Device, concentration measurement apparatus provided with same, and concentration measurement method using same
Patent Information
- Application Number
- PCT/JP2026/011536
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-27
- Filing Date
- 2026-03-23
- Publication Date
- 2026-10-01
Smart Images
Figure JP2026011536_01102026_PF_FP_ABST
Abstract
Description
Device, concentration measuring apparatus equipped therewith, and concentration measuring method using the same.
[0001] This invention relates to the magnitude of the current flowing between a pair of electrodes according to the concentration of the substance to be detected in the sample, and the threshold voltage V, which is the voltage value of the third electrode when it switches between whether or not current flows between the pair of electrodes. th Regarding devices where the current magnitude and threshold voltage V change, more specifically, the magnitude of the current and threshold voltage V th This invention relates to a concentration measuring device and a concentration measuring method for measuring the concentration of a target substance in a subject based on changes in that concentration.
[0002] In the coming super-smart society, Society 5.0, the goal is to achieve both economic development and the resolution of social issues, and the IoT that supports this will require sensors for data acquisition.
[0003] Conventionally, electrochemical sensors using semiconductors have been known as a method for detecting the presence or concentration of specific components in a gas. A conventional gas sensor 200, for example, as shown in Figure 10, has a configuration comprising a pair of electrodes 241 and 242 on an insulating substrate 212, and a semiconductor layer 244 that is in contact with the pair of electrodes 241 and 242. In such a gas sensor 200, when it comes into contact with the gas being tested, the target substance to be detected in the test sample is adsorbed onto the semiconductor layer 244, and the resistance value of the semiconductor layer 244 changes. By measuring this change in the resistance value of the semiconductor layer 244, the presence or concentration of the target substance to be detected in the test sample can be detected.
[0004] In general, tin oxide (SnO2) is used as the semiconductor layer 244 of such a gas sensor 200. However, because the tin oxide semiconductor layer 244 adsorbs any gas molecule, it has low selectivity for the target to be detected, and in some cases, it is not possible to accurately detect the presence or concentration of a specific target.
[0005] Furthermore, some gas sensors have an insulating film formed on the semiconductor layer 244 for the purpose of protecting the semiconductor layer 244. However, the insulating film also has the problem of adsorbing any gas molecule, resulting in low selectivity for the object to be detected.
[0006] Furthermore, in such gas sensors, accurate detection may be difficult in some cases due to the small change in the resistance value of the semiconductor layer 244. In this case, heating the semiconductor layer 244 to increase the temperature can also increase the change in the resistance value of the semiconductor layer 244, but a mechanism for heating the semiconductor layer 244 is required, and the energy required for measurement also increases.
[0007] In order to solve such problems, the inventors of the present invention ionize a detection target in an analyte, and capture the ionized detection target by an ion trapping portion such as an ionophore or an ionic liquid that can selectively trap specific ions, and have developed a device in which the detected current value or voltage value changes according to the amount of trapped ions.
[0008] However, it has been found that when an ionophore or an ionic liquid is used as the ion trapping portion, as the usage time of the device elapses, components such as the ionophore precipitate in the ion trapping portion, resulting in a decrease in ion detection performance.
[0009] In view of such a current situation, an object of the present invention is to provide a device that can be used in a concentration measuring apparatus and a concentration measuring method, which can accurately detect the presence / absence and concentration of a detection target, in which the decrease in ion detection performance is slight even if components such as an ionophore precipitate in the ion trapping portion as the usage time of the device elapses.
[0010] The present invention has been made to solve the above-mentioned problems in the prior art, and the device of the present invention, the concentration measuring apparatus including the same, and the concentration measuring method using the same include those configured as follows.
[0011] [1] A device comprising: an insulating substrate; at least one insulating composite layer; and a storage section capable of storing an analyte, wherein the insulating composite layer comprises a pair of electrodes and a semiconductor layer in contact with the pair of electrodes, the storage section has an ionization section that ionizes an analyte to be detected in the analyte, an ion trapping section comprising an ionophore that traps the ionized analyte to be detected, and an anion excluding agent and / or a cation excluding agent is provided between the insulating composite layer and the storage section, and a weight fraction of a total weight of the ionophore and the anion excluding agent and / or the cation excluding agent in the ion trapping section is 0.2 wt% to 4.0 wt%.
[0012] [2] The device according to [1], wherein a value obtained by dividing an amount of substance of the ionophore by an amount of substance of the anion excluding agent and / or the cation excluding agent is 0.1 to 10.
