JP7145777B2 - sensor - Google Patents

Description

The present invention relates to sensors.

Sensors generally have a sensing portion (receptor) that enables highly sensitive and selective detection of the analyte of interest. A wide variety of substances such as self-assembled membranes, monolayers, DNA/RNA, proteins, antigens/antibodies, and polymers are used as receptors. Due to the recent development of AI and IoT in the olfactory/gas sensor field, new applications are expected in the future. In recent years, the disposal of fruits and vegetables due to over-maturity of foods during the food transportation process has been recognized as a major global problem. In the process of ripening fruits and vegetables, specific gases such as ethylene, ethanol, and acetaldehyde are emitted. In particular, tracking of ethanol and aldehyde derived from anaerobic respiration of food is important when controlling food quality with sensors.

In Patent Document 1, a porous material or a granular material is coated on a sensor body of a type that detects a physical parameter, and the specimen molecules are adsorbed by the porous material or the granular material. A sensor for detecting molecules is described.

In Patent Document 2, a sensor body that detects changes in physical parameters, and a receptor layer that contains fine particles with a particle size of 1 mm or less modified with a hydrocarbon group and covers the surface of the sensor body. Fuel oil identification. A sensor is described.

In Patent Document 3, a quartz crystal microbalance (QCM) gas sensor that detects VOC gas by utilizing the adsorption properties of a target gas to be measured and layered inorganic compound particles, wherein an organic residue is present between the layers of the layered inorganic compound. describes a gas sensor characterized by having a structure in which porous organic-inorganic hybrid particles in which is inserted and fixed are stacked as a detection film on a crystal oscillator electrode.

WO2016/121155 WO2017/098862 JP 2011-080983 A

Although the technology described in Patent Document 1 achieves high sensitivity, selectivity, and stability, the electrical signal is greatly attenuated except in a dry atmosphere, and the environment in which it can be used as an olfactory sensor is greatly limited. 2, the analyte is limited to highly hydrophobic gases.

The technique described in Patent Document 3 realizes a VOC gas sensor with good response recovery and reproducibility. is inhibited, and it cannot be used reproducibly except under limited drying conditions.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to enable measurement of highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under humid conditions. Another object of the present invention is to provide a sensor capable of continuous measurement without deterioration of the sensitive film even after reflow treatment and long-term use.

In order to solve the above-mentioned problems, the inventors of the present application have made earnest studies and repeated experiments.

That is, the present invention includes the following aspects.
[1]
A sensor having a sensitive membrane comprising an organic-inorganic hybrid,
The organic-inorganic hybrid comprises a structure represented by _RSiO3/2 , wherein R represents an organic functional group;
The sensor, wherein the porosity as a volume fraction of the sensitive film is 10% or less.
[2]
The sensor according to [1], wherein the porosity is 5% or less.
[3]
The sensor according to [1] or [2], wherein the porosity is 3% or less.
[4]
The sensor according to any one of [1] to [3], wherein the sensitive film further contains a filler.
[5]
The sensor according to [4], wherein the filler is an inorganic filler.
[6]
The sensor according to [4] or [5], wherein the filler is a metal oxide.
[7]
The sensor according to any one of [4] to [6], wherein the filler is silica.
[8]
The sensor according to any one of [4] to [7], wherein the shape of the filler is spherical or chain.
[9]
The sensor according to any one of [1] to [8], wherein the organic functional group contains an aromatic ring.
[10]
The sensor according to any one of [1] to [9], wherein the aromatic ring is directly bonded to a Si atom in the organic-inorganic hybrid.
[11]
The sensor according to any one of [1] to [10], wherein the organic functional group includes a copolymer structure of an aromatic ring and a non-aromatic ring structure.
[12]
The sensor according to any one of [1] to [11], wherein the organic functional group contains at least one selected from the group consisting of halogen atoms, nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms and boron atoms. .
[13]
The sensor according to any one of [1] to [12], wherein the organic functional group content in the organic-inorganic hybrid is 75% by weight or less.
[14]
The sensor according to any one of [1] to [13], wherein the organic functional group content in the organic-inorganic hybrid is 65% by weight.
[15]
The sensor according to any one of [1] to [14], wherein the sensitive film has a maximum thickness of 30 μm or less.
[16]
The sensor according to any one of [1] to [15], which is a surface stress sensor.

According to the present invention, highly hydrophilic gases such as ethanol and aldehyde can be measured with high sensitivity even under humid conditions. It is possible to provide a sensor that can continuously measure without deterioration of

An example of an optical microscope photograph of a chip coated with a sensitive film is shown. 4 is a surface SEM image of the sensitive film of Example 1. FIG. 1 is a cross-sectional SEM image of Example 1. FIG. 2 shows an image and film thickness distribution obtained by observing the sensitive film of Example 1 with a confocal microscope. The response of Example 1 to ethanol at 0% and 30% humidity is shown. 4 is a surface SEM image of the sensitive film of Comparative Example 1. FIG. Responsiveness to ethanol at humidity of 0% and 30% of Comparative Example 3 is shown. The results of microscopic ATR spectra of Example 1 and Comparative Example 5 are shown.

Hereinafter, an embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited to this, and various modifications are possible without departing from the gist thereof. is.

The sensor of this embodiment is a sensor having a sensitive film containing an organic-inorganic hybrid, wherein the organic-inorganic hybrid contains a structure represented by RSiO _3/2 , where R represents an organic functional group. and the porosity as a volume fraction of the sensitive film is 10% or less. Because of this configuration, the sensor of this embodiment can measure highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under humid conditions. , continuous measurement can be performed without deterioration of the sensitive film even after long-term use.

The sensor of this embodiment includes, but is not limited to, a sensor body of a type that detects physical parameters, for example. Physical parameters include, but are not limited to, surface stress, stress, force, surface tension, pressure, mass, elasticity, Young's modulus, Poisson's ratio, resonance frequency, frequency, volume, thickness, viscosity, density, magnetic force, magnetism quantity, magnetic field, magnetic flux, magnetic flux density, electrical resistance, electrical quantity, permittivity, power, electric field, charge, current, voltage, potential, mobility, electrostatic energy, capacitance, inductance, reactance, susceptance, admittance, impedance, conductance , plasmons, refractive index, luminosity and temperature and various other physical parameters. The sensor of this embodiment is, for example, a sensor in which a sensitive film (sometimes referred to as a "receptor layer" in this technical field) is provided directly on the sensor body. That is, the sensor of the present embodiment can detect, by the sensor main body, changes in physical parameters caused by the adsorption of analyte molecules on the sensitive film. As described above, the sensor main body that can be used in the present embodiment is particularly limited as long as it detects a change caused in the sensitive film by the sensitive film arranged on its surface adsorbing the substance to be detected. not.

