JP2019184390A - Electrode chip for electrochemical sensor and method for manufacturing the same - Google Patents

Abstract

To provide an electrode chip for an electrochemical sensor which has an easily-obtainable carbon electrode, exhibits an increased measurement accuracy, and allows the measurement of a plurality of chemical substances, and a method for manufacturing the electrochemical sensor.SOLUTION: The electrode chip includes: an insulating supporting body; and at least one electrode including an action electrode. The at least one electrode protrudes from the supporting body and includes a base body made of a conductive surface, and at least a part of the surface of the base body is coated with a protective layer made of a carbon film and having a thickness of at least 1 μm. The surface of the protective layer is provided with a catalyst at least partially. There is also provided a method for manufacturing the electrode chip.SELECTED DRAWING: Figure 1

Description

  The present invention relates to the field of measuring the concentration of a chemical substance by electrochemical measurement, and more particularly to the field of biosensing that measures the concentration of a chemical substance contained in a body fluid using a body fluid as a sample.

  There are various biosensing techniques, but electrochemical techniques are widely used because, for example, the measurement of blood sugar levels can detect trace components with high sensitivity. In the electrochemical technique, biological information that is a chemical characteristic can be detected as an electrical signal, and thus there is an advantage that it is easy to process and analyze a signal obtained using a semiconductor device or the like. For this reason, development of new electrochemical sensing devices and sensing methods using the same has been actively carried out worldwide.

  Electrochemical sensors collect gas generated from living organisms such as sweat and breath, and gases in the environment, and various chemical substances contained in the sample are adsorbed to sensitive substances covering the electrodes, and the current flowing between the electrodes. By measuring and analyzing changes in values, resistance values, and capacitance values, information serving as an index (biomarker) for grasping the characteristics and state of a living body is acquired.

  Electrochemical measurements include a tripolar method in which measurement is performed using three electrodes, a working electrode, a reference electrode, and a counter electrode, and a bipolar method in which measurement is performed by using both the reference electrode and the counter electrode as one electrode. Is widely known. Conventional techniques of electrochemical sensors for performing such measurements are disclosed in, for example, documents such as Japanese Patent Application Laid-Open No. 2002-55076 (Patent Document 1).

  The working electrode is sensitive to electrochemical response to a minute amount of material in the sample on the electrode surface, and the counter electrode is for setting a potential difference or flowing current between the working electrode. is there. That is, a voltage or current is applied between the counter electrode and the working electrode, and a current or potential corresponding to the voltage or current is measured. When the current is measured, if this measurement is continuously performed, the amount of electricity can be obtained by integrating the current with time.

  The reference electrode in the triode method is an electrode that does not react with the target substance and maintains a constant potential, and maintains a constant potential difference between the reference electrode and the counter electrode, and measures a current flowing between the working electrode and the counter electrode. . Alternatively, a concentration of the target substance is measured by passing a constant current between the working electrode and the counter electrode and measuring a potential difference between the reference electrode and the counter electrode (for example, Patent Document 2).

  In particular, in a method in which body fluid collected from a living body is obtained ex vivo (in vitro) using a biological sensor placed away from the living body, a sample part and a measuring part are provided separately, and a sample such as body fluid is attached to the sample part. Therefore, many methods are employed in which this is electrically connected to a measurement unit for measurement.

  In the above method, the possibility of contaminating the measurement part with bodily fluids can be kept low, and the sample part only can be made disposable, thereby reducing the time and effort required for washing, and the influence on the measurement value due to unwashed parts. There are advantages to doing it.

  However, when it is intended for such a single use, the most important thing is the cost. For this reason, as an electrode material, there are many that use carbon which is an inexpensive and electrochemically inexpensive material.

  Conventional electrodes made of carbon include electrochemically stable electrodes such as diamond-like carbon, glassy carbon, and boron dove diamond electrode, but these are expensive and are not suitable for disposable applications. For this reason, most of them use a carbon paste or a carbon deposited film formed by sputtering.

  In electrochemical analysis, in order to improve the accuracy, a method of detecting a large amount of electrical signals related to the reaction by increasing the surface area or selectively extracting the reaction in a specific chemical substance by modifying the surface is used. ing. In order to increase the surface area of the electrode, a method of increasing the contact area between the sample and the electrode by increasing the installation area of the electrode can be considered, but this method has a problem in that a large amount of sample liquid is required.

