Method for manufacturing an odor sensor and odor sensor

Abstract

To provide a method for producing an odor sensor that can increase the degree of freedom in the combination of a main agent and an additive used in an odor adsorption part without reducing the detection accuracy of the odor sensor, and to provide the odor sensor. [Solution] The odor adsorption section 313 comprises a base agent 315 having a porous structure 316 that is continuous in the thickness direction Dr of the odor adsorption section 313, and an additive 317 that is added to the base agent 315, and generates a change in electrical characteristics when the odor substance is not adsorbed to the additive 317 and when it is adsorbed. The detection section 314 is an element that outputs the change in electrical characteristics as a signal, and comprises a film formation process in which the base agent 315 is formed into a film on the detection section 314, and an addition process in which the additive 317 is added to the base agent 315 applied to the detection section 314, and after the addition process, the additive 317 penetrates into the porous structure 316 of the base agent 315.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an odor sensor and an odor sensor. [Background technology]

[0002] Conventionally, odor sensors have been used to detect odorous substances contained in gases in order to measure odor intensity or identify the type of odor. Odor sensors, for example, have an adsorption film that adsorbs odorous substances and a detection unit that detects changes in the surface state (surface characteristics) resulting from the adsorption of odorous substances to the adsorption film (see, for example, Patent Document 1). The adsorption film of an odor sensor is made of a material with high electronic or ionic conductivity (excellent conductivity) (hereinafter referred to as a conductive material), such as a conductive polymer such as polyaniline or an ionic liquid material. The detection unit uses a field-effect transistor sensor capable of detecting changes in the electrical characteristics of the adsorption film, or a charge-transfer sensor array (hereinafter referred to as a CMOS sensor) as described in Non-Patent Document 1. The adsorption film is formed by adding an additive capable of adsorbing odors to a base material such as a conductive polymer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 085939 [Non-patent literature]

[0004] [Non-Patent Document 1] Niina, N., Iwata, T., Hashizume, K., Kuroki, S., and Sawada, K. (2017), Gas distribution imaging using a charge-transfer sensor array with a polyaniline sensitive film, 64th Spring Meeting of the Japan Society of Applied Physics, 16p-416-6 Summary of the Invention [Problem to be solved by the invention]

[0005] However, some additives used in adsorption films may be incompatible with the base material, making film formation difficult. Therefore, it is necessary to consider the combination of the base material and the additive, which may limit the freedom of material selection. Furthermore, depending on the type of additive, the adsorption film formed on the detection unit may not be uniformly formed, which may reduce the detection accuracy of the odor sensor. Furthermore, there is a method in which the additive is applied to the base material to allow the additive to penetrate into the base material. However, in this case, depending on the type of additive, the additive may not penetrate into the base material and may only remain on the surface of the base material. This also may reduce the detection accuracy of the odor sensor.

[0006] The present invention has been made in consideration of the above circumstances, and an exemplary objective thereof is to provide a method for manufacturing an odor sensor and an odor sensor that can increase the degree of freedom in the combination of the main agent and additives used in the odor adsorption section without reducing the detection accuracy of the odor sensor. [Means for solving the problem]

[0007] In order to solve the above problems, an exemplary aspect of the present invention is a method for producing an odor sensor, which has the following configuration.

[0008] A method for producing an odor sensor having an odor adsorption portion and a base portion, comprising: The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, a film-forming step of forming a film of the base material on the base; an adding step of adding the additive to the base material applied to the base; and A method for producing an odor sensor, wherein after the adding step, the additive penetrates into the nanoporous structure of the base material.

[0009] In order to solve the above problems, an odor sensor as an exemplary aspect of the present invention has the following configuration.

[0010] An odor sensor having an odor adsorption portion and a base portion, The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, An odor sensor, wherein the additive is infiltrated into the nanoporous structure of the base material.

[0011] Further objects and other features of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for manufacturing an odor sensor and an odor sensor that can increase the degree of freedom in the combination of the main agent and additives used in the odor adsorption section without reducing the detection accuracy of the odor sensor. [Brief explanation of the drawings]

[0013] [Figure 1] Schematic diagrams showing the general configuration of an odor sensor according to an embodiment, in which (a) is a top view of the odor sensor, and (b) is a cross-sectional view taken along line AA in (a). [Figure 2] 1A and 1B are schematic diagrams illustrating the general configuration of an odor sensor according to an embodiment of the present invention; FIG. 1A is a top view of the odor sensor; and FIG. 1B is a cross-sectional view taken along line BB in FIG. [Figure 3] 1 is a schematic diagram showing a general configuration of an odor data analysis device according to an embodiment; [Figure 4] Schematic diagrams showing the odor sensor of embodiment 1, in which (a) is a schematic cross-sectional view of the odor sensor, and (b) is a schematic top view of the odor sensor. [Figure 5]1A and 1B are diagrams illustrating a method for producing an odor sensor according to the first embodiment, in which (a) is a schematic diagram illustrating a detection unit, (b) is a schematic diagram illustrating a film-forming process, and (c) is a schematic diagram illustrating an addition process. [Figure 6] Schematic diagrams illustrating the porous structure fabrication method 1 of the first embodiment, including (a) a schematic diagram illustrating a mixing step, (b) a schematic diagram illustrating a first dissolving step, (c) a schematic diagram illustrating a coating step, (d) a schematic diagram illustrating a second dissolving step, and (e) a schematic diagram illustrating a drying step. [Figure 7] Schematic diagrams showing the results of producing an odor adsorption part by changing the amount of resin relative to the base agent of embodiment 1, where (a) is a schematic diagram showing an odor adsorption part when the amount of resin is small, (b) is a schematic diagram showing an odor adsorption part when the amount of resin is appropriate, and (c) is a schematic diagram showing an odor adsorption part when the amount of resin is large. [Figure 8] 1A and 1B are diagrams illustrating a porous structure fabrication method 2 according to the first embodiment, in which (a) is a schematic diagram illustrating a dissolution process, (b) is a schematic diagram illustrating a coating process, (c) is a schematic diagram illustrating a deposition process, and (d) is a schematic diagram illustrating a drying process. [Figure 9] 1A and 1B are diagrams illustrating the effects of the first embodiment, in which (a) is a schematic diagram of an odor adsorption section of Example 2, (b) is a schematic diagram of an odor adsorption section of Comparative Example 1, (c) is a schematic diagram of an odor adsorption section of Example 3, and (d) is a schematic diagram of an odor adsorption section of Comparative Example 2. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of an odor sensor unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, "odorous substance" broadly refers to a substance that can be adsorbed to an adsorption film (odor adsorption section). Therefore, "odorous substance" also includes substances that are not generally considered to be odor-causing substances, substances that are not recognized as odorous substances, or unknown odorous substances. Furthermore, "odorous substance" includes not only individual odorous substances but also "aggregates of multiple odorous substances." Furthermore, in the following embodiments, the CMOS sensor refers to the sensors described in the non-patent literature mentioned above, but is not limited to this.

