JP7519833B2 - Gas sensor, gas sensor sensitive member, and gas sensing method - Google Patents

Description

This disclosure relates to a gas sensor, a sensing member for a gas sensor, and a gas sensing method.

Various types of gas sensors, such as semiconductor, catalytic combustion, infrared spectroscopy, and nanomechanical types, are known as means for detecting trace components contained in gas. Of these, catalytic combustion and semiconductor gas sensors are widely used.
Catalytic combustion gas sensors are used to detect combustible gases (see, for example, Patent Document 1). Semiconductor gas sensors use a heated metal oxide semiconductor as a sensitive material and measure gas concentration based on the change in resistance of the sensitive material (see, for example, Patent Documents 2 and 3).

JP 2009-075137 A JP 2000-275201 A JP 2015-175835 A

Gas sensors may not be able to perform adequately if the gas contains a large amount of water vapor. For example, if a catalytic combustion type gas sensor is energized with humidified water, reaction product water, etc. attached to the detection element, localized temperature distribution may become uneven on the surface of the sensitive film, which may lead to element destruction or reduced sensitivity. Therefore, the gas sensor described in Patent Document 1 has a built-in heater to prevent condensation. Semiconductor type gas sensors have very high sensitivity and can detect gases at concentrations on the order of ppb depending on the combination of the gas to be detected and the sensitive material, but it is known that the output depends on the absolute humidity. Therefore, the gas sensor described in Patent Document 2 improves the selectivity of the target gas by, for example, silicone-treating the surface of the metal oxide semiconductor. Patent Document 3 proposes a method for compensating for the effect of humidity on a MEMS (Micro Electro Mechanical Systems) type metal oxide semiconductor gas sensor.

As mentioned above, gas sensors still have room for improvement in terms of suitability for high-humidity environments. In particular, sensors that detect trace substances using microfabrication techniques, such as nanomechanical sensors and MEMS sensors, have various gas detection principles, such as mass change, electrical resistance change, conductivity change, capacitance change, and stress change. In addition, since multiple types of sensitive materials can be used in one sensor, the target gas selectivity can be increased even in mixed gas analysis containing multiple components. However, when such sensors are used in high-humidity environments, it is currently difficult to avoid non-specific adsorption of water molecules.
In view of the above problems, an object of one embodiment of the present disclosure is to provide a gas sensor that exhibits excellent sensitivity even under high humidity conditions, a sensitive member for a gas sensor, and a gas sensing method.

Means for solving the above problems include the following embodiments.
<1> A gas sensor comprising a sensing part including a sensitive member, the contact angle of water on a surface of the sensitive member that comes into contact with gas being 75° or more.
<2> The gas sensor according to <1>, wherein the sensing portion detects at least one change selected from the group consisting of a volume, a mass, a stress, an electrical resistance, and an electrical conductivity of the sensitive member.
<3> The gas sensor according to <1> or <2>, wherein the sensor member includes a resin. <4> The gas sensor according to any one of <1> to <3>, wherein the sensor member has a thickness of 2 nm to 100,000 nm.
<5> The gas sensor according to any one of <1> to <4>, wherein the sensitive member has an arithmetic mean roughness Ra of 1 nm to 500 nm.
<6> The gas sensor according to any one of <1> to <5>, wherein the sensitive member has an elastic modulus of 1×10 ⁸ Pa to 1×10 ¹⁰ Pa.
<7> The gas sensor according to any one of <1> to <6>, further comprising a purge mechanism.
<8> The gas sensor according to any one of <1> to <7>, further comprising a protective member arranged around a portion other than the sensing portion.
<9> A sensitive member for a gas sensor, the contact angle of water on the surface in contact with gas being 75° or more.
<10> A gas sensing method comprising the step of bringing a gas into contact with a sensitive member having a surface in contact with the gas with a water contact angle of 75° or more.

The present disclosure provides a gas sensor, a sensitive film for a gas sensor, and a gas sensing method that exhibit excellent sensitivity even under high humidity conditions.

1 is a cross-sectional view illustrating an example of the configuration of a sensing portion of a gas sensor. FIG. 2 is a diagram showing the shape of a cantilever-type sensor used in the examples. 1 is a graph showing the amount of gas adsorption in a saturated water vapor atmosphere in an example. 1 is a graph showing the amount of gas adsorption in an acetone atmosphere in an example.

