensor, causing the resistance to increase. In the high-temperature range, this specific type of gas is decomposed, causing the semiconductor sensor's resistance to decrease.

[0067] The specific type of gas G4 corresponding to the gas type showing the above-mentioned specific curve can be easily identified using the property that the sensitivity first decreases and then increases, such as Figure 8 shown.

[0068] Examples of the kind of gas exhibiting such a specific sensitivity curve include compounds containing derivatives of benzoic acid, such as hexenyl benzoate or benzyl benzoate (see Chemical Formula (1) shown below).

[0069] [Chemical Formula 1]

[0070]

[0071] wherein R is an alkyl group.

[0072] [Experimental example]

[0073] Inventor uses Figure 9 The illustrated gas detection system measures changes in the resistance value output from the semiconductor sensor 10 for a variety of reducing gases. Figure 9 The configuration of the gas detection system 20 is schematically shown.

[0074] The semiconductor sensor 10 is arranged in the measurement chamber 21. A dry air introduction line L1 and a reducing gas introduction line L2 are connected to the measurement chamber 21. In order to maintain a constant pressure in the measurement chamber 21, the gas introduced into the measurement chamber 21 is exhausted from the measurement chamber 21.

[0075] The dry air introduction line L1 is configured so that dry air (temperature of 25° C. and relative humidity of 31%, and this temperature and humidity also apply to the following description) can be introduced into the measurement chamber 21 via the electromagnetic valve 23 a by the driven pump 22 a .

[0076] The reducing gas introduction pipeline L2 is configured so that dry air can be introduced into the gas chamber 24 filled with reducing gas (saturated vapor) by the driven pump 22b, and so that dry air including a specific concentration of reducing gas can be introduced into the measurement chamber 21 through the solenoid valve 23b.

[0077] Each of the electrodes 12a and 12b of the semiconductor sensor 10 is a Ti / Au film having a rectangular shape of 5 mm × 4.5 mm and a thickness of 200 nm. The electrodes 12a and 12b are arranged on a substrate 11 made of quartz and having a thickness of 525 μm so that the long side of the electrode 12a and the long side of the electrode 12b are positioned opposite each other across a gap G of 5 μm. A driving voltage Vc (see Figure 2 ) is 5 V. The adsorption layer 13 is an n-type metal oxide semiconductor (WO3-Pd) including tungsten oxide corresponding to the metal oxide material and palladium corresponding to the catalyst metal material. The adsorption layer 13 has a thickness of from several micrometers to 30 micrometers.

[0078] A commercially available pump that provides a flow rate of 400 ml / min is used as the pumps 22a and 22b. Each of the solenoid valves 23a and 23b is an on-off valve that can be switched between two positions: a fully open position and a fully closed position.

[0079] The control device 25 controls the electromagnetic valves 23a and 23b and the heater power supply 26 for heating the heating layer 14 (see FIG. Figure 1 ) for heating.

[0080] The control device 25 opens one of the electromagnetic valves 23 a and 23 b and closes the other of the electromagnetic valves 23 a and 23 b so as to select one of the dry air introduction line L1 and the reducing gas introduction line L2 .

[0081] The control device 25 controls the heating temperature of the semiconductor sensor 10 by controlling the heater power supply 26. The heating temperature of the semiconductor sensor 10 is arbitrarily adjusted within the range of 40°C to 380°C.

[0082] Based on the output Vout of the semiconductor sensor 10 (see Figure 2), the measuring device 27 acquires the resistance value Rs of the semiconductor sensor 10 at a plurality of temperatures within the above-mentioned heating temperature range. When dry air is introduced into the measurement chamber 21 via the dry air introduction line L1, the resistance value Rs corresponds to the resistance value (Rair) in an air atmosphere without the presence of reducing gas. When a mixed gas obtained by mixing reducing gas and dry air is introduced into the measurement chamber 21 via the reducing gas introduction line L2, the resistance value Rs corresponds to the resistance value (Rgas) in an air atmosphere with the presence of reducing gas.

[0083] Using the gas detection system 20 having the above-described configuration, the response characteristics of the semiconductor sensor 10 were evaluated with respect to various reducing gases.

[0084] Figure 10 Shown are a resistance value curve (in the upper part) and a sensitivity curve (in the lower part) of the semiconductor sensor 10 when each of (A) toluene, (B) benzene, and (C) cyclohexane is used as the reducing gas.