[0015] <Odor sensor> 1 shows an odor sensor 100, where (a) is a top view of the odor sensor 100 and (b) is a cross-sectional view taken along line AA in (a). The odor sensor 100 has multiple sensor elements 110 and a substrate 120. The sensor elements 110 have an adsorption film 112, a detection unit 114, and electrodes 116.

[0016] The odor sensor 100 in Fig. 1 has, for example, nine sensor elements 110a to 110i. Specifically, sensor element 110a has an adsorption film 112a, a detection unit 114a, and an electrode 116a; sensor element 110b has an adsorption film 112b, a detection unit 114b, and an electrode 116b; and sensor element 110i has an adsorption film 112i, a detection unit 114i, and an electrode 116i. Note that when the sensor element (adsorption film, detection unit, electrode) is not specified, the subscripts a to i (including j to l, which will be described later) are omitted. The adsorption film 112 is a film that adsorbs odorous substances, and will be described in detail later.

[0017] The detection unit 114 detects changes in the adsorption state (also referred to as adsorption characteristics) resulting from the adsorption of an odorant to the adsorption film 112. Note that the term "adsorption of an odorant to the adsorption film 112" refers not only to the adsorption of an odorant to the surface of the adsorption film 112, but also to the absorption of an odorant into the interior of the adsorption film 112. Here, changes in the adsorption state resulting from the adsorption of an odorant to the adsorption film 112 include changes in the mechanical, optical, or electrical characteristics of the odorant. The detection unit 114 outputs the change in the adsorption state of the adsorption film 112, for example, as a signal. In other words, the detection unit 114 also functions as a signal conversion unit (transducer).

[0018] "Changes in mechanical properties" include, for example, changes in the resonant frequency of a quartz crystal microbalance (QCM), changes in the velocity of surface acoustic waves, and changes in the expansion / contraction or deflection of a film in a piezoelectric element. "Changes in optical properties" include changes in absorption wavelength, absorbance, fluorescence / luminescence properties, and refractive index in surface plasmon resonance (SPR) elements. "Changes in electrical properties" include, for example, changes in electrical conductivity, resistance, dielectric constant, electrochemical impedance, and other properties in charge-coupled devices, changes in the redox potential of oxide semiconductor sensors, and changes in gate current, gate voltage, impedance, band gap, and other properties in field-effect transistor (FET) sensors and CMOS sensors.

[0019] Examples of elements used in the detection unit 114 include the following elements (sensors): a quartz crystal oscillator sensor (QCM), a surface acoustic wave sensor, a field effect transistor (FET) sensor, a metal oxide semiconductor sensor, an organic conductive polymer sensor, an electrochemical sensor, etc. The elements used in the detection unit 114 are not particularly limited to these, and various elements can be used as appropriate depending on the purpose of use of the odor sensor 100, etc.

[0020] The "adsorption state of the odorous substance on the adsorption film 112" also includes, for example, the "amount of the odorous substance adsorbed on the adsorption film 112." An increase or decrease in the amount of the odorous substance adsorbed on the adsorption film 112 changes the mechanical, optical, or electrical properties of the adsorption film 112, and the detection unit 114 detects the amount of change to detect the adsorption state of the odorous substance on the adsorption film 112.

[0021] The electrode 116 can be formed of a predetermined conductive material. Examples of the predetermined conductive material include inorganic materials and organic materials. Examples of inorganic materials include gold, silver, platinum, chromium, titanium, aluminum, nickel, nickel-based alloys, and silicon. Examples of organic materials include nanocarbon materials such as polypyrrole, polyaniline, carbon, carbon nanotubes, and graphene.

[0022] The substrate 120 is, for example, flat and has a surface 120a and a surface 120b, with the sensor element 110 mounted on one surface 120a and the electrode 116 mounted on the other surface 120b (see FIG. 1(b)). The substrate 120 may be, for example, a silicon substrate, a substrate made of quartz crystal, a printed wiring board, a ceramic substrate, a resin substrate, or the like. The substrate 120 may also be a multilayer wiring board such as an interposer substrate.

[0023] <Sensor element> The odor sensor 100 shown in Fig. 1(a) has nine sensor elements 110a-110i arranged in a 3-row x 3-column configuration, but the number and arrangement (disposition) of the sensor elements 110 are not limited to this. Furthermore, the sensor element 110 shown in Fig. 1 has a one-to-one correspondence between the detection unit 114 and the adsorption film 112, but this is not limiting. Fig. 2 is a diagram showing another correspondence between the detection unit 114 and the adsorption film 112, where (a) is a top view of the odor sensor 100 and (b) is a cross-sectional view taken along line BB in (a).

[0024] As shown in FIG. 2, one adsorption film 112j may correspond to three detection units 114a, 114d, and 114g, thereby forming three sensor elements 110a, 110d, and 110g. Alternatively, one adsorption film 112k may correspond to two detection units 114b and 114c, thereby forming two sensor elements 110b and 110c. Furthermore, one adsorption film 112l may correspond to four detection units 114e, 114f, 114h, and 114i, thereby forming four sensor elements 110e, 110f, 110h, and 110i. That is, one adsorption film 112 may be provided on n detection units 114 to form n sensor elements 110. Here, n is an integer greater than or equal to 1. Furthermore, one or more sensor elements 110 may be used as reference sensor elements 110 without forming the adsorption film 112 on the detection portion 114 .