  Furthermore, although proposals have been made to process the electrode shape into a three-dimensional shape, the existing carbon paste printing method or sputtering method requires the formation of one surface at a time, leaving problems in terms of the number of processes and cost.

  On the other hand, a method for improving sensitivity using carbon nanotubes has been devised. For example, Patent Document 3 devises a method of electrodepositing carbon nanotubes and nucleic acids. In this method, it has been proposed to deposit carbon nanotubes and nucleic acids on the underlying metal by electrodeposition, but in order to suppress the occurrence of rust and electrochemical properties of the underlying metal, It is necessary to coat the base metal with a sufficiently dense electrodeposition film so that the resulting liquid does not contact the metal, or to suppress rust using a noble metal. However, when carbon nanotubes or noble metals are used, the cost is high, so that they are not suitable for disposable applications.

JP 2002-55076 A Japanese Patent No. 3885121 Japanese Patent No. 6159564

  The present invention has been made in view of the above problems, and has an electrode chip for an electrochemical sensor that can measure a plurality of chemical substances while improving the measurement accuracy while having a carbon electrode obtained at a relatively low cost. (Hereinafter simply referred to as an electrode chip) and a method for manufacturing the same.

In order to solve the above problem, the invention according to claim 1 is an electrode chip for an electrochemical sensor,
The electrode tip comprises an insulating support and one or more electrodes including a working electrode,
The at least one electrode protrudes from the support and is made of a base made of a conductive surface, and at least a part of the surface of the base is covered with a protective layer made of a carbon film, The thickness is 1 μm or more,
A catalyst is applied to at least a part of the surface of the protective layer.
The electrode chip is characterized by this.

In the invention according to claim 2, the support includes a sample chamber for holding a sample to be measured.
The one or more electrodes project from the support in the sample chamber;
The electrode chip according to claim 1, wherein the electrode chip is characterized in that

The invention according to claim 3 includes a plurality of sets of the one or more electrodes,
Each set of electrodes comprises the substrate, the protective layer, and the catalyst,
The catalyst is a catalyst different for each of the plurality of sets.
The electrode chip according to claim 1 or 2, wherein the electrode chip is characterized by the above.

  The invention described in claim 4 is the electrode chip manufacturing method according to any one of claims 1 to 3, wherein the method of covering with the protective layer is a plating method. is there.

  In the invention according to claim 5, prior to applying the catalyst to the protective layer, the surface of the protective layer is treated with an oxidizing chemical solution to remove foreign matter and hydrophilic treatment on the surface of the protective layer. The electrode chip manufacturing method according to claim 4, wherein:

  The invention according to claim 6 is characterized in that, prior to applying the catalyst to the protective layer, foreign matter removal and hydrophilic treatment are performed on the surface of the protective layer by electrolytic treatment. This is a chip manufacturing method.

  The invention according to claim 7 is characterized in that a self-assembled monolayer is formed on the surface of the protective layer after removing foreign matter and hydrophilic treatment on the surface of the protective layer. 6. The method for producing an electrode chip as described in 6 above.

  The invention according to claim 8 is characterized in that the method of applying the catalyst is by bringing the protective layer into contact with a solution containing a noble metal, and depositing the noble metal on the protective layer by electrolytic treatment. It is set as the manufacturing method of the electrode chip as described in any one of Claims 4-7.

  The invention described in claim 9 is characterized in that the method of applying the catalyst is by applying a hydrophilic polymer to the protective layer and drying, and then applying an enzyme. The electrode chip manufacturing method according to claim 1 is used.

  According to the present invention, while having a carbon electrode obtained at a relatively low cost, an electrode chip that improves measurement accuracy and enables measurement of a plurality of chemical substances and a method for manufacturing the same are obtained.

(A) The model perspective view which illustrates embodiment of the electrode tip of this invention, (b) The schematic cross section of the surface which cut | disconnected Fig.1 (a) by the A-A 'line. The schematic top view which concerns on the manufacturing method of the electrode chip of this invention, and shows a part of manufacturing process. FIG. 3 is a schematic cross-sectional view showing a part of the process following FIG. 2 in the electrode chip manufacturing method of the present invention. (A) which shows the process of providing the catalyst on the surface of the protective layer, (b), (c), and (d) are AA of (a). 'A schematic cross-sectional view of the surface cut by the line. The schematic sectional drawing which shows the aspect which concerns on embodiment of the electrode tip of this invention, and provides a different catalyst for every some group electrode. The schematic perspective view which shows the whole image of the electrochemical sensor using the electrode chip of this invention.

