JP2020016461A - sensor - Google Patents

Abstract

To provide a sensor capable of measuring gas such as ethylene of a growth hormone of a plant with high sensitivity even under humid conditions and further capable of continuously measuring without deterioration of a sensitive film after reflow processing and even after long-time use.SOLUTION: The sensor is a surface stress sensor having a sensitive film containing an organic-inorganic hybrid. The organic-inorganic hybrid includes a metal oxide (i) having a continuous chain structure mutually bonded by a chemical bond while an organic functional group (ii) is introduced on the surface or inside of the metal oxide.SELECTED DRAWING: None

Description

  The present invention relates to sensors.

  In general, a sensor has a detection unit (receptor) that enables highly sensitive and highly selective detection of an analyte of interest. A wide variety of substances such as self-assembled membranes, monomolecular membranes, DNA / RNA, proteins, antigens / antibodies, and polymers have been used as receptors. In the field of olfaction / gas sensors, new applications are expected in the future due to the development of AI and IoT in recent years. BACKGROUND ART In recent years, the disposal of fruits and vegetables due to overmaturation of food in the process of transporting food has been recognized as a major problem worldwide. During the process of maturation of fruits and vegetables, inherent gases such as ethylene, ethanol, and acetaldehyde are released, and in particular, monitoring ethylene in addition to other gases is extremely important for managing foods using sensors.

  In Patent Document 1, a porous material or a granular material is coated on a sensor body of a type for detecting a physical parameter, and the analyte molecule is changed by a change in the physical parameter due to the adsorption of the analyte molecule by the porous material or the granular material. A sensor for detecting is described.

  In Patent Document 2, a receptor layer of a complex including a base material and a particulate material, and a change in physical parameters that occur when analyte molecules are adsorbed to the receptor layer, having the receptor layer on the surface, A sensor having a sensor body for detection is described.

  Patent Document 3 discloses a gas sensor including, as constituents, a substrate and a metal oxide semiconductor film formed on the substrate, the surface of which is an organic layer having a functional group capable of hydrogen bonding with the surface of the metal oxide semiconductor. A gas sensor having a function of selectively responding to a polar gas, characterized by being modified with a gas sensor, is described.

  Patent Document 4 discloses a nitric oxide detection element including a base and a detection film formed on the surface of the base, wherein the detection film is formed of nitric oxide detection particles and a polymer adhesive, A nitric oxide detecting element, wherein the nitric oxide detecting particles have a porphyrin skeleton and are formed by adsorbing a dye having divalent cobalt as a central metal on the surface of the inorganic particles, is described. ing.

WO2016 / 121155 WO2016 / 136905 JP-A-2004-271366 WO2012 / 017605

  In Patent Documents 1 and 2, while realizing high sensitivity, selectivity, and stability, the electric signal is greatly attenuated except in a dry atmosphere, and the environment that can be used as an olfactory sensor is greatly limited, and the detection sensitivity of ethylene gas is also high. Is very small.

  Patent Document 3 discloses a conventional metal oxide semiconductor type gas sensor, which requires a large amount of power due to the necessity of heating a receptor portion, and has a very low detection sensitivity to ethylene gas.

  Patent Document 4 has a very high sensitivity and selectivity to NO gas, but does not respond to ethylene and is an optical measurement, so a large-scale apparatus is required.

  Therefore, an object of the present invention is to measure gases such as ethylene, which is a plant growth hormone, with high sensitivity even under humid conditions, and even after reflow treatment, even after long use. An object of the present invention is to provide a sensor that can continuously measure without deterioration of a sensitive film.

  In order to solve the above-mentioned problems, the inventors of the present application have conducted intensive studies and, as a result of repeated experiments, have found that the above-mentioned problems can be unexpectedly solved, and have completed the present invention.

That is, the present invention is as follows.
[1]
A surface stress sensor having a sensitive film containing an organic-inorganic hybrid,
The organic-inorganic hybrid includes a metal oxide (i) having a continuous chain structure formed by a chemical bond with each other,
A sensor in which an organic functional group (ii) is introduced on the surface or inside of the metal oxide.
[2]
The sensor according to [1], wherein the metal oxide (i) is silica.
[3]
Sensors of the metal oxide (i) is, with a specific surface area of 10m ² / g~1000m ² / g (1) or (2).
[4]
The sensor according to any one of [1] to [3], wherein the metal oxide (i) has a total pore volume of 0.01 to 1.52 cm ³ / g.
[5]
The sensor according to any one of [1] to [4], wherein the organic functional group (ii) contains a saturated or unsaturated carbon bond.
[6]
The organic functional group (ii) includes a functional group containing one or more atoms selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a halogen atom, a boron atom, and a phosphorus atom [1] to The sensor according to any one of [5].
[7]
The sensor according to any one of [1] to [6], wherein the organic functional group (ii) includes at least one selected from the group consisting of an unsaturated bond, a nitrogen atom, an oxygen atom, a sulfur atom, and a fluorine atom.
[8]
The sensor according to any one of [1] to [7], wherein a thermal weight loss rate of an organic component obtained by combining the metal oxide (i) and the organic functional group (ii) is 3% to 65%.
[9]
The sensor according to any one of [1] to [8], wherein the organic functional group (ii) is an organic functional group derived from a silane coupling agent.
[10]
The sensor according to any one of [1] to [9], wherein gas molecules are adsorbed and diffused on the organic functional group (ii) to generate stress, and detect gas.
[11]
The sensor according to any one of [1] to [10], wherein the sensitive film further contains (iii) metal ions and / or metal nanoparticles.
[12]
The sensor according to any one of [1] to [11], wherein the metal ion is Ag (I) and / or Cu (I).
[13]
The sensor according to any one of [1] to [12], wherein the metal ion is Ag (I).
[14]
The sensor according to any one of [1] to [13], wherein the metal nanoparticles are at least one selected from the group consisting of gold, silver, platinum, and palladium nanoparticles.
[15]
The organic-inorganic hybrid contains a bond represented by R ₁ R ₂ R ₃ SiO _1/2 (R _{1 to} R ₃ each independently represent an organic group or a hydrogen atom) [1] to [14]. One of the sensors.

