Diaphragm sensor and analytical device using the same

Abstract

A diaphragm sensor having a diaphragm that allows a specific substance in a sample solution to pass therethrough, detects the specific substance that has passed through the diaphragm based on current flowing between a working electrode immersed in an internal liquid and a counter electrode, and is an internal liquid replenishment type diaphragm sensor that is capable of replenishing the internal liquid from the outside, includes a housing that houses the internal liquid and an electrode structure from which the working electrode is exposed from a top end surface, and a cover member that is attached to a top end portion of the housing, sandwiches and fixes the diaphragm between the cover member and the housing in a manner opposing the top end surface of the electrode structure, has an opposing surface that opposes the top end surface of the electrode structure, and sandwiches the diaphragm between the top end surface of the electrode structure and the opposing surface of the cover member by a sealing member to thereby fix the diaphragm in a liquid-tight manner.

Description

Technical Field

[0001] This invention relates to a diaphragm sensor for detecting specific substances contained in a sample solution and to an analytical apparatus using the same. Background Technology

[0002] A known diaphragm sensor comprises: a housing containing an internal liquid, a working electrode, and a counter electrode; and a diaphragm liquid-tightly fixed to the housing, allowing a specific substance to permeate through the housing. This diaphragm sensor is used by immersing the diaphragm in a sample solution. The specific substance, such as dissolved oxygen, permeates through the diaphragm and undergoes a reduction reaction on the surface of the working electrode. By measuring the resulting change in current, the concentration of the specific substance can be determined.

[0003] In recent years, such diaphragm sensors, for example, have been known to be internally replenished types, which can replenish internal liquid from an external container to an internal liquid containment space formed inside (e.g., Patent Document 1).

[0004] Existing technical documents

[0005] Patent Document 1: Japanese Patent Publication No. 2010-107335

[0006] However, in the aforementioned internally replenished diaphragm sensors, although replenishing the diaphragm sensor with internal liquid can suppress the deterioration of the internal liquid, the internal liquid storage space is connected to a container placed at atmospheric pressure. Therefore, compared to diaphragm sensors without internal liquid replenishment, the pressure of the internal liquid supporting the diaphragm is lower. Consequently, a problem arises: if the diaphragm is immersed in the sample solution during measurement, the pressure of the sample solution causes the diaphragm to deform, resulting in decreased measurement accuracy. Summary of the Invention

[0007] The present invention was made in view of the above-mentioned problems. The object of the present invention is to provide a diaphragm sensor that can suppress the deterioration of the internal liquid and improve the pressure resistance of the diaphragm.

[0008] That is, the diaphragm sensor of the present invention has a diaphragm that allows a specific substance in a sample solution to pass through. The specific substance passing through the diaphragm is detected based on the current flowing through a working electrode immersed in an internal liquid and between the counter electrode. The diaphragm sensor is an internal liquid replenishment type diaphragm sensor capable of replenishing the internal liquid from the outside. It includes: a housing having a housing portion that houses the internal liquid and an electrode structure, the working electrode being exposed from the top surface of the electrode structure; and a cover member installed at the top surface of the housing portion, clamping and fixing the diaphragm between the cover member and the housing portion in a manner opposite to the top surface of the electrode structure, the cover member having a facing surface opposite to the top surface of the electrode structure, and the diaphragm being liquid-tightly fixed by being clamped between the top surface of the electrode structure and the facing surface of the cover member by a sealing member.

[0009] In the case of such a diaphragm sensor, because it is configured to replenish the internal liquid from the outside, it can suppress deterioration of the internal liquid, such as pH decrease, during measurement. Furthermore, by clamping the diaphragm between the top surface of the electrode structure and the opposite surface of the cover component using a sealing member, the diaphragm is liquid-tightly fixed. Therefore, when the diaphragm is immersed in the sample solution, the pressure of the sample solution does not act on the entire surface of the diaphragm, but is limited to the unsealed portion of the diaphragm, thereby reducing the total force borne by the diaphragm from the sample solution. Moreover, since the area of ​​the diaphragm bearing the pressure of the sample solution is supported from the inside by the top surface of the electrode structure, the electrode structure bears the entire force received from the sample solution, not the diaphragm.

[0010] Thus, the diaphragm sensor according to the present invention can suppress the deterioration of the internal liquid by replenishing the internal liquid from the outside, and can reduce the force on the diaphragm from the sample solution, thereby improving the pressure resistance of the diaphragm.

