JPH08247990A - Small-sized oxygen electrode and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a small-sized oxygen electrode in which the size is further reduced exceeding the conventional limit. CONSTITUTION: A small-sized oxygen electrode comprises a set of electrode patterns 22, 23 made of active parts 22A, 23A, external connection terminals 22C, 23C and leads 22B, 23B for connecting them provided on insulating boards 21, 31, where the parts 22A, 23A are connected to one another by electrolyte- containing member 24, which is covered with an oxygen permeable film 28, and the lead 22B of at least one pattern 22 is passed under the part 23A of at least the other pattern 23 via an insulating layer 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a small oxygen electrode which is inexpensive and suitable for mass production. Small oxygen electrodes are used for measuring oxygen concentration in various fields. For example, a biochemical oxygen demand (BOD) in water is measured from the viewpoint of water quality conservation, and a small oxygen electrode is used as a measuring instrument for this BOD. Further, in the fermentation industry, it is necessary to adjust the dissolved oxygen concentration in the fermentation tank in order to promote the fermentation efficiently, and a small oxygen electrode is used as the measuring instrument. Furthermore, the small oxygen electrode is used as a biosensor by immobilizing an enzyme and is also used for measuring the concentration of sugar, alcohol and the like. For example, glucose reacts with dissolved oxygen using the enzyme glucose oxidase as a catalyst and is oxidized to gluconolactone, which is used to reduce the dissolved oxygen that diffuses into the oxygen electrode cell. The glucose concentration can be measured from the consumed amount of.

As described above, the small oxygen electrode is used in various fields such as environmental measurement, fermentation industry and clinical medicine.
Particularly, in the medical field, in applications such as a glucose sensor for diabetic patients, it is very useful because of its small size and low price, which is disposable.

[0003]

2. Description of the Related Art As an oxygen electrode, there has been a Clark-type electrode made of glass or vinyl chloride for a long time, but it was not suitable for mass production because it could not be downsized. Therefore, the present inventors have developed a new type of small oxygen electrode utilizing the lithography technique and the anisotropic etching technique (Japanese Patent Laid-Open No. 63-238548: Japanese Patent Publication No. 6-1254). This small oxygen electrode has a recess formed by anisotropic etching on a silicon substrate, two electrodes are formed on the bottom of the recess through an insulating film, and then an electrolyte-containing body is housed inside the hole.
Finally, the upper surface of the hole is covered with a gas permeable film. The present inventors have also developed a technique of forming an electrolyte-containing body and a gas permeable film only on a required portion by screen printing (Japanese Patent Laid-Open No. 87767/1993). This small-sized oxygen electrode is small in size, has little variation in characteristics, and is inexpensive because it can be mass-produced in one batch.

FIGS. 1 (1) and 1 (2) are a plan view (1) and a sectional view taken along line AA of the conventional small-sized oxygen electrode.
This small oxygen electrode 1 is formed on a rectangular silicon substrate 11 having a SiO ₂ insulating film formed on the entire surface thereof, and the active portions 1 are formed on the rectangular silicon substrate 11.
2A, 13A, a pair of cathode patterns 12 and an anode pattern 1 composed of external connection terminal portions 12C, 13C and lead wire portions 12B, 13B connecting them.
3 are both formed as a silver film, and each active portion 12
A and 13A are connected to each other by an electrolyte containing body 14. The active portion 12A of the cathode pattern 12 acts as a substantial cathode, and the active portion 13A of the anode pattern 13 acts as a substantial anode.

In the overlapping region of the cathode 12A and the electrolyte-containing body 14, both are in contact with each other through an opening 15 provided in a hydrophobic film (not shown) such as a photoresist interposed therebetween, and the opening 15 Oxygen sensitive part (measurement part) 1
2S is defined. In the overlapping region of the anode 13A and the electrolyte containing body 14, both are in contact with each other through an opening 17 provided in a moisture impermeable film 16 such as polyimide interposed therebetween.

The electrolyte containing body 14 is covered with an oxygen permeable membrane 18 (FIG. 1 (2)). The oxygen permeable film 18 covers all the substrate regions (regions above the terminals 12C and 13C in FIG. 1A) other than the substrate region including the terminals (pads) 12C and 13C. The small oxygen electrode shown in FIG.
It is used by applying a constant negative voltage to the cathode with respect to the anode. When the sensitive part is immersed in the buffer solution in this state, the dissolved oxygen permeates the gas permeable membrane, reaches the working electrode (cathode), and is reduced there. The current value generated by this reduction reaction is measured, and the dissolved oxygen concentration can be known using this as an index.

