JPH10232215A - Thin film electrode and its formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable manufacturing with stable quality in a simple, reliable, and speedy way by hot-stamping by a letterpress metal mold from transfer foil formed of a thin film conductive substance evaporated onto a base material. SOLUTION: First, a conductive substance is evaporated onto the surface of a synthetic resin (PET) film to form transfer foil 6. Platinum, gold, silver, or palladium, out of which a stable electrode is easy to form, is used for a conductive substance. A fiberglass-reinforced PET film 9 formed of a matrix such as sheet-shaped polyimide is used for an electricity-insulating substrate. A letterpress metal mold 13 is formed by pressing a negative film on which the shape of an electrode is formed against a metallic plate of brass, etc. Here, an electrode is formed by a hot stamping machine 50. In other words, the film 9 and the transfer foil 6 are placed opposedly to each other, delivered, and stopped temporarily. At this time, a heated upper board 1 is vertically lowered and the metal mold 13 presses the back surface of the transfer foil 6 with a predetermined pressure to complete the transfer of an electrode onto the surface of the film 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improved thin-film electrode and a method for forming the electrode.

[0002]

2. Description of the Related Art Recently, biosensors (electrochemical enzyme sensors) have been used as means for detecting specific components from living bodies such as blood.
There is a method. The biosensor includes an enzyme sensor, a microorganism sensor, an immunosensor, a tissue sensor, and the like based on a biomaterial constituting the biosensor, and the detection of a specific component by these uses a current detection method. For example, an enzyme sensor uses an enzyme that selectively acts on a specific component under a biocatalyst as a sensitive element, converts the physicochemical change that occurs at that time into an electric current through an electrode, and detects this as a voltage value. By doing so, the specific component contained in the original sample can be measured immediately.

[0003] The performance of biosensors must respond quickly to very small amounts of physicochemical changes and must be detected quickly, because the individual elements that make up the sensor are configured at the highest performance levels. This is achieved for the first time. One of the elements is an electrode. The performance of this electrode depends on the conductive properties of the material (conductive substance) that constitutes the electrode,
It depends on the means for forming the electrodes, the state of the formed electrodes (surface properties, adhesion to the substrate, etc.). Of course, when forming the electrodes, it is necessary to sufficiently consider whether or not the electrodes are formed faithfully with respect to the original design specifications, in terms of productivity, and the like. In this sense, various studies have been made, but this can be found in the following electrode forming means.

The following method is an example of an electrode forming means. That is, a method in which a masking plate obtained by forming an electrode-shaped pattern (image) by etching or the like in advance is brought into close contact with an insulating substrate, and a conductive substance is adhered to the substrate surface by vapor deposition means or the like through the plate. (Hereinafter referred to as method A).

As a second example, a method of forming an electrode-shaped pattern on a substrate by a photolithography method using a conductive substrate having a conductive substance provided on the surface of the substrate by means of vapor deposition or lamination or the like. (Hereinafter referred to as method B).

As a third example, a mask film in which a photoresist (positive type) is coated on the base and a pattern corresponding to an electrode is formed as a method incorporating the technical concept of the methods A and B. Is exposed and developed. Then, when the conductive material is evaporated from above by the vapor deposition means, only the portion corresponding to the electrode is vapor-deposited on the substrate, so that the photoresist that was finally masked is removed and removed. (Hereinafter referred to as method C.)

A fourth example is a screen printing method which is essentially different from the methods A to C. This is a conductive substance, for example, using a conductive paste prepared by kneading conductive carbon black in a photosensitive or heat-sensitive resist, through a screen plate on which a corresponding electrode pattern is formed, directly printing on the substrate, Finally, it is cured and adhered by exposure or heating. (Hereinafter referred to as method D.) The electrodes are generally composed of two electrodes, a working electrode and a counter electrode provided on an insulating substrate, but may be three electrodes further provided with a reference electrode.

[0008]

However, the above-described respective electrode forming methods also have the following problems, are not sufficiently satisfied, and require further study for improvement.