  According to the present invention, a gas such as ethylene, which is a plant growth hormone, can be measured with high sensitivity even under humid conditions. It is possible to provide a sensor that can be continuously measured without deterioration.

3 is an SEM image of a sensitive film of Example 1. 13 is an SEM image of a sensitive film of Example 6. 13 is an SEM image of a sensitive film of Example 10. 5 shows an example of an optical micrograph of a chip coated with a sensitive film. The responsiveness to ethanol at 0% and 30% humidity in Example 1 is shown. 18 shows the ethylene responsiveness of the surface stress sensor of Example 24. 7 shows the response to ethanol at 0% and 30% humidity in Comparative Example 1.

  Hereinafter, an embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. It is.

  The sensor according to the present embodiment is a sensor having a sensitive film including an organic-inorganic hybrid, wherein the organic-inorganic hybrid includes a metal oxide (i) having a continuous chain structure that is mutually bonded by a chemical bond. An organic functional group (ii) is introduced on the surface or inside of the metal oxide. The sensor includes, for example, a sensor body of a type that detects a physical parameter. As physical parameters, for example, surface stress, stress, force, surface tension, pressure, mass, elasticity, Young's modulus, Poisson's ratio, resonance frequency, frequency, volume, thickness, viscosity, density, magnetic force, magnetic quantity, magnetic field, magnetic flux , Magnetic flux density, electric resistance, electric quantity, permittivity, electric power, electric field, electric charge, current, voltage, potential, mobility, electrostatic energy, capacitance, inductance, reactance, susceptance, admittance, impedance, conductance, plasmon, refractive index , Luminosity and temperature, and various other physical parameters. The sensor of the present embodiment is, for example, a sensor in which a sensitive film (also referred to as a “receptor layer”) is provided directly on the sensor body. In this sensor, a change in a physical parameter caused by the adsorption of the analyte molecule by the receptor layer is detected by the sensor body. Therefore, the sensor body that can be used in the present invention detects a change caused in the receptor layer due to the adsorption of the substance to be detected by the receptor layer formed by coating the surface of the sensor body with the material for forming the receptor layer. There is no particular limitation as long as it does. When the sensor of the present embodiment is used for, for example, a surface stress-type olfactory sensor, a receptor layer covering the surface detects a change in stress caused in the receptor layer by adsorbing a detection target substance. The surface stress type olfactory sensor outputs a signal. Further, as another type of sensor body, for example, a QCM which is a mass sensor that measures a minute change in mass by utilizing the property that when a substance is adsorbed on the electrode surface of a quartz oscillator, the resonance frequency fluctuates in accordance with the mass of the substance. When is used, a signal is output by detecting a change in mass caused by the receptor layer covering the surface adsorbing the detection target substance. Here, the term "adsorption" is used in the broadest sense including not only physical adsorption but also adsorption by chemical bonding or biochemical action.

[Organic-inorganic hybrid]
The organic-inorganic hybrid of the present embodiment includes a metal oxide (i) having a continuous chain structure bonded to each other by a chemical bond, and an organic functional group (ii) on the surface or inside of the metal oxide (i). Has been introduced.

[Metal oxide (i)]
The metal oxide (i) has a continuous chain structure that is bonded to each other by a chemical bond. Such a continuous chain structure is not limited to, for example, the continuous chain structure shown in FIG. 1, FIG. 2, or FIG. Examples of the continuous chain structure include, for example, a structure in which spherical particles are continuously connected in a straight line, a structure in which the particles are connected in a branched manner, a structure in which the particles are connected in a bent shape, and a structure in which the particles are connected in a ring shape (a “pearl necklace-shaped” structure). Or a structure in which a plurality of thread-like structures are not individually observed in a continuous spherical shape (also referred to as a “network-like structure”).

Examples of the metal oxide constituting the continuous chain structure include, for example, silica, titania, zirconia, barium titanate, zirconium titanate, strontium titanate, and the like. From the viewpoint of availability and structure controllability, silica is used. Is preferred. The silica is composed of, for example, a part of SiO ₂ , SiO _3/22 , SiO _1/2 , or a plurality thereof. The present inventors consider the reason why the use of silica improves the attenuation of the response of general gases such as ethanol, acetaldehyde, toluene, and ethylene even in a humid state as follows. However, the cause is not limited to this. The use of a silica skeleton in the continuous chain structure improves the attenuation of general gas responses such as ethanol, acetaldehyde, toluene, and ethylene even in humid conditions due to bonding to the silica skeleton and silicon atoms. It is presumed that the resulting hydroxyl group is relatively hydrophobic compared to the hydroxyl group bonded to the titania skeleton or the titanium atom.

  Such a continuous chain structure can be produced by a sol-gel method of a metal oxide precursor having a 3- or 4-functional hydrolyzable group such as alkoxy and chloro by a sol-gel method, or a commercially available product can be used. Can also. Commercial products include 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 (all of them are Nissan Chemical Products).

  The metal oxide (i) constituting the continuous chain structure is not easily defined by the primary particle diameter, assuming a general spherical shape, but the chain width can be observed by TEM / SEM with an electron microscope. it can. The chain width is 1 nm to 200 nm, preferably 1 nm to 100 nm from the viewpoint of increasing the surface area, and more preferably 1 nm to 85 nm from the viewpoint of gas responsiveness.

