Fluorocarbon gas sensors, fluorocarbon gas sensor systems, and polymers for fluorocarbon gas sensors

Abstract

To provide a compact, low-power fluorocarbon gas sensor that can safely detect fluorocarbon gases. [Solution] A fluorocarbon gas sensor comprising a polymer whose capacitance changes in the presence of a fluorocarbon gas, and a detection unit that detects the potential change based on the capacitance change.

Description

[Technical Field]

[0001] This disclosure relates to fluorocarbon gas sensors, fluorocarbon gas sensor systems, and polymers for fluorocarbon gas sensors. [Background technology]

[0002] There is a demand for sensors that can detect fluorocarbon gases in real time. Two main types of fluorocarbon gas sensors are known: the non-dispersive infrared absorption (NDIR) method, which uses infrared light to induce resonance in specific molecules and detects specific gases from changes in infrared transmittance due to these molecular vibrations; and the hot-wire semiconductor method, which uses a heater to adsorb oxygen onto the surface of a metal oxide, stopping the flow of electrons, and then detects changes in electrical resistance caused by the release of oxygen into the air due to the influence of the detected gas.

[0003] On the other hand, odor sensors have been reported that include two or more sensor elements, each having a substance adsorption membrane for adsorbing odor substances and a signal conversion unit for determining the adsorption status of the odor substances onto the substance adsorption membrane, wherein the substance adsorption membrane contains a conductive polymer and a dopant that alters the material properties of the conductive polymer, and each of the two or more sensor elements has a different ratio of the dopant to the conductive polymer in its substance adsorption membrane (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2017 / 085939 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, no polymers capable of adsorbing fluorocarbon gases and detecting their presence have been reported. Conventional NDIR sensors for fluorocarbon gases are generally expensive and tend to consume a lot of power due to their infrared source. Furthermore, their accuracy is known to be greatly affected by the surrounding environmental conditions. Conventional hot-wire semiconductor sensors rely on the attachment and removal of oxygen, and therefore have the drawback of low detection sensitivity for fluorocarbon gases, which are relatively stable gases. In addition, because they use a heat source, there are safety concerns regarding their use with slightly flammable fluorocarbon gases.

[0006] The purpose of this disclosure is to provide a fluorocarbon gas sensor that is compact, consumes little power, and can safely detect fluorocarbon gases. [Means for solving the problem]

[0007] <1> Polymers whose capacitance changes in the presence of fluorocarbon gases, A detection unit for detecting potential changes based on the capacitance change, A fluorocarbon gas sensor having the following features. <2> The polymer has an aromatic ring in its main chain. <1> The fluorocarbon gas sensor described above. <3> The polymer having an imino group and an aromatic ring in its main chain <2> The fluorocarbon gas sensor described above. <4> The dielectric constant of the polymer is 5.0 or more. <2> or <3> The fluorocarbon gas sensor described above. <5> The polymer having repeating units represented by the following general formula (1) <2> from <4> A fluorocarbon gas sensor as described in any one of the items.

[0008] [ka] In the general formula (1) above, A is an aromatic ring, Y is a single bond, or one or more divalent groups selected from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents having 1 to 20 carbon atoms, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer. <6> In the above general formula (1), A is a benzene ring and Y is a divalent group containing one or more -NR'-. <5> The fluorocarbon gas sensor described above. <7> The polymer has repeating units represented by a general formula selected from the group consisting of the following. <2> The fluorocarbon gas sensor described above.

[0009] [ka] In the above general formula, n is an integer. <8> The polymer has a methyl group in its side chain, The methylation rate of the side chains of the polymer is 20% or more. <1> The fluorocarbon gas sensor described above. <9> The dielectric constant of the polymer is 3.5 or less. <8> The fluorocarbon gas sensor described above. <10> The polymer having repeating units represented by the following general formula (2) <8> or <9> The fluorocarbon gas sensor described above.

[0010] [ka] In the general formula (2) above, l is an integer between 0 and 10,000, m is an integer between 0 and 10,000, l+m is an integer greater than or equal to 10,000, and Z is -R or -X-(R) n Here, X is an (n+1) valent linking group, n is 1, 2, or 3, and R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents. <11> In the general formula (2), Z is -X-(R) n And, X is each independently an (n + 1)-valent linking group selected from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, and a hydrocarbon group which may have a substituent having 1 to 20 carbon atoms. R is each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. The fluorocarbon gas sensor according to <10>, wherein R' is each independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. <12> The fluorocarbon gas sensor according to <8>, wherein the polymer has a repeating unit represented by a general formula selected from the group consisting of the following.

