Electrode, biosensor, and method for manufacturing electrode

Abstract

This electrode (1) comprises a substrate film (2) and an electroconductive carbon layer (4), in the stated order in a direction toward one side in the thickness direction. The electrode 1 satisfies relationship (1) and relationship (2). Relationship 1: {|(O15 / C15)-(O90 / C90)|} / (O15 / C15) × 100 ≤ 30 Relationship 2: O15 / C15 ≥ 0.15 (In relationship (1) and relationship (2), O15 denotes the oxygen atom content measured by X-ray photoelectron spectroscopy in which the photoelectron take-off angle is 15°, and C15 denotes the carbon atom content measured by X-ray photoelectron spectroscopy in which the photoelectron take-off angle is 15°. In relationship (1), O90 denotes the oxygen atom content measured by X-ray photoelectron spectroscopy in which the photoelectron take-off angle is 90°, and C90 denotes the carbon atom content measured by X-ray photoelectron spectroscopy in which the photoelectron take-off angle is 90°.)

Description

Electrode, biosensor, and method for manufacturing electrode

[0001] The present invention relates to an electrode, a biosensor, and a method for manufacturing an electrode, and more particularly to an electrode, a biosensor including the electrode, and a method for manufacturing the electrode.

[0002] Conventionally, carbon electrodes have been used as electrodes for biosensors.

[0003] As such an electrode, for example, an electrode including a substrate and a conductive carbon layer has been proposed (see, for example, Patent Document 1 listed below).

[0004] Japanese Patent Application Laid-Open No. 2021-56205

[0005] Such biosensors are required to have a long shelf life depending on the application, and are also required to have activity against the analyte.

[0006] Furthermore, depending on the application, biosensors are required to be hydrophilic.

[0007] The present invention provides an electrode that is excellent in hydrophilicity, long-term storage stability, and activity toward a test substance, a biosensor including the electrode, and a method for producing the electrode.

[0008] The present invention [1] is an electrode including a substrate film and a conductive carbon layer in this order toward one side in the thickness direction, and satisfying the following formulas (1) and (2): {|(O １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ )×100≦30 (1) O １５ / C １５ ≧0.15 (2) (In the above formula (1) and the above formula (2), O １５ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer, and C １５represents the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer. ９０ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer, and C ９０ indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer.)

[0009] The present invention [2] includes the electrode according to the above [1], wherein the water contact angle on one surface in the thickness direction of the electrode is 75° or less.

[0010] The present invention [3] includes a biosensor comprising the electrode according to the above [1] or [2].

[0011] The present invention [4] is a method for manufacturing an electrode according to the above [1] or [2], comprising: a preparation step of preparing a base film; and a disposition step of disposing a conductive carbon layer on one side in a thickness direction of the base film, wherein the disposition step comprises: a conductive carbon layer disposition step of disposing a conductive carbon layer on one side in the thickness direction of the base film to produce a laminate; and a plasma treatment step of performing a plasma treatment on the one side in the thickness direction of the laminate in the presence of oxygen gas; or a method for manufacturing an electrode comprising: a conductive carbon layer disposition step of disposing a conductive carbon layer on one side in the thickness direction of the base film in the presence of oxygen gas.

[0012] The electrode of the present invention satisfies the following formula (1). Therefore, it has excellent long-term storage properties. １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ ) × 100≦30 (1) (In the above formula (1), O １５ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer, and C １５indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer, and O ９０ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer, and C ９０ indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer.)

[0013] Furthermore, the electrode satisfies the following formula (2). Therefore, the hydrophilicity and activity against the test substance can be improved. １５ / C １５ ≧0.15 (2)

[0014] The biosensor of the present invention includes the electrode of the present invention, and therefore can improve hydrophilicity, long-term storage stability, and activity against a test substance.

[0015] The disposing step in the electrode manufacturing method of the present invention includes a plasma treatment step of performing plasma treatment on one surface in the thickness direction of the conductive carbon layer in the presence of oxygen gas, or a conductive carbon layer disposing step of disposing a conductive carbon layer on one side in the thickness direction of the substrate film in the presence of oxygen gas, thereby making it possible to manufacture an electrode that satisfies the above formula (1) and formula (2).

[0016] FIG. 1 is a cross-sectional schematic diagram of one embodiment of an electrode of the present invention. FIGS. 2A to 2D show a first method of the electrode manufacturing method of the present invention. FIG. 2A shows a preparatory step of preparing a substrate film. FIG. 2B shows a metal underlayer disposing step of disposing a metal underlayer on one thickness-wise surface of the substrate film. FIG. 2C shows a conductive carbon layer disposing step of disposing a conductive carbon layer on one thickness-wise surface of the metal underlayer to produce a laminate. FIG. 2D shows a plasma treatment step of performing plasma treatment on one thickness-wise surface of the laminate in the presence of oxygen gas. FIGS. 3A to 3C show a second method of the electrode manufacturing method of the present invention. FIG. 3A shows a preparatory step of preparing a substrate film. FIG. 3B shows a metal underlayer disposing step of disposing a metal underlayer on one thickness-wise surface of the substrate film. FIG. 3C shows a conductive carbon layer disposing step of disposing a conductive carbon layer on one thickness-wise surface of the metal underlayer in the presence of oxygen gas. 4A to 4C are explanatory diagrams showing the distribution of the amount of oxygen-containing functional groups in the thickness direction of the conductive carbon layer using shading. Fig. 4A shows the distribution of the amount of oxygen-containing functional groups in the conductive carbon layer when the amount of oxygen-containing functional groups in the shallow region is extremely greater than the amount of oxygen-containing functional groups in the deep region, and the difference is extremely large. Fig. 4B shows the distribution of the amount of oxygen-containing functional groups in the conductive carbon layer when the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small, but the amount of oxygen-containing functional groups in the shallow region is small. Fig. 4C shows the distribution of the amount of oxygen-containing functional groups in the conductive carbon layer when the amount of oxygen-containing functional groups in the shallow region is large and the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small.

