Device, concentration measurement device comprising same, and concentration measurement method using same

Abstract

[Problem] To provide a device capable of obtaining a potential response related to a gas concentration change by adjusting the concentration of an ionophore, which is a component related to ion acquisition within a sensitive membrane component, and the concentration of an anion excluder and / or a cation excluder, while also being capable of prolonging the life of a potential response related to a gas. Specifically, to provide a device capable of achieving potential responsivity and life prolongation, and of being used in a concentration measurement device and a concentration measurement method. [Solution] A device comprising an insulating substrate, at least one insulating composite layer, and a storage part that is capable of storing a subject, wherein: the insulating composite layer has a pair of electrodes and a semiconductor layer that is in contact with the pair of electrodes; the storage part has an ionization part that ionizes a detection target within the subject; an ion acquisition part is provided between the insulating composite layer and the storage part, and includes an ionophore that acquires the ionized detection target, and an anion excluder and / or a cation excluder; the weight fraction (X) of the anion excluder and / or the cation excluder is greater than 0.0 wt% but not greater than 4.0 wt%; the weight fraction (Y) of the ionophore is 2.0-8.0 wt% inclusive; and X+Y is 4.0-12.0 wt% inclusive.

Description

Device, concentration measuring apparatus including same, and concentration measuring method using same

[0001] The present invention relates to the magnitude of current flowing between a pair of electrodes according to the concentration of a detection target in an analyte, and the threshold voltage V, which is the voltage value of a third electrode when switching whether a current flows between the pair of electrodes th for a device in which changes, more specifically, the magnitude of such current and the threshold voltage V th relate to a concentration measuring apparatus and a concentration measuring method for measuring the concentration of a detection target in an analyte based on the change of

[0002] In the upcoming super-smart society, Society 5.0, the goal is to achieve both economic development and solutions to social issues, and IoT, which underpins this, requires sensors for data acquisition.

[0003] Conventionally, electrochemical sensors using semiconductors are known as methods for detecting the presence, absence and concentration of specific components in gas. A conventional gas sensor 200 has, for example, as shown in FIG. 11, a configuration including a pair of electrodes 241, 242 on an insulating substrate 212, and a semiconductor layer 244 in contact with the pair of electrodes 241, 242. In such a gas sensor 200, when in contact with the analyte gas, the detection target in the analyte is adsorbed onto the semiconductor layer 244, and the resistance value of the semiconductor layer 244 changes. By measuring the change in the resistance value of the semiconductor layer 244, the presence, absence and concentration of the detection target in the analyte can be detected.

[0004] As a sensitive membrane of such a gas sensor 200, one using a plasticized resin ion-sensitive membrane containing an ionophore is used for detection and concentration measurement of specific ions present in a solution.

[0005] Non-Patent Document 1 discloses an example for the purpose of detecting ions in a solution, where the ionophore concentration in the ion-sensitive membrane is set to 1% by weight, and the contents of the plasticizer and the anion exclusion agent are adjusted to achieve both suppression of component precipitation and the magnitude of potential response.

[0006] Elsayed M. Zahran, Andrea New, Vasilis Gavalas, Leonidas G. Bachas, “Polymeric plasticizer extends the lifetime of PVC-membrane ion-selective electrodes”, Analyst, Vol. 139, No. 4, pp. 757-763 (2014). DOI: 10.1039 / C3AN01963B.

[0007] However, based on the description in Non-Patent Document 1, when a sensitive film with an ionophore concentration of 2% by weight is used in a gas sensor that ionizes a gas, accumulates those ions, and measures its concentration, the inventors' investigations revealed that under conditions of continuous gas supply, the potential response saturates relatively quickly, resulting in a problem where it cannot track changes in gas concentration over a long period of time. Such a gas sensor continuously or intermittently collects and measures the target gas, but if the potential response to the gas that has been collected, ionized, and accumulated ions saturates quickly, the sensor becomes unusable at that point, and the device's lifespan ends. In other words, a longer saturation time for the potential response means a longer lifespan for the potential response.

[0008] In view of the current situation, the present invention aims to provide a device that can be used in a concentration measuring apparatus and concentration measuring method that can obtain a potential response to changes in gas concentration and extend the lifetime of the potential response to gas by adjusting the concentrations of ionophores, which are components of the sensitive film that are related to ion trapping, and anion eliminators and / or cation eliminators, thereby achieving both potential responsiveness and extended lifetime.

[0009] The present invention was made to solve the problems of the prior art described above, and the device of the present invention, the concentration measuring apparatus equipped therewith, and the concentration measuring method using the same include those configured as follows.

[0010] [1] A device comprising an insulating substrate, at least one insulating composite layer, and a storage section capable of storing a sample, wherein the insulating composite layer comprises a pair of electrodes and a semiconductor layer in contact with the pair of electrodes, the storage section comprises an ionization section for ionizing a target to be detected in the sample, and between the insulating composite layer and the storage section comprises an ion capture section containing an ionophore for capturing the ionized target to be detected and an anion eliminator and / or a cation eliminator, wherein the weight fraction (X) of the anion eliminator and / or cation eliminator is greater than 0.0% by weight and 4.0% by weight or less, the weight fraction (Y) of the ionophore is 2.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less.

[0011] [2] The device according to [1], wherein X is 0.1% by weight or more and 4.0% by weight or less.

[0012] [3] The device according to [1], wherein Y is 2.5% by weight or more and 8.0% by weight or less.

[0013] [4] The device according to [1], wherein X is 0.1% by weight or more and 4.0% by weight or less, and Y is 2.5% by weight or more and 8.0% by weight or less.

[0014] [5] The device according to any one of [1] to [4], wherein the semiconductor layer is composed of an oxide containing indium (In), zinc (Zn), and an additive element (M), and the additive element (M) includes at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).

