Device, concentration measurement apparatus provided with same, and concentration measurement method using same

Abstract

[Problem] The present invention provides a device that can be used for a concentration measurement apparatus and a concentration measurement method, with which it is possible to selectively detect an object to be detected in a test subject and to accurately detect the presence or absence of a specific object to be detected and the concentration thereof with small energy. [Solution] Provided is a device that has an insulating substrate, at least one insulating composite layer, and a retainer part in which a test subject can be retained, wherein: the insulating composite layer has a pair of electrodes and a semiconductor layer which is in contact with the pair of electrodes; the retainer part has an ionization part for ionizing an object to be detected in the test subject; and an ion capturing part for capturing the ionized object to be detected is provided between the insulating composite layer and the retainer part.

Description

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

[0001] The present invention relates to a method for detecting a current flowing between a pair of electrodes in accordance with the concentration of a target substance in a test sample, and a threshold voltage V, which is a voltage value of the third electrode at which a current flows between the pair of electrodes. th More specifically, the magnitude of such current and the threshold voltage V th The present invention relates to a concentration measuring device and a concentration measuring method for measuring the concentration of a target substance in a test fluid based on a change in the concentration of the target substance.

[0002] Society 5.0, the coming super-smart society, aims to achieve both economic development and the resolution of social issues, and the IoT that will support this will require sensors to collect data.

[0003] Electrochemical sensors using semiconductors have been known as a method for detecting the presence or absence and concentration of specific components in gas. A conventional gas sensor 200, for example, as shown in FIG. 10 , has 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 gas sensor 200, upon contact with a gas that is an analyte, the analyte in the analyte is adsorbed to the semiconductor layer 244, causing a change in the resistance value of the semiconductor layer 244. By measuring this change in the resistance value of the semiconductor layer 244, the presence or absence and concentration of the analyte in the analyte can be detected.

[0004] Tin oxide (SnO2) is generally used as the semiconductor layer 244 of such a gas sensor 200. However, the tin oxide semiconductor layer 244 adsorbs any gas molecules, and therefore has low selectivity for the target substance to be detected, making it impossible to accurately detect the presence or concentration of a specific target substance in some cases.

[0005] There are also gas sensors in which an insulating film is formed on the semiconductor layer 244 in order to protect the semiconductor layer 244, but insulating films also have the problem of adsorbing any gas molecules and having low selectivity for the target substance to be detected.

[0006] Furthermore, in such gas sensors, accurate detection is sometimes difficult because the change in the resistance value of the semiconductor layer 244 is small. In such cases, the change in the resistance value of the semiconductor layer 244 can be increased by heating the semiconductor layer 244 to increase the temperature, but this requires a mechanism for heating the semiconductor layer 244 and increases the energy required for measurement.

[0007] In view of the current situation, the present invention aims to provide a device that can be used in a concentration measurement apparatus and a concentration measurement method that can selectively detect a target substance in a test sample and accurately detect the presence or absence and concentration of a specific target substance using small amounts of energy.

[0008] The present invention has been invented to solve the problems in the prior art as described above, and the device of the present invention, a concentration measuring apparatus equipped with the same, and a concentration measuring method using the same include those configured as follows.

[0009] [1] A device having an insulating substrate, at least one insulating composite layer, and a storage section capable of storing an analyte, 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 that ionizes an analyte in the analyte, and an ion capture section that captures the ionized analyte between the insulating composite layer and the storage section.

[0010] [2] The device according to [1], wherein the semiconductor layer is composed 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 tantalum (Ta), strontium (Sr), and niobium (Nb).

[0011] [3] The device according to [1] or [2], wherein the ion-trapping moiety is an ionophore.

[0012] [4] The device according to any one of [1] to [3], wherein the ionization section includes a gas-permeable membrane.

[0013] [5] The device according to any one of [1] to [4], wherein the ionization portion is in a gel state.

[0014] [6] The device according to [1] or [2], wherein the ion-trapping section and the ionization section are made of an ionic liquid.

[0015] [7] The device according to [6], wherein the ionic liquid is contained in a liquid-retaining sheet.

[0016] [8] The device according to [1] or [2], wherein the ionization portion is a solid electrolyte having an electrode catalyst.

[0017] [9] The device according to any one of [1] to [6], wherein the ionization portion is a liquid, and further comprises a third electrode in contact with the liquid.