The following describes in detail the form for implementing the present disclosure. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and do not limit the present disclosure.

In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced by the upper or lower limit value of another numerical range described in stages, or may be replaced by a value shown in the examples.
In this disclosure, when a material contains multiple substances corresponding to each component, the amount of each component in the material means the total amount of the multiple substances present in the material, unless otherwise specified.

<Gas sensor>
One embodiment of the present disclosure is a gas sensor including a sensing unit including a sensitive member, the sensor having a surface of the sensitive member that comes into contact with gas with a water contact angle of 75° or more.

The gas sensor includes a sensing member having a surface where the sensing portion comes into contact with gas, the surface having a water contact angle of 75° or more.
The reason why the contact angle of water on the surface of the sensitive member that comes into contact with the glass is 75° or more and therefore the sensitive member exhibits excellent sensitivity even under high humidity conditions is presumed to be as follows.
When the contact angle of water is 75° or more, the responsiveness of the sensing member to water molecules in the gas is sufficiently low, while the speed of dissolution, diffusion, desorption, etc. of molecules other than water is faster than that of water, and the difference between the responsiveness to water molecules and the responsiveness to molecules other than water becomes clearer. As a result, good sensitivity can be obtained even when gas sensing is performed under high humidity conditions.

In this disclosure, a gas sensor refers to a device that is intended to obtain information about components in a gas, and the specific content of the information is not particularly limited. For example, it may be detection of components in a gas, measurement of concentration, or determination of the ratio of multiple components.

The sensing unit of the gas sensor detects at least one change selected from the group consisting of the volume, mass, stress, electrical resistance, and electrical conductivity of the sensitive member. The change in the sensitive member occurs due to, for example, adsorption of molecules in the gas onto the surface of the sensitive member, absorption of molecules into the sensitive member, sorption which is a combination of adsorption and absorption, diffusion of molecules inside the sensitive member, desorption of molecules from the sensitive member, etc. In the present disclosure, these phenomena may be collectively referred to as "adsorption, etc."
The change in the sensitive member may be either an increase or a decrease.

It is preferable that the sensitive material included in the sensing unit has a property in which at least one selected from the group consisting of volume, mass, stress, electrical resistance, and electrical conductivity changes due to the adsorption of molecules in the gas, etc.

From the viewpoint of the sensitivity of the gas sensor, the greater the degree of change in the sensitive member, the better. Therefore, the greater the amount of adsorption of molecules in the gas that causes a change in the sensitive member, the better. For example, a sensitive member that absorbs or sorbs molecules in the gas is more preferable than a sensitive member that adsorbs molecules in the gas only on its surface, and a sensitive member that sorbs molecules in the gas is even more preferable.

There are no particular limitations on the specific method by which the sensing unit detects changes in the sensitive member. Examples include a quartz crystal oscillator method, a piezoelectric method such as PZT (lead zirconate titanate), an impedance method, an ion conduction method, a capacitance method, a piezoresistance method, and an antigen-antibody reaction method.

The sensing unit may include multiple types of sensitive members. For example, the sensing unit may include multiple types of sensitive members having different responsiveness to the detection target. By including multiple types of sensitive members having different responsiveness to the detection target, the selectivity to the detection target can be increased, and the sensitivity can be further improved.
When the sensing unit includes multiple types of sensitive members, the water contact angle on the surface of all of the sensitive members that come into contact with gas may be 75° or more, or the water contact angle on the surface of only a portion of the sensitive members that come into contact with gas may be 75° or more.
Examples of gas sensors that can have a plurality of types of sensitive members arranged in the sensing portion include MEMS sensors and nanomechanical sensors.

From the viewpoint of reducing the influence of water vapor and improving sensitivity under high humidity conditions, the contact angle of water on the surface of the sensor that comes into contact with gas is preferably 80° or more, more preferably 85° or more, and even more preferably 90° or more.
The upper limit of the contact angle of water on the surface of the sensing member that comes into contact with the gas is not particularly limited, and may be, for example, 150° or less. From the viewpoint of suppressing a situation in which the contact angle of water is too high, the responsiveness of water is lost and the responsiveness of other molecules cannot be accurately detected using water as a reference, the contact angle of water is preferably 120° or less, and more preferably 100° or less.
In the present disclosure, the water contact angle of the sensitive member is measured by the method (sessile drop method) described in the Examples.