[0011]

Chemical formula

[0012] [ka] In the general formula (1) above, A is an aromatic ring, Y is a single bond, or one or more divalent groups selected from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents having 1 to 20 carbon atoms, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer.

[0013] [ka] In the general formula (2) above, l is an integer between 0 and 10,000, m is an integer between 0 and 10,000, l+m is an integer greater than or equal to 10,000, and Z is -R or -X-(R) n Here, X is an (n+1) valent linking group, n is 1, 2, or 3, and R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents. <18> The repeating unit having a general formula selected from the group consisting of the following <17> Polymer for fluorocarbon gas sensors as described above.

[0014] [ka]

[0015] [ka] In the above general formula, n is an integer. [Effects of the Invention]

[0016] According to this disclosure, it is possible to provide a fluorocarbon gas sensor that is small, consumes little power, and can safely detect fluorocarbon gases. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a cross-sectional view of an example of a field-effect transistor, which is one embodiment of the fluorocarbon gas sensor of this embodiment. [Figure 2] Figure 2 is a graph showing the potential change on the polymer layer surface in the presence of fluorocarbon gas for the fluorocarbon gas sensors of Examples 1-6 and Comparative Examples 1-2. [Figure 3] Figure 3 is a graph showing the relationship between the fluorocarbon gas concentration and the potential change on the polymer layer surface for the fluorocarbon gas sensor of Example 1. [Figure 4] Figure 4 is a graph showing the change in potential over time at the polymer layer surface during the initial introduction and subsequent reintroduction of fluorocarbon gas in the fluorocarbon gas sensor of Example 1. [Figure 5] Figure 5 is a graph showing the potential change on the polymer layer surface after defluorocarbon gas treatment for the fluorocarbon gas sensor of Example 1. [Figure 6] Figure 6 is a graph showing the potential change on the surface of the polymer layer in the presence of fluorocarbon gas for the fluorocarbon gas sensor system of the example. [Modes for carrying out the invention]

[0018] (Fluorocarbon gas sensor) The fluorocarbon gas sensor of this disclosure comprises a polymer whose capacitance changes in the presence of a fluorocarbon gas, and a detection unit that detects a change in potential based on the change in capacitance.

[0019] Searching for a substance capable of detecting fluorocarbon gases, which have low polarization and low reactivity, is difficult. The fluorocarbon gas sensor of this disclosure is based on the inventors' discovery of a polymer whose capacitance changes in the presence of fluorocarbon gas. The inventors have found that a fluorocarbon gas sensor having a polymer whose capacitance changes in the presence of fluorocarbon gas and a detection unit that detects the potential change based on the capacitance change is small, consumes little power, and can safely detect fluorocarbon gas, thus completing the present invention. The fluorocarbon gas sensor of this disclosure is superior to conventional sensors in terms of cost, safety, and power consumption because it can detect fluorocarbon gases without using a heat source or infrared source. Furthermore, because it is smaller and consumes less power than conventional sensors, it can relatively minimize the impact on batteries in patrol machines such as drones and robots, which are expected to become widespread in the future.

[0020] There are no particular restrictions on the fluorocarbon gas to be detected by the aforementioned fluorocarbon gas sensor, and it can be appropriately selected depending on the purpose. Examples include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs). Mixtures of these may also be used.

[0021] Examples of the chlorofluorocarbons (CFCs) include dichlorodifluoromethane (R12) and trichlorofluoromethane (R11).

[0022] Examples of the aforementioned hydrochlorofluorocarbons (HCFCs) include chlorodifluoromethane (refrigerant number: R22), dichlorotrifluoroethane (refrigerant number: R123), and 2-chloro-1,1,1,2-tetrafluoroethane (refrigerant number: R124).

[0023] Examples of the aforementioned hydrofluorocarbons (HFCs) include trifluoromethane (refrigerant code: R23), difluoromethane (refrigerant code: R32), pentafluoroethane (refrigerant code: R125), 1,1,1-trifluoroethane (refrigerant code: R143a), 1,1,1,2-tetrafluoroethane (refrigerant code: R134a), and 1,1-difluoroethane (refrigerant code: R152a).

[0024] Examples of the aforementioned hydrofluoroolefins (HFOs) include 2,3,3,3-tetrafluoro-1-propene (refrigerant number: R1234yf), 1,3,3,3-tetrafluoropropene (refrigerant number: R1234ze), trans-1,2-difluoroethylene (refrigerant number: HFO1132(E)), and trifluoroethylene (refrigerant number: HFO1123).

