JP7269837B2 - sensor - Google Patents

Description

The present invention relates to sensors.

Some sensors have a detection part (receptor) that enables highly sensitive and highly selective detection of a substance to be detected. A wide variety of substances such as self-assembled membranes, monolayers, DNA/RNA, proteins, antigens/antibodies, and polymers are used as receptors. At this time, receptors are required to sense various substances to be detected with favorable sensitivity.

Patent Document 1 describes a sensor in which a sensor body is coated with a porous material or a granular material, and the specimen molecules are detected by changes in physical parameters caused by the adsorption of the specimen molecules by the porous material or the granular material. there is
Patent Document 2 discloses a gas sensing element that has a gas sensing portion and detects a gas to be sensed based on a change in electrical resistance of the gas sensing portion, wherein the gas sensing portion is made of cerium oxide, and the gas to be sensed is is a gas of at least one of an oxygen-containing organic compound and a sulfur-containing compound.
Patent document 3 has a sensitive part made of a sensitive material in which a water-insoluble, flexible polymer material is mixed with a soluble polymer that is responsive to humidity, and changes in conductivity of the sensitive part are measured. A humidity sensor is described that detects humidity or condensation by
Patent Document 4 describes a humidity sensor in which a humidity-sensitive film is formed on a piezoelectric element via thin-film electrodes, and the humidity-sensitive film is a porous glass thin film. ing.

WO2016/121155 JP 2010-002335 A JP-A-11-101766 JP-A-62-291541

In the technique described in Patent Document 1, the electric signal is greatly attenuated except in a dry atmosphere, and the environment in which it can be used is greatly restricted.
In the technique described in Patent Document 2, substances to be detected are limited to the gases described above.
In the techniques described in Patent Documents 3 and 4, the substance to be detected is limited to humidity (water) only.

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 detection of a substance to be detected with high sensitivity. To provide a sensor capable of measuring a highly sensitive gas with high sensitivity and having less deterioration of a receptor even after reflow treatment and after 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 receptor to which a substance to be detected adheres,
A sensor wherein, in the distribution of the total occupancy with respect to the logarithmic area ratio calculated by subjecting the receptor to the following measurement, the logarithmic area ratio A that gives the maximum of the total occupancy is -4.1 or more. :
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy.
[2]
The sensor according to [1], wherein the logarithmic area ratio A is -3.5 or more.
[3]
A sensor having a receptor to which a substance to be detected adheres,
In the distribution of the total occupancy with respect to the logarithmic area ratio calculated by subjecting the receptor to the following measurement, the logarithmic area where the accumulation of the total occupancy from the smaller logarithmic area ratio is 60% A sensor with a rate B of -4.1 or greater:
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy.
[4]
The sensor according to [3], wherein the logarithmic area ratio B is -3.5 or more.
[5]
The sensor according to any one of [1] to [4], wherein the receptor comprises an organic-inorganic hybrid.
[6]
The sensor of [5], wherein said organic-inorganic hybrid is represented by RSiO3 _/2 , wherein said R comprises at least one organic functional group.
[7]
The sensor of [7], wherein the organic functional group comprises at least one aromatic ring.
[8]
The sensor according to any one of [1] to [7], wherein the receptor further contains a filler.
[9]
The sensor according to any one of [1] to [8], wherein the maximum thickness of the receptor is 30 μm or less.
[10]
The sensor according to any one of [1] to [9], wherein the sensor is a surface stress sensor.

According to the present invention, a substance to be detected can be measured with high sensitivity, and in particular, even under high humidity, highly hydrophilic gases such as ethanol and aldehyde can be measured with high sensitivity. , it is possible to provide a sensor with little deterioration of the receptor even after long-term use.