When the sensor of the present embodiment is applied to, for example, a surface stress-type olfactory sensor, the sensitive film covering at least a portion of the surface of the sensor main body adsorbs a substance to be detected, causing a reaction in the sensitive film. The main body outputs a signal by detecting the stress change.

Also, another type of sensor body may be applied, for example, a QCM device. The QCM device measures minute changes in mass by using the property that when a substance is adsorbed on the electrode surface of a crystal oscillator to which an alternating electric field is applied, the resonance frequency decreases according to the mass and viscoelasticity of the adsorbate. It is a mass sensor and can be measured in-situ. When the sensor of this embodiment is applied as a QCM device, for example, by forming the sensitive film of this embodiment on the surface of the electrode, the sensor body detects the mass change caused by the adsorption of the substance to be detected by the sensitive film. Detect and output a signal. Various conductive materials can be used as the electrodes of the QCM. When the sensitive film in this embodiment is to have conductivity, the sensitive film can also be used as the electrode of the QCM.

In the present specification, the term "adsorption" is used to include a phenomenon in which the concentration of another substance (which becomes an adsorbate) increases compared to the surroundings at the interface of a certain object, and not only physical adsorption, It also includes chemisorption due to chemical bonding and biochemical action.

[Sensitive film]
The sensitive film in this embodiment contains an organic-inorganic hybrid. The organic-inorganic hybrid in this embodiment includes a structure represented by RSiO _3/2 from the viewpoint of sensitivity and stability in a humid environment, where R represents an organic functional group.

In this embodiment, the organic functional group preferably contains one or more aromatic rings. When it contains an aromatic ring, the moisture resistance tends to be further improved. The aromatic ring is not particularly limited because it can be appropriately selected in consideration of the use of the sensor, etc. Examples include aromatic hydrocarbon groups such as phenyl group, naphthyl group, p-tolyl group and biphenyl group, 4-chlorophenyl group, 4-methoxyphenyl group, 4-aminophenyl group, substituted aromatic hydrocarbon groups such as pentafluorophenyl group, 3-furyl group, 3-thienyl group, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group, etc. and metallocenes such as a ferrocenyl group and the like. The organic functional group in the present embodiment may contain one of the aromatic rings described above, or may contain two or more of them.

In the organic-inorganic hybrid, between the aromatic ring and the silicon atom, an alkyl group (having 1 to 18 carbon atoms), an ether group, a carbonyl group, a carboxyl group, an amide group, a urethane bond, a urea bond, an imide group , An imine group or other spacer structure may be interposed, but from the viewpoint of responsive sensitivity, it is preferable that the aromatic ring is directly bonded to the Si atom in the organic-inorganic hybrid without interposing such a spacer.

From the viewpoint of achieving both humidity resistance and selectivity to various gas molecules, the organic functional group in the present embodiment preferably contains a copolymer structure of an aromatic ring and a non-aromatic ring structure. In addition, from the viewpoint of responsiveness to highly polar gas and odor molecules, the organic functional group in the present embodiment includes a nitrogen atom, an oxygen atom, a sulfur atom, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a boron atom. , and phosphorus atoms. Among these, from the viewpoint of stability, the organic functional group preferably contains a functional group containing one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, and a fluorine atom.

Specific examples of the organic functional group in the present embodiment are not limited to the following, but linear or branched hydrocarbon groups that may have substituents such as halogen atoms (e.g., 3-chloropropyl group, octyl linear or branched C _1-8 alkyl groups such as groups), alicyclic hydrocarbon groups optionally having substituents such as halogen atoms (e.g., C _5-6 cycloalkyl groups such as cyclohexyl groups), Aromatic hydrocarbon groups that may have substituents such as halogen atoms (e.g., phenyl group, pentafluorophenyl group, etc.), vinyl groups, allyl groups, (meth)acrylic groups, (meth)acryloyloxyalkyl groups ( (Meth)acryloyloxy C _1-3 alkyl groups such as (meth)acryloyloxypropyl groups), epoxy groups, glycidyloxyalkyl groups (e.g. glycidyloxy C _1-3 alkyl groups such as 3-glycidyloxypropyl groups) ), (epoxycycloalkyl)alkyl group (e.g., 2-(3,4-epoxycyclohexyl)ethyl group, etc.), hydroxy group, ether group, carbonyl group, carboxyl group, ester group, urethane group, urea group, mercapto group , mercaptoalkyl groups (e.g., mercapto C _1-3 alkyl groups such as mercaptopropyl groups), sulfide groups, amino groups (e.g., primary amino groups, secondary amino groups, tertiary amino groups), aminoalkyl groups (e.g., , amino C _1-3 alkyl group such as aminopropyl group), (aminoalkylamino)alkyl group (e.g., 3-(2-aminoethylamino)propyl group), imidazolyl group, imidazolylalkyl group (e.g., 3-( 2-imidazolin-1-yl)propyl group), alkylaminoalkyl group (e.g., 3-(dimethylamino)propyl group), amide group, heterocyclic aromatic group, oxime group, imide group, imine group, halogen group, A nitrile group, a phosphonic group, a phosphoric acid group and the like can be mentioned. Among these, from the viewpoint of availability, the organic functional group is a linear or branched hydrocarbon group which may have a substituent, an alicyclic hydrocarbon group which may have a substituent, and a substituent. Aromatic hydrocarbon group, vinyl group, allyl group, (meth)acryloyloxyalkyl group, glycidyloxyalkyl group, (epoxycycloalkyl)alkyl group, mercaptoalkyl group, aminoalkyl group, (aminoalkylamino ) is preferably one or more selected from the group consisting of an alkyl group, an imidazolylalkyl group, an alkylaminoalkyl group, and a hydroxy group. These functional groups are used singly or in combination of two or more.

The organic functional group is preferably an organic functional group derived from a silane coupling agent. Silane coupling agents include hydrolyzable metal oxides such as alkoxysilanes, acetoxysilanes and chlorosilanes. Among these, hydrolyzable metal oxides are preferably alkoxysilanes from the viewpoint of handleability and versatility of functional groups, and more preferably trifunctional alkoxysilanes from the viewpoint of reactivity.
Trifunctional alkoxysilanes may be copolymerized with mono-, di-, or tetra-functional alkoxysilanes, but from the viewpoint of increasing the Young's modulus of organic-inorganic hybrids and increasing their sensitivity, copolymerization with tetra-functional alkoxysilanes is preferred. is preferred.