[0085] As shown in the figure, these types of gases all show a change in resistance value at a heating temperature greater than or equal to 100°C, and as the heating temperature increases, the amount of resistance reduction tends to gradually increase. Similarly, as the heating temperature increases, the sensor sensitivity tends to gradually increase. The sensitivity curves of these types of gases show the same Figure 5 The typical reducing gas sensitivity curves shown are consistent with those shown.

[0086] on the other hand, Figure 11 Shown are a resistance value curve (in the upper part) and a sensitivity curve (in the lower part) of the semiconductor sensor 10 when each of (A) hexenyl benzoate and (B) benzyl benzoate is used as the reducing gas.

[0087] For both hexyl benzoate and benzyl benzoate, in the first temperature range, when the specific type of gas is blown onto the semiconductor sensor 10, the measurement value (Rgas) of the semiconductor sensor 10 obtained tends to be larger than the measurement value (Rair) obtained before the specific type of gas is blown. On the other hand, in the second temperature range higher than the first temperature range, the magnitude relationship between Rgas and Rair is reversed (temperature range higher than the temperature indicated by the arrow in the figure), and Rgas is smaller than Rair.

[0088] Likewise, the sensor sensitivity exhibits a value less than 1 in the first temperature range, and the sensor sensitivity exhibits a value greater than 1 in the second temperature range (a temperature range higher than the temperature indicated by the arrow in the figure), as shown in FIG. Figure 11 As shown in (A) and (B).

[0089] It should be noted that the first temperature range described above refers to a range from about 120° C. to about 320° C. in the case of hexenyl benzoate, and refers to a range from about 120° C. to about 260° C. in the case of benzyl benzoate.

[0090] In addition to the gases described above, Figure 11 Examples of gas species of the specific resistance value curves and sensitivity curves shown in (A) and (B) also include benzoic acid derivatives such as ethyl benzoate, propyl benzoate, and vinyl benzoate.

[0091] [Gas detection method]

[0092] For example, a detection device including a dangerous object detection function described below can be used as an application example of the semiconductor sensor 10 .

[0093] To detect hazardous materials such as flammable liquids (such as gasoline), high-pressure gases (such as gas lighters), or explosives, for example, in an airport terminal, the presence of the hazardous material may be inferred by detecting volatile gases generated from the hazardous material.

[0094] Volatile gases generated from hazardous materials include a variety of volatile gases, such as hydrogen (H2), carbon monoxide (CO), toluene, acetone, formaldehyde, methanol, ethanol, nitrogen dioxide (NO2), sulfur dioxide (SO2), and hydrogen chloride (HCl). On the other hand, such volatile gases can also be generated from non-hazardous objects or exist in the environment. This can make hazardous material detection difficult or may lead to erroneous detection. Therefore, a marker substance for detection can be added to the hazardous material or mixed with the hazardous material in advance to facilitate its detection.

[0095] Chemical reaction detection, which uses reagents that react with volatile gases generated by hazardous substances or markers for detection, is a common method for detecting hazardous substances. This method offers the advantages of using small, lightweight devices and being low-cost. However, it also presents the following challenges.

[0096] - The reagents are not reusable, and thus this approach is not suitable for large-scale screening.

[0097] - A reagent needs to be provided for each hazardous substance, and it takes time to introduce the noble gas into the reagent.

[0098] -Since the sensitivity is not very high, it is difficult to detect hazardous substances with low vapor pressure.

[0099] Therefore, the dangerous substance is immersed in a solvent (a marker substance for detection) in advance, or the solvent is attached to the dangerous substance in advance or the dangerous substance carries the solvent, and the gas volatilized from the solvent is detected by a metal oxide (MOx) semiconductor sensor, which makes it possible to detect the dangerous substance or determine the amount of the dangerous substance.

[0100] When a reducing gas exhibiting a specific sensitivity curve (such as the benzoic acid derivative described above) is used as a labeling substance for detection, this makes it possible to easily identify the type of gas compared to the case where the general reducing gas (volatile gas) described above is detected.

[0101] In order to identify the type of gas, a resistance value curve of the semiconductor sensor 10 may be referred to, or a sensitivity curve of the semiconductor sensor 10 may be referred to.

