Electrode body for ion sensor and method for manufacturing ion sensor

Abstract

The purpose of the present invention is to provide an electrode body for an ion sensor, with which degradation in performance is reduced by improving an adhesion strength without depending on the materials of an electrode body and an ion-sensitive membrane. For this purpose, the present invention is an electrode body for an ion sensor, the electrode body comprising: an internal electrode that outputs a potential to an ion-sensitive membrane; and an electrode body that accommodates an internal solution electrically connecting the internal electrode and the ion-sensitive membrane. The electrode body has a flow path through which a liquid containing a specimen to be measured flows, and a placement surface on which the ion-sensitive membrane is placed. The placement surface and the ion-sensitive membrane are welded via a compatibilizer.

Description

Electrode body for ion sensor and method of manufacturing ion sensor

[0001] The present invention relates to an electrode body for an ion sensor and a method for manufacturing an ion sensor.

[0002] Analytical devices such as clinical analyzers, water quality analyzers, soil analyzers, and food analyzers are often equipped with ion sensors that measure the concentration of ionic electrolytes in a sample. An ion sensor generally consists of an electrode body, an internal solution, an ion-sensitive membrane, and an internal electrode. The electrode body of a flow-type ion sensor has a sample flow path, and a through-hole is provided in a portion of the side of the sample flow path. The through-hole is then covered with an ion-sensitive membrane to form a response surface, and the electrode body and the ion-sensitive membrane are bonded together at a location other than the response surface.

[0003] However, variations in the electrode body and the ion-sensitive membrane weaken the adhesive strength between them, which can easily cause the sensitive surface to peel off and result in poor performance. Therefore, the technology described in Patent Document 1 improves the adhesive strength between the electrode body and the ion-sensitive membrane by applying water to the mounting surface of the electrode body on which the ion-sensitive membrane is mounted and welding the electrode body and the ion-sensitive membrane while the water is present on the mounting surface.

[0004] International Publication No. 2022 / 014095

[0005] The technique described in Patent Document 1 has a problem in that the adhesive strength cannot be improved unless the electrode body and the ion-sensitive membrane are made of organic polymers that are compatible with each other.

[0006] An object of the present invention is to provide an electrode body for an ion sensor and a method for manufacturing an ion sensor that have fewer performance defects by improving adhesive strength regardless of the materials of the electrode body and ion-sensitive membrane.

[0007] In order to solve the above-mentioned problems, the present invention provides an electrode body for an ion sensor, which comprises an internal electrode that outputs an electric potential to an ion-sensitive membrane, and an electrode body that contains an internal solution that electrically connects the internal electrode and the ion-sensitive membrane, wherein the electrode body has a flow path through which a liquid containing a sample to be measured flows, and a mounting surface on which the ion-sensitive membrane is placed, and the mounting surface and the ion-sensitive membrane are welded together via a compatibilizer.

[0008] The present invention also provides a method for manufacturing an ion sensor in which an ion-sensitive membrane is fixed to an electrode body that contains an internal solution and has an internal electrode, the method comprising the steps of: applying a compatibilizer to a mounting surface of an electrode body on which the ion-sensitive membrane is to be mounted; mounting the ion-sensitive membrane with the compatibilizer present on the mounting surface; and welding the mounting surface and the ion-sensitive membrane via the compatibilizer.

[0009] According to the present invention, it is possible to provide an electrode body for an ion sensor and a method for manufacturing an ion sensor that have few performance defects by improving the adhesive strength regardless of the materials of the electrode body and the ion-sensitive membrane.

[0010] 2 is a diagram showing an outline of the configuration of an ion sensor according to an embodiment of the present invention; 3 is a flowchart showing a manufacturing method of an ion sensor according to an embodiment of the present invention; 4 is a diagram showing a coating process in step S1 of FIG. 2; 5 is a diagram showing a mounting process in step S2 of FIG. 2; 6 is a diagram showing a welding process in step S3 of FIG. 2; and 7 is a diagram showing an assembly process in step S4 of FIG. 2.

[0033] Figures 2A and 2B show the state of the opposing surfaces of an electrode body and an ion-sensitive membrane, where (a) is a comparative example 1 in which no water or compatibilizer is used, (b) is a comparative example 2 in which water is used, and (c) is a case in which a compatibilizer is used as in this embodiment.