In the method A, since a close contact between the insulating substrate and the mask plate is not perfect, a minute gap is formed, and the vaporized conductive material enters the gap and is deposited. As a result of wraparound due to poor adhesion, unlike the original design specification,
The electrode is likely to be formed in a state where the electrode width is widened and lacks sharpness (the edges are not disturbed and the linearity is good). With such an electrode, there is a danger of a short circuit or a variation in resistance, so that an electrode that is sufficiently satisfactory as a biosensor cannot be formed after all. In addition, the adhesion between the insulating substrate and the conductive substance is not always sufficient, and the use durability is not sufficiently satisfied, or the formation is batchwise, and the mask plate must be closely adhered each time, and also in terms of productivity. Not satisfactory.

In the method B, when a conductive material is first etched, side etching is likely to occur, and as a result, an electrode finer than the original design specification is formed. When the electrode is finer, the adhesion is often weaker. In addition, on a conductive substrate using a noble metal such as gold or platinum, which is extremely excellent as a conductive material, ordinary nitric acid or an iron chloride solution cannot be used as a corrosive solution for etching. It is limited to zinc and the like. Copper and zinc are easily oxidized on the surface, and as a result, it is not possible to ensure the stability of resistance to long-term use. Another drawback is that the oxygen overvoltage is small compared to gold and platinum. Since the forming means itself requires a process of photoresist coating → exposure / development → etching → resist peeling and washing, electrodes cannot be formed very complicated and quickly.

Although the method C is effective in that it is not batchwise due to poor adhesion, which is a drawback of the method A, and that it is not batch-like, the method of the method A is not sufficient for the adhesion to the insulating substrate.
It is not different from the above, and since it is necessary to carry out the coating of the photoresist performed in the method B → exposure / development on the substrate in advance, the forming method itself is preferable, including the peeling off of the masked resist after the vapor deposition. is not.

In the method D, unlike the methods A to C,
This is effective in that the electrode layer can be formed thicker and directly and continuously on the insulating substrate. However, first, since the electrode forming conductive material is a conductive paste, the resistance of the conductive material itself is much higher than that of the conductive material formed by the vapor deposition means. That is, since the electrical sensitivity is poor, there is a limit in catching a small potential change. Therefore, in order to compensate for this drawback, measures such as increasing the amount of the specimen sample and increasing the area of the electrode formed on the base are taken. However, these countermeasures are disadvantageous in that a specific component can be measured more quickly with a smaller amount of an analyte sample, and in that a more compact biosensor is manufactured.

In general, carbon black containing a curable resin as a matrix is not sufficiently mixed and dispersible.
In addition, even if they are sufficiently mixed and dispersed, there is a disadvantage that the dispersion state changes with time. This leads to variation in resistance and its aging. That is, a uniform and stable resistance cannot be obtained.

Further, the surface of the electrode to be formed is non-uniform and tends to have an unnecessarily rough surface. An extremely fine and uniform rough surface acts in a preferable direction. However, if the rough surface is more than necessary and non-uniform, there is a disadvantage that components other than a specific component in the specimen sample are easily adsorbed on the electrode surface. When a printing means called screen printing and a high-viscosity conductive paste are used as ink, there is an unavoidable problem that the electrode surface is inevitably rougher than necessary and uneven.

The present invention solves the above-mentioned problems of the prior art, and in particular, has studied and found out a method of forming an electrode in order to efficiently manufacture a more improved biosensor. This is due to the following solution.

[0016]

A thin film electrode according to the present invention is provided with an adhesive layer on the surface of a transfer foil made of a thin film conductive material formed on a substrate by a thin film forming means, and on an insulating substrate surface. The thin film conductive material is one of gold, platinum, silver, and palladium, and the thickness of the transfer foil is 200 to 2,000 angstroms. .

In the method of forming a thin film electrode, an adhesive layer provided on the surface of a transfer foil made of a thin film conductive material formed by a thin film forming means on a base material coated with a release agent is provided with a surface facing the insulating substrate. Hot stamping with a heatable letterpress mold in which a predetermined electrode shape is made, thereby transferring and forming an electrode made of a thin-film conductive material on the surface of the insulating substrate. Is a metal letterpress.