[0017] An embodiment of the electrode of the present invention will be described with reference to FIG.

[0018] In Figure 1, the up-down direction of the paper surface is the up-down direction (thickness direction). The upper side of the paper surface is the upper side (one side in the thickness direction). The lower side of the paper surface is the lower side (the other side in the thickness direction). The left-right direction and the depth direction of the paper surface are surface directions perpendicular to the up-down direction. Specifically, they conform to the directional arrows in each figure.

[0019] 1, the electrode 1 has a film shape (including a sheet shape) with a predetermined thickness. The electrode 1 extends in a plane direction perpendicular to the thickness direction. The electrode 1 has a flat upper surface and a flat lower surface.

[0020] The electrode 1 includes, in this order toward one side in the thickness direction, a base film 2, a metal base layer 3, and a conductive carbon layer 4. Specifically, the electrode 1 includes the base film 2, the metal base layer 3 disposed directly on the upper surface (one surface in the thickness direction) of the base film 2, and the conductive carbon layer 4 disposed directly on the upper surface (one surface in the thickness direction) of the metal base layer 3. The electrode 1 preferably includes the base film 2, the metal base layer 3, and the conductive carbon layer 4.

[0021] From the viewpoint of ease of handling, the thickness of the electrode 1 is, for example, 10 μm to 1000 μm, preferably 25 μm to 500 μm, more preferably 50 μm to 250 μm, even more preferably 100 μm to 225 μm, and particularly preferably 150 μm to 200 μm.

[0022] <Base Film> The base film 2 has a film shape and is the bottom layer of the electrode 1.

[0023] Examples of materials for the base film 2 include resins, ceramics, and metals. From the viewpoint of flexibility, resins are preferred as materials for the base film 2. In other words, the base film 2 is preferably a resin film.

[0024] Examples of resins include polyester resins, (meth)acrylic resins, olefin resins, polycarbonate resins, polyethersulfone resins, polyarylate resins, melamine resins, polyamide resins, polyimide resins, cellulose resins, and polystyrene resins. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Examples of (meth)acrylic resins include polymethyl methacrylate. Examples of olefin resins include polyethylene, polypropylene, and cycloolefin polymers. Examples of cellulose resins include triacetyl cellulose.

[0025] The resin is preferably a polyester resin, and more preferably polyethylene terephthalate.

[0026] The resins can be used alone or in combination of two or more.

[0027] The thickness of the substrate film 2 is obtained by subtracting the thickness (nm) of the metal underlayer 3 and the thickness (nm) of the conductive carbon layer 4 from the thickness (μm) of the electrode 1 described above, and is, for example, 10 μm to 1000 μm, preferably 25 μm to 500 μm, more preferably 50 μm to 250 μm, even more preferably 100 μm to 225 μm, and particularly preferably 150 μm to 200 μm.

[0028] The thickness of the base film 2 can be measured using a dial gauge (manufactured by PEACOCK, "DG-205").

[0029] <Metallic Underlayer> The metallic underlayer 3 assists the conductivity of the conductive carbon layer 4 .

[0030] The metal underlayer 3 is disposed over the entire upper surface of the substrate film 2 so as to be in contact with the upper surface of the substrate film 2. The metal underlayer 3 is disposed between the substrate film 2 and the conductive carbon layer 4.

[0031] The material of the metal underlayer 3 is a metal. Examples of metals include titanium, tantalum, chromium, molybdenum, tungsten, and niobium. Niobium is preferably used as the material of the metal underlayer 3 from the viewpoint of improving activity with respect to the test substance (described later). In other words, the metal underlayer 3 is preferably a niobium layer.

[0032] The material for the metal underlayer 3 can be used alone or in combination of two or more kinds.

[0033] The metal underlayer 3 is formed by sputtering, as will be described in detail later, that is, the metal underlayer 3 is preferably a sputtered layer.

[0034] The thickness of the metal underlayer 3 is, from the viewpoint of productivity by sputtering, for example, 1 nm to 200 nm, preferably 3 nm to 100 nm, and more preferably 4 nm to 80 nm; from the viewpoint of achieving both productivity and conductivity, it is even more preferably 5 nm to 50 nm, particularly preferably 7 nm to 48 nm, or even 9 nm to 45 nm; and from the viewpoint of further improving productivity and conductivity, it is even more preferably 10 nm to 40 nm, even more preferably 11 nm to 39 nm, or even more preferably 13 nm to 30 nm.

[0035] Specifically, from the viewpoint of reducing the surface resistance of the electrode 1, the thickness of the metal underlayer 3 is, for example, 1 nm or more, preferably 3 nm or more, more preferably 4 nm or more, even more preferably 5 nm or more, particularly preferably 7 nm or more, even 9 nm or more, even 10 nm or more, even 11 nm or more, or even 13 nm or more. From the viewpoint of improving adhesion and suppressing the occurrence of cracks, the thickness is, for example, 200 nm or less, preferably 100 nm or less, more preferably 80 nm or less, even more preferably 50 nm or less, particularly preferably 48 nm or less, even 45 nm or less, even 40 nm or less, even 39 nm or less, or even 30 nm or less.

[0036] <Conductive Carbon Layer> The conductive carbon layer 4 has a film shape. The conductive carbon layer 4 is disposed on the entire upper surface of the metal base layer 3 so as to be in contact with the upper surface of the metal base layer 3. The conductive carbon layer 4 is the uppermost layer of the electrode 1.

[0037] The conductive carbon layer 4 is, for example, sp ２ Bonds and sp ３ That is, the conductive carbon layer 4 has, for example, a graphite structure and a diamond structure, which can improve the conductivity of the conductive carbon layer 4 and can also improve the activity of the conductive carbon layer 4 with respect to a test substance (described later).

