JP2002189012A - Platinum electrode for enzyme electrode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a platinum electrode, capable of obtaining an enzyme electrode stable with respect to changes in passage of time and superior in analysis accuracy and reproducibility in which platinum is high close contact and the smoothness of a surface is high, and a method capable of inexpensively manufacturing the platinum electrode with proper productivity. SOLUTION: In the platinum electrode for the enzyme electrode, a copper foil (2), a nickel layer (3), a palladium/nickel layer (4), and a platinum layer (6) are sequentially laminated on an insulating substrate (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a platinum electrode used as an enzyme electrode for detecting a specific substance in a test solution, and is used, for example, for a diabetic patient to measure his or her own blood glucose level at home. The present invention relates to a platinum electrode for an enzyme electrode suitable for a simple blood glucose level measuring device to be used.

[0002]

2. Description of the Related Art As a disposable enzyme electrode for measuring glucose in blood, for example, Japanese Patent Publication No. 6-58338 discloses that a carbon paste containing a resin binder is printed on a lead on which a silver paste is printed and heated. An enzyme electrode which is dried and has a reagent reaction layer formed thereon is described. However, once this enzyme electrode absorbs moisture, the carbon ink dissolves and mixes with the reagent reaction layer formed on it,
It does not have the performance as an enzyme electrode. Therefore, from the viewpoint of productivity, there is an advantage that it can be manufactured at low cost,
There is a strong demand for tightness in order to keep the enzyme electrode under low humidity during distribution, and there are great restrictions on measurement such as the fact that it must be used immediately after opening.

An enzyme electrode using a platinum electrode is also widely used. However, in order to analyze hydrogen peroxide generated by contacting glucose with an enzyme with sufficient accuracy and reproducibility, an electrode area is required. It is necessary to ensure uniformity. As means for that purpose, a method of realizing the patterning with high precision using a ceramic substrate or a glass substrate, and a method of increasing the overall size and reducing the tolerance are general. However, the former method causes an increase in cost and is not preferable for disposable use. On the other hand, the latter method is inexpensive, but has a problem that the patterning accuracy is inferior to the former method. In addition, the final electrode area of the platinum electrode is an area derived from the surface roughness of the platinum surface formed after platinum plating, which is added to the patterned electrode surface. It is difficult to make the electrode area uniform only by patterning. The surface roughness of the platinum electrode is largely determined by surface polishing, soft etching, etc. of the copper foil before patterning, and it is necessary to secure the uniform surface roughness of the platinum electrode by the conventional plating method. Is also difficult.

Further, as described in Japanese Patent No. 2536780, a method of forming a platinum layer on a patterned copper by a method such as platinum plating or the like, by applying a gold plating between copper and platinum, A method of improving the performance is also employed. However, direct plating of platinum on copper as in the former method has a problem in adhesion due to a large potential difference between dissimilar metals. In the latter method, although the adhesion between copper and platinum is improved as compared with the former method, it is not sufficient, and it is not only unstable as an electrode but also expensive. Further, in the above plating method, there is a problem that copper is deposited on the platinum surface with the lapse of time due to a high potential difference, and eventually a copper oxide film or rust is formed and the function as an enzyme electrode cannot be performed. That is, since a current other than the oxidation current of hydrogen peroxide flows, the analysis accuracy and reproducibility required for the enzyme electrode cannot be obtained even if the pattern is formed with high accuracy.

On the other hand, as described in Japanese Patent Application Laid-Open No. 10-339717, there is a method for improving the analysis accuracy and reproducibility by making the surface of a platinum electrode uniform by jet scrubbing. However, in this method, since the fine particles are sprayed at a high water pressure, there is a problem that the fine particles are buried in the surface of the platinum electrode surface and hinder the function as a platinum electrode. Furthermore,
Since crater-like recesses are formed everywhere on the surface of the platinum electrode, when viewed microscopically, they act in a direction of roughening rather than smoothness. In addition, from the viewpoint of productivity, it is necessary to frequently replenish fine particles for spraying with high water pressure, and furthermore, it is necessary to uniformly perform jet scrub processing on the entire substrate on which a plurality of electrodes are arranged. And other difficulties.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has high platinum adhesion.
An object of the present invention is to provide a platinum electrode which is stable over time, has a high surface smoothness, and provides an enzyme electrode having excellent analysis accuracy and reproducibility. Another object of the present invention is to provide a method for producing the platinum electrode for an enzyme electrode at low cost and with high productivity.

[0007]

In order to achieve the above object, the present invention is characterized in that a copper foil, a nickel layer, a palladium nickel layer and a platinum layer are sequentially laminated on an insulating substrate. The present invention provides a platinum electrode for an enzyme electrode.

The present invention also provides a platinum electrode for an enzyme electrode as described above, wherein a strike layer of gold particles or nickel particles is interposed between the palladium nickel layer and the platinum layer.