[0015] [6] The device according to any one of [1] to [5], wherein the ionization portion includes a gas permeable membrane.

[0016] [7] The device according to any one of [1] to [6], wherein the ionization portion is gel-like.

[0017] [8] The device according to any one of [1] to [7], wherein the ionization portion is a solid electrolyte having an electrode catalyst.

[0018] [9] The device according to any one of [1] to [8], wherein the ionization portion is a liquid and further comprises a third electrode in contact with the liquid.

[0019]

[10] The device according to any one of [1] to [9], further comprising a third electrode formed on the insulating substrate in an insulated state from the insulating composite layer.

[0020]

[11] The field effect mobility of the semiconductor layer is 20 cm 2 A device according to any of [1] to

[10] , wherein the value is greater than or equal to / Vs.

[0021]

[12] The OFF current between the pair of electrodes of the semiconductor layer is 1 × 10 -12 A device that is A or less, as described in any of [1] to

[11] .

[0022]

[13] A concentration measuring device comprising a device described in any of [1] to

[12] and a control device, wherein the control device includes a voltage applying means for applying a voltage between the pair of electrodes, a current measuring means for measuring the current flowing between the pair of electrodes when a voltage is applied by the voltage applying means, and a concentration calculating means for calculating the concentration of the object to be detected in the subject based on the inter-electrode current measured by the current measuring means.

[0023]

[14] A device as described in [9] or

[10] , and a control device, the control device comprising: a voltage applying means for varying the voltage applied between the electrode into which current flows and the third electrode of the pair of electrodes; a current measuring means for measuring the current flowing between the pair of electrodes; and a threshold voltage V, which is the voltage value of the third electrode when it switches whether or not current flows between the pair of electrodes, based on the voltage value applied by the voltage applying means and the current value measured by the current measuring means. th A threshold voltage detection means for detecting the threshold voltage V detected by the threshold voltage detection means th A concentration measuring device comprising a concentration calculation means for calculating the concentration of a target to be detected in the subject based on the above.

[0024]

[15] A concentration measurement method for detecting the concentration of a target to be detected in a test subject using the device according to any one of [1] to

[12] , the method comprising: measuring an interelectrode current which is a current value flowing between the pair of electrodes when a voltage is applied between the pair of electrodes, and measuring the concentration of the target to be detected in the test subject based on the interelectrode current.

[0025]

[16] A concentration measurement method for detecting the concentration of a target to be detected in a test subject using the device according to [9] or

[10] , the method comprising: a threshold voltage V which is a voltage value of the third electrode when whether a current flows between the pair of electrodes is switched th is detected, and the threshold voltage V th A concentration measurement method, comprising measuring the concentration of the target to be detected in the test subject based on .

[0026] According to the present invention, by controlling the weight fraction of the total weight of the ionophore and the anion excluding agent and / or cation excluding agent in the ion trapping part to a specific range suitable for gas sensor applications, a potential response to a change in gas concentration can be obtained, and saturation of the potential response is less likely to occur even under conditions of continuous gas supply, so that the response to gas concentration can be maintained for a long time. That is, both potential responsiveness and long service life can be achieved. Therefore, the service life of a gas sensor for detecting the concentration of a target to be detected in a test subject can be greatly improved.

[0027] FIG. 1 is a schematic diagram for explaining the configuration of the concentration measurement device according to the present embodiment. FIG. 2 is a schematic diagram for explaining the configuration of a device used in the concentration measurement device of FIG. 1. FIG. 3 is a schematic diagram showing a modified example of the device used in the concentration measurement device shown in FIG. 1. FIG. 4 is a schematic diagram for explaining the configuration of another embodiment of the concentration measurement device of the present invention. FIG. 5 is a schematic front view showing a modified example of the device used in the concentration measurement device shown in FIG. 4. FIG. 6 is a schematic side view of the device shown in FIG. 5. FIG. 7 is a graph showing the threshold voltage V with respect to the operating time of the device and the ammonia concentration thThe graphs show the changes in the threshold voltage V for sample 8, with Figure 7(a) showing the measurement results for sample 8 and Figure 7(b) showing the measurement results for sample 9. Figure 8 shows the relationship between the operating time of the device and the threshold voltage V for ammonia concentration for sample 7. th This graph shows the change in the threshold voltage V with respect to the operating time of the device and ammonia concentration. Figure 9 shows the threshold voltage V with respect to the operating time of the device and ammonia concentration. th The graphs show the changes in the threshold voltage V. Figure 9(a) shows the measurement results for sample 1, Figure 9(b) shows the measurement results for sample 2, and Figure 9(c) shows the measurement results for sample 3. Figure 10 shows the relationship between the operating time of the device and the threshold voltage V with respect to ammonia concentration. th The graphs show the changes, with Figure 10(a) showing the measurement results for sample 4, Figure 10(b) showing the measurement results for sample 5, and Figure 10(c) showing the measurement results for sample 6. Figure 11 is a schematic diagram illustrating the configuration of a conventional gas sensor.

[0028] Hereinafter, embodiments (examples) of the present invention will be described in more detail with reference to the drawings. Figure 1 is a schematic diagram illustrating the configuration of the concentration measuring device in this embodiment, and Figure 2 is a schematic diagram illustrating the configuration of the device used in the concentration measuring device of Figure 1.

[0029] In this embodiment, the "subject" is defined as any substance to be detected within the subject that is ionized; unless otherwise specified, its state is not limited and it may be a gas, liquid, or solid.

[0030] Furthermore, in this specification, the term "third electrode" includes both the reference electrode and the gate electrode.