The specific surface area and pore volume of the metal oxide (i) constituting the continuous chain structure can be evaluated by BET measurement of nitrogen adsorption. The chain skeleton can form a larger pore volume than the spherical metal oxide due to the rigidity of the skeleton, and the large specific surface area and pore volume are caused by gas molecules inside the sensitive membrane like a surface stress sensor. It is presumed that this contributes to increasing the sensitivity of the response because it improves the accessibility of the response. The specific surface area is preferably 10m ² / g~1000m ² / g, preferably from the viewpoint of further enhancing the gas accessibility to sensitive film inside a 15m ² / g~1000m ² / g, pore more preferably the sensitivity reduction due to the elastic modulus decreases from the viewpoint of suppressing a 15m ² / g~800m ² / g by. Pore volume is preferably 0.01cm ³ /g~1.52cm ³ / g, from the viewpoint of enhancing the gas accessibility to sensitive film inside, 0.02m ² /g~1.50m ² / g it is preferably, and more preferably the sensitivity reduction due to the elastic modulus decreased by pores from the viewpoint of suppressing a 0.03m ² /g~1.00m ² / g.

[Organic functional group (ii)]
The organic functional group (ii) may be introduced, for example, by modifying the surface of the metal oxide (i) having a continuous chain structure, and a metal oxide precursor having an organic functional group and a tetrafunctional hydrolyzate may be introduced. It may be introduced by copolymerizing with a decomposable metal oxide.

The organic functional group (ii) preferably contains a saturated or unsaturated carbon bond from the viewpoint of humidity resistance, and the organic functional group (ii) is formed from the viewpoint of responsiveness to highly polar gas / odor molecules. It preferably contains a functional group containing at least one atom selected from the group consisting of a halogen atom such as a nitrogen atom, an oxygen atom, a sulfur atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a boron atom, and a phosphorus atom. . Among these, from the viewpoint of stability, the organic functional group (ii) is a functional group containing at least one atom selected from the group consisting of an unsaturated bond, a nitrogen atom, an oxygen atom, a sulfur atom, and a fluorine atom. Preferably, it contains a group. Specific examples of the organic functional group (ii) include a linear or branched hydrocarbon group which may have a substituent such as a halogen atom (for example, a linear or branched hydrocarbon group such as a 3-chloropropyl group and an octyl group). branched C _1-8 alkyl group), optionally alicyclic hydrocarbon group which may have a substituent such as a halogen atom (e.g., C _5-6 cycloalkyl groups such as cyclohexyl group), a substituent such as a halogen atom An aromatic hydrocarbon group (eg, phenyl group, pentafluorophenyl group, etc.), a vinyl group, an allyl group, a (meth) acryl group, a (meth) acryloyloxyalkyl group (eg, (meth) acryloyloxy) (Meth) acryloyloxy C _1-3 alkyl group such as propyl group), epoxy group, glycidyloxyalkyl group (for example, glycidyloxy C group such as 3-glycidyloxypropyl group) _1-3 alkyl group), (epoxycycloalkyl) alkyl group (for example, 2- (3,4-epoxycyclohexyl) ethyl group, etc.), hydroxy group, ether group, carbonyl group, carboxyl group, ester group, urethane group, Urea group, mercapto group, mercaptoalkyl group (eg, mercapto C _1-3 alkyl group such as mercaptopropyl group), sulfide group, amino group (eg, primary amino group, secondary amino group, tertiary amino group), Aminoalkyl group (for example, amino C _1-3 alkyl group such as aminopropyl group), (aminoalkylamino) alkyl group (for example, 3- (2-aminoethylamino) propyl group), imidazolyl group, imidazolylalkyl group ( For example, 3- (2-imidazolin-1-yl) propyl group), alkylaminoalkyl group (for example, - (dimethylamino) propyl), an amide group, a heterocyclic aromatic group, an oxime group, an imide group, an imine group, a halogen group, a nitrile group, a phosphonic group and a phosphoric acid group. Among them, the organic functional group (ii) is, from the viewpoint of availability, a linear or branched hydrocarbon group which may have a substituent, an alicyclic hydrocarbon group which may have a substituent, Optionally substituted aromatic hydrocarbon group, vinyl group, allyl group, (meth) acryloyloxyalkyl group, glycidyloxyalkyl group, (epoxycycloalkyl) alkyl group, mercaptoalkyl group, aminoalkyl group, ( It is preferably at least one selected from the group consisting of an aminoalkylamino) alkyl group, an imidazolylalkyl group, an alkylaminoalkyl group, and a hydroxy group. These functional groups may be used alone or in combination of two or more.

  The organic functional group (ii) is preferably an organic functional group derived from a silane coupling agent. Examples of the silane coupling agent include hydrolyzable metal oxides such as alkoxysilane and chlorosilane. Among them, the hydrolyzable metal oxide is preferably an alkoxysilane from the viewpoint of handleability and versatility of functional groups, and more preferably a trifunctional alkoxysilane from the viewpoint of reactivity.