In addition, a copper foil is formed on an insulating substrate, a predetermined circuit is patterned, and a nickel layer, a palladium nickel layer and a platinum layer are sequentially laminated thereon by plating. Provided is a method for manufacturing a platinum electrode.

Further, a copper foil is formed on an insulating substrate, a predetermined circuit is patterned, a nickel layer and a palladium nickel layer are sequentially formed thereon by a plating method, and gold particles or palladium layers are formed thereon by a strike treatment. A method for producing a platinum electrode for an enzyme electrode, comprising forming a platinum layer by plating after fixing a nickel particle layer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a platinum electrode for an enzyme electrode according to the present invention (hereinafter simply referred to as "platinum electrode") will be described below with reference to the drawings.

A platinum electrode according to the present invention is formed on an insulating substrate 1 and, as shown in a sectional view in FIG. 1, a nickel layer is formed on a copper foil 2 which is patterned into a predetermined circuit. 3, a palladium nickel layer 4 and a platinum layer 6 are laminated. Since each of these metal layers can be easily formed by an extremely common plating method, the productivity is excellent. As the insulating substrate 1, an inexpensive glass epoxy can be used, and if necessary, a ceramic substrate or a glass substrate may be used.

According to the present invention, by providing the nickel layer 3 on the copper foil 2, even if the surface roughness of the copper foil 2 is such that it can be obtained in a regular polishing step for a normal electric circuit board. The nickel layer 3 compensates for the flatness, so that the surface of the platinum layer 6 as the uppermost layer can have high smoothness. For example, even if the distance between electrodes when a pattern is formed by a normal etching process has a dimensional tolerance of 160 ± 30 μm, sufficient analysis accuracy can be obtained if smoothing by the nickel layer 3 is achieved. Become.

Furthermore, by interposing the nickel layer 3,
The palladium nickel layer 4 and the platinum layer 6 formed thereon can be made thinner, and cost reduction can be realized while using a noble metal. For example, Patent No. 253678
Although it is possible to form a thick gold layer by gold plating and make the platinum surface smooth as described in Japanese Patent Publication No. 0, production costs increase from a disposable viewpoint, which is not practical. Also, from the viewpoint of adhesion, it is insufficient as an electrode.

Further, by interposing the nickel layer 3,
It is possible to prevent copper from being eluted into the platinum layer 6, and to provide an enzyme electrode that is stable over time.

In the platinum electrode according to the present invention, the palladium nickel layer 4 is interposed on the nickel layer 3 so that the nickel layer 3 and the palladium nickel layer 4
In addition, excellent adhesion is obtained between the palladium nickel layer 4 and the platinum layer 6, and as a result, a platinum electrode having strong adhesion from the copper foil 2 to the platinum layer 6 can be realized.

In the platinum electrode according to the present invention,
As shown in FIG. 2 as a cross-sectional view, it is preferable that gold particles or nickel particles 5 formed by a strike process are interposed between the palladium nickel layer 4 and the platinum layer 6. When forming gold particles or nickel particles by gold strike or nickel strike, it is preferable to apply a voltage of 3 V for one minute. Thereby, the palladium nickel layer 4 and the platinum layer 6 are more firmly adhered. Another effect of the gold strike process is that platinum precipitates from the gold particles that serve as its nucleus during the platinum plating process, so that if the gold particles are uniformly fixed in advance, the electrode surface with more uniform smoothness can be obtained. Can be obtained.

By adopting such a laminated structure, a smoothness approximately twice as high as that obtained by providing the platinum layer 6 on the copper foil 2 can be obtained as shown in the following embodiments. .

In the above-mentioned platinum electrode according to the present invention,
Although the thickness of each metal layer is not particularly limited, the thickness of the copper foil 2 is 10 to 20 μm, and the thickness of the nickel layer 3 is 5 to 10 μm in consideration of smoothness, adhesion, cost, and the like. ,
The thickness of the palladium nickel layer 4 is preferably 1.0 to 2.0 μm, and the thickness of the platinum layer 6 is preferably 0.3 to 1.0 μm.

It is to be noted that various enzyme layers can be provided on the platinum electrode according to the present invention without any particular limitation, whereby an enzyme electrode is obtained. The obtained enzyme electrode has higher measurement accuracy and reproducibility than before.

[0021]

The present invention will be described more specifically with reference to the following examples.

(Embodiment 1) As shown in FIG.
A copper foil 2 having a thickness of 18 μm is patterned on a glass epoxy substrate 1 having a thickness of m and a nickel layer 3 having a thickness of 7 ± 2 μm and a palladium nickel layer 4 having a thickness of 1.5 ± 0.2 μm are formed thereon by plating. Each of the films was formed, and then the gold particles 5 were uniformly fixed thereon by a gold strike treatment, and then a platinum layer 6 having a thickness of 0.5 ± 0.2 μm was formed thereon by a plating method to produce a platinum electrode. The center line average roughness indicating the surface roughness of this platinum electrode was 0.114 μm.