[0013] [3] The device according to [1] or [2], wherein the semiconductor layer is formed of an oxide containing indium (In), zinc (Zn) and an additional element (X), and the additional element (X) contains at least one element selected from the group consisting of tantalum (Ta), strontium (Sr) and niobium (Nb).
[0014] [4] The device according to any one of [1] to [3], wherein the ionization section comprises a gas permeable membrane.
[0015] [5] The device according to any one of [1] to [4], wherein the ionization section is gel-shaped.
[0016] [6] The device according to any one of [1] to [5], wherein the ionization section is a solid electrolyte having an electrode catalyst.
[0017] [7] The device according to any one of [1] to [6], wherein the ionization section is a liquid, and the device further comprises a third electrode in contact with the liquid.
[0018] [8] The device according to any one of [1] to [7], further comprising a third electrode formed on the insulating substrate in a state insulated from the insulating composite layer.
[0019] [9] The field effect mobility of the semiconductor layer is 20 cm 2 A device according to any of [1] to [8], which is greater than or equal to / Vs.
[0020]
[10] 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 [9].
[0021]
[11] A concentration measuring device comprising a device described in any of [1] to
[10] 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 a target to be detected in the subject based on the inter-electrode current measured by the current measuring means.
[0022]
[12] The device comprises the device described in [7] or [8] 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.
[0023]
[13] A concentration measurement method for detecting the concentration of a target to be detected in a subject using a device described in any of [1] to
[10] , 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 subject based on the inter-electrode current.
[0024]
[14] A concentration measurement method for detecting the concentration of a target to be detected in a subject using the device described in [7] or [8], 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.
[0025] According to the present invention, by limiting the weight fraction of the total weight of the ionophore and the anion eliminator and / or cation eliminator in the ion trapping section to 0.2% to 4.0% by weight, even after the device has been in use for a considerable time, the emission of material in the ion trapping section is limited, the decrease in ion detection performance is minimal, and the presence and concentration of the target object can be accurately detected.
[0026] Figure 1 is a schematic diagram illustrating the configuration of the concentration measuring device in this embodiment. Figure 2 is a schematic diagram illustrating the configuration of the device used in the concentration measuring device of Figure 1. Figure 3 is a schematic diagram showing a modified example of the device used in the concentration measuring device shown in Figure 1. Figure 4 is a schematic diagram illustrating the configuration in another embodiment of the concentration measuring device of the present invention. Figure 5 is a schematic front view showing a modified example of the device used in the concentration measuring device shown in Figure 4. Figure 6 is a schematic side view of the device shown in Figure 5. Figure 7 is a graph showing the change in gas concentration and the change in threshold voltage Vth when measuring the concentration potential response. Figure 8(a) is a microscope image showing the appearance of sample 1, and Figure 8(b) is a microscope image showing the appearance of sample 8. Figure 9(a) is a microscope image showing the appearance of sample 4, and Figure 9(b) is a microscope image showing the appearance of sample 5. Figure 10 is a schematic diagram illustrating the configuration of a conventional gas sensor.
[0027] 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.
[0028] 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.
[0029] Furthermore, in this specification, the term "third electrode" includes both the reference electrode and the gate electrode.
[0030] 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.
[0031] 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).
[0032] The insulating substrate 12 is a substrate made of an insulating material such as glass or ceramics.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] Next, tetrahydrofuran is added to the beaker as a solvent and stirred with a stirrer until the polyvinyl chloride is dissolved.
[0039] Once the polyvinyl chloride is dissolved, a plasticizer, an ionophore, an anion eliminator (if the target to be detected is a cation), and a cation eliminator (if the target to be detected is an anion) are added, and the mixture is further stirred with a stirrer.
[0040] As the plasticizer, for example, 2-nitrophenyl octyl ether (NPOE), bis(2-ethylhexyl) sebacate, or the like can be used. As the anion excluder, for example, potassium tetrakis(4-chlorophenyl)borate or the like can be used, and as the cation excluder, tridodecylmethylammonium chloride (TDDMACl), disodium ethylenediaminetetraacetate (Na₂EDTA) or the like can be used.
[0041] The ionophore can be appropriately selected according to the ion to be detected. For example, when it is desired to detect a lithium ion (Li + ), dibenzyl-14-crown-4 or TTD-14-crown-4 can be used; when it is desired to detect a potassium ion (K + ), bis(benzo-15-crown-5) can be used; when it is desired to detect a sodium ion (Na + ), bis(12-crown-4) can be used; when it is desired to detect a calcium ion (Ca 2+ ), HDOPP-Ca can be used; when it is desired to detect an ammonium ion (NH₄ + ), nonactin can be used; when it is desired to detect a chloride ion (Cl - ), Bisthiourea-1 can be used; when it is desired to detect a magnesium ion (Mg 2+ ), C₁₄-K₂₂B₅, K₂₂B₁B₅, or K₂₂B₉ can be used.
