JPS63311158A - Manufacturing method of compact oxygen electrode - Google Patents

Abstract

PURPOSE:To form a porous carrier including electrolyte selectively in holes, by coating a part other than the holes with resist, and thereafter filling the holes with photopolymerization monomer including the electrolyte, and hardening the solution. CONSTITUTION:An Si wafer 10 is anisotropically etched to form holes 16. An SiO2 layer 11 and an electrode 17 are formed in each hole. Then, the entire surface other than the parts of the holes 16 is coated with negative type resist 18. Then, said wafer 10 is immersed into photopolymerization monomer (e.g., acrylamide) solution and lifted. When the wafer is lifted, said solution is made to remain only in the holes 16. The solution is repelled with the resist 18 at the other part and the solution is not attached. Then, ultraviolet rays are projected, and the solution in the holes 16 is hardened. Porous polymer 19 including electrolyte is formed. The polymer 19 can be selectively formed in the holes 16. Therefore, mass production can be carried out.

Description

[Detailed Description of the Invention] [Summary] As a method for manufacturing a small and low-cost oxygen electrode, multiple holes made by anisotropic etching are filled with a photopolymerizable monomer solution containing an electrolyte, and then UV irradiation is performed. A manufacturing method in which gelation is achieved by adding an electrolyte to the product.

[Industrial application field]

The present invention relates to a method for manufacturing an oxygen electrode, and particularly to a method for manufacturing an oxygen electrode that achieves miniaturization and low cost.

Measurement of dissolved oxygen concentration is performed in a wide range of fields.

For example, from the perspective of water quality conservation, the amount of biochemical oxygen supply in water (Biological Oxygen Demand)
(abbreviated as BOD) is being measured, and an oxygen electrode is used as a measuring device for this dissolved oxygen concentration.

Furthermore, in the fermentation industry, in order to efficiently proceed with alcohol fermentation, it is necessary to adjust the dissolved oxygen concentration in the fermenter, and an oxygen electrode is used as a measuring device for this purpose.

Furthermore, the oxygen electrode is combined with an enzyme to form an enzyme electrode, and the concentration of sugars, vitamins, etc. is measured.

For example, glucose (CbH6012) is oxidized to gluconolactone (C6HI006) by reacting with dissolved oxygen using an enzyme called glucose oxidase (abbreviated as C0D) as a catalyst. Taking advantage of the decrease in oxygen, the concentration of glucose is measured from the amount of dissolved oxygen consumed.

Oxygen electrodes are used in various fields such as environmental measurement, fermentation industry, and clinical medicine.
When used by inserting it into the body, it is necessary to be small in size and low in price considering its disposable nature.

[Conventional technology]

As shown in FIG. 3, the conventional glass electrode is made of synthetic resin or glass, and a cathode ray 2 embedded in the synthetic resin or glass is fixed in the center of a cylindrical cell 1.
At this tip is a cathode 3 made of platinum (Pt).

Further, an anode 4 made of silver (Ag) is provided along the inner wall of the cell 1, and the cell 1 is filled with an electrolyte 5 usually made of a 1 mol potassium chloride (KC) aqueous solution. .

In addition, the opening of cell 1 is made of fluoroethylene propylene (abbreviated as FEP), which has a thickness of about 10 μm and is easily permeable to dissolved oxygen.
An oxygen permeable membrane 6 made of a fluorine-based resin such as ) is provided, and is fixed to the cell 1 with an O-ring 7 made of natural rubber or synthetic rubber.

Further, a cathode terminal 8 and an anode terminal 9 are provided at the terminal portion of the cell 1 and are connected to the cathode 3 and the anode 4 in a circuit.

Conventional glass electrodes are expensive because of this configuration, and even small ones are about the size of a pencil.

Therefore, it has been impossible to insert it into a human body by attaching it to a catheter.

Therefore, in order to solve this problem, the inventor developed silicon (
We have proposed and filed an application for a small oxygen electrode that uses a St) substrate to create a cell. (The application was filed on March 27, 1988.) Figure 2 is a cross-sectional view of the oxygen electrode that the inventor is currently applying for.
To outline the manufacturing method, a Si wafer 10 with the (100) plane as the substrate surface is thermally oxidized to form a silicon dioxide (5i(h) layer 11 on the surface, and then
Using photolithography, a plurality of cell formation positions are opened on the Si wafer 10, and anisotropic etching is performed to make holes in the Si wafer 10, resulting in cells 12 as shown in the figure. form.

Next, thermal oxidation is performed again to form the SiO□ layer 11 inside the cell 12.
After completing the entire process, electrodes 13 and 14 made of a vapor-deposited film of gold (Au) are provided on this inner surface.

Next, agarose (agar) is dissolved in a 0.1 mol MCII aqueous solution and filled into the cell 12. After the agarose is solidified, a silicone resin or a negative photoresist is applied thereon to form the gas permeable membrane 15. It is something to do.

In the oxygen electrode having such a configuration, both electrodes 13.
When a constant voltage (for example, 0.5 V) is applied between 14 and 14, the following reduction reaction of dissolved oxygen (0□) occurs on the surface of one of the electrodes, which becomes the cathode.