[0102] When referring to the resistance curve, semiconductor sensor 10 including an adsorption layer containing a metal oxide is heated, and the resistance value (Rgas) of semiconductor sensor 10 in an air atmosphere containing a reducing gas is measured. Using the resistance value (Rair) of semiconductor sensor 10 in an air atmosphere without a reducing gas as a reference, if the resistance value (Rgas) measured in a first temperature range is greater than the reference, and the resistance value (Rgas) measured in a second temperature range higher than the first temperature range is less than the reference, it is determined that the reducing gas contains the detection target substance.

[0103] On the other hand, referring to the sensitivity curve, the semiconductor sensor 10 including the adsorption layer containing the metal oxide is heated, and the resistance value (Rgas) of the semiconductor sensor 10 is measured in an air atmosphere containing a reducing gas. Regarding the sensitivity (Rair / Rgas), which is the ratio of the resistance value of the semiconductor sensor 10 in an air atmosphere without a reducing gas to the measured resistance value (Rgas), if the sensitivity exhibits a value less than 1 in a first temperature range and exhibits a value greater than 1 in a second temperature range higher than the first temperature range, it can be determined that the reducing gas includes the detection target substance.

[0104] (Information Processing Device)

[0105] In the gas detection system described above, the measuring device 27 may be configured as a device for detecting a reducing gas including a derivative of benzoic acid.

[0106] Figure 12 The configuration of the measuring device 27 is schematically shown. The measuring device 27 is a computer (information processing device) including a CPU 271 and a memory 272 .

[0107] The CPU 271 includes an acquisition unit 271a and a determination unit 271b. The acquisition unit 271a acquires the resistance value Rgas of the semiconductor sensor 10 in an air atmosphere containing a reducing gas.

[0108] The acquisition section 271 a may include a calculation section that converts the output (Vout) of the semiconductor sensor 10 into a resistance value Rgas.

[0109] The determination section 271 a is configured to determine whether the resistance value curve or the sensitivity curve of the semiconductor sensor 10 is a specific curve based on the resistance value Rgas of the semiconductor sensor 10 acquired by the acquisition section 271 a .

[0110] The memory 272 is an information storage device such as a semiconductor memory or a hard disk. The memory 272 stores therein a program for operating the acquisition unit 271a and the determination unit 271b as functional blocks of the CPU 271. Furthermore, the memory 272 stores a plurality of data items, each of which relates to a resistance value curve and a sensitivity curve of the semiconductor sensor 10 in an air atmosphere without a reducing gas.

[0111] The output of the measuring device 27 can be displayed on the display unit 28. The display unit 28 displays, for example, Figure 10 1 or 11 show the resistance value curve and sensitivity curve of the semiconductor sensor 10.

[0112] (Process 1)

[0113] Figure 13 is a flowchart illustrating an example of a processing procedure performed by the CPU 271 .

[0114] First, the acquisition unit 271 a acquires the resistance value (Rgas) of the semiconductor sensor 10 in an air atmosphere containing a reducing gas (step 101 ).

[0115] Next, the determination unit 271b determines whether the resistance value (Rgas) measured in the first temperature range is greater than the resistance value (Rair) of the semiconductor sensor in an air atmosphere without reducing gas (step 102).

[0116] When Rgas>Rair ("Yes" in step 102), the judgment unit 271b further determines whether the resistance value (Rgas) measured in the second temperature range higher than the first temperature range is less than the resistance value (Rair), which is the resistance value of the semiconductor sensor in an air atmosphere without the presence of reducing gas (step 103).

[0117] If the determination result is "yes" in steps 102 and 103, the determination unit 271b determines that the reducing gas is the detection target gas (gas containing a derivative of benzoic acid) (step 104). If the determination result is "no" in at least one of steps 102 and 103, the determination unit 271b determines that the reducing gas is a non-detection target gas (gas not containing a derivative of benzoic acid) (step 105).

[0118] (Process 2)

[0119] Figure 14 is a flowchart showing another example of the processing procedure performed by the CPU 271.

[0120] First, the acquisition unit 271 a acquires the resistance value (Rgas) of the semiconductor sensor 10 in an air atmosphere containing a reducing gas (step 201 ).

[0121] Next, the judgment unit 271b judges whether the sensitivity (Rair / Rgas) of the ratio of the resistance value (Rair) of the semiconductor sensor, which is the resistance value in an air atmosphere without reducing gas in the first temperature range, to the measured resistance value (Rgas) is less than 1 (step 202).