An example of an optical micrograph of a receptor-coated sensor is shown. 1 is a scanning electron microscope (SEM) image of the receptor surface of Example 1. FIG. Cross-sectional images (left column), binarized cross-sectional images (middle column), and quadtree spatial division images (right column) of arbitrary three points (upper to lower) of the receptor in Example 1. be. 1 is a graph plotting total occupancy versus logarithmic area fraction of receptors of Example 1. FIG. 2 is a graph plotting total occupancy accumulation versus log area percent of receptors of Example 1. FIG. 4 is an SEM image of the receptor surface of Example 2. FIG. Cross-sectional images (left column), binarized cross-sectional images (middle column), and quadtree spatial division images (right column) of arbitrary five points (upper to lower) of the receptor of Example 2 be. 2 is a graph plotting total occupancy versus logarithmic area fraction of receptors of Example 2. FIG. 2 is a graph plotting total occupancy accumulation versus log area percent of receptors of Example 2. FIG. 4 is an SEM image of the receptor surface of Example 3. FIG. Cross-sectional images (left column), binarized cross-sectional images (middle column), and quadtree spatial division images (right column) of arbitrary three points (upper to lower) of the receptor of Example 3. be. 2 is a graph plotting total occupancy versus logarithmic area fraction of receptors of Example 3. FIG. 2 is a graph plotting total occupancy accumulation versus log area percent of receptors of Example 3. FIG. 4 is an SEM image of the receptor surface of Comparative Example 1. FIG. Cross-sectional images (left column), binarized cross-sectional images (middle column), and quadtree spatial division images (right column) of three arbitrary points (top to bottom) on the receptor surface of Comparative Example 1 is. 2 is a graph plotting the total occupancy against the logarithmic area ratio of receptors of Comparative Example 1. FIG. 10 is a graph plotting the cumulative total occupancy versus the logarithmic area fraction of the receptors of Comparative Example 1. FIG.

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.

A sensor according to a first aspect of the present embodiment (hereinafter also referred to as a "first sensor") is a sensor having a receptor to which a substance to be detected adheres, wherein the receptor is subjected to the following measurements. In the distribution of the total occupancy with respect to the logarithmic area ratio calculated by:
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy.
Since the first sensor is configured as described above, highly hydrophilic gases such as ethanol and aldehyde can be measured with high sensitivity even under humid conditions. , even after long-term use, continuous measurement can be performed without deterioration of the receptor.
A sensor according to a second aspect of the present embodiment (hereinafter also referred to as a "second sensor") is a sensor having a receptor to which a substance to be detected adheres, wherein the receptor is subjected to the following measurements. In the distribution of the total occupancy with respect to the logarithmic area ratio calculated using the above, the logarithmic area ratio B at which the accumulation of the total occupancy from the smaller logarithmic area ratio is 60% is -4. is greater than or equal to 1:
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy.
The second sensor can also measure highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under humid conditions. Measurement can be continued without deterioration of the body.
Hereinafter, unless otherwise specified, the term "sensor of the present embodiment" includes the first sensor and the second sensor, and the term "receptor of the present embodiment" includes the first and a receptor at a second sensor.

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 receptor is provided directly on a sensor body. That is, the sensor of this embodiment can detect changes in physical parameters caused by the adsorption and internal diffusion of the analyte molecules by the sensor body. As described above, the sensor body that can be used in the present embodiment detects a change caused by the receptor arranged on its surface by adsorbing and internal diffusion of the substance to be detected. , is not particularly limited.

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 a receptor in this embodiment on the surface of the electrode, the mass change caused by the receptor adsorbing the substance to be detected is detected by the sensor body. Detect and output a signal. Various conductive materials can be applied as the electrodes of the QCM. When the receptor in this embodiment is to have conductivity, the receptor 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.

[Receptor]
The receptor in the sensor of the present embodiment can induce a signal change by adsorption and internal diffusion of adsorbates such as odor molecules and gas molecules. Membrane-shaped receptors, in particular, are also referred to as "sensitive membranes".
In this embodiment, the components of the receptor are not particularly limited, but from the viewpoint of sensing highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under high humidity, and further after reflow treatment and after long-term use. From the viewpoint of maintaining the performance of the receptor even if there is, it is preferable that an organic-inorganic hybrid and/or a filler, which will be described later, is contained.