As the trifunctional alkoxysilane, a silane coupling agent having an alkoxy group having a methoxy group, an ethoxy group, or an isopropoxy group can be used.
Commercially available aromatic silane coupling agents include phenyltrialkoxysilane, nitrobenzeneamidetrialkoxysilane, benzyltrialkoxysilane, 4-chlorophenyltrialkoxysilane, phenylaminopropyltrialkoxysilane, 4-aminophenyltrialkoxysilane, and naphthyl. trialkoxysilane, 4-methoxytrialkoxysilane, pentafluorophenyltrialkoxysilane, ferrocenyltrialkoxysilane, biphenyltrialkoxysilane, 3-furyltrialkoxysilane, 3-thienyltrialkoxysilane, 2-pyridyltrialkoxysilane, Examples thereof include 3-pyridyltrialkoxysilane, 4-pyridyltrialkoxysilane, and the like, but are not limited to these.
Commercially available non-aromatic silane coupling agents include 3-(2-aminoethylamino)propyltrialkoxysilane, 3-mercaptopropyltrialkoxysilane, vinyltrialkoxysilane, cyclohexyltrialkoxysilane, and 3-glycidyloxypropyl. trialkoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrialkoxysilane, 3-(dimethylamino)propyltrialkoxysilane, 3-(2-imidazolin-1-yl)propyltrialkoxysilane, 3-aminopropyl trialkoxysilane, 3-(methacryloyloxy)propyltrialkoxysilane, 3-(acryloyloxy)propyltrialkoxysilane, allyltrialkoxysilane, methyltrialkoxysilane, ethyltrialkoxysilane, propyltrialkoxysilane, butylalkoxysilane, hexyltrialkoxysilane, octyltrialkoxysilane, decyltrialkoxysilane, dodecyltrialkoxysilane, octadecyltrialkoxysilane, 3-ureidopropyltrialkoxysilane, cyclohexylaminopropyltrialkoxysilane, hexafluorophenyltrialkoxysilane, 3-chloro Propyltrialkoxysilane, 3-bromopropyltrialkoxysilane, 3-piperazinopropyltrialkoxysilane, 3-morpholinopropyltrialkoxysilane, 3-allylaminopropyltrialkoxysilane, norbornyltrialkoxysilane, piperidine Examples include, but are not limited to, nopropyltrialkoxysilane.

When two or more silane coupling agents are copolymerized, the ratio of the aromatic silane coupling agent and the non-aromatic silane coupling agent is preferably 1:10 to 1:5 in terms of molar ratio. from 1:5 to 1:1 from the point of view, and preferably from 1:1 to 10:1 from the point of suppression of reduction in signal intensity under humidity.

The organic functional groups in the sensor of this embodiment can be identified by subjecting the sensitive film on the sensor body to surface elemental analysis such as SEM-EDX, XPS, and ATR.

In this embodiment, from the viewpoint of sensitivity and stability in a humid environment, the porosity as a volume fraction of the sensitive film is 10% or less. It is more preferably 5% or more from the viewpoint of further improving sensitivity, and further preferably 3% or less from the viewpoint of suppressing a decrease in sensitivity in a humid environment. The porosity can be adjusted within the above range, for example, by adjusting the ratio of the filler to the structure represented by RSiO _3/2 . Moreover, the porosity is a value measured by the method described in the Examples section of this specification or by a method understood to be equivalent thereto by those skilled in the art.

[Filler]
It is preferable that the sensitive film in the present embodiment further contains a filler. The use of a filler can improve the Young's modulus of the organic-inorganic hybrid and enhance the sensitivity. The filler in this embodiment is not particularly limited, and can be selected from various known fillers. Specific examples include, but are not limited to, polymer beads such as polystyrene, polymethyl methacrylate, and polyphenylene oxide, spherical particles such as acrylic latex, metal nitrides such as silicon nitride, silica, zirconia, titania, zinc oxide, and aluminum oxide. , metal oxides such as tin oxide, barium titanate, strontium titanate, composite metal compounds such as ITO, and inorganic metal fillers such as gold, silver, copper, palladium, platinum, iron, aluminum, etc. be able to.

From the viewpoint of dispersibility and coatability, the filler in the present embodiment is preferably an inorganic filler. From the same viewpoint as above, in the present embodiment, metal compounds such as silica, zirconia, titania, and alumina, and inorganic metal fillers such as gold, silver, copper, palladium, platinum, iron, and aluminum are preferable, and moisture under humidity is preferred. Metal oxides such as silica and zirconia are more preferable because they are less affected by signal attenuation, and silica is more preferable from the viewpoint of economy. The inventors have found that, especially when silica is used, the attenuation of the response of common hydrophilic gases such as ethanol, acetaldehyde, etc. is significantly improved even in humid conditions. The reason for this is considered as follows, but it is not intended to be limited to the following. That is, since the hydroxyl group present in a state bonded to the skeleton of silica and the silicon atom is relatively hydrophobic compared to the hydroxyl group bonded to the titania skeleton or titanium atom of Patent Document 1, the hydrophobic interaction causes It is presumed that the adsorption inhibition of

The shape of the filler is not particularly limited, but is preferably spherical, rod-like, plate-like, fibrous, or a combination of two or more of these, more preferably spherical or chain-like. The term "spherical" as used herein means not only a perfect sphere, but also a substantially spherical shape including spheroids, ovoids, and the like.

The size of the spherical filler is not particularly limited, but from the viewpoint of maintaining ink dispersibility, preventing nozzle clogging, and improving ink-jet coating properties, the average primary particle size should be 100 μm or less. It is preferably 500 nm or less from the viewpoint of improving sensitivity, and further preferably 200 nm or less from the viewpoint of further reducing voids. Here, the average primary particle diameter means a number average value. The average primary particle size of 50 particles measured by the method using a scanning electron microscope as described in the Examples section of this specification, or by a method understood to be equivalent to this It is a numerical average value.

The chain-like filler preferably has a continuous chain-like structure. A structure (also referred to as a "pearl necklace-like" structure), or a structure in which a number of thread-like structures are not observed as individual continuous spheres but are entwined (also referred to as a "network-like" structure). is mentioned as a preferable example.

The filler that constitutes the continuous chain structure is generally assumed to be spherical, and it is not easy to define it by the primary particle size, but the chain width can be observed by transmission or scanning electron microscope observation. The chain width is 1 nm to 200 nm, preferably 1 nm to 100 nm from the viewpoint of increasing the surface area covered, and more preferably 1 nm to 85 nm from the viewpoint of gas responsive sensitivity. The average primary particle size of 50 particles measured by the method using a scanning electron microscope as described in the Examples section of this specification, or by a method understood to be equivalent to this Number average, defined as chain width.