[0034] Figure 2B is a graph comparing the adhesive strength between an electrode body and an ion-sensitive membrane when a crystalline compatibilizer is used and when a non-crystalline compatibilizer is used.

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0012] First, the configuration of the ion sensor according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an outline of the configuration of the ion sensor according to this embodiment. The ion sensor is mainly composed of an ion sensor electrode body and an ion-sensitive membrane 4. The ion sensor electrode body includes an internal electrode 11 that outputs a potential to the ion-sensitive membrane 4, an electrode body 2 that contains an internal solution (not shown) that electrically connects the internal electrode 11 and the ion-sensitive membrane 4, an electrode body pin 12 that seals the internal solution to prevent leakage, and an electrode body plate 9 that forms the bottom surface that contains the internal container.

[0013] The electrode body 2 has an analyte flow path 13 formed therein through which a liquid containing the analyte to be measured flows, and a mounting surface 3 on which the ion-sensitive membrane 4 is placed (see FIG. 3 , etc., described later). While the front wall of the electrode body 2 is not shown in FIG. 1 and other figures for clarity, this is for illustrative purposes only; in reality, a wall similar to the rear wall is provided. The electrode body 2 has a rectangular parallelepiped shape with external dimensions of approximately 11 mm × 20 mm × 24 mm, the analyte flow path 13 has a diameter of approximately 1 mm, and the mounting surface 3 is approximately 5 mm × 5 mm. A portion of the analyte flow path 13 is exposed to the mounting surface 3, forming an oval through-hole 6 (see FIG. 3 , described later) of approximately 0.9 mm × 3 mm, which allows the analyte to contact the ion-sensitive membrane 4. The electrode body 2 may be entirely made of a thermoplastic resin or a hard resin containing a pigment. Alternatively, the electrode body 2 may be formed by coating a pigment on the mounting surface 3 thereof, separate from the electrode body main body made of hard resin.

[0014] 1, in the ion sensor according to this embodiment, the mounting surface 3 of the electrode body 2 and the ion-sensitive membrane 4 are fixed to each other by welding via a compatibilizer. Details of the compatibilizer will be described later.

[0015] The method for manufacturing the ion sensor will be described with reference to Fig. 2 to Fig. 6. Fig. 2 is a flowchart showing the method for manufacturing the ion sensor, and Fig. 3 to Fig. 6 are diagrams for explaining each step in the method for manufacturing the ion sensor.

[0016] First, a coating step is performed in which a compatibilizer 5 is applied to the mounting surface 3 of the electrode body 2 or the mounting surface side of the ion-sensitive membrane 4 (step S1). Figure 3 is a diagram showing the coating step in step S1 of Figure 2. The compatibilizer 5 has an amphiphilic composition that is soluble in both the organic polymer that constitutes the electrode body 2 and the organic polymer that constitutes the ion-sensitive membrane 4. Note that the compatibilizer 5 applied to the mounting surface 3 is held on the surface of the mounting surface 3 by surface tension, and therefore does not flow down through the penetration 6 into the specimen flow path 13.

[0017] Next, a mounting step is performed in which the ion-sensitive membrane 4 is mounted from above on the mounting surface 3 of the electrode body 2 (before the compatibilizer 5 evaporates and disappears) with the compatibilizer 5 remaining on the mounting surface 3 other than the through-hole 6 or on the mounting surface side of the ion-sensitive membrane 4 (step S2). Figure 4 is a diagram showing the mounting step in step S2 of Figure 2. Here, the ion-sensitive membrane 4 is formed from a soft or hard resin material with a diameter of approximately 5 mm and a thickness of approximately 0.1 mm to 0.5 mm.

