JP3239803B2 - Biosensor manufacturing method and biosensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a biosensor and a biosensor, and more particularly, to a method for covering a base electrode formed on an insulating substrate.
Apply a solution containing at least a physiologically active substance, and then
The present invention relates to a method for manufacturing a biosensor by drying to form a coating film, and a biosensor manufactured by the method.

[0002]

2. Description of the Related Art Conventionally, a biosensor has been manufactured by applying a solution containing at least a physiologically active substance so as to cover a base electrode formed on an insulating substrate, and then drying it to form a coating film. A way to do that has been proposed. Specifically, for example, in the case of a biosensor employing glucose oxidase (hereinafter abbreviated as GOD) as a physiologically active substance, GOD and phosphate are covered so as to cover a base electrode formed on an insulating substrate. A method has been proposed in which a physiologically active substance solution containing the following is applied, and then a hydrophilic polymer substance solution containing sodium alginate and a phosphate is applied and dried to form a coating film. Here, the application amount of the physiologically active substance solution and the application amount of the hydrophilic polymer substance solution are controlled so as to be predetermined amounts based on the specifications of the biosensor.

[0003] If a biosensor is manufactured by such a method, it is considered that the film thickness of the coating film covering the base electrode becomes uniform and the signal level of the biosensor can be stabilized.

[0004]

However, the application amount of the physiologically active substance solution and the application amount of the hydrophilic polymer substance solution are controlled so as to be set in advance based on the specifications of the biosensor. However, since the preparation of the solution is performed manually, variations occur due to differences in procedures. In addition, since the prepared solution is prepared by dissolving a highly viscous substance, the dissolution state varies. Further, since the dissolved substance is altered by the pump pressure of the solution coating machine, the viscosity of the coating solution varies. Furthermore, the surface tension of the coating liquid varies.

[0005] Under the influence of these variations, the spread of the coating liquid on the base electrode varies, and the thickness of the coating film varies. When the film thickness of the coating film varies as described above, the signal level of the manufactured biosensor varies, and the measurement accuracy of the concentration of the substance to be measured decreases. Here, the variation of the signal level is
It occurs between production lots of biosensors, and in the worst case, the variation is about 40%. Specifically, it was found that when the film thickness was varied in the range of about 10 to 16 μm, the output signal (μA) of the biosensor varied as shown in FIG.

Further, among the above-mentioned solutions, the hydrophilic polymer substance solution has the greatest influence on the viscosity.
If a solution having a low viscosity is used instead of the hydrophilic polymer substance solution, it is considered that the variation in the film thickness can be reduced. However, for example, when measuring the concentration of a substance to be measured in blood, a certain thickness or more is necessary in order to prevent hydrogen peroxide from being decomposed by other components in blood. In addition, since a certain degree of viscosity is required, it is impossible to solve the above-mentioned disadvantages.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a method of manufacturing a biosensor capable of greatly reducing the variation in signal level between manufacturing lots. It is intended to provide a biosensor.

[0008]

According to a first aspect of the present invention, there is provided a method for manufacturing a biosensor, the method comprising: covering an electrode formed on a substrate;
Apply a solution containing at least a physiologically active substance, and then
In manufacturing a biosensor by drying to form a coating film, a solution containing at least a physiologically active substance is applied so as to cover the electrodes, and dried to form a coating film. This is a method of measuring and determining the applied amount of a solution containing at least a physiologically active substance, and manufacturing a biosensor based on the determined applied amount.

According to a second aspect of the present invention, there is provided a method for manufacturing a biosensor, which comprises forming a coating by applying a solution containing a physiologically active substance and then applying a solution containing no physiologically active substance. is there. A biosensor according to a third aspect is manufactured by the manufacturing method according to the first or second aspect.

[0010]

According to the method for manufacturing a biosensor of the first aspect,
A solution containing at least a physiologically active substance is applied so as to cover the electrodes formed on the substrate, and then dried to form a coating film. A solution containing a physiologically active substance is applied and dried to form a coating film, the thickness of the coating film is measured to determine the amount of the solution containing the physiologically active substance to be applied, and a biosensor is formed based on the determined application amount. Therefore, even if the above-mentioned various variations occur in the solution between the production lots, the variation in the film thickness of the coating film is greatly reduced, and the signal level of the biosensor between the production lots is reduced. Variation can be greatly reduced.

According to the method of manufacturing a biosensor of the second aspect, a coating film formed by applying a solution containing a physiologically active substance and then applying a solution containing no physiologically active substance is adopted as the coating film. Therefore, the same operation as the first aspect can be achieved. Since the biosensor according to claim 3 is manufactured by the manufacturing method according to claim 1 or 2, even if the above-described various variations occur in the solution between manufacturing lots, The variation in the film thickness of the biosensor can be greatly reduced, and the variation in the signal level of the biosensor between manufacturing lots can be significantly reduced.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Embodiments of the present invention will be described in detail. FIG. 1 is a longitudinal sectional view showing a state in the course of manufacturing a biosensor to which the present invention is applied. In FIG. 1, a work electrode 2 and a counter electrode 3 are formed on an insulating substrate 1 at a predetermined interval, and a resist layer 4 is formed so as to cover the counter electrode 3. Then, a solution 5 containing a physiologically active substance is applied so as to cover the work electrode 2.

