Odor cells that capture odor molecules

Abstract

To analyze odor molecules using a terahertz spectrometer or similar device, we provide an odor cell capable of quickly capturing a large number of odor molecules and retaining them for a certain period of time. [Solution] The odor cell 1 comprises a porous member 3 made of porous glass having numerous pores 4 on its surface and inside, and a ceramic member 2 made of fine protrusions such as whiskers, which are coated on the surface of the porous member 3 and the inner surface of the pores 4 near the surface with zinc oxide coated by open-air CVD and / or carbon nitride coated with ECR plasma CVD, thereby forming an odor molecule trapping structure and a catching structure.

Description

Technical Field

[0001] The present invention relates to an odor cell for capturing odor molecules, which is used in a spectroscopic apparatus capable of analyzing trace amounts of odor molecules contained in a gas.

Background Art

[0002] Conventionally, as a method for performing component analysis, structural analysis, and quantification of a sample by irradiating a substance with electromagnetic waves and measuring the transmitted or reflected electromagnetic waves, spectroscopic methods using ultraviolet light, visible light, and infrared light are known, and spectroscopic apparatuses (analytical apparatuses) to which this spectroscopic method is applied are widely used. In recent years, in addition to these, a new spectroscopic method called terahertz time-domain spectroscopy (THz-TDS), which uses electromagnetic waves in the frequency range of 0.1 to 10 THz, has also emerged. In the future, spectroscopic apparatuses applying this spectroscopic method are expected to be used as advanced analytical apparatuses in a wide range of fields such as materials, food, and medical fields.

[0003] For example, an analytical apparatus for analyzing a gas using terahertz waves or infrared light is disclosed in Patent Document 1. In this Document 1, it is shown that a capture film for capturing a gas is separated from a site (such as skin) that generates the gas, and the gas captured by this capture film is made to interact with terahertz waves or infrared light for analysis. And this capture film is a porous polymer, and materials with small losses in terahertz waves, for example, polymer-based porous materials such as polyethersulfone, nylon, polypropylene, polysulfone, Teflon (registered trademark), polyolefin, polyethylene, polystyrene, and ethylene tetrafluoride are mentioned. The pores inside this porous material are connected to each other, and generally, such a material is sometimes referred to as a sponge-shaped material. Also, the average diameter of the pores of such a porous material is desirably, for example, several tens of μm or less, which is sufficiently smaller than the wavelength of terahertz waves when using terahertz waves.

[0004] Furthermore, in the medical field, for example, Patent Document 2 discloses a special porous layer in which the target of analysis can be selected and / or concentrated at the sampling stage by using a porous adsorption layer with a pore size suitable for the adsorption of molecules, bacteria, viruses, and cells. The adsorption layer further discloses a special porous layer in which at least three porous layers with different central pore sizes are stacked in order of decreasing average pore size from 0.1 to 1000 nm from the sampling side. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-169658 [Patent Document 2] International Publication No. WO2012 / 056729 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, even when using capture membranes or capture layers that combine multiple types of porous polymer materials as described above, it is often impossible to capture a sufficient amount of the minute odor molecules (gas molecules) to be analyzed contained in the gas, or if it is possible, it takes a long time. Furthermore, once captured, the odor molecules cannot be retained and diffuse and disappear over time, often resulting in problems that prevent high-precision measurement and analysis.

[0007] The object of the present invention is to provide an odor cell having an odor molecule trapping structure and a catching structure that can capture a large amount of trace amounts of odor molecules contained in a gas more quickly than conventional methods, and can retain the captured odor molecules without letting them escape. [Means for solving the problem]

[0008] According to the following disclosure, an odor cell for capturing odor molecules used in a spectrometer capable of analyzing the components of odor molecules comprises a porous member having a large number of pores on its surface and inside, and a ceramic member coated on the surface of the porous member and on the inner surface of the pores near the surface, and the odor molecules are captured by the ceramic member and the pores of the porous member.

[0009] Furthermore, according to other disclosures, the ceramic members are composed of zinc oxide and / or carbon nitride. The shapes of these ceramic members are composed of at least one of the following shapes: whisker shape, column shape, or mountain shape.