[0031] As shown in Figure 1, the concentration measuring device 50 of this embodiment comprises a device 10 having an insulating substrate 12, at least one insulating composite layer 14, and a storage section 16 capable of storing a sample, and a control device 60.

[0032] Furthermore, the device 10 configured as shown in Figure 2 can also be a semiconductor element such as a field-effect transistor (FET) or a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0033] The insulating substrate 12 is a substrate made of an insulating material such as glass or ceramics.

[0034] The insulating composite layer 14 has a pair of electrodes (a first electrode 141 and a second electrode 142) and a semiconductor layer 144 that is in contact with the pair of electrodes 141 and 142.

[0035] The storage section 16 is not particularly limited as long as it is capable of storing the sample, but in this embodiment, as will be described later, the ionization section 17 provided in the storage section 16 is in contact with the ion capture section 18, and is configured by a partition section 16a that surrounds the ion capture section 18.

[0036] The storage section 16 contains an ionization section 17 that ionizes the target to be detected in the sample. The ionization section 17 is not particularly limited as long as it can ionize the target to be detected, and for example, a solvent such as water can be used. The solvent in the ionization section 17 may be used in liquid form, but by gelling it, leakage of the ionization section 17 from the storage section 16 is prevented, making it easier to handle the concentration measuring device 50. The ionization section 17 can also be a solid electrolyte having an electrode catalyst. With such a configuration, the target to be detected in the sample is ionized by the electrode catalyst, the solid electrolyte conducts only specific ions, and the ion capture section 18 can capture only the ions of the target to be detected.

[0037] Furthermore, an ion capture unit 18 is provided between the insulating composite layer 14 and the storage unit 16. The ion capture unit 18 is selective for the target to be detected in the sample. Specifically, it has the property of selectively capturing the target ions. As such an ion capture unit 18, for example, ionophores such as lithium ionophores, potassium ionophores, sodium ionophores, calcium ionophores, ammonium ionophores, chloride ion ionophores, and magnesium ionophores can be used.

[0038] The method for manufacturing such an ion-trapping unit 18 is not particularly limited, but for example, when using an ionophore, it can be manufactured in the following steps. First, polyvinyl chloride is weighed into a beaker. Here, as the polyvinyl chloride, it is preferable to use one with a degree of polymerization of about 1050 from the viewpoint of facilitating handling and smooth adhesion to the insulating composite layer 14.

[0039] Next, tetrahydrofuran is added to the beaker as a solvent and stirred with a stirrer until the polyvinyl chloride is dissolved.

[0040] Once the polyvinyl chloride is dissolved, a plasticizer, an ionophore, an anion eliminator (if the target to be measured is cationic), and a cation eliminator (if the target to be measured is anionic) are added, and the mixture is further stirred with a stirrer.

[0041] As plasticizers, for example, 2-nitrophenyl octyl ether (NPOE) and bis(2-ethylhexyl) sebacate can be used. As anion eliminators, for example, potassium tetrakis(4-chlorophenyl)borate can be used, and as cation eliminators, toridodecylmethylammonium chloride (TDDMACl) and disodium ethylenediaminetetraacetate (Na2EDTA) can be used.

[0042] The ionophore can be appropriately selected depending on the ion to be detected, for example, lithium ion (Li + If you want to detect potassium ions (K), you can use 6,6-Dibenzyl-1,4,8,11-tetraoxacyclotetradecane or 2,2,3,3-Tetramethyl-9-tetradecyl-1,4,8,11-tetraoxacyclotetradecane or potassium ions (K + If you want to detect ) Bis[(benzo-15-crown-5)-4-methyl]pimelate, sodium ion (Na + If you want to detect ) Bis[(12-crown-4)methyl] 2-dodecyl-2-methylmalonate, calcium ions (Ca 2+If you want to detect ) Bis(4-n-octylphenyl)phosphate, calcium salt, ammonium ion (NH4 + If you want to detect () nonactin, chloride ions (Cl - If you want to detect () 2,7-Di-tert-butyl-9,9-dimethyl-4,5-bis(N'-n-butylthioureido)xanthene, magnesium ion (Mg 2+ If you want to detect ), you can use 4,13-Bis[N-(1-adamantyl)carbamoylacetyl]-8-tetradecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane, 4-[N-(1-Adamantyl)carbamoylacetyl]-13-[N-(n-octadecyl)carbamoylacetyl]-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane, or 4,13-Bis[N-(cyclododecyl)carbamoylacetyl]-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane.

[0043] Next, the ion-trapping section 18 can be created by spreading the prepared solution on a glass petri dish and air-drying it. From the viewpoint of increasing the response speed (establishment of ion diffusion equilibrium), it is effective to make the ion-trapping section 18 thinner, and in this case, it is preferable to create the ion-trapping section 18 by spin coating.

[0044] In this ion trapping section 18, the weight fraction (X) of the anion eliminator and / or cation eliminator is greater than 0.0% by weight and 4.0% by weight or less, the weight fraction (Y) of the ionophore is 2.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less. As a result, even if the device 10 is used for an extended period under conditions of continuous gas supply, saturation of the potential response is less likely to occur, and the response to the gas concentration can be maintained for a long time. In this specification, "greater than" means the same as "greater than", and "greater than 0.0% by weight" means a value greater than 0.0% by weight, excluding 0.0% by weight.

[0045] In other preferred embodiments, X may be 0.1% by weight or more and 4.0% by weight or less, Y may be 2.0% by weight or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less, preferably X may be 0.2% by weight or more and 4.0% by weight or less, Y may be 2.0% by weight or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less, more preferably X may be 0.3% by weight or more and 4.0% by weight or less, and Y may be 2.0% by weight The amount of X may be % or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less, more preferably X may be 0.4% by weight or more and 4.0% by weight or less, Y may be 2% by weight or more and 8% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less, and even more preferably X may be 0.5% by weight or more and 4.0% by weight or less, Y may be 2.0% by weight or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less.