Here, as the solution 5 containing a physiologically active substance, for example, when GOD is employed as the physiologically active substance, a solution containing GOD, phosphate and sodium alginate may be used. It may be a physiologically active substance solution containing sodium alginate and a phosphate and a hydrophilic polymer substance solution containing phosphate. In the former case, the solution is 1
It may be applied only once, but in the latter case, it is only necessary to apply a solution of a hydrophilic polymer substance after applying a physiologically active substance solution. Here, the phosphate is employed when the physiologically active substance is GOD. If the physiologically active substance is different, a phosphate corresponding to the type of the physiologically active substance is employed.
Further, instead of sodium alginate, a hydrophilic polymer substance such as polyvinyl alcohol, polyvinylpyrrolidone, and chitosan can be used. Of course, these hydrophilic macromolecular substances have a high viscosity like sodium alginate.

FIG. 2 is a longitudinal sectional view showing a state in which a solution is dried to form a coating film. In FIG. 2, a solution 5 containing a physiologically active substance is dried to form a coating film 6 covering the work electrode 2.
The structure is the same as that of FIG. 1 and 2 are diagrams showing only a part, and in actuality,
A solution 5 containing a physiologically active substance is applied to a large number of work electrodes 2 formed on the insulating substrate 1 and dried to form a coating film 6. After the coating film 6 is formed, the insulating substrate 1 is cut to obtain a large number of biosensors. Therefore, at least the biosensors obtained from the same insulating substrate 1 (biosensors for each production lot) have no or very small signal level variation.

FIG. 3 is a flowchart illustrating an embodiment of the method for manufacturing a biosensor according to the present invention. In addition,
The process of the flowchart in FIG. 3 is performed for each production lot. In step SP1, a solution containing a physiologically active substance is prepared. In step SP2, a solution for confirming the thickness of the coating film is applied, and the solution is dried to form a coating film. The film thickness of the coating film is measured using a cutting film thickness meter or the like, and in step SP4,
The application amount of the solution is determined based on the measurement result of the film thickness. In step SP5, in order to manufacture a biosensor as a product, the determined amount of the solution is applied and dried to form a coating film. A series of processing ends.

In drying the solution, it is preferable to carry out a drying treatment for about 10 minutes in an environment having a humidity of 10 to 20%, so as to prevent an increase in film thickness due to high humidity. it can. The application of the solution in step SP2 is performed, for example, by changing the application amount of the solution in a plurality of steps, and measuring the film thickness of the coating film corresponding to each application amount in step SP3. 13μ
It is preferable to determine the coating amount that will be m as the coating amount in step SP4. Here, the reason why the film thickness is set in this way is that the signal of the biosensor is in a stable region as can be seen from FIG. However, other methods (for example, a method of setting the application amount of the solution in two stages and performing an interpolation operation based on the corresponding film thickness) can be adopted.

Table 1 shows the results (μm) and the CV values (%) of the film thicknesses of the coating films corresponding to a plurality of coating amounts (μl) for the three production lots.

[0018]

[Table 1]

As is clear from Table 1, when the film thickness is, for example, 1
It can be seen that the coating amount of 2 to 13 μm differs for each production lot. Further, since the solution is applied to the space formed by the resist layer formed so as to cover the counter electrode 3, there is no inconvenience that the solution spreads more than necessary.
It can be seen that the film thickness increases almost in proportion to the increase in the coating amount. Table 1 shows that the height of the work electrode 2 and the counter electrode 3 is 18 μm, the height of the resist layer on the counter electrode 3 is 18 μm, the outer diameter of the work electrode 2 is 0.9 mm, and the space formed by the resist layer. Corresponds to the case where the diameter is set to 0.3 mm.

In the case of applying a physiologically active substance solution and a hydrophilic polymer substance solution in this order in forming the coating film 6, the amount of the physiologically active substance is not determined instead of determining the application amounts of both solutions. What is necessary is just to change the application amount of the hydrophilic polymer substance solution while keeping the application amount of the solution constant. This makes it possible to greatly reduce the variation in the film thickness while keeping the amount of the physiologically active substance from fluctuating.

[0021]

According to the first aspect of the present invention, even if various variations occur in the solution between the production lots, the variation in the film thickness of the coating film is greatly reduced, and the signal level of the biosensor between the production lots is reduced. This has a unique effect that the variation in can be greatly reduced. The invention of claim 2 has the same effect as that of claim 1.

According to the third aspect of the present invention, even if various variations occur in the solution between the production lots, the variation in the film thickness of the coating film is greatly reduced, and the variation in the signal level of the biosensor between the production lots is achieved. Can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view showing a state during the production of a biosensor to which the present invention is applied.

FIG. 2 is a longitudinal sectional view showing a state where a coating film is formed by drying a solution.

FIG. 3 is a flowchart illustrating one embodiment of a method for manufacturing a biosensor according to the present invention.

FIG. 4 is a diagram illustrating a relationship between a film thickness of a coating film and an output signal of a biosensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Work electrode 5 Solution containing physiologically active substance 6 Coating film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-168153 (JP, A) JP-A-63-168552 (JP, A) JP-A 8-327587 (JP, A) JP-A-2- 61548 (JP, A) JP-A-9-210948 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/327 G01N 27/414

Claims (3)

(57) [Claims] A solution (5) containing at least a physiologically active substance so as to cover an electrode (2) formed on a substrate (1).
And then drying to form a coating film (6). A method for producing a biosensor, comprising applying a solution (5) containing at least a physiologically active substance so as to cover the electrode (2). , Dried to form a coating film (6),
Measuring the thickness of the coating film (6) to determine the applied amount of the solution (5) containing at least the physiologically active substance, and manufacturing the biosensor based on the determined applied amount. Production method. 2. The method for producing a biosensor according to claim 1, wherein the coating film (6) is formed by applying a solution containing a physiologically active substance and then applying a solution containing no physiologically active substance. 3. A biosensor manufactured by the manufacturing method according to claim 1.