[0025] The aforementioned mixture is, for example, a pseudo-azeotropic refrigerant mixture (refrigerant number: 140A) consisting of two components, R32 and R125, which was developed as a substitute refrigerant for R22. The refrigerant numbers in parentheses are the refrigerant numbers (ASHRAE numbers) specified in ISO 817:2014 by the International Organization for Standardization (ISO).

[0026] Among the aforementioned fluorocarbon gases, chlorodifluoromethane (refrigerant number: R22) is preferred in one embodiment, and difluoromethane (refrigerant number: R32) is preferred in another embodiment, and both may be detected.

[0027] <polymer> The polymer is not particularly limited as long as it is a polymer whose capacitance changes in the presence of a fluorocarbon gas, and can be appropriately selected according to the purpose. Examples include polymers having aromatic rings in the main chain and polymers having methyl groups in the side chains. In one embodiment, the polymer does not contain a dopant.

[0028] <<Polymers having aromatic rings in the main chain>> The polymer having aromatic rings in its main chain is a polymer with a relatively high dielectric constant, and it is preferable that the polymer has imino groups and aromatic rings in its main chain. The relative dielectric constant of the polymer is preferably 5.0 or higher. The lower limit of the relative dielectric constant is not limited, but for example, 10 5 The following applies:

[0029] The polymer having an aromatic ring in its main chain is, for example, a polymer having repeating units represented by the following general formula (1). The polymer may contain other repeating units, but it is preferable that it contains 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of the repeating units.

[0030] [ka] In the general formula (1) above, A is an aromatic ring, Y is a single bond, or one or more divalent groups selected from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents having 1 to 20 carbon atoms, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer.

[0031] In the above general formula (1), A is preferably a benzene ring, and Y is preferably a divalent group containing one or more -NR'- groups, and more preferably Y is a divalent group containing one or more -NH- (imino groups).

[0032] The polymer having an aromatic ring in its main chain preferably has repeating units represented by a general formula selected from the group consisting of the following, and these repeating units may be present as one type or as two or more types.

[0033] [ka] In the above general formula, n is an integer.

[0034] <<Polymers having methyl groups in their side chains>> The polymer having methyl groups in its side chains is a polymer with a relatively low dielectric constant. The relative dielectric constant of the polymer is preferably 3.5 or less. The upper limit of the relative dielectric constant is not limited, but for example, it is 2 or more.

[0035] The methylation rate of the side chains of the polymer is preferably 20% or more, more preferably 30% or more, and even more preferably 40% or more. Here, the methylation rate refers to the ratio (%) of the molecular weight of the methyl group to the total molecular weight of the polymer.

[0036] The polymer having methyl groups in its side chains is, for example, a polymer having repeating units represented by the following general formula (2). The polymer may contain other repeating units, but it is preferable that it contains 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, or 90 mol% or more of the repeating units.

[0037] [ka] In the general formula (2) above, l is an integer between 0 and 10,000, m is an integer between 0 and 10,000, l+m is an integer greater than or equal to 10,000, and Z is -R or -X-(R) n Here, X is an (n+1) valent linking group, n is 1, 2, or 3, and R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents.

[0038] In the general formula (2), Z is -X-(R) n And, Each X is an independently selected (n+1) valency linking group from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents from 1 to 20 carbon atoms. Each R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents. Each R' is preferably independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.

[0039] The polymer having a methyl group in its side chain preferably has repeating units represented by a general formula selected from the group consisting of the following, and these repeating units may be present individually or in combination of two or more types.

[0040] [ka] In the above general formula, n is an integer.

[0041] [Method for identifying polymers] There are no particular limitations on the method for identifying the polymer, and it can be appropriately selected depending on the purpose. For example, one method is to analyze the polymer using the infrared total reflection attenuation method (IR-ATR method) with a Fourier transform infrared spectrometer (FT-IR) to identify the polymer's constituent components. FT-IR measurements can be performed, for example, using a Nicolet 6700 (manufactured by Thermo Fisher Scientific Co., Ltd.).

[0042] <Detection Unit> The detection unit is not particularly limited as long as it can detect the potential change based on the capacitance change of the polymer in the presence of a Freon gas, and any known detection unit can be appropriately selected depending on the purpose. Examples of sensors having such a detection unit include field-effect transistor (FET) sensors, metal-oxide-semiconductor field-effect transistor (MOSFET) sensors, metal-oxide-semiconductor sensors, quartz crystal oscillator (QCM) sensors, and surface acoustic wave (SAW) sensors.

[0043] [Modes of field-effect transistors] In one embodiment, the fluorocarbon gas sensor is preferably a field-effect transistor having a gate insulating layer, a source layer, and a drain layer. The field-effect transistor has the polymer on the gate insulating layer.