Such a metal oxide as a filler can be produced by a sol-gel method using a metal oxide precursor having a tetrafunctional hydrolyzable group such as alkoxy or chloro, or a commercially available product can be used. can also Metal oxide precursors having a tetrafunctional hydrolyzable group include tetraalkoxysilane, tetrachlorosilane, tetraalkoxytitanium, tetraacetoxyzirconium and the like. These tetrafunctional hydrolyzable metal inorganic oxides may be copolymerized with trifunctional hydrolyzable metal oxides, and the shape can be obtained by adjusting the concentration, temperature, pH, water content, etc. of the reaction system. can be controlled. It is conceivable that a structure represented by RSiO _3/2 may be obtained on the filler side, for example, when the filler is produced by emulsion polymerization. shall be treated as an organic-inorganic hybrid in form.

Commercially available fillers that can be used include the LEVASIL series (manufactured by HC Starck Co., Ltd.), the Quartron PL series (manufactured by Fuso Chemical Co., Ltd.), the OSCAL series (manufactured by Catalysts and Chemicals Industry Co., Ltd.), and the like; Examples of powdery silica particles include Aerosil 130, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil OX50 (manufactured by Nippon Aerosil Co., Ltd.), Sildex H31, Sildex H32, Sildex H51, Sildex H52, Sildex H121, Same H122 (manufactured by Asahi Glass Co., Ltd.), E220A, E220 (manufactured by Nippon Silica Industry Co., Ltd.), SYLYSIA470 (manufactured by Fuji Silysia Co., Ltd.), SG flake (manufactured by Nippon Sheet Glass Co., Ltd.), etc., IPA- ST, IPA-ST-L, IPA-ST-ZL, ST-XS, ST-S, ST-30, ST-50T, ST-30L, ST-YL, ST-ZL, MP-1040, MP-2040, MP-4540M, ST-OXS, ST-OS, ST-O, ST-O-40, ST-OL, ST-OYL, ST-NXS, ST-NS, ST-N, ST-N-40, ST- CXS, ST-C, ST-CM, ST-AK, ST-AK-L, ST-AK-YL, OZ-S30K, SZ-S30K-AC, OZ-S30M, CELNAX CX-S505M, IPA-ST- UP, MEK-ST-UP, ST-UP, ST-PS-S, ST-PS-M, ST-OUP, ST-PS-SO, ST-PS-MO, ST-AK-PS-S, etc. (Nissan Chemical Co., Ltd.), SRD-K, SRD-M, SXR-CM, SZR-K, SZR-M (manufactured by Sakai Chemical Co., Ltd.). Examples of powdery fillers include Aerosil 130, Aerosil 300, Aerosil 380, Aerosil TT600, Aerosil OX50 (manufactured by Nippon Aerosil Co., Ltd.), Sildex H31, Sildex H32, Sildex H51, Sildex H52, and Sildex H121. H122 (manufactured by Asahi Glass Co., Ltd.), E220A, E220 (manufactured by Nippon Silica Industry Co., Ltd.), SYLYSIA470 (manufactured by Fuji Silysia Co., Ltd.), SG flake (manufactured by Nippon Sheet Glass Co., Ltd.), etc. can be done.

[Method for producing organic-inorganic hybrid]
Although the method for producing the organic-inorganic hybrid is not particularly limited, it is mainly produced using a sol-gel method. Specifically, a hydrolyzable silane compound (including a silane coupling agent) is treated by a sol-gel method under acidic and basic conditions in the presence of water to produce a condensate of the silane coupling agent, namely RSiO ₃ . Organic-inorganic hybrids containing structures represented by _/2 can be obtained.

From the viewpoint of being able to control the reaction rate of hydrolysis and condensation, it is more preferable to hydrolyze and condense the silane coupling agent and modify the surface in the presence of a catalyst.
Types of catalysts include acid catalysts and base catalysts. Acid catalysts include, for example, inorganic acids and organic acids. Examples of inorganic acids include, but are not limited to, hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, and boric acid. Examples of organic acids include, but are not limited to, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic acid, methylmalonic acid, and benzoic acid. acid, p-aminobenzoic acid, p-toluenesulfonic acid, benzenesulfonic acid, trifluoroacetic acid, formic acid, malonic acid, sulfonic acid, phthalic acid, fumaric acid, citric acid, tartaric acid, citraconic acid, malic acid, glutaric acid, etc. is mentioned. Base catalysts include, for example, inorganic bases and organic bases. Examples of inorganic bases include, but are not limited to, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; alkali or alkaline earth metal carbonates such as lithium, potassium carbonate and sodium carbonate; metal hydrogencarbonates such as potassium hydrogencarbonate and sodium hydrogencarbonate; and the like. Examples of organic bases include, but are not limited to, trialkylamines such as triethylamine and ethyldiisopropylamine; N,N-dialkylaniline derivatives having 1 to 4 carbon atoms such as N,N-dimethylaniline and N,N-diethylaniline; pyridine derivatives optionally having an alkyl substituent having 1 to 4 carbon atoms, such as pyridine and 2,6-lutidine; and the like. These catalysts can be used singly or in combination of two or more.

It is preferable in terms of reaction efficiency to add an amount of catalyst that brings the pH of the reaction system to a range of 0.01 to 6.0, or pH 8 to 14. In order to further increase efficiency, basic conditions of pH 8 to 14 are used. It is more preferable to carry out the sol-gel reaction under

Hydrolysis and condensation to produce organic-inorganic hybrids can also be carried out in organic solvents. Examples of organic solvents that can be used in the condensation reaction include alcohols, esters, ketones, ethers, aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, amide compounds and the like.

Examples of the alcohol include, but are not limited to, monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol; ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, hexanetriol Polyhydric alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene monoethers of polyhydric alcohols such as glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether; and the like.

Examples of the ester include, but are not limited to, methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone, and the like. Examples of ketones include, but are not limited to, acetone, methyl ethyl ketone, methyl isoamyl ketone, and the like.

Examples of the ether include, in addition to the above monoethers of polyhydric alcohols, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, and propylene. Polyhydric alcohol ethers obtained by alkyl-etherifying all hydroxyl groups of polyhydric alcohols such as glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether and diethylene glycol diethyl ether; tetrahydrofuran; 1,4-dioxane; anisole and the like.

Examples of the aliphatic hydrocarbon compound include, but are not limited to, hexane, heptane, octane, nonane, and decane.

Examples of the aromatic hydrocarbon compound include, but are not limited to, benzene, toluene, and xylene.

Examples of the amide compound include, but are not limited to, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like.

Among the above solvents, alcohols such as methanol, ethanol, isopropanol, butanol, etc.; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.; ethers such as ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. ; and amide compounds such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone are preferred because they are easily mixed with water. These solvents may be used alone or in combination of multiple solvents.