[0018]

[10] The device according to any one of [1] to [8], further comprising a third electrode formed on the insulating substrate in a state insulated from the insulating composite layer.

[0019]

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

[10] , wherein the Vref is 0.1 V or more.

[0020]

[12] An OFF current between the pair of electrodes of the semiconductor layer is 1×10 -12 A device according to any one of [1] to

[11] , wherein A is equal to or less than A.

[0021]

[13] A concentration measurement apparatus comprising: a device according to any one of [1] to

[12] ; and a control device, wherein the control device has: a voltage application means for applying a voltage between the pair of electrodes; a current measurement means for measuring a current flowing between the pair of electrodes when a voltage is applied by the voltage application means; and a concentration calculation means for calculating the concentration of an analyte in the test specimen based on the inter-electrode current measured by the current measurement means.

[0022]

[14] A device according to [9] or

[10] , comprising: a control device; and a voltage application means for varying a voltage applied between the electrode into which a current flows out of the pair of electrodes and the third electrode; a current measurement means for measuring a current flowing between the pair of electrodes; and a threshold voltage V, which is a voltage value of the third electrode when it is determined whether or not a current flows between the pair of electrodes, based on the voltage value applied by the voltage application means and the current value measured by the current measurement means. th a threshold voltage detection means for detecting a threshold voltage V th and a concentration calculation means for calculating the concentration of the target substance in the test sample based on the above.

[0023]

[15] A concentration measurement method for detecting the concentration of an analyte in a test specimen using the device according to any one of [1] to

[12] , comprising measuring an inter-electrode 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 analyte in the test specimen based on the inter-electrode current.

[0024]

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

[10] , wherein a threshold voltage V is a voltage value of the third electrode when a current flows between the pair of electrodes. th and detects the threshold voltage V th A concentration measurement method for measuring the concentration of an analyte in the specimen based on the above.

[0025] According to the present invention, the analyte in the specimen is ionized by the ionization unit, and can then be captured by an ion capture unit that can selectively capture specific ions such as ionophores and ionic liquids, thereby enabling the analyte in the specimen to be selectively detected.

[0026] FIG. 1 is a schematic diagram illustrating the configuration of a concentration measuring apparatus according to this embodiment. FIG. 2 is a schematic diagram illustrating the configuration of a device used in the concentration measuring apparatus of FIG. 1. FIG. 3 is a schematic diagram illustrating a modified example of a device used in the concentration measuring apparatus shown in FIG. 1. FIG. 4 is a schematic diagram illustrating another modified example of a device used in the concentration measuring apparatus shown in FIG. 1. FIG. 5 is a graph illustrating the results of measuring the concentration of an analyte using the concentration measuring apparatus shown in FIG. 4. FIG. 6 is a schematic diagram illustrating the configuration of another embodiment of the concentration measuring apparatus of the present invention. FIG. 7 is a graph illustrating the results of measuring the concentration of an analyte using the concentration measuring apparatus shown in FIG. 6. FIG. 8 is a schematic front view illustrating a modified example of a device used in the concentration measuring apparatus shown in FIG. 6. FIG. 9 is a schematic side view of the device shown in FIG. 8. FIG. 10 is a schematic diagram illustrating the configuration of a conventional gas sensor.

[0027]

[0023] The present invention will be described in more detail below with reference to the accompanying drawings, in which: Fig. 1 is a schematic diagram illustrating the configuration of a concentration measurement apparatus according to the present embodiment; and Fig. 2 is a schematic diagram illustrating the configuration of a device used in the concentration measurement apparatus of Fig. 1.

[0028] In this embodiment, the "analyte" refers to the object to be detected in the sample, and unless otherwise specified, the state of the object is not limited, and it may be gas, liquid, or solid, as long as it is ionizable.

[0029] In this specification, the term "third electrode" includes a reference electrode and a gate electrode.

[0030] As shown in FIG. 1, the concentration measuring apparatus 50 of this embodiment includes a device 10 having an insulating substrate 12, at least one insulating composite layer 14, and a storage section 16 capable of storing an analyte, and a control device 60.

[0031] The device 10 configured as shown in FIG. 2 may 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 in contact with the pair of electrodes 141 and 142 .