From the viewpoint of reducing the influence of water vapor and improving the sensitivity under high humidity, the critical surface tension of the surface of the sensor member in contact with the gas is preferably 40 dynes/cm or less, more preferably 38 dynes/cm or less, even more preferably 37 dynes/cm or less, and particularly preferably 35 dynes/cm or less. The lower limit of the critical surface tension of the surface of the sensor member in contact with the gas is not particularly limited, and may be, for example, 15 dynes/cm or more.
In this disclosure, the critical surface tension of the sensitive member is measured by the Zismann plot method.

From the viewpoint of the sensitivity of the gas sensor, the thickness of the sensitive member is preferably 2 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, even more preferably 15 nm or more, and even more preferably 20 nm or more.
From the viewpoint of keeping the time required for adsorption of molecules in the gas within an acceptable range, the thickness of the sensitive member is preferably 100,000 nm or less, more preferably 70,000 nm or less, even more preferably 50,000 nm or less, and particularly preferably 30,000 nm or less.

In this disclosure, the thickness of the sensitive member refers to the dimension perpendicular to the surface of the sensitive member that comes into contact with the gas. If the thickness of the sensitive member is not constant, the maximum value is taken as the thickness of the sensitive member.

From the viewpoint of obtaining a stable water contact angle, it is preferable that the arithmetic mean roughness Ra of the surface of the sensor member that comes into contact with the gas is 1 nm to 500 nm.
In the present disclosure, the arithmetic mean roughness Ra of the surface of the sensitive member that comes into contact with the gas is measured by the method described in the examples.

From the viewpoint of the response strength of the sensing part to changes in the sensitive member, the elastic modulus of the sensitive member is preferably 1×10 ⁸ Pa or more, and from the viewpoint of the load on the substrate of the gas sensor, the elastic modulus of the sensitive member is preferably 1×10 ¹⁰ Pa or less.

In this disclosure, the elastic modulus of the sensitive member is measured by the method described in the Examples.

The material of the sensory member is not particularly limited and can be selected from a variety of materials. The sensory member may be made of one material or a combination of two or more materials.

From the viewpoint of the sensitivity, film-forming properties, etc. of the gas sensor, it is preferable that the sensitive member contains a resin.
The types of resin include synthetic resins such as thermoplastic resins, thermosetting resins, and photocurable resins, and naturally occurring resins such as biopolymers.

Examples of thermoplastic resins include polyolefin resins (e.g., polyethylene, polypropylene, polyisobutylene, polystyrene, polyvinyl chloride, etc.), polyolefin waxes (e.g., polyethylene oligomers, polypropylene oligomers, etc.), polysulfide resins, polyvinylidene fluoride resins, polyvinyl fluoride resins, polytetrafluoroethylene resins, polycarbonate resins, thermoplastic polyester resins, polyamide resins, polyimide resins, ABS (Acrylonitrile Butadiene Styrene) resins, elastomers (e.g., polyolefin elastomers, hydrogenated styrene block copolymers, hydrogenated styrene random copolymers, etc.), super engineering plastics (e.g., polyphenylene sulfide, polyamide imide, polyether sulfone, polyether ether ketone, etc.), syndiotactic polystyrene, etc. The thermoplastic resin may be a copolymer compound consisting of two or more types of comonomers, a graft polymerization compound, or a block polymerization compound synthesized by a living radical polymerization method, etc.

Examples of thermosetting or photocurable resins include unsaturated polyester resins, phenolic resins, urea resins, polyurethane resins, melamine resins, silicone resins, alkyd resins, and thermosetting polyimides. When the sensitive member contains a thermosetting or photocurable resin, the sensitive member may be formed by mixing a monomer and an initiator before curing, filling the mixture into the storage space immediately thereafter, and curing the mixture by heat or light.

The sensor may contain additives such as inorganic materials, such as metals and ceramics, carbon materials, and low molecular weight compounds (such as paraffin).