Hereinafter, an electrode chip for an electrochemical sensor and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings. The same reference numerals are assigned to the same components unless there is a reason for convenience. In each drawing, the thicknesses and ratios of the constituent elements may be exaggerated for ease of viewing, and the number of constituent elements may be reduced. Further, the present invention is not limited to the following embodiments without departing from the gist thereof.

[Configuration of Electrode Tip of the Present Invention]
FIG. 1A is a schematic perspective view illustrating an embodiment of the electrode tip of the present invention, and FIG. 1B is a schematic cross-sectional view of a plane cut along line AA ′ in FIG. It is. The electrode chip 100 has a support 1 made of an insulator as a frame, and the support 1 has a shape with a recessed central portion, and a sample chamber 10 is formed by introducing a sample to be measured into the recess. is there. A voltage or a current is applied to the introduced sample through the electrode 2 fixed by the support 1, and the response is measured.

  The electrode 2 is one or more electrodes (8 electrodes in the drawing) including the working electrode among the working electrode, the counter electrode, and the reference electrode, and at least one of these electrodes (8 electrodes in the drawing) is a sample. It protrudes from the support 1 in the chamber 10. By setting it as the structure which protrudes from the support body 1, the surface area of the electrode 2 can be taken more widely and a measurement precision can be improved. The electrode 2 is outside the support 1 and is connected through the support 1 and a lead electrode 13 that is electrically connected to a measurement unit (see FIG. 6B described later). FIG. 1 shows a case where both the electrode 2 and the extraction electrode 13 are made of a base 3 having a continuous conductive surface.

  In the present application, the support 1 that forms the outer shape of the electrode chip will be described as a representative example in which the support 1 is a rectangular parallelepiped and has a sample chamber 10 in the center as shown in FIG. 1, but is not limited thereto. The sample chamber may not be provided. When the sample chamber is not provided, the electrode 2 directly contacts the sample to be measured separately held. Also, when the sample chamber is provided, the outer shape is not limited to a rectangular parallelepiped shape and may be a sphere or the like, and the sample chamber 10 may be circular or spherical, and the shape according to the measurement target can be freely selected. can do.

  In the electrode 2, at least a part of the surface of the substrate 3 (in FIG. 1, the entire protrusion in the sample chamber 10) is covered with a protective layer 4 made of a carbon film. Further, in the electrode 2, the catalyst 5 is applied to at least a part of the surface of the protective layer 4 (entire surface in FIG. 1).

  The film thickness of the carbon film constituting the protective layer 4 is 1 μm or more. When the thickness is 1 μm or more, a continuous carbon film is formed, which is not a porous film or a film composed of carbon particles like a film formed using carbon paste, but a dense film. Moreover, since it has sufficient thickness, possibility that a pinhole exists is low. Therefore, in the electrode 2 of the electrode chip of the present invention, the possibility that the liquid penetrates the protective layer and comes into contact with the substrate to affect the electrochemical characteristics becomes extremely low.

  Carbon is electrochemically inert. Therefore, even if the protective layer 4 of the electrode chip of the present invention is brought into contact with a living body or a liquid, it is difficult to cause deterioration. Moreover, since it is stable with respect to a living body, the influence on the living body is small when it is brought into contact with the living body.

  In addition, as described above, the conductivity is high because the film is not a porous film or a film composed of carbon particles but a continuous film. Therefore, the electrochemical sensor using the electrode chip of the present invention is excellent in reliability and can be measured with high accuracy.

  Carbon is a cheaper material than precious metals, and its price fluctuation is small. Therefore, the electrochemical sensor using the electrode chip of the present invention can produce an electrode at a relatively low cost.

  The substrate 3 constituting the electrode 2 only needs to have a conductive surface. For example, a metal such as platinum, gold, titanium, copper, iron, nickel, and aluminum, or a metal layer formed on the surface of an insulator or the like. Can be used. In the electrode chip of the present invention, since the protective layer 4 made of carbon is formed on the base 3, the metal to be the base 3 can easily form an alloy with carbon in consideration of adhesion to the protective layer 4. And a metal containing titanium.