Further, as the small-sized oxygen electrode of this type, the present inventors have also developed a combination of the anisotropic etching technique and the anodic bonding technique in order to make it more suitable for actual factory production and have higher performance. (Japanese Patent Laid-Open No. 4-1254
62). Since all of the above small oxygen electrodes are manufactured using lithography technology using silicon or glass substrates as the material, even if the best conditions such as equipment are set and there is a demand of tens of millions of chips annually, it is about the same as test paper. 1 of 10
It cannot be made as low as 0 yen or less. Therefore, in order to further reduce the cost, the present inventors have developed a small oxygen electrode in which a plastic substrate is used, an electrolytic solution is allowed to permeate the paper, and a gas permeable film is bonded to the sensitive part (Japanese Patent Laid-Open No. 6- 345
96).

[0008]

The conventional small-sized oxygen electrode described above is extremely small as compared with the conventional Clark-type oxygen electrode. However, in recent years, for example, in the medical field, there has been a demand for inserting oxygen electrodes into the blood vessels of patients and directly measuring various components in blood. For such applications, it is necessary to reduce the size of the small oxygen electrode to, for example, 1 mm or less in width, but the conventional small oxygen electrode shown in FIG. 1 has a width of 2 m.
The limit was about m.

The present invention goes beyond the limits of conventional miniaturization.
It is an object of the present invention to provide a small-sized small-sized oxygen electrode.

[0010]

In order to achieve the above object, the small-sized oxygen electrode of the present invention comprises an active part, an external connection terminal part, and a lead wire part connecting these parts on an insulating substrate. In a small oxygen electrode having a pair of electrode patterns each of which is connected to each other with an electrolyte-containing body, and the electrolyte-containing body is covered with an oxygen permeable membrane, at least one electrode pattern of The lead wire portion passes under the active portion of at least one other electrode pattern through the insulating layer.

[0011]

As shown in FIG. 1, the conventional small oxygen electrode is
Cathode and anode 12A, 13A, their lead wire portions 12B, 13B, and pads 12C, 13C
Were arranged in parallel on the same plane. In most cases this structure does not pose a problem. However, if further miniaturization is attempted, the space occupied by the lead wires cannot be ignored.
Unlike a semiconductor IC, in the case of a small oxygen electrode, the distance between the lead wire and another electrode pattern cannot be narrowed, for example, about 1 μm.

This is because the small oxygen electrode is used by introducing water into the inside thereof, so that the area of the cathode or anode which is in contact with the electrolytic solution and the lead wire portion must be sufficiently separated from each other, for example, gas. This is because the peeling of the permeable film causes the electrolytic solution to penetrate into the lead wire portion and cause a reaction. Therefore, in order to secure the reliability of the small-sized oxygen electrode, the patterns including the lead wires should be 100 to 200.
Must be separated by at least μm. Therefore, the conventional small-sized oxygen electrode cannot be downsized to a width of 1 mm or less.

In the miniature oxygen electrode of the present invention, the lead wire portion of at least one electrode pattern passes under the active portion of at least one other electrode pattern through the insulating layer. With this three-dimensional arrangement, more patterns can coexist in the same substrate area as compared with the conventional two-dimensional arrangement, and thus the width of the small oxygen electrode can be made smaller than before. . At that time, the insulation is ensured by the insulating layer interposed between the three-dimensionally stacked patterns, and even if the gas permeable film is peeled off, the electrolytic solution does not penetrate into the lead wire portion.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0015]

【Example】

[Embodiment 1] FIGS. 2 (1) and 2 (2) are a plan view (1) and a sectional view taken along line AA of the small oxygen electrode of the present invention. In the small oxygen electrode 2 of the present invention, the lead wire portion 22B of the cathode pattern 22 passes under the active portion (substantially anode) 23A of the anode pattern 23 via the insulating layer 29. By arranging the cathode lead wire portion 22B three-dimensionally with the anode 23A in this manner, the width of the small oxygen electrode can be reduced as compared with the planar arrangement in the conventional example of FIG.

The small oxygen electrode 2 of the present invention comprises a glass substrate 2
A pair of cathode patterns 22 and anode patterns 23, each of which is composed of active portions 22A and 23A, external connection terminal portions 22C and 23C, and lead wire portions 22B and 23B connecting these portions, are formed on the lower layer of the first layer. It is formed as a two-layer structure including a chromium film and an upper gold film. In each active portion 22A, 23A, a silver film is further formed on the gold film of the above two-layer structure, and the active portions 22A, 23A are connected to each other by the electrolyte containing body 24 which is in direct contact with this silver film. There is. The active portion 22A of the cathode pattern 22 constitutes a substantial cathode, and the active portion 23A of the anode pattern 23 constitutes a substantial anode.

In the region where the cathode 22A and the electrolyte containing body 24 are overlapped with each other, they are in contact with each other through an opening 25 provided in a hydrophobic film (not shown) such as a photoresist interposed therebetween, and the opening 25 is formed. Oxygen sensitive part (measurement part)
22S is defined. In the region where the anode 23A and the electrolyte containing body 24 are overlapped with each other, they are in contact with each other through an opening 27 provided in a moisture impermeable film 26 such as polyimide interposed therebetween. The moisture impermeable film 26 such as polyimide is formed on the lead wire portion 23B of the anode pattern 23.
Also covers.

