Ion sensor and method for detecting target substance

Abstract

An ion sensor (1) is provided with an ion detecting element (3), a reference electrode (5) for providing an electric potential reference point, and a solution (7) having an ion concentration that can be changed in a sensing area (29) of the ion detecting element. The sensing area of the ion detecting element is disposed in the solution. The method for detecting a substance being detected employs the ion sensor. The substance being detected, bound to a marker having a function of changing the amount of ions detectable by the ion sensor, is introduced into the solution, and a change in the amount of ions is detected using the ion sensor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims priority based on Japanese Patent Application No. 2021-151177, filed with the Japan Patent Office on September 16, 2021, and the entire contents of Japanese Patent Application No. 2021-151177 are incorporated by reference into this international application. [Technical field]

[0002] The present disclosure relates to an ion sensor and a method for detecting a substance to be detected. [Background technology]

[0003] An ion sensor includes an ion detection element. An example of an ion sensor is a pH sensor. Known ion detection elements include a pH glass electrode and an ISFET (Ion Sensitive Field Effect Transistor). A pH sensor is disclosed in Non-Patent Document 1. An ISFET is disclosed in Non-Patent Documents 2 and 3. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] BUNSEKI KAGAKU Vol. 69, No. 7-8, pp. 385-397 (2020) [Non-Patent Document 2] Measurement and Control Vol. 25, No.11 (November 1986) [Non-Patent Document 3] Nature Vol. 475, pp. 348-352 Summary of the Invention

[0005] As a result of detailed investigations by the inventors, the following problem was found: When measuring ions in a solution using a conventional ion sensor, the output of the ion sensor drifted and was not stable until a hydration layer was formed on the sensing interface after the ion detection element came into contact with the solution. Therefore, the user had to wait until the output of the ion sensor stabilized after the ion detection element came into contact with the solution.

[0006] In one aspect of the present disclosure, it is preferable to provide an ion sensor and a method for detecting a target substance, which can shorten the time until the output becomes stable.

[0007] One aspect of the present disclosure is an ion sensor comprising an ion detection element, a reference electrode that provides a reference point of electric potential, and a solution in which the ion concentration can be changed in a sensing area of ​​the ion detection element, the sensing area of ​​the ion detection element being disposed in the solution.

[0008] In the ion sensor according to one aspect of the present disclosure, the sensing area of ​​the ion detection element is disposed in a solution. Therefore, the ion detection element is in a state where the output drift has settled. As a result, by using the ion sensor according to one aspect of the present disclosure, the time until the output is stabilized can be shortened.

[0009] Another aspect of the present disclosure is a method for detecting a detectable substance using an ion sensor. The ion sensor includes an ion detection element, a reference electrode that provides a reference point for electric potential, and a solution in which the ion concentration is variable in the sensing area of ​​the ion detection element. In the ion sensor, the sensing area of ​​the ion detection element is disposed in the solution. In the method for detecting a detectable substance, the detectable substance bound to a label having a function of changing the amount of ions detectable by the ion sensor is introduced into the solution, and the ion sensor is used to detect the change in the amount of ions corresponding to the concentration of the label.

[0010] In another aspect of the present disclosure, a method for detecting a substance to be detected uses an ion sensor. In the ion sensor, the sensing area of ​​the ion detection element is disposed in a solution. Therefore, the ion detection element is in a state where the output drift has settled. As a result, in the method for detecting a substance to be detected, which is another aspect of the present disclosure, the time until the output of the ion sensor is stabilized can be shortened. [Brief description of the drawings]

[0011] [Figure 1] 1 is a side cross-sectional view illustrating a configuration of an ion sensor in a first embodiment. [Diagram 2] 2 is a side cross-sectional view illustrating a configuration of a sensor unit and its surroundings in the first embodiment. FIG. [Diagram 3] 11 is a graph showing the results of continuously acquiring the output of the ion sensor from the point in time when the solution was introduced into the container. [Figure 4] 1 is a graph showing the results of continuously detecting the pH of a solution starting immediately after the solution was replaced. [Diagram 5] FIG. 1 is an explanatory diagram showing the metabolism occurring in a solution. [Figure 6] 1 is a graph showing the amount of change in pH of a solution 60 minutes after each sample was added to the solution. [Figure 7] FIG. 7A is a side cross-sectional view showing the configuration of a groove portion, FIG. 7B is a side cross-sectional view showing the configuration of a doubly formed protrusion portion, and FIG. 7C is a side cross-sectional view showing the configuration of a doubly formed groove portion. [Figure 8] FIG. 2 is a cross-sectional view showing a cross section VIII-VIII in FIG. [Figure 9] FIG. 11 is a perspective view illustrating a configuration of an ion sensor according to a second embodiment. [Figure 10] 13 is a plan view of an ion sensor according to a second embodiment, as viewed from a viewpoint PX. FIG. [Figure 11] 13 is a plan view of the ion sensor according to the second embodiment as viewed from a viewpoint PY. FIG. [Figure 12] FIG. 11 is a side cross-sectional view illustrating the configuration of an ion sensor according to a third embodiment. [Figure 13] Figure 13A is a plan view showing the configuration of the groove portion of the sensor portion as seen from the viewpoint PX, Figure 13B is a plan view showing the configuration of the protrusion portion of the doubly formed sensor portion as seen from the viewpoint PX, and Figure 13C is a plan view showing the configuration of the groove portion of the doubly formed sensor portion as seen from the viewpoint PX. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Exemplary embodiments of the present disclosure will now be described with reference to the drawings.

[0013] First Embodiment 1. Configuration of ion sensor 1 The configuration of the ion sensor 1 will be described with reference to Fig. 1, Fig. 2, and Fig. 8. As shown in Fig. 1, the ion sensor 1 includes a sensor unit 3, a reference electrode 5 that provides a reference point for the electric potential, a solution 7, a container 9, ISFET connection terminals 11, 13, and 15, and a reference electrode connection terminal 17.

[0014] The container 9 is composed of a bottom 21, a side portion 23, and a lid 25. The lid 25 is removable. When the lid 25 is attached, the inside of the container 9 is sealed. The bottom 21 is made of, for example, a molded body, a printed circuit board, or the like.

[0015] 1 and 8, the side portion 23 has a cylindrical shape. The bottom portion 21 is attached to one of the two ends of the side portion 23. The lid 25 is attached to the other end opposite to the one of the two ends of the side portion 23. The bottom portion 21 and the lid 25 close the openings at the two ends of the side portion 23.