  The substrate 3 can also have various shapes. In the case where the substrate 3 has a flat plate shape, the two or more electrodes may be arranged in parallel to each other or may be arranged to be inclined with respect to each other. The base 3 may be, for example, a coil shape, a leaf spring shape, or a cone shape. These can be selected according to the purpose. In addition, when it is set as a coil shape, you may serve as the spring.

  On the other hand, although the extraction electrode 13 is disposed at the bottom of the electrode chip 100 in FIG. 1, it may be disposed on the side surface, and these can be freely selected as necessary. Further, the extraction electrode 13 may be configured not to protrude from the support 1 as long as it can be electrically connected to the measurement unit (see FIG. 6).

  The support 1 is preferably a material that has electrical insulating properties, does not transmit the sample liquid, and does not corrode or break due to the sample liquid. For example, medical plastic or ceramic can be used.

The protective layer 4 is preferably formed by a plating method. For example, it is possible to use a carbon plating technique that is implemented by I'M Sep Co., Ltd. using molten salt electrolysis. This technology uses a anodic oxidation reaction of carbide ions (C ² ₂ ⁻ ) added to a molten salt such as chloride to form a very dense carbon film on the surface of the material to be treated as an anode. is there. These are detailed in Japanese Patent No. 5112010.

  Moreover, the formation of the protective layer 4 made of carbon by plating can form the protective layer 4 uniformly on the side walls of the electrode. That is, this method has an advantage that the surface of the substrate 3 is not exposed by being completely covered with the protective film 4.

  Therefore, according to the plating method, the protective layer 4 can be easily formed to a uniform thickness and a dense film can be formed even on the substrate 3 having a complicated shape such as a three-dimensional shape. The influence on the substrate 3 can be reduced, and the electrode 2 can be formed at a relatively low production cost.

  In the electrode chip of the present invention, in order to further improve the sensitivity of the sensor, the catalyst 5 is applied to the surface of the protective layer 4 (see FIG. 1B). Prior to applying the catalyst, it is necessary to remove (clean) the foreign matter on the surface of the protective layer 4 and to perform hydrophilic treatment on the surface of the protective layer 4 so as not to repel the surface of the protective layer 4 when applying the catalyst. . The method of cleaning the surface of the protective layer 4, the hydrophilic treatment, and the method of applying the catalyst will be described in the electrode chip manufacturing method of the present invention described later.

  As described above, in the electrode chip of the present invention, since the protective layer 4 protects the base 3, the cleaning liquid or the like does not adhere to the base 3 and is not damaged. Accordingly, the surface of the protective layer 4 can be cleaned and the catalyst can be applied, so that the measurement accuracy can be improved.

In the electrode chip of the present invention, a plurality of sets of one or more electrodes including the working electrode among the working electrode, the counter electrode, and the reference electrode are provided, and at least one of the electrodes of each set includes a substrate, a protective layer, and a catalyst. It is possible to measure a plurality of chemical substances by providing different catalysts for a plurality of sets.

[Method for Manufacturing Electrode Chip of the Present Invention]
The electrode tip of the present invention can be manufactured, for example, by sequentially performing the following steps.

(First step)
In FIG. 2A, in order to obtain the electrode 2 and the extraction electrode 13 (both see FIG. 1), the material 3 made of metal is etched to form the portion 3 ′ serving as the base and the portion 13 ′ serving as the extraction electrode. Formed.

  The material is plate-shaped in FIG. 2 (a), but may be other shapes such as a rod as required. Further, the processing method may be cutting, chemical etching, blasting, laser processing, or a combination thereof.

  In FIG. 2, in order to facilitate handling in the subsequent process, the process proceeds to the next process while leaving the part 16 ′ serving as the support part. The portion 16 ′ serving as the support portion may be removed from the portion 13 ′ serving as the extraction electrode, and the process may proceed to the next process.

(Second step)
FIG. 2B shows a unit cut out from the form shown in FIG. 2A in order to form the electrode 2 and the extraction electrode 13. Carbon plating is performed on the base 3 which is a part of the base 3, and as shown in FIG.

(Third step)
Subsequently, the form 413 shown in FIG. 2C is fixed to the support 1 as shown in FIG. After heating the organic resin used as the material of the support 1 at a high temperature to impart fluidity, the form 413 is fixed to the mold, and the organic resin is injected and filled into the mold. The form in which the form 413 is supported by the support 1 can be obtained by removing the mold after the resin has cooled and hardened.