The electrolyte containing body 24 is covered with an oxygen permeable film 28 (FIG. 2 (2)) finally formed on the entire surface of the substrate. The oxygen permeable film 28 is formed of the terminals (pads) 22C, 2
It covers all the substrate regions (regions above the terminals 22C and 23C in FIG. 2A) other than the substrate region including 3C. A procedure for producing the small oxygen electrode of the present invention in FIG. 2 will be described with reference to FIGS. In addition, in order to simplify the description, one small oxygen electrode chip will be described in this embodiment, but in reality, a large number of small oxygen electrodes are simultaneously formed on one substrate.

Step 1: Formation of electrode pattern and insulating film A cathode pattern 22, an anode pattern 23 and an insulating film 29 were formed by the following procedure.

1-1: Formation of Cathode Pattern 22 (FIG. 3) [1] A glass substrate 21 having a thickness of 500 μm was prepared and washed with a mixed solution of hydrogen peroxide and ammonia and concentrated nitric acid. [2] A chromium film 221 (thickness 400Å) and a gold film 222 (thickness 1500Å) were sequentially formed on one surface of the glass substrate 21 after the cleaning by vacuum deposition.

[3] A positive photoresist (OFPR-5000 manufactured by Tokyo Ohka Co., Ltd.) was spin-coated on the surface of the substrate, and the temperature was changed to 80 ° C.
After prebaking for 30 minutes, the photoresist was exposed and developed to form a photoresist pattern for etching.

[4] Gold film 222 and chromium film 221
Are sequentially etched with an etchant having the following composition, and the photoresist pattern is removed with acetone to remove the active portion (cathode) 22A and the lead wire portion 2
A cathode pattern 22 including 2B and a terminal portion (pad) 22C for external connection was formed. Gold etchant: 1g I ₂ + 4g KI + 4ml water Chromium etchant: 0.5g NaOH + 1g K ₃ Fe (CN) ₆ +
4 ml water

[5] The substrate was washed with heated mixed solution of hydrogen peroxide and ammonia and pure water, and then dried.

1-2: Formation of insulating film covering lead wire portion (Fig.
4) [6] On the substrate surface on which the cathode pattern 22 is formed in the above [4], a photosensitive polyimide stock solution (Toray, Photo Nice)
UR-3140) (spin coating condition: 2300 rp)
m, 30 seconds) and prebaked at 80 ° C. for 90 minutes. [7] Only the polyimide coating film on the lead wire portion 22B was irradiated with ultraviolet rays.

[8] The polyimide coating film was developed in a developing solution (Toray, DV-605), and then rinsed in isopropyl alcohol in three portions. [9] 150 ℃ for 30 minutes, 200 ℃ for 30 minutes, 300 ℃
The polyimide was cured by sequentially performing baking for 1 hour. As a result, the polyimide insulating film 29 covering the lead wire portion 22B of the cathode pattern 22 was formed.

1-3: Formation of anode pattern (FIG. 5) [10] Chromium film 231 is formed on the same substrate surface by vacuum deposition.
(Thickness 400Å) and gold film 232 (thickness 1000Å)
Were sequentially formed. [11] A positive photoresist (OFPR-5000 manufactured by Tokyo Ohka Co., Ltd.) was spin-coated on the same substrate surface, pre-baked at 80 ° C. for 30 minutes, and then exposed and developed to form a photoresist pattern for etching. Formed.

[12] Gold film 232 and chromium film 231
Are sequentially etched with an etching solution having the same composition as used in [4] above, and then the photoresist pattern is removed with acetone to remove the active portion (anode) 2.
3A, the lead wire portion 23B and the external connection terminal portion (pad) 23C were formed to form the anode pattern 23.

Step 2: Active portion (cathode and anode)
(Fig. 6) [13] Apply positive photoresist (OFPR-800 made by Tokyo Ohka Co., Ltd.) to the entire surface of the same substrate, pre-bake at 80 ° C for 30 minutes, and then expose to 30 ° C. It was immersed in toluene for 5 minutes, post-baked at 80 ° C. for 10 minutes, and then developed. As a result, a photoresist pattern was formed which covers only the active portions of the electrode pattern, that is, the cathode 22A and the anode 23A, and covers the other substrate regions.

[14] A silver film was formed on the entire surface of the same substrate by vacuum vapor deposition, and then the resist was removed with acetone, and then the silver film other than the active portions 22A and 23A was removed by lift-off. As a result, the outermost layer is the silver film 233 (see FIG.
(3)) Active part formed or cathode 22A
And the anode 23A (FIG. 6 (1)) was defined.