[0011] Preferably, the diaphragm is pressed against the top surface of the electrode structure by the sealing component.

[0012] Doing so would allow the diaphragm to adhere more closely to the top surface of the electrode structure, so that the electrode structure could bear the force received from the sample solution, thus further improving the pressure resistance of the diaphragm.

[0013] Alternatively, preferably, the top surface of the electrode structure of the diaphragm sensor is bent in a convex manner toward the sample solution side.

[0014] Doing so allows for a closer fit between the diaphragm and the top surface of the electrode structure, thereby further improving the diaphragm's pressure resistance. Additionally, it reduces the space where air bubbles might accumulate on the sample solution side of the diaphragm.

[0015] As a way to more significantly achieve the effects of the present invention, the following can be cited: the containment body has an internal flow channel communicating its outer surface with the internal liquid containment space formed by the containment portion.

[0016] Preferably, a groove is formed on the top surface of the electrode structure to allow internal liquid to flow.

[0017] If this is done, even if the top surface of the electrode structure is held down by a sealing component, the liquid inside the containment section can reliably reach the working electrode through the groove, thus easily ensuring the continuity between the working electrode and the counter electrode.

[0018] To more reliably deliver the internal liquid to the working electrode and more reliably ensure the continuity between the working electrode and the counter electrode, it is preferable that the opposite face of the cover member is annular, and the groove is formed in such a way that it traverses the annular region in the top surface of the electrode structure opposite to the opposite face of the cover member. More preferably, the groove is provided from the outermost edge of the annular region in the top surface across the surface of the working electrode exposed from the top surface.

[0019] Furthermore, the analytical apparatus of the present invention includes: the diaphragm sensor of the present invention; an internal liquid replenishment mechanism including: an internal liquid container for storing the internal liquid; an internal liquid delivery channel for exporting the internal liquid in the internal liquid container to the diaphragm sensor; and a pump, wherein the internal liquid replenishment mechanism replenishes the internal liquid stored in the internal liquid container to the diaphragm sensor by driving the pump.

[0020] If such an analytical device is used, it can achieve the same effect as the diaphragm sensor of the present invention.

[0021] According to the present invention configured in this way, a diaphragm sensor is provided that can suppress the deterioration of the internal liquid and improve the pressure resistance of the diaphragm. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the configuration of an analysis apparatus according to one embodiment of the present invention.

[0023] Figure 2 This is a schematic cross-sectional view showing the configuration of a diaphragm sensor according to the same embodiment.

[0024] Figure 3 yes Figure 2 The enlarged view of part A in the figure is a schematic cross-sectional view showing the structure near the top of the electrode structure.

[0025] Figure 4This is a top view schematically showing the configuration of the top surface of the electrode structure in the same embodiment.

[0026] Figure 5 yes Figure 2 The enlarged view of part A in the figure is a schematic cross-sectional view showing the configuration after the cover component is removed from the housing.

[0027] Figure 6 This is a graph showing the test results using a diaphragm sensor with the same implementation method.

[0028] Figure 7 This is a diagram schematically illustrating the configuration of an analysis apparatus in other embodiments.

[0029] Explanation of reference numerals in the attached figures

[0030] 100...Diaphragm Sensor

[0031] 1···Diaphragm

[0032] 2... Containment Entities

[0033] 21. Containment Department

[0034] 3··· Cover components

[0035] 322···Second Opposite Face (Opposite Face)

[0036] 4···Electrode Structure

[0037] 4s···Top surface

[0038] 42···Working Electrode

[0039] 43··· Counter electrode

[0040] 5. Internal liquid containment space

[0041] S2···O-ring

[0042] L···Internal liquid Detailed Implementation

[0043] The analysis apparatus 400 using a diaphragm sensor 100 according to one embodiment of the present invention will be described below with reference to the accompanying drawings.

[0044] The analytical apparatus 400 of this embodiment measures, for example, the concentration of specific substances such as dissolved oxygen in a sample solution of a drug solution. Specifically, such as... Figure 1As shown, the analytical apparatus 400 includes: an internal liquid replenishment type diaphragm sensor 100, which is immersed in a sample solution and configured to be able to replenish internal liquid from the outside; an internal liquid replenishment mechanism 200, which replenishes internal liquid L to the diaphragm sensor 100; and a control device 300.