  At the time of the injection molding, an organic resin as a material of the support 1 is prevented from adhering to the portion where the protective layer 4 is formed and the extraction electrode 13. Further, the mold is provided with a shape for providing a concave shape to be the sample chamber 10 in the support 1.

  After obtaining the form of FIG. 3A, the form of FIG. 3B is obtained by cutting and removing the support 16. Further, if necessary, the process may proceed to the next process while holding the support portion 16, and may be cut and removed when it becomes unnecessary.

(4th process)
Next, although not shown, the surface of the protective layer 4 is cleaned and hydrophilized. An oxidative liquid is introduced into a recess that is a sample chamber provided in the support 1, and the surface of the protective layer 4 is immersed and washed. In this method, the foreign matter adhering to the surface of the protective layer 4 is oxidized and removed. Examples of the oxidizing liquid include hydrogen peroxide and nitric acid.

  There is also a method of generating a gas on the surface of the protective layer 4 by electrolytic treatment to perform surface cleaning and hydrophilization treatment. For example, sulfuric acid is introduced as an electrolytic solution, a counter electrode made of platinum is inserted therein, and applied so that the potential of the protective layer 4 serving as the working electrode becomes a voltage exceeding the oxygen overvoltage or hydrogen overvoltage.

(5th process)
There are various methods for applying a catalyst to the surface of the protective layer 4. For example, an electrolytic solution in which chloroplatinic acid is dissolved to apply platinum is used, and the platinum catalyst is deposited by performing electrolytic treatment using the protective layer 4 as a cathode. And a method of imparting a catalyst by supporting an enzyme, and a method of forming a self-assembled monolayer before these can be employed in combination.

  FIG. 4 shows a process of applying the catalyst 5 to the surface of the protective layer 4, and FIG. 4 (a) shows the cleaning of the surface of the protective layer 4 in the region B surrounded by a dotted ellipse in FIG. 3 (b). It is a model perspective view after performing a hydrophilic treatment. 4B is a schematic cross-sectional view of the surface of FIG. 4A cut along the line CC ′, and FIGS. 4C and 4D show a form in which a catalyst is applied to the surface of the protective layer 4. It is a schematic cross section. Thus, either the form of the catalyst 5 ′ applied to a part of the surface of the protective layer 4 or the form of the catalyst 5 applied to the entire surface may be used, and considering the cost merit, FIG. The form of catalyst 5 ′ applied to a part is desirable.

  FIG. 5 is a schematic cross-sectional view showing a mode in which different catalysts are applied to a plurality of sets of electrodes in order to enable measurement of a plurality of chemical substances. A plurality of chemical substances can be measured by applying different catalysts to the protective layers 4a to 4d of the multi-electrode having a plurality of sets of electrodes. For example, as shown in FIG. 5, different catalysts can be applied by using different electrolyte cells 7 a to 7 d and different solutions for each electrode. Or it becomes possible to give a different catalyst by making the glass fiber etc. which hold | maintained electrolyte solution contact each electrode.

[Electrochemical sensor using the electrode chip of the present invention]
FIG. 6 shows an overall image of an electrochemical sensor using the electrode chip of the present invention. In the electrochemical sensor 500, the electrode chip 100 is installed so that the extraction electrode 13 is electrically connected to the extraction electrode 23 provided in the measurement unit 200, and an electric signal from the electrode chip 100 is input to perform measurement. The sample in the sample chamber of the electrode tip 100 is analyzed by measuring and analyzing with the unit 200. The electrode tip 100 can be easily detached from the measuring unit 200 and can be freely replaced. That is, the electrode tip 100 can be made disposable as the “sample part”.

  Hereinafter, specific examples for producing an electrochemical sensor will be described.

(A) Processing of Metal Material A stainless steel (SUS304) plate having a thickness of 0.3 mm was processed to obtain a processed shape made of metal as shown in FIG. Specifically, this processing was performed by the following method. First, a photosensitive etching resist was applied to both surfaces of a stainless steel plate. These resist layers were subjected to pattern exposure and developed to form resist patterns on both surfaces of the stainless steel plate. Subsequently, stainless steel was etched using these resist patterns as an etching mask. As an etchant, a ferric chloride solution was used. Then, the processed shape of FIG. 2A was obtained by peeling off the resist pattern. Next, the processed shape of FIG. 2 (a) was cut and cut into units as shown in FIG. 2 (b).