[0025] <Odor data analysis device> 3 is a schematic diagram showing the general configuration of the odor data analysis device 200 of Embodiment 1. The odor data analysis device 200 has the odor sensor 100 and an analysis unit 220 described above.

[0026] The analysis unit 220 is configured to analyze the odor data F1 output from the odor sensor 100. The analysis unit 220 is primarily configured with a central processing unit (CPU) 220a and may also have a storage device (memory) 220b. The memory 220b may be provided externally, separate from the analysis unit 220. The analysis unit 220 also has a data input / output port 220c. The input / output port 220c has the function of receiving odor data F1 from the odor sensor 100 and the function of transmitting calculated data R to a control unit (not shown) as a result of calculation processing by the CPU 220a. The control unit (not shown) may be the control unit of an external device, such as a personal computer, to which the odor data analysis device 200 is connected via known wired or wireless communication means.

[0027] An analysis program P for analyzing the odor data F1 is stored in the memory 220b. This analysis program P analyzes the odor data F1 by causing the analysis unit 220 as a computer, i.e., the CPU 220a as the main component of the analysis unit 220, to execute known arithmetic processing. Note that although the data analysis device 200 in FIG. 3 includes one odor sensor 100, it may also include multiple odor sensors 100.

[0028] [Embodiment 1] The odor adsorption section (adsorption film) is formed (film-formed) by adding an additive, such as a resin (different from the main agent) with odor adsorption properties to a main agent such as resin. The resin used as the main agent may or may not have odor adsorption properties. Some additives used in the odor adsorption section are incompatible with the main agent and are difficult to form a film with. Furthermore, depending on the type of additive, such as whether it is acidic or basic, some additives may or may not be able to form a film on the detection section. Furthermore, one method of forming the odor adsorption section involves applying a main agent to the detection section and then applying an additive to the main agent. However, for example, acidic and basic additives may penetrate into the main agent, but neutral additives may not penetrate into the main agent. The odor adsorption section (adsorption film) of embodiment 1 is formed by adding an additive to a main agent having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section. This improves the flexibility of the combination of the main agent and additive, regardless of their compatibility, without reducing the detection accuracy of the odor sensor.

[0029] <Configuration of odor sensor> The odor sensor of Embodiment 1 will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing an odor sensor 300 of Embodiment 1, where Fig. 4(a) is a schematic cross-sectional view of the odor sensor 300 and Fig. 4(b) is a schematic top view of the odor sensor 300.

[0030] The odor sensor 300 of embodiment 1 has an odor adsorption section 313 (corresponding to the adsorption film 112 described above) and a detection section 314 (corresponding to the detection section 114 described above) as a base. The odor adsorption section 313 has a base agent 315 as a main agent and an additive 317 (shown hatched). The base agent 315 has a porous structure (hereinafter referred to as a porous structure) 316. The pore diameter (pore size) of each pore in the porous structure 316 is nanoscale. As shown in FIG. 4(a), the porous structure 316 has pores formed continuously in the thickness direction Dr of the odor adsorption section 313. Furthermore, as shown in FIG. 4(b), nanoscale pores of various pore diameters are formed on the surface of the base agent 315. Note that in FIG. 4(b), only some of the porous structures 316 are labeled.

[0031] The pores formed on the surface of the base agent 315 are connected to each other to form a porous structure 316 that continues to the detection section 314. In other words, the base agent 315 is sponge-like. The base agent 315 is, for example, a resin or a conductive polymer, but is not limited to these. The base agent 315 may be made of polyvinyl chloride, polymethyl methacrylate, polybutyl methacrylate, polyethylene glycol, polyvinyl alcohol, polyvinylidene fluoride, cycloolefin polymer, polyaniline, polypyrrole, polythiophene, or a copolymer of these resins.

[0032] The additive 317 causes a change in potential in the detection unit 314 when an odorant is not adsorbed and when it is adsorbed. The additive 317 is not only applied to the surface of the base agent 315, but also penetrates into the porous structure 316 of the base agent 315. In the odor adsorption unit 313 of embodiment 1, the additive 317 penetrates into the porous structure 316 formed in the base agent 315, which increases the degree of freedom in combining the base agent 315 and the additive 317, regardless of their compatibility.

[0033] The additive may include any material that can be introduced into the porous structure 316. The additive may be, for example, a salt containing an ionic liquid. The salt may be, for example, a combination of an anion and a cation as described below. Anions: Examples of anions include halide ions such as chloride ions, bromide ions, and iodide ions, chlorine oxide ions, sulfate ions, nitrate ions, borate ions, tetrachloroferrate (III) ions, tetrafluoroborate ions, hexafluorophosphate ions, hexafluoroantimonate ions, alkylsulfonate ions, and alkylphosphate ions. Alkyl phosphinate ion, alkyl phosphonate ion, alkyl dithiophosphate ion, thiocyanate ion, alkyl sulfate ion, aromatic sulfonate ions such as benzenesulfonic acid, carboxylate ion, bis(perfluoroalkylsulfonyl)imide anion, dicyanamide anion, tricyanomethanide anion Cations: metal ions such as sodium and potassium, ammonium ions, alkylammonium ions, alkylphosphonium ions, alkylimidazolium ions, alkylpyridinium ions, alkylpiperidinium ions, alkylpiperazinium ions, alkylmorpholinium ions, alkylpyrrolidinium ions, and alkylsulfonium ions

[0034] The additive may be an acid, including an organic acid, such as a proton adduct of one of the above-mentioned anions. The additive may be a base including an organic base, such as a hydroxide ion adduct or a proton desorbent of the various cations mentioned above. The additive may be, for example, a self-organizing material. Examples of the self-organizing material include organic silane compounds, thiols, phosphonic acids, and the like that form self-assembled monolayers. Other examples of the self-organizing material include liquid crystal materials and organic crystals. The additive may be, for example, a polymer material, which may include common resins such as polyvinyl alcohol and fluoropolymers, as well as polymer brushes obtained by graft polymerization on the surface of a material. The additive may be, for example, nanoparticles. Inorganic nanoparticles include nanoparticles of various metals, semiconductors, and oxides, as well as polymer nanoparticles obtained by nanoparticle-forming the above-mentioned polymer materials. The additives used are not limited to one type, and multiple types of additives may be used.