[0045] The diaphragm sensor 100 has a diaphragm 1, such as a gas-permeable membrane, that allows a specific substance in the sample solution to permeate. It detects the permeated specific substance based on the current flowing through an electrode structure 4 immersed in an internal liquid L. Specifically, such as... Figure 2 As shown, the diaphragm sensor 100 includes: a housing 2 having a housing portion 21 that houses an internal liquid L and an electrode structure 4; a diaphragm 1 disposed on one surface of the housing 2; and a cover member 3 installed in the housing 2, clamping and fixing the diaphragm 1 between the cover member and the housing 2.

[0046] The housing 2 is generally cylindrical, and at its top end along its axial direction, a cylindrical (here, cylindrical) housing portion 21 is provided coaxially.

[0047] The electrode structure 4 is generally cylindrical and is coaxially housed inside the receiving portion 21. Specifically, the electrode structure 4 includes a support member 41; and a working electrode 42 (cathode), a counter electrode 43 (anode), and a protective electrode 44, which are mounted separately from each other on the support member 41.

[0048] like Figure 2 as well as Figure 3 As shown, the support member 41 is a cylindrical component made of insulating material, surrounding and supporting the rod-shaped working electrode 42, and also wrapping around and supporting the counter electrode 43. Additionally, a cylindrical protective electrode 44 is mounted on the support member 41 surrounding the working electrode 42. Both the working electrode 42 and the protective electrode 44 are configured such that their top surfaces protrude from the top surface 41s of the support member 41, but without forming a step.

[0049] Furthermore, the top surface 41s of the support member 41, the top surface 42s of the working electrode 42 exposed therein (hereinafter also referred to as the working electrode surface), and the top surface 44s of the protective electrode 44 (hereinafter also referred to as the protective electrode surface) constitute the top surface 4s of the electrode structure 4. Figure 4 As shown, the top surface 4s of the electrode structure 4 is circular when viewed from its axial direction. In its central region, the circular working electrode surface 42s and the annular protective electrode surface 44s surrounding it are formed in a concentric circle.

[0050] like Figure 3 as well as Figure 5As shown, the receiving portion 21 has an opening at its top end along its axial direction, and the diaphragm 1 is provided to close the opening of the receiving portion 21. Specifically, the diaphragm 1 is mounted at the top end of the receiving portion 21 such that the central portion of its surface faces and contacts the top end surface 4s of the electrode structure 4. The diaphragm 1 can be made of any material, such as silicon or fluororesin, as long as it allows a specific substance in the sample solution to pass through.

[0051] The cover component 3 is generally cylindrical and is fixedly installed at the top end of the receiving part 21, coaxial with its central axis. For example... Figure 5 As shown, the cover component 3 includes: a cylindrical portion 31, which is configured to be fitted into the outer periphery of the receiving portion 21; and an annular plate-shaped rim portion 32, which extends from the top of the cylindrical portion 31 toward the inner periphery. For example, the inner side of the cylindrical portion 31 is fixed to the outer side of the receiving portion 21 by means of screws, welding, etc., thereby fixing the cover component 3 to the receiving portion 21.

[0052] The cover component 3 has an annular first opposing surface 321 that faces the top surface of the receiving portion 21 when it is fixed to the receiving portion 21. Specifically, the first opposing surface 321 is formed on the inward surface of the rim 32. Furthermore, the outer periphery of the diaphragm 1 is clamped between the annular top surface of the receiving portion 21 and the first opposing surface 321 of the cover component 3 by a sealing member (specifically an O-ring) S1, thereby fixing the diaphragm 1.

[0053] Furthermore, the internal liquid L is contained within an internal liquid containing space 5, which is formed between the inner surface of the containing portion 21 and the outer surface of the electrode structure 4. This internal liquid L can be, for example, an electrolyte such as potassium chloride, a phosphate buffer, an acetate buffer, a borate buffer, or a citrate buffer.

[0054] Furthermore, an internal flow channel is formed within the containment 2, connecting its outer surface to the internal liquid containment space 5. Specifically, the containment 2 includes: a first internal flow channel 61 for introducing internal liquid L replenished from the internal liquid replenishment mechanism 200 into the internal liquid containment space 5; and a second internal flow channel 62 for discharging internal liquid L from the internal liquid containment space 5 to the internal liquid replenishment mechanism 200. Both the first internal flow channel 61 and the second internal flow channel 62 have one end connected to the internal liquid containment space 5 and the other end open on the outer surface of the containment 2, forming an internal liquid inlet and an internal liquid outlet, respectively.