[0038] sp ３ Number of bonded atoms and sp ２ sp for the sum of the number of atoms bonded ３ The ratio of the number of bonded atoms (sp ３ / sp ３ +sp ２ ) is, for example, 0.10 to 0.90, preferably 0.20 to 0.50, more preferably 0.25 to 0.45 from the viewpoint of productivity, and even more preferably 0.30 to 0.40 from the viewpoint of electrochemical properties.

[0039] The above ratio is determined by measuring one surface of the conductive carbon layer 4 in the thickness direction by X-ray photoelectron spectroscopy. ２ Bond peak intensity and sp ３ It can be calculated based on the peak intensity of the binding.

[0040] The conductive carbon layer 4 has a functional group containing oxygen.

[0041] As will be described in detail later, the plasma treatment imparts oxygen-containing functional groups to the conductive carbon layer 4. Note that the conductive carbon layer 4 may have oxygen-containing functional groups even before the plasma treatment is performed, but by performing the plasma treatment, it is possible to further impart oxygen-containing functional groups to the conductive carbon layer 4.

[0042] Examples of oxygen-containing functional groups include ester groups, ether groups, hydroxyl groups, and carbonyl groups.

[0043] The conductive carbon layer 4 is formed by a sputtering method, which will be described in detail later. That is, the conductive carbon layer 4 is preferably a sputtered layer. One surface in the thickness direction of the conductive carbon layer 4 is a plasma-treated surface.

[0044] The thickness of the conductive carbon layer 4 is, from the viewpoint of productivity, for example, 1.0 nm to 20 nm, preferably 2.0 nm to 17 nm, and more preferably 2.5 nm to 15 nm; from the viewpoint of achieving both productivity and conductivity, it is still more preferably 3.0 nm to 13 nm, particularly preferably 3.5 nm to 11 nm, furthermore preferably 4.0 nm to 9.0 nm, or even more preferably 4.5 nm to 7.0 nm.

[0045] Specifically, from the viewpoint of improving the performance of the electrode 1, the thickness of the conductive carbon layer 4 is, for example, 1.0 nm or more, preferably 2.0 nm or more, more preferably 2.5 nm or more, even more preferably 3.0 nm or more, particularly preferably 3.5 nm or more, further 4.0 nm or more, and even 4.5 nm or more; and from the viewpoint of ensuring adhesion to the metal underlayer 3, the thickness is, for example, 20 nm or less, preferably 17 nm or less, more preferably 15 nm or less, even more preferably 13 nm or less, particularly preferably 11 nm or less, further 9.0 nm or less, and even 7.0 nm or less.

[0046] The electrode 1 satisfies the following formula (1): {|(O １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ ) × 100≦30 (1) (In the above formula (1), O １５ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer 4, and C １５ indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer 4, and O ９０represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer 4, and C ９０ indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer 4.

[0047] In other words, "{|(O １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ ) x 100" is 30 or less.

[0048] If the electrode 1 satisfies the above formula (1), the long-term storage property can be improved.

[0049] On the other hand, if the electrode 1 does not satisfy the above formula (1), the long-term storage stability will be reduced.

[0050] "{|(O １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ ) × 100" is preferably 20 or less, more preferably 15 or less, even more preferably 10 or less, and particularly preferably 5 or less.

[0051] The electrode also satisfies the following formula (2): １５ / C １５ ≧0.15 (2)

[0052] That is, the carbon atom content (C １５ ) relative to one surface in the thickness direction of the conductive carbon layer 4 by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15°. １５ ) ratio (O １５ / C １５ ) is 0.15 or more. This can improve hydrophilicity and activity against a test substance (described later).

[0053] Ratio (O１５ / C １５ ) is preferably 0.15 or more, more preferably 0.18 or more, even more preferably 0.20 or more, from the viewpoint of improving hydrophilicity and activity against a test substance (described later), and is, for example, 0.35 or less, preferably 0.30 or less, more preferably 0.28 or less, even more preferably 0.24 or less, from the viewpoint of improving activity against a test substance (described later).

[0054] The carbon atom content (C ９０ ) relative to one surface in the thickness direction of the conductive carbon layer 4 by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90°. ９０ ) ratio (O ９０ / C ９０ ) is preferably in the ratio (O １５ / C １５ ) is smaller than

[0055] Ratio (O ９０ / C ９０ ) is, for example, 0.10 to 0.35, preferably 0.15 to 0.30, more preferably 0.17 to 0.28, even more preferably 0.18 to 0.25, and particularly preferably 0.19 to 0.21.

[0056] In detail, the ratio (O ９０ / C ９０ ) is, from the viewpoint of improving the activity against a test substance (described later), for example, 0.10 or more, preferably 0.15 or more, more preferably 0.17 or more, even more preferably 0.18 or more, and particularly preferably 0.19 or more, and from the viewpoint of improving the activity against a test substance (described later), for example, 0.35 or less, preferably 0.30 or less, more preferably 0.28 or less, even more preferably 0.25 or less, and particularly preferably 0.21 or less.

[0057] The above "O １５ "," "C １５ "," "O ９０ " and "C ９０" is adjusted by adjusting the plasma treatment conditions (e.g., oxygen concentration, oxygen gas pressure, plasma generation method, discharge power, discharge voltage, and plasma time) in the plasma treatment step in the first method described later, or the conditions (film formation pressure, discharge power, volume fraction of oxygen gas) in the second method described later.

[0058] The measurement conditions for X-ray photoelectron spectroscopy will be described in detail in the examples below.

[0059] The water contact angle of one surface in the thickness direction of the electrode 1 (specifically, one surface in the thickness direction of the conductive carbon layer 4) is, from the viewpoint of hydrophilicity, for example, 75° or less, preferably 60° or less, more preferably 50° or less, even more preferably 40° or less, particularly preferably 30° or less, and is usually 0° or more.