[0035] The thickness of odor adsorption section 313 is sufficient as long as it is substantially 2 nm or more and 5 μm or less, and preferably 1 μm or less. Odor adsorption section 313 contains an adsorption component that exhibits unique adsorption properties for specific odor substances contained in the surrounding gas.

[0036] The detection unit 314 is an element that outputs the generated potential change as a signal. Note that the change caused by the odor adsorption unit 313 is not limited to a potential change, but may be a change in resistivity or impedance, or the element of the detection unit 314 may be a sensor that detects current. The element of the detection unit 314 may be, for example, a photoelectric conversion element, a FET sensor, or an ISFET sensor.

[0037] The odor sensor 300 may have a plurality of odor adsorption units 313. Each of the plurality of additives 317 in the plurality of odor adsorption units 313 may exhibit unique adsorption characteristics for a plurality of different odor substances, and the plurality of odor adsorption units 313 may be independently arranged on the surface of the detection unit 314. Here, "independently arranged" includes the plurality of odor adsorption units being arranged in any arrangement, such as a row or a grid.

[0038] <How to make an odor sensor> A method for producing an odor sensor 300 having an odor adsorption unit 313 and a detection unit 314 will be described. The method for producing the odor sensor 300 includes a film-forming step of forming a film of a base agent 315 on the detection unit 314, and an adding step of adding an additive 317 to the base agent 315 applied to the detection unit 314. The additive 317 has a size equal to or smaller than the pore size of the porous structure 316, and penetrates into the porous structure 316 of the base agent 315.

[0039] The size of porous structure 316 is preferably in the range of 0.5 nm to 500 nm. If the size of porous structure 316 is smaller than 0.5 nm, the additive may not penetrate into porous structure 316. If the size of porous structure 316 is larger than 500 nm, the porous structure 316 may become as large as the film thickness of odor adsorption section 313, which may increase the sparseness of odor adsorption section 313 and reduce its mechanical strength.

[0040] The additive 317 preferably has a size in the range of 0.1 nm to 500 nm. Most of the additives 317 are low-molecular-weight compounds, and the lower limit of the size of the additive 317 is a typical molecular size (0.1 nm to several nm). The pore size of the porous structure 316 is the upper limit of the size of the additive 317. Examples of the additive 317 include acids (hydrochloric acid, alkylsulfonic acid, etc.), salts (carboxylates, alkylsulfonates, ionic liquids, etc.), and self-organizing materials (liquid crystal molecules, etc.).

[0041] 5A and 5B are diagrams illustrating a method for fabricating the odor sensor 300 of Embodiment 1. In the film-forming step shown in FIG. 5B, an odor adsorption section 313 including a base agent 315 having a porous structure 316 is formed on a detection section 314 shown in FIG. 5A. In the adding step shown in FIG. 5C, an additive 317 is added. As a result, after the adding step, the additive 317 adheres to the surface of the base agent 315 and penetrates into the porous structure 316 of the base agent 315.

[0042] <Method 1 for producing a base agent having a porous structure> A method for producing a base agent 315 having a porous structure 316 (hereinafter referred to as porous structure production method 1) will be described. Porous structure production method 1 includes a mixing step and a first dissolving step before the above-mentioned film-forming step. The film-forming step includes a coating step and a second dissolving step. Note that porous structure production method 1 may include a drying step after the second dissolving step, in which the base agent 315 having the porous structure 316 formed therein is dried.

[0043] FIG. 6 is a schematic diagram illustrating the porous structure fabrication method 1. FIG. 6(a) is a schematic diagram illustrating the mixing step, FIG. 6(b) is a schematic diagram illustrating the first dissolving step, FIG. 6(c) is a schematic diagram illustrating the coating step, FIG. 6(d) is a schematic diagram illustrating the second dissolving step, and FIG. 6(e) is a schematic diagram illustrating the drying step. In the mixing step shown in FIG. 6(a), a base agent 315 (open triangle) and a resin 318 (filled circle) are mixed to prepare a mixture 319. Here, when the base agent 315 is a resin, the resin 318 is a different resin (second resin) from the first resin, assuming that the base agent 315 is the first resin. Note that only some components are labeled in FIG. 6(a). In the first dissolving step shown in FIG. 6(b), the mixture 319 is dissolved in a first solvent 320, which is a good solvent for the base agent 315 and the resin 318.

[0044] In the application process shown in FIG. 6(c), the mixture 319 dissolved in the first solvent 320 is applied to the detection unit 314. The application process can be performed using, for example, a spray gun, dispenser, coater, printer, etc., and the same applies to the other application processes described below. In the second dissolution process shown in FIG. 6(d), the resin 318 is dissolved in a second solvent 321, which is a poor solvent for the base agent 315 but a good solvent for the resin 318. In the second dissolution process, the second solvent 321 may be applied to the mixture 319 dissolved in the first solvent 320, or may be sprayed as shown. This results in a porous structure 316 being formed in the base agent 315. In the drying process shown in FIG. 6(e), the first solvent 320 and / or the second solvent 321 are removed by drying, resulting in an odor adsorption unit 313 containing the base agent 315 with the porous structure 316. The open triangle representing the base agent 315 is omitted from FIG. 6(e).

[0045] Here, the first solvent 320 being a good solvent for the base agent 315 and the resin 318 means that the first solvent 320 can dissolve both the base agent 315 and the resin 318 (soluble), and the first solvent 320 is also referred to as a co-solvent. The second solvent 321 being a poor solvent for the base agent 315 means that the second solvent 321 cannot dissolve the base agent 315 (insoluble). On the other hand, the second solvent 321 being a good solvent for the resin 318 means that the second solvent 321 can dissolve the resin 318. In this way, the base agent 315 is insoluble in the second solvent 321, but the resin 318 is soluble in the second solvent 321. By selectively dissolving the resin 318 in the mixture 319 with the second solvent 321 in this way, nanoscale pores are formed in the locations where the resin 318 was previously present.