The receptor in the first sensor has a logarithmic area ratio A of -4.1 or more when subjected to the above-described measurement. Since the logarithmic area ratio A is -4.1 or more, the first sensor can measure highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under humid conditions. Furthermore, even after reflow treatment and long-term use, the measurement can be continued without deterioration of the receptor. In the present embodiment, from the viewpoint of film stability, the logarithmic area ratio A is preferably −3.5 or more, more preferably −3.3 or more from the viewpoint of sensitivity, and from the viewpoint of humidity resistance. to -3.2 or more is more preferable. In the first sensor, the logarithmic area ratio A in at least one of the surface or cross section at an arbitrary position of the receptor may satisfy the above numerical range. It is preferable that the maximum value of the logarithmic area ratio A in the surface or cross section (3 fields or more) at 3 or more points of the above satisfies the above numerical range, and the maximum value of the logarithmic field area ratio A in 5 or more fields of view is the above numerical value. It is more preferable to satisfy the range. The logarithmic area ratio A can be adjusted within the above range by, for example, adjusting the ratio of the structure represented by the filler to RSiO _3/2 and the amount of the organic functional group, which will be described later.

Taking the case of observing the cross section of the receptor as an example, the logarithmic area ratio and the total occupancy are values obtained as follows. First, the receptor is cut in the thickness direction or the width direction, and the resulting cross section is observed with an SEM at a magnification of 100,000 times, for example. In the obtained SEM image, quadtree space division is performed in order to distinguish between void portions and dense portions of the cross section. As preprocessing for quadtree space division, a threshold value is determined for each small region of the SEM image, and binarization processing is performed for bright and dark portions by adaptive threshold processing. Subsequently, a 3×3 spatial filtering process is performed on the binarized image to clarify dark portions (gap portions). After that, quadtree space division is performed, division is performed until the number of black pixels (gap pixels) included in each area of the division is 1, and the number and area of dense parts that do not contain gap pixels are obtained. . In this way, the quadrilateral group corresponding to the dense portion is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated. The methods for calculating the logarithmic area ratio and the total occupation ratio are as described above, and more specifically, they can be obtained by the method described in Examples below.

Further, the receptor in the second sensor has a logarithmic area ratio B of −4.1 or more when subjected to the above-described measurement. Since the logarithmic area ratio B is -4.1 or more, the second sensor can measure highly hydrophilic gases such as ethanol and aldehyde with high sensitivity even under humid conditions. Furthermore, even after reflow treatment and long-term use, the measurement can be continued without deterioration of the receptor. Also, the adhesiveness to the sensor main body is improved. In the present embodiment, the logarithmic area ratio B is preferably −3.5 or more from the viewpoint of sensitivity, and more preferably −3.3 or more from the viewpoint of humidity resistance. In the second sensor, the logarithmic area ratio B in at least one of the surface or cross section at any position of the receptor may satisfy the above numerical range. It is preferable that the maximum value of the logarithmic area ratio B in the surface or cross section (3 fields or more) at 3 or more points of the above satisfies the above numerical range, and the maximum value of the logarithmic field area ratio B in 5 or more fields of view is the above numerical value. It is more preferable to satisfy the range. The logarithmic area ratio B can be adjusted within the above range, for example, by adjusting the ratio of the structure represented by the filler to RSiO _3/2 and the amount of the organic functional group, which will be described later.

The fact that the maximum value of the total occupancy is large and that the total occupancy is on the high logarithm area ratio side indicates that the structure has fewer voids, or that the structure has a wide dense region with dense and continuous voids. On the low logarithm area ratio side, it means that there are more voids and the voids are uniformly distributed.
A large distribution of the total occupancy with respect to the logarithmic area ratio means that the void distribution is highly uneven. In this embodiment, fewer voids are preferable in terms of sensitivity, adhesiveness, and humidity resistance.
From the above viewpoint, in the sensor of the present embodiment, at least one of the logarithmic area ratio A and the logarithmic area ratio B obtained by subjecting the receptor to the above-described measurement satisfies each of the above ranges, and the logarithmic area It is preferable that both the ratio A and the logarithmic area ratio B satisfy the respective ranges described above.

The receptor in this embodiment preferably contains an organic-inorganic hybrid. The organic-inorganic hybrid in the present embodiment preferably has 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 content of the organic-inorganic hybrid in the receptor is not particularly limited, but is preferably 50% by mass or more.

In this embodiment, the organic functional group preferably contains one or more aromatic rings. When an aromatic ring is contained, sensitivity and humidity resistance tend 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 organic functional group 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 A spacer structure such as a group, an imine group, or the like may be interposed, but from the viewpoint of responsive sensitivity, it is preferable that the organic functional group is directly bonded to the Si atom in the organic-inorganic hybrid without interposing these spacers. preferable.
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.