[0060] The conditions for measuring the water contact angle will be described in detail in the examples below.

[0061] <Electrode Manufacturing Method> A first method for manufacturing the electrode 1 will be described with reference to FIGS. 2A to 2D.

[0062] The manufacturing method of the electrode 1 includes a preparation step of preparing a substrate film 2, a metal underlayer arrangement step of arranging a metal underlayer 3 on one surface in the thickness direction of the substrate film 2, and an arrangement step of arranging a conductive carbon layer 4 on one surface in the thickness direction of the metal underlayer 3.

[0063] The disposing step includes a conductive carbon layer disposing step of disposing a conductive carbon layer 4 on one thickness-wise surface of the metal underlayer 3 to produce the laminate 10, and a plasma treatment step of performing a plasma treatment on one thickness-wise surface of the laminate 10 in the presence of oxygen gas. This method is preferably carried out using a roll-to-roll system. In such a case, the conveying speed is, for example, 0.1 m / min to 20.0 m / min, preferably 0.5 m / min to 10.0 m / min, and more preferably 1.0 m / min to 3.0 m / min.

[0064] [Preparation Step] In the preparation step, as shown in FIG. 2A, a base film 2 is prepared.

[0065] [Metallic Underlayer Arranging Step] In the metallic underlayer arranging step, as shown in FIG. 2B , a metallic underlayer 3 is arranged on one surface of the substrate film 2 in the thickness direction.

[0066] The metal underlayer 3 can be formed by, for example, a dry method or a wet method. The metal underlayer 3 is preferably formed by a dry method.

[0067] Examples of dry methods include PVD (physical vapor deposition) and CVD (chemical vapor deposition). Preferably, the dry method is PVD. Examples of PVD methods include sputtering (e.g., magnetron sputtering (magnetron DC discharge or magnetron DC pulse discharge)), vacuum deposition, laser deposition, and ion plating. Preferably, the PVD method is sputtering.

[0068] In the sputtering method, a target (material for the metal underlayer 3) and the substrate film 2 are placed facing each other in a vacuum chamber. Next, sputtering gas is supplied and a voltage is applied from a power source, which accelerates gas ions and irradiates them onto the target, thereby ejecting the target material from the target surface. The target material is then deposited on the surface (one surface in the thickness direction) of the substrate film 2, forming the metal underlayer 3.

[0069] The sputtering gas may be, for example, an inert gas (eg, argon gas).

[0070] The film formation pressure is, for example, 0.05 Pa to 1.00 Pa, preferably 0.10 Pa to 0.50 Pa, and more preferably 0.15 Pa to 0.30 Pa.

[0071] The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source, or may be a combination of these.

[0072] The discharge power is, for example, 1.0 W / cm ２ ~40.0 W / cm ２ , preferably 2.0 W / cm ２ ~20.0 W / cm ２, more preferably 2.5 W / cm ２ ~10.0 W / cm ２ , more preferably 3.0 W / cm ２ ~5.0 W / cm ２ is.

[0073] The temperature of the substrate film 2 (film formation temperature) is, for example, -10°C to 200°C, preferably 20°C to 100°C, and more preferably 30°C to 60°C.

[0074] As a result, the metal underlayer 3 is disposed on one surface of the substrate film 2 in the thickness direction.

[0075] 2C , in the conductive carbon layer arranging step, a conductive carbon layer 4 is arranged on one surface in the thickness direction of the metal base layer 3 to produce the laminate 10. In other words, in the conductive carbon layer arranging step, a conductive carbon layer 4 is arranged on one side in the thickness direction of the base film 2 to produce the laminate 10.

[0076] The method for forming the conductive carbon layer 4 is the same as the method for forming the metal underlayer 3. The method for forming the conductive carbon layer 4 is preferably a sputtering method (for example, magnetron sputtering (magnetron DC discharge or magnetron DC pulse discharge)).

[0077] In the sputtering method, sintered carbon is selected as the target.

[0078] The sputtering gas may be, for example, an inert gas (e.g., argon gas). In addition, the sputtering method does not use a reactive gas (e.g., oxygen gas). In other words, the sputtering method is a non-reactive sputtering method.

[0079] The film formation pressure is, for example, 0.05 Pa to 1.00 Pa, preferably 0.10 Pa to 0.50 Pa, and more preferably 0.15 Pa to 0.30 Pa.

[0080] The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source, or may be a combination of these.

[0081] The discharge power is, for example, 0.5 W / cm ２ ~30.0 W / cm ２ , preferably 1.0 W / cm ２ ~20.0 W / cm ２ , more preferably 5.0 W / cm ２ ~10.0 W / cm ２ is.

[0082] The temperature of the substrate film 2 (film formation temperature) is, for example, -10°C to 200°C, preferably 20°C to 100°C, and more preferably 30°C to 60°C.

[0083] In this way, the conductive carbon layer 4 is disposed on one surface in the thickness direction of the metal base layer 3, and the laminate 10 is manufactured.

[0084] [Plasma Treatment Step] In the plasma treatment step, as shown in FIG. 2D, plasma treatment is performed on one surface in the thickness direction of the laminate 10 (specifically, one surface in the thickness direction of the conductive carbon layer 4) in the presence of oxygen gas.

[0085] Specifically, the laminate 10 is transferred into a vacuum chamber, and oxygen is supplied into the vacuum chamber.

[0086] The oxygen concentration in the vacuum chamber is, for example, 50% by volume to 100% by volume, preferably 70% by volume to 100% by volume, and more preferably 90% by volume to 100% by volume. In practice, the oxygen concentration in the vacuum chamber is about 98% by volume.

[0087] A gas other than oxygen (specifically, an inert gas) may be introduced into the vacuum chamber. Examples of the inert gas include argon. The proportion of the gas other than oxygen in the vacuum chamber is the balance of the oxygen in the vacuum chamber, and is, for example, 10% by volume or less.