  As the trifunctional alkoxysilane, a silane coupling agent having a methoxy group, an ethoxy group, or an isopropoxy group in the alkoxy group can be used. Commercially available silane coupling agents include phenyl trialkoxysilane, 3- (2-aminoethylamino) propyl trialkoxysilane, 3-mercaptopropyl trialkoxysilane, vinyl trialkoxysilane, cyclohexyl trialkoxysilane, 3-glycidyloxypropyl Trialkoxysilane, 2- (3,4-epoxycyclohexyl) ethyl trialkoxysilane, 3- (dimethylamino) propyl trialkoxysilane, 3- (2-imidazolin-1-yl) propyl trialkoxysilane, 3-aminopropyl Trialkoxysilane, 3- (methacryloyloxy) propyl trialkoxysilane, 3- (acryloyloxy) propyl trialkoxysilane, allyltrialkoxysilane, methyltrialkoxy Orchid, ethyl trialkoxy silane, propyl trialkoxy silane, butyl alkoxy silane, hexyl trialkoxy silane, octyl trialkoxy silane, decyl trialkoxy silane, dodecyl trialkoxy silane, octadecyl trialkoxy silane, 3-ureido propyl trialkoxy silane, nitrobenzene Amido trialkoxysilane, benzyl trialkoxysilane, cyclohexylaminopropyl trialkoxysilane, phenylaminopropyl trialkoxysilane, hexafluorophenyl trialkoxysilane, 3-chloropropyl trialkoxysilane, 3-bromopropyl trialkoxysilane, 3-pipe Radinopropyl trialkoxysilane, 3-morpholinopropyl trialkoxysilane, 3 Allyl-aminopropyl trialkoxysilane, 4-chlorophenyl trialkoxysilane, norbornyl trialkoxysilane, piperidinopropyl trialkoxysilane, and the like.

  Organic-inorganic hybrids having a continuous chain structure are mainly produced using a sol-gel method. A commercially available linear colloidal silica may be treated with a silane coupling agent, or may be produced by simultaneously condensing a silane coupling agent and a tetrafunctional alkoxysilane, triethoxysilane, or trialkoxysilane. Can be. When the chain-shaped commercially available colloidal silica is treated with a silane coupling agent, a structure in which a condensate of the silane coupling agent is attached to the surface of the metal oxide (i) shown in FIG. Is maintained. On the other hand, when a continuous chain structure is produced by simultaneous condensation of a silane coupling agent and a tetrafunctional alkoxysilane, no deposits are observed on the surface, and the functional groups are not localized inside the chain structure and on the surface. Distribution. In addition, surface hydroxyl groups remain in the continuous chain structure.

  The surface modification of the metal oxide (i) having a continuous chain structure with an organic functional group is performed by surface modification in a state of being dispersed in a dispersion medium. Specifically, for example, an organic-inorganic hybrid having a continuous chain structure is produced by a step of adding the silane coupling agent to a uniform dispersion of a metal oxide containing alcohol and water in the presence of a catalyst.

  When an organic-inorganic hybrid having a continuous chain structure is produced by simultaneous condensation of a silane coupling agent and a tetrafunctional alkoxysilane, for example, in the presence of a catalyst in a solvent containing alcohol and water, mixing, It is produced by reacting.

  From the viewpoint of controlling the reaction rates of hydrolysis and condensation, it is more preferable to hydrolyze, condense and surface-modify the silane coupling agent in the presence of a catalyst.

  Examples of the type of the catalyst include an acid catalyst and a base catalyst. For example, acid catalysts include inorganic acids and organic acids. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid, boric acid and the like. Examples of the organic acid include acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic acid, methylmalonic acid, benzoic acid, and p-aminobenzoic acid Acids, 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 and the like. Examples of the base catalyst include an inorganic base and an organic base. Examples of the inorganic base include, for example, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; lithium carbonate, potassium carbonate, and carbonic acid. Alkali or alkaline earth metal carbonates such as sodium; metal bicarbonates such as potassium bicarbonate and sodium bicarbonate; Examples of the organic base include 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, 2,6 Pyridine derivatives which may have an alkyl substituent having 1 to 4 carbon atoms, such as lutidine; These catalysts can be used alone or in combination of two or more.

  It is preferable from the viewpoint of reaction efficiency to add an amount of the catalyst that makes the pH of the reaction system in the range of 0.01 to 6.0 or pH 8 to 14. In order to further increase the efficiency, basic conditions of pH 8 to 14 are added. More preferably, the modification reaction is performed under the following conditions.

  Hydrolysis and condensation for producing a chain organic-inorganic hybrid can also be performed in an organic solvent. Examples of the organic solvent that can be used for the condensation reaction include alcohols, esters, ketones, ethers, aliphatic hydrocarbon compounds, aromatic hydrocarbon compounds, amide compounds, and the like.

  Examples of the alcohol include 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; 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 monoethyl ether, B propylene glycol monopropyl ether, mono ethers of polyhydric alcohols such as propylene glycol monobutyl ether; and the like.

  Examples of the ester include methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone, and the like. Ketones include, for example, acetone, methyl ethyl ketone, methyl isoamyl ketone and the like.

  Examples of the ether include, in addition to the monohydric alcohol monoethers, for example, 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 Polyhydric alcohol ethers in which all of the hydroxyl groups of a polyhydric alcohol such as glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and diethylene glycol diethyl ether are alkyl etherified; tetrahydrofuran; 1,4-dioxane; and anisole.

  Examples of the aliphatic hydrocarbon compound include hexane, heptane, octane, nonane, and decane.

  Examples of the aromatic hydrocarbon compound include benzene, toluene, xylene and the like.

  Examples of the amide compound include dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and the like.

  Among the above solvents, methanol, ethanol, isopropanol, butanol, etc. as alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, etc. as ketones; ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. as ethers 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 a plurality of solvents may be used in combination.

  The organic-inorganic hybrid is recovered by separating the precipitate and the gelled product by centrifugation and filtration. Although a silane coupling agent condensate that does not contribute to the continuous chain structure may exist as a residue, there is no problem that the condensate enters the sensitive film. From the viewpoint of the physical durability of the sensitive film, it is preferable that the residue is small.