[0010] Furthermore, according to other disclosures, the porous member is composed of at least one material, which is porous glass, zeolite, mesoporous silica, or a porous coordination polymer. [Effects of the Invention]

[0011] According to the following disclosure, it is possible to provide an odor cell having a unique trap structure and a catching structure that can capture a large number of odor molecules contained in trace amounts of gas more quickly than conventional methods, and that can retain the captured odor molecules without letting them escape. [Brief explanation of the drawing]

[0012] [Figure 1] This is an external view of an odor cell according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view of an odor cell according to an embodiment of the present invention. [Figure 3] This is a cross-sectional view showing the types of shapes of the ceramic members of the odor cell according to an embodiment of the present invention. [Modes for carrying out the invention]

[0013] (Scent Cell) Figure 1 is an external view of an odor cell 1 according to a preferred embodiment of the present invention. Figure 2 is a cross-sectional view of the odor cell 1 shown in Figure 1. However, for the sake of clarity of explanation, Figure 2 is a schematic diagram that magnifies only the surface of the odor cell 1 and a very small portion of the area near the surface. The odor cell 1 is constructed using a porous member 3 having a large number of pores 4 as a base material. The average size of these pores 4 is set to 50 nm, but it is not limited to this, and it is desirable to select the optimal size each time depending on the size of the odor molecule to be analyzed and whether or not it is in a so-called hydrated state with water molecules attached around it. The odor cell 1 is a roughly square plate with sides of about 5 to 30 mm and a thickness of about 1 to 6 mm, but it is not limited to this size and shape, and it is desirable to select the optimal size according to the size of the cell that can accommodate a terahertz spectrometer or infrared spectrophotometer. The shape of the odor cell 1 may be circular, or it may be a rectangular parallelepiped with some thickness.

[0014] The porous member 3 is preferably made of porous glass. Generally, this porous glass is composed of approximately 96% silicon dioxide (SiO2), has heat resistance similar to quartz glass, and is also an extremely stable material against organic solvents. For example, if the average size of the pores 4 of the porous member 3 made of this porous glass is set to 50 nm as described above, the bulk density is 1.12 g / cc, the void ratio is 49.1%, and the internal surface area is 80 m². 2 The density is / g, and the total surface area of ​​the pores 4 that capture odor molecules 5 is very large. Furthermore, numerous pores 4 are interconnected within the porous material 3, creating a structure that allows gas to easily permeate the entire material. Currently, a technology has been established that allows for the free setting of pore sizes in the range of 4 nm to several μm, so it is possible to appropriately select the pore diameter size according to the size of the gas molecules to be analyzed.

[0015] In the manufacturing method of such porous glass, a uniform glass is separated into multiple phases by heat treatment, and only the soluble phase is eluted with chemicals, thereby forming numerous pores. Porous glass is being actively researched by various researchers in the fields of microfiltration, ultrafiltration, and separation modes that utilize molecular flow in gas separation. The excellent properties of such porous glass, such as high gas permeability and light transmittance, are particularly advantageous for analyzing the components of odor molecules using terahertz time-domain spectroscopy (THz-TDS) with terahertz gas sensing (THGS) technology, such as the TeraProspector terahertz spectrometer (TeraProspector is a registered trademark of NIPPO Precision Co., Ltd.) from NIPPO Precision Co., Ltd. Furthermore, materials with pores, not just porous glass, act to sieve gas molecules such as odor molecules into large and small molecules according to their effective diameter. That is, small molecules can penetrate deep into the support, while molecules larger than the pores cannot penetrate into the support. Thus, the difference in apparent stationary phase volume due to sample size makes sieving possible.

[0016] Furthermore, as shown in Figures 1 and 2, ceramic members 2 made of zinc oxide (ZnO) are deposited on the surface of the porous member 3 and on the inner surface of the pores 4 near the surface using an open-air CVD apparatus equipped with an open-air chemical vapor deposition method. This zinc oxide ceramic member 2 is generally called an oxide film or ceramic coating, but from a microscopic perspective, in this embodiment it has a whisker-like shape. More specifically, when fabricating using the open-air CVD apparatus described above, it is possible to prepare 99% pure Zn(C5H7O2)2 (manufactured by Koshu Chemical Laboratory), set the vaporization temperature to 120 °C, the N2 carrier gas flow rate to 1.2 L / min, and the substrate temperature to 550 °C, and deposit it on a porous glass substrate which is the porous member 3. This open-air CVD method has the excellent characteristic of being able to produce oxide films with very few impurities and crystal defects. Furthermore, by appropriately selecting raw materials and crystal growth conditions, a predetermined shape can be achieved, for example, a width of 100-700 nm, an angle of 5°-60°, and a linear density of 1.0-5.0 × 10⁻¹⁰. 4 mm 3 Within this range, it is possible to form an oxide structure composed of zinc oxide and various other materials.