Examples of trifunctional alkoxysilanes include, but are not limited to, silane coupling agents having alkoxy groups such as methoxy, ethoxy, and isopropoxy groups.
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 receptor on the sensor body to surface elemental analysis such as SEM-EDX, XPS, and ATR.
In the organic-inorganic hybrid of the present embodiment, the organic functional group content is preferably 75% by mass or less, more preferably 65% by mass or less.

[Filler]
The receptor in this embodiment preferably 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 thereof include, but are not limited to, polystyrene, polymethyl methacrylate, polyphenylene oxide and other polymer beads, acrylic latex and other spherical particles, metal nitrides such as silicon nitride, silica, zirconia, titania, zinc oxide, oxide Metal oxides such as aluminum and tin oxide, complex metal compounds such as barium titanate, strontium titanate, and ITO, inorganic metal fillers such as gold, silver, copper, palladium, platinum, iron, and aluminum, carbon nanotubes, graphene, and carbon It can contain one or more selected from carbon materials such as black. The shape of the filler in the present embodiment is not particularly limited, and forms a unique tissue structure/structure such as a spherical shape, a beaded shape, a chain shape, a hollow shape, an ellipsoidal shape, a fibrous shape, a rod shape, a cylindrical shape, a needle shape, a plate shape, etc. You may have

From the viewpoint of dispersibility and coatability, the filler in the present embodiment is preferably an inorganic filler. From the same point of view as above, in the present embodiment, metal oxides such as silica, zirconia, titania, and alumina, and inorganic metal fillers such as gold, silver, copper, palladium, platinum, iron, and aluminum are preferable, and they can be used under humidity. Metal oxides such as silica and zirconia are more preferable because the effect of signal attenuation due to moisture is small. From the viewpoint of economy, silica is more preferable, and spherical or linear silica is even more preferable. 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 the dispersibility of the ink, that is, improving the coating properties of the ink jet, etc., the average primary particle size is preferably 100 μm or less, and the sensitivity is improved. It is more preferably 500 nm or less from the viewpoint of improvement, 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. For example, when the filler is produced by emulsion polymerization, it is conceivable that a structure represented by RSiO _3/2 may be obtained on the filler side. 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.

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; 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;

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 receptor 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 substance to be detected and the stability of the receptor, it should be 75% by mass or less. is preferred, and 65% by mass or less is more preferred.

If the receptor in the present embodiment has a film shape, the measurement accuracy is stabilized. Therefore, the preferred film thickness may be a shape in which the organic-inorganic hybrid has a uniform film thickness distribution, or a film thickness at the end portion may be thick. It may have a distributed coffee ring shape. A film having a coffee ring shape does not deteriorate in shape even when exposed to high-concentration VOC vapor, has excellent structural stability, and has a higher sensitivity than a film structure consisting of a flat structure. Therefore, it is preferable. The reason for this is considered as follows, but it is not intended to be limited to the following. If the sensor is a surface stress sensor, and a coffee ring type film is placed on the surface stress sensor, more film volume is placed near the piezo, so the stress due to the deformation is transmitted to the piezo element more efficiently. It is considered that high sensitivity can be achieved. As a coffee ring type, a cross-sectional profile between two points on the diameter of the membrane formed in a circular shape is obtained, and from the cross-sectional profile, it is confirmed that the thickness of the central part is 80% or less of the thickness of the maximum part. It is preferable from the viewpoint of sensitivity reproducibility, more preferably 60% or less from the viewpoint of sensitivity, and more preferably 40% or less from the viewpoint of maximizing response sensitivity. In the case of a coffee ring shape, the thickness of the thinnest portion at the central portion of the 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 receptor 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.

[Surface stress sensor]
The sensor of the present embodiment can be applied to, for example, a surface stress sensor, and more specifically can be used as a membrane-type surface stress (MSS) sensor. In this case, the receptor covering at least part of the surface of the sensor main body absorbs the substance to be detected, and the stress change induced in the receptor is detected, and the main body outputs a signal. The surface stress sensor is preferably a four-point fixed piezoelectric element type surface stress sensor.