[0046] Here, an example of base agent 315 is polyaniline, an example of resin 318 is polyethylene glycol, an example of first solvent 320 (co-solvent) is N-methylpyrrolidone (NMP), and an example of second solvent 321 (poor solvent) is water.

[0047] <Amount of Resin 318> The ratio of resin 318 to base agent 315 in the mixing process described in FIG. 6(a) will now be described. FIG. 7 is a schematic diagram showing the results of fabricating an odor adsorption unit by varying the amount of resin relative to the base agent. FIG. 7(a) is a schematic diagram showing odor adsorption unit 313a (odor sensor 300a) when the amount of resin 318 relative to the base agent 315 is small. FIG. 7(b) is a schematic diagram showing odor adsorption unit 313 (odor sensor 300) of embodiment 1 when the amount of resin 318 relative to the base agent 315 is appropriate. FIG. 7(c) is a schematic diagram showing odor adsorption unit 313b (odor sensor 300b) when the amount of resin 318 relative to the base agent 315 is large. Enlarged top view schematic diagrams of odor adsorption units 313, 313a, and 313b are shown below the white arrows in all figures.

[0048] As shown in FIG. 7(a), when the amount of resin 318 relative to the base agent 315 was less than the appropriate amount (predetermined amount), the base agent 315 became too dense, making it impossible to create a porous structure 316 that was continuous in the thickness direction (Dr). This made it difficult to add the additive 317 to the base agent 315. As shown in FIG. 7(c), when the amount of resin 318 relative to the base agent 315 was greater than the appropriate amount, the base agent 315 became too sparse, resulting in an uneven distribution of the base agent 315, and aggregates 315a of the base agent 315 formed, resulting in an uneven film. On the other hand, as shown in FIG. 7(b), when the amount of resin 318 relative to the base agent 315 was appropriate, a porous structure 316 that was continuous in the thickness direction (Dr) could be formed, resulting in an odor adsorption section 313 with an appropriate density. The amount of resin 318 added was 1 to 10 times the weight of the base agent 315.

[0049] <Method 2 for producing a base agent having a porous structure> A method for producing a base agent 315 having a porous structure 316 (hereinafter referred to as porous structure production method 2) will be described. Porous structure production method 2 includes a dissolving step before the above-mentioned film-forming step. The film-forming step includes a coating step and a deposition step. Note that porous structure production method 2 may also include a drying step after the deposition step, in which the base agent 315 having the porous structure 316 formed thereon is dried. Figure 8 is a diagram illustrating porous structure production method 2. Figure 8(a) is a schematic diagram showing the dissolving step, Figure 8(b) is a schematic diagram showing the coating step, Figure 8(c) is a schematic diagram showing the deposition step, and Figure 8(d) is a schematic diagram showing the drying step.

[0050] 8(a), the base agent 315 is dissolved in a third solvent 322 that is a good solvent for the base agent 315. The third solvent 322 is a solvent that can dissolve the base agent 315. Note that the above-mentioned first solvent 320 is also a good solvent for the base agent 315, so the first solvent 320 can be used as the third solvent 322.

[0051] In the application step shown in FIG. 8(b), the base agent 315 dissolved in a third solvent 322 is applied to the detection unit 314. In the deposition step shown in FIG. 8(c), the third solvent 322 containing the dissolved base agent 315 is replaced with a fourth solvent 323, which is a poor solvent for the base agent 315, to deposit the base agent 315. The fourth solvent 323 is a solvent that cannot dissolve the base agent 315. Note that the second solvent 321 described above is also a poor solvent for the base agent 315, and therefore the second solvent 321 can be used as the fourth solvent 323. In the drying step shown in FIG. 8(d), the third solvent 322 and / or the fourth solvent 323 are removed by drying, thereby obtaining the base agent 315 having a porous structure 316. Note that the open triangle representing the base agent 315 is also omitted in FIG. 8(d).

[0052] Here, an example of base agent 315 is polyaniline, an example of third solvent 322 (co-solvent) is N-methylpyrrolidone (NMP), and an example of fourth solvent 323 (poor solvent) is water.

[0053] <Replacement method> The third solvent 322 may be replaced with the fourth solvent 323, for example. The third solvent 322 containing the base agent 315 is applied to the detection unit 314 and left for a predetermined time in the space where the fourth solvent 323 has evaporated. This gradually replaces the third solvent 322 with the fourth solvent 323, causing the base agent 315 to slowly precipitate (sink). This allows the base agent 315 to have a porous structure 316. For example, if the base agent 315 is polyaniline, the third solvent 322 is a good solvent for polyaniline, and the fourth solvent 323 is water, leaving the third solvent 322 containing the base agent 315 in a high-humidity environment for a predetermined time can yield polyaniline with a porous structure 316. For example, the third solvent 322 is left in a humidity environment of 60% or higher for one day (a predetermined time). An example of the third solvent 322 (good solvent) is NMP.

[0054] Alternatively, for example, third solvent 322 containing dissolved base agent 315 is applied to detection unit 314, and vapor of fourth solvent 323 is applied to third solvent 322 containing dissolved base agent 315 for a predetermined time. As a result, third solvent 322 is replaced with fourth solvent 323, and porous structure 316 is formed in base agent 315. For example, if base agent 315 is polyaniline, third solvent 322 is a solvent that is a good solvent for polyaniline, and fourth solvent 323 is water, polyaniline having porous structure 316 can be obtained by applying water vapor to third solvent 322 containing dissolved base agent 315 for a predetermined time. For example, water vapor is applied to third solvent 322 for 10 minutes to 1 hour (predetermined time). Here, an example of third solvent 322 (good solvent) is NMP.