[0034] The storage section 16 is not particularly limited as long as it is configured to be able to store the test specimen, but in this embodiment, as will be described later, it is configured by a partition section 16a that is arranged to surround the ion trapping section 18 so that the ionization section 17 provided within the storage section 16 comes into contact with the ion trapping section 18.

[0035] The storage section 16 includes an ionization section 17 that ionizes the analyte in the sample. The ionization section 17 is not particularly limited as long as it can ionize the analyte, and a solvent such as water can be used. The ionization section 17 may be a liquid solvent, but gelling the solvent prevents the ionization section 17 from leaking from the storage section 16, making the concentration measurement device 50 easier to handle. The ionization section 17 may also be a solid electrolyte with an electrode catalyst. In this configuration, the analyte in the sample is ionized by the electrode catalyst, and the solid electrolyte conducts only specific ions, allowing the ion trapping section 18 to capture only the analyte ions.

[0036] An ion-trapping section 18 is provided between the insulating composite layer 14 and the reservoir 16. The ion-trapping section 18 has selectivity for the target substance to be detected in the specimen. Specifically, it has the property of selectively trapping ions of the target substance to be detected. As such an ion-trapping section 18, for example, an ionophore such as a lithium ionophore, a potassium ionophore, a sodium ionophore, a calcium ionophore, an ammonium ionophore, an ionophore for chloride ions, or a magnesium ionophore can be used.

[0037] The method for manufacturing such an ion-trapping portion 18 is not particularly limited. For example, when an ionophore is used, the ion-trapping portion 18 can be manufactured by the following steps. First, polyvinyl chloride is weighed into a beaker. Here, it is preferable to use polyvinyl chloride with a degree of polymerization of approximately 1050 from the viewpoints of easy handling and smooth application to the insulating composite layer 14.

[0038] Next, tetrahydrofuran is added as a solvent to the beaker, and the mixture is stirred with a stirrer until the polyvinyl chloride is dissolved.

[0039] Once the polyvinyl chloride has dissolved, a plasticizer, an ionophore, an anion scavenger if the analyte is a cation, or a cation scavenger if the analyte is an anion, are added, and the mixture is further stirred with a stirrer.

[0040] Examples of the plasticizer that can be used include 2-nitrophenyl octyl ether (NPOE) and bis(2-ethylhexyl) sebacate. Examples of the anion scavenger that can be used include potassium tetrakis(4-chlorophenyl)borate, and examples of the cation scavenger that can be used include tridodecylmethylammonium chloride (TDDMACl).

[0041] The ionophore can be appropriately selected depending on the ion to be detected. For example, lithium ion (Li + ), dibenzyl-14-crown-4, TTD-14-crown-4, potassium ion (K + ), bis(benzo-15-crown-5), sodium ion (Na + ), bis(12-crown-4), calcium ions (Ca 2+ ) to detect HDOPP-Ca, ammonium ion (NH4 + ), nonactin, chloride ions (Cl - ), Bisthiourea-1, magnesium ions (Mg 2+When it is desired to detect C14-K22B5, K22B1B5, or K22B9, C14-K22B5, K22B1B5, or K22B9 can be used.

[0042] The solution thus prepared is then spread on a glass petri dish and air-dried to form the ion-trapping part 18. From the viewpoint of increasing the response speed (establishment of ion diffusion equilibrium), it is effective to make the ion-trapping part 18 thin, and in this case, it is preferable to form the ion-trapping part 18 by spin coating.

[0043] The ion trapping section 18 thus prepared is cut to an appropriate size and attached to the insulating composite layer 14 so as not to trap air therein, and the storage section 16 is then bonded onto the attached ion trapping section 18 using, for example, epoxy resin, thereby completing the device 10.

[0044] The insulating composite layer 14 includes an insulating film 146 at least at a location in contact with the ion trapping unit 18. The insulating film 146 also serves as a protective layer for protecting the semiconductor layer 144 from the analyte and the ionization unit 17. The insulating film 146 prevents corrosion of the semiconductor layer 144 and improves the durability and reliability of the semiconductor layer 144. Any known insulating material can be used for the insulating film 146, with corrosion resistance being preferred. Examples of insulating materials include Ta2O5, Si3N4, and SiO2, and the thickness is preferably 0.01 μm to 0.5 μm, more preferably 0.03 μm to 0.2 μm.

[0045] The semiconductor layer 144 has a field effect mobility of 20 cm 2 / Vs or more, and particularly 60 cm 2 It is more preferable that the voltage is equal to or higher than / Vs.