Inorganic materials include glass fiber, single crystal silicon, silicon nitride, silicon carbide, and inorganic fillers. Inorganic fillers include amorphous fillers (e.g., calcium carbonate, silica, kaolin, clay, titanium oxide, barium sulfate, zinc oxide, magnesium oxide, lanthanum oxide, cerium oxide, zirconium oxide, hydrotalcite, aluminum hydroxide, alumina, magnesium hydroxide, etc.), plate-like fillers (e.g., talc, mica, montmorillonite, glass flakes, etc.), needle-like fillers (e.g., wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, xonotlite, aluminum borate, etc.), conductive fillers (e.g., metal powder, metal flakes, carbon black, carbon nanotubes, etc.), perovskite compounds (strontium titanate, etc.), glass beads, glass powder, apatite, hydroxyapatite, and zeolite. The surface of the inorganic filler may be coated with carbon or the like, or may be subjected to a silane coupling treatment or the like.

Carbon materials include carbon fiber, activated carbon, carbon nanotubes, carbon nanohorns, graphene, graphite, etc.

The sensor may include a synthetic porous material such as a metal organic framework (MOF). The metal organic framework may be called a porous coordination polymer. For example, the metal organic framework may be Basolite (registered trademark) C300 (manufactured by BASF).

When the sensory member contains a resin, the proportion of the resin is preferably 50% to 100% by mass of the sensory member, more preferably 70% to 100% by mass, and even more preferably 80% to 100% by mass.

When the sensitive member contains a resin, the contact angle of water on the surface of the sensitive member that comes into contact with the gas is affected by the type of resin, its physical properties such as density and glass transition temperature (Tg), and the type of secondary components, etc., so it is preferable to select these so as to obtain the desired contact angle.

Specific methods for increasing the water contact angle of a sensitive material include, for example, a method of designing and synthesizing a resin so that many hydrophobic groups (e.g., hydrocarbon groups such as alkyl groups and aryl groups) are introduced into the molecular structure of the resin, and a method of adding a carbon material or a highly hydrophobic inorganic material (e.g., single crystal silicon, silicon nitride, etc.). Specific methods for decreasing the water contact angle of a sensitive material include, for example, a method of designing and synthesizing a resin so that many hydrophilic groups (hydroxyl groups, carboxyl groups, etc.) are introduced into the molecular structure of the resin, and a method of adding a highly hydrophilic additive such as glass fiber.

The sensitive member may be made of the same material or multiple different materials. When made of multiple different materials, the surface of the sensitive member that comes into contact with the gas may be made of different materials from the other parts.

When the sensing unit includes multiple types of sensitive members, the material of each sensitive member may be selected from the materials described above depending on the desired characteristics.

The shape of the sensitive member in the sensing portion is not particularly limited as long as it has at least a portion of a surface that comes into contact with the gas.
Fig. 1 is a cross-sectional view showing an example of the shape of a sensory member in a sensing unit. In a sensing unit 10 shown in Fig. 1(a), a sensory member 1 is in the form of a film disposed on a surface of a support 2. In a sensing unit 10 shown in Fig. 1(b), a sensory member 1 is accommodated in a groove formed in the support 2.

When the sensing unit has a sensitive member and a support, the material of the support is not particularly limited. For example, it may be an inorganic material such as a metal, semiconductor, or glass, or an organic material such as a resin.

There are no particular limitations on the method for forming the sensory member on the surface of the support, and any ordinary film-forming method can be used. For example, the sensory member material described above can be soaked in an organic solvent as necessary and then formed into a film by immersion, CVD (Chemical Vapor Deposition), spin coating, inkjet, dispenser, spray coating, gravure printing, or the like.

If necessary, the gas sensor may include a mechanism other than the sensing portion.
For example, a purge mechanism for refreshing the measurement environment may be provided, such as a blower mechanism, a heating mechanism, or a pump mechanism for ventilation.

If necessary, the gas sensor may include a protective member disposed around the portion other than the sensing portion, which can protect the portion other than the sensing portion from moisture, light, dust, and the like.
The protective member may be provided, for example, to seal electronic components other than the sensing unit (for example, electronic components provided in the control mechanism, analysis mechanism, monitoring mechanism, etc. described below) to prevent them from being exposed to external moisture, etc.
As the protective member, for example, a known sealing material (such as an epoxy-based sealing material) can be used.