[0122] When Rair / Rgas<1 (“Yes” in step 202 ), the determination unit 271 b further determines whether the sensitivity exhibits a value greater than 1 in a second temperature range higher than the first temperature range (step 203 ).

[0123] If the determination result is "yes" in steps 202 and 203, the determination unit 271b determines that the reducing gas is the detection target gas (gas containing a derivative of benzoic acid) (step 204). If the determination result is "no" in at least one of steps 202 and 203, the determination unit 271b determines that the reducing gas is a non-detection target gas (gas not containing a derivative of benzoic acid) (step 205).

[0124] The first and second temperature ranges may be set in advance, or whether or not there are regions corresponding to the first and second temperature ranges may be determined after all measurement values ​​at various temperatures are acquired.

[0125] Furthermore, the resistance value of the semiconductor sensor 10 at each heating temperature may be resistance measured in a specific sampling period while increasing the heating temperature of the semiconductor sensor 10 at a specific heating rate.

[0126] Alternatively, measurement values ​​may be used when a plurality of semiconductor sensors 10 are used and when the semiconductor sensors in the plurality of semiconductor sensors are heated to different heating temperatures, respectively.

[0127] [Other applications]

[0128] The gas detection method described above can also be applied to a case where gasoline or city gas is stored in order to detect leakage of a flammable liquid or vaporization of a flammable liquid (leakage of gas).

[0129] In this case, a substance containing a benzoic acid derivative is added to gasoline or city gas as a marker for detection, and a metal oxide (MOx) semiconductor gas sensor is installed near a flammable liquid storage location to detect leakage or vaporization of the flammable liquid. Furthermore, in this application, the marker's specific resistance curve or sensitivity curve can be used to detect liquid or gas leaks with high sensitivity.

[0130] It should be noted that the present technology can also adopt the following configurations.

[0131] (1) A gas detection method comprising:

[0132] heating a semiconductor sensor, the semiconductor sensor comprising an adsorption layer, the adsorption layer comprising a metal oxide;

[0133] measuring the resistance value of the semiconductor sensor in an air atmosphere containing a reducing gas; and

[0134] Taking the resistance value of the semiconductor sensor in an air atmosphere without the reducing gas as a reference, when the resistance value measured in a first temperature range is greater than the reference, and when the resistance value measured in a second temperature range higher than the first temperature range is less than the reference, it is determined that the reducing gas contains the detection target substance.

[0135] (2) The gas detection method according to (1), wherein

[0136] The air atmosphere in which the reducing gas is not present is dry air.

[0137] (3) The gas detection method according to (1) or (2), wherein

[0138] The semiconductor sensor includes a plurality of semiconductor sensors,

[0139] The step of heating the semiconductor sensors comprises heating the plurality of semiconductor sensors to different heating temperatures, and

[0140] The step of measuring the resistance value of the semiconductor sensor includes measuring the resistance values ​​of the plurality of semiconductor sensors respectively.

[0141] (4) The gas detection method according to any one of (1) to (3), wherein

[0142] The detection target substance is a compound including a derivative of benzoic acid.

[0143] (5) The gas detection method according to (4), wherein

[0144] The derivative of benzoic acid is hexenyl benzoate or benzyl benzoate.

[0145] (6) The gas detection method according to any one of (1) to (5), wherein

[0146] The metal oxide is a sintered body including a metal oxide material and a catalyst metal material.

[0147] (7) The gas detection method according to (6), wherein

[0148] The metal oxide material includes tungsten oxide, indium oxide, or tin oxide, and

[0149] The catalyst metal material includes iridium and an oxide thereof, or palladium and an oxide thereof.

[0150] (8) A gas detection method comprising:

[0151] heating a semiconductor sensor including an adsorption layer including a metal oxide;

[0152] measuring a resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present; and

[0153] determining that the reducing gas includes a detection target substance when a sensitivity, which is a ratio of a resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present to the measured resistance value, is less than 1 in a first temperature range and is greater than 1 in a second temperature range higher than the first temperature range.

[0154] (9) An information processing apparatus comprising:

[0155] an acquisition section that acquires a resistance value of a metal oxide semiconductor sensor in an air atmosphere in which a reducing gas is present; and

[0156] a determination section that determines whether the acquired resistance value is greater than a reference value, which is a resistance value of the semiconductor sensor in an air atmosphere in which a reducing gas is not present, in a first temperature range and whether the acquired resistance value is less than the reference value in a second temperature range higher than the first temperature range.