[0016] The connection points between the side portion 23 and the bottom portion 21 are sealed, for example, by a screw structure, an adhesive such as epoxy, welding using a laser or heat, press fitting, sealing via a gasket such as an O-ring, insert molding, etc. The connection points between the side portion 23 and the lid 25 are sealed, for example, by an elastic material such as rubber, a screw structure, an aluminum pouch, a film, etc.

[0017] As shown by the arrow in Fig. 1, the direction from the bottom 21 toward the lid 25 is the X direction. The direction opposite to the X direction is the Y direction. The ion sensor 1 is usually used in an orientation in which the Y direction coincides with the vertical direction. Of the surfaces of the bottom 21, the surface on the X direction side is the X-side surface 21X. Of the surfaces of the bottom 21, the surface on the Y direction side is the Y-side surface 21Y.

[0018] The bottom 21 includes a recess 21A and a protrusion 21B. In the protrusion 21B, the X-side surface 21X protrudes in the X direction further than the recess 21A. As shown in Fig. 8, when viewed from a viewpoint PX, the recess 21A is located on the center side, and the protrusion 21B is located on the end side. The recess 21A is circular, and the protrusion 21B is annular.

[0019] The sensor unit 3 includes an ISFET. The ISFET corresponds to an ion detection element. The sensor unit 3 is disposed inside the container 9 as shown in FIG. 1. The sensor unit 3 is fixed to the X-side surface 21X by a fixing member 26 in the recess 21A as shown in FIG. 2. The surface of the sensor unit 3 includes an X-side surface 3A, a Y-side surface 3B, and an end surface 3C. The X-side surface 3A is a main surface on the X-direction side. The X-side surface 3A contacts the solution 7. The Y-side surface 3B is a main surface on the Y-direction side. The fixing member 26 contacts the Y-side surface 3B. The end surface 3C is an end surface that constitutes the outer peripheral end of the sensor unit 3 when viewed from the viewpoint PX.

[0020] As shown in FIG. 1, FIG. 2, and FIG. 8, the protective member 27 is attached to the recess 21A. As shown in FIG. 8, the protective member 27 is arranged to surround the sensor unit 3 as viewed from the viewpoint PX. The protective member 27 is in contact with a contact portion 3D, which is a part of the surface of the sensor unit 3. The contact portion 3D includes an end face 3C. The contact portion 3D also includes a portion of the X-side surface 3A that is on the end face 3C side. The contact portion 3D includes an edge between the end face 3C and the surface 3A. However, the contact portion 3D does not include a sensing area 29, which will be described later. The protective member 27 is in contact with the X-side surface 21X around the sensor unit 3. The protective member 27 includes a filler 27A and a dam agent 27B. The dam agent 27B is located on the X-side surface 3A. The dam agent 27B is located closer to the sensing area 29 than the filler 27A. The dam agent 27B inhibits the filling agent 27A from proceeding in the direction of the sensing area 29.

[0021] A plurality of bonding wires 28 are provided inside the protective member 27. The bonding wires 28 are covered by the protective member 27. The protective member 27 is made of an insulating material such as epoxy resin. The protective member 27 has the function of protecting and insulating the bonding wires 28, as well as protecting the end face 3C. The bonding wires 28 electrically connect the ISFET provided in the sensor unit 3 to the ISFET connection terminals 11, 13, and 15.

[0022] A sensing area 29 is provided on the surface 3A on the X side. The sensing area 29 detects ions (hereinafter referred to as target ions) that are the detection target of the ISFET. In this embodiment, the target ions are hydrogen ions. The sensing area 29 is located near the center of the surface 3A on the X side when viewed from the viewpoint PX. The sensing area 29 is not covered by the protective member 27.

[0023] 2, the sensor unit 3 includes a gate insulating film 34 and an aluminum pad 36 on the X-direction side. The surface 3A on the X side is the surface of the gate insulating film 34. The aluminum pad 36 is provided for electrical connection with the bonding wire 28.

[0024] 2, a protrusion 30 is formed on a surface 3A on the X side. When viewed from a viewpoint PX, the shape of the protrusion 30 is annular. The protrusion 30 is disposed so as to surround the periphery of the sensing area 29.

[0025] When viewed from the viewpoint PX, the protective member 27 is located outside the protruding portion 30. A part of the protruding portion 30 is provided in a portion between the sensing area 29 and the protective member 27. The protruding portion 30 protrudes in the X direction compared to the surrounding X-side surface 3A. Therefore, a step 32 is formed between the protruding portion 30 and the surrounding X-side surface 3A.

[0026] The reference electrode 5 is disposed inside the container 9. The reference electrode 5 is attached to the X-side surface 21X of the protrusion 21B. The reference electrode 5 is located on the X-direction side of the sensor unit 3. In other words, the reference electrode 5 is located closer to the lid 25 than the sensor unit 3. The reference electrode 5 is an Ag / AgCl electrode.

[0027] As shown in FIG. 1, the solution 7 is contained in a container 9. The solution 7 is a solution whose ion concentration can change in the sensing area 29. The solution 7 is an aqueous solution containing chloride ions. The chloride ion concentration is 0.01M to 3M. When the chloride ion concentration is 0.01M to 3M, the output fluctuation of the ion sensor 1 can be further suppressed. The output of the ion sensor 1 is, for example, a current value accompanying a change in the potential of the sensing area 29. The chloride ions are ions necessary for the oxidation-reduction reaction of the reference electrode 5. The solution 7 is contained in the container 9, for example, even when the ion sensor 1 is not in use.

[0028] 1, the sensor unit 3 is disposed in the solution 7. Therefore, the sensing area 29 is also disposed in the solution 7. The reference electrode 5 is also disposed in the solution 7. During normal use of the ion sensor 1, the reference electrode 25 is located closer to the liquid surface of the solution 7 than the sensor unit 3.

[0029] The ISFET connection terminals 11, 13, 15 and the reference electrode connection terminal 17 are members made of a conductive material such as metal, etc. The ISFET connection terminals 11, 13, 15 and the reference electrode connection terminal 17 are embedded in the bottom portion 21 by a resin mold.

[0030] The ISFET connection terminal 11 has an electrode portion 11X exposed on a surface 21X on the X side. A bonding wire 28 is connected to the ISFET connection terminal 11 at the electrode portion 11X. The electrode portion 11X is covered with a protective member 27. The ISFET connection terminal 11 also has an electrode portion 11Y exposed on a surface 21Y on the Y side.

[0031] The ISFET connection terminal 13 has an electrode portion 13X exposed on the X-side surface 21X. A bonding wire 28 is connected to the ISFET connection terminal 13 at the electrode portion 13X. The electrode portion 13X is covered with a protective member 27. The ISFET connection terminal 13 also has an electrode portion 13Y exposed on the Y-side surface 21Y.