[0018] Subsequently, a welding process is performed in which pressure is applied to the ion-sensitive membrane 4 from the opposite side of the electrode body 2, and a welding means 7 is used to weld the electrode body 2 and the ion-sensitive membrane 4 together (step S3). FIG. 5 is a diagram illustrating the welding process in step S3 of FIG. 2 . A weight 8 is used to apply pressure, and the ion-sensitive membrane 4 is pressed vertically against the mounting surface 3 of the electrode body 2, sandwiching the compatibilizer 5 therebetween. By applying a pressure of approximately 10 N to 100 N to the entire ion-sensitive membrane 4 with the weight 8, good adhesion between the electrode body 2, the compatibilizer 5, and the ion-sensitive membrane 4 is achieved. The weight 8 can be made of transparent glass, such as quartz glass, or ceramic. The lower end surface of the weight 8, which is in contact with the ion-sensitive membrane 4, is approximately the same size as the mounting surface 3 of the electrode body 2 and has a similar shape. The pressure may be obtained not only by the gravity of the weight 8 itself but also by an external force such as a servo motor.

[0019] Here, a specific description will be given of the welding means 7. Possible welding means 7 include an organic solvent, a laser irradiator, and an ultrasonic irradiator, but in this embodiment, the use of an organic solvent and the use of a laser irradiator will be described as examples.

[0020] First, when an organic solvent is used, in the application process of step S1, a volatile organic solvent is applied to the mounting surface 3 together with the compatibilizer 5. Then, in the welding process of step S3, the organic polymer constituting the electrode body 2 and the organic polymer constituting the ion-sensitive film 4 are dissolved in the organic solvent, and welding is performed by evaporating the organic solvent while applying stress in the direction of the sensitive surface.

[0021] On the other hand, when laser irradiation is used, in the welding process of step S3, laser light is irradiated from above the ion-sensitive membrane 4 (the side opposite the electrode body 2) while the ion-sensitive membrane 4 is pressed against the mounting surface 3. The laser light is light with a wavelength in the far-infrared region emitted from a laser irradiator, which is the welding means 7. When the laser light is irradiated onto the entire mounting surface 3 or the entire weight 8, the energy of the laser light is converted into thermal energy, and the mounting surface 3 melts due to heat generation. Furthermore, the laser light irradiation is performed while pressure is being applied by the weight 8, and the ion-sensitive membrane 4 is pressed against the molten mounting surface 3, making them more easily bonded to each other. Furthermore, applying pressure for approximately 1 to 20 seconds after the end of laser light irradiation improves the adhesive strength between the ion-sensitive membrane 4 and the mounting surface 3 near the penetration 6. It is desirable to use a material that is prone to generate thermal energy and has a lower melting point than the ion-sensitive membrane 4 for at least the mounting surface 3 of the electrode body 2. The ion-sensitive film 4 transmits wavelengths in the far-infrared region and has a higher melting point than the electrode body 2 on the mounting surface 3. The material of the weight 8 may be transparent glass such as quartz glass, or ceramic, but is not limited to these as long as it is a material that transmits wavelengths in the far-infrared region.

[0022] Next, after the welding process in step S3 is completed, the final assembly process of the ion sensor begins (step S4). Figure 6 shows the assembly process in step S4 of Figure 2. In this assembly process, first, the electrode body plate 9 is adhesively fixed to the electrode body 2, and the internal solution is filled through the hole 10. Next, the internal electrode 11 is inserted through the hole 10 and adhesively fixed to the electrode body 2, and then the electrode body pin 12 is inserted through the hole 10 and adhesively fixed to the electrode body 2. This completes the manufacture of the ion sensor.

[0023] The effect of the compatibilizer 5 in the ion sensor according to this embodiment will be described below. Figure 7 shows the state of the opposing surfaces of the electrode body and the ion-sensitive membrane when pressure is applied to the ion-sensitive membrane with a weight, where (a) is a comparative example 1 in which no water or compatibilizer is used, (b) is a comparative example 2 in which water is used, and (c) is a case in which a compatibilizer is used as in this embodiment. Here, a laser irradiator is used as the welding means 7.

[0024] First, in the case of Comparative Example 1 shown in FIG. 7( a ), a gap 14 exists between the electrode body 2 and the ion-sensitive membrane 4 , making it difficult for thermal energy to be transmitted uniformly between the electrode body 2 and the ion-sensitive membrane 4 .