[0044] Figure 1 shows a cross-sectional view of an example of a field-effect transistor, which is one embodiment of the fluorocarbon gas sensor of this embodiment. The field-effect transistor 10 shown in Figure 1 has a semiconductor substrate 1, a source layer S and a drain layer D on the semiconductor substrate 1, a gate insulating layer G on the source layer S and drain layer D, and a polymer layer 2 as a gas-sensitive film on the gate insulating layer G. A channel is formed between the source layer S and the drain layer D.

[0045] Polymer layer 2 contains the polymer (polymer for fluorocarbon gas sensors). When exposed, polymer layer 2 can interact with fluorocarbon gas contained in the gas phase and functions as a gas-sensitive film that undergoes capacitance change in the presence of fluorocarbon gas. Because fluorocarbon gas has low reactivity, a reaction with the gas-sensitive film cannot be expected. However, the presence of fluorocarbon gas can be detected by detecting a change in potential (ΔV=Q / ΔC) based on a change in capacitance (ΔC) due to adsorption to the surface of the gas-sensitive film or penetration into the interior. On the other hand, when detecting acidic gases such as acetic acid (CH3COOH) or hydrochloric acid (HCl), the presence of acidic gas can be detected by detecting a change in potential (ΔV=ΔQ / C) based on a change in charge (ΔQ) due to a small change in pH etc. caused by reaction with the gas-sensitive film.

[0046] As the semiconductor substrate 1, for example, Si or silicon carbide (SiC) can be used. As the gate insulating layer G, for example, a two-layer structure in which a Si3N4 insulating layer is provided on an SiO2 layer can be used. Furthermore, as the gate electrode (reference electrode) (not shown), for example, an Ag / AgCl electrode can be used.

[0047] There are no particular restrictions on the method for forming the polymer layer 2, and it can be appropriately selected depending on the purpose. For example, one method is to coat with a polymer solution dissolved in a solvent and then remove the solvent. Examples of coating methods include spin coating, bar coating, and spray coating.

[0048] There are no particular restrictions on the average thickness of the polymer layer 2, and it can be appropriately selected according to various conditions such as the sensitivity to the target fluorocarbon gas. However, a thickness of 50 nm to 500 nm is preferred, and a thickness of 100 nm to 250 nm is more preferred.

[0049] The aforementioned solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include water, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylisobutylamide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, γ-butyrolactone, ethyl lactate, 1,3-dimethyl-2-imidazolidinone, N,N'-dimethylpropylene urea, 1,1,3,3-tetramethylurea, dimethyl sulfoxide (DMSO), sulfolane, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol ethyl methyl ether, and diethylene glycol dimethyl ether.

[0050] These may be used individually or in combination of two or more types.

[0051] There are no particular restrictions on the polymer content in the polymer solution, and it can be appropriately selected according to various conditions such as sensitivity to the target fluorocarbon gas. However, a content of 0.01 mg / mL to 10 mg / mL is preferred, and 0.1 mg / mL to 5 mg / mL is more preferred.

[0052] (Fluorocarbon gas sensor system) The fluorocarbon gas sensor system of the present disclosure comprises a plurality of fluorocarbon gas sensors of the present disclosure, wherein the plurality of fluorocarbon gas sensors comprises a first fluorocarbon gas sensor having a first polymer as the polymer, and a second fluorocarbon gas sensor having a second polymer as the polymer. Furthermore, there may be an nth fluorocarbon gas sensor having an nth polymer (where n is any integer greater than or equal to 3).

[0053] Furthermore, the fluorocarbon gas sensor system may have multiple fluorocarbon gas sensors in which the polymer concentration and polymer layer thickness differ from one another, thereby enabling a fluorocarbon gas sensor system with different responses to fluorocarbon gases of various concentrations.

[0054] In one embodiment, the fluorocarbon gas sensor system is preferably a system having a plurality of field-effect transistors, and more preferably a system having a plurality of multi-channel transistors arranged in an array.

[0055] In one embodiment, the fluorocarbon gas sensor system is preferably a complementary metal-oxide-semiconductor (CMOS). The complementary metal-oxide-semiconductor (CMOS) is a fluorocarbon gas sensor which is a p-type metal-oxide-semiconductor field-effect transistor (pMOSFET), The system includes a fluorocarbon gas sensor, which is an n-type metal-oxide-semiconductor field-effect transistor (nMOSFET). By using a fluorocarbon gas sensor system that integrates multiple transistors in this way, it is possible to measure multiple types of fluorocarbon gases simultaneously.