Step 3: Formation of water-impermeable film (FIG. 7) [15] A photosensitive polyimide stock solution (Toray, Photo Nice UR-3140) is applied to the entire surface of the same substrate (spin coating condition: 2300 rpm). , 30 seconds) and prebaked at 80 ° C. for 90 minutes. Similar to the above [7], ultraviolet rays were irradiated only to the lead wire portion 23B of the anode pattern 23 and the polyimide coating film of the active portion (anode) 23A other than the portion where the opening 27 was formed. Similarly to the above [8], the polyimide coating film was developed in a developing solution (Toray, DV-605), and then rinsed in isopropyl alcohol in three portions.

[16] 30 minutes at 150 ° C, 30 minutes at 200 ° C
After that, baking was performed sequentially at 300 ° C. for 1 hour to cure the polyimide. As a result, an electrolytic solution impermeable or water impermeable polyimide film 26 covering the lead wire 23B and most of the anode 23A other than the opening 27 was formed.

Step 4: Formation of Electrolyte-Containing Body (FIG. 8) [17] The electrolyte-containing body 2 is formed on the cathode 22A, the anode 23A, and the liquid junction portion 24X for electrically connecting the two.
4 was screen printed. The electrolyte-containing body 24 was prepared by dispersing powdered potassium chloride, trishydroxymethylaminomethane, and glycine in an alcohol solution of polyvinylpyrrolidone, and the solvent was evaporated after screen printing.

Step 5: Formation of oxygen permeable membrane (FIGS. 9 to 1)
1) Oxygen permeable film 28 is applied to a required portion by the following steps [18] to [20]
Was coated. [18] In the pad area (the substrate area including the pads 22C and 23C), a thermosetting release paint (XB-80 manufactured by Fujikura Kasei)
After screen printing 1) to a thickness of 100 μm,
At 20 ° C., it was heated and cured to form a peeling mask 30 (FIG. 9).

[19] Next, the silicone resin 28 (Tore Dow Corning Silicone SE9176) forming the gas permeable membrane was applied by spin coating and heated at 80 ° C. for 60 minutes in a humidified constant temperature bath. Cured.
Humidification was performed by setting a petri dish or beaker containing water in a thermostat (Fig. 10).

[20] The mask 30 formed in the pad area was peeled off with tweezers to remove the silicone resin 28 in that area, and the pad area (pads 22C and 23C) was exposed (FIG. 11). . This allows
The small oxygen electrode of the present invention in which the gas permeable membrane 28 was covered except the pad region was obtained. In this embodiment, pads 22C and 2C
The reason why 3Cs are arranged side by side in the board width direction is that lead wires for external connection can be more easily taken out than in the case of being arranged in the board longitudinal direction.

In this way, a large number of small oxygen electrodes 2 formed on the glass substrate 21 are individually cut off to obtain small oxygen electrode chips. In the small oxygen electrode of the present invention shown in FIG. 2, the thickness of the oxygen permeable film 28 on the oxygen sensitive portion 22S (FIG. 2 (1)) in the active portion 22A of the cathode pattern 22 is set to the other portion. It can be made thinner to improve responsiveness. Such a small oxygen electrode can be manufactured by the following procedure.

Steps 1 to 5 [19] are performed. Next, in the same manner as in the above step [18], the oxygen sensitive portion 22S in the active portion 22A of the cathode pattern 22 is formed.
The silicone resin film 28 (see FIG.
A second peeling mask 30A is formed on (1) and (2). Next, the second silicone resin film 28A is formed on the entire surface of the substrate including the exposed portion of the second peeling mask 30A and the silicone resin film (first silicone resin film) 28 in the same manner as the above procedure [19] ( (Fig. 13).

Finally, the peeling mask 30 in the pad area is peeled off by the same operation as in the above step [20], so that the silicone resin films 28 and 28A on the peeling mask 30 are peeled together and the pad area (22C, 23C) is exposed. Further, by peeling off the second peeling mask 30A, the second silicone resin film 28A is removed and the first silicone resin film 28 is left on the oxygen sensitive portion 22S. As a result, since the thickness of the silicone resin film is only the first silicone resin film 28 on the oxygen-sensitive portion 22S, the thickness of the silicone resin film at the other portions (the first silicone resin film 28 and the second silicone resin film) is (Total of membranes 28A) (FIG. 14).

In general, when potassium chloride or the like is used as the electrolyte, the anode is constructed as an electrode of silver and an insoluble halogen salt such as silver / silver chloride or silver / silver bromide. In order for the silver anode to react with the electrolyte to form such an electrode, it is necessary for the electrolyte to contain halogen ions. For that purpose, it is necessary to contain a halogen ion supply source in the electrolyte containing body. Further, it is desirable that the electrolyte containing body contains a buffering agent for fixing the pH of the electrolyte.

A large part of the anode 23A is covered with an electrolyte impermeable film 26 such as polyimide, and the anode 23A is formed by the film 2.
The electrolyte containing body 24 is contacted only within the range of the openings 27 of 6. The reason is as follows. That is, in order to prolong the life of the small oxygen electrode, it is advantageous that the anode area is large. However, when the anode area is large, the outermost surface of the anode gradually increases from the original Ag.
The stabilization time required to change to Cl becomes longer.
By covering most of the anode with an electrolyte impermeable membrane and contacting the electrolyte-containing body only in the openings, it is possible to achieve both long life and substantial stabilization in a short time.