When the organic-inorganic hybrid is blended with a filler, the organic-inorganic hybrid may be produced in the presence of the filler, or the organic-inorganic hybrid may be blended with the filler. A condensate of a silane coupling agent may be dissolved in a commercially available dispersion filler, a filler and a silane coupling agent may be dispersed using a ball mill, a jet mill, or the like, or the alkoxysilane and the filler may undergo a condensation reaction at the same time. However, from the viewpoint of enhancing the solvent dispersibility of the filler and improving the ink jet applicability, the production method of condensing the alkoxysilane and the filler at the same time is more preferable. When the colloidal filler is treated by the sol-gel method in the presence of a silane coupling agent, the condensate of the silane coupling agent modifies the surface of the filler while filling the gaps. The pore volume can be adjusted by adjusting the amount arbitrarily. When hydroxyl groups are present on the surface of the filler, the surface hydroxyl groups and the hydroxyl groups generated by hydrolysis of the alkoxysilane interact and form ether bonds through a condensation reaction, so the compatibility between the filler and the condensate can be enhanced. , a more stable sensitive film can be obtained.

The surface modification of the filler with organic functional groups is carried out by surface modification while the filler is dispersed in a dispersion medium. Specifically, for example, an organic-inorganic hybrid is produced by adding the silane coupling agent to a uniform dispersion of metal oxides containing alcohol and water in the presence of a catalyst.

The organic-inorganic hybrid may be recovered by centrifuging and filtering the precipitate or gelled product, or isolated by removing the volatile solvent with an evaporator or the like.

Introduction of an organic functional group can be confirmed by FT-IR or elemental analysis. Moreover, it can be confirmed by thermogravimetric loss measurement. In order to remove the influence of adsorbed water, the thermal weight loss rate of the organic content of the inorganic filler (i) and the organic functional group (ii) combined from 150 ° C. to 1000 ° C. is 3% to 75% from the viewpoint of sensitivity. , more preferably 5% to 65% from the viewpoint of humidity resistance, and even more preferably 5% to 60% from the viewpoint of thermal stability. That is, the amount of the organic functional group in the organic-inorganic hybrid in the present embodiment is not particularly limited, but from the viewpoint of the balance between the responsiveness to the analyte and the stability of the sensitive film, it is preferably 75% by weight or less. Preferably, it is 65% by weight or less.

The film thickness of the sensitive film in this embodiment may be a shape in which the organic-inorganic hybrid has a uniform film thickness distribution, or may have a coffee ring shape in which the film thickness is distributed so as to be thicker at the ends. In the case of a coffee ring shape, the film thickness of the thinnest portion at the central portion of the sensitive film and the thickest portion at the end portions are preferably 10 nm or more and 50 μm or less. The film thickness is preferably 10 nm or more and 30 μm or less from the viewpoint of shortening the time required for drying during production and increasing productivity, and more preferably 10 nm or more and 20 μm or less from the viewpoint of increasing sensitivity. Further, the maximum thickness of the sensitive film in this embodiment is preferably 30 μm or less. The above film thickness and maximum thickness can be measured by the methods described in Examples below.

In order to use the surface stress sensor (MSS) coated with the sensitive film in this embodiment as an olfactory sensor, the organic functional groups and gas molecules interact in the gas phase and diffuse into the sensitive film to generate stress. and thereby detect the gas.

[Surface stress sensor (MSS)]
The sensor of this embodiment can be used as a surface stress sensor (MSS). The MSS is preferably a piezo element type MSS fixed at four points.

[Sensor manufacturing method]
The method of manufacturing the sensor of this embodiment is not particularly limited, but various methods for forming a sensitive film on the sensor body can be used. The sensitive film in the present embodiment is manufactured by, for example, dispersing an organic-inorganic hybrid in an organic solvent to prepare a coating liquid, and coating the coating liquid on the sensor main body. An inkjet device can be suitably used when applying the coating liquid onto the chip of the sensor. According to the inkjet device, droplets of a coating liquid are ejected, the droplets are coated on the sensor, and a sensitive film is formed. FIG. 1 shows an example in which a sensitive film is formed on a chip. The sensor 1 is configured to have a chip 3 corresponding to the sensor body and a sensitive film 2 formed on the surface thereof. In the example shown in FIG. 1, such a configuration is provided at four locations. .

The method for coating the organic-inorganic hybrid on the surface of the sensor body (e.g., MSS body) is not particularly limited, but for example, dip coating, spray coating, spin coating, inkjet spotting, casting, coating using a doctor blade, etc. method.

Inkjet or microjet methods are preferable for coating on a 300 μmφ MSS membrane, and microjet coating is more preferable from the viewpoint of productivity.

The sensitive film can be produced, for example, by dispersing an organic-inorganic hybrid in an organic solvent and coating the dispersion on the MSS chip. The organic-inorganic hybrid is dispersed in an organic solvent at a concentration of 0.1 g/L to 50 g/L to form a coating liquid. From the viewpoint of productivity, the concentration is preferably 0.5 to 50 g/L, and from the viewpoint of suppressing nozzle clogging, it is more preferably 0.5 to 15 g/L.

The organic solvent for dispersing the organic-inorganic hybrid may be any solvent that can be dispersed, and preferably has a boiling point of 80°C to 250°C. A temperature of 250° C. is preferable, and a temperature of 100° C. to 200° C. is more preferable in order to shorten the drying time and improve productivity.

Examples of organic solvents include, but are not limited to, alcohol solvents, ester solvents, ketone solvents, ether solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, amide solvents, and the like.

Alcohol solvents include, but are not limited to, monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, and hexanetriol; Alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol mono monoethers of polyhydric alcohols such as ethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether; and the like.
Examples of ester solvents include methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone and the like.

Examples of ketone solvents include, but are not limited to, acetone, methyl ethyl ketone, methyl isoamyl ketone, and the like.

Examples of ether solvents include, but are not limited to, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, diethylene glycol dimethyl ether, Polyhydric alcohol ethers obtained by alkyl-etherifying all hydroxyl groups of polyhydric alcohols such as diethylene glycol methyl ethyl ether and diethylene glycol diethyl ether; tetrahydrofuran; 1,4-dioxane; anisole;

Examples of aliphatic hydrocarbon solvents include, but are not limited to, hexane, heptane, octane, nonane, decane, and the like.

Examples of aromatic hydrocarbon solvents include, but are not limited to, benzene, toluene, xylene, and the like.

Examples of amide solvents include, but are not limited to, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and the like.

These organic solvents may be used singly or in combination of two or more.