OK +2H20+4e-→40H--...(11
At this time, electrons transfer from the cathode to dissolved oxygen, causing a current to flow, and since this current value is proportional to the dissolved oxygen concentration, the current value is used as an index for quantitative determination.

[Problem that the invention seeks to solve]

As mentioned above, the inventor has proposed a small oxygen electrode by performing anisotropic etching on a St wafer to create a small cell and filling this cell with a gel-like electrolyte. The challenge is to find a way to fill the electrolyte in a way that is suitable for mass production and also to manufacture it at low cost.

[Means for solving problems]

The above problem can be solved by forming a plurality of holes using photo-etching technology and anisotropic etching technology, and then covering a silicon substrate with an electrode in each hole with a negative resist, except for the hole area. This substrate is immersed in a photopolymerizable monomer solution containing an electrolyte, and each hole is filled with the solution and cured by irradiation with ultraviolet rays to form a porous carrier containing the electrolyte in the hole. This problem can be solved by using a manufacturing method for small-sized oxygen electrodes.

[Effect]

Since the small oxygen electrode according to the present invention is mass-produced using photolithography technology and thin film formation technology that are used in the formation of semiconductor integrated circuits, the filling method of the electrolyte into the hole is difficult. It also needs to be done in a way that is suitable for mass production.

As a method of this invention, a porous polymer containing an electrolyte is formed in the holes all at once.
A porous polymer is created by dipping a substrate and filling the holes with ultraviolet rays, and acrylamide is used as the wood-philic monomer.

In this way, the electrolyte is preserved in the pores of the porous polymer.

In this way, a large number of holes can be filled with the electrolytic solution at once, but the problem in this case is that the porous polymer is also formed on the Si substrate surface other than the holes.

In order to prevent this, the present invention uses a negative type resist for photolithography.

That is, the negative resist is rubber-based and has hydrophobic properties, so that even if it is immersed in an aqueous solution, the portion covered with the resist will repel water.

Utilizing this, the present invention covers portions other than the holes with a negative resist and performs immersion treatment.

〔Example〕

FIG. 1 shows a method of implementing the present invention, and FIG.
), the Si wafer 10 on which the electrodes 17 have been formed in the holes 16 is coated by spin coating.
The entire front and back surfaces were coated with a negative resist (OMR-83, manufactured by Tokyo Ohka Co., Ltd.), and after prebaking, exposure and development were performed to cover the entire surface except for the holes 16 with a negative resist 18.

Next, the following four solutions were prepared for forming a porous polymer containing an electrolytic solution.

Solution A: N,N,N',N'-tetramethylethylenediamine (polymerization initiator) Add 0.1 mol of KCf aqueous solution to 0.46 mj2 and Loom ji! Something that is bound.

N, N'- to 10g of B liquid niacrylamide (base ingredient)
Add 2.5 g of methylene bisacrylamide (crosslinking agent), add 0.1 mol of KC1 aqueous solution to this, and make 100ml.
What was said.

Liquid C: Lipofuramine (vitamin BZI curing accelerator) 4m
0.1 mole of KCI in g! Add aqueous solution to 100 m p
What was said.

Solution D: 0.1 mol KCA aqueous solution.

The mixture was mixed at a ratio of A solution: B solution: C solution: D solution = 11:1:4.

The reason why it is not mixed from the beginning is that it tends to harden during storage before use, and storage stability is poor.

Next, when the Si wafer 10 shown in FIG. 5A is immersed in the mixed liquid and pulled up, the mixed liquid remains only in the holes 16 and does not exist in other positions.

When the entire surface of the wafer 10 on the side where the hole 16 is located is irradiated with ultraviolet rays, the mixed liquid is hardened as shown in FIG.
A porous polymer 19 having 0.1 mol of KC/aqueous electrolyte in its pores is obtained.

Note that the negative resist 18 formed on the surface of the Si wafer 10 may be left as is.

〔Effect of the invention〕

According to the present invention, it is possible to form a porous carrier that selectively retains the electrolyte only in the minute holes that form the oxygen electrode, thereby making mass production possible.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a method of carrying out the present invention, FIG. 2 is a sectional view of an oxygen electrode currently being applied for by the inventor, and FIG. 3 is a sectional view of a conventional oxygen electrode. In the figure, 5 is an electrolytic solution, 10 is a Si wafer, 13, 1
7 is an electrode, 16 is a hole, 18 is a negative resist, and 19 is a porous polymer.

Claims (2)

[Claims] (1) After forming a plurality of holes using photolithography and anisotropic etching, a silicon substrate with electrodes formed in each hole is coated with a negative resist except for the holes. The substrate is immersed in a photopolymerizable monomer solution containing an electrolyte, and each hole is filled with the solution and cured by irradiation with ultraviolet rays to form a porous carrier containing the electrolyte in the hole. A method for manufacturing a small oxygen electrode, characterized by: (2) The method for manufacturing a small oxygen electrode according to claim 1, characterized in that acrylamide is used as the photopolymerizable monomer.