  The introduction of the organic functional group can be confirmed by FT-IR or elemental analysis. It can also be confirmed by thermogravimetric reduction measurement. In order to remove the influence of the adsorbed water, the thermal weight loss rate of the organic component including the metal oxide (i) and the organic functional group (ii) from 150 ° C. to 1000 ° C. is 3% to 65% from the viewpoint of sensitivity. %, More preferably 5% to 65%, and even more preferably 5% to 55% from the viewpoint of thermal stability.

The organic-inorganic hybrid has a mono-structural unit (M unit) represented by R ₁ R ₂ R ₃ SiO _1/2 (R _{1 to} R ₃ each independently represent an organic group or a hydrogen atom). It is preferred to have. R _{1 to} R ₃ are each independently preferably a hydrocarbon group, more preferably a methyl group, a phenyl group or a vinyl group. R ₁ R ₂ R ₃ SiO _1/2 is introduced by exposing a sensor (eg, a surface stress olfactory sensor) to silazane or monochlorosilane vapor or immersing it in a liquid. It is preferable to use silazane to prevent deterioration of the surface stress sensor chip with a sensitive film due to rust, and it is preferable to perform treatment in a vapor of silazane to prevent deterioration and dissolution of the sensitive film in a liquid. By these treatments, the hydroxyl groups present on the surface of the sensitive film react with the silazane, and the hydroxyl groups are converted to R ₁ R ₂ R ₃ SiO _1/2 through a deammonification reaction, and are hydrophobized. The degree of hydrophobization is confirmed by the contact angle. When the hydrophobization is completed, the contact angle increases from 80 to 120 °, becomes hydrophobic, and the signal attenuation under humidity is eliminated by this hydrophobicity. It is estimated. The introduction can still be confirmed by XPS or TOF-SIMS.

  Examples of the silazane include 1,1,1,3,3,3-hexamethyldisilazane, 1,3-divinyl-1,1,3,3-tetramethyldisilazane, and 1,3 diphenyl1,1, 3,3-tetramethyldisilazane, 1,1,3,3-tetramethyldisilazane and the like are used.

  Performing the surface hydrophobization treatment after the application of the MSS membrane is preferable from the viewpoint of adhesion to the sensor. This is because the adhesion between the substrate and the sensitive film is mainly via the hydroxyl groups present on the surface, and it is presumed that the decrease in the number of hydroxyl groups decreases the adhesiveness.By using an organic-inorganic hybrid for the sensitive film, It can be used without being peeled off even at a reflow temperature of 260 ° C.

[(iii) Metal ions, metal nanoparticles]
It is preferable that the sensitive film further includes (iii) metal ions and / or metal nanoparticles from the viewpoint of sensitivity. Metal ions and metal nanoparticles are mixed with, for example, an organic-inorganic hybrid and applied to a surface stress sensor as a sensitive film.

  Examples of metal ions and metal nanoparticles include Ag (I), Cu (I), Cu (II), Pd (II), Ag nanoparticles, Cu nanoparticles, and palladium nanoparticles. Among these, the metal ion is preferably Ag (I) and / or Cu (I), and more preferably Ag (I). The metal nanoparticles are preferably at least one selected from the group consisting of Ag nanoparticles, Cu nanoparticles, gold nanoparticles, platinum, and palladium nanoparticles, and include gold nanoparticles, Ag nanoparticles, platinum, and palladium. More preferably, it is at least one selected from the group consisting of nanoparticles. The present inventors presume the reason why ethylene gas can be measured with high sensitivity by adding these metal ions as follows. However, the cause is not limited to this. That is, when the orbital of ethylene is efficiently coordinated with the vacant electron orbital of these metal atoms, ethylene molecules are taken into the sensitive film and a larger surface stress is generated in the sensitive film.

  The content ratio of these metal ions and / or metal nanoparticles may be 0.1 to 30 times the weight ratio of the organic-inorganic hybrid. The content ratio is preferably from 0.15 to 30 times from the viewpoint of sensitivity, and more preferably from 0.15 to 20 times from the viewpoint of adhesion to the substrate of the sensitive film, and from the viewpoint of applicability to the sensor element. , 0.15 to 15 times.

[Surface stress type (MSS) olfactory sensor]
The sensor of the present embodiment is preferably a four-point fixed piezo element type surface stress (MSS) sensor.

  Methods for coating the organic-inorganic hybrid on the surface of the sensor body (for example, the MSS sensor body) include dip coating, spray coating, spin coating, inkjet spotting, casting, and a coating method using a doctor blade.

  For application to a 300 μmφ MSS membrane, inkjet and microjet systems are preferred, and microjet application is most preferred from the viewpoint of productivity.

  The sensitive film can be produced, for example, by dispersing an organic-inorganic hybrid in an organic solvent and applying the dispersion on an 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. The concentration is preferably 0.5 to 50 g / l from the viewpoint of productivity, and more preferably 0.5 to 15 g / l from the viewpoint of suppressing nozzle clogging.

  In the present embodiment, the sensitive film may be formed by blending optional components such as particles and resin in addition to the organic hybrid in the organic hybrid. By dissolving these components in a coating solution, it can be applied to the MSS sensor surface.

  The organic solvent for dispersing the organic-inorganic hybrid may be any solvent as long as it is a dispersible solvent, and preferably has a boiling point of 80 ° C to 250 ° C. The temperature is preferably 250 ° C., and more preferably 100 ° C. to 200 ° C. in order to shorten the time required for drying and enhance productivity.

  Regarding the thickness of the coating, when the coating is performed by inkjet, it often has a coffee ring shape, and often does not have a uniform thickness. In this case, the thickness of the thinnest portion and the thickest portion of the sensitive film is 10 nm to 50 μm, and is preferably 10 nm to 30 μm in order to shorten the time required for drying and increase the productivity. It is particularly preferred that the thickness is 20 nm to 30 μm.