Then, an enzyme electrode was prepared by providing a polymer film containing glucose oxidase on the platinum electrode, and an aqueous solution having a glucose concentration of 100 mg / dL was measured. The result is shown in FIG. 3 as a box-whisker diagram, and it can be seen that the reproducibility is excellent. The result is shown in FIG. 4 as a normal probability plot, which shows normality.

(Comparative Example 1) As shown in FIG.
A copper foil 2 having a thickness of 18 μm is patterned on a glass epoxy substrate 1 having a thickness of 1.5 m, and a palladium nickel layer 4 having a thickness of 1.5 ± 0.2 μm and a platinum layer 6 having a thickness of 0.5 ± 0.2 μm are formed thereon. Platinum electrodes were formed by sequentially forming films. The center line average roughness of this platinum electrode was 0.208 μm.

Then, a polymer membrane containing glucose oxidase similar to that of Example 1 was provided on the platinum electrode to prepare an enzyme electrode, and an aqueous solution having a glucose concentration of 100 mg / dL was measured. The result is shown in FIG. 6 as a box-and-whisker diagram, and it can be seen that the reproducibility is inferior to the result of Example 1 (FIG. 3). Similarly, a normal probability plot is shown in FIG. 7, but it can be seen that the linearity is poor.

(Example 2) A metal layer was formed on a copper foil (center line average roughness 0.305 μm) after surface polishing as shown in the following conditions A to F to produce a laminate. The surfaces of the copper foil and each of the laminates were evaluated by center line surface roughness Ra, maximum height Ry, and 10-point average roughness Rz.

Condition A: Cu (18 μm) Condition B: Cu (18 μm) + Pt (0.5 μm) Condition C: Cu (18 μm) + PdNi (1.5 μm) + Pt (0.5 μm) Condition D: Cu (18 μm) + Ni (7 μm) + PdNi (1.5μm) + Pt (0.5
μm) Condition E: Cu (18 μm) + Ni (7 μm) + PdNi (1.5 μm) + Au strike + Pt (0.5 μm) Condition F: Cu (18 μm) + Au (4 μm) + Pt (0.5 μm)

FIG. 8 shows the center line surface roughness Ra, FIG. 9 shows the maximum height Ry, and FIG. 10 shows the ten-point average roughness Rz. It is clear that the surface of the body can be formed uniformly and smoothly, and it can be seen that the smoothness is further improved by interposing the gold strike layer.

[0029]

As described above, the platinum electrode for an enzyme electrode according to the present invention has a uniform and smooth surface, is inexpensive in spite of using a noble metal, and has an overall adhesion. It is possible to produce an enzyme electrode which is excellent in stability, stable over time, and excellent in analysis accuracy and reproducibility.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a platinum electrode for an enzyme electrode according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the platinum electrode for an enzyme electrode according to the present invention.

FIG. 3 is a box whisker diagram showing the measurement results of the glucose aqueous solution in Example 1.

FIG. 4 is a normal probability plot diagram in the first embodiment.

FIG. 5 is a cross-sectional view illustrating a platinum electrode manufactured in Comparative Example 1.

FIG. 6 is a box plot showing the measurement results of a glucose aqueous solution in Comparative Example 1.

FIG. 7 is a plot of normal probability in Comparative Example 1.

FIG. 8 is a graph showing a center line surface roughness Ra of the surface of each laminate produced in Example 2.

FIG. 9 shows the maximum height of the surface of each laminate produced in Example 2.
It is a graph which shows Ry.

FIG. 10 is a graph showing a 10-point average roughness Rz of the surface of each laminate produced in Example 2.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 copper foil 3 nickel layer 4 palladium nickel layer 5 gold or nickel particles 6 platinum layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Teru Sekiya 1-2-58 Hiromachi, Shinagawa-ku, Tokyo Sankyo Co., Ltd. (72) Masatoshi Yamamoto 2-7-12 Ginza, Chuo-ku, Tokyo Within Sankyo Co., Ltd.

Claims (4)

[Claims] 1. A platinum electrode for an enzyme electrode, comprising a copper foil, a nickel layer, a palladium nickel layer, and a platinum layer sequentially laminated on an insulating substrate. 2. The platinum electrode for an enzyme electrode according to claim 1, wherein a strike layer of gold particles or nickel particles is interposed between the palladium nickel layer and the platinum layer. 3. A method for forming an enzyme electrode, comprising: forming a copper foil on an insulating substrate, patterning a predetermined circuit, and sequentially laminating a nickel layer, a palladium nickel layer, and a platinum layer by plating. A method for manufacturing a platinum electrode. 4. A copper foil is formed on an insulating substrate, a predetermined circuit is patterned, a nickel layer and a palladium nickel layer are sequentially formed thereon by a plating method, and a gold particle or a palladium nickel layer is formed thereon by a strike process. A method for producing a platinum electrode for an enzyme electrode, comprising forming a platinum layer by plating after fixing a nickel particle layer.