Further, in the thin film electrode of the present invention, the electrode comprises at least a combination of a detecting portion and a lead portion, and is formed so as to wrap the entire outer periphery of the electrode with an enzyme fixing layer which specifically reacts to a specific substance. It is characterized by being used as.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thin film electrode formed in the present invention is used particularly for a biosensor, and there are mainly four types of biosensors using this electrode as described above. Of course, the present invention is not limited to this, but covers all biosensors using electrodes. In addition, as described above, the number of electrodes is often two, but the number of the electrodes is not limited because the biosensor may have three electrodes provided with a reference electrode.
The thin film electrode is not limited to a biosensor, and is not limited to being used as a sensor, an electrode, or the like of various devices.

The operation of the electrodes in the biosensor is as follows. For example, in the case of using a bipolar enzyme sensor, in order to measure glucose in blood as a specific component, the tip of a thin film electrode of a sensor composed of a combination of a working electrode and a counter electrode is entirely covered with a glucose oxidase carrier (acting as a biocatalyst). Is covered. When blood comes into contact with the glucose oxidase carrier, only glucose is selectively and quickly oxidized to produce hydrogen peroxide together with gluconic acid. This hydrogen peroxide diffuses in concentration and reaches the electrode surface. On the other hand, a constant bias voltage is applied to the counter electrode so that current flows smoothly to the working electrode. When hydrogen peroxide comes into contact with the electrode surface in such a potential state, oxidation occurs at the working electrode, and is reduced and water is generated at the counter electrode to generate a reaction current. Since the reaction current is proportional to the concentration of hydrogen peroxide, that is, the concentration of glucose, the reaction current is converted into an output voltage and measured via an electric signal detection device. Here, when a constant bias voltage is applied to the counter electrode, the electrode is made of the same material, and in the case of an electrode formed of two kinds of conductive substances having different ionization tendencies (for example, platinum and silver), There is no need to apply a bias voltage.

Next, the transfer foil will be described. The transfer foil is
Using a base material in which a release agent such as silicone is coated on a synthetic resin (PET) film (thickness is about 25 μm) or the like, a conductive material is formed on the surface at a predetermined thickness by a vapor deposition method. It is formed by uniformly vapor-depositing, and coating the surface of the vapor-deposited with an adhesive which firmly adheres to an electrically insulating substrate to be described later by heating and pressing. Here, as the conductive substance, a thin film forming means by a generally known physical method such as vacuum deposition, sputtering, or ion plating can be used, and the thin film has a small electric resistance (for example, a surface resistance value). Is 1 Ω / □ or less), and any material can be used as long as it allows current to flow quickly, and is not particularly specified.
For example, simple metals such as aluminum, zinc, copper, nickel, chromium, rubidium, palladium, platinum, and gold, and metal compounds such as indium tin oxide (ITO), tin dioxide, zinc oxide, and indium oxide can be exemplified. Above all, a conductive material made of any of platinum, gold, silver or palladium is preferable as a material which is easy to manufacture the transfer foil and can easily form a stable electrode without undergoing surface oxidation.

It is not preferable that the film thickness of the vapor deposition is too large or too small, and it is preferable that the film thickness is about 200 to 2000 angstroms, and preferably about 500 to 1000 angstroms. If the thickness is larger than necessary, the transfer cut becomes worse in hot stamping with a metal relief printing plate. As a result, the edges (straight lines) of the electrodes formed on the insulating substrate are reproduced in a distorted saw-like state. This is not preferable in terms of reproducing with stable performance. On the other hand, if the thickness is too small, an electrode having a predetermined resistance value is not formed, or the electrode may be peeled off from the base or may be disconnected.

The conductive material may be formed into a foil shape by rolling with a roll or the like. However, such an electrode is not preferable because the oxidation reaction on the electrode surface is not performed more quickly. This is probably because the electrode surface is too smooth, resulting in poor contact efficiency with the oxide. On the other hand, in the case of the foil by the vapor deposition method in the present invention, it is performed more quickly and reliably. This is because the surface of the foil formed by the method has an appropriate fine rough surface and is uniform over the whole, so that the area of the formed electrode surface is large, and the contact area with the oxide target is correspondingly large. It is thought to be. Here, too, it can be seen that the conductive transfer foil formed by the vapor deposition method particularly has a characteristic action that cannot be obtained by other methods.