[0088] The pressure of the oxygen gas in the vacuum chamber is, for example, 0.01 Pa to 2.00 Pa, preferably 0.10 Pa to 1.00 Pa, more preferably 0.40 Pa to 0.80 Pa, and even more preferably 0.50 Pa to 0.70 Pa. The pressure can be adjusted by the amount of oxygen supplied to the vacuum chamber.

[0089] Next, one surface of the laminate 10 in the thickness direction is subjected to plasma treatment.

[0090] Examples of plasma generation methods include an AC plasma generation method and a DC plasma generation method. Examples of AC plasma generation methods include capacitively coupled plasma (CCP), inductively coupled plasma (ICP), and surface acoustic wave plasma (SWP). Examples of DC plasma generation methods include magnetron DC discharge. A preferred plasma generation method is a DC plasma generation method.

[0091] The discharge power is, for example, 1.0 W / cm ２ ~12.0 W / cm ２ , preferably 1.5 W / cm ２ ~10.0 W / cm ２ , more preferably 2.0 W / cm ２ ~6.0 W / cm ２ , more preferably 2.5 W / cm ２ ~4.0 W / cm ２ is.

[0092] The discharge voltage is, for example, 200V to 500V, preferably 300V to 495V, more preferably 400V to 490V, still more preferably 450V to 485V, and particularly preferably 460V to 480V.

[0093] The plasma treatment time is, for example, 0.3 to 60 seconds, preferably 1 to 45 seconds, more preferably 10 to 30 seconds, and even more preferably 20 to 28 seconds.

[0094] In this way, plasma treatment is performed on one surface in the thickness direction of the laminate 10, to produce the electrode 1. In Fig. 2D, the plasma-treated surface is indicated by a thick line.

[0095] A second method for manufacturing the electrode 1 will be described with reference to FIGS. 3A to 3C.

[0096] The manufacturing method of the electrode 1 includes a preparation step of preparing a substrate film 2, a metal underlayer arrangement step of arranging a metal underlayer 3 on one surface in the thickness direction of the substrate film 2, and an arrangement step of arranging a conductive carbon layer 4 on one surface in the thickness direction of the metal underlayer 3.

[0097] The disposing step includes a conductive carbon layer disposing step of disposing the conductive carbon layer 4 on one side in the thickness direction of the substrate film 2 in the presence of oxygen gas.

[0098] [Preparation Step] In the preparation step, as shown in FIG. 3A, the first base film 2 is prepared according to the same procedure as in the first method.

[0099] [Metallic Underlayer Arranging Step] In the metallic underlayer arranging step, as shown in FIG. 3B, the metallic underlayer 3 is arranged on one surface in the thickness direction of the substrate film 2 according to the same procedure as in the first method.

[0100] [Conductive Carbon Layer Arranging Step] In the conductive carbon layer arranging step, as shown in FIG. 3C, a conductive carbon layer 4 is arranged on one side in the thickness direction of the substrate film 2 in the presence of oxygen gas.

[0101] A preferred method for disposing the conductive carbon layer 4 is sputtering.

[0102] In the sputtering method, sintered carbon is selected as the target.

[0103] The sputtering gas may be, for example, an inert gas (e.g., argon gas). The sputtering is performed in the presence of oxygen gas. In other words, the sputtering method is a reactive sputtering method. The volume ratio of the oxygen gas to the total amount of the oxygen gas and the inert gas is 10% by volume to 30% by volume.

[0104] The film formation pressure is, for example, 0.05 Pa to 1.00 Pa, preferably 0.10 Pa to 0.50 Pa, and more preferably 0.15 Pa to 0.30 Pa.

[0105] The power source may be, for example, a DC power source, an AC power source, an MF power source, or an RF power source, or may be a combination of these.

[0106] The discharge power is, for example, 0.5 W / cm ２ ~30.0 W / cm ２ , preferably 1.0 W / cm ２ ~20.0 W / cm ２ , more preferably 5.0 W / cm ２ ~10.0 W / cm ２ is.

[0107] The temperature of the substrate film 2 (film formation temperature) is, for example, -10°C to 200°C, preferably 20°C to 100°C, and more preferably 30°C to 60°C.

[0108] In this way, the conductive carbon layer 4 is disposed on one surface in the thickness direction of the metal underlayer 3, and the electrode 1 is manufactured.

[0109] In the second method, a plasma treatment step can be carried out after the conductive carbon layer disposing step, if necessary. The conditions for the plasma treatment step are the same as those for the first method.

[0110] The electrode 1 satisfies the above formulas (1) and (2), and therefore has improved hydrophilicity, long-term storage stability, and activity against test substances.

[0111] Therefore, the electrode 1 can be suitably used particularly as an electrode in a biosensor, that is, the electrode 1 is preferably a biosensor electrode.

[0112] 2. Biosensor In the following description, a blood glucose sensor will be described in detail as an example of a biosensor. In the blood glucose sensor, the test substance is, for example, a ferrocyanide compound. In the following description, the case where the test substance is a ferrocyanide compound will be described in detail.

[0113] The blood glucose sensor includes an electrode 1 and a reagent layer arranged in this order toward one side in the thickness direction.

[0114] The reagent layer contains an enzyme and a ferricyanide or ferrocyanide compound.

[0115] An example of the enzyme is glucose oxidase.

[0116] Examples of the ferricyanide compound include potassium ferricyanide and sodium ferricyanide. The ferricyanide compound is preferably potassium ferricyanide.

[0117] Examples of ferrocyanide compounds include potassium ferrocyanide and sodium ferrocyanide.

[0118] A method for detecting glucose in blood using a blood glucose sensor will be described in detail below, with the reagent layer containing an enzyme and potassium ferricyanide.