[Sensor manufacturing method]
The method of manufacturing the sensor of this embodiment is not particularly limited, but it can be manufactured by various methods for forming receptors on the sensor body. The receptor 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 sensor main body with the coating liquid. An inkjet device can be suitably used when applying the coating liquid onto the chip of the sensor. By manufacturing using an inkjet device, the productivity is excellent, and the reproducibility of the sensor provided with the obtained film is excellent. According to the inkjet device, droplets of a coating liquid are ejected, the droplets are applied onto the sensor, and a film-shaped receptor, that is, 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 (for example, the MSS sensor body) is not particularly limited, but for example, dip coating, spray coating, spin coating, inkjet spotting, casting, doctor blade, etc. coating methods.

Inkjet or microjet methods are preferred for coating on the membrane of the 300 μmφ MSS sensor, and microjet coating is more preferred from the viewpoint of productivity.
The receptor can be produced, for example, by dispersing the 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 receptor in this embodiment may contain additives such as arbitrary particles, ionic compounds, resins, and low-molecular-weight compounds in addition to organic-inorganic hybrids. A sensor having a receptor containing the additive can be obtained by, for example, blending the additive into a coating liquid and applying the mixture to the surface of the sensor body.

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 the MSS olfactory sensor of each example and comparative example were evaluated according to the following (1) to (8).

(1) Measurement of Void Parameter of Receptor Dicing was performed to form a cross-section in the thickness direction of the receptor on the sensor body. After fixing this as a sample on a processing table, it was processed by FIB Milling under the following conditions, and SEM observation was performed. 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°
Magnification 100,000 times

A receptor layer was cut out from an image obtained by cross-sectional SEM observation, and voids present in the cross section of the receptor were extracted. For the extraction, we used the fact that in the obtained image, the area around the gap has a bright contrast due to the edge effect, and the gap itself has a dark contrast. , By setting a threshold value for each small area of the image, adaptive thresholding is a method that enables binarization that is resistant to changes in the light source environment within the image. did The threshold at this time was set to 131 in grayscale. In the extracted image of the obtained voids, a 3 × 3 filter is applied so as not to miss the voids of one pixel. A quadtree space partitioning was performed. performing quadtree space division until the number of void pixels (black pixels) included in each region of the division becomes one, and classifying the quadrilateral groups corresponding to the dense portions that do not contain void pixels by area; The logarithmic area ratio and the total occupancy were calculated as follows.

(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image was taken as the area ratio, and the common logarithm of the value was taken as the logarithmic area ratio.
(total occupancy)
The total area value of the quadrangles having the same area in the quadrilateral group was expressed as a ratio when the area of the image was set to 1, and the value was defined as the total occupancy.

(Logarithmic area ratio A and logarithmic area ratio B)
The logarithmic area ratio was plotted on the horizontal axis and the total occupation ratio was plotted on the vertical axis. In addition, the logarithmic area ratio was plotted on the horizontal axis and the accumulation of the total occupancy was plotted on the vertical axis. In the distribution of the total occupancy with respect to the logarithmic area ratio obtained as described above, the logarithmic area ratio A that gives the maximum of the total occupancy and the accumulation of the total occupancy from the smaller logarithmic area ratio is 60%, and the logarithmic area ratio B was obtained. For each receptor, the above measurement was performed for at least 3 points, or at least 5 points if a distribution of voids was observed, and the logarithmic area ratio A and the logarithmic area ratio B were determined as the maximum values.

(2) Identification of Organic Functional Group Species in Organic-Inorganic Hybrid Based on the following conditions, the organic functional group in the organic-inorganic hybrid was identified by measuring the receptor on the main body of the sensor by a microscopic ATR method.
(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 receptor scraped from the sensor was dried in air at 100° C., then allowed to cool 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 receptor By observing the uncoated part of the receptor and the maximum thickness part of the receptor in the sensor using a confocal laser microscope (VK09700 Violet Laser (manufactured by Keyence)), the thickness of the receptor was determined. was measured. That is, a cross-sectional profile between two points on the diameter of a receptor formed in a substantially circular shape was obtained, an uncoated portion and a 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 the value is ◎ when the value is 20% or less, ○ when the value is 21% to 40% or less, △ when 41% or more and less than 60%, and 61% or more. .