  In order to use the surface stress sensor MSS coated with the organic-inorganic hybrid as an olfactory sensor, it is used in the air.

  The sensor preferably detects gas by adsorbing and diffusing gas molecules on the organic functional group (ii) to generate stress.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Various physical properties of the organic-inorganic hybrid of each Example and Comparative Example and the MSS olfactory sensor coated with the chain organic-inorganic hybrid were evaluated according to the following (0) to (5).
(0) Measurement of specific surface area and total pore volume of metal oxide These measurements were obtained by a BET nitrogen adsorption method.
(1) Thermogravimetric Loss Rate The temperature was raised to 1000 ° C at 10 ° C / min in an air atmosphere by TGA, and the thermogravimetric loss at 150 ° C and 1000 ° C was defined as the organic content.
(2) Ethylene responsiveness Measured at a total flow rate of 30 sccm under 25 ° C., 100 ppm ethylene and dry nitrogen. Purging with 100 ppm of ethylene for 10 minutes / nitrogen only was repeated three times every 10 minutes, and a third signal was employed. X: No signal was observed, x: 3 μV or more was observed, Δ: 10 uV or more was observed, and Δ: 100 μV or more was observed.
(3) Physical / Chemical Stability Ethanol, toluene, water saturated steam (flow rate 30 sccm) 10 min / purge purge (under dry nitrogen) 10 min at 25 ° C. 3 times each, then deformed into a film shape by observation with an optical microscope A sample with no deformation was rated as x, and a sample with no deformation was rated as Δ.
(4) Heat resistance (reflow resistance)
A sample where peeling, deformation, cracks, etc. were observed in the sensitive film after reflow at 250 ° C. for 30 seconds was evaluated as ×, and a sample which was not observed was evaluated as Δ.
(5) Influence of Humidity Resistance Purging with ethanol at 25 ° C. and 100 ppm for 10 minutes / nitrogen only was repeated three times every 10 minutes, and a third signal was employed. A sample having a signal intensity decay rate of 25% or less under dry humidity and 30 RT% was rated as Δ, a sample with a signal intensity exceeding 25% and less than 50% as Δ, and a sample with 50% or more as ×.

<Example 1>
In a separable flask, 79.3 g of phenyltrimethoxysilane was added to 50 g of a chain colloidal silica 2-propanol dispersion IPA-UP (Nissan Chemical), 80 g of water, 20 g of 28% aqueous ammonia, and 400 g of 2-propanol, and 80 ° C. For 6 hours. After the reaction solution was air-cooled, the precipitate was isolated by centrifugation at 6000 rpm for 10 minutes. After sufficiently washing the sample with ethanol, the sample was dissolved in N, N dimethylformamide to a concentration of 1 g / ml to obtain a coating solution. Some of the samples were dried under vacuum at 80 ° C., and the thermogravimetric loss was measured. A 300 μl drop of the coating liquid was applied using a microjet at an amount of 300 pl per drop onto an MSS surface arranged on a hot plate at 80 ° C. to obtain a sensitive film. An optical micrograph of the applied MSS is shown in FIG. 4 as an example of the applied sensitive film. As an example, FIG. 5 shows a response signal result with respect to 100 ppm of ethanol at a humidity of 0% and a humidity of 30%. Further, Table 1 summarizes the results of the above measurements (0) to (5).

<Example 2>
Example 1 was repeated except that the addition amount of phenyltrimethoxysilane was changed to 76.4 g and 26.4 g. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 3>
120 g of ethanol, 8.59 g of phenyltriethoxysilane, 9.3 g of tetraethoxysilane, and 3.6% of 28% aqueous ammonia were mixed and left at room temperature until gelation. The gelation was separated by filtration, the sample was sufficiently washed with ethanol, and then dissolved with N, N dimethylformamide to a concentration of 1 g / ml to obtain a coating solution. Some of the samples were dried under vacuum at 80 ° C., and the thermogravimetric loss was measured. 300 drops of the coating solution were applied using a microjet in an amount of 300 pl per drop onto the MSS surface arranged on a hot plate at 80 ° C. Table 1 summarizes the results of the above measurements (0) to (5).

<Example 4>
The procedure was the same as in Example 3 except that the amount of ethanol added was changed to 60 g instead of 120 g. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 5>
Example 1 was repeated except that 79.3 g of phenyltrimethoxysilane was added and 25.4 g of vinyltriethoxysilane was added. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 6>
Example 3 was carried out in the same manner as in Example 3 except that 6.8 g of vinyltriethoxysilane was added instead of adding 8.59 g of phenyltriethoxysilane. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 7>
Example 3 was carried out in the same manner as in Example 3 except that 6.8 g of vinyltriethoxysilane was added instead of adding 8.59 g of phenyltriethoxysilane, and 180 g was used instead of 120 g of ethanol. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 8>
Instead of adding 79.3 g of phenyltrimethoxysilane, 29.5 g of 3-aminopropyltriethoxysilane was added, and the obtained precipitate was dissolved in propylene glycol monomethyl ether instead of N, N-dimethylformamide. The procedure was the same as in Example 1 except that a coating solution was obtained. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 9>
Instead of 8.59 g of phenyltriethoxysilane, 7.91 g of 3-aminopropyltriethoxysilane was added, and the resulting precipitate was dissolved in propylene glycol monomethyl ether instead of N, N-dimethylformamide to form a coating solution. Except having obtained, it carried out similarly to Example 4. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 10>
Instead of adding 8.59 g of phenyltriethoxysilane, 7.91 g of 3-aminopropyltriethoxysilane was added, and the resulting precipitate was dissolved in propylene glycol monomethyl ether instead of N, N-dimethylformamide. The procedure was the same as in Example 3 except that a coating solution was obtained. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 11>
Example 1 was repeated except that 31.8 g of 3-mercaptopropyltriethoxysilane was added instead of adding 79.3 g of phenyltrimethoxysilane. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 12>
Example 4 was repeated except that 8.51 g of 3-mercaptopropyltriethoxysilane was added instead of adding 8.59 g of phenyltriethoxysilane.