[0032] The ISFET connection terminal 15 has an electrode portion 15X exposed on a surface 21X on the X side. A bonding wire 28 is connected to the ISFET connection terminal 15 at the electrode portion 15X. The electrode portion 15X is covered with a protective member 27. The ISFET connection terminal 15 also has an electrode portion 15Y exposed on a surface 21Y on the Y side.

[0033] The reference electrode connection terminal 17 is electrically connected to the reference electrode 5. The reference electrode connection terminal 17 includes an electrode portion 17Y exposed on a surface 21Y on the Y side. The electrode portions 11Y, 13Y, 15Y, and 17Y can output a signal of the ion sensor 1 to an external device.

[0034] A part of the inside of the container 9 is occupied by gas. The gas is, for example, an inert gas. The inert gas is, for example, nitrogen.

[0035] The ion sensor 1 can be used, for example, as follows. The lid 25 is removed, and the substance to be detected is added to the solution 7. The internal space of the container 9 is then sealed with the lid 25, and the gas inside the container 9 is replaced with an inert gas. The substance to be detected may be a solid, liquid, or gas. The amount of the target ion in the solution 7 changes as a result of the addition of the substance to be detected.

[0036] For example, the label bound to the substance to be detected causes a reaction that produces or consumes the target ion, and the amount of the target ion in the solution 7 changes. The substance involved in the reaction that produces or consumes the target ion may be included in the solution 7 before the ion sensor 1 is used, or may be added to the solution 7 when the ion sensor 1 is used. When the amount of the target ion changes, the surface potential of the sensing area 29 changes based on the potential provided by the reference electrode 5. This change in surface potential changes the amount of free electrons attracted to the semiconductor surface inside the ISFET. The change in the amount of ions is detected by measuring the current value associated with the change in the amount of free electrons. The ion sensor 1 detects the change in the amount of ions according to the concentration of the label.

[0037] 2. Detection method of target substance The method for detecting a substance to be detected according to the present disclosure uses an ion sensor 1. The ion sensor 1 is the one described above in the section "1. Configuration of ion sensor 1."

[0038] In the method for detecting a substance to be detected, the substance to be detected is introduced into a solution 7. The substance to be detected that is introduced is bound to a label. The label has a function of changing the amount of ions in the solution 7. The ion sensor 1 is capable of detecting the ions.

[0039] The ion sensor 1 is used to detect the change in the amount of ions in the solution 7. The more the detectable substance is introduced into the solution 7, the greater the number of labels and the greater the change in the amount of ions. That is, the change in the amount of ions corresponds to the concentration of the labels. The change in the amount of ions is, for example, proportional to the concentration of the labels. Therefore, the method for detecting the detectable substance can detect the detectable substance based on the change in the amount of ions in the solution 7. The method for detecting the detectable substance can qualitatively determine the presence or absence of the detectable substance. The method for detecting the detectable substance can also quantitatively determine the amount of the detectable substance.

[0040] For example, as shown in Fig. 5, a fusion product 103 is bound to a substance to be detected, such as a virus 101. The fusion product 103 includes a binding substance 105 and a label 107. The binding substance 105 has an activity of binding to the substance to be detected. The label 107 is bound to the substance to be detected via the binding substance 105. Examples of the binding substance 105 include a low molecular weight protein preparation, a nucleic acid aptamer, a monoclonal antibody, and a polyclonal antibody.

[0041] Examples of low molecular weight protein preparations include fragment antibodies, single chain antibodies, diabodies, nanobodies, VHHs, and peptide aptamers.

[0042] The number of bases in the nucleic acid aptamer is, for example, from 10 to 100. When the number of bases is 100 or less, even if the target substance is close to another substance, the fusion product 103 is less susceptible to interference from the other substance and easily binds to the target substance.

[0043] The nucleic acid aptamer may be, for example, a combination of multiple units each made of a nucleic acid. The number of bases in each unit is preferably 10 to 100. When the number of bases in each unit is 100 or less, even if the target substance is close to another substance, the fusion product 103 is less susceptible to interference from the other substance and is more likely to bind to the target substance.

[0044] Examples of the nucleic acid aptamer include DNA aptamers and RNA aptamers. The binding substance 105 can be chemically synthesized, for example, by an in vitro process. The binding substance 105 binds to the substance to be detected, for example, by an intermolecular interaction of the type occurring between an antibody and an antigen. Examples of the bond by the intermolecular interaction of the type occurring between an antibody and an antigen include hydrogen bonds, bonds due to electrostatic complementarity, bonds due to hydrophobic contact, and three-dimensional bonds.

[0045] The label 107 is fused to the binding substance 105. The label 107 has a function of changing the amount of ions detectable by the ion sensor 1. An example of the label 107 is an enzyme. The enzyme has, for example, an activity of inducing metabolism using a substrate as a starting material (hereinafter, referred to as enzyme activity). Examples of the metabolism include metabolism that produces hydrogen ions, metabolism that consumes hydrogen ions, and the like.

[0046] When a metabolism that produces hydrogen ions or a metabolism that consumes hydrogen ions occurs, the hydrogen ion concentration in the solution 7 changes. Examples of enzymes include protoporphyrinogen oxidase, D-arabinose 1-dehydrogenase, 15-hydroxyprostaglandin dehydrogenase, cyclohexane-1,2-diol dehydrogenase, 1,3-propanediol dehydrogenase, uronate dehydrogenase, 2'-dehydrokanamycin reductase, cholesterol oxidase, lactaldehyde dehydrogenase, 2,5-dioxovalerate dehydrogenase, and the like. dehydrogenase, cinnamoyl-CoA reductase, betaine-aldehyde dehydrogenase, arsenate reductase, 2-enoate reductase, fumarate reductase, coproporphyrinogen dehydrogenase, 3-oxosteroid 1-dehydrogenase, 3-oxo-5α-steroid 4-dehydrogenase, alanine dehydrogenase, diaminopimelate dehydrogenasedehydrogenase, alkaline phosphatase, beta-lactamase, carbonyl reductase, shikimate dehydrogenase, D-lactate dehydrogenase, malate dehydrogenase, diacetyl reductase, D-xylose reductase, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, 3alpha-hydroxysteroid 3-dehydrogenase, glycerol-3-phosphate dehydrogenase, chloride peroxidase peroxidase, formate dehydrogenase, ferredoxin-NADP+ reductase, rubredoxin-NAD(P)+ reductase, aspartate-semialdehyde dehydrogenase, aspartate dehydrogenase, aldehyde dehydrogenase, glutamate dehydrogenase, nicotinamide adenine dinucleotide phosphate-hemoprotein reductase, nicotinamide adenine dinucleotide phosphate-dehydrogenase (NAD(P)Hdehydrogenase, dihydrolipoyl dehydrogenase, thioredoxin-disulfide reductase, sulfite dehydrogenase, carbonic anhydrase, glucokinase, and peroxidase.