[0157] (10) An information processing apparatus comprising:

[0158] an acquisition unit that acquires a resistance value of the metal oxide semiconductor sensor in an air atmosphere containing a reducing gas; and

[0159] A judgment unit, which uses the ratio of the resistance value of the semiconductor sensor in an air atmosphere without a reducing gas and the measured resistance value as sensitivity, and judges whether the sensitivity is less than 1 in a first temperature range and whether the sensitivity is greater than 1 in a second temperature range higher than the first temperature range.

[0160] Reference numerals

[0161] 10 Semiconductor Sensors

[0162] 11 base plate

[0163] 12a, 12b electrodes

[0164] 13 Adsorption layer

[0165] 14 Heating layer

[0166] 20 Gas Detection System

[0167] 27 Measuring device

[0168] 271a Acquisition Department

[0169] 271b Judgment Department

Claims

1. A gas detection method, comprising: heating a semiconductor sensor, the semiconductor sensor comprising an adsorption layer, the adsorption layer comprising a metal oxide; measuring the resistance value of the semiconductor sensor in an air atmosphere containing a reducing gas; and Taking the resistance value of the semiconductor sensor in an air atmosphere without the reducing gas as a reference, when the resistance value measured in a first temperature range is greater than the reference, and when the resistance value measured in a second temperature range higher than the first temperature range is less than the reference, it is determined that the reducing gas contains a detection target substance, The detection target substance is a compound including a derivative of benzoic acid.

2. The gas detection method according to claim 1, wherein The air atmosphere in which the reducing gas is not present is dry air.

3. The gas detection method according to claim 1, wherein The semiconductor sensor includes a plurality of semiconductor sensors, The step of heating the semiconductor sensors comprises heating the plurality of semiconductor sensors to different heating temperatures, and The step of measuring the resistance value of the semiconductor sensor includes measuring the resistance values ​​of the plurality of semiconductor sensors respectively.

4. The gas detection method according to claim 1, wherein The derivative of benzoic acid is hexenyl benzoate or benzyl benzoate.

5. The gas detection method according to claim 1, wherein The metal oxide is a sintered body including a metal oxide material and a catalyst metal material.

6. The gas detection method according to claim 5, wherein The metal oxide material includes tungsten oxide, indium oxide or tin oxide, and The catalyst metal material includes iridium and its oxide, or palladium and its oxide.

7. A gas detection method comprising: heating a semiconductor sensor, the semiconductor sensor comprising an adsorption layer, the adsorption layer comprising a metal oxide; measuring the resistance value of the semiconductor sensor in an air atmosphere containing a reducing gas; and a ratio of a resistance value of the semiconductor sensor in an air atmosphere without a reducing gas and a measured resistance value as sensitivity, and when the sensitivity is less than 1 in a first temperature range and greater than 1 in a second temperature range higher than the first temperature range, determining that the reducing gas includes a detection target substance; The detection target substance is a compound including a derivative of benzoic acid.

8. An information processing device comprising: an acquisition unit configured to acquire a resistance value of the metal oxide semiconductor sensor in an air atmosphere containing a reducing gas; and a determination unit that uses the resistance value of the semiconductor sensor in an air atmosphere without a reducing gas as a reference and determines whether the resistance value obtained in a first temperature range is greater than the reference and whether the resistance value obtained in a second temperature range higher than the first temperature range is less than the reference, When the resistance value obtained in the first temperature range is greater than the reference and the resistance value obtained in the second temperature range is less than the reference, the judgment unit determines that the reducing gas contains a detection target substance, and the detection target substance is a compound including a derivative of benzoic acid.

9. An information processing device comprising: an acquisition unit configured to acquire a resistance value of the metal oxide semiconductor sensor in an air atmosphere containing a reducing gas; and a determination unit that uses a ratio of a resistance value of the semiconductor sensor in an air atmosphere without a reducing gas to the measured resistance value as a sensitivity, and determines whether the sensitivity is less than 1 in a first temperature range and greater than 1 in a second temperature range higher than the first temperature range; When the sensitivity is less than 1 in the first temperature range and greater than 1 in the second temperature range, the determination unit determines that the reducing gas contains a detection target substance, and the detection target substance is a compound including a derivative of benzoic acid.

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