Although the lead wire 22B of the cathode 22A is arranged below the anode 23A in the first embodiment, as shown in FIG. 15 (1), the small oxygen electrode 4 is used.
It may also be advantageous in some cases to arrange the lead 43B of the anode 43A below the cathode 42A in FIG. Further, in the first embodiment, the small-sized oxygen electrode having the cathode 22A and the anode 23A has been described.
The present invention can be appropriately applied to a small-sized oxygen electrode having a multi-pole structure of three electrodes or more, if necessary. For example, as shown in FIG. 15 (2) or (3), in the case of the small-sized oxygen electrode 51 having a three-electrode configuration of the working electrode 52A, the reference electrode 53A, and the counter electrode 54A, the counter electrode 54A occupying a relatively large area. It is advantageous to arrange the lead wire 52B of the working electrode 52A, or the lead wires 52B and 53B of the working electrode 52A and the reference electrode 53A underneath.

Although not shown in FIG. 15, the lead wires (43B, 52B, 53B) arranged below are covered with an insulating film, respectively, and are insulated from the electrode patterns above.

[Embodiment 2] As one of preferred embodiments of the present invention, as shown in FIG. 2C, the small oxygen electrode 3 has a cathode pattern 2 in a groove 32 provided in a substrate 31.
The second lead wire portion 22B and the insulating layer 29 on the second lead wire portion 22B are stacked and accommodated, whereby the groove 32 is filled and flattened, and the active portion 23A of the anode pattern 23 is provided thereon.

By forming another pattern on the flattened surface as described above, it is not necessary to make the step coverage a problem. A structure having the groove 32 shown in FIG. 2C was manufactured by the following procedure.

Step 01: Preparation of Substrate As a substrate used in this embodiment, a silicon substrate which is easy to form a groove in a semiconductor process is more suitable than the glass substrate used in Example 1.

[1] A (100) plane silicon substrate having a thickness of 400 μm is prepared and washed with a mixed solution of hydrogen peroxide and ammonia and concentrated nitric acid. [2] The washed silicon substrate is subjected to wet thermal oxidation at 1000 ° C. for 200 minutes to form a SiO ₂ insulating film having a thickness of 1.0 μm on both surfaces.

Step 02: Forming the SiO ₂ oxide film at the groove formation location
Removal [3] A negative photoresist (OMR-83, made by Tokyo Ohka Co., Ltd.) is applied to one surface of the silicon substrate on which the oxide film is formed, and the temperature is 80 ° C.
Bake for 30 minutes. The photoresist was then exposed, developed and rinsed. As a result, the photoresist in the portion where the cathode lead wire 22B is to be formed is removed.

[4] The same negative photoresist was coated on the entire surface of the substrate opposite to the above, and then baked at 150 ° C. for 30 minutes. [5] The substrate is made up of 1 part by volume of 50% hydrofluoric acid and 6 parts by volume of 40
By dipping in a mixed solution with% ammonium fluoride, the SiO ₂ oxide film on the exposed portion in the above [3] was removed. As a result, the surface of the silicon substrate where the cathode lead wire 22B was to be formed was exposed.

[6] The negative photoresist was peeled off by immersing the substrate in a mixed solution of 2 parts by volume of sulfuric acid and 1 part by volume of hydrogen peroxide.

Step 03: Groove formation [7] The substrate was placed in a 35% potassium hydroxide solution at 80 ° C. for 1 hour.
By immersing it for a period of time, the substrate silicon at the portion exposed in the above [5] was anisotropically etched. As a result, the groove 32 was formed at the place where the cathode lead wire 22B was to be formed. [8] The substrate was washed with a mixed solution of hydrogen peroxide and ammonia and concentrated nitric acid.

[9] The substrate was wet-oxidized at 1000 ° C. for 200 minutes to form a SiO ₂ insulating film having a thickness of 1.0 μm on both sides (similar to the reference numeral 31A shown in FIGS. 16B and 16B). Was formed. After forming the groove 32 in this manner, a small-sized oxygen electrode was produced by the same procedure as [2] and subsequent steps of Example 1.

[Embodiment 3] In another desirable mode of the present invention, in the structure shown in FIG.
It is possible to increase the amount of the electrolyte-containing body 24 retained on the anode 23A (via the electrolyte impermeable membrane) by providing a recess in the anode 23A at a position not passing below. Also in this case, the silicon substrate is used as in the second embodiment, and the groove is formed in the same manner as in the second embodiment.