[0047] For example, label 107 and binding substance 105 each have a chemical substituent. For example, label 107 is fused to binding substance 105 by binding between the chemical substituent of label 107 and the chemical substituent of binding substance 105.

[0048] Examples of the chemical substituent of the label 107 include avidin, streptavidin, neutravidin, N-hydroxysuccinimide, azide, alkyne, dibenzocyclooctyne, bicyclononyne, 2'-O-propargyl, 2'-O-propargyl, thiol, and maleimide.

[0049] Chemical substituents of binding agent 105 include, for example, biotin, primary amine, azide, alkyne, dibenzocyclooctyne, bicyclononyne, 2'-O-propargyl, 2'-O-propargyl, thiol, and the like.

[0050] Examples of substances to be detected include proteins, sugars, lipids, antigens, cells, and viruses. Examples of antigens include antigens presented by cells or viruses, or antigens contained in cells or viruses. Examples of antigens presented by cells or viruses or antigens contained in cells or viruses include the RBD region (hereinafter referred to as RBD) of the novel coronavirus SARS-CoV-2. Examples of viruses include the novel coronavirus SARS-CoV-2.

[0051] 3. Effects of the ion sensor 1 and the method for detecting a target substance (1A) The sensing area 29 is placed in the solution 7. Therefore, the ISFET is in a state where the output drift has settled. As a result, by using the ion sensor 1, the time until the output stabilizes can be shortened. It is presumed that the reason why the ISFET output drift settles down is that when the sensing area 29 is placed in the solution 7, a hydration layer is formed between the surface of the sensing area 29 and the solution 7, and sodium ions permeate into the sensing area 29.

[0052] Furthermore, the reference electrode 5 is placed in the solution 7. Therefore, the reference electrode 5 is in a state where the output drift has settled. As a result, by using the ion sensor 1, the time until the output stabilizes can be shortened.

[0053] In order to confirm the above-mentioned effect, the following test was carried out. First, the ion sensor 1 was prepared with no solution 7 in the container 9. Next, the solution 7 was introduced into the container 9. From the point in time when the solution 7 was introduced, the output of the ion sensor 1 was continuously acquired.

[0054] The output of the ion sensor 1 was as shown in Fig. 3. Immediately after the solution 7 was introduced into the container 9, the output drift was large, and as time passed, the output drift became smaller. During normal use, the ion sensor 1 is in an immersed state in which the sensing area 29 and the reference electrode 5 are immersed in the solution 7. The output drift of the ion sensor 1 in this immersed state is expected to be small and stable, for example, like the output drift at 300 minutes shown in Fig. 3.

[0055] (1B) When the ion sensor 1 is stored, the sensing area 29 and the reference electrode 5 are placed in the solution 7. Therefore, the contaminants that adhere to the sensing area 29 are limited compared to when the sensing area 29 is exposed to the atmosphere. As a result, it is possible to predict the characteristic fluctuation of the ion sensor 1 caused by the adhesion of contaminants.

[0056] (1C) A conventional reference electrode includes an Ag / AgCl electrode, a glass container that houses the electrode, and a KCl solution that fills the glass container. The glass container includes a liquid junction. The liquid junction is a part that electrically connects the solution to be detected with the KCl solution in the glass container. When a conventional reference electrode is used, the KCl solution may pass through the liquid junction and seep into solution 7. In that case, the salt concentration of solution 7 changes, and the detection accuracy of the ion sensor 1 decreases.

[0057] In the ion sensor 1, the solution 7 contains chloride ions. Therefore, the reference electrode 5 does not need to include a glass container and a KCl solution filling the glass container. As a result, the above-mentioned problem of the KCl solution seeping out can be suppressed.

[0058] (1D) The container 9 is sealed. Therefore, even if the ion sensor 1 is stored for a long period of time, CO2 and the like in the atmosphere can be prevented from dissolving into the solution 7. As a result, the pH fluctuation in the solution 7 can be suppressed.

[0059] The following tests were conducted to confirm the above effects. In Test Example 1, the solution 7 in the ion sensor 1 was replaced. Immediately after replacing the solution 7, the lid 25 was closed and the space in the container 9 was purged with nitrogen gas. In Test Example 2, the solution 7 in the ion sensor 1 was replaced. In Test Example 2, after replacing the solution 7, the lid 25 was left unattached. In each of Test Examples 1 and 2, the pH of the solution 7 was continuously detected using the ion sensor 1 immediately after replacing the solution 7. The detection results were as shown in FIG. 4.

[0060] In Test Example 1, the change in pH was small. This was because closing the lid 25 and purging the space inside the container 9 with nitrogen gas prevented CO2 and other gases in the atmosphere from dissolving into the solution 7. In Test Example 2, the change in pH was large. This was because the lid 25 was open, allowing a large amount of CO2 and other gases in the atmosphere to dissolve into the solution 7.

[0061] (1E) The resin contained in the protective member 27 may cause bleeding. The ion sensor 1 includes a protrusion 30. The protrusion 30 changes the direction of the bleed. Furthermore, the presence of the protrusion 30 lengthens the path from the resin to the sensing area 29. Therefore, even if the protective member 27 causes bleeding, the protrusion 30 prevents the bleed from reaching the sensing area 29. As a result, it is possible to prevent the detection accuracy of the ion sensor 1 from being reduced due to the bleeding.

[0062] (1F) The method for detecting a substance to be detected uses the ion sensor 1. Therefore, it is possible to obtain the effects (1A) to (1E) described above.

[0063] 4. reference example (4-1) Synthesis of fusion product 103 A DNA aptamer having the base sequence of SEQ ID NO: 1 (hereinafter referred to as unmodified DNA aptamer) was chemically synthesized by an in vitro process. The base sequence of the unmodified DNA aptamer was "5'-CAGCACCGAC CTTGTGCTTT GGGAGTGCTG GTCCAAGGGC GTTAATGGAC A-3'". The unmodified DNA aptamer is described in Anal. Chem. 2020, 92, 9895-9900 (hereinafter referred to as Reference 1).

[0064] According to the description in Reference 1, the unmodified DNA aptamer is a DNA aptamer that detects the RBD in the spike glycoprotein of the novel coronavirus SARS-CoV-2. Next, the 5' end of the unmodified DNA aptamer was chemically modified with biotin via a C6 spacer.