(B) Formation of Protective Layer Next, a continuous film made of carbon having a thickness of 3 μm is formed as a protective layer 4 on the portion of the base 3 in FIG. 2B by plating, as shown in FIG. Form 413 was adopted. Specifically, the protective layer 4 was formed by immersing a portion of the substrate 3 in molten salt containing calcium carbide (LiCl—KCl—CaCl ₂ : 500 ° C.) and performing anodic polarization.

(C) Temporary Arrangement of Electrode and Fixation to Support Next, a plurality of forms 413 shown in FIG. 2C in which the protective layer 4 is formed on the base 3 are disposed in a cavity of a mold (not shown). At this time, the region not covered with the protective layer 4 is covered with the support 1 and arranged outside the mold so that the support 1 does not adhere to the region covered with the protective layer 4 or the extraction electrode 13. The cross-sectional shape shown in FIG. For simplicity, only one form 413 is shown. Further, the support portion 16 was cut by irradiating with a laser beam to obtain a cross-sectional shape of FIG.

(D) Surface cleaning and hydrophilization treatment Next, 2 mol / L sulfuric acid is introduced into the sample chamber of the support 1 as an electrolytic solution, and a counter electrode made of platinum is inserted so as not to contact the working electrode. Was connected to a constant-potential power supply device, and a potential of 1.6 V vs Ag / AgCl was applied to the working electrode and left for 1 minute. As a result, the foreign matter on the protective layer 4 was removed and water repelling disappeared, and thus the cleaning and hydrophilization treatment was completed.

(E) Catalyst application Next, 0.1 g / L of chloroplatinic acid aqueous solution is introduced into the sample chamber of the support 1, and the electrode made of platinum is used as an anode and the working electrode is used as a cathode for 10 seconds at 1 A / cm ^2. Processed. By this treatment, the electrode tip of the present invention provided with a platinum catalyst was produced.

DESCRIPTION OF SYMBOLS 100 ... Electrode chip 1 ... Support body 2 ... Electrode 3 ... Base | substrate 3 '... Base part 4 ... Protective layer 4a, 4b 4c, 4d ... protective layer 5 '... catalyst 5 ... catalysts 7a, 7b, 7c, 7d ... electrolyte cell 10 ... sample chamber 13 ... drawer Electrode 13 ′... Part 16 serving as extraction electrode... Supporting part 16 ′... Part 413 serving as support part.・ Measurement unit 500 ... electrochemical sensor

Claims (9)

An electrode chip for an electrochemical sensor,
The electrode tip comprises an insulating support and one or more electrodes including a working electrode,
The at least one electrode protrudes from the support and is made of a base made of a conductive surface, and at least a part of the surface of the base is covered with a protective layer made of a carbon film, The thickness is 1 μm or more,
A catalyst is applied to at least a part of the surface of the protective layer.
An electrode tip characterized by that. The support includes a sample chamber for holding a sample to be measured,
The one or more electrodes project from the support in the sample chamber;
The electrode tip according to claim 1, wherein: A plurality of sets of the one or more electrodes;
Each set of electrodes comprises the substrate, the protective layer, and the catalyst,
The catalyst is a catalyst different for each of the plurality of sets.
The electrode tip according to claim 1 or 2, wherein   The method for manufacturing an electrode chip according to any one of claims 1 to 3, wherein the method of covering with the protective layer is a plating method.   5. The method according to claim 4, wherein, prior to applying the catalyst to the protective layer, the surface of the protective layer is treated with an oxidizing chemical solution, and foreign matter removal and hydrophilic treatment are performed on the surface of the protective layer. Manufacturing method of the electrode tip.   5. The method of manufacturing an electrode tip according to claim 4, wherein, prior to applying the catalyst to the protective layer, foreign matter removal and hydrophilic treatment are performed on the surface of the protective layer by electrolytic treatment.   The method for producing an electrode chip according to claim 5, wherein a self-assembled monolayer is formed on the surface of the protective layer after removing foreign matter on the surface of the protective layer and performing hydrophilic treatment. .   The method for applying the catalyst comprises contacting the protective layer with a solution containing a noble metal, and depositing the noble metal on the protective layer by electrolytic treatment. The manufacturing method of the electrode chip as described in a term.   8. The electrode tip according to claim 4, wherein the catalyst is applied by applying a hydrophilic polymer to the protective layer, drying and applying an enzyme. Production method.

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