[0046] In other preferred embodiments, from the viewpoint of ensuring a longer saturation time, the ion trapping unit 18 may have X greater than 0.0% by weight and 4.0% by weight or less, Y 4.0% by weight or more and 8.0% by weight or less, and X + Y 4.0% by weight or more and 12.0% by weight or less, preferably X 0.1% by weight or more and 4.0% by weight or less, Y 4.0% by weight or more and 8.0% by weight or less, and X + Y 4.0% by weight The amount may be 12.0% by weight or less, and X may be 0.3% by weight or more and 4.0% by weight or less, Y may be 4.0% by weight or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less, and more preferably X is 0.5% by weight or more and 4.0% by weight or less, Y is 4.0% by weight or more and 8.0% by weight or less, and X + Y may be 4.0% by weight or more and 12.0% by weight or less.

[0047] In other preferred embodiments, the ion trapping unit 18 has an amount of X greater than 0.0% by weight and 4.0% by weight or less, Y greater than 2.5% by weight and 8.0% by weight or less, and X + Y greater than 4.0% by weight and 12.0% by weight or less, preferably X greater than 0.0% by weight and 4.0% by weight or less, Y greater than 3.0% by weight and 8.0% by weight or less, and X + Y greater than 4.0% by weight and 12.0% by weight or less, more preferably X greater than 0.1% by weight and 4.0% by weight or less, Y greater than 2.5% by weight and 8.0% by weight or less, and X + Y greater than 4.0% by weight and 12.0% by weight or less, and more preferably X greater than 0.3% by weight and 4.0% by weight or less, Y greater than 2.5% by weight and 8.0% by weight or less, and X + Y greater than 4.0% by weight and 12.0% by weight or less. The material is manufactured such that, more preferably, X is 0.5% by weight or more and 4.0% by weight or less, Y is 2.5% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less, more preferably, X is 0.1% by weight or more and 4.0% by weight or less, Y is 3.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less, more preferably, X is 0.3% by weight or more and 4.0% by weight or less, Y is 3.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less, and even more preferably, X is 0.5% by weight or more and 4.0% by weight or less, Y is 3.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less.

[0048] In other preferred embodiments, the ion trapping unit 18 is manufactured such that X is 0.3% by weight or more and 2.5% by weight or less, Y is 2.0% by weight or more and 7.0% by weight or less, and X + Y is 4.0% by weight or more and 9.5% by weight or less, preferably X is 0.5% by weight or more and 2.0% by weight or less, Y is 3.0% by weight or more and 6.0% by weight or less, and X + Y is 4.5% by weight or more and 8.0% by weight or less.

[0049] Furthermore, for such an ion capture unit 18, within the range that satisfies the weight fraction conditions described above, the value obtained by dividing the amount of substance of the contained ionophore by the amount of substance of the contained anion eliminator and / or cation eliminator is preferably 0.1 to 10, more preferably 1.0 to 3.0, and particularly preferably 1.5 to 2.5. By setting it within this range, a sufficient concentration potential response can be obtained, and the response time required for detection can be shortened.

[0050] The ion-capturing section 18 thus prepared can be cut to an appropriate size and attached to the insulating composite layer 14 so as not to trap air. The storage section 16 can then be bonded to the attached ion-capturing section 18 using, for example, epoxy resin, to create the device 10.

[0051] The insulating composite layer 14 is provided with an insulating film 146 at least in the area that comes into contact with the ion trapping section 18. The insulating film 146 also serves as a protective layer to protect the semiconductor layer 144 from the specimen and the ionization section 17. By providing the insulating film 146, corrosion of the semiconductor layer 144 can be prevented, and the durability and reliability of the semiconductor layer 144 can be improved. As for the material of the insulating film 146, any known insulating material can be used, and a corrosion-resistant material is preferred. Examples of insulating materials include Ta2O5, Si3N4, and SiO2. ｘ (where x satisfies 0 < x ≤ 2), and its thickness is preferably 0.01 μm or more and 0.5 μm or less, and more preferably 0.03 μm or more and 0.2 μm or less.

[0052] Furthermore, the semiconductor layer 144 has a field-effect mobility of 20 cm². 2 It is preferable that the value be 60 cm or higher, and especially 60 cm. 2 It is even more preferable that it be greater than or equal to / Vs.

[0053] Such a semiconductor layer 144 is composed of an oxide containing indium (In), zinc (Zn), and an additive element (M), the additive element (M) being at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).

[0054] Specifically, it is preferable that the atomic ratios of In and M satisfy the following formula (1) (wherein M is the sum of the content ratios of the added elements. The same applies to formulas (2) and (3) below): 0.4 ≤ (In + M) / (In + Zn + M) ≤ 0.8 (1) It is preferable that the atomic ratio of Zn satisfy the following formula (2): 0.2 ≤ Zn / (In + Zn + M) ≤ 0.6 (2) It is preferable that the atomic ratio of M satisfy the following formula (3): 0.001 ≤ M / (In + Zn + M) ≤ 0.015 (3)

[0055] When the atomic ratios of In, Zn, and M satisfy equations (1) to (3), the semiconductor layer 144 exhibits the field-effect mobility and OFF current described above.