The electrically insulative substrate on which the electrodes are formed must have the necessary characteristics (eg, chemical resistance, heat resistance, bending resistance, dimensional stability, etc.) for use as a biosensor. Any type (material, shape) can be used. For example, in general, sheet-like (about 0.1 to 1 mm thick) polyethylene terephthalate (PET), polyethylene naphthalate, polyether nitrile, polycarbonate, polyphenylene sulfide, polyimide,
It is a synthetic resin system such as a printed circuit board reinforced with glass fiber using a polyamideimide, phenol resin, or epoxy resin as a matrix. In addition, there may be mentioned a case where the insulating inorganic material is typified by various plate-like ceramics. Further, which of these is to be selected is preferably determined in consideration of ease of handling and processing.

The relief printing die can be obtained by means of plate making by using, for example, a commonly known photosensitive resin relief printing material for hot stamping or a metal plate such as an iron plate, a zinc plate or a brass plate. Can be. In the case of the resin relief plate material, a negative film having an electrode shape corresponding to the electrode (type, shape, size) to be formed on the insulating substrate is brought into close contact with the photosensitive surface, and exposed (ultraviolet light) It is obtained by a plate-making method called development-post-treatment (washing, drying, post-exposure). On the other hand, in the case of the metal plate, first, a thin photoresist is coated and dried, and the negative film is adhered to the photosensitive surface. Similarly, exposure (ultraviolet light) -development and post-processing (washing and curing of the resist) are performed. Peeling removal)
It is obtained by doing. Among these relief plates, a relief plate made of a metal plate is preferable. This is because the electrodes formed on the insulating substrate are reproduced more accurately, reliably and sharply.

The depth of a relief mold obtained by development or etching (referred to as a relief depth) is generally about 0.5 to 1.5 mm. If it is too shallow, there is a risk of transfer of unnecessary parts due to bottoming at the time of hot stamping.On the contrary, if it is too deep, there is a risk that letterpress relief will collapse during hot stamping, especially in the formation of fine electrodes. It is caused by

Next, hot stamping using a relief mold will be described. First, the hot stamping referred to here is to use a plain transfer foil and press down on an insulating substrate with a relief mold under heat and pressure for a certain period of time. Then, the vapor-deposited conductive material corresponding to the electrode shape of the relief is faithfully peeled off from the release layer of the transfer foil, transferred, and fixed. Therefore, this is different from hot stamping in which a transfer foil having an already formed shape is simply heated and pressed with a roll of silicon rubber or the like and transferred onto a substrate. This is because in the transfer method of the already formed shape, it is necessary to form the shape on a plain transfer foil in advance, but the formation process requires a complicated process, and the formation process and the hot stamping process are sufficient for handling. This is because care must be taken, and furthermore, the adhesion between the substrate and the transfer foil is not adhered with sufficient strength, and the risk of peeling is high.

Next, the actual hot stamping will be described with reference to the drawings. In general, continuous production is performed using a flat plate type continuous hot stamping machine (the main part is schematically shown in FIG. 1). The airplane 50 is further centered on a lower plate 3 (fixed) arranged horizontally facing and an upper plate 1 which moves up and down and embeds a heating means. Rolls 8 and 10 for feeding and winding the synthetic resin film 9 (roll shape) as the insulating substrate are provided before and after, and before and after the upper plate 1 are deposited transfer of the conductive material. Each of the rolls 5 and 7 for feeding and winding the foil 6 (roll-shaped) is attached to each of them. In the central portion of the upper plate 1 of the machine 50, a receiving table 4 for fixing the metal relief plate 13 and receiving the relief mold 13 is provided in the central portion of the lower plate 3.
The relief mold 13 is indirectly heated to a predetermined temperature by the heating means 2 embedded in the upper plate 1. The heating temperature here is determined mainly by the bonding temperature between the adhesive provided on the electrode-shaped conductive material surface separated from the transfer foil and the synthetic resin film. However, the temperature must not cause shrinkage or the like during use of the synthetic resin film and the transfer foil substrate. Such a temperature can be easily known by preliminary experiments.