[0042] Next, the solution prepared as described above is spread on a glass petri dish and air-dried, whereby the ion trapping portion 18 can be formed. From the viewpoint of increasing the response speed (establishment of ion diffusion equilibrium), reducing the thickness of the ion trapping portion 18 is effective, and in this case, it is preferable to produce the ion trapping portion 18 by spin coating.
[0043] Furthermore, it is preferable that the ion capture unit 18 is manufactured such that the weight fraction of the total weight of the ionophore and the anion eliminator and / or cation eliminator is 0.2% by weight to 4.0% by weight. By setting the weight fraction of the total weight of the ionophore and the anion eliminator and / or cation eliminator to 4.0% by weight or less, even after the device 10 has been in use for a considerable amount of time, the formation emission in the ion capture unit is limited, and the decrease in ion detection performance is minimal. On the other hand, by setting the weight fraction of the total weight of the ionophore and the anion eliminator and / or cation eliminator to 0.2% by weight or more, sufficient ion detection performance can be ensured. Moreover, it is even more preferable that the weight fraction of the total weight of the ionophore and the anion eliminator and / or cation eliminator be 3.0% by weight or less, which further suppresses the occurrence of formation emission during long-term use. Furthermore, the weight fraction of the total weight of the ionophore and the anion and / or cation eliminator is more preferably 0.3% by weight or more, which can further improve ion detection performance. For this reason, the weight fraction of the total weight of the ionophore and the anion and / or cation eliminator can be in the range of, for example, 0.3% to 4.0% by weight, 0.2% to 3.0% by weight, or 0.3% to 3.0% by weight.
[0044] Furthermore, for such an ion trapping unit 18, 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, it becomes possible to achieve both the concentration potential response amount, which will be described later, and the response time required for detection.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] Such a semiconductor layer 144 is composed of an oxide containing indium (In), zinc (Zn), and an additive element (X), the additive element (X) being at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).
[0049] Specifically, it is preferable that the atomic ratios of In and X satisfy the following formula (1) (wherein X is the sum of the content ratios of the added elements. The same applies to formulas (2) and (3) below): 0.4 ≤ (In + X) / (In + Zn + X) ≤ 0.8 (1) It is preferable that the atomic ratio of Zn satisfy the following formula (2): 0.2 ≤ Zn / (In + Zn + X) ≤ 0.6 (2) It is preferable that the atomic ratio of X satisfy the following formula (3): 0.001 ≤ X / (In + Zn + X) ≤ 0.015 (3)
[0050] When the atomic ratios of In, Zn, and X satisfy equations (1) to (3), the semiconductor layer 144 exhibits the field-effect mobility and OFF current described above.
[0051] 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 X satisfy equations (1-2), (2-2), and (3-2). 0.43 ≤ (In + X) / (In + Zn + X) ≤ 0.79 (1-2) 0.21 ≤ Zn / (In + Zn + X) ≤ 0.57 (2-2) 0.0015 ≤ X / (In + Zn + X) ≤ 0.013 (3-2)
[0052] 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 + X) / (In + Zn + X) ≤ 0.78 (1-3) 0.22 ≤ Zn / (In + Zn + X) ≤ 0.52 (2-3) 0.002 < X / (In + Zn + X) ≤ 0.012 (3-3)
[0053] Furthermore, it is more preferable that the atomic ratios of In, Zn, and X satisfy equations (1-4), (2-4), and (3-4). 0.53 ≤ (In + X) / (In + Zn + X) ≤ 0.75 (1-4) 0.25 ≤ Zn / (In + Zn + X) ≤ 0.47 (2-4) 0.0025 ≤ X / (In + Zn + X) ≤ 0.010 (3-4)
[0054] Furthermore, it is more preferable that the atomic ratios of In, Zn, and X satisfy equations (1-5), (2-5), and (3-5). 0.58 ≤ (In + X) / (In + Zn + X) ≤ 0.70 (1-5) 0.30 ≤ Zn / (In + Zn + X) ≤ 0.42 (2-5) 0.003 ≤ X / (In + Zn + X) ≤ 0.009 (3-5)
[0055] As described above, one or more additive elements (X) are selected from Ta, Sr, and Nb. These elements can be used individually or in combination of two or more. Additive elements (X) may include elements other than Ta, Sr, and Nb, but preferably they consist only of these elements.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] <Correction Conditions> -Remove: Form Remove -Filter Type: Spline -Filter: Low Pass -Type: Gaussian Spline Auto
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] Furthermore, the control device 60 further includes an electrode current detection means 61. The 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 current detection means 61 can be implemented by a computer or the like incorporated into the control device 60.