Among these organic solvents, N,N-dimethylformamide and propylene glycol monomethyl ether are preferred because of their excellent safety and solubility.

The sensitive film in this embodiment may contain additives such as arbitrary particles, ionic compounds, resins, and low-molecular-weight compounds in addition to organic-inorganic hybrids. For example, the additive can be blended in a coating solution and applied to the surface of the sensor body to obtain a sensor having a sensitive film containing the additive.

EXAMPLES The present embodiment will be specifically described below with reference to examples and comparative examples, but the present embodiment is not limited to these.

Various physical properties of MSS of each example and comparative example were evaluated according to the following (1) to (8).

(1) Measurement of Porosity of Organic-Inorganic Hybrid Sensitive Film A sample having a cross section formed by dicing was fixed on a processing table, processed by FIB Milling described below, and observed with an SEM. The SEM observation conditions were as follows.
(Processing conditions FIB Milling)
Equipment Helios 650
Rough processing Executed after forming a protective film with W Acceleration voltage 30 kV
Change current value in order of 9.4nA, 2.4nA, 0.7nA (finishing)
Accelerating voltage 30 kV
Current value 0.24nA
(SEM observation conditions)
Apparatus Helios 650 (manufactured by ThermoFisher SCIENTIFIC)
Acceleration voltage 2 kV, 0.1 or 0.2 nA
Observation image Backscattered electron image (composition image)
Incline 52°

The uneven fine structure layer was cut out from the image obtained by cross-sectional SEM observation, and the voids present in the organic-inorganic hybrid were extracted. For the extraction, binarization processing was performed using image analysis software, taking advantage of the fact that in the acquired image, the gaps have a bright contrast due to the edge effect, and that the gaps themselves have a dark contrast. At that time, a binarization process was performed in which the concave-convex microstructure layer was white, and the voids, the substrate, and the background were black. Parts that could not be followed by the binarization process were supplemented by manual discrimination. In the extracted image of the voids obtained, the ratio of the area of the portion corresponding to the void to the area of the uneven fine structure layer and the void was calculated as the void ratio in the uneven fine structure layer. The above operation was performed for 3 fields of view, and the numerical average value was defined as the porosity.

(2) Identification of Organic Functional Group Species in Organic-Inorganic Hybrid Organic functional groups in the organic-inorganic hybrid were identified by measuring the sensitive film on the main body of the sensor by a microscopic ATR method based on the following conditions.
(Measurement condition)
Apparatus used; Cary620 (manufactured by Agilent)
Measurement method; microscopic ATR method (crystal: Ge) using a slide-on type ATR attachment Detector; MCT (HgCeTe) infrared detection element Aperture size; about 100um
IR incident angle to ATR crystal 30°
Resolution; 4 cm ^-1
Accumulation times; 64 scans

(3) Thermal weight loss rate (quantification of the amount of organic functional groups)
A powder sample of the sensitive film scraped from the sensor was dried in air at 100° C., then returned to room temperature and weighed accurately. Thereafter, the organic component was removed by heating to 1000° C. at a rate of 10° C./min in the atmosphere using TGA, and the thermal weight loss rate was obtained. Since only the organic functional group is not decomposed by heating and the SiO _3/2 portion remains as silica, the thermal weight loss rate was defined as the amount of organic functional group (% by mass).

(4) Maximum thickness of the sensitive film By observing the uncoated part of the sensitive film and the maximum thickness part of the sensitive film in the sensor using a confocal laser microscope (VK09700 Violet Laser (manufactured by Keyence)), the thickness of the sensitive film was measured. That is, the cross-sectional profile between two points on the diameter of the sensitive film formed in a substantially circular shape was obtained, the uncoated portion and the maximum film thickness portion were specified from the cross-sectional profile, and the difference between them was taken as the maximum thickness.
(Observation conditions)
Objective lens: Standard lens, 20.0x Measurement area: Plane Measurement mode: Surface shape RPD: Accuracy priority Measurement quality: High definition Measurement pitch: 0.5 μm
Z measurement distance: 37.92 μm
Wide dynamic range: OFF
Brightness 1:648
Neutral filter: 100%
Optical zoom: 1x Average count: 1 Filter: OFF
White balance mode: One push White balance R: 131
White balance B: 138
Received light amount correction mode: γ correction γ correction value: 0.45
γ offset: 0
Black and white inversion: OFF
Head type: VK-9700
Light intensity eccentricity correction: ON
Field curvature correction: ON
XY calibration: 688 nm/pixel
Z calibration: 1 nm/digit
Vividness: 5
Contrast: 5
Brightness: 0

(5) Influence of Humidity Resistance 25° C., 100 ppm of ethanol for 10 minutes/purging with only nitrogen was repeated three times for 10 minutes each, and the third signal was adopted. 100 × ("Intensity of the third signal measured under dry" - "Intensity of the third signal measured under 30 RT%") / ("Intensity of the third signal measured under dry" is the attenuation rate (%), and when the value is 20% or less, it is ◎, when it is 21% to 40% or less, it is ○, when it is 41% or more and less than 50%, it is △, when it is 51% or more, it is x. .

(6) Physical and chemical stability Water-saturated steam, ethanol, and toluene (flow rate 30 sccm) at 25°C for 10 minutes/purge purge (under dry nitrogen) for 10 minutes were sequentially measured three times each, and the film shape was observed with an optical microscope. When deformation was observed up to ethanol, △ was observed when deformation was observed in toluene, and ◯ was observed when no deformation was observed after any of them.

(7) Heat resistance (reflow resistance)
After reflowing at 250° C. for 30 seconds, peeling, deformation, cracking, etc. were observed in the sensitive film, and those not observed were evaluated as ◯.

(8) Filler particle size (diameter)
The number average value of 50 filler particles was obtained using the scanning electron microscope described in (1) above. In the case of spherical particles, the maximum diameter was defined as the particle diameter, and in the case of chain-shaped particles, the chain width was defined as the particle diameter, and the number average value for 50 particles was calculated.

<Example 1>
In a separable flask, 27.1 g of phenyltrimethoxysilane was added to 50 g of chain colloidal silica 2-propanol dispersion IPA-ST-UP (Nissan Kagaku), 90 g of water, 10 g of 28% aqueous ammonia, and 300 g of 2-propanol. The reaction was carried out at 80°C for 4 hours. After air-cooling the reaction solution, the precipitate was isolated by centrifuging at 6000 rpm for 10 minutes. After thoroughly washing the sample with ethanol, it was dissolved in N,N dimethylformamide to a concentration of 10 g/mL to obtain a coating solution. A portion of the sample was dried at 80° C. under vacuum and the thermal weight loss rate was measured. A surface stress sensor with a sensitive film was obtained by applying 30 droplets of the coating liquid in an amount of 300 pL per droplet onto the MSS surface placed on a hot plate at 80° C. using an inkjet device. Its appearance was the same as that shown in FIG.