<Example 13>
Example 1 was repeated except that 79.3 g of phenyltrimethoxysilane was added and 36.9 g of octyltriethoxysilane was added.

<Example 14>
The same procedure as in Example 1 was carried out except that 27.2 g of cyclohexyltrimethoxysilane was added instead of adding 79.3 g of phenyltrimethoxysilane.

<Example 15>
Example 1 was repeated except that 27.2 g of allyltriethoxysilane was added instead of adding 79.3 g of phenyltrimethoxysilane.

<Example 16>
Example 1 was repeated except that instead of adding 79.3 g of phenyltrimethoxysilane, 38.7 g of 3- (methacryloyloxy) propyltriethoxysilane was added.

<Example 17>
Example 1 was repeated except that 37.1 g of 3-glycidyloxypropyltriethoxysilane was added instead of adding 79.3 g of phenyltrimethoxysilane.

<Example 18>
Example 1 was repeated, except that 98.6 g of 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane was added instead of adding 79.3 g of phenyltrimethoxysilane.

<Example 19>
Instead of adding 79.3 g of phenyltrimethoxysilane, 35.3 g of 3- (2-aminoethylamino) propyltriethoxysilane was added, and the obtained precipitate was replaced with N, N-dimethylformamide by propylene. Example 1 was repeated except that a coating solution was obtained by dissolving in glycol monomethyl ether.

<Example 20>
The procedure was the same as Example 1 except that instead of adding 79.3 g of phenyltrimethoxysilane, 109.8 g of 3- (2-imidazolin-1-yl) propyltriethoxysilane was added.

<Example 21>
Example 1 was repeated except that 79.3 g of phenyltrimethoxysilane was added and 83.0 g of 3- (dimethylamino) propyltrimethoxysilane was added.

<Example 22>
The same procedure as in Example 1 was performed, except that 6 g of phenyltrimethoxysilane and 23.4 g of 3-chloropropyltriethoxysilane were mixed and added instead of adding 79.3 g of phenyltrimethoxysilane.

<Example 23>
Example 1 was repeated except that 79.3 g of phenyltrimethoxysilane was added and 14 g of phenyltrimethoxysilane and 20.2 g of pentafluorophenyltrimethoxysilane were mixed and added.

<Example 24>
The sample of Example 1 applied on the MSS is treated by exposing it to the vapor of 1,1,1,3,3,3-hexamethyldisilazane for 24 hours, and then cured (cured) at 150 ° C. for 1 hour. Was. Table 1 shows the results of the above measurements (1) to (5).

<Example 25>
An AgBF ₄ -containing coating solution obtained by dissolving 10 mg of AgBF ₄ in 10 ml of the coating solution of Example 1 was coated on a hot plate at 80 ° C. with 300 drops per drop using a microjet in an amount of 300 pl per drop. Was applied on the surface of the MSS arranged in the above. Table 1 summarizes the results of the above measurements (1) to (5). FIG. 6 shows the measurement results of the ethylene responsiveness as an example.

<Example 26>
10 mg of Pd (Aldrich, nanopower <25 nm particle) was dissolved in 10 ml of the coating solution of Example 1, and dispersed by ultrasonication. 300 drops of the Pd-containing coating solution obtained in this manner were applied using a microjet in an amount of 300 pl per drop on the MSS surface arranged on a hot plate at 80 ° C. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 27>
The sensitive film applied on the MSS surface of Example 25 was treated by exposing it to the vapor of 1,1,1,3,3,3-hexamethyldisilazane for 24 hours, and then cured at 150 ° C. for 1 hour ( Cure). Table 1 summarizes the results of the above measurements (1) to (5).

<Example 28>
The sensitive film applied on the MSS surface of Example 25 was treated by being exposed to 1,1,3,3-tetramethyldisilazane vapor for 24 hours, and then cured (cured) at 150 ° C. for 1 hour. . Table 1 summarizes the results of the above measurements (1) to (5).

<Example 29>
The sensitive film applied on the MSS surface of Example 25 was treated by exposing it to the vapor of 1,3-diphenyl-1,1,3,3-tetramethyldisilazane for 24 hours, and then at 150 ° C. for 1 hour. It was cured (cured). Table 1 summarizes the results of the above measurements (1) to (5).

<Example 30>
The sensitive film applied on the MSS surface of Example 25 was treated by exposing it to the vapor of 1,3-divinyl-1,1,3,3-tetramethyldisilazane for 24 hours, and then at 150 ° C. for 1 hour. It was cured (cured). Table 1 summarizes the results of the above measurements (1) to (5).

<Example 31>
An AgBF ₄ -containing coating solution obtained by dissolving 10 mg of AgBF ₄ in 10 ml of the coating solution of Example 20 was coated on a hot plate at 80 ° C. with 300 drops per drop using a microjet in an amount of 300 pl per drop. Was applied on the surface of the MSS arranged in the above.

<Example 32>
30 drops of an AgBF ₄ -containing coating solution obtained by dissolving 100 mg of AgBF _{4 in} 10 ml of the coating solution of Example 20 at a volume of 300 pl per drop using a microjet were placed on a hot plate at 80 ° C. Was applied on the surface of the MSS arranged in the above. Table 1 summarizes the results of the above measurements (1) to (5).