[0046] Such a semiconductor layer 144 is composed of an oxide containing indium (In), zinc (Zn), and an additional element (X), and the additional element (X) is at least one element selected from tantalum (Ta), strontium (Sr), and niobium (Nb).

[0047] Specifically, it is preferable that the atomic ratio of In and X satisfy the following formula (1) (X in the formula is the sum of the content ratios of the additive 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)

[0048] When the atomic ratio of In, Zn, and X satisfies the formulas (1) to (3), the semiconductor layer 144 exhibits the field effect mobility and OFF current described above.

[0049] In order for the semiconductor layer 144 to exhibit higher field-effect mobility and lower OFF current, it is more preferable that the atomic ratios of In, Zn, and X satisfy the following formulas (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)

[0050] It is more preferable that the atomic ratios of In, Zn and X satisfy the following formulas (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), and 0.002<X / (In+Zn+X)≦0.012 (3-3).

[0051] It is more preferable that the atomic ratios of In, Zn and X satisfy the following formulas (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)

[0052] It is more preferable that the atomic ratios of In, Zn and X satisfy the formulas (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), and 0.003≦X / (In+Zn+X)≦0.009 (3-5).

[0053] As described above, the additive element (X) is one or more elements selected from Ta, Sr, and Nb. These elements can be used alone or in combination of two or more elements. The additive element (X) may contain elements other than Ta, Sr, and Nb, but preferably contains only these elements.

[0054] Furthermore, the thinner the thickness of the semiconductor layer 144, the greater the change in the conductivity of the surface layer, and therefore the greater the change in the moving charge, as described below, and the improved 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 particular lower limit for the thickness of the semiconductor layer 144, but it is generally 0.005 μm or more.

[0055] Furthermore, it is preferable that the surface 144a of the semiconductor layer 144 facing the ion-trapping unit 18 is as smooth as possible. If the surface 144a of the semiconductor layer 144 is not smooth, gaps may be formed between the insulating film 146 or the insulating film 146 may be discontinuous, reducing the adhesion between the insulating film 146 and the ion-trapping unit 18 and making it impossible to accurately capture potential changes from the ion-trapping unit 18. This may result in reduced measurement accuracy or unstable operation.

[0056] 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 restriction on 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 section 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 restriction on the lower limit of this arithmetic mean height Sa, but it is generally 0.0002 μm or more.

[0057] Here, the maximum height Sz and the arithmetic mean height Sa are parameters of surface roughness defined in ISO 25178, and such parameters can be measured, for example, by a 3D surface roughness profiler (NexView, manufactured by Zygo Corporation). In this case, the measurement conditions are preferably as follows:

[0058] Measurements are made 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 a range 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 profile measuring instrument under the following correction conditions to calculate the maximum height Sz and arithmetic mean height Sa.

[0059] <Correction conditions> -Remove: Form Remove -Filter Type: Spline -Filter: Low Pass -Type: Gaussian Spline Auto

[0060] When the device 10 described above is formed as a FET structure, it can be formed using a method similar to that used for conventionally known FETs, MOSFETs, etc. For example, a conductive metal thin film is formed on the insulating substrate 12 as the first electrode 141 and the second electrode 142 using a sputtering apparatus, and then an oxide thin film having the above-described configuration is formed as the semiconductor layer 144 using a sputtering apparatus. A shadow mask can be used for patterning when forming the first electrode 141 and the second electrode 142 and the semiconductor layer 144.

[0061] The conductive metal used as the first electrode 141 and the second electrode 142 is not particularly limited, but may be, for example, molybdenum (Mo) or tungsten (W), or an alloy of these metals with cerium oxide (CeO), copper (Cu), silver (Ag), or the like.

[0062] Next, a ceramic thin film can be deposited thereon to form the insulating film 146. Specifically, for example, a plasma CVD apparatus such as Samco Corporation's PD-2202L can be used to deposit a SiOx thin film under the following conditions: film formation gas: SiH4 / N2O / N2 mixed gas, film formation pressure: 110 Pa, and substrate temperature: 250°C to 400°C, to form the insulating film 146.

[0063] In addition, the control device 60 of the concentration measuring device 50 of this embodiment is equipped with 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 measurement means) for measuring the current value between the first electrode 141 and the second electrode 142.