FIG. 2 shows an image of the central portion of the sensitive film obtained by observing the surface of the surface stress sensor according to Example 1 with an SEM. As can be seen from FIG. 2, in the central portion of the sensitive film in the surface stress sensor according to Example 1, the sensitive film was uniformly formed on the sensor main body.
Next, FIG. 3 shows the result of cross-sectional SEM observation of the surface stress sensor according to Example 1. As shown in FIG. Based on such a cross-sectional SEM image, the porosity was calculated as described in (1) above. Results are shown in Table 1.
Moreover, as a result of measuring the maximum thickness of the surface stress sensor according to Example 1 based on the method (4) above, the image shown in the upper part of FIG. 4 was obtained. From the image at the top of FIG. 4, it can be seen that a coffee-ring-shaped sensitive film is formed on the main body of the sensor measuring 700 μm long×500 μm wide. Furthermore, as a result of analyzing the film thickness, the film thickness distribution shown in the lower part of FIG. 4 was obtained. The image at the bottom of FIG. 4 shows a cross-sectional profile between two points in the XX' cross section at the top of FIG. A maximum thickness was obtained. Results are shown in Table 1.
Furthermore, FIG. 5 shows the result of examining the effect of humidity resistance based on the method (5) above. A maximum amplitude of 550 μV was obtained at a humidity of 0% (dry) and a maximum amplitude of 360 μV was obtained at a humidity of 30%. Since the attenuation rate calculated by the method described above was 40%, ◯ was given.
The following examples and comparative examples were also evaluated in the same manner as the method described above.

<Example 2>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 13.5 g.

<Example 3>
Example 1 was followed except that 50 g of IPA-ST-UP (Nissan Kagaku) was changed to 25 g of IPA-ST (12 nm spherical silica).

<Example 4>
Example 1 was followed except that 50 g of IPA-ST-UP (Nissan Kagaku) was changed to 25 g of IPA-ST-L (45 nm spherical silica).

<Example 5>
Example 1 was followed except that 50 g of IPA-ST-UP (Nissan Kagaku) was changed to 20 g of MP-4540M (450 nm spherical silica).

<Example 6>
Example 1 was followed except that 50 g of IPA-ST-UP (product of Nissan Chemical Industries) was changed to 20 g of ZR-40BL (90 nm zirconia).

<Example 7>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 37.6 g of 4-chlorophenyltriethoxysilane.

<Example 8>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 30.4 g of 4-methoxyphenyltrimethoxysilane.

<Example 9>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 31.5 g of 3-furyltriethoxysilane.

<Example 10>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 33.9 g of 3-thienyltriethoxysilane.

<Example 11>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 23.3 g of 4-aminophenyltrimethoxysilane.

<Example 12>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was replaced with 29 g of p-tolyltrimethoxysilane.

<Example 13>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.2 g of naphthalenetrimethoxysilane.

<Example 14>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+37.5 g of 3-(2-imizazolinepropyl)triethoxysilane.

<Example 15>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+36.1 g of 3-(2-aminopropylethylamino)propyltriethoxysilane.

<Example 16>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+35.7 g of norbornyltriethoxysilane.

<Example 17>
Example 1 was repeated except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+7.08 g of 3-N,N-dimethylaminopropyltrimethoxysilane.

<Example 18>
Example 1 was repeated except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+9.77 g of 3-mercaptopropyltriethoxysilane.

<Example 19>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 24.4 g of phenyltrimethoxysilane+3.93 g of pentafluorophenyltrimethoxysilane.

<Example 20>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+11.9 g of 3-methacryloxypropyltriethoxysilane.

<Example 21>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+8.75 g of 2-(3,4-epoxycyclohexyltrimethoxysilane.

<Example 22>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane and 8.74 g of 4-aminophenyltrimethoxysilane.

<Example 23>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+21.6 g of 3-ureidopropyltriethoxysilane.

<Example 24>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+10.4 g of 3-phenylaminopropyltrimethoxysilane.

<Example 25>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.1 g of phenyltrimethoxysilane+25.3 g of 3-[bis[(diphenylphosphino)methyl]amino]propyltrimethoxysilane.

<Example 26>
10 g of phenyltrimethoxysilane, 10 g of water, 30 g of ethanol and 28% aqueous ammonia were mixed and reacted at 80° C. for 2 hours. The precipitate was isolated by centrifugation at 6000 rpm for 10 minutes. After thoroughly washing the sample with ethanol, it was dissolved in N,N-dimethylformamide to a concentration of 1 g/mL to obtain a coating solution. The coating solution was applied onto the MSS surface placed on a hot plate at 80° C. with 300 drops at a volume of 300 pL per drop using a microjet.

<Example 27>
30 g of ethanol, 4.7 g of tetraethoxysilane, 4.3 g of phenyltriethoxysilane, and 1.8 g of 28% aqueous ammonia were mixed in a 500 mL separable flask, stirred, and allowed to stand at room temperature until gelation. The resulting gel was washed with ethanol to remove ammonia, and then dissolved in DMF to a concentration of 10 mg/mL to obtain a coating solution. The coating solution was applied onto the MSS surface placed on a hot plate at 80° C. with 30 drops at a volume of 300 pL per drop using a microjet.

<Example 28>
In a 500 mL separable flask, 37 g of ethanol, 2.6 g of tetraethoxysilane, 9.0 g of phenyltriethoxysilane, and 2.26 g of 28% aqueous ammonia were mixed, stirred, and allowed to stand at room temperature until gelation. The resulting gel was washed with ethanol to remove ammonia, and then dissolved in DMF to a concentration of 10 mg/mL to obtain a coating solution. The coating solution was applied onto the MSS surface placed on a hot plate at 80° C. with 30 drops at a volume of 300 pL per drop using a microjet.

<Example 29>
Example 9 was followed except that 10.1 g of 3-furyltriethoxysilane was used.

<Example 30>
Example 9 was followed except that 17.3 g of 3-furyltriethoxysilane was used.

<Example 31>
A surface stress sensor with a sensitive film was obtained by applying 150 droplets of the coating liquid of Example 1 in an amount of 700 pL per droplet to the MSS surface placed on a hot plate at 80°C using an inkjet device. rice field.