[0017] The above-described atmospheric open-type CVD apparatus has excellent characteristics in that it can be operated at a low cost and relatively easily synthesize an oxide thin film compared to other types of CVD apparatuses. That is, in the atmospheric open-type CVD method, after the source gas is ejected from the nozzle, it is transported to the surface of the target substrate, where the source gas generates reaction intermediate species by a gas-phase reaction, and while repeating adsorption and desorption on the substrate surface, atoms are regularly arranged by surface migration, thereby enabling crystal precipitation with few defects. In addition, since the raw material is in a gaseous state, it is possible to uniformly form a film on the fine irregularities on the surface of the target substrate, and a secondary effect of exhibiting good step coverage can also be obtained. Also, there is an advantage that the possibility of contamination by substances other than the film material is lower compared to smoothing methods such as mechanical polishing and etching. For these reasons, the ceramic member 2 such as zinc oxide (ZnO) in the embodiment according to the present invention is preferably manufactured by an atmospheric open-type CVD apparatus.

[0018] Next, the trap structure will be described using FIG. 2. First, a gas (gas) containing odor molecules 5 to be analyzed is blown around the porous member 3, or these odor molecules 5 fly toward the porous member 3 and the ceramic member 2 by Brownian motion. Then, the odor molecules 5 pass through the spaces between the fine protrusions made of the ceramic member 2 at a certain ratio and enter the inside of the pores 4, and are trapped in the trap structure 7 constituted by the ceramic member 2 and the pores 4. Once the odor molecules 5 that have entered the trap structure 7 encounter the fine protrusions as an obstacle, it becomes difficult for them to escape from the pores 4. On the contrary, on the inner surface of the pores 4 that connect deeper from the pores 4 near the surface, the obstacles of these ceramic members 2 have a lower density and a smaller size than near the surface, so it is relatively easier to enter deeper. As a result, the trapped odor molecules 5 move to the deeper-connected pores 4, and as a result, they are retained in the trap structure 7 for a longer time.

[0019] Thus, by modifying the surface of the porous member 3 having a large number of pores 4 and the inner surfaces of the pores 4 near the surface with a ceramic member 2 having fine protrusions such as whisker shapes of zinc oxide (ZnO) by the atmospheric pressure CVD method, it is possible to fabricate an odor cell 1 having a unique trap structure 7 capable of capturing odor molecules 5.

[0020] Next, the catching structure will be described. As shown in Fig. 2, when odor molecules 5 fly onto the surface of the odor cell 1, they enter and are captured in the forest where the whisker shapes of the ceramic member 2 are dense. By appropriately setting the shape and line density of the fine protrusions such as the whisker shapes of the ceramic member 2 according to the size of the odor molecules 5 to be captured, the odor molecules 5 can be directly captured by sandwiching or adhering them with the catching structure 6 composed of the fine protrusions of the ceramic member 2. Also, when the odor molecules 5 are relatively large in size, the contact area becomes relatively wide in the shallow depression part (valley part of the mountain shape) composed of the fine protrusions, so the odor molecules 5 are likely to adhere. Therefore, the shape of the ceramic member 2 functions similarly even if it is (a) a whisker shape, (b) a column shape, or (c) a mountain shape (or mountain range shape) as shown in Fig. 3.

[0021] As described above, such a trap structure 7 for capturing odor molecules 5 and a catching structure 6 aim to obtain a sieving effect based on the Knudsen diffusion theory occurring in the pores 4, and at the same time aim to obtain a surface modification effect based on the linear solvation energy relationship (LSER) theory.

[0022] Odor cell 1 was manufactured primarily for the purpose of analyzing the components of captured odor molecules 5 by setting it in a spectrometer or spectrophotometer. In particular, with the aim of making it function effectively in terahertz spectrometers, zinc oxide (ZnO) was selected as the material used for surface modification, focusing on the transmittance of terahertz waves. Furthermore, by arranging these zinc oxide ceramics in a whisker shape, we proposed odor cell 1 with its unique trap structure 7 and catching structure 6. While terahertz waves or infrared light are preferable for the electromagnetic waves of a spectrometer used to analyze the components of odor molecules 5, this does not exclude spectrophotometers that use ultraviolet or visible light. The wavelengths of electromagnetic waves used by spectrometers and spectrophotometers that can utilize this odor cell 1 are 200 nm to 2000 nm, meaning that infrared, visible, and ultraviolet light can also be targeted.