(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)
When peeling, deformation, cracks, etc. were observed in the receiver after reflowing at 250° C. for 30 seconds, it was evaluated as x, and when it was not observed, it was 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. By applying 30 droplets of the coating liquid in an amount of 300 pL per droplet using an inkjet device onto the surface of the sensor body for the MSS sensor placed on a hot plate at 80 ° C., four receptors (sensitivity A MSS sensor on which a membrane) was formed was obtained. Its appearance was the same as that shown in FIG.
Next, the results of SEM observation of the surface of the receptor in Example 1 are shown in FIG. Further, cross-sectional SEM images of the receptor at three arbitrary points were acquired by the above method (1), and after binarization, quadtree space division was performed (FIG. 3). When plotting the total occupancy rate and the total occupancy rate accumulation after the quadtree space division against the logarithmic area occupancy rate, the maximum logarithmic area occupancy rate A and logarithmic area occupancy rate B in the three cross sections were -0.60, respectively. and −1.10 (FIGS. 4, 5). Thus, almost no voids were observed in the receptor in Example 1.
Further, the maximum thickness of the MSS sensor according to Example 1 was measured based on the method (4) above.
Furthermore, the influence of humidity resistance was examined based on the method (5) above, and a maximum amplitude of 550 μV was obtained at a humidity of 0% (under dry conditions) 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. No deformation, peeling, cracks, etc. were observed in the tests (6) and (7) above, so the rating was ◯.
In the same manner as the method described above, the MSS sensor was also evaluated for the following examples and comparative examples.

<Example 2>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 13.5 g.
The results of SEM observation of the surface of the receptor in Example 2 are shown in FIG. In addition, cross-sectional SEM images of five arbitrary points of the receptor were acquired by the method (1) above, and after binarization, quadtree space division was performed (FIG. 7). In Example 2, since there were regions where there were almost no gaps and regions where there were gaps, it was decided to take cross sections at arbitrary five points. When the total occupancy and total occupancy after quadtree space division were plotted against the logarithmic area occupancy, the maximum logarithmic area occupancy A and logarithmic area occupancy B in the five cross sections were -3.00, respectively. and −3.00 (FIGS. 8 and 9). As described above, in the receptor of Example 2, more voids were observed than in Example 1, and the 5-point variation was also large, indicating that the voids also had a distribution.

<Example 3>
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. An MSS sensor in which four receptors (sensitive membranes) were formed was obtained by coating the surface of a sensor body for an MSS sensor (same as in Example 1) placed on a hot plate at 80°C. Its appearance was the same as that shown in FIG.
The results of SEM observation of the surface of the receptor in Example 3 are shown in FIG. In addition, cross-sectional SEM images of the receptor at three arbitrary points were acquired by the method (1) above, and after binarization, quadtree space division was performed (FIG. 11). When plotting the total occupancy rate and the total occupancy rate accumulation after the quadtree space division against the logarithmic area occupancy, the maximum logarithmic area occupancy A and logarithmic area occupancy B in the three cross sections are -3.60, respectively. and −3.70 (FIGS. 12, 13). Thus, it was shown that the receptor in Example 3 had more voids than in Example 2, but the void distribution was small.

<Example 4>
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 5>
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 6>
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 7>
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 8>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 37.6 g of 4-chlorophenyltriethoxysilane.

<Example 9>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 30.4 g of 4-methoxyphenyltrimethoxysilane.

<Example 10>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 31.5 g of 3-furyltriethoxysilane.

<Example 11>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 33.9 g of 3-thienyltriethoxysilane.

<Example 12>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 23.3 g of 4-aminophenyltrimethoxysilane.

<Example 13>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was replaced with 29 g of p-tolyltrimethoxysilane.

<Example 14>
Example 1 was followed except that 27.1 g of phenyltrimethoxysilane was changed to 27.2 g of naphthalenetrimethoxysilane.

<Example 15>
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 16>
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 17>
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 18>
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 19>
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 20>
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 21>
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 22>
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 23>
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 24>
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 25>
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 26>
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 27>
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. By applying the coating liquid to the surface of the sensor body for the MSS sensor (similar to Example 1) placed on a hot plate at 80 ° C. with 300 droplets in an amount of 300 pL per droplet using a microjet , an MSS sensor with four receptors (sensitive membranes) was obtained. Its appearance was the same as that shown in FIG.