<Comparative Example 1>
Silica-titania particles (granular) were synthesized according to the method described in WO2016/121155. It was synthesized by cohydrolysis and condensation polymerization reaction of aminopropyltrimethoxysilane and titanium tetraisopropoxide (TTIP) in an ammonia basic isopropanol (IPA) aqueous solution in which octadecylamine (ODA) was dissolved. The above synthesis reaction was carried out using a Teflon (registered trademark) microreactor having a micrometer-sized Y-shaped channel. The four precursor solutions are solution 1: aminopropyltrimethoxysilane/IPA, solution 2: H ₂ O/IPA/ammonia, solution 3: TTIP/IPA, and solution 4: H ₂ O/IPA. The volume was adjusted up to 4 and prepared. The precursor solution was simultaneously fed at a constant speed by a syringe pump. Solutions 1 and 2, and solutions 3 and 4 were mixed in parallel microreactors, respectively, and the discharged liquids from both reactors were further mixed in another microreactor to form one reaction liquid. The reaction liquid was discharged into a separately prepared precursor solution 5: ODA/H2O/IPA, and stirred at a constant speed until the discharge was completed. After that, it was allowed to stand at room temperature to obtain a nanoparticle (NH ₂ —STNP) dispersion. Since such nanoparticles were confirmed to have a structure represented by RSiO _3/2 , they were treated as organic-inorganic hybrids. After air-cooling the reaction solution, the precipitate was isolated by centrifuging at 6000 rpm for 10 minutes. After thoroughly washing the sample with ethanol, it was dissolved in N,N-dimethylformamide to a concentration of 1 g/mL to obtain a coating solution. A surface stress sensor with a sensitive film was obtained by applying 300 droplets of the coating liquid in an amount of 300 pL per droplet onto the MSS surface placed on a hot plate at 80° C. using a microjet.

FIG. 6 shows the result of observing the surface of the sensitive film in the surface stress sensor according to Comparative Example 1 in the same manner as in Example 1. FIG. Compared with Example 1, in Comparative Example 1, many voids were observed.
Also, as in Example 1, FIG. 7 shows the result of confirming the response signal to 100 ppm ethanol at 0% and 30% humidity. Comparative Example 1 showed significant signal attenuation with 30% humidity.

<Comparative Example 2>
Comparative Example 1 was followed except that a nanoparticle (C ₁₈ -STNP) dispersion obtained by using octadecyltriethoxysilane instead of aminopropyltrimethoxysilane was used. Since the structure represented by RSiO _3/2 was confirmed in the above nanoparticles, they were treated as an organic-inorganic hybrid.

<Comparative Example 3>
Comparative Example 1 was followed except that a nanoparticle (phenyl-STNP) dispersion obtained by using phenyltrimethoxysilane instead of aminopropyltrimethoxysilane was used. Since the structure represented by RSiO _3/2 was confirmed in the above nanoparticles, they were treated as an organic-inorganic hybrid.

<Comparative Example 4>
Poly(methyl methacrylate) (Aldrich, average Mw ~15,000 by GPC, powder) was diluted with N,N-dimethylformamide to 1 g/mL to prepare a coating solution. 300 droplets of the coating solution were applied onto the MSS surface placed on a hot plate at 80° C. using a microjet at a volume of 300 pL per droplet. No signal was observed at 100 ppm of ethylene, and 500 ppm of ethylene, ethanol, acetaldehyde, and toluene were measured at 25°C three times each for 10 minutes/purge for 10 minutes. did.

<Comparative Example 5>
A chain colloidal silica 2-propanol dispersion IPA-ST-UP (Nissan Kagaku Co., Ltd.) was diluted with DMF to 10 mg/mL, and 350 drops were applied at an amount of 300 pL per drop using an inkjet device. A surface stress sensor with a sensitive film was obtained by coating the MSS surface placed on a hot plate at 80°C.

<Comparative Example 6>
A chain colloidal silica 2-propanol dispersion IPA-ST-UP (Nissan Kagaku Co., Ltd.) was diluted with DMF to 10 mg/mL, and an inkjet device was used to apply 30 drops in an amount of 300 pL per drop. A surface stress sensor with a sensitive film was obtained by coating the MSS surface placed on a hot plate at 80°C.

FIG. 8 shows the results of identifying the organic functional groups in the sensitive film on the sensor body in Example 1 and Comparative Example 5 by the method (2) above. A signal originating from the introduced phenyl group was detected. Also, in Example 1, a structure represented by RSiO _3/2 was observed, whereas in Comparative Example 5, such a structure was not observed. Organic functional group species were similarly identified for other examples and comparative examples.

The results of the above measurements (1) to (8) for each example/comparative example are shown in Tables 1 to 3 below.

INDUSTRIAL APPLICABILITY The sensor of the present invention exhibits the effect of exhibiting a response with high sensitivity to hydrophilic gases such as ethanol and acetaldehyde even in the presence of humidity, so it can be suitably used in the field of food transportation management.

1 sensor 2 sensitive film 3 chip (sensor body)

Claims (16)

A sensor having a sensitive membrane comprising an organic-inorganic hybrid,
The organic-inorganic hybrid comprises a structure represented by _RSiO3/2 , wherein R represents an organic functional group;
The sensor, wherein the porosity as a volume fraction of the sensitive film is 10% or less. 2. The sensor of claim 1, wherein the porosity is 5% or less. 3. The sensor of claim 1 or 2, wherein the porosity is 3% or less. The sensor according to any one of claims 1 to 3, wherein said sensitive film further comprises a filler. 5. The sensor of Claim 4, wherein the filler is an inorganic filler. 6. A sensor according to claim 4 or 5, wherein said filler is a metal oxide. A sensor according to any one of claims 4 to 6, wherein said filler is silica. The sensor according to any one of claims 4 to 7, wherein the shape of said filler is spherical or chain-like. The sensor of any one of claims 1-8, wherein the organic functional group comprises an aromatic ring. The sensor of any one of claims 1-9, wherein the aromatic ring is directly attached to a Si atom in the organic-inorganic hybrid. The sensor according to any one of claims 1 to 10, wherein the organic functional group comprises a copolymer structure of an aromatic ring and a non-aromatic ring structure. The sensor according to any one of claims 1 to 11, wherein the organic functional group includes at least one selected from the group consisting of halogen atoms, nitrogen atoms, oxygen atoms, phosphorus atoms, sulfur atoms and boron atoms. . The sensor according to any one of claims 1 to 12, wherein the organic functional group content in the organic-inorganic hybrid is 75% by weight or less. The sensor according to any one of claims 1 to 13, wherein the amount of organic functional groups in the organic-inorganic hybrid is 65% by weight. The sensor according to any one of claims 1 to 14, wherein the sensitive film has a maximum thickness of 30 µm or less. The sensor according to any one of claims 1 to 15, which is a surface stress sensor.

Images