[0056] In order for the semiconductor layer 144 to exhibit a higher field-effect mobility and a lower OFF current, it is more preferable that the atomic ratios of In, Zn, and M satisfy equations (1-2), (2-2), and (3-2). 0.43 ≤ (In + M) / (In + Zn + M) ≤ 0.79 (1-2) 0.21 ≤ Zn / (In + Zn + M) ≤ 0.57 (2-2) 0.0015 ≤ M / (In + Zn + M) ≤ 0.013 (3-2)

[0057] Furthermore, it is more preferable that the atomic ratios of In, Zn, and X satisfy equations (1-3), (2-3), and (3-3). 0.48 ≤ (In + M) / (In + Zn + M) ≤ 0.78 (1-3) 0.22 ≤ Zn / (In + Zn + M) ≤ 0.52 (2-3) 0.002 < M / (In + Zn + M) ≤ 0.012 (3-3)

[0058] Furthermore, it is more preferable that the atomic ratios of In, Zn, and M satisfy equations (1-4), (2-4), and (3-4). 0.53 ≤ (In + M) / (In + Zn + M) ≤ 0.75 (1-4) 0.25 ≤ Zn / (In + Zn + M) ≤ 0.47 (2-4) 0.0025 ≤ M / (In + Zn + M) ≤ 0.010 (3-4)

[0059] Furthermore, it is more preferable that the atomic ratios of In, Zn, and M satisfy equations (1-5), (2-5), and (3-5). 0.58 ≤ (In + M) / (In + Zn + M) ≤ 0.70 (1-5) 0.30 ≤ Zn / (In + Zn + M) ≤ 0.42 (2-5) 0.003 ≤ M / (In + Zn + M) ≤ 0.009 (3-5)

[0060] As described above, one or more additive elements (M) are selected from Ta, Sr, and Nb. These elements can be used individually or in combination of two or more. While additive elements (M) may include elements other than Ta, Sr, and Nb, it is preferable that they consist solely of these elements.

[0061] Furthermore, the thinner the semiconductor layer 144, the greater the change in conductivity of the surface layer, which in turn leads to a larger change in the moving charge, as will be described later, and thus improves measurement accuracy. The thickness of such a semiconductor layer 144 is preferably 0.5 μm or less, more preferably 0.1 μm or less, and particularly preferably 0.05 μm or less. There is no specific lower limit specified for the thickness of the semiconductor layer 144, but it is generally 0.005 μm or more.

[0062] Furthermore, it is preferable that the surface 144a of the semiconductor layer 144 on the ion trapping section 18 side be as smooth as possible. If the surface 144a of the semiconductor layer 144 is not smooth, for example, a gap may form between it and the insulating film 146, or the insulating film 146 may be formed discontinuously, reducing the adhesion between the insulating film 146 and the ion trapping section 18, making it impossible to accurately capture the potential change from the ion trapping section 18. As a result, the measurement accuracy may decrease or the operation may become unstable.

[0063] Specifically, the maximum height Sz of the surface 144a of the semiconductor layer 144 is preferably 0.05 μm or less, more preferably 0.01 μm or less, and most preferably 0.003 μm or less. There is no particular requirement for the lower limit of this maximum height Sz, but it is generally 0.0005 μm or more. Furthermore, the arithmetic mean height Sa of the surface 144a of the semiconductor layer 144 on the ion trapping portion 18 side is preferably 0.03 μm or less, more preferably 0.005 μm or less, and most preferably 0.002 μm or less. There is no particular requirement for the lower limit of this arithmetic mean height Sa, but it is generally 0.0002 μm or more.

[0064] Here, the maximum height Sz and the arithmetic mean height Sa are surface roughness parameters defined in ISO 25178, and such parameters can be measured, for example, by a 3D surface roughness shape measuring machine (Zygo, NexView). In this case, the measurement conditions are preferably carried out according to the following.

[0065] Measurements are performed in accordance with ISO 25178, using a 50x objective lens, a 20x zoom lens, and a measurement range of 89 μm × 87 μm. A roughness curve of 3 μm × 3 μm is extracted from the obtained three-dimensional surface shape, and the roughness curve is corrected using the analysis program "Mx" attached to the 3D surface roughness shape measuring machine under the following correction conditions to calculate the maximum height Sz and arithmetic mean height Sa.

[0066] <Correction Conditions> -Remove: Form Remove -Filter Type: Spline -Filter: Low Pass -Type: Gaussian Spline Auto

[0067] When forming the device 10 described above as an FET structure, it can be formed using the same methods as conventionally known FETs and MOSFETs. For example, it can be formed by depositing conductive metal thin films as the first electrode 141 and the second electrode 142 on an insulating substrate 12 using a sputtering apparatus, and then depositing an oxide thin film with the above-described configuration as the semiconductor layer 144 using a sputtering apparatus. A shadow mask can be used for patterning during the deposition of the first electrode 141 and the second electrode 142 and the semiconductor layer 144.

[0068] The conductive metals used as the first electrode 141 and the second electrode 142 are not particularly limited, but for example, molybdenum (Mo) or tungsten (W) can be used, and alloys of these metals with cerium oxide (CeO2), copper (Cu), silver (Ag), etc. can also be used.

[0069] Next, an insulating film 146 can be formed by depositing a ceramic thin film on top of this. Specifically, for example, the insulating film 146 can be formed by depositing a SiOx thin film using a plasma CVD apparatus such as the PD-2202L manufactured by Samco Corporation, under the conditions of a deposition gas: SiH4 / N2O / N2 mixed gas, deposition pressure: 110 Pa, and substrate temperature: 250°C to 400°C.

[0070] Furthermore, the control device 60 of the concentration measuring device 50 in this embodiment includes a variable voltage source 32 (voltage application means) for applying a voltage between the first electrode 141 and the second electrode 142, and an ammeter 36 (current measuring means) for measuring the current value between the first electrode 141 and the second electrode 142.