[0068] 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.
[0069] 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.
[0070] 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, dsBased on this, the concentration of the substance being detected can be determined.
[0071] 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.
[0072] 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. ds 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.
[0073] 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.
[0074] 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).
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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 thWhen 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. th It can be detected.
[0082] 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.
[0083] 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 = 0g The threshold voltage V th It is preferable to do so.
[0084] 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.
[0085] 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.
[0086] 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.
[0087] 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.
[0088] 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.
[0089] 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.
[0090] (Example) For ion trapping units 18, the degree of formation after a predetermined time was visually confirmed for each unit prepared by varying the blending weights of polyvinyl chloride, plasticizer, ionophore, and anion exclusion agent. The concentration potential response is shown in Table 1 as an indicator of the performance of concentration measurement.
[0091]
[0092] The degree of deposition is judged visually, with ◎ indicating almost no deposition throughout the entire ion-trapping section 18, ○ indicating deposition only on the periphery of the ion-trapping section 18, △ indicating some deposition in the central part of the ion-trapping section 18, and × indicating deposition throughout the entire ion-trapping section 18.
[0093] Furthermore, in this specification, the concentration potential response is defined as the threshold voltage V, as shown in Figure 7, while sequentially changing the ammonia gas concentration in the nitrogen-ammonia mixed gas introduced into the storage unit 16. th The threshold voltage V was measured when the gas concentration was 0.5 ppm. th The maximum value and the threshold voltage V when the gas concentration is 10 ppm. th This represents the difference from the minimum value. If such a concentration-potential response is large, the threshold voltage V for the change in concentration will be large. th This results in a large change, making it possible to accurately measure the concentration.
[0094] When the total amount of ionophore and anion exclusion agent in the ion capture unit 18 is 5.0% by weight (Sample 1), as shown in Figure 8(a), the formation emission spreads throughout, degrading the ion detection performance. Also, when the total amount of ionophore and anion exclusion agent in the ion capture unit 18 is 0.1% by weight (Sample 8), as shown in Figure 8(b), almost no formation emission is observed, but the concentration potential response is small, making it difficult to perform accurate concentration measurements.
[0095] In contrast, for samples 2 to 7, the compound analysis was limited, and the decrease in ion detection performance was minimal. For example, Figure 9(a) is a microscopic image showing the appearance of sample 4, and Figure 9(b) is a microscopic image showing the appearance of sample 5.
[0096] The microscope images shown in Figures 8 and 9 were captured for each sample using a Keyence VK-X3000 laser microscope, and representative portions are shown in magnified view.
[0097] Furthermore, for samples 2 to 7, the concentration-potential response also showed good values of 60 mV or higher, allowing for accurate measurement of concentration.
[0098] 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.
[0099] 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 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 of the total weight of the ionophore and the anion eliminator and / or the cation eliminator in the ion capture section is 0.2% by weight to 4.0% by weight.
2. The device according to claim 1, wherein the value obtained by dividing the amount of substance of the ionophore by the amount of substance of the anion eliminator and / or the cation eliminator is 0.1 to 10.
3. The device according to claim 1, wherein the semiconductor layer is composed of an oxide containing indium (In), zinc (Zn), and an additive element (X), and the additive element (X) includes at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).
4. The device according to claim 1, wherein the ionization portion includes a gas-permeable membrane.
5. The device according to claim 1, wherein the ionization portion is in the form of a gel.
6. The device according to claim 1, wherein the ionization portion is a solid electrolyte having an electrode catalyst.
7. The device according to claim 1, wherein the ionization portion is a liquid and further comprises a third electrode in contact with the liquid.
8. 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.
9. 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.
10. 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.
11. A concentration measuring device comprising: a device according to any one of claims 1 to 10; 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 a target to be detected in the subject based on the inter-electrode current measured by the current measuring means.
12. A device according to claim 7 or 8, 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.
13. 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 10, 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.
14. A concentration measurement method for detecting the concentration of a target to be detected in a sample using the device described in claim 7 or 8, 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.