<Example 33>
The sensitive film applied on the MSS surface of Example 31 was treated by exposing it to 1,1,1,3,3,3-hexamethyldisilazane vapor for 72 hours, and then cured at 150 ° C. for 1 hour ( Cure). Table 1 summarizes the results of the above measurements (1) to (5).

<Example 34>
30 drops of the phenyl silicone condensate-containing coating solution obtained by dissolving 10 mg of the phenyl silicone condensate in 10 ml of the coating solution of Example 1 were dropped at 80 ° C. using a microjet in an amount of 300 pl per drop. It was applied on the MSS surface arranged on a hot plate. Table 1 summarizes the results of the above measurements (1) to (5).

<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 of phenyltrimethoxysilane and titanium tetraisopropoxide (TTIP) in an aqueous solution of ammonia-based isopropanol (IPA) in which octadecylamine (ODA) was dissolved. The above synthesis reaction was performed using a Teflon (registered trademark) microreactor having a micrometer-sized Y-shaped channel. There are four precursor solutions: solution 1: phenyltrimethoxysilane / IPA, solution 2: H ₂ O / IPA / ammonia, solution 3: TTIP / IPA, and solution 4: H ₂ O / IPA. Up to the same volume. The precursor solution was simultaneously sent at a constant rate by a syringe pump. The solution 1 and the solution 2 and the solution 3 and the solution 4 were mixed in a parallel microreactor, and the liquid discharged from both reactors was further mixed in another microreactor to form one reaction liquid. The reaction solution was discharged into a separately prepared precursor solution 5: ODA / H2O / IPA, and stirred at a constant speed until the discharge was completed. Thereafter, the mixture was allowed to stand at room temperature to obtain a nanoparticle dispersion. After the reaction solution was air-cooled, 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 on a MSS surface arranged on a hot plate at 80 ° C., using a microjet, 300 drops per drop in an amount of 300 pl. As an example, the response signal to ethanol 100 ppm at 0% humidity and 30% humidity was evaluated as x because signal attenuation due to 80% humidity was observed as shown in FIG.

<Comparative Example 2>
A coating solution was prepared by diluting 2-propanol dispersion IPA-UP (Nissan Chemical) with N, N-dimethylformamide to 1 g / ml. 300 drops of the coating solution were applied using a microjet in an amount of 300 pl per drop onto the MSS surface arranged on a hot plate at 80 ° C. Since the signal decay was 90% at a humidity of 30%, it was evaluated as x.

<Comparative Example 3>
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 on a MSS surface arranged on a hot plate at 80 ° C., using a microjet, 300 drops per drop in an amount of 300 pl. No signal to ethylene 100 ppm was observed at all, and at 25 ° C., ethylene, ethanol, acetaldehyde, and toluene were measured three times at 500 ppm for 10 minutes / purge for 10 minutes. Observation with an optical microscope revealed that the film shape was deformed. And

<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 drops of the coating solution were applied using a microjet in an amount of 300 pl per drop onto the MSS surface arranged on a hot plate at 80 ° C. No signal to ethylene 100 ppm was observed at all, and after measuring ethylene, ethanol, acetaldehyde, and toluene 500 ppm 10 minutes / purge 10 minutes three times at 25 ° C., the film was observed by an optical microscope. did.

  The sensor of the present invention has a high sensitivity to, for example, ethylene, ethanol, and acetaldehyde, and has an effect of showing a high response even under humidity, and thus can be suitably used in the field of food transport management.

Claims (15)

A surface stress sensor having a sensitive film containing an organic-inorganic hybrid,
The organic-inorganic hybrid includes a metal oxide (i) having a continuous chain structure formed by a chemical bond with each other,
A sensor in which an organic functional group (ii) is introduced on the surface or inside of the metal oxide.   The sensor according to claim 1, wherein the metal oxide (i) is silica. Sensor according to claim 1 or 2 having a specific surface area of the metal oxide (i) ^{is, 10m 2 / g~1000m 2 / g} . Wherein the metal oxide (i) is, the sensor according to claim 1, having a total pore volume of 0.01~1.52cm ³ / g.   The sensor according to any one of claims 1 to 4, wherein the organic functional group (ii) contains a saturated or unsaturated carbon bond.   The organic functional group (ii) includes a functional group containing at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a halogen atom, a boron atom, and a phosphorus atom. 6. The sensor according to any one of items 5 to 5.   The organic functional group (ii) according to any one of claims 1 to 6, wherein the organic functional group (ii) contains at least one selected from the group consisting of an unsaturated bond, a nitrogen atom, an oxygen atom, a sulfur atom, and a fluorine atom. sensor.   The sensor according to any one of claims 1 to 7, wherein a thermal weight loss rate of an organic component obtained by combining the metal oxide (i) and the organic functional group (ii) is 3% to 65%.   The sensor according to any one of claims 1 to 8, wherein the organic functional group (ii) is an organic functional group derived from a silane coupling agent.   The sensor according to any one of claims 1 to 9, wherein gas molecules are adsorbed and diffused on the organic functional group (ii) to generate stress and detect gas.   The sensor according to any one of claims 1 to 10, wherein the sensitive film further comprises (iii) metal ions and / or metal nanoparticles.   The sensor according to any one of claims 1 to 11, wherein the metal ion is Ag (I) and / or Cu (I).   The sensor according to any one of claims 1 to 12, wherein the metal ion is Ag (I).   The sensor according to any one of claims 1 to 13, wherein the metal nanoparticles are at least one selected from the group consisting of gold, silver, platinum, and palladium nanoparticles. The organic-inorganic hybrid contains a bond represented by R ₁ R ₂ R ₃ SiO _1/2 (R _{1 to} R ₃ each independently represent an organic group or a hydrogen atom). Or the sensor according to claim 1.