[0119] In this method, blood is first added to one side of the reagent layer in the thickness direction. At this time, glucose in the blood is oxidized by the enzyme in the reagent layer. At this time, the enzyme reduces potassium ferricyanide to potassium ferrocyanide.

[0120] A voltage is then applied to the blood glucose sensor, which causes the potassium ferrocyanide to oxidize and become potassium ferricyanide.

[0121] By measuring the value of the current that flows during the oxidation reaction, glucose in the blood can be indirectly detected.

[0122] The blood glucose sensor includes the electrode 1. Therefore, it has excellent long-term storage stability and activity against test substances.

[0123] 3. Effects and Effects The electrode 1 satisfies the above formula (1). Therefore, it has excellent long-term storage properties. Furthermore, the electrode 1 satisfies the above formula (2). Therefore, it is possible to improve the activity against the test substance (specifically, a ferrocyanide compound).

[0124] Specifically, in X-ray photoelectron spectroscopy, the detection depth decreases when the photoelectron take-off angle with respect to one surface in the thickness direction of the conductive carbon layer 4 is reduced, thereby making it possible to obtain information on a region relatively close to the interface between the conductive carbon layer 4 and air (hereinafter, sometimes referred to as a shallow region).

[0125] On the other hand, in X-ray photoelectron spectroscopy, the detection depth increases when the photoelectron take-off angle with respect to one surface in the thickness direction of the conductive carbon layer 4 is increased, thereby making it possible to obtain information on a region relatively far from the interface between the conductive carbon layer 4 and air (hereinafter, sometimes referred to as a deep region).

[0126] That is, in the above formula (1), "O １５ / C １５ " indicates the ratio of the oxygen atom content to the carbon atom content in the shallow region. ９０ / C ９０ " indicates the ratio of the oxygen atom content to the carbon atom content in the deep region.

[0127] In addition, the ratio of the content of oxygen atoms to the content of carbon atoms (specifically, O １５ / C １５ and O ９０ / C ９０ ) indicates the amount of functional groups containing oxygen in the conductive carbon layer 4. １５ / C １５ A larger value of "O" indicates that the amount of oxygen-containing functional groups is large in the shallow region. １５ / C １５ When " is small, it indicates that the amount of oxygen-containing functional groups is small in the shallow region. １５ / C １５ " is an indicator of the amount of oxygen-containing functional groups in the shallow region. ９０ / C ９０ " is an indicator of the amount of oxygen-containing functional groups in the deep region.

[0128] From the above, the above formula (1) indicates that the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small.

[0129] Next, the relationship between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region and the long-term storage stability will be described in detail.

[0130] The oxygen-containing functional group has a lone electron pair, which allows electron donation and acceptance with ferrocyanide, thereby improving the activity (electron donation and acceptance with the ferrocyanide compound) of the test substance (specifically, the ferrocyanide compound).

[0131] Therefore, the more oxygen-containing functional groups there are at the interface (shallow region) between the conductive carbon layer 4 and air, the more the activity toward the test substance (specifically, ferrocyanide compound) can be improved.

[0132] On the other hand, oxygen-containing functional groups undergo inward rotation within the molecule after a long period of time has passed since the plasma treatment. Specifically, oxygen-containing functional groups in shallow regions rotate toward deeper regions. Also, oxygen-containing functional groups in deep regions rotate toward shallower regions. In other words, after a long period of time has passed since the plasma treatment, the amount of oxygen-containing functional groups in shallow regions and the amount of oxygen-containing functional groups in deep regions are swapped.

[0133] 4A to 4C are explanatory diagrams that schematically show the results of measurement by X-ray photoelectron spectroscopy, and illustrate the distribution of the amount of oxygen-containing functional groups in the thickness direction of the conductive carbon layer 4 using shades of gray.

[0134] FIG. 4A shows a conductive carbon layer 4 in which the amount of oxygen-containing functional groups in the shallow region is much greater than the amount of oxygen-containing functional groups in the deep region, and the difference is extremely large.

[0135] Since the amount of oxygen-containing functional groups is large in the shallow region, the conductive carbon layer 4 (electrode 1) satisfies the above formula (2), and therefore has excellent activity toward ferrocyanide compounds immediately after the plasma treatment.

[0136] On the other hand, since there is a large difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region, the conductive carbon layer 4 (electrode 1) does not satisfy the above formula (1). In such a case, after a long period of time has passed since the plasma treatment, the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region are reversed, the amount of oxygen-containing functional groups in the shallow region decreases, and the activity toward ferrocyanide compounds decreases. As a result, long-term storage stability is reduced.

[0137] FIG. 4B shows the conductive carbon layer 4 in the case where the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small, but the amount of oxygen-containing functional groups in the shallow region is small.

[0138] Since the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small, the above formula (1) is satisfied. Therefore, the activity of electrode 1 toward ferrocyanide compounds remains unchanged even after long-term storage. However, since the amount of oxygen-containing functional groups in the shallow region is small to begin with, the above formula (2) is not satisfied, and both the activity toward the test substance (specifically, the ferrocyanide compound) and hydrophilicity are insufficient.

[0139] In contrast, as shown in FIG. 4C , in the conductive carbon layer 4 of the electrode 1, the amount of oxygen-containing functional groups is large in the shallow region, and the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small.

[0140] Since the amount of oxygen-containing functional groups is large in the shallow region, the conductive carbon layer 4 (electrode 1) satisfies the above formula (2), and therefore has excellent activity with respect to ferrocyanide compounds immediately after the plasma treatment.

[0141] Since the difference between the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region is small, the above formula (1) is satisfied. Therefore, even if a long period of time passes after plasma treatment and the amount of oxygen-containing functional groups in the shallow region and the amount of oxygen-containing functional groups in the deep region are interchanged, the amount of oxygen-containing functional groups in the shallow region does not change significantly. As a result, even after long-term storage, the activity toward ferrocyanide compounds does not decrease significantly. In other words, the long-term storage property is excellent.