[0064] The control device 60 has a computer equipped with a calculation means, a memory means, an input / output means, etc., and is configured to control the applied voltage of the variable voltage source 32 and measure the current value using the ammeter 36 based on a program stored in the memory means.

[0065] Furthermore, the control device 60 further includes an interelectrode current detection means 61. The interelectrode 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 interelectrode current detection means 61 can be realized by a computer incorporated in the control device 60, etc.

[0066] The inter-electrode current detection means 61 detects a predetermined voltage V between the first electrode 141 and the second electrode 142 by the variable voltage source 32. ds With this applied, the ammeter 36 measures the inter-electrode current I flowing between the first electrode 141 and the second electrode 142. ds Detect.

[0067] Here, the predetermined voltage V ds The voltage V is not particularly limited as long as it is large enough to allow a current to flow through the semiconductor layer 144. ds Since it is sufficient to apply a constant voltage to the variable voltage source 32, a constant voltage source can be used instead of the variable voltage source 32.

[0068] The interelectrode current I thus detected ds The magnitude of the inter-electrode current I is correlated with the amount of ions trapped by the ion trapping unit 18, i.e., the concentration of the target substance in the test sample. ds By creating a calibration curve showing the relationship between the inter-electrode current I measured using the concentration measuring device 50 in advance, ds Based on this, the concentration of the target substance can be determined.

[0069] Alternatively, the concentration of the object to be detected and the inter-electrode current I ds By performing machine learning by associating these data with each other and using them as training data, the inter-electrode current I measured using the concentration measuring device 50 can be calculated using artificial intelligence (AI). ds It is also possible to determine the concentration of the target substance based on the above.

[0070] The control device 60 of this embodiment further includes a concentration calculation means 64. The concentration calculation means 64 calculates the inter-electrode current I detected by the inter-electrode current detection means 61. dsThe concentration calculation means 64 can be realized by a computer incorporated in the control device 60, as described above.

[0071] Fig. 3 is a schematic diagram showing a modified example of the device 10 used in the concentration measuring device 50 shown in Fig. 1. This concentration measuring device 50 basically has the same configuration as the concentration measuring device 50 shown in Figs. 1 and 2, so similar components are given the same reference numerals and detailed descriptions thereof will be omitted.

[0072] 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 a desired gas to pass through. Examples of such a gas-permeable membrane 17a include polydimethylsiloxane (PDMS).

[0073] By configuring in this manner, even when the analyte is a gas containing multiple components, the gas-permeable membrane 17a allows only the gas containing the target substance to pass through, thereby improving the selectivity of the target substance and enabling more accurate detection of the presence or absence and concentration of the target substance in the analyte.

[0074] Fig. 4 is a schematic diagram showing another modified example of the device 10 used in the concentration measuring device 50 shown in Fig. 1. This concentration measuring device 50 basically has the same configuration as the concentration measuring device 50 shown in Figs. 1 and 2, so similar components are given the same reference numerals and detailed descriptions thereof will be omitted.

[0075] In the concentration measuring device 50 of this embodiment, the ionization unit 17 and the ion trapping unit 18 are composed of an ionic liquid 19. By providing the ionic liquid 19 in the storage unit 16 in this manner, when an analyte is introduced into the storage unit 16, the analyte in the analyte is ionized by the ionic liquid 19 and the ionized analyte is trapped, so that the concentration of the analyte in the analyte can be measured in the same manner as in the embodiment shown in FIGS.

[0076] The ionic liquid 19 can be appropriately selected depending on the ions to be detected, and examples thereof include [EMIM] and [BF4].

[0077] Although such ionic liquid 19 may remain in liquid form, it can be gelled or contained in a liquid-retaining sheet such as filter paper, which prevents leakage of ionic liquid 19 from storage section 16 and makes handling of concentration measuring device 50 easier.

[0078] Example 1 FIG. 5 is a graph showing the results of measuring the concentration of a specimen using the concentration measuring device 50 shown in FIG.

[0079] In this example, NH3-containing gas and C2H5OH-containing gas were used as the specimens, and the NH3 concentration and C2H5OH concentration were measured between 0 ppm and 1000 ppm. Note that [EMIM][BF4] was used as the ionic liquid 19, and the measurement was performed with NH3 as the detection target.