As shown by hatching in FIG. 16 (1A), at a portion 33 where the cathode lead wire 22B does not pass therebelow, the anode is formed along the inner wall of the recess (or groove) 33 formed in the silicon substrate 31. Since 23A is formed, a depression (or groove) 34 corresponding to the anode 23A itself is formed (FIG. 16 (1B)). According to yet another preferred aspect, in the structure of FIG.
As shown in (A) and (2B), the lower portion of the liquid junction (the portion including only the electrolyte-containing body) 24X that connects the cathode 22A and the anode 23A with the electrolyte-containing body 24 is attached to the silicon substrate 3
It can also be received in the groove 35 provided in 1. Liquid junction 24
If the width of X is narrow or the composition of the electrolyte-containing body 24 is high and the liquid junction 24X is thin, the liquid junction 24
The conductance of X decreases, which may affect the stability of the small oxygen electrode. By providing the groove 35,
It is possible to secure the conductance at the liquid junction 24X.

Depressions (grooves) 33 and 35 in the silicon substrate 31
Can be formed by the same procedure as the groove 32 described in the second embodiment. The layer indicated by 31A in FIGS. 16 (1B) and (2B) is formed by wet oxidation after forming the groove 33 or 35 in the silicon substrate 31 and then in the same manner as in step 03, step [9] of the second embodiment. Is a SiO ₂ insulating film. The small oxygen electrodes produced in the above Examples 1 to 3 are immersed in water at room temperature overnight or more, or at a temperature of 120 in an autoclave.
By performing the treatment for 15 minutes at a temperature difference of 1.2 atm at a temperature of 50 ° C., water is supplied to the electrolyte in the form of water vapor, and the electrolyte can function as an oxygen electrode.

Example 4 A small biosensor shown in FIG. 17 was manufactured. This biosensor comprises a sensitive portion 22S (22) of a small oxygen electrode manufactured in any of Examples 1 to 3.
In (A), a glucose immobilizing film 61 on which an enzyme (glucose oxidase) is immobilized is provided. This is a sensitive part 22S (22A) of a small oxygen electrode in a solution prepared by dissolving 1 mg of glucose oxidase in 20 ml of a solution containing 5 wt% bovine serum albumin and 5 wt% glutaraldehyde.
Was dipped and then dried.

Example 5 An integrated biosensor shown in FIG. 18 was produced. This biosensor was produced by arranging two small oxygen electrodes in parallel on one chip in the same manner as in Examples 1 to 3, and the same procedure as in Example 4 was used to prepare the sensitive portion of one small oxygen electrode. Was prepared by providing a glucose oxidase-immobilized film 61 and a glutamate oxidase-immobilized film 62 on the sensitive part of the other small oxygen electrode.

As shown in FIG. 19, a small oxygen electrode is formed on both sides of a substrate by the same procedure as in Examples 1 to 3 to produce an integrated biosensor similar to the above. it can. Further, as shown in FIG. 20, the small-sized oxygen electrodes produced in Examples 1 to 3 can be adhered to each other on the back surfaces of the substrates to produce an integrated biosensor similar to the above.

Since the biosensor produced in Example 4 or 5 has the enzyme immobilized, it cannot be subjected to autoclave treatment for activation. Instead, the chip on which the enzyme is immobilized is immersed in normal temperature water for 12 hours or more to supply water to the electrolyte-containing body for activation. In the small oxygen electrodes and biosensors of Examples 1 to 5, only a part near the cathode serves as the sensitive part. Therefore, as shown in FIG. 21, it is desirable that the portion of the small oxygen electrode 70 other than the sensitive portion periphery 71 is housed in a tube 72 such as a silicone tube in order to suppress evaporation of water.

[0059]

As described above, in the miniature oxygen electrode of the present invention, the lead wire portion of at least one electrode pattern passes under the active portion of at least one other electrode pattern through the insulating layer. Due to the three-dimensional arrangement,
Since more patterns can coexist in the same substrate area as compared with the conventional planar arrangement, the width of the small oxygen electrode can be made smaller than the conventional one. At that time, the insulation is ensured by the insulating layer interposed between the three-dimensionally stacked patterns, and even if the gas permeable film is peeled off, the electrolytic solution does not penetrate into the lead wire portion.

[Brief description of drawings]

FIG. 1 is (1) a plan view and (2) a central cross-sectional view of a conventional small-sized oxygen electrode.

FIG. 2 is (1) a plan view, (2) a central cross-sectional view of a small oxygen electrode of the present invention, and (3) a central cross-sectional view of another embodiment.

FIG. 3 is a (1) plan view showing the first procedure for producing the small oxygen electrode of the present invention shown in FIGS. 2 (1) and (2),
(2) A central cross-sectional view and (3) a partially enlarged cross-sectional view.

FIG. 4 is (1) a plan view and (2) a central cross-sectional view showing the next procedure of FIG. 3.

FIG. 5 is a plan view (1) showing the next step of FIG. 4;
(2) A central cross-sectional view and (3) a partially enlarged cross-sectional view.