[0055] The internal liquid replenishment mechanism 200 maintains the pH of the internal liquid L within the diaphragm sensor 100 at a predetermined value or below by periodically replenishing the internal liquid L to the diaphragm sensor 100. In this embodiment, the internal liquid replenishment mechanism 200 is a circulating mechanism that circulates the internal liquid L between the internal liquid replenishment mechanism 200 and the diaphragm sensor 100. Specifically, the internal liquid replenishment mechanism 200 includes: an internal liquid container 210 for storing the internal liquid L; an internal liquid delivery channel 220 for discharging the internal liquid L from the internal liquid container 210 to the diaphragm sensor 100; an internal liquid return channel 230 for discharging the internal liquid L from the diaphragm sensor 100 back to the internal liquid container 210; a pump P disposed on the internal liquid return channel 230; and multiple switching valves V (solenoid valves) disposed on each channel.

[0056] In this embodiment, the internal liquid container 210 stores the internal liquid L supplied to the diaphragm sensor 100 and the internal liquid L recovered from the diaphragm sensor 100 in a mixed manner without distinction. The pressure of the internal liquid container 210 is at atmospheric pressure, and the pressure of the internal liquid L flowing through the circulation system including the internal liquid container 210 is at or below atmospheric pressure.

[0057] One end of the internal liquid delivery channel 220 is connected to the outlet of the internal liquid container 210, and the other end is connected to the internal liquid inlet of the diaphragm sensor 100. One end of the internal liquid return channel 230 is connected to the internal liquid outlet of the diaphragm sensor 100, and the other end is connected to the inlet of the internal liquid container 210. Furthermore, by periodically operating the pump P through the control device 300, the internal liquid L circulates between the internal liquid container 210 and the diaphragm sensor 100 through the internal liquid delivery channel 220 and the internal liquid return channel 230.

[0058] The control device 300 is a general-purpose or special-purpose computer equipped with a CPU, memory, and input / output interfaces. The control unit 320 coordinates the CPU with peripheral devices according to a predetermined program stored in a predetermined area of ​​the memory, thereby performing at least the functions of the measurement unit 310 and the control unit 320.

[0059] When the measuring unit 310 applies a measuring voltage between the working electrode 42 and the counter electrode 43, it obtains the current value flowing between the working electrode 42 and the counter electrode 43, and calculates the concentration of a specific substance in the sample solution based on this value.

[0060] The control unit 320 controls the pump P and the switching valve V of the internal liquid replenishment mechanism 200 to periodically replenish the internal liquid L to the diaphragm sensor 100. Specifically, the control unit 320 periodically circulates the internal liquid L so that the pH of the internal liquid L contained in the diaphragm sensor 100 is below a specified value (e.g., pH 8.5 or below).

[0061] Therefore, in order to improve the pressure resistance of the diaphragm 1, the cover member 3 of the analytical apparatus 400 of this embodiment has an annular second opposing surface 322 opposite to the top surface 4s of the electrode structure 4. The diaphragm 1 is clamped between the top surface 4s of the electrode structure 4 and the annular second opposing surface 322 of the cover member 3 by an O-ring S2, thereby being liquid-tightly fixed. Specifically, the diaphragm 1 is pressed and fixed to the top surface 4s of the electrode structure 4 by the O-ring S2, and the O-ring S2 is pressed from the top side to the base side by the second opposing surface 322.

[0062] Specifically, the second opposing surface 322 is formed in a ring shape on the inward surface of the eaves 32 of the cover member 3, further inward than the first opposing surface 321. For example... Figure 3 as well as Figure 4 As shown, when viewed from its axial direction, the second opposing surface 322 is concentric with the top surface 4s of the electrode structure 4 and is formed in a manner that surrounds the working electrode surface 42s and the protective electrode surface 44s.

[0063] In addition, such as Figure 4 As shown, multiple grooves 45 for internal liquid L to flow through are formed on the top surface 4s of the electrode structure 4. Each groove 45 is formed as a straight line that, when viewed from above, traverses the annular region 4p opposite to the second opposing surface 322 and the protective electrode surface 44s of the top surface 4s of the electrode structure 4. Specifically, each groove 45 is provided across the working electrode surface 42s from the outermost edge of the annular region 4p. Each groove 45 is formed so that it is point-symmetric about the center of the top surface 4s of the electrode structure 4 when viewed from the axial direction of the electrode structure 4.