[0065] The above steps yielded a DNA aptamer. The DNA aptamer corresponds to the binding substance 105. The DNA aptamer was dissolved in a phosphate buffer (hereinafter referred to as 1xPBS / T) to produce a DNA aptamer solution. The concentration of the DNA aptamer in the DNA aptamer solution was 10 μmol / l.

[0066] 1xPBS / T contained 0.05% (v / v) of the surfactant Tween 20. 1xPBS / T also contained 137 mmol / l NaCl, 8.1 mmol / l Na2HPO4, 2.7 mmol / l KCl, and 1.47 mmol / l KH2PO4.

[0067] A streptavidin-alkaline phosphatase conjugate (Thermofisher Scientific, product number S921) was prepared as the label 107. This label 107 is an enzyme. The streptavidin-alkaline phosphatase conjugate is obtained by modifying alkaline phosphatase with streptavidin. Streptavidin is a chemical substituent that modifies the label 107. The label 107 was dissolved in 1xPBS / T to prepare a label solution. The concentration of the label 107 in the label solution was 20 μmol / l.

[0068] 100 μL of the DNA aptamer solution and 5 μL of the label solution were mixed and left to stand at room temperature for 1 hour. During this time, the DNA aptamer and label 107 were fused due to biotin-streptavidin interaction, and fusion 103 was synthesized.

[0069] Next, the fusion product 103 was purified and collected. Specifically, the DNA aptamer that was not fused to the label 107 was separated from the fusion product 103 using an ultrafiltration filter, and the fusion product 103 was collected.

[0070] The binding substance 105 may be a binding substance 105 other than the DNA aptamer. The binding substance 105 may be, for example, a low molecular weight protein preparation, an RNA aptamer, a monoclonal antibody, or a polyclonal antibody. Examples of low molecular weight protein preparations include fragment antibodies, single-chain antibodies, diabodies, nanobodies, VHHs, and peptide aptamers.

[0071] Furthermore, the base sequence of the DNA aptamer may be a base sequence other than the base sequence of SEQ ID NO: 1. The base sequence of the DNA aptamer can be selected depending on the substance to be detected that is to be analyzed. Furthermore, the fusion between the binding substance 105 and the label 107 may be a fusion other than that based on the biotin-streptavidin interaction. Furthermore, when a nucleic acid aptamer is used as the binding substance 105, an end of the nucleic acid aptamer other than the 5' end may be fused to the label 107.

[0072] Furthermore, when a low molecular weight protein preparation is used as binding substance 105, the N-terminus of the low molecular weight protein preparation may be fused to label 107, or the C-terminus may be fused to label 107. When a monoclonal antibody or a polyclonal antibody is used as binding substance 105, the N-terminus of the monoclonal antibody or the polyclonal antibody may be fused to label 107, or the C-terminus may be fused to label 107, as long as the binding ability to the analyte is not lost by fusion with label 107.

[0073] (4-2) Implementation of the detection method for the target substance The novel coronavirus SARS-CoV-2 (hereafter referred to as SARS-CoV-2) was prepared as the substance to be detected. Eight types of suspensions were produced by suspending SARS-CoV-2 in 1xPBS / T. The eight types of suspensions differ only in the number of copies of SARS-CoV-2 contained in the suspension. The copy numbers of SARS-CoV-2 in the eight types of suspensions were 0, 10 to the power of 1, 40, 10 to the power of 2, 10 to the power of 3, 10 to the power of 4, 10 to the power of 5, and 10 to the power of 6 per μL of suspension, respectively, in quantitative PCR conversion. The following process was performed for each of the eight types of suspensions.

[0074] Next, 25 μL of the fusion product solution was dropped into 25 μL of the suspension, and the suspension was allowed to stand at room temperature for 10 minutes. The fusion product solution was a solution containing the fusion product 103 synthesized in the above "(4-1) Synthesis of fusion product 103". The concentration of the fusion product 103 in the fusion product solution was 10 nmol / l. At this time, a part of the fusion product 103 was bound to the detection target substance.

[0075] Next, the entire suspension after standing was dropped onto a Nanosep centrifugal filtration device with a molecular weight cutoff of 300K (PALL, product number OD300C34) and subjected to high-speed centrifugation. By high-speed centrifugation, the fusion product 103 bound to the target substance was collected, and the fusion product 103 not bound to the target substance was separated.

[0076] Next, the Nanosep centrifugal filter device with a molecular weight cutoff of 300K was washed three times with 1xPBS / T, at which time the fusion product 103 that was not bound to SARS-CoV-2 was removed. Next, pNPP was dissolved in solution 7 of ion sensor 1. The concentration of pNPP in solution 7 was 10 mmol / l.

[0077] Next, solution 7 was added to the Nanosep centrifugal filtration device with a molecular weight cutoff of 300K. At this time, as shown in Figure 5, the enzyme activity of alkaline phosphatase in solution 7 induced metabolism using pNPP as substrate 121, and a phosphate group was separated from pNPP. As a result, product 123 was generated. Product 123 was inorganic phosphate and p-nitrophenol.

[0078] The label 107 containing alkaline phosphatase is fused to the binding substance 105 to form a fusion product 103. The fusion product 103 is bound to the virus 101. The virus 101 is SARS-CoV-2.

[0079] The absorption maximum wavelength of p-nitrophenol is 405 nm. Therefore, solution 7 containing p-nitrophenol turned yellow. In addition, the inorganic phosphoric acid produced was ionized in solution 7 and released hydrogen ions. As a result, the pH of solution 7 decreased.

[0080] The pH of solution 7 was continuously recorded. Figure 6 shows the change in pH 60 minutes after solution 7 was added to the Nanosep centrifugal filtration device with a molecular weight cutoff of 300K (hereinafter referred to as the initial time). The change in pH is the amount of change from the pH at the initial time.

[0081] As shown in Figure 6, the higher the copy number of SARS-CoV-2 in the suspension, the greater the change in pH. The change in pH refers to the change in pH relative to the blank. The pH record results show the following: The DNA aptamer in the fusion product 103 had binding activity to SARS-CoV-2 even when fused with the label 107. The alkaline phosphatase in the fusion product 103 had enzyme activity to induce metabolism using pNPP as a substrate even when fused with the DNA aptamer. In addition, inorganic phosphate generated by metabolism using pNPP as a substrate was ionized in the solution and released hydrogen ions. As a result, the pH of the solution 7 decreased. In addition, when the copy number of SARS-CoV-2 in the suspension was 10 to the power of 3 or more, the amount of change in pH was even greater.