[0071] The control device 60 has a computer equipped with calculation means, storage means, input / output means, etc., and is configured to control the applied voltage of the variable voltage source 32 and measure the current value of the ammeter 36 based on a program stored in the storage means.

[0072] Furthermore, the control device 60 further includes an electrode-to-electrode current detection means 61. The electrode-to-electrode current detection means 61 is configured to control the voltage applied by the variable voltage source 32 and to receive the current value measured by the ammeter 36 as an electrical signal. Such an electrode-to-electrode current detection means 61 can be implemented by a computer or the like incorporated into the control device 60.

[0073] The electrode current detection means 61 uses a variable voltage source 32 to detect a predetermined voltage V between the first electrode 141 and the second electrode 142. ds With the current applied, the inter-electrode current I flowing between the first electrode 141 and the second electrode 142 is measured by the ammeter 36. ds Detects.

[0074] Here, a predetermined voltage V ds The voltage is not particularly limited as long as it is large enough to allow current to flow through the semiconductor layer 144. In this embodiment, a predetermined voltage V ds Since it is sufficient to apply a constant voltage, the system can also be configured to use a constant voltage source instead of the variable voltage source 32.

[0075] The inter-electrode current I detected in this manner ds The magnitude of the current I correlates with the amount of ions captured by the ion capture unit 18, that is, with the concentration of the target substance in the sample. For example, the concentration of the target substance and the inter-electrode current I ds By creating a calibration curve in advance that shows the relationship between the electrode current I measured using the concentration measuring device 50, ds Based on this, the concentration of the substance being detected can be determined.

[0076] Alternatively, the concentration of the substance being detected and the electrode current I ds By associating these with each other and using them as training data, machine learning is performed, and artificial intelligence (AI) is used to determine the inter-electrode current I measured using the concentration measuring device 50. ds It is also possible to determine the concentration of the substance being detected based on this.

[0077] The control device 60 of this embodiment further comprises a concentration calculation means 64, which calculates the inter-electrode current I detected by the inter-electrode current detection means 61. dsBased on this, the device is configured to calculate the concentration of the substance to be detected, as described above. Such a concentration calculation means 64 can be implemented by a computer incorporated into the control device 60.

[0078] Figure 3 is a schematic diagram showing a modified version of the device 10 used in the concentration measuring device 50 shown in Figure 1. Since this concentration measuring device 50 has basically the same configuration as the concentration measuring device 50 shown in Figures 1 and 2, the same reference numerals are used for similar components, and their detailed explanations are omitted.

[0079] In the concentration measuring device 50 of this embodiment, the ionization unit 17 has a gas-permeable membrane 17a. The gas-permeable membrane 17a has the property of selectively allowing only the desired gas to pass through. Examples of such a gas-permeable membrane 17a include polydimethylsiloxane (PDMS).

[0080] By configuring the sample in this way, even when the sample is a gas containing multiple components, the gas-permeable membrane 17a allows only the gas containing the target to be detected to pass through, thereby improving the selectivity of the target to be detected and enabling more accurate detection of the presence and concentration of the target in the sample.

[0081] Figure 4 is a schematic diagram illustrating the configuration of another embodiment of the concentration measuring device of the present invention. Since this concentration measuring device 50 has basically the same configuration as the concentration measuring devices 50 shown in Figures 1 to 3, the same reference numerals are used for similar components, and their detailed explanations are omitted.

[0082] In the concentration measuring device 50 of this embodiment, the ionization section 17 is a liquid, and the device further includes a reference electrode 161 as a third electrode that comes into contact with the liquid ionization section 17. The control device 60 also includes a variable voltage source 34 (voltage application means) for applying a voltage between the first electrode 141 and the reference electrode 161, and a voltmeter 38 (voltage measurement means) for measuring the voltage value between the first electrode 141 and the reference electrode 161.

[0083] In this embodiment, the control device 60 has a computer equipped with calculation means, storage means, input / output means, etc., and is configured to control the applied voltage of the variable voltage source 32 and variable voltage source 34, measure the current value using the ammeter 36, and measure the voltage value using the voltmeter 38, based on a program stored in the storage means.

[0084] Furthermore, the control device 60 further includes a threshold voltage detection means 62. The threshold voltage detection means 62 controls the voltage applied by the variable voltage source 32 and the variable voltage source 34, and is configured to receive current and voltage values ​​measured by the ammeter 36 and the voltmeter 38 as electrical signals. Such a threshold voltage detection means 62 can be implemented by a computer or the like incorporated into the control device 60.

[0085] The threshold voltage detection means 62 uses a variable voltage source 32 to determine a predetermined voltage V between the first electrode 141 and the second electrode 142. ds With the voltage applied, the variable voltage source 34 applies a voltage V between the first electrode 141 and the reference electrode 161. g The current is gradually increased. The threshold voltage detection means 62 then uses the ammeter 36 to determine the current I flowing between the first electrode 141 and the second electrode 142. d The change is detected, and the voltage V between the first electrode 141 and the reference electrode 161 is detected by the voltmeter 38. g By detecting changes in the threshold voltage V th Measure.

[0086] In this case, the semiconductor layer 144, in the device 10 having the configuration described above, sets the voltage applied to the reference electrode 161 to a threshold voltage V th When the following conditions are met, the OFF current, which is the current flowing from the first electrode 141 to the second electrode 142 or from the second electrode 142 to the first electrode 141, is 1 × 10⁻¹⁰ -12 It is preferable that it be A or less, and especially 1 × 10 -14 It is even more preferable that it be less than or equal to A. Because the OFF current is small in this way, the threshold voltage V will be reduced, as will be described later. th When detecting the threshold voltage V, even if the voltage applied between the first electrode 141 and the second electrode 142 is small, the threshold voltage V can be detected with higher accuracy. thIt can be detected.