[0055] The method for forming the porous structure 316 in the base agent 315 is not limited to the above-described porous structure fabrication method 1 and porous structure fabrication method 2, and may be another method. For example, a method in which the base agent 315 is nanoparticled and deposited may also be applied.

[0056] Example 1 The odor adsorption section 313 of Example 1 was fabricated using porous structure fabrication method 1. Polyaniline was used as the base agent 315. Polyethylene glycol (PEG) was used as the resin 318. Polyethylene glycol is a polymer compound that is easily soluble in water (water-soluble). N-methylpyrrolidone was used as the first solvent 320. Water was used as the second solvent 321. Hydrochloric acid was used as the additive 317. A CMOS sensor was used as the detection section 314. In Example 1, a porous structure 316 was formed in the base agent 315, and an excellent odor adsorption section 313 was obtained.

[0057] <Example 2> The odor adsorption unit 313 of Example 2 was fabricated using Porous Structure Fabrication Method 1. Polyvinyl chloride (PVC) was used as the base agent 315. Polyethylene glycol (PEG) was used as the resin 318, as in Example 1. NMP was used as the first solvent 320. Water was used as the second solvent 321. An ionic liquid (imidazolium salt) was used as the additive 317. A CMOS sensor was used as the detection unit 314.

[0058] <Comparative Example 1 to Example 2> In Comparative Example 1, a base agent that does not have a porous structure 316 is applied onto the detection section 314. This is the same as Example 1 except that the base agent does not have a porous structure 316.

[0059] <Example 2 and Comparative Example 1> FIG. 9 illustrates the effects of embodiment 1. FIG. 9(a) shows a schematic top view of the odor adsorption unit 313 of Example 2, and FIG. 9(b) shows a schematic top view of the odor adsorption unit 313c of Comparative Example 1. In both cases, an enlarged schematic view of the upper view is shown below the white arrow. In Example 2 of FIG. 9(a), a porous structure 316 was formed, and it was confirmed as a microstructure. The microstructure made it difficult to see the detection unit 314 below the odor adsorption unit 313. Note that the microstructure is indicated by hatching in FIG. 9. In Example 2, when an additive 317 was added to the base agent 315, the additive 317 was able to penetrate into the porous structure 316.

[0060] On the other hand, in Comparative Example 1 in Figure 9(b), a uniform film of the base agent was formed, and the microstructure could not be confirmed. Because the microstructure could not be confirmed, the detection unit 314 below the odor adsorption unit 313c was visible. In the case of Figure 9(b), the additive 317 simply sat on the surface of the base agent and was unable to penetrate into the base agent.

[0061] Example 3 The odor adsorption unit 313 of Example 3 was fabricated using Porous Structure Fabrication Method 1. Polymethyl methacrylate (PMMA) (acrylic resin) was used as the base agent 315. As in Example 1, polyethylene glycol (PEG) was used as the resin 318. NMP was used as the first solvent 320. Water was used as the second solvent 321. An ionic liquid (imidazolium salt) was used as the additive 317. A CMOS sensor was used as the detection unit 314.

[0062] <Comparative Example 2 to Example 3> In Comparative Example 2, a base agent that does not have a porous structure 316 is applied onto the detection section 314. This is the same as Example 3, except that the base agent does not have a porous structure 316.

[0063] <Example 3 and Comparative Example 2> Figure 9(c) shows a schematic top view of the odor adsorption unit 313 of Example 3, and Figure 9(d) shows a schematic top view of the odor adsorption unit 313d of Comparative Example 2. In both cases, an enlarged schematic view of the upper view is shown below the white arrow. In Example 3 of Figure 9(c), a porous structure 316 was formed, which could be confirmed as a fine structure. The fine structure made it difficult to see the detection unit 314 below the odor adsorption unit 313. In Example 3, when an additive 317 was added to the base agent 315, the additive 317 was able to penetrate into the porous structure 316.

[0064] On the other hand, in Comparative Example 2 shown in Figure 9(d), a uniform film of the base agent was formed, and the microstructure could not be confirmed. Because the microstructure could not be confirmed, the detection unit 314 below the odor adsorption unit 313d was visible. In the case of Figure 9(d), the additive 317 simply sat on the surface of the base agent and was unable to penetrate into the base agent.

[0065] As described above, according to embodiment 1, it is possible to provide a method for manufacturing an odor sensor and an odor sensor that can increase the degree of freedom in the combination of the main agent and additives used in the odor adsorption section without reducing the detection accuracy of the odor sensor.

[0066] [Embodiment 2] The odor sensor according to the second embodiment will be described below.

[0067] <Configuration of odor sensor> In odor sensors, an adsorption film that adsorbs specific odor substances is formed on the surface of the base. The adsorption film is formed by adding an additive to a film material such as a conductive polymer film.

[0068] A quartz crystal microbalance (QCM) sensor can also be used as the base. Other sensors that can be used include surface acoustic wave sensors, field effect transistors (FETs), charge-coupled device sensors, metal oxide semiconductor sensors, organic conductive polymer sensors, electrochemical sensors, piezoelectric sensors, and SPR sensors. Depending on the base, the physical quantities that make up the odor data F1 can include frequency, electric potential, mass, wavelength and intensity of light or sound, resistance, and current.

[0069] Examples of the film material that can be used to form the adsorption film include conductive polymers, including conductive resins such as polyaniline, polypyrrole, and polythiophene. Ionic liquids, general-purpose resins, plasticizers, and salts can also be used as the film material. Inorganic materials such as gold, silver, platinum, chromium, titanium, aluminum, nickel, nickel-based alloys, and silicon can be used for the electrodes. Other examples of nanocarbon materials that can be used include carbon, carbon nanotubes, and graphene.

[0070] Examples of additives that can be used include inorganic ions, organic acid anions, and polymeric acid anions. Examples of inorganic ions include chloride ions, chlorine oxide ions, bromide ions, sulfate ions, nitrate ions, and borate ions. Examples of organic acid anions include alkylsulfonic acid, benzenesulfonic acid, and carboxylic acid. Examples of polymeric acid anions include organic acid anions such as alkylsulfonic acid, benzenesulfonic acid, and carboxylic acid, and polymeric acid anions such as polyacrylic acid and polystyrenesulfonic acid. Other examples of additives include host materials such as cyclodextrin and crown ether derivatives, organic base materials such as alkylamines, arylamines, and nitrogen-containing heterocyclic compounds, and hydrogen-bonding materials such as urea derivatives and thiourea derivatives. Various ionic liquids can also be used as additives.