When the hot stamping machine 50 thus prepared is subjected to hot stamping as follows, a desired electrode is immediately reproduced (formed) on the synthetic resin film 9 as an insulating substrate. Synthetic resin film 9 sent out from roll 8 while being in contact with cradle 4
At the same time, the transfer foil 6 is sent out from above so as to face the synthetic resin film 9 and temporarily stops. At this time, the adhesive surface of the transfer foil 6 on the surface of the vapor-deposited conductive material is in a state of facing the synthetic resin film 9, and the back surface of the opposite substrate 6 a is in contact with the relief surface of the relief mold 13. It is sent out in a state, and it is sent out with a small gap without facing. When both are temporarily stopped, the heated upper panel 1 descends vertically. Then, the relief mold 13 having an electrode shape provided at the center of the upper plate 1 pushes the back surface of the base material 6a with a predetermined pressure, and is transferred to the surface of the synthetic resin film 9 to finish. Since the time required to complete the transfer (pressurizing time) is generally a short time within several seconds,
It will be produced substantially continuously. Here, the relief mold 13 is effective as long as a large number of electrodes are formed on the plate, since a large number of electrodes can be formed at once. This will be described in more detail with reference to embodiments described later.

The hot stamping means is not limited to the flat plate type, but may be, for example, a rotary type, that is, a cylindrical relief plate in which a heating means is embedded, and a continuous transfer while rotating by means of a receiving roll. The means are not specified.

Under what conditions (the number of poles, the shape, the size, the arrangement, etc.) of the electrodes are determined by the type of biosensor or the like, the measuring means, etc., it cannot be uniquely determined. It is desirable to decide by preliminary experiments.

The thin-film electrode obtained according to the present invention is incorporated and used so as to function as the biosensor, and the method of functioning the thin-film electrode depends on a commonly used method. For example, when incorporated as an electrode of an enzyme sensor for measuring glucose as a biosensor, the operation is as follows. Glucose oxidase as a biocatalyst for promoting the oxidation-reduction reaction of glucose is immobilized by any method. The immobilization method generally includes a physical method of simply adhering to a substrate or the like having a permeation hole, a physicochemical method of adsorbing to a gel or the like, a chemical method of immobilizing by cross-linking, covalent bonding, or ionic bonding. Or a combination of the chemical method and the inclusive method, and the method is appropriately selected from these methods. The immobilized glucose oxidase is supported directly on the electrode surface or indirectly via a membrane that allows only glucose to pass through. The electrode supporting glucose oxidase is located at the tip of the biosensor, and is configured so that a sample containing glucose is injected into the electrode. At this time, a power supply circuit for applying a bias voltage is provided at the terminal of the counter electrode as necessary, while a circuit (signal signal) for measuring the amount of glucose by changing the current generated by oxidation or reduction to a voltage is provided at the working electrode. Detection device →
Output electric signals) are added to each other, and the whole is constituted.

[0033]

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

(Example 1) The transfer foil, the electrically insulating substrate and the metal relief used in the example were obtained as follows.

(1) Transfer foil After degreasing and cleaning, a 25 μm PET film subjected to corona discharge treatment was coated with silicone for release, and platinum was vapor-deposited thereon by 500 Å by vacuum vapor deposition.
In addition, the deposition surface is coated with an acrylic adhesive,
Rolled. The degreasing cleaning and corona discharge are for strengthening the adhesion to the release silicone, but this is not always necessary.

(2) Roll-shaped PET film of 100 μm which has been subjected to corona discharge treatment after cleaning the surface of the electrically insulating substrate.

(3) Metal relief plate Using a brass plate having a thickness of 3 mm, the corresponding electrode shape in the case of two poles was made by photolithography at a relief depth of 1 mm. This is shown in FIG. Electrode shapes of the working electrode 16 and the counter electrode 14 are laid out on the brass relief mold 13, and four sets of the electrode shapes are arranged horizontally at equal pitches. Here, the working electrode 16 is connected to a lead wire 17 having a width of 0.3 mm at a tip portion formed of a square having a width of 0.9 mm.
On the other hand, the counter electrode 14 is a U-shaped tip portion having a width of 1 mm,
It is connected to a lead wire 15 having a width of 0.3 mm. The gap between the U-shaped tip and the square tip is insulated with an interval of 1 mm.