[0080] As shown in FIG. 5, for the NH3-containing gas, the interelectrode current I ds In contrast, for the C2H5OH-containing gas, even if the C2H5OH concentration changes, the interelectrode current I ds was confirmed to be unchanged.

[0081] From this, the inter-electrode current I ds It was confirmed that by measuring the amount of a specific target substance, it is possible to detect the presence or absence and concentration of the target substance.

[0082] 6 is a schematic diagram illustrating the configuration of another embodiment of the concentration measuring device of the present invention. This concentration measuring device 50 is basically configured similarly to the concentration measuring device 50 shown in FIGS. 1 to 5, and therefore similar components are designated by the same reference numerals and detailed descriptions thereof are omitted.

[0083] In the concentration measuring device 50 of this embodiment, the ionization unit 17 is a liquid, and the device further includes a reference electrode 161 as a third electrode in contact with the liquid ionization unit 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.

[0084] In this embodiment, the control device 60 has a computer equipped with a calculation means, a memory means, an input / output means, etc., and is configured to be able to control the applied voltage of the variable voltage source 32 and the variable voltage source 34, measure current values ​​using the ammeter 36, and measure voltage values ​​using the voltmeter 38, based on a program stored in the memory means.

[0085] The control device 60 further includes a threshold voltage detection means 62. The threshold voltage detection means 62 is configured to control the voltages applied by the variable voltage sources 32 and 34, and to receive the current and voltage values ​​measured by the ammeter 36 and voltmeter 38 as electrical signals. Such threshold voltage detection means 62 can be realized by a computer incorporated in the control device 60, or the like.

[0086] The threshold voltage detection means 62 detects a predetermined voltage V between the first electrode 141 and the second electrode 142 by the variable voltage source 32. ds In this state, the voltage V applied between the first electrode 141 and the reference electrode 161 by the variable voltage source 34 is g Then, the threshold voltage detection means 62 measures the current I flowing between the first electrode 141 and the second electrode 142 using the ammeter 36. d The change in the voltage V between the first electrode 141 and the reference electrode 161 is detected by the voltmeter 38. g By detecting the change in the threshold voltage V th Measure.

[0087] In this case, in the device 10 having the above-described configuration, the semiconductor layer 144 is configured such that the voltage applied to the reference electrode 161 is equal to or lower than the threshold voltage V thWhen the OFF current, which is the current flowing from the first electrode 141 to the second electrode 142 or the current flowing from the second electrode 142 to the first electrode 141, is 1×10 -12 A or less is preferable, and 1 × 10 -14 A or less. Such a small OFF current allows the threshold voltage V th When detecting the threshold voltage V, it is possible to detect the threshold voltage V with higher accuracy even if the voltage applied between the first electrode 141 and the second electrode 142 is small. th can be detected.

[0088] In the device 10 configured as described above, the threshold voltage V th It is known that the threshold voltage V changes depending on the amount of ions to be detected trapped in the ion trapping section 18. th By measuring the concentration of the target substance contained in the test sample, it is possible to detect the concentration of the target substance contained in the test sample.

[0089] The threshold voltage V th The method for measuring the current I is not particularly limited. For example, the current I d The voltage V when g may be detected, or the current I d When the voltage V g Gradually decrease the current I d The voltage V when the current stops flowing g Alternatively, the 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 this is the threshold voltage V th However, from the viewpoint of more accurate measurement, it is possible to use a conventionally known method such as ds is kept constant, and the voltage V g is applied within a predetermined range, and the current I d Measure V in a predetermined range g √I for d The approximate line is calculated using the least squares method, and the √I of the approximate line is calculated. d V when = 0g is the threshold voltage V th It is preferable to set the following.

[0090] The threshold voltage V measured in this way th Since there is a correlation between the concentration of the object to be detected and the threshold voltage V th By creating a calibration curve showing the relationship between the threshold voltage V th Based on this, the concentration of the target substance can be determined.

[0091] Alternatively, the concentration of the object to be detected and the threshold voltage V th By performing machine learning by associating the threshold voltage V measured using the concentration measuring device 50 with the threshold voltage V th It is also possible to determine the concentration of the target substance based on the above.

[0092] The density calculation means 64 of this embodiment calculates the threshold voltage V detected by the threshold voltage detection means 62. th The concentration calculation means 64 can be realized by a computer incorporated in the control device 60, as described above.