<Example 28>
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. By applying the coating liquid to the surface of the sensor body for the MSS sensor (similar to Example 1) placed on a hot plate at 80 ° C. with 30 drops of 300 pL per drop using a microjet , an MSS sensor with four receptors (sensitive membranes) was obtained. Its appearance was the same as that shown in FIG.

<Example 29>
37 g of ethanol, 2.6 g of tetraethoxysilane, 9.0 g of phenyltriethoxysilane, and 2.26 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. By applying the coating liquid to the surface of the sensor body for the MSS sensor (similar to Example 1) placed on a hot plate at 80 ° C. with 30 drops of 300 pL per drop using a microjet , an MSS sensor with four receptors (sensitive membranes) was obtained. Its appearance was the same as that shown in FIG.

<Example 30>
Example 10 was followed except that 10.1 g of 3-furyltriethoxysilane was used.

<Example 31>
Example 10 was followed except that 17.3 g of 3-furyltriethoxysilane was used.

<Example 32>
150 droplets of the coating liquid of Example 1 were placed on a hot plate at 80 ° C. on a hot plate at 80 ° C. using an inkjet device. By coating, an MSS sensor in which four receptors (sensitive membranes) were formed was obtained. Its appearance was the same as that shown in FIG.

<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. By applying the coating liquid to the surface of the sensor body for the MSS sensor (similar to Example 1) placed on a hot plate at 80 ° C. with 300 droplets in an amount of 300 pL per droplet using a microjet , an MSS sensor with four receptors (sensitive membranes) was obtained. Its appearance was the same as that shown in FIG.
The results of SEM observation of the surface of the receptor in Comparative Example 1 are shown in FIG. In addition, cross-sectional SEM images of any three points of the receptor were acquired by the method (1) above, and after binarization, quadtree space division was performed (FIG. 15). When plotting the total occupancy rate and the total occupancy rate accumulation after the quadtree space division against the logarithmic area occupancy, the maximum logarithmic area occupancy A and logarithmic area occupancy B in the three cross sections were -4.15, respectively. and −4.15 (FIGS. 16, 17). As described above, it was found that the receptor in Comparative Example 1 was more porous and had smaller and more uniformly dispersed voids than the receptor in Example.

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

Claims (10)

A sensor having a receptor to which a substance to be detected adheres,
A sensor wherein, in the distribution of the total occupancy with respect to the logarithmic area ratio calculated by subjecting the receptor to the following measurement, the logarithmic area ratio A that gives the maximum of the total occupancy is -4.1 or more. :
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy. 2. The sensor of claim 1, wherein the logarithmic area ratio A is -3.5 or more. A sensor having a receptor to which a substance to be detected adheres,
In the distribution of the total occupancy with respect to the logarithmic area ratio calculated by subjecting the receptor to the following measurement, the logarithmic area where the accumulation of the total occupancy from the smaller logarithmic area ratio is 60% A sensor with a rate B of -4.1 or greater:
[measurement]
In an image obtained by observing the surface or cross section of the receptor at an arbitrary position with a scanning electron microscope, quadtree spatial division is performed to distinguish between void portions and dense portions of the surface or cross section. The quadrilateral group corresponding to the dense portion obtained by the quadtree space division is classified by area, and the logarithmic area ratio and the total occupation ratio are calculated as follows.
(logarithmic domain area ratio)
A value obtained by dividing each area of the quadrilateral group by the area of the image is defined as an area ratio, and the common logarithm thereof is taken as a logarithmic area ratio.
(total occupancy)
A value expressed as a ratio of the total area value of the quadrilaterals having the same area in the quadrilateral group to the area of the image being 1 is defined as a total occupancy. 4. The sensor of claim 3, wherein the logarithmic area ratio B is -3.5 or more. The sensor of any one of claims 1-4, wherein the receptor comprises an organic-inorganic hybrid. 6. The sensor of claim 5, wherein said organic-inorganic hybrid is represented by RSiO3 _/2 , wherein said R comprises at least one type of organic functional group. 7. The sensor of Claim 6, wherein the organic functional group comprises at least one aromatic ring. The sensor of any one of claims 1-7, wherein the receptor further comprises a filler. A sensor according to any one of the preceding claims, wherein the maximum thickness of the receptor is 30 µm or less. A sensor according to any preceding claim, wherein the sensor is a surface stress sensor.

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