Next, a flat plate type continuous hot stamping machine 50 shown in FIG. 1 was prepared. The machine 50 includes an upper plate 1 in which the heater 2 vertically moving as described above is embedded and a fixed lower plate 3 having a receiving base 4.
And a take-up roll 7 for winding up the base material 6a having the used transfer foil after the transfer are disposed together with the guide rolls 5a, 7a. On the other hand, on the lower platen 3 side, a feed-out roll 8 of the synthetic resin film 9 as the electrically insulating base and a take-up roller 10 for winding up the base 9a on which the electrodes are formed are arranged together with the guide rolls 8a and 10a. . The vertical speed of the upper platen 1, the temperature, the pressing force, the pressurization stop time (transfer time), and the speed of each roll are all adjusted and controlled by the automatic control means.

Hot stamping was performed under the following conditions. In the center of the upper plate 1, a brass relief mold 13 shown in FIG.
Was mechanically set in close contact, and the heater 2 was controlled so that the relief printing mold 13 was heated and adjusted to 140 ° C.
Then, the transfer foil 6 is loaded on the delivery roll 5, and the transfer foil 6 shown in FIG.
As described above, the paper was transferred from the guide roll 7a to the take-up roll 7 while being in contact with the surface of the relief mold 13 through the guide roll 5a. on the other hand,
The PET film 9 was loaded on a delivery roll 8, delivered as shown in FIG. 1, passed through a guide roll 8a, passed through a guide roll 10a while being in contact with the receiving table 4, and taken up by a roll 10. Then, the pressing force was set to 5 kg / cm ² and the transfer time was set to 0.3 second, stamping was started, and stopped when the transfer foil 6 was fed by 20 m.

The electrodes formed on the PET film 9 are:
The image was transcribed without any problem in appearance. Fifty samples were cut out of the image and the following test was performed to confirm the performance as an electrode of the biosensor. First, the size of the transferred electrode was enlarged and measured. The width of the U-shaped tip of the counter electrode is 0.94 to 0.97 mm, and the width of the lead wire is 0.26 to 0.29 mm, while the square tip of the working electrode is 0.86 to 0.89 mm. Corner, the lead wire width is 0.27 to 0.29 mm, and the gap between the U-shaped tip and the square tip is 1.04 to
1.1 mm. This indicates that the electrode shape of the relief mold 13 made of brass was reproduced approximately one-to-one.

Next, the peeling test using cellophane tape was repeated three times, but none of the peeling was performed. Thus, it was determined that the electrode had sufficient adhesive strength as an electrode of the biosensor.

The continuity test was checked using a resistance tester. When the tip of the tester was pressed against both ends of each electrode and the resistance value indicated on the meter was measured, it was in the range of 190 to 200Ω for all the electrodes, which had stable electric characteristics without variation. You can see that.

Further, five samples were taken out of the electrodes, and glucose was measured using the samples to confirm the performance of the enzyme sensor. The measurement was performed as follows. First, in each of the electrodes, the other portions were covered with an acrylic resin except for the tip portion (square shape) and the lead wire terminal portion. (Coating layer 23)

On the other hand, glucose oxidase is used as a biocatalyst, and is immobilized by one formulation called a crosslinking method as described below, and is fixed to the surface of the electrode tip with a thickness of about 20 μm. 25 were provided.
First, bovine plasma albumin was dissolved in a phosphate buffer adjusted to pH 7.0 so as to have a concentration of 15% by weight, and 5 ml of the dissolved solution was collected.
5 g was dissolved. (Hereinafter referred to as solution A.) Then, the entire tip portion of the electrode was immersed in solution A, dried for about 1.5 minutes, and then immersed in a 25% by weight glutaraldehyde aqueous solution. Dry for 5 minutes. This is a predetermined thickness 2
This was repeated until the thickness of the enzyme reached 0 μm. Finally PH
The entire tip of the electrode was washed with a phosphate buffer of 7.0 to complete the process.