[0056] (Polymer for fluorocarbon gas sensors) The polymer for fluorocarbon gas sensors disclosed herein is a polymer that can be used in applications for fluorocarbon gas sensors and is a polymer whose capacitance changes in the presence of fluorocarbon gas.

[0057] The polymer for the fluorocarbon gas sensor is selected from the group consisting of polymers having an aromatic ring with repeating units represented by the following general formula (1), and polymers having methyl groups in the side chains with repeating units represented by the following general formula (2). These may be used individually or in combination of two or more.

[0058] [ka] In the general formula (1) above, A is an aromatic ring, Y is a single bond, or one or more divalent groups selected from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents having 1 to 20 carbon atoms, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer.

[0059] In the above general formula (1), A is preferably a benzene ring, and Y is preferably a divalent group containing one or more -NR'- groups, and more preferably Y is a divalent group containing one or more -NH- (imino groups).

[0060] [ka] In the general formula (2) above, l is an integer between 0 and 10,000, m is an integer between 0 and 10,000, l+m is an integer greater than or equal to 10,000, and Z is -R or -X-(R) n Here, X is an (n+1) valent linking group, n is 1, 2, or 3, and R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents.

[0061] In the general formula (2), Z is -X-(R) n And, Each X is an independently selected (n+1) valency linking group from the group consisting of -O-, -C(=O)-, -S(=O)2-, -NR'-, -C(OR')R'-, and -C(OR')(-)2, which may have substituents from 1 to 20 carbon atoms. Each R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents. Each R' is preferably independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.

[0062] The polymer for the fluorocarbon gas sensor is preferably a polymer having repeating units represented by a general formula selected from the group consisting of the following.

[0063] [ka]

[0064] [ka] In the above general formula, n is an integer.

[0065] Examples of polymers for fluorocarbon gas sensors include polymers having aromatic rings in their main chain, such as polyaniline having repeating unit A1, poly(m-aminophenylboronic acid) having repeating unit A2, and polyurethane having repeating unit U; and polymers having methyl groups in their side chains, such as polyisobutylene having repeating unit I, polybutyl methacrylate having repeating unit B, polydimethylsiloxane having repeating unit D, and polydiethylsiloxane having repeating unit E. The polymers for fluorocarbon gas sensors may have one of these repeating units alone or two or more. Furthermore, the polymers for fluorocarbon gas sensors may be used alone or two or more in combination.

[0066] Polyaniline having repeating unit A1, poly(m-aminophenylboronic acid) having repeating unit A2, and polyurethane having repeating unit U can each respond to both chlorodifluoromethane (R22) and difluoromethane (R32), while polyisobutylene having repeating unit I, polybutyl methacrylate having repeating unit B, polydimethylsiloxane having repeating unit D, and polydiethylsiloxane having repeating unit E can each respond to chlorodifluoromethane (R22).

[0067] As will be clear from the examples described later, these polymers exhibit a decrease in capacitance C and an increase in potential V in the presence of a Freon gas (ΔV = Q / ΔC). The response to the Freon gas can be detected by the potential change (increase) based on the capacitance change (decrease). In other embodiments, the capacitance C may increase and the potential V may decrease in the presence of a Freon gas, and the response to the Freon gas may be detected by the potential change (decrease) based on the capacitance change (increase). [Examples]

[0068] The present invention will be described more specifically below based on examples, but the present invention is not limited to the following examples.

[0069] <Preparation of polymers and polymer solutions for fluorocarbon gas sensors> Each of the following six polymers or polymer mixtures was dissolved in dimethyl sulfoxide (DMSO) as a solvent to a concentration of 1 mg / mL to prepare a polymer solution.

[0070] Six types of polymers or polymer mixtures were used: a 1:1 (mass ratio) mixture (A) of polyaniline having repeating unit A1 and poly(m-aminophenylboronic acid) having repeating unit A2; polyurethane having repeating unit U (U); polyisobutylene having repeating unit I (I); polybutyl methacrylate having repeating unit B (B); polydimethylsiloxane having repeating unit D (D); and polydiethylsiloxane having repeating unit E (E).

[0071] [ka]

[0072] [ka]

[0073] (Example 1) <Preparation of the detection unit> A field-effect transistor 10, as shown in Figure 1, was prepared. The field-effect transistor 10 has a two-layer structure in which a Si substrate is provided as the semiconductor substrate 1, and a Si3N4 insulating layer is provided on an SiO2 layer as the gate insulating layer G.