[0087] In the device 10 having the configuration described above, the threshold voltage V th It is known that this threshold voltage V changes depending on the amount of ions to be detected that are captured by the ion capture unit 18. th By measuring this, the concentration of the target substance contained in the sample can be detected.

[0088] Note that the threshold voltage V th The measurement method is not particularly limited, and for example, a current I between the first electrode 141 and the second electrode 142 d Voltage V when the current starts to flow g It may also detect current I d When the current is flowing, the voltage V g Gradually decrease the current I d Voltage V at which the current stops flowing g It may also detect voltage V. g By changing the current I d is a predetermined value (for example, 1 × 10) -9 V when A) is reached ds The value of the threshold voltage V th While conventional methods can be used, such as the above, from the perspective of more accurate measurement, voltage V ds Assuming that is constant, the voltage V g A certain range is applied, and the current I that flows at that time is applied. d Measure and V within a predetermined range. g √I d The approximate line is calculated using the least squares method, and the √I of that approximate line is calculated. d V when = 0 g threshold voltage V th It is preferable to do so.

[0089] The threshold voltage V measured in this manner th Since there is a correlation between the concentration of the substance being detected and the threshold voltage V, for example, the concentration of the substance being detected and the threshold voltage V th By creating a calibration curve in advance that shows the relationship with the threshold voltage V measured using the concentration measuring device 50, th Based on this, the concentration of the substance being detected can be determined.

[0090] Alternatively, the concentration of the substance being detected and the threshold voltage V th By associating these with each other and using them as training data, machine learning is performed, and artificial intelligence (AI) is used to determine the threshold voltage V measured using the concentration measuring device 50. th It is also possible to determine the concentration of the substance being detected based on this.

[0091] The concentration calculation means 64 of this embodiment uses the threshold voltage V detected by the threshold voltage detection means 62. th Based on this, the device is configured to calculate the concentration of the substance to be detected, as described above. Such a concentration calculation means 64 can be implemented by a computer incorporated into the control device 60.

[0092] Figure 5 is a schematic front view showing a modified example of the device 10 used in the concentration measuring device 50 shown in Figure 4, and Figure 6 is a schematic side view of the device 10 shown in Figure 5. Since this concentration measuring device 50 has basically the same configuration as the concentration measuring devices 50 shown in Figures 1 to 4, the same reference numerals are used for similar components, and their detailed explanations are omitted.

[0093] In the concentration measuring device 50 of this embodiment, as shown in Figures 5 and 6, a gate electrode layer 13 is provided between the insulating substrate 12 and the insulating composite layer 14. The gate electrode layer 13 has a gate electrode 131, which is a third electrode formed on the insulating substrate 12, and an insulating film 132 for insulating the space between the gate electrode 131 and the insulating composite layer 14.

[0094] Even when the gate electrode layer 13 is provided in this manner, the voltage V between the first electrode 141 and the gate electrode 131 can be measured by the voltmeter 38, similar to the concentration measuring device 50 shown in Figure 4. g By detecting changes in the threshold voltage V th By measuring the threshold voltage V th Based on this, the concentration of the substance being detected can be determined.

[0095] (Example) For ion trapping units 18, the potential response characteristics to changes in gas concentration and the saturation time (lifetime) of the potential change were evaluated for each unit prepared by changing the blending weights of the base material, plasticizer, ionophore, and anion exclusion agent.

[0096] In this example, polyvinyl chloride (PVC) was used as the base material, bis(2-ethylhexyl) sebacate as the plasticizer, nonactin as the ionophore, and potassium tetrakis(4-chlorophenyl)borate (K-TCPB) as the anion eliminator. The weight fractions of each component are shown in Table 1.

[0097] Using the ion capture unit 18 equipped with the fabricated ionization unit 17, the concentration of a nitrogen-ammonia mixed gas containing ammonia, the target of detection, was measured as the test subject, and the saturation time of the device 10 was evaluated. Specifically, nitrogen gas was supplied to stabilize the device 10 for more than one hour, and the threshold voltage V th Continue the measurement. Then, supply a nitrogen-ammonia mixed gas with an ammonia concentration of 30 ppm and the threshold voltage V th The following measurement is performed. At this time, the threshold voltage V is measured within the section where the nitrogen-ammonia mixed gas is supplied, with the start time of supply of the nitrogen-ammonia mixed gas as the reference. th The time it takes for the voltage to reach its minimum is evaluated as the "saturation time". In this specification, "threshold voltage V th "When the threshold voltage V is minimized" means that after supplying the nitrogen-ammonia mixed gas, the threshold voltage V th This means that the change takes the minimum value in a relatively stable interval, excluding instantaneous minimums caused by temporary fluctuations or noise, for example. It also considers the presence or absence of a potential response to gas concentration changes, i.e., the threshold voltage V when nitrogen gas is supplied. th And the threshold voltage V when a nitrogen-ammonia mixed gas is supplied. th We also evaluated whether there was a statistically significant difference between the two.

[0098]

[0099] Here, regarding the potential response, a clear threshold voltage V is obtained in response to the change in gas concentration. th When a change in the threshold voltage V is observed, it is marked with "◎". th If a change is observed but the change is small, it is marked with "○", and the threshold voltage V th We evaluated instances where no change was observed as "×".

[0100] Figure 7(a) is a graph showing the measurement results for sample 8, and Figure 7(b) is a graph showing the measurement results for sample 9. In comparative examples, samples 8 and 9 have an anion exclusion agent content of 0% by weight, so no potential response is obtained even when a nitrogen-ammonia mixed gas is supplied, and the threshold voltage V th No change was observed. Therefore, the saturation time could not be measured. In the graph in Figure 7, the threshold voltage is shown as a plot and the ammonia concentration as a dashed line.