FIGS. 3 and 4 show the entire configuration of the electrodes obtained by the above-described processes. FIG.
The configuration of the electrodes of the biosensor 51 is shown in a plan view.
That is, reference numeral 18 denotes a synthetic resin (PET) film, and the coating layer 23 comprises a working electrode 21 and a counter electrode 19 which are a detection electrode portion 24 of a pair of electrodes of the biosensor, and terminal portions of lead wires 20 and 22 of a lead portion. And insulating coating with an acrylic resin. And the working electrode 21
The reference electrode 19 is covered with an enzyme fixing layer 25 (glucose oxidase) so as to surround the entire outer periphery. FIG. 4 shows an AA cross section of the biosensor 51. The outer circumferences of the counter electrode 19 and the working electrode 21 are entirely covered with an enzyme fixing layer 25.

Next, using the biosensor 51 shown in FIG. 3 as a glucose measuring sensor, a power supply for applying a bias voltage was connected to the terminal of the counter electrode 19, and an operation amplifier was used for the terminal of the working electrode 21. Amplifying circuit and X-T for reading the voltage amplified and converted by the circuit
A measurement circuit was constructed in which recorders were connected in series.

Using the measuring circuit, the power supply is set to 0.
While applying a bias voltage of 4 V to the counter electrode 19, the next measurement sample was dropped on the detection electrode unit 24, and the voltage was measured by an XT recorder. The measurement sample is 100
PH7 containing a known concentration of glucose of mg / dl.
0 phosphate buffer. As a result, the voltage gradually increased, and after one minute, the voltage became constant. (Indicates complete termination of glucose redox.) At this time, XT
The voltage of the recorder was 98 for 5 electrode samples.
Was in the range of 101 mv. This indicates that all the electrodes obtained according to the present example have stable quality and performance.

[0048]

Since the present invention is configured as described above, it has the following effects. First, the electrode pattern as designed is faithfully reproduced on the electrically insulating substrate with a sufficient adhesive strength, so that a biosensor having always stable quality and performance can be manufactured.

[0049] Only specific components in a sample can be measured efficiently and quickly. This is considered to be caused by having a moderately uniform rough surface, unlike the screen printing method, for example.

The simple, reliable, and quick means for producing an electrode enables efficient production with stable quality at all times.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a main part of a flat-plate type continuous hot stamping machine.

FIG. 2 is a plan view of a relief mold made of brass in which the shape of an electrode is plate-made. .

FIG. 3 is an overall plan view of an electrode configured as a biosensor.

FIG. 4 is a sectional view of an electrode configured as a bi-sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper board 2 Heater 3 Lower board 4 Cradle 5 Delivery roll 5a Guide roll 6 Transfer foil 6a Base material 7 Take-up roll 7a Guide roll 8 Delivery roll 9 PET film 9a Electrode-formed PET film 10 Take-up roll 10a Guide roll 13 Brass letterpress mold 14 Counter electrode 15 Lead wire 16 Working electrode 17 Lead wire 18 PET film 19 Counter electrode 20 Lead wire 21 Working electrode 22 Lead wire 23 Coating layer 24 Detecting electrode part 25 Enzyme fixing layer 50 Hot stamping machine 51 Biosensor

Claims (6)

[Claims] An adhesive layer is provided on a surface of a transfer foil made of a thin film conductive material formed on a substrate by a thin film forming means,
A thin-film electrode formed by transfer formation on an insulating substrate surface. 2. A method for forming a thin film electrode, comprising the steps of: forming an adhesive layer provided on a surface of a transfer foil made of a thin film conductive material formed by a thin film forming means on a base material coated with a release agent; A thin-film electrode formed by transfer-forming an electrode made of a thin-film conductive material on the surface of an insulating substrate by hot-stapping with a heatable letterpress mold having a predetermined electrode shape. Forming method 3. The thin film electrode according to claim 1, wherein the thin film conductive material is one of gold, platinum, silver and palladium. 4. The transfer foil according to claim 1, wherein the transfer foil is a thin film conductive material having a thickness of 200 to 2,000 angstroms.
2. The thin-film electrode according to 1. 5. The method of claim 2, wherein the relief mold is a metal relief. 6. The biosensor according to claim 1, wherein the electrode comprises a combination of a detecting portion and a lead portion, and is formed so as to wrap the entire outer periphery of the electrode with an enzyme fixing layer which specifically reacts to a specific substance, and is used as a biosensor. The thin-film electrode according to claim 3.