[0142] Specifically, the electrode 1 retains activity toward ferrocyanide compounds even after, for example, one day or more, preferably seven days or more, more preferably 14 days or more, even more preferably 100 days or more, particularly preferably one year or more, and most preferably two years or more after the plasma treatment. As a result, when the electrode 1 is used in a biosensor, the usable life of the biosensor can be extended.

[0143] The blood glucose sensor includes the electrode 1. Therefore, the activity of the electrode 1 against the ferrocyanide compound is excellent in long-term storage, and the expiration date can be extended.

[0144] Furthermore, the electrode 1 satisfies the above formula (2), and therefore has excellent hydrophilicity.

[0145] <Modifications> In the modification examples, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modification examples can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and the modification examples can be combined as appropriate.

[0146] In the above description, the electrode 1 includes the base film 2, the metal underlayer 3, and the conductive carbon layer 4 in this order toward one side in the thickness direction, but the electrode 1 does not necessarily have to include the metal underlayer 3. In such a case, the electrode 1 includes the base film 2 and the conductive carbon layer 4 in this order toward one side in the thickness direction. Preferably, the electrode 1 includes the metal underlayer 3 from the viewpoint of improving activity toward ferrocyanide compounds.

[0147] The electrode 1 may also include layers (e.g., a hard coat layer, a gas barrier layer) other than the base film 2, the metal underlayer 3, and the conductive carbon layer 4. Specifically, the electrode 1 may include other layers on the other surface of the base film 2 in the thickness direction, between the base film 2 and the metal underlayer 3, between the metal underlayer 3 and the conductive carbon layer 4, and on one surface of the conductive carbon layer 4 in the thickness direction.

[0148] The hard coat layer is an abrasion protection layer that makes it difficult for scratches to occur on the electrode 1. Specifically, the electrode 1 preferably includes a hard coat layer on one surface and / or the other surface in the thickness direction of the substrate film 2.

[0149] Furthermore, when the electrode 1 includes other layers, the thickness of the substrate film 2 is the thickness (μm) of the electrode 1 minus the thickness (nm) of the metal underlayer 3, the thickness (nm) of the conductive carbon layer 4, and the thicknesses (nm) of the other layers.

[0150] In the above explanation, the ratio (O ９０ / C ９０ ) is the ratio (O １５ / C １５ ), but the ratio (O ９０ / C ９０ ) is the ratio (O １５ / C １５ ) may be larger than

[0151] In the above description, the electrode 1 is described as an electrode of a biosensor, but it is not limited to this and can also be used as an electrode for electrochemical measurement of a ferrocyanide compound as the measurement target, specifically as a working electrode for performing cyclic voltammetry (CV).

[0152] The present invention will be described in more detail below with reference to examples and comparative examples. It should be noted that the present invention is in no way limited to these examples and comparative examples. The specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values ​​(numeric values ​​defined as "equal to or less than") or lower limit values ​​(numeric values ​​defined as "equal to or more than" or "exceeding") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the "Modes for Carrying Out the Invention" above.

[0153] <Electrode Manufacturing> Example 1 (First Method) [Preparation Step] A polyethylene terephthalate film (thickness: 188 μm) was prepared as a substrate film. The following steps were carried out using a roll-to-roll process. A gas barrier layer (Si layer) was formed on one surface of the substrate film in the thickness direction by sputtering.

[0154] [Metal Underlayer Forming Step] A niobium layer (thickness: 20 nm) was formed on one thickness-wise surface of the gas barrier layer by magnetron sputtering (magnetron DC discharge). The magnetron sputtering conditions were as follows: {Conditions} Target: Niobium Sputtering gas: Argon gas Transfer speed: 1.5 m / min Film formation pressure: 0.20 Pa Discharge power: 3.6 W / cm ２ Film forming temperature: 40℃

[0155] [Conductive Carbon Layer Forming Step] A conductive carbon layer (thickness: 5 nm) was formed on one surface of the niobium layer in the thickness direction by magnetron sputtering. The magnetron sputtering conditions were as follows. A laminate was thus produced. {Conditions} Target: Sintered carbon Sputtering gas: Argon gas Transport speed: 1.5 m / min Film formation pressure: 0.20 Pa Discharge power: 7.8 W / cm ２ Film forming temperature: 40℃

[0156] [Plasma Treatment Step] In the presence of oxygen gas, plasma treatment was performed on one surface in the thickness direction of the laminate (specifically, one surface in the thickness direction of the conductive carbon layer) under the following conditions. Thus, an electrode was manufactured. {Conditions} Plasma generation method: magnetron DC discharge Oxygen concentration: 98% by volume Gas: oxygen Oxygen gas pressure: 0.65 Pa Discharge power: 2.6 W / cm ２ Discharge voltage: 476V Plasma time: 24 seconds

[0157] Examples 2 to 6, Comparative Examples 1 and 2 (First Method) Electrodes were manufactured based on the same procedure as in Example 1. However, the conditions for each step were changed according to Table 1. In Comparative Example 2, the plasma treatment step was not performed.

[0158] Example 7 (Second Method) An electrode was manufactured based on the same procedure as in Example 1. However, the conditions for each step were changed according to Table 1. In particular, the conductive carbon layer disposing step was carried out in the presence of oxygen gas under the following conditions. Note that in Example 7, the plasma treatment step was not carried out. {Conditions} Target: Sintered carbon Sputtering gas: Argon gas / oxygen gas = 90 / 20 (v / v) Transport speed: 1.5 m / min Film formation pressure: Total pressure 0.25 Pa Discharge power: 7.8 W / cm ２ Film forming temperature: 40℃

[0159] <Evaluation> [Thickness] The thickness of the metal underlayer and the conductive carbon layer in the electrodes of each Example and Comparative Example were measured by preparing cross-sectional samples for TEM by FIB microsampling and observing the cross-sections using a field emission transmission electron microscope (FE-TEM, manufactured by JOEL, "JEM-2800"). The results are shown in Table 1.