[0093] Example 2 FIG. 7 is a graph showing the results of measuring the concentration of a specimen using the concentration measuring device 50 shown in FIG.

[0094] In this example, an NH3-containing gas was used as the analyte, and the NH3 concentration was measured between 0 ppm and 10 ppm. Water was used as the ionization unit 17, and ammonium ionophore was used as the ion trapping unit 18, and the measurement was performed with NH3 as the detection target.

[0095] FIG. 7(a) shows the threshold voltage V detected when the NH3 concentration was 0 ppm to 0.5 ppm. th As a result, FIG. 7B shows the results of the threshold voltage Vth detected when the NH3 concentration was 1 ppm to 10 ppm.

[0096] As shown in FIGS. 7(a) and 7(b), the threshold voltage V thIt was confirmed that the threshold voltage V th It was confirmed that by measuring the amount of a specific target substance, it is possible to detect the presence or absence and concentration of the target substance.

[0097] Fig. 8 is a schematic front view showing a modified example of the device 10 used in the concentration measuring device 50 shown in Fig. 6, and Fig. 9 is a schematic side view of the device 10 shown in Fig. 8. This concentration measuring device 50 basically has the same configuration as the concentration measuring device 50 shown in Figs. 1 to 6, so similar components are given the same reference numerals and detailed descriptions thereof will be omitted.

[0098] 8 and 9 , in the concentration measuring device 50 of this embodiment, 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 between the gate electrode 131 and the insulating composite layer 14.

[0099] 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 in the same manner as the concentration measuring device 50 shown in FIG. g By detecting the change in the threshold voltage V th By measuring the threshold voltage V th Based on this, the concentration of the target substance can be determined.

[0100] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications are possible within the scope of the object of the present invention.

[0101] REFERENCE SIGNS LIST 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 Reservoir 16a Partition 161 Reference electrode 17 Ionization section 17a Gas permeable membrane 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 detecting means 62 Threshold voltage detecting means 64 Concentration calculating means

Claims

1. A device having an insulating substrate, at least one insulating composite layer, and a storage section capable of storing an analyte, 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 that ionizes an analyte in the analyte, and an ion capture section that captures the ionized analyte between the insulating composite layer and the storage section.

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

3. The device of claim 1, wherein the ion-trapping moiety is an ionophore.

4. The device of claim 1, wherein the ionization portion comprises a gas-permeable membrane.

5. The device according to claim 1, wherein the ionization portion is in a gel state.

6. The device according to claim 1, wherein the ion trapping section and the ionization section are made of an ionic liquid.

7. The device according to claim 6, wherein the ionic liquid is contained in a liquid-retaining sheet.

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

9. The device of claim 1, wherein the ionizing portion is a liquid, and further comprising a third electrode in contact with the liquid.

10. The device of claim 1, further comprising a third electrode formed on said insulating substrate insulated from said insulating composite layer.

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

12. The OFF current between the pair of electrodes of the semiconductor layer is 1×10 -12 2. The device of claim 1, wherein the .lambda.

13. A concentration measuring apparatus comprising: a device according to any one of claims 1 to 12; and a control device, wherein the control device has: voltage application means for applying a voltage between the pair of electrodes; current measurement means for measuring a current flowing between the pair of electrodes when a voltage is applied by the voltage application means; and concentration calculation means for calculating the concentration of the target substance in the test sample based on the inter-electrode current measured by the current measurement means.

14. A device according to claim 9 or 10, comprising: a control device; and a voltage application means for varying a voltage applied between the third electrode and one of the pair of electrodes into which a current flows; a current measurement means for measuring a current flowing between the pair of electrodes; and a threshold voltage V, which is a voltage value of the third electrode at which it is determined whether or not a current flows between the pair of electrodes, based on the voltage value applied by the voltage application means and the current value measured by the current measurement means. th a threshold voltage detection means for detecting a threshold voltage V th and a concentration calculation means for calculating the concentration of the target substance in the test sample based on the above.

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

16. A concentration measurement method for detecting the concentration of a target substance in a test specimen using the device according to claim 9 or 10, comprising: a threshold voltage V, which is the voltage value of the third electrode when a current flows between the pair of electrodes and when a current flows between the pair of electrodes and when a current flows between the pair of electrodes, th and detects the threshold voltage V th A concentration measurement method for measuring the concentration of an analyte in the specimen based on the above.

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