[0082] In addition, in order to remove the fusion product 103 that has not bound to the target substance, a centrifugal filtration device other than the Nanosep centrifugal filtration device with a molecular weight cutoff of 300 K may be used. The centrifugal filtration device has, for example, a molecular weight cutoff value equivalent to that of the Nanosep centrifugal filtration device with a molecular weight cutoff of 300 K.

[0083] The method for removing the fusion product 103 that has not bound to the target substance may be a method other than centrifugal filtration. Examples of the method for removing the fusion product 103 that has not bound to the target substance include a sandwich-type removal method using an ELISA plate or magnetic beads, a removal method by filtration chromatography using filter paper or gel, and a removal method by affinity chromatography in which an antibody is supported on a carrier such as gel.

[0084] <Second embodiment> 1. Differences from the first embodiment The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configuration, and the preceding description will be referred to.

[0085] The ion sensor 1 of the second embodiment has a configuration shown in Figures 9 to 11. Note that in Figure 9, the solution 7, the lid 25, and the protective member 27 are omitted.

[0086] The bottom 21 is a printed circuit board. The bottom 21 does not include the recess 21A or the protrusion 21B, and the surface 21X on the X side is flat. In a cross section perpendicular to the X direction, the cross-sectional shape of the bottom 21 is oval.

[0087] The sensor unit 3 is fixed by adhesive in the center of the surface 21X on the X side. The sensor unit 3 includes an ISFET and a temperature sensor. The bottom portion 21 corresponds to a base material on which the sensor unit 3 is attached.

[0088] FIG. 10 is a plan view of the ion sensor 1 as viewed from a viewpoint PX. As shown in FIG. 10, electrode portions 111X, 113X, 115X, and 116X are formed on a surface 21X on the side in the X direction. The electrode portions 111X, 113X, 115X, and 116X are each a thin metal film. The electrode portions 111X, 113X, 115X, and 116X are each rectangular in shape. The electrode portions 111X, 113X, and 115X are each electrically connected to an ISFET provided in the sensor unit 3 by a bonding wire 28. The electrode portion 116X is electrically connected to a temperature sensor provided in the sensor unit 3 by a bonding wire 28.

[0089] As shown in FIG. 10, the reference electrode 5 is formed on the surface 21X on the X side. The reference electrode 5 is an AgCl film. The silver chloride film corresponds to a metal film. The reference electrode 5 has a rectangular shape. As shown in FIG. 9 and FIG. 10, the electrode units 111X, 113X, 115X, and 116X are arranged on one side with the sensor unit 3 as a reference, as viewed from the viewpoint PX. The reference electrode 5 is provided on the opposite side to the electrode units 111X, 113X, 115X, and 116X with the sensor unit 3 as a reference. The sensor unit 3 is located between the electrode units 111X, 113X, 115X, and 116X and the reference electrode 5. The reference electrode 5 has a larger planar size viewed from the viewpoint PX than the electrode units 111X, 113X, 115X, and 116X.

[0090] In the X-side surface 21X, a protrusion 130 is formed between the sensor unit 3 and the electrode units 111X, 113X, 115X, and 116X. When viewed from the viewpoint PX, the shape of the protrusion 130 is a straight line. The protrusion 130 crosses imaginary straight lines connecting the electrode units 111X, 113X, 115X, and 116X to the sensor unit 3. The protrusion 130 protrudes in the X direction compared to the surrounding X-side surface 21X. Therefore, a step is formed between the protrusion 130 and the surrounding X-side surface 21X.

[0091] Fig. 11 is a plan view of the ion sensor 1 as viewed from a viewpoint PY. As shown in Fig. 11, electrode portions 111Y, 113Y, 115Y, 116Y, and 117Y are formed on a surface 21Y on the Y side. The electrode portions 111Y, 113Y, 115Y, 116Y, and 117Y are each a thin metal film.

[0092] The bottom portion 21 includes through holes 211, 213, 215, 216, and 217. When viewed from the viewpoint PX, the through hole 211 is located so as to overlap a part of the electrode portion 111X. The electrode portion 111X is electrically connected to the electrode portion 111Y via the through hole 211.

[0093] When viewed from the viewpoint PX, the through hole 213 is located at a position overlapping a part of the electrode portion 113X. The electrode portion 113X is electrically connected to the electrode portion 113Y by the through hole 213.

[0094] When viewed from the viewpoint PX, the through hole 215 is located at a position overlapping a part of the electrode portion 115X. The electrode portion 115X is electrically connected to the electrode portion 115Y by the through hole 215.

[0095] When viewed from viewpoint PX, through-hole 216 is located at a position overlapping a part of electrode portion 116X. Electrode portion 116X is electrically connected to electrode portion 116Y via through-hole 216.

[0096] When viewed from the viewpoint PX, the through-hole 217 is located at a position overlapping a part of the reference electrode 5. The reference electrode 5 is electrically connected to the electrode portion 117Y by the through-hole 217. The electrode portions 111Y, 113Y, 115Y, 116Y, and 117Y can output a signal of the ion sensor 1 to an external device.

[0097] 10, on the surface 21X on the X side, the protective member 27 is disposed so as to surround the sensor unit 3. The protective member 27 covers the protrusion 130, the bonding wire 28, the electrode units 111X, 113X, 115X, 116X, and the through holes 211, 213, 215, 216, 217. The protective member 27 covers a part of the reference electrode 5 including the connection part with the through hole 217, and does not cover other parts of the reference electrode 5. The protective member 27 also fills the hollows of the through holes 211, 213, 215, 216, 217.

[0098] 2. Effects of the ion sensor 1 and the method for detecting a target substance According to the second embodiment described above in detail, in addition to the effects (1A) to (1F) of the first embodiment described above, the following effect is also obtained.

[0099] (2A) The adhesive for fixing the sensor unit 3 may cause bleeding. The ion sensor 1 includes a protrusion 130 between the sensor unit 3 and the electrode units 111X, 113X, 115X, and 116X. The protrusion 130 changes the direction of bleeding. In addition, the presence of the protrusion 130 lengthens the path from the adhesive to the electrode units 111X, 113X, 115X, and 116X. Therefore, even if the adhesive causes bleeding, the protrusion 130 suppresses the bleeding from reaching the electrode units 111X, 113X, 115X, and 116X. As a result, the deterioration of the electrode units 111X, 113X, 115X, and 116X due to bleeding is suppressed. At the same time, the occurrence of defects in the bonding between the electrode units 111X, 113X, 115X, and 116X and the bonding wires 28 is suppressed.