[0064] Furthermore, the top surface 4s of the electrode structure 4 is formed in a convex shape from the base end to the top end. Specifically, the top surface 4s of the electrode structure 4 is formed in a spherical or non-spherical shape, with the central portion of the working electrode surface 42s protruding towards the top end.

[0065] The analytical apparatus 400 of this embodiment, configured in this way, is designed to periodically replenish the internal liquid L to the diaphragm sensor 100 from the internal liquid replenishment mechanism 200, thus suppressing deterioration such as pH decrease of the internal liquid L contained within the diaphragm sensor 100. Furthermore, in the diaphragm sensor 100, the diaphragm 1 is liquid-tightly fixed by clamping it between the top surface 4s of the electrode structure 4 and the second opposing surface 322 of the cover member 3 via an O-ring S2. Therefore, when the diaphragm 1 is immersed in the sample solution, the pressure of the sample solution does not act on the entire surface of the diaphragm 1, but is limited to the portion not sealed by the O-ring S2, thereby reducing the total force borne by the diaphragm 1 from the sample solution. Moreover, since the area of ​​the diaphragm 1 where the pressure of the sample solution is applied is supported from the inside by the top surface 4s of the electrode structure 4, all the force received from the sample solution is not borne by the diaphragm 1, but by the electrode structure 4. Therefore, by replenishing the internal liquid L to the diaphragm sensor 100 from the internal liquid replenishment mechanism 200, the deterioration of the internal liquid L can be suppressed, and the force exerted on the diaphragm 1 by the sample solution can be reduced, thereby improving the pressure resistance of the diaphragm 1. Thus, when the diaphragm 1 is immersed in the sample solution, deformation of the diaphragm 1 can be prevented, enabling high-precision measurement of the concentration of a specific substance. Furthermore, since the top surface 4s of the electrode structure 4 is curved in a convex manner towards the measurement solution side, the space where air bubbles might accumulate closer to the measurement solution side of the diaphragm 1 can be reduced.

[0066] Here, in Figure 6 Test data confirming the effectiveness of the diaphragm sensor 100 of this embodiment in suppressing the deterioration of the internal liquid L is shown. In this test, one of the aforementioned diaphragm sensor 100 as a test example and one of a conventional type diaphragm sensor as a comparative example (i.e., (i) internal liquid not replenished, (ii) the spacer membrane between the electrode structure and the cover member is not liquid-tightly fixed) were prepared and immersed in a 28% ammonia stock solution as the measurement solution. They were left to stand at room temperature in the measurement state, and the pH value of the internal liquid in the sensor was measured. Furthermore, for the diaphragm sensor as a test example, the internal liquid was replenished and replaced at a flow rate of 40 μl / 2 hours, while the internal liquid of the diaphragm sensor as a comparative example was not replenished. Figure 6 As shown, in the diaphragm sensor used as a comparative example, the pH value of the internal liquid rose immediately after the measurement began, and Ag precipitated on the electrode surface after 5 days. On the other hand, in the diaphragm sensor 100 used as a test example, the pH value did not change significantly after the measurement began, and it was able to maintain a state below pH 7 for 120 days.

[0067] Furthermore, the present invention is not limited to the embodiments described herein.

[0068] For example, the internal liquid replenishment mechanism 200 in the described embodiment is a cyclic mechanism that circulates the internal liquid L between the internal liquid replenishment mechanism 200 and the diaphragm sensor 100; however, it may not be a cyclic mechanism in other embodiments. In this case, for the internal liquid replenishment mechanism 200, for example, as... Figure 7 As shown, it may also include: an internal liquid container 210 for storing internal liquid L that is replenished to the diaphragm sensor 100; and a waste liquid container 240 for storing internal liquid L that is returned from the diaphragm sensor 100.

[0069] Furthermore, in the embodiment described above, the diaphragm 1 of the diaphragm sensor 100 is liquid-tightly fixed between the second opposing surface 322 of the cover member 3 and the top surface 4s of the electrode structure 4 by an O-ring S2, but this is not the only embodiment. In another embodiment, the diaphragm 1 may also be liquid-tightly fixed between the second opposing surface 322 of the cover member 3 and the top surface 4s of the electrode structure 4 by a plurality of O-rings S2 arranged in a concentric circle.