[0101] Figure 8 is a graph showing the measurement results for sample 7. Although a potential response was observed in sample 7, which is a comparative example, the saturation time was short (approximately 20 minutes), confirming that it is not suitable for long-term continuous use. In the graph in Figure 8, the threshold voltage is plotted, and the ammonia concentration is represented by a dashed line. The threshold voltage V th The plots where the value is minimized are circled.

[0102] In contrast, in the examples of samples 1 to 6, a long saturation time of 30 minutes or more was ensured while maintaining the potential response, confirming that the gas concentration could be measured stably for a long period of time. Figures 9 and 10 show graphs of the measurement results for samples 1 to 6. In the graphs of Figures 9 and 10, the threshold voltage is represented by a plot and the ammonia concentration by a dashed line. The threshold voltage V th The plots where the value is minimized are circled.

[0103] From these results, it became clear that both voltage responsiveness and extended lifespan can be achieved by setting the weight fraction of the anion eliminator (X) to more than 0.0% by weight and 4.0% by weight or less, the weight fraction of the ionophore (Y) to 2.0% by weight or more and 8.0% by weight or less, and further setting the total weight fraction of these (X + Y) to 4.0% by weight or more and 12.0% by weight or less.

[0104] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications are possible without departing from the object of the present invention.

[0105] 10 Device 12 Insulating substrate 13 Gate electrode layer 131 Gate electrode 132 Insulating film 14 Insulating composite layer 141 First electrode 142 Second electrode 144 Semiconductor layer 144a Surface 146 Insulating film 16 Storage section 16a Partition section 161 Reference electrode 17 Ionization section 17a Gas permeable film 18 Ion trapping section 19 Ionic liquid 32 Variable voltage source 34 Variable voltage source 36 Ammeter 38 Voltmeter 50 Concentration measuring device 60 Control device 61 Inter-electrode current detection means 62 Threshold voltage detection means 64 Concentration calculation means

Claims

1. A device comprising an insulating substrate, at least one insulating composite layer, and a storage section capable of storing a sample, wherein the insulating composite layer has a pair of electrodes and a semiconductor layer in contact with the pair of electrodes, the storage section has an ionization section for ionizing a target to be detected in the sample, and between the insulating composite layer and the storage section is an ion capture section comprising an ionophore for capturing the ionized target to be detected and an anion eliminator and / or a cation eliminator, wherein the weight fraction (X) of the anion eliminator and / or cation eliminator is greater than 0.0% by weight and 4.0% by weight or less, the weight fraction (Y) of the ionophore is 2.0% by weight or more and 8.0% by weight or less, and X + Y is 4.0% by weight or more and 12.0% by weight or less.

2. The device according to claim 1, wherein X is 0.1% by weight or more and 4.0% by weight or less.

3. The device according to claim 1, wherein Y is 2.5% by weight or more and 8.0% by weight or less.

4. The device according to claim 1, wherein X is 0.1% by weight or more and 4.0% by weight or less, and Y is 2.5% by weight or more and 8.0% by weight or less.

5. The device according to claim 1, wherein the semiconductor layer is composed of an oxide containing indium (In), zinc (Zn), and an additive element (M), and the additive element (M) includes at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).

6. The device according to claim 1, wherein the ionization portion includes a gas-permeable membrane.

7. The device according to claim 1, wherein the ionization portion is in the form of a gel.

8. The device according to claim 1, wherein the ionization portion is a solid electrolyte having an electrode catalyst.

9. The device according to claim 1, wherein the ionization portion is a liquid and further comprises a third electrode in contact with the liquid.

10. The device according to claim 1, further comprising a third electrode formed on the insulating substrate in an insulated state from the insulating composite layer.

11. The field-effect mobility of the semiconductor layer is 20 cm². 2 The device according to claim 1, wherein / Vs is greater than or equal to Vs.

12. The OFF current between the pair of electrodes in the semiconductor layer is 1 × 10 -12 The device according to claim 1, wherein A is less than or equal to A.

13. A concentration measuring device comprising: a device according to any one of claims 1 to 12; a control device, the control device comprising: a voltage applying means for applying a voltage between the pair of electrodes; a current measuring means for measuring the current flowing between the pair of electrodes when a voltage is applied by the voltage applying means; and a concentration calculating means for calculating the concentration of a target to be detected in the subject based on the inter-electrode current measured by the current measuring means.

14. A device according to claim 9 or 10, and a control device, wherein the control device includes: a voltage applying means for varying the voltage applied between the electrode into which current flows and the third electrode; a current measuring means for measuring the current flowing between the pair of electrodes; and a threshold voltage V, which is the voltage value of the third electrode when it switches whether or not current flows between the pair of electrodes, based on the voltage value applied by the voltage applying means and the current value measured by the current measuring means. th A threshold voltage detection means for detecting the threshold voltage V detected by the threshold voltage detection means th A concentration measuring device comprising a concentration calculation means for calculating the concentration of a target to be detected in the subject based on the above.

15. A concentration measurement method for detecting the concentration of a target to be detected in a sample using the device described in any one of claims 1 to 12, comprising: measuring the inter-electrode current, which is the value of the current flowing between the pair of electrodes when a voltage is applied between the pair of electrodes; and measuring the concentration of the target to be detected in the sample based on the inter-electrode current.

16. A concentration measurement method for detecting the concentration of a target to be detected in a sample using the device according to claim 9 or 10, wherein the threshold voltage V is the voltage value of the third electrode when it switches whether or not current flows between the pair of electrodes. th Detect the threshold voltage V th A method for measuring concentration, which measures the concentration of a target substance in a sample based on the above.

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