[0160] [X-ray Photoelectron Spectroscopy Measurement] The electrodes of each Example and Comparative Example (within 12 hours after the plasma treatment) were cut into 1 cm x 1 cm pieces to prepare measurement samples. Next, X-ray photoelectron spectroscopy measurements were performed on the measurement samples. Specifically, a wide scan spectrum and a narrow scan spectrum were obtained for one surface in the thickness direction of the measurement sample (the surface of the conductive carbon layer), and the element ratio was calculated from the ratio of the areas of the respective peaks. Other measurement conditions are as follows. The measurements were performed at a photoelectron take-off angle of 15° and a photoelectron take-off angle of 90°. As a result, it was possible to obtain "O １５ "," "C １５ "," "O ９０ " and "C ９０ " and "O １５ / C １５ "," "O ９０ / C ９０ The results are shown in Table 1. {Conditions} X-ray photoelectron spectrometer: KRATOS ULTRA2 manufactured by Shimadzu Corporation X-ray source: Monochrome Al Kα X Ray setting: 700 μm × 300 μm [5 mA, 75 W, Resolution 20] Photoelectron take-off angle: 15 degrees and 90 degrees with respect to the sample surface Charge neutralization conditions: Charge neutralization mechanism used

[0161] [Long-term storage stability of activity against ferrocyanide compounds] Immediately after plasma treatment (specifically, within 12 hours after plasma treatment), the activity against potassium ferrocyanide was evaluated for the electrodes of each example and each comparative example.

[0162] Specifically, a sample electrode with a known electrode area was prepared by attaching an insulating tape with a hole of 2 mm diameter to one side of the conductive carbon layer 4. Cyclic voltammetry (CV) was carried out using this sample electrode as the working electrode. Specifically, 1 M KCl was used as the electrolyte and 1 mM KCl was used as the electrode active material. ４ [Fe(CN) ６The sample electrode was immersed in an aqueous solution containing potassium ferrocyanide. In the CV measurement, the potential was swept from negative to positive in the range of -0.1 to 0.5 V (specifically, the potential was changed in the order of -0.1 V, 0.5 V, and -0.1 V). The potential sweep rate was 0.1 V / s. The CV measurement was performed at 23°C. Three CV measurements were performed. The average value of the ΔEp values ​​obtained three times in the CV measurement was taken as the ΔEp immediately after the plasma treatment. It can be seen that the smaller the ΔEp, the faster the electron transfer rate and the better the activity against potassium ferrocyanide.

[0163] Next, using the same procedure, the activity of the electrodes of each Example and Comparative Example against potassium ferrocyanide was evaluated two weeks after the plasma treatment. The results are shown in Table 1. The absolute value of the rate of change in ΔEp after two weeks from the plasma treatment relative to ΔEp immediately after the plasma treatment is also shown. It can be seen that the smaller the absolute value of the rate of change, the better the long-term storage stability of the activity against ferrocyanide compounds.

[0164] [Hydrophilicity] For each electrode of each Example and Comparative Example, the water contact angle of one surface in the thickness direction of the electrode was measured immediately after the plasma treatment (specifically, within 12 hours after the plasma treatment). The measurement results are shown in Table 1.

[0165] Specifically, the water contact angle was measured by the sessile drop method using a water contact angle measuring device (product name "Dmo-501", manufactured by Kyowa Interface Science Co., Ltd.) in an atmosphere at a temperature of 23°C and a humidity of 30% RH. First, a water droplet of about 2.0 μL was dropped onto the center of one surface of the electrode in the thickness direction. Then, one second after the drop, the angle formed by the tangent line of the adherend surface (one surface of the electrode in the thickness direction) and the end of the dropped water droplet was measured and recorded as the "water contact angle (°)." A smaller "water contact angle (°)" indicates better hydrophilicity.

[0166]

[0167] The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be interpreted as limiting. Modifications of the present invention that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0168] The electrode, biosensor, and electrode manufacturing method of the present invention can be suitably used, for example, in the manufacture of a blood glucose level sensor.

[0169] REFERENCE SIGNS LIST 1 Electrode 2 Base film 4 Conductive carbon layer 10 Laminate

Claims

1. An electrode having a base film and a conductive carbon layer in this order toward one side in the thickness direction, and satisfying the following formulas (1) and (2): {|(O １５ / C １５ )-(O ９０ / C ９０ ) |} / (O １５ / C １５ )×100≦30 (1) O １５ / C １５ ≧0.15 (2) (In the above formula (1) and the above formula (2), O １５ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer, and C １５ represents the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 15° with respect to one surface in the thickness direction of the conductive carbon layer. ９０ represents the content of oxygen atoms measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer, and C ９０ indicates the carbon atom content measured by X-ray photoelectron spectroscopy with a photoelectron take-off angle of 90° with respect to one surface in the thickness direction of the conductive carbon layer.) 2. The electrode according to claim 1, wherein the water contact angle on one surface in the thickness direction of said electrode is 75° or less.

3. A biosensor comprising the electrode according to claim 1 or 2.

4. A method for manufacturing an electrode according to claim 1 or 2, comprising: a preparation step of preparing a base film; and a placement step of placing a conductive carbon layer on one side of the base film in the thickness direction, said placement step comprising: a conductive carbon layer placement step of placing a conductive carbon layer on one side of the base film in the thickness direction to produce a laminate; and a plasma treatment step of performing plasma treatment on one side of the laminate in the thickness direction in the presence of oxygen gas; or a method for manufacturing an electrode comprising: a conductive carbon layer placement step of placing a conductive carbon layer on one side of the base film in the thickness direction in the presence of oxygen gas.

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