[0071] <Odor sensor array> The odor sensor can be used by arranging multiple adsorption membranes on the surface of one or multiple bases. In this case, for example, multiple adsorption membranes with unique adsorption properties for different odor substances can be arranged in a row. Also, multiple adsorption membranes can be aligned in a plane, with multiple membranes arranged vertically and horizontally.

[0072] By using information about the order in which the adsorption films have been arranged and which have which adsorption properties as an encryption key or passcode, security can be enhanced in various situations. This odor sensor or the entire system including it can be used as a security system that utilizes odors.

[0073] <Odor database confidentiality processing> 10 is a schematic diagram of an odor sensor unit 1010 according to a second embodiment. The odor sensor unit 1010 has five odor sensors 1010a to 1010e. The odor sensors 1010a to 1010e use, for example, a quartz crystal microbalance sensor (QCM) as the base 1002. In this second embodiment, the five odor sensors 1010a to 1010e are arranged in a row. Adsorption films 1004a to 1004e are formed on the surfaces of the five bases 1002, respectively, and the adsorption films 1004a to 1004e correspond to the odor sensors 1010a to 1010e, respectively. The adsorption films 1004a to 1004e are formed by adding additives 1006a to 1006e to a conductive polymer film 1005, respectively. Due to the differences in the properties of the additives 1006a to 1006e, the adsorption films 1004a to 1004e exhibit the adsorption properties of adsorbing different odor substances.

[0074] Assume that odors of three types of gases Ga, Gb, and Gc are detected by this odor sensor 1010 and stored in database DB1. The detection results when the gases Ga, Gb, and Gc are detected by odor sensors 1010a to 1010e are, for example, as follows. The values ​​in parentheses are the output values ​​of odor sensors 1010a to 1010e, respectively. Gas Ga: (0,5,10,5,0) Gas Gb: (2, 4, 6, 8, 10) Gas Gc: (10,8,6,4,2)

[0075] If these output values ​​were stored as is in the odor database DB, then if the information in the odor database DB were to be stolen, the detection results of the odor sensors 1010a-1010e for gases Ga-Gc would easily be revealed to the pirate. However, for example, if the arrangement order of the output values ​​of the five odor sensors 1010a-1010e were changed, and the output values ​​from the odor sensors 1010a-1010e were stored in the changed arrangement order in the odor database DB. If the information on this changed order were then used as an encryption key and managed separately from the odor database DB, then even if the information in the database DB were to be stolen, the pirate would not be able to easily ascertain the detection results of the odor sensors 1010a-1010e for gases Ga-Gc.

[0076] For example, if the output values ​​of the five odor sensors 1010a to 1010e are arranged in the order (1, 3, 5, 2, 4), the detection results of the gases Ga to Gc stored in the odor database DB will be as follows: Gas Ga: (0,10,0,5,5) Gas Gb: (2,6,10,4,8) Gas Gc: (10,6,2,8,4)

[0077] Without the encryption key, the detection results of gases Ga to Gc by the odor sensors 1010a to 1010e cannot be reproduced in the correct order of the sensors. Here, by using the encryption key (1, 3, 5, 2, 4), the detection results of gases Ga to Gc in the odor database DB can be decrypted in the correct order of the odor sensors 1010a to 1010e. This measure improves the security of the odor data stored in the odor database DB.

[0078] Furthermore, for example, the order of the sensors in an odor sensor unit for detecting odor data to be stored in the odor database DB can be changed from the order of the sensors in an odor sensor unit sold to users, and the change can be used as an encryption key. Furthermore, when producing multiple odor sensor units, changing the sensor arrangement in each unit or for each batch and managing the change as an encryption key can further contribute to improving the confidentiality of odor data.

[0079] <Access control using scent> By using the odor sensor unit 1010 shown in FIG. 10, it is possible to realize, for example, room entry / exit management using odors. Locking and unlocking of rooms is performed using gases with specific odors. Here, the odor used for room entry / exit is referred to as an "odor key." The odor key may be, for example, a specific perfume or an individual's body odor. By linking the odor sensor unit 1010 to an entry / exit control system that controls the locking and unlocking of room doors, it is possible to unlock the door using the odor key.

[0080] Here, for example, a configuration can be made in which the door cannot be unlocked with just the smell key, but can only be unlocked by inputting the sensor array information in the smell sensor unit 1010 as a password. For example, the detection result that can unlock the door is (2, 4, 6, 8, 10), and this information is stored in a database or the like in the access control system or in the cloud. If the detection result of the smell key by the smell sensor unit 1010 is (2, 6, 10, 4, 8), the door cannot be unlocked. However, when the sensor array information (1, 3, 5, 2, 4) in the smell sensor unit 1010 is input, the detection result of (2, 6, 10, 4, 8) is converted to (2, 4, 6, 8, 10). The converted detection result is compared with the detection result stored in the database or the like, and if they match, the door can be unlocked.

[0081] <Industrial Applicability> Furthermore, by using the odor sensor described in the above embodiment and the method for analyzing odor data detected by the odor sensor, it is possible to quickly and accurately identify the odor substance contained in a gas containing multiple different odor substances. The load on the processing device can also be reduced. Even when distinguishing the odor of a specific gas from that of other gases, rapid and accurate discrimination is possible. Furthermore, when identifying odor substances contained in a detected gas by comparing the detected odor data with odor data stored in a database, etc., rapid and accurate matching is possible.

[0082] Note that the odor sensors 1010a to 1010e of Embodiment 2 can be replaced with the odor sensor 300 of Embodiment 1. In this case, even in Embodiment 2, it is possible to provide an odor sensor and a method for manufacturing an odor sensor that can increase the degree of freedom in the combination of the base agent and additives used in the odor adsorption section without reducing the detection accuracy of the odor sensor.