[0025] 7( c), on the other hand, the gap 14 between the electrode body 2 and the ion-sensitive membrane 4 is filled with the compatibilizer 5, so that thermal energy is uniformly transmitted, and the organic polymer of the electrode body 2 on the mounting surface 3 melts with the organic polymer of the ion-sensitive membrane 4. At this time, a mixed layer 50 in which the molten organic polymer and the compatibilizer 5 are mixed is formed between the electrode body 2 and the ion-sensitive membrane 4, improving the adhesive strength between the electrode body 2 and the ion-sensitive membrane 4. As a result, according to this embodiment, even if there is material variation in the electrode body 2, the adhesive strength between the electrode body 2 and the ion-sensitive membrane 4 is strong, so that poor performance due to peeling of the sensitive surface can be suppressed, and stable quality and a high yield can be obtained.

[0026] Furthermore, in the case of Comparative Example 2 (Patent Document 1) shown in Figure 7(b), the gap 14 between the electrode body 2 and the ion-sensitive membrane 4 is filled with water 15, so that thermal energy is uniformly transmitted, and the organic polymer of the electrode body 2 on the mounting surface 3 and the organic polymer of the ion-sensitive membrane 4 melt. At this time, although the water 15 itself evaporates, the adhesion strength between the electrode body 2 and the ion-sensitive membrane 4 is improved due to the welding of the organic polymers. However, there is a problem in that the adhesion strength cannot be improved unless the combination of the electrode body 2 and the ion-sensitive membrane 4 is made of organic polymers that are compatible with each other. For example, the following combinations of organic polymers are difficult to dissolve in each other: polyethylene (PE) and polyvinyl chloride (PVC), polypropylene (PP) and polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP), polyethylene (PE) and polystyrene (PS), polystyrene (PS) and polyimide (PI), polystyrene (PS) and polymethyl methacrylate (PMMA), polystyrene (PS) and polybutylene (PB), polystyrene (PS) and polyethylene oxide (PEO), polystyrene (PS) and polycarbonate (PC), poly(methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS), polyurethane (PU) and polydimethylsiloxane (PDMS), etc. Therefore, in Comparative Example 2, when the organic polymer constituting the electrode body 2 and the organic polymer constituting the ion-sensitive membrane 4 are combined in these ways (including the reverse), it is difficult to weld them together, and the adhesive strength cannot be improved.

[0027] On the other hand, in this embodiment, the electrode body 2 (mounting surface) and the ion-sensitive membrane 4 can be welded together by using a compatibilizer 5 suitable for the combination of the organic polymer constituting the electrode body 2 and the organic polymer constituting the ion-sensitive membrane 4. In other words, the adhesive strength can be improved and an ion sensor with fewer performance defects can be realized, regardless of the materials of the electrode body 2 and the ion-sensitive membrane 4. Furthermore, the inventors have confirmed that the compatibilizer 5 for welding the electrode body 2 and the ion-sensitive membrane 4 can be selected for at least the combinations listed above. For example, when one of the electrode body 2 and the ion-sensitive membrane 4 is made of PE and the other is made of PVC, chlorinated polyethylene is selected as the compatibilizer 5. Furthermore, when one of the electrode body 2 and the ion-sensitive membrane 4 is made of PP and the other is made of PVC, chlorinated polypropylene is selected as the compatibilizer 5.

[0028] Unlike an adhesive, the compatibilizer 5 undergoes a chemical reaction with the electrode body 2 and the ion-sensitive membrane 4. Rather, it merely assists in welding the electrode body 2 and the ion-sensitive membrane 4. Therefore, the chemical structure of the compatibilizer 5 itself does not change before or after the welding process. The compatibilizer 5 remains as part of the ion sensor after the assembly process. However, except for a certain degree of deterioration, its chemical structure basically remains unchanged, allowing the performance of the ion sensor to be maintained. Furthermore, it is desirable for the compatibilizer 5 to have a melting point higher than the melting points of the organic polymers constituting the electrode body 2 and the organic polymers constituting the ion-sensitive membrane 4. This is because, if the compatibilizer 5 melts before the electrode body 2 and the ion-sensitive membrane 4 when thermal energy is transmitted during the welding process, the effect of improving the adhesive strength between the electrode body 2 and the ion-sensitive membrane 4 will be reduced.