If necessary, the gas sensor may be equipped with a control mechanism for controlling the operation of the gas sensor, an analysis mechanism for analyzing the information obtained by the sensing unit, a monitoring mechanism for monitoring the state of the measurement environment, etc.

The gas sensor is not particularly limited in its applications, but taking advantage of its excellent sensitivity even under high humidity conditions, it is more suitable for use in gas sensing applications in high humidity environments. For example, the gas sensor may be used in an environment with a relative humidity of 60% or more, a relative humidity of 70% or more, or a relative humidity of 75% or more.

Specific applications of gas sensors include detection of generated gases (odor components, harmful substances, etc.) during water and sewage treatment, detection of generated gases in pipes, septic tanks, settling tanks, aeration tanks, activated sludge tanks, etc. in industrial wastewater and sewage facilities, detection of fuel (hydrogen) leakage to the oxygen electrode side of fuel cells, detection of harmful components and generated gases in exhaust gases from internal combustion engines, detection of odors or harmful components in exhaust gases from food waste processors, detection of exhaust gases generated at power generation facilities such as thermal power plants and biomass power plants, detection of generated gases in the manufacturing process of chemical products and processed products, detection of gases generated due to changes in freshness and quality from foods such as fresh produce, fruits and vegetables, processed products, and beverages, detection of biological gases such as exhaled gases and skin gases from living organisms (humans, livestock, animals, etc.), detection of gases emitted from plants and soil, and environmental gas analysis in automobiles, factories, garbage disposal sites, garbage dumps, landfills, indoors, etc.
Further examples of applications include the detection of carbon monoxide, city gas, propane gas, etc. indoors, the detection of harmful components during oil and natural gas mining, the detection of harmful components in fumigation gases, the detection of odor components during the production and storage of food and beverages, and the detection of atmospheric gas components during the carburizing and carbonitriding treatment of metal parts.

<Sensing material>
One embodiment of the present disclosure is a sensitive member for a gas sensor, the sensitive member having a surface in contact with gas that has a contact angle of water of 75° or more.

The gas sensor sensitive material has a water contact angle of 75° or more on the surface that comes into contact with gas. This allows gas sensing to be performed with high sensitivity even under high humidity conditions.

The details and preferred aspects of the sensing member for the gas sensor are the same as those of the sensing member included in the sensing portion of the gas sensor described above.

<Gas sensing method>
One embodiment of the present disclosure is a gas sensing method including a step of contacting a gas with a sensitive member having a surface in contact with the gas that has a contact angle of water of 75° or more.

The sensing member used in the above method has a water contact angle of 75° or more on the surface that comes into contact with the gas. Therefore, gas sensing can be performed with high sensitivity even if the gas in contact with the sensing member contains a large amount of water vapor.

The details and preferred aspects of the sensitive member used in the above method are the same as those of the sensitive member included in the sensing portion of the above gas sensor.
The sensitive member used in the above method may be included in the sensing portion of the gas sensor described above.

The present disclosure will be explained below using examples, but the present disclosure is not limited in any way to these examples.

<Preparation of Sensitive Materials and Measurement of Their Physical Properties>
The following resin solution for the sensitive member was dropped onto a cover glass, and a spin coater was used to prepare sensitive members of Examples 1 and 2 and Comparative Examples 1 and 2, and the physical properties were measured. The results are shown in Table 1.

Example 1: 4 vol% xylene solution of polyethylene (PE, Sigma-Aldrich, weight average molecular weight 35,000) Example 2: 15 vol% NMP (N-methyl-2-pyrrolidone) solution of polyvinylidene fluoride (PVDF, Sigma-Aldrich, weight average molecular weight 180,000) Comparative Example 1: 20 vol% NMP solution of polymethyl methacrylate (PMMA, Fujifilm Wako Pure Chemical Industries, Ltd., weight average molecular weight 15,000) Comparative Example 2: 20 vol% aqueous solution of polyethyleneimine (PEI, Fujifilm Wako Pure Chemical Industries, Ltd., weight average molecular weight 70,000)

The measurement conditions for each physical property of the sensory material are as follows:

The water contact angle was measured by the drop method using a contact angle meter (Kyowa Interface Science Co., Ltd., DM-SA) at constant temperature and humidity of 25°C and 50% RH (relative humidity) by using a microsyringe to drop 1 microliter of distilled water onto the surface of the sensitive member.