[0070] Furthermore, in the diaphragm sensor 100 of the described embodiment, the diaphragm 1 is pressed against the top surface 4s of the electrode structure 4 by the O-ring S2, thereby being liquid-tightly fixed, but this is not the only embodiment. In another embodiment, the diaphragm 1 may also be pressed against the second opposing surface 322 of the cover member 3 by the O-ring S2, thereby being liquid-tightly fixed.

[0071] Furthermore, in the diaphragm sensor 100 of the described embodiment, the top surface 4s of the electrode structure 4 is formed in a convex shape, but this is not a limitation. In another embodiment, the top surface 4s of the electrode structure 4 may also be formed flat without bending.

[0072] Furthermore, in the diaphragm sensor 100 of the described embodiment, each groove 45 formed on the top surface 4s of the electrode structure 4 is straight, but is not limited to this. In another embodiment, each groove 45 may also be formed in any shape, such as curved or sawtooth. Even if it is any shape, each groove 45 only needs to be formed to traverse the annular region 4p in the top surface 4s of the electrode structure 4 and the protective electrode surface 44s.

[0073] Furthermore, in the diaphragm sensor 100 of the above embodiment, the top surface 4s of the electrode structure 4 is formed with the top surface 41s of the support member 41, the working electrode surface 42s, and the protective electrode surface 44s without any steps between them, but it is not limited to this. For example, in another embodiment, the working electrode surface 42s may be configured to protrude further to the top side than the top surface 41s of the support member 41.

[0074] Furthermore, while the sealing component S2 in the aforementioned embodiment is an O-ring, it is not limited to this. In other embodiments, the sealing component S2 can be made of any component, such as a gasket, as long as it is a component capable of liquid-tightly fixing the diaphragm 1.

[0075] Furthermore, the present invention is not limited to the described embodiments, and various modifications can be made without departing from the spirit of the present invention.

Claims

1. A diaphragm sensor, characterized in that, The diaphragm sensor has a diaphragm that allows specific substances in the sample solution to pass through. The specific substances passing through the diaphragm are detected based on the current flowing through a working electrode immersed in an internal liquid and between the counter electrode. The diaphragm sensor is an internally replenished diaphragm sensor capable of receiving external replenishment of the internal liquid. The diaphragm sensor includes, A housing having a housing section that houses the internal liquid and an electrode structure, wherein the working electrode protrudes from the top surface of the electrode structure; as well as A cover component is installed at the top end of the receiving portion, and the diaphragm is clamped and fixed between the cover component and the receiving portion in such a way that it faces the top end surface of the electrode structure. The cover component has a facing surface opposite to the top surface of the electrode structure. The diaphragm is liquid-tightly fixed by being clamped between the top surface of the electrode structure and the opposite surface of the cover component by a sealing member.

2. The diaphragm sensor according to claim 1, characterized in that, The diaphragm is pressed against the top surface of the electrode structure by the sealing component.

3. The diaphragm sensor according to claim 1 or 2, characterized in that, The top surface of the electrode structure is bent in a convex shape toward the sample solution side.

4. The diaphragm sensor according to any one of claims 1 to 3, characterized in that, The containment body has an internal flow channel connecting its outer surface with the internal liquid containment space formed by the containment portion.

5. The diaphragm sensor according to any one of claims 1 to 4, characterized in that, A groove is formed on the top surface of the electrode structure to allow the internal liquid to flow.

6. The diaphragm sensor according to claim 5, characterized in that, The opposite surfaces of the cover component are annular. The groove is formed in a ring-shaped region that runs through the top surface of the electrode structure and is opposite to the opposite surface of the cover component.

7. The diaphragm sensor according to claim 6, characterized in that, The groove is provided across the surface of the working electrode exposed from the top surface, extending from the outermost edge of the annular region in the top surface.

8. An analytical apparatus, characterized in that, The analytical device includes: The diaphragm sensor as described in any one of claims 1 to 7; and An internal liquid replenishment mechanism includes: an internal liquid container for storing the internal liquid; an internal liquid delivery channel for discharging the internal liquid from the internal liquid container to the diaphragm sensor; and a pump, wherein the internal liquid replenishment mechanism replenishes the internal liquid stored in the internal liquid container to the diaphragm sensor by driving the pump.

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