[0029] 8 is a graph comparing the adhesive strength between the electrode body 2 and the ion-sensitive membrane when a crystalline compatibilizer is used and when a non-crystalline compatibilizer is used. Here, the adhesive strength between the electrode body 2 and the ion-sensitive membrane 4 in the ion sensor manufactured by the conventional method corresponding to the above-mentioned Comparative Example 1 is set to 1. FIG. 8 shows that the adhesive strength of the non-crystalline compatibilizer is stronger than that of the crystalline compatibilizer. Furthermore, the compatibilizer 5 is preferably non-ionic so as not to affect the analytical performance of the ion sensor.

[0030] The above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the described configurations. Furthermore, some of the configurations of the embodiment may be added to, deleted from, or replaced with other configurations.

[0031] 2...electrode body, 3...mounting surface, 4...ion-sensitive membrane, 5...compatibilizer, 6...penetration portion, 7...welding means, 8...weight, 9...electrode body plate, 10...hole portion, 11...internal electrode, 12...electrode body pin, 13...analyte flow path, 14...gap, 15...water, 50...mixed layer

Claims

1. An electrode body for an ion sensor comprising an internal electrode that outputs an electric potential to an ion-sensitive membrane, and an electrode body containing an internal solution that electrically conducts the internal electrode and the ion-sensitive membrane, wherein the electrode body has a channel through which a liquid containing the sample to be measured flows, and a mounting surface on which the ion-sensitive membrane is placed, An electrode body for an ion sensor, characterized in that the mounting surface and the ion-sensitive film are welded together via a compatibilizer, and the compatibilizer has a melting point higher than the melting point of the organic polymer constituting the electrode body and the melting point of the organic polymer constituting the ion-sensitive film.

2. In the electrode body for ion sensor according to claim 1, The aforementioned compatibilizer is characterized by being amorphous, and is an electrode body for an ion sensor.

3. In the electrode body for ion sensor according to claim 1, The aforementioned compatibilizer is nonionic, and is used as an electrode body for an ion sensor.

4. (delete)

5. In the electrode body for ion sensor according to claim 1, Between the mounting surface and the ion-sensitive film, An electrode body for an ion sensor, characterized in that a layer is formed in which the organic polymer constituting the electrode body, the organic polymer constituting the ion-sensitive membrane, and the compatibilizer are mixed together.

6. In the electrode body for ion sensor according to claim 1, The combinations of the organic polymer constituting the electrode body and the organic polymer constituting the ion-sensitive membrane, including the case where the combinations are reversed, include polyethylene and polyvinyl chloride, polypropylene and polyvinyl chloride, polyethylene and polypropylene, polyethylene and polystyrene, polystyrene and polyimide, polystyrene and polymethyl methacrylate, polystyrene and polybutylene, polystyrene and polyethylene oxide, polystyrene and polycarbonate, polymethyl methacrylate and polydimethylsiloxane, polyurethane and polydimethylsiloxane, An electrode body for an ion sensor, characterized by being one of the following.

7. In the electrode body for ion sensor according to claim 1, Of the electrode body and the ion-sensitive membrane, one is made of polyethylene and the other is made of polyvinyl chloride. The electrode body for an ion sensor is characterized in that the compatibilizer is chlorinated polyethylene.

8. In the electrode body for ion sensor according to claim 1, Of the electrode body and the ion-sensitive film, one is made of polypropylene and the other is made of polyvinyl chloride. The electrode body for an ion sensor is characterized in that the compatibilizer is chlorinated polypropylene.

9. A method for manufacturing an ion sensor, comprising fixing an ion-sensitive film to an electrode body that contains an internal solution and is equipped with internal electrodes, The process includes a coating step of applying a compatibilizer having a melting point higher than the melting point of the organic polymer constituting the electrode body and the melting point of the organic polymer constituting the ion-sensitive film to the mounting surface of the electrode body on which the ion-sensitive film is placed, A method for manufacturing an ion sensor, comprising: a placement step of placing the ion-sensitive film on the placement surface in which the compatibilizer is present; and a welding step of welding the placement surface, the ion-sensitive film, and the compatibilizer together.

10. In the method for manufacturing an ion sensor according to claim 9, A method for manufacturing an ion sensor, characterized in that the compatibilizer does not change its chemical structure before and after the welding process.