[0083] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these and various modifications and changes are possible within the scope of the gist of the present invention. For example, the present invention includes the following aims. (Objective 1) A method for producing an odor sensor having an odor adsorption portion and a base portion, comprising: The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, a film-forming step of forming a film of the base material on the base; an adding step of adding the additive to the base material applied to the base; and A method for producing an odor sensor, wherein after the adding step, the additive penetrates into the nanoporous structure of the base material. (Objective 2) Before the film forming step, a mixing step of mixing the base agent and a resin to prepare a mixture; a first dissolving step of dissolving the mixture in a first solvent that is a good solvent for the base agent and the resin; and The film forming step includes: a coating step of coating the mixture dissolved in the first solvent onto the base; a second dissolving step of dissolving the resin in a second solvent that is a poor solvent for the base resin and a good solvent for the resin; may have (Objective 3) Before the film forming step, a dissolving step of dissolving the main component in a third solvent that is a good solvent for the main component, The film forming step includes: a coating step of coating the base with the main agent dissolved in the third solvent; a precipitating step of replacing the third solvent in which the main component is dissolved with a fourth solvent that is a poor solvent for the main component, thereby precipitating the main component; may have (Objective 4) The base material may be a resin. (Objective 5) The base resin may be polyvinyl chloride, polymethyl methacrylate, polyvinylidene fluoride, cycloolefin polymer, polybutyl methacrylate, polyethylene glycol, polyvinyl alcohol, or a copolymer of these resins. (Objective 6) The base material may be a conductive polymer. (Objective 7) The conductive polymer may be a group of conductive resins including polyaniline, polypyrrole, and polythiophene. (Objective 8) An odor sensor having an odor adsorption portion and a base portion, The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, An odor sensor, wherein the additive is infiltrated into the nanoporous structure of the base material. (Objective 9) The base material may be a resin. (Objective 10) The base resin may be polyvinyl chloride, polymethyl methacrylate, polyvinylidene fluoride, cycloolefin polymer, polybutyl methacrylate, polyethylene glycol, polyvinyl alcohol, or a copolymer of these resins. (Objective 11) The base material may be a conductive polymer. (Objective 12) The conductive polymer may be a group of conductive resins including polyaniline, polypyrrole, and polythiophene. [Explanation of symbols]

[0084] 100 Odor Sensor 110, 110a to 110l sensor element 112, 112a~112l adsorption membrane 114, 114a to 114l detection unit 116, 116a~116l electrode 120 board, 120a, 120b side 200 Data analysis equipment 220 Analysis Department 220a CPU, 220b storage device (memory), 220c input / output port 300, 300a, 300b odor sensors 313, 313a-313d Odor absorption section 314 Detection unit 315 Base Agent, 315a Aggregate 316 Porous Structure 317 Additives 318 Resin 319 Mixture 320 First solvent, 321 Second solvent, 322 Third solvent, 323 Fourth solvent 1002 base 1004a~1004e Adsorption film 1005 Conductive polymer film 1006a~1006e Additives 1010 Odor sensor unit 1010a~1010e Odor sensors DB, DB1 database Dr thickness direction F1 Smell Data Ga~Gc gas P analysis program R Calculated Data

Claims

1. A method for producing an odor sensor having an odor adsorption portion and a base portion, comprising: The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, a film-forming step of forming a film of the base material on the base; an adding step of adding the additive to the base material applied to the base; and A method for producing an odor sensor, wherein after the adding step, the additive penetrates into the nanoporous structure of the base material.

2. Before the film forming step, a mixing step of mixing the base agent and a resin to prepare a mixture; a first dissolving step of dissolving the mixture in a first solvent that is a good solvent for the base agent and the resin; and The film forming step includes: a coating step of coating the mixture dissolved in the first solvent onto the base; a second dissolving step of dissolving the resin in a second solvent that is a poor solvent for the base resin and a good solvent for the resin; The method for producing the odor sensor according to claim 1 , comprising:

3. Before the film forming step, a dissolving step of dissolving the main component in a third solvent that is a good solvent for the main component, The film forming step includes: a coating step of coating the base with the main agent dissolved in the third solvent; a precipitating step of replacing the third solvent in which the main component is dissolved with a fourth solvent that is a poor solvent for the main component, thereby precipitating the main component; The method for producing the odor sensor according to claim 1 , comprising:

4. The method for producing an odor sensor according to claim 1 , wherein the main component is a resin.

5. 2. The method for producing an odor sensor according to claim 1, wherein the base material is polyvinyl chloride, polymethyl methacrylate, polyvinylidene fluoride, cycloolefin polymer, polybutyl methacrylate, polyethylene glycol, polyvinyl alcohol, or a copolymer of these resins.

6. The method for producing an odor sensor according to claim 1 , wherein the main agent is a conductive polymer.

7. 7. The method for producing an odor sensor according to claim 6, wherein the conductive polymer is a conductive resin group including polyaniline, polypyrrole, and polythiophene.

8. An odor sensor having an odor adsorption portion and a base portion, The odor adsorption section has a base material having a nanoporous structure that is continuous in the thickness direction of the odor adsorption section, and an additive added to the base material, and generates a change in electrical characteristics when an odor substance is adsorbed to the additive and when it is not adsorbed to the additive; the base is an element that outputs the change in electrical characteristic as a signal, An odor sensor, wherein the additive is infiltrated into the nanoporous structure of the base material.

9. The odor sensor according to claim 8 , wherein the base material is a resin.

10. 9. The odor sensor according to claim 8, wherein the base resin is polyvinyl chloride, polymethyl methacrylate, polyvinylidene fluoride, cycloolefin polymer, polybutyl methacrylate, polyethylene glycol, polyvinyl alcohol, or a copolymer of these resins.

11. The odor sensor according to claim 8 , wherein the main agent is a conductive polymer.

12. The odor sensor according to claim 11 , wherein the conductive polymer is a conductive resin group including polyaniline, polypyrrole, and polythiophene.

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