[0074] <Manufacturing of field-effect transistor type fluorocarbon gas sensors> A polymer solution of polydimethylsiloxane (D) (1 mg / mL) was applied to the gate insulating layer G by spin coating at 3,000 rpm. After spin coating, the material was stored overnight in a vacuum desiccator to remove the solvent, forming a polymer layer 2 on the gate insulating layer G. Thus, a field-effect transistor type fluorocarbon gas sensor of Example 1, having a polymer layer 2 on the gate insulating layer G, was manufactured.

[0075] Observation of the formed polymer layer 2 using an atomic force microscope (AFM, model number: 920-006-101, Veeco Metrology) revealed that the average thickness of polymer layer 2 was approximately 100 nm.

[0076] (Examples 2-6) Except for the fact that, in Example 1, a 1:1 (mass ratio) mixture of polyaniline and poly(m-aminophenylboronic acid) (A), polyurethane (U), polyisobutylene (I), polybutyl methacrylate (B), or polydiethylsiloxane (E) was used as the polymer instead of polydimethylsiloxane (D) in Example 1, the field-effect transistor type fluorocarbon gas sensors of Examples 2 to 6 were manufactured in the same manner as in Example 1.

[0077] (Comparative Example 1) A field-effect transistor type fluorocarbon gas sensor of Comparative Example 1 was manufactured in the same manner as in Example 1, except that a polymer was not applied to the gate insulating layer G.

[0078] (Comparative Example 2) In Comparative Example 2, a fluorocarbon gas sensor of a field effect transistor type was manufactured in the same manner as in Example 1, except that polystyrene (T) shown below was used instead of polydimethylsiloxane (D) as the polymer.

[0079] [Chemical formula]

[0080] Each field effect transistor type fluorocarbon gas sensor (number of test samples: 79 or 80) was connected to a measuring instrument and placed in a chamber provided with a gas flow path. The gas flow rate was controlled to 100 mL / min, and 10 5 ppm of chlorodifluoromethane (refrigerant number: R22) or difluoromethane (refrigerant number: R32) was introduced into the chamber under an air atmosphere, and the potential change from the start of gas introduction until 5 minutes had elapsed was measured. The results are shown in FIG. 2. FIG. 2 is a graph showing the potential change on the surface of the polymer layer in the presence of a fluorocarbon gas for the fluorocarbon gas sensors of Examples 1 to 6 and Comparative Examples 1 to 2.

[0081] From the results in FIG. 2, it was found that polydimethylsiloxane (D), poly(diethylsiloxane) (E), polyisobutylene (I), and poly(butyl methacrylate) (B) can detect chlorodifluoromethane (refrigerant number: R22). Also, it was found that a 1:1 (mass ratio) mixture (A) of polyaniline and poly(m-aminophenylboronic acid), and polyurethane (U) can detect both chlorodifluoromethane (refrigerant number: R22) and difluoromethane (refrigerant number: R32).

[0082] [Concentration dependence] Regarding the field effect transistor type fluorocarbon gas sensor of Example 1, in addition to 10 5 ppm of chlorodifluoromethane (refrigerant number: R22) shown in FIG. 2, 10 2 ppm, 10 3 ppm, 10 4 ppm, and 10 6Measurements were performed for 5 minutes with 80 test samples under ppm concentration conditions. The results are shown in Figure 3. Figure 3 is a graph showing the relationship between fluorocarbon gas concentration and the potential change on the polymer layer surface for the fluorocarbon gas sensor of Example 1.

[0083] The results in Figure 3 show that the electrical signal increases with increasing concentration of chlorodifluoromethane (refrigerant number: R22), and therefore, a change in the potential on the polymer layer surface is observed in a concentration-dependent manner of the chlorofluoromethane gas. Furthermore, since the change in the potential on the polymer layer surface changes positively in a concentration-dependent manner of chlorodifluoromethane (refrigerant number: R22), it was found that the concentration of the chlorofluoromethane gas can be measured.

[0084] <Reusable> <<Consideration of initialization by nitrogen purging>> In the field-effect transistor type fluorocarbon gas sensor of Example 1, chlorodifluoromethane (refrigerant number: R22) was introduced, and after 5 minutes, the ambient atmosphere was replaced with nitrogen gas. After 200 seconds following the nitrogen gas replacement, chlorodifluoromethane (refrigerant number: R22) was introduced again. The results are shown in Figure 4. Figure 4 is a graph showing the change in potential at the polymer layer surface during the initial introduction and reintroduction of fluorocarbon gas in the fluorocarbon gas sensor of Example 1. The vertical axis represents the potential at the polymer layer surface relative to the reference electrode.