FIG. 6 is a plan view (1) showing the next step of FIG. 5;
(2) A central cross-sectional view and (3) a partially enlarged cross-sectional view.

FIG. 7 is (1) a plan view and (2) a central cross-sectional view showing the next step of FIG. 6.

8 is a (1) plan view and (2) a central cross-sectional view showing the next procedure of FIG. 7. FIG.

FIG. 9 is a (1) plan view showing the next procedure of FIG.
(2) A longitudinal sectional view around the sensitive part and (3) a lateral cross sectional view of a pad region.

10 is a plan view (1) showing the next step of FIG. 9, (2) a vertical sectional view around the sensitive part, (3) a horizontal sectional view of the central part, and (4) a horizontal sectional view of the pad region. is there.

11 is a (1) plan view, (2) center cross-sectional view, and (3) pad region cross-sectional view showing the next procedure of FIG.

FIG. 12 is a plan view (1) showing a state in which a second peeling mask is formed on the oxygen permeable film near the sensitive portion.
(2) A longitudinal sectional view around the sensitive part and (3) a lateral cross sectional view of a pad region.

FIG. 13 is a plan view (1) showing a state in which a second oxygen permeable film is formed on the entire surface after forming the second peeling mask, (2) a longitudinal sectional view around the sensitive part, and (3). It is a pad area cross-sectional view.

FIG. 14 is a plan view (1) showing the small oxygen electrode of the present invention in which the first and second peeling masks are peeled off to thinly form the oxygen permeable film in the sensitive portion; ) A longitudinal sectional view around the sensitive portion and (3) a lateral cross sectional view of a pad region.

FIG. 15 is a plan view showing (1) another two-pole configuration, (2) three-pole configuration and (3) another three-pole configuration of the small oxygen electrode of the present invention.

FIG. 16 is (1A) (2A) plan view and (1B) (2B) cross-sectional view showing an embodiment in which a groove (dent) for receiving an electrolyte-containing body is provided according to the present invention.

FIG. 17 is a cross-sectional view showing a small biosensor of the present invention.

FIG. 18 is a cross-sectional view showing the integrated biosensor of the present invention.

FIG. 19 is a cross-sectional view showing an integrated biosensor according to another embodiment of the present invention.

FIG. 20 is a cross-sectional view showing an integrated biosensor according to still another aspect of the present invention.

FIG. 21 is a perspective view showing a small oxygen electrode or biosensor of the present invention in which a portion other than the vicinity of the sensitive portion is housed in a tube.

[Description of Reference Signs] 1 ... Conventional small oxygen electrode 2 ... Small oxygen electrode of the present invention 21 ... Glass substrate 22 ... Cathode pattern 22A ... Active portion (cathode) 22C of cathode pattern 22 ... Lead wire portion 22C of cathode pattern 22 ... External connection terminal (pad) part of cathode pattern 22 Oxygen sensitive part (measurement part) 221 ... Chrome film (for cathode formation) 222 ... Gold film (for cathode formation) 23 ... Anode pattern 23A ... Active part of anode pattern 23 (Anode) 23B ... Lead wire portion of the anode pattern 23 23C ... External connection terminal (pad) portion of the anode pattern 23 231 ... Chromium film (for forming anode) 232 ... Gold film (for forming anode) 29 ... Insulating layer 24 ... Electrolyte Containing body 25 ... Opening 26 ... Moisture impermeable film such as polyimide 27 ... Mouth 28 ... oxygen permeable membrane 28A ... second oxygen permeable membrane 30 ... peeling mask 30A ... second release mask 31 ... silicon substrate 31A ... silicon oxide film (SiO ₂ film) 32, 33, 34, 35 … Grooves (or depressions)

Claims (27)