[0100] The reference electrode 5 is larger than the electrode portions 111X, 113X, 115X, and 116X. Therefore, even if the bleed reaches the reference electrode 5, the influence of the bleed on the reference electrode 5 is small. Therefore, the protrusion 130 does not need to be provided between the sensor portion 3 and the reference electrode 5. When the protrusion 130 is not provided between the sensor portion 3 and the reference electrode 5, the structure of the ion sensor 1 can be simplified.

[0101] (2B) The protective member 27 fills the hollows of the through-holes 211, 213, 215, 216, and 217. Therefore, leakage of the solution 7 from the through-holes 211, 213, 215, 216, and 217 can be suppressed.

[0102] (2C) The sensor unit 3 includes a temperature sensor. Therefore, the ion sensor 1 can detect the temperature of the solution 7.

[0103] <Third embodiment> 1. Differences from the first embodiment The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

[0104] The ion sensor 1 of the third embodiment has a configuration shown in Fig. 12. The container 9 includes a main body 301 and a lid 303. The main body 301 has a bottomed cylindrical shape including a bottom 305. The main body 301 has an opening 307 on the opposite side to the bottom 305. The direction from the bottom 305 toward the opening 307 is defined as the X direction. The direction opposite to the X direction is defined as the Y direction.

[0105] The lid 303 is a cylindrical member made of an elastic body such as rubber. The lid 303 is inserted into the opening 307. The opening 307 is closed by the lid 303. The lid 303 has a cut 309 formed therein. The cut 309 penetrates the lid 303 in the thickness direction of the lid 303. The solution 7 is contained in the container 9.

[0106] The ion sensor 1 includes an insert member 311. The insert member 311 includes a substrate 313, a sensor portion 3, a reference electrode 5, electrode portions 111, 113, 115, and 116, a protruding portion 130, a bonding wire 28, and a protective member 27.

[0107] The substrate 313 is made of a printed circuit board. The basic form of the substrate 313 is a strip extending along the X and Y directions. The substrate 313 has an X-side end 313X on the X-direction side, which is wider than the other portions. The portion of the substrate 313 excluding the X-side end 313X passes through the notch 309 and is inserted into the container 9.

[0108] The sensor unit 3, the reference electrode 5, the electrode units 111, 113, 115, 116, the protrusion 130, the bonding wire 28, and the protective member 27 are provided near the end of the substrate 313 on the bottom 305 side. The sensor unit 3, the reference electrode 5, the protrusion 130, the bonding wire 28, and the protective member 27 in the third embodiment are similar to those in the second embodiment. Also, the electrode units 111, 113, 115, 116 in the third embodiment are similar to the electrode units 111X, 113X, 115X, 116X in the second embodiment.

[0109] The sensor portion 3, the reference electrode 5, the electrode portions 111, 113, 115, 116, the protruding portion 130, the bonding wire 28, and the protective member 27 are disposed in the solution 7. Electrode portions 411, 413, 415, 416, 417, and 418 are formed on the surface of the X-side end portion 313X. Each of the electrode portions 411, 413, 415, 416, 417, and 418 is a thin metal film. Each of the electrode portions 411, 413, 415, 416, 417, and 418 has a rectangular shape.

[0110] Inner layer wirings 511, 513, 515, 516, and 517 are provided inside the substrate 313. The inner layer wirings 511, 513, 515, 516, and 517 are wirings that pass through the inside of the substrate 313.

[0111] Electrode portion 411 is electrically connected to electrode portion 111 via inner layer wiring 511. Electrode portion 413 is electrically connected to electrode portion 113 via inner layer wiring 513. Electrode portion 415 is electrically connected to electrode portion 115 via inner layer wiring 515. Electrode portion 416 is electrically connected to electrode portion 116 via inner layer wiring 516, and electrode portion 417 is electrically connected to reference electrode 5 via inner layer wiring 517.

[0112] The electrode sections 411, 413, 415, 416, and 417 can output a signal from the ion sensor 1 to an external device.

[0113] 2. Effects of the ion sensor 1 and the method for detecting a target substance According to the third embodiment described above in detail, the effects (1A) to (1F) of the first embodiment and the effects (2A) to (2C) of the second embodiment are achieved.

[0114] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0115] (5-1) The ion sensor 1 may be a sensor that detects target ions other than hydrogen ions. In this case, the above-mentioned effects (1A) to (1F) and (2A) to (2C) can be obtained. For example, the material of the sensitive film of the ISFET can be a sensitive film corresponding to the target ions to be detected.

[0116] (5-2) The reference electrode 5 may be an electrode other than an Ag / AgCl electrode. The reference electrode 5 may be, for example, a hydrogen electrode, a calomel electrode, etc. In this case, the above effects (1A) to (1F) and (2A) to (2C) can also be obtained.

[0117] (5-3) The container 9 may not be sealed. For example, an inert gas may be continuously introduced into the container 9 by a gas introduction unit, and the inside of the container 9 may be filled with an inert gas atmosphere. In this case, the above effects (1A) to (1F) and (2A) to (2C) can be obtained. The gas introduction unit can be constructed using a known pump or the like.

[0118] (5-4) The solution 7 does not need to contain chloride ions. The reference electrode 5 may be a conventional Ag / AgCl electrode. In this case, the above-mentioned effects (1A) to (1B), (1D) to (1F), and (2A) to (2C) can be obtained.

[0119] (5-5) The inert gas introduced into the container 9 may be a gas other than nitrogen gas. Examples of the gas other than nitrogen gas include argon gas.

[0120] (5-6) The label 107 may be something other than an enzyme.

[0121] (5-7) As shown in FIG. 7A and FIG. 13A, a groove 33 may be formed instead of the protrusion 30. The groove 33 is formed on the X-side surface 3A. As shown in FIG. 13A, when viewed from the viewpoint PX, the groove 33 is disposed so as to surround the periphery of the sensing area 29. When viewed from the viewpoint PX, the protective member 27 is located outside the groove 33. A part of the groove 33 is provided in a portion between the sensing area 29 and the protective member 27. The groove 33 has a recessed shape compared to the surrounding X-side surface 3A. Therefore, a step 32 is formed between the groove 33 and the surrounding X-side surface 3A.

[0122] Even when the groove 33 is provided instead of the protrusion 30, the above effect (1E) can be achieved. As shown in Figures 7B and 13B, the protrusion 30 may be formed in two layers. In this case, the effect of (1E) above is even more pronounced. As shown in Figures 7C and 13C, the groove 33 may be formed in two layers. In this case, the effect of (1E) above is even more pronounced. Note that the viewpoint PX shown in Figure 7A is omitted in each of Figures 7B and 7C.