[0023] Furthermore, compared to conventional simple porous materials or combinations of multiple porous layers with different central pore diameters, such as the porous layers 121-125 in Patent Document 2, the above-described embodiment, despite having a relatively simple structure, is capable of capturing more odor molecules 5 in a shorter time than conventional methods, through the trap structure 7 within the pores 4 and the direct catching structure 6 by the ceramic member 2. Moreover, it has the excellent effect of being able to retain the captured odor molecules 5 for a longer period of time than conventional methods. This improves responsiveness by shortening the time required for component analysis, structural analysis, and quantification of odor molecules 5 using spectroscopic analyzers and spectrophotometers that utilize terahertz waves or infrared light, and also has the excellent effect of improving the sensitivity of the analysis from the conventional ppm level to the ppb level.

[0024] Furthermore, the material of the ceramic member 2 in the above embodiment may be carbon nitride (CNx) instead of zinc oxide (ZnO). In this case, the ceramic member 2 can be manufactured by depositing carbon nitride on the porous member 3 using ECR plasma CVD. The shape can also be any of the shapes shown in Figure 3, similar to zinc oxide: (a) whisker shape, (b) cylindrical shape, or (c) mountain shape (mountain range shape).

[0025] Furthermore, it is also possible to construct the ceramic member 2 by first depositing zinc oxide (ZnO) onto the porous member 3 using open-air CVD, and then forming a carbon nitride (CNx) film using ECR plasma CVD. In this case, the efficiency of capturing odor molecules 5 is further improved, and because the carbon nitride film is very hard, it also functions as a protective film that prevents deterioration such as wear and oxidation of the zinc oxide. Therefore, this has the effect of improving the durability and extending the lifespan of the odor cell 1.

[0026] As described above, porous glass made of glass is preferred as the porous member 3, but the material is not limited to this, and any material that is transparent to electromagnetic waves used for analysis, such as terahertz waves and infrared light, can be used as a substitute. For example, zeolite having regular channels (tubular pores) and cavities, mesoporous silica (MS) having a structure in which pores are regularly aligned, and porous coordination polymers (PCP) / metal-organic frameworks (MOF) can also be applied. Although porous materials alone have some function in capturing odor molecules, by coating the surface of these porous materials and the inner surface of the pores near the surface with the ceramic member of the above embodiment, it becomes possible to manufacture an odor cell that captures odor molecules more efficiently.

[0027] According to the IUPAC (International Union of Pure and Applied Chemistry) definition, porous materials are classified into three categories based on the diameter of their pores: (1) micropores if the pore diameter is 2 nm or less, (2) mesopores if the pore diameter is between 2 nm and 50 nm, and (3) macropores if the pore diameter is 50 nm or larger. For example, the above-mentioned PCP has a pore diameter of approximately 0.4 nm to 6 nm, offering a wide variety of options in the micropore to mesopore range, and it is possible to select any pore size from this range and apply it to the porous material 3 of this embodiment. As such, there are many types of porous materials that are transparent to electromagnetic waves such as terahertz waves and infrared light, and therefore, it is possible to freely select the optimal material by comprehensively considering factors such as the size and chemical properties of the odor molecules to be analyzed, the operating environment of the spectrometer or spectrophotometer, the pore size, processability, and cost. [Explanation of symbols]

[0028] 1…Scent cell 2…Ceramic components 3…Porous material 4…Pores 5… Odor molecules 6…Catching structure 7…Trap structure

Claims

1. In an odor cell used in a spectroscopic instrument capable of analyzing the components of odor molecules, A porous member having numerous pores on its surface and inside, This comprises a ceramic member coated on both the surface of the porous member and the inner surface of the pores near the surface, A scent cell characterized by capturing odor molecules through both the ceramic component and the pores.

2. The odor cell according to claim 1, wherein the ceramic member is composed of zinc oxide or carbon nitride.

3. The odor cell according to claim 1, wherein the ceramic member is composed of zinc oxide and carbon nitride coated on the zinc oxide.

4. The odor cell according to claim 2 or 3, wherein the ceramic member is composed of at least one shape of a whisker, a column, or a mountain shape.

5. The odor cell according to claim 1, wherein the porous member is made of at least one of the following materials: porous glass, zeolite, mesoporous silica, or porous coordination polymer.

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