[0085] As shown in Figure 4, a clear potential response was observed when the fluorocarbon gas was first introduced. However, after nitrogen purging, the potential did not return to its initial value, and no potential response was observed when the fluorocarbon gas was reintroduced. From this, it is inferred that the fluorocarbon gas penetrated and adsorbed into the polymer layer in the presence of the fluorocarbon gas, and that nitrogen purging did not remove the fluorocarbon gas from within the polymer, thus preventing the polymer layer from being reset.

[0086] <<Consideration of CFC-free gas removal treatment>> For the field-effect transistor type fluorocarbon gas sensor of Example 1 (number of test samples: 80), in order to explore and evaluate the conditions for repeatedly using the fluorocarbon gas sensor after removing the chlorodifluoromethane (refrigerant number: R22) adsorbed in the first measurement, the fluorocarbon gas sensor after the first measurement was placed in a vacuum oven and subjected to a defluorocarbon gas treatment at 60°C for 1 hour. Subsequently, a second measurement was performed in the same manner as the first measurement (number of test samples: 80).

[0087] Furthermore, the fluorocarbon gas sensors used in the second measurement were placed in a vacuum desiccator and stored for 5 hours to remove the fluorocarbon gas. Subsequently, the third measurement was performed in the same manner as the first measurement (number of test samples: 80).

[0088] The results are shown in Figure 5. Figure 5 is a graph showing the potential change on the polymer layer surface after defluorocarbon gas treatment for the fluorocarbon gas sensor of Example 1. The labels on the horizontal axis, 1st to 3rd, indicate the measurement results for the 1st to 3rd trials, respectively.

[0089] The results shown in Figure 5 confirm that a potential response is observed when fluorocarbon gas is reintroduced by vacuum heating or placing the polymer in a vacuum as a fluorocarbon gas removal treatment. This indicates that fluorocarbon gas that has penetrated and adsorbed into the polymer can be removed under vacuum, and therefore the polymer layer can be initialized.

[0090] <Manufacturing of fluorocarbon gas sensor systems> A (4×4)×5 FET array sensor (manufactured by Hamamatsu Photonics K.K.) was used as the detection unit for the fluorocarbon gas sensor system. Each sensor in the (4×4)×5 FET array sensor corresponds to a field-effect transistor (FET) as shown in Figure 1. A (4×4) FET array is formed in a 200μm×200μm region on an 800μm×800μm substrate, and five of these arrays are linked together to form an FET array of approximately 800μm×4mm in size. A polymer layer of polydimethylsiloxane (D) or polyisobutylene (I) was formed according to the following procedure. Alternatively, no polymer layer was formed.

[0091] Specifically, a polymer solution of polydimethylsiloxane (D) was applied to the gate insulating layer of two (4x4)x5 FET arrays of a (4x4)x5 FET array sensor, and the solvent was removed to form a polymer layer. Similarly, a polymer solution of polyisobutylene (I) was applied to the gate insulating layer of two (4x4)x2 FET arrays, and the solvent was removed to form a polymer layer. As a control, a comparative fluorocarbon gas sensor portion without a polymer layer was fabricated by not applying a polymer solution to the gate insulating layer of the (4x4) array FETs. Through these steps, a fluorocarbon gas sensor system with multiple fluorocarbon gas sensors was manufactured.

[0092] The manufactured fluorocarbon gas sensor system was subjected to the same procedure as in Example 1. 5 Chlorodifluoromethane (refrigerant number: R22) was introduced at a concentration of ppm, and the potential change on the polymer layer surface was measured. The results are shown in Figure 6. Figure 6 is a graph showing the potential change on the polymer layer surface in the presence of fluorocarbon gas for the fluorocarbon gas sensor system of the example. Gas introduction was started at 200 seconds on the horizontal axis, and the potential change was measured for 500 seconds (i.e., from the start of gas introduction until 5 minutes had elapsed). As a result, it was possible to observe the potential change on the polymer layer surface in response to the introduction of fluorocarbon gas using a small and low-power fluorocarbon gas sensor system.

[0093] From the above, it has been found that the fluorocarbon gas sensor and fluorocarbon gas sensor system of this disclosure are small, have low power consumption, and can safely detect fluorocarbon gases. Furthermore, it has been found that the polymer for fluorocarbon gas sensors of this disclosure is suitable for applications of fluorocarbon gas sensors and fluorocarbon gas sensor systems that are small, have low power consumption, and can safely detect fluorocarbon gases.

[0094] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Explanation of Symbols]

[0095] 1. Semiconductor substrate 2 Polymer layer S Source Layer D drain layer G gate insulating layer 10. Field-effect transistor (fluorocarbon gas sensor)

Claims

1. Polymers whose capacitance changes in the presence of fluorocarbon gases, A detection unit for detecting potential changes based on the capacitance change, A fluorocarbon gas sensor having the following features.