[0123] Moreover, a groove may be formed instead of the protrusion 130. Moreover, the protrusion 130 may be formed in two layers, or the groove may be formed in two layers.

[0124] (5-8) The sensor unit 3 may include a sensor other than an ISFET. Examples of sensors other than an ISFET include a pH glass electrode.

[0125] (5-9) The substance to be detected may be a virus other than SARS-CoV-2, a cell, or a molecule such as a protein.

[0126] (5-10) The mounting of the ion sensor 1 is not limited to wire bonding. The mounting of the ion sensor 1 may be, for example, a combination of a flip chip and an underfill agent. The mounting of the ion sensor 1 may also be WLP (Wafer level Packaging). The signal communication is also not limited to wired. The signal communication may be, for example, wireless communication such as NFC (Near field communication).

[0127] (5-11) A plurality of ion sensors 1 may be combined to form an ion sensor system.

[0128] (5-12) The sensor unit 3 may be a chip on which a plurality of sensors are arranged. The plurality of sensors may include, for example, a temperature sensor.

[0129] (5-13) The ion sensor 1 may include a sensor separate from the sensor unit 3 in the solution 7.

[0130] (5-14) The sensor portion 3 and / or the reference electrode 5 may be stored in the solution 7, then dried, and then reused.

[0131] (5-15) The ion sensor 1 may further include a signal processing circuit. The signal processing circuit and the sensor unit 3 can be integrated together.

[0132] (5-16) The ion sensor 1 may estimate or correct the drift signal of the sensor unit 3 by signal processing.

[0133] (5-17) The ion sensor 1 may include, in place of the inert gas, a substance that is insoluble in the solution 7 in the container 9. An example of the substance that is insoluble in the solution 7 is oil.

[0134] (5-18) A pretreatment is a treatment carried out before the detection target substance is introduced into the solution 7. An example of the pretreatment is a treatment for binding the fusion product 103 to the detection target substance. The pretreatment can be carried out, for example, by pipetting by a human, automated treatment by a robot, treatment using a microchannel, or the like.

[0135] (5-19) Multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, part of the configuration of the above embodiments may be omitted. Also, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0136] (5-20) In addition to the above-described ion sensor 1, the present disclosure can be realized in various forms, such as a system including the ion sensor 1 as a component. [Technical idea disclosed in this specification] [Item 1] An ion detection element (3); A reference electrode (5) that provides a reference point for the electric potential; a solution (7) in which the ion concentration is variable in a sensing area (29) of the ion detection element; Equipped with The sensing area of ​​the ion detection element is disposed in the solution. Ion sensor (1). [Item 2] The ion sensor according to item 1, and further comprising at least a portion of the reference electrode disposed in the solution. Ion sensor. [Item 3] Item 3. The ion sensor according to item 1 or 2, The solution contains ions necessary for the redox reaction of the reference electrode. Ion sensor. [Item 4] The ion sensor according to any one of items 1 to 3, a resin (27) that contacts contact portions (3A, 3C) that are portions of the surface of the ion detection element away from the sensing area; a step (32) provided in a portion of the surface between the sensing area and the contact portion; Further comprising: Ion sensor. [Item 5] An ion sensor according to any one of items 1 to 4, a substrate to which the ion detection element is attached by an adhesive; an electrode portion provided on a surface of the base material and electrically connected to the ion detection element; a step (130) provided on a surface of the base material in a portion between the ion detection element and the electrode portion; Further comprising: Ion sensor. [Item 6] Item 6. The ion sensor according to item 5, The reference electrode is provided on a surface of the substrate, The ion detection element is located between the reference electrode and the electrode portion, The reference electrode is larger than the electrode portion. Ion sensor. [Item 7] An ion sensor according to any one of items 1 to 6, Further comprising a container (9) for containing the solution, The container is sealed. Ion sensor. [Item 8] Item 7: The ion sensor according to item 7, containing an inert gas in the container; Ion sensor. [Item 9] A method for detecting a target substance (101) using an ion sensor (1), comprising the steps of: The ion sensor includes: An ion detection element (3); A reference electrode (5) that provides a reference point for the electric potential; A solution (7) in which the ion concentration is variable in the sensing area (29) of the ion detection element, The sensing area of ​​the ion detection element is disposed in the solution; introducing into the solution the substance to be detected that is bound to a label (107) having a function of changing the amount of ions detectable by the ion sensor; detecting a change in the amount of ions according to the concentration of the label using the ion sensor; A method for detecting a substance to be detected.

Claims

1. An ion sensor (1) for detecting a substance to be detected (101), comprising: An ion detection element (3); A reference electrode (5) that provides a reference point for the electric potential; A solution (7) in which the ion concentration is variable in a sensing area (29) of the ion detection element; a container (9) for containing the solution and having an opening for introducing the detection target substance bound to a label (107) having a function of changing the amount of ions detectable by the ion sensor into the solution; Equipped with The sensing area (29) of the ion detection element and at least a portion of the reference electrode are disposed in the solution; The solution contains ions necessary for the redox reaction of the reference electrode. Ion sensor.

2. 2. The ion sensor according to claim 1, a resin (27) that contacts a contact portion (3A, 3C) that is a portion of the surface of the ion detection element away from the sensing area; A step (32) provided in a portion of the surface between the sensing area and the contact portion; Further comprising: Ion sensor.

3. 2. The ion sensor according to claim 1, a substrate to which the ion detection element is attached by an adhesive; an electrode portion provided on a surface of the base material and electrically connected to the ion detection element; A step (130) provided in a portion of the surface of the base material between the ion detection element and the electrode portion; Further comprising: Ion sensor.

4. The ion sensor according to claim 3, The reference electrode is provided on a surface of the substrate, The ion detection element is located between the reference electrode and the electrode portion, The reference electrode is larger than the electrode portion. Ion sensor.

5. 2. The ion sensor according to claim 1, Further comprising a lid for closing the opening. Ion sensor.

6. The ion sensor according to claim 5, containing an inert gas in the container; Ion sensor.

7. A method for detecting a target substance (101) using an ion sensor (1), comprising the steps of: The ion sensor includes: An ion detection element (3); A reference electrode (5) that provides a reference point for the electric potential; A solution (7) in which the ion concentration is variable in the sensing area (29) of the ion detection element, The sensing area (29) of the ion detection element is placed in the solution, and then the detection target substance bound to a label (107) having a function of changing the amount of ions detectable by the ion sensor is introduced into the solution; detecting a change in the amount of ions according to the concentration of the label using the ion sensor; A method for detecting a substance to be detected.

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