[Claims] 1. An insulating substrate is provided with a pair of electrode patterns each including an active portion, an external connection terminal portion, and a lead wire portion connecting these, and each active portion is mutually connected by an electrolyte containing body. In a small oxygen electrode in which the electrolyte-containing body is covered with an oxygen-permeable film, the lead wire portion of at least one electrode pattern is replaced with the active portion of at least one other electrode pattern through the insulating layer. Small oxygen electrode characterized by passing under. 2. A lead wire portion of the at least one electrode pattern and the insulating layer are stacked and accommodated in a groove provided in the substrate, whereby the groove is filled and flattened, and the flattening is performed thereon. The miniature oxygen electrode according to claim 1, further comprising an active portion of at least one other electrode pattern. 3. The set of electrode patterns comprises a pair of electrode patterns respectively corresponding to a cathode and an anode, and a lead wire portion of one electrode pattern is below an active portion of the other electrode pattern through an insulating layer. The small oxygen electrode according to claim 1 or 2, wherein the small oxygen electrode passes through. 4. The lead wire portion of the one electrode pattern and the insulating layer are stacked and housed in a groove provided in the substrate, thereby filling the groove and flattening it, and then adding the other layer to the groove. The small oxygen electrode according to claim 3, wherein at least one active portion of the electrode pattern is provided. 5. The small oxygen electrode according to claim 1, wherein the one set of electrode patterns comprises three electrode patterns corresponding to a working electrode, a reference electrode and a counter electrode, respectively. 6. The miniature oxygen electrode according to claim 1, wherein the insulating substrate is a silicon substrate or a glass substrate. 7. The miniature oxygen electrode according to claim 1, wherein the insulating layer is made of polyimide. 8. The miniature oxygen electrode according to claim 1, wherein a recess is provided in the active portion where the lead wire portion does not pass therethrough. 9. A lower part of a liquid junction consisting only of the electrolyte containing body connecting the active parts to each other is received in a groove provided in the substrate.
The small oxygen electrode according to any one of items 1 to 7. 10. The active portions forming the cathode and the anode are respectively covered with a silver layer,
The small oxygen electrode according to claim 3, wherein the electrolyte-containing body contains a halogen ion source. 11. The active parts constituting the working electrode and the reference electrode are each covered with a silver layer, and the surface of the silver covering the reference electrode is changed to silver chloride. 6. The miniature oxygen electrode according to claim 5, wherein at least the active portion of the electrode pattern corresponding to is covered with a gold layer, and the electrolyte containing body contains a halogen ion source. 12. The active portion that constitutes the anode comprises:
The electrolyte-impermeable film having good adhesion is covered, and the electrolyte-containing body is in contact with the film through one small opening formed in the film. Small oxygen electrode. 13. The small oxygen electrode according to claim 12, wherein the electrolyte impermeable film having good adhesion is made of polyimide. 14. A water-impermeable film having good adhesiveness is formed on all other surfaces of the substrate except for the openings of the active parts and the terminal parts of each electrode pattern. The small oxygen electrode according to any one of claims 1 to 5, wherein the electrolyte containing body and the oxygen permeable film are formed on the electrolyte containing body. 15. The small oxygen electrode according to claim 14, wherein the water-impermeable film having good adhesion is made of polyimide. 16. The electrolyte-containing body does not contain water, and the water necessary for the oxygen reduction reaction is supplied to the electrolyte-containing body through the oxygen-permeable membrane in the form of water vapor before use. The small oxygen electrode according to any one of claims 1 to 5. 17. The small oxygen electrode according to claim 16, wherein the electrolyte-containing body is formed by dispersing an electrolyte component and a buffer component in a powder form in a polyvinylpyrrolidone carrier. 18. The miniature oxygen electrode according to claim 1, wherein the oxygen permeable membrane is made of silicone rubber. 19. The oxygen sensitive portion in the active portion has a thickness of the oxygen permeable membrane smaller than that of other portions, and the oxygen permeable membrane is thin. The small oxygen electrode described. 20. The method for producing a small oxygen electrode according to claim 19, wherein the electrode pattern including the active portion, the insulating layer pattern, and the electrolyte-containing body pattern are formed on an insulating substrate. A step of forming a first peelable resin pattern that covers the terminal portion of the electrode pattern, a step of forming a first oxygen permeable film that covers the entire substrate surface from above each pattern, and the activity of the electrode pattern Forming a second releasable resin pattern on the first oxygen permeable membrane on the oxygen sensitive portion in the portion, including the second releasable resin pattern and the exposed portion of the first oxygen permeable membrane. A step of forming a second oxygen permeable film on the entire surface of the substrate, a step of exposing the terminal portion of the electrode pattern by peeling the first peelable resin pattern, and a second step By peeling off the releasable resin pattern, the second oxygen permeable film is removed on the oxygen sensitive part to leave the first oxygen permeable film, whereby the oxygen permeable film on the oxygen sensitive part is removed. And a step of making the thickness of the thin film thinner than that of other portions, the manufacturing method of a small oxygen electrode. 21. The small oxygen electrode according to claim 1, wherein terminal portions of the electrode pattern are arranged side by side in the substrate width direction at one end of the elongated substrate. 22. The small oxygen electrode according to claim 1, wherein a portion other than the sensitive portion is housed in a detachable container for preventing water evaporation. 23. A small biosensor, wherein an oxygen-sensitive part of the small oxygen electrode according to any one of claims 1 to 5 is immobilized with a biological substance such as an enzyme or a microorganism. 24. The integrated biosensor according to claim 23, wherein a plurality of oxygen sensitive parts carry different bio-related substances and are arranged on the same surface of the same substrate. 25. The integrated biosensor according to claim 23, wherein a plurality of oxygen-sensitive parts carry different bio-related substances and are arranged on both sides of the same substrate. 26. The small-sized biosensor according to claim 23, wherein a plurality of oxygen-sensitive parts are made to carry different bio-related substances, and two substrates arranged on one surface are bonded to each other on their back surfaces. 27. The part other than the sensitive part is housed in a removable water evaporation preventing container.
27. The miniature biosensor according to any one of claims 26 to 26.