2. The fluorocarbon gas sensor according to claim 1, wherein the polymer has an aromatic ring in its main chain.

3. The fluorocarbon gas sensor according to claim 2, wherein the polymer has an imino group and an aromatic ring in its main chain.

4. The fluorocarbon gas sensor according to claim 2, wherein the relative dielectric constant of the polymer is 5.0 or more.

5. The fluorocarbon gas sensor according to claim 2, wherein the polymer has repeating units represented by the following general formula (1). 【Chemistry 1】 In the general formula (1) above, A is an aromatic ring, and Y is a single bond, or -O-, -C(=O)-, -S(=O) ２ -, -NR'-, -C(OR')R'-, and -C(OR')(-) ２ R' is one or more divalent groups selected from the group consisting of hydrocarbon groups having 1 to 20 substituents, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer.

6. The fluorocarbon gas sensor according to claim 5, wherein in the general formula (1), A is a benzene ring and Y is a divalent group containing one or more -NR'-.

7. The fluorocarbon gas sensor according to claim 2, wherein the polymer has repeating units represented by a general formula selected from the group consisting of the following. 【Chemistry 2】 In the above general formula, n is an integer.

8. The polymer has a methyl group in its side chain, The fluorocarbon gas sensor according to claim 1, wherein the methylation rate of the side chains of the polymer is 20% or more.

9. The fluorocarbon gas sensor according to claim 8, wherein the relative dielectric constant of the polymer is 3.5 or less.

10. The fluorocarbon gas sensor according to claim 8, wherein the polymer has repeating units represented by the following general formula (2). 【Transformation 3】 In the general formula (2) above, l is an integer between 0 and 10,000, m is an integer between 0 and 10,000, l + m is an integer of 10,000 or more, and Z is -R or -X-(R) ｎ Here, X is an (n+1) valent linking group, n is 1, 2, or 3, and R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents.

11. In the general formula (2), Z is -X-(R) ｎ And, X is independent of each other: -O-, -C(=O)-, -S(=O) ２ -, -NR'-, -C(OR')R'-, and -C(OR')(-) ２ , a (n+1) valent linking group selected from the group consisting of hydrocarbon groups which may have substituents from 1 to 20 carbon atoms, Each R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms, which may have substituents. The fluorocarbon gas sensor according to claim 10, wherein R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms.

12. The fluorocarbon gas sensor according to claim 8, wherein the polymer has repeating units represented by a general formula selected from the group consisting of the following. 【Chemistry 4】 In the above general formula, n is an integer.

13. c having a gate insulating layer, a source layer, and a drain layer, The fluorocarbon gas sensor according to claim 1, further comprising the polymer on the gate insulating layer.

14. The fluorocarbon gas sensor according to claim 1, wherein the fluorocarbon gas is selected from the group consisting of chlorodifluoromethane and difluoromethane.

15. Having a plurality of fluorocarbon gas sensors as described in claim 1, Multiple of the above-mentioned fluorocarbon gas sensors, A first fluorocarbon gas sensor having a first polymer as the polymer, A fluorocarbon gas sensor system comprising a second fluorocarbon gas sensor having a second polymer as the aforementioned polymer.

16. A p-type metal oxide film semiconductor field-effect transistor is used as a fluorocarbon gas sensor, A fluorocarbon gas sensor, which is an n-type metal oxide film semiconductor field-effect transistor, The fluorocarbon gas sensor system according to claim 15, which is a complementary metal oxide film semiconductor having

17. A polymer for fluorocarbon gas sensors selected from the group consisting of polymers having repeating units represented by the following general formula (1) and polymers having repeating units represented by the following general formula (2). 【Transformation 5】 In the general formula (1) above, A is an aromatic ring, and Y is a single bond, or -O-, -C(=O)-, -S(=O) ２ -, -NR'-, -C(OR')R'-, and -C(OR')(-) ２ R' is one or more divalent groups selected from the group consisting of hydrocarbon groups having 1 to 20 substituents, R' is independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and n is an integer. 【Transformation 6】 In the general formula (2), l is an integer of 0 or more and less than 10,000, m is an integer of 0 or more and less than 10,000, l + m is an integer of 10,000 or more, and Z is -R or -X-(R). ｎ X is a (n + 1)-valent linking group, n is 1, 2, or 3, and each R is independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms which may have a substituent.

18. A polymer for fluorocarbon gas sensors having repeating units represented by a general formula selected from the group consisting of the following. 【Transformation 7】 【Transformation 8】 In the above general formula, n is an integer.

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