The thickness of the sensitive material was measured using a white light interferometric non-contact film thickness measuring device (FILMETRICS(R)).

The arithmetic surface roughness Ra of the sensitive member was measured in accordance with JIS B 0601:2013. Specifically, it was measured using a high-magnification surface roughness profile measuring instrument, Surfcom 920A, manufactured by Tokyo Seimitsu Co., Ltd.

The elastic modulus of the sensitive component was measured using a hardness tester (Shimadzu Corporation, Dynamic Ultra-Micro Hardness Tester "DUH-W201S") at 23°C and 50% RH using a diamond pyramid indenter.

<Evaluation of gas detection performance>
Using the resin solutions used for producing the sensitive members in Examples 1 and 2 and Comparative Examples 1 and 2, cantilevers for evaluating gas detection performance were produced as follows.
A silicon on insulator (SOI) substrate (device layer 5 μm/BOX layer 1 μm/handle layer 275 μm, orientation <100>, p-type SOI with carrier density of about 1016/ ^cm3 ) was used as a support, and a cantilever was fabricated by two photolithography processes. Specifically, the device layer was etched by a first Deep RIE (Reactive Ion Etching) process, and the handle layer of 275 μm was etched by a second Deep RIE process.
Next, the _SiO2 of the BOX layer was etched by a BHF etching process to produce a cantilever 100 consisting of a cantilever portion 11 with a width of 10 μm and a length of 300 μm from the surface layer and a stage portion 12 with a diameter of 250 μm at the tip (see FIG. 2). Although not shown, the stage portion 12 is on the same plane as the device layer.
A film-like sensitive member was formed by applying the resin solution used in the examples and comparative examples to the stage 12 of the cantilever 100. As the application device, a tabletop fine application device NRS-3018 (Fine Pasting System) manufactured by NTN Corporation and a high repeat application needle HR-100 (application needle diameter 100 μm) were used.

Using a Polytec MSA-500 Micro System Analyzer, the resonance frequency of the cantilever was measured before and after application of the resin solution, and the mass of the sensitive member was measured from the change. As a reference, the resonance frequency was measured in an _N2 atmosphere and in a saturated water vapor atmosphere. It was found that the cantilever had water adsorption equivalent to less than 10 Hz. The formula for calculating the mass m from the resonance frequency is generally shown in the following (Formula 1) and Formula 2. In the formula, m* represents the effective mass, k represents the spring constant, and f represents the resonance frequency. The spring constant was 0.45 N/m.

(Gas adsorption amount in saturated water vapor atmosphere)
As described above, the time-dependent resonance frequency was measured when the _N2 atmosphere was switched to a saturated water vapor atmosphere, and the mass of gas adsorbed by each sensor was calculated. Since the amount of sensor on the stage varies depending on the sample, the amount of gas adsorbed per nanogram of sensor was calculated (Shift ng/ng). The results are shown in Figure 3.

(Gas adsorption amount in acetone atmosphere)
As described above, the resonance frequency over time was measured when the _N2 atmosphere was switched to a 5 vol% acetone atmosphere, and the mass of gas adsorbed by each sensor was calculated. Since the amount of sensor on the stage varies depending on the sample, the amount of gas adsorbed per nanogram of sensor was calculated (Shift ng/ng). The results are shown in Figure 4.

As shown in the results of Figures 3 and 4, the sensitive members of Examples 1 and 2, which have a water contact angle of 75° or more, have extremely low responsiveness to saturated water vapor, but show responsiveness to acetone. Moreover, Examples 1 and 2 each showed a different response profile to acetone.
The sensitive members of Comparative Example 1 and Comparative Example 2, which have a contact angle of water smaller than 75°, were responsive to saturated water vapor and acetone. Comparative Example 1 and Comparative Example 2 also showed different response profiles to saturated water vapor and acetone, respectively.
From these findings, it was found that when the contact angle of water on the sensitive member is greater than 75°, water vapor and acetone can be distinguished and detected, that is, acetone can be distinguished and detected under high humidity conditions.

1...sensing member, 2...support, 10...sensing part, 11...beam part, 12...stage part, 100...cantilever

Claims (17)

A gas sensor comprising a sensing unit including a sensitive member, the contact angle of water on the surface of the sensitive member that comes into contact with the gas being 75° or more, the sensitive member including a resin, and the proportion of the resin in the sensitive member being 50% by mass to 100% by mass. A gas sensor comprising a sensing unit including a sensitive member, the contact angle of water on the surface of the sensitive member that comes into contact with the gas being 75° or more, and the sensitive member including a resin (excluding silane polymers). A gas sensor comprising: a sensing unit including a sensitive member, the contact angle of water on a surface of the sensitive member that comes into contact with a gas being 75° or more, the sensitive member including a resin, the resin including polyolefin resin, polysulfide resin, polyvinylidene fluoride resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, polycarbonate resin, thermoplastic polyester resin, polyamide resin, polyimide resin, ABS resin , polyphenylene sulfide, polyethersulfone, polyetheretherketone, phenol resin, urea resin, polyurethane resin, melamine resin or alkyd resin. A gas sensor comprising a sensing unit including a sensitive member, the sensitive member having a surface that comes into contact with gas with a contact angle of water of 75° or more, and a modulus of elasticity of the sensitive member being 1×10 ⁸ Pa to 1×10 ¹⁰ Pa. The gas sensor according to any one of claims 1 to 4, wherein the sensing unit detects at least one change selected from the group consisting of the volume, mass, stress, electrical resistance, and electrical conductivity of the sensitive member. The gas sensor according to any one of claims 1 to 5, wherein the sensing member has a thickness of 2 nm to 100,000 nm. The gas sensor according to any one of claims 1 to 6, wherein the sensing member has an arithmetic mean roughness Ra of 1 nm to 500 nm. The gas sensor according to any one of claims 1 to 7, further comprising a purge mechanism. The gas sensor according to any one of claims 1 to 8, further comprising a protective member arranged around the area other than the sensing portion. A sensing element for a gas sensor, the surface of which in contact with gas has a water contact angle of 75° or more, contains a resin, and the proportion of said resin in the sensing element is 50% to 100% by mass. A sensing component for a gas sensor, the surface of which has a water contact angle of 75° or more and contains a resin (excluding silane polymers). A sensitive component for a gas sensor, the surface of which that comes into contact with gas has a water contact angle of 75° or more, and the sensitive component contains a resin, the resin being selected from the group consisting of polyolefin resin, polysulfide resin, polyvinylidene fluoride resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, polycarbonate resin, thermoplastic polyester resin, polyamide resin, polyimide resin, ABS resin , polyphenylene sulfide, polyethersulfone, polyetheretherketone, phenol resin, urea resin, polyurethane resin, melamine resin and alkyd resin. A sensitive member for a gas sensor, the sensitive member having a surface in contact with gas that has a water contact angle of 75° or more and an elastic modulus of 1×10 ⁸ Pa to 1×10 ¹⁰ Pa. A gas sensing method comprising a step of contacting a gas with a sensitive member having a water contact angle of 75° or more on a surface in contact with the gas, the sensitive member containing a resin, and the proportion of the resin in the sensitive member is 50% by mass to 100% by mass. A gas sensing method comprising a step of contacting a gas with a sensitive member having a water contact angle of 75° or more on a surface in contact with the gas, the sensitive member including a resin (excluding silane polymers). A gas sensing method comprising a step of bringing a gas into contact with a sensitive member having a water contact angle of 75° or more on a surface in contact with the gas, the sensitive member comprising a resin, the resin comprising polyolefin resin, polysulfide resin, polyvinylidene fluoride resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, polycarbonate resin, thermoplastic polyester resin, polyamide resin, polyimide resin, ABS resin , polyphenylene sulfide, polyethersulfone, polyetheretherketone, phenol resin, urea resin, polyurethane resin, melamine resin or alkyd resin. A gas sensing method comprising the step of bringing a gas into contact with a sensitive member having a surface in contact with the gas that has a water contact angle of 75° or more, the sensitive member having an elastic modulus of 1×10 ⁸ Pa to 1×10 ¹⁰ Pa.

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