JP2564030B2 - Method for producing carbon thin film electrode for electrochemical measurement - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an electrode for electrochemical measurement used in a flow cell, a liquid chromatography, a biosensor, or the like.

[Prior Art] Electrochemical measurement is used for detecting hydrogen ion concentration in a solution, detection of trace metal ions, detection of trace components in a living body, and the like. It is important that the electrode material used for measurement be capable of measurement in a wide potential range. The measurable potential range, that is, the potential window differs depending on the electrode, the solvent, and the supporting electrolyte, and the electrode is ideally polarized within this potential window.

In the case of the most common aqueous solution system, if the type of electrolyte is the same, (1) hydrogen overvoltage (difference between actual hydrogen generation potential and theoretical equilibrium potential) is large (2) oxygen overvoltage (actual The potential window is wide for those having a large difference between the oxygen generation potential and the theoretical equilibrium potential) and (3) having a high electrode dissolution potential.

In fact, as electrode materials, precious metals such as gold, platinum and palladium, semiconductors such as mercury, SnO ₂ and In ₂ O ₃ , semimetals such as glassy carbon and crystalline carbon are used.
Among these materials, noble metals have a high oxygen overvoltage and are difficult to oxidize and dissolve, and thus can be used as a measuring electrode in a wide potential range on the oxidizing side. However, the gold electrode is likely to be complexed and dissolved in a solution containing halogen ions, cyan, etc., and the measurable potential range becomes small. Further, since noble metals have a small hydrogen overvoltage, they are difficult to use for measurement on the reduction side, and their use is limited.
On the other hand, a mercury electrode has a large hydrogen overvoltage and is suitable for measurement on the reduction side, but cannot be used for measurement of an oxidation reaction because dissolution occurs on the oxidation side. SnO ₂ and In ₂ O ₃ are used as transparent electrodes, and the measurable potential range is considerably wide, but on the reducing side, the electrodes are reduced to tin or indium.

The carbon electrode has strong corrosion resistance and has a wide potential window on both the oxidation side and the reduction side, so that it can detect substances in a wide potential range, and is most widely used as a sensor and a detector for a chromatogram.

On the other hand, in recent years, microelectrodes have been positively studied for the purpose of analyzing a minute amount of a solution sample, a minute region such as the inside of a living body, and application to a sensor or measurement of a substance in a living cell has been attempted.

Further, it is known that microelectrodes have high sensitivity and quick response, and are attracting attention as detection electrodes for flow injection and chromatography. The response behavior of the microelectrode depends on the electrode shape, and the response becomes faster as the electrode size decreases, so various electrode shapes and miniaturization of electrodes have been studied. In the carbon electrode, carbon fibers enclosed in the glass capillary or CV on the inner wall surface of the glass capillary.
An example in which a carbon film was deposited by the D method and the end face thereof was used as a minute ring electrode was reported in Anal. Chem., 58 (198
6), 1782.

Although these electrodes are advantageous for measuring minute areas such as in vivo, the detectable current value drops below the nA order,
Since noise increases and sensitivity decreases during measurement, there is a problem that it is difficult to measure a low-concentration sample and an electric shield is required during measurement.

To improve the sensitivity of the electrodes, increase the number of working electrodes, that is,
Arraying has been proposed.

In an attempt to make an array, an example of encapsulating a large number of carbon fibers in a plastic such as epoxy resin is used in Anal.Che.
m., 61 (1989), 159, a glassy carbon or crystalline carbon electrode is coated with an insulating film, and then a laser is used to form a large number of fine holes to form a large number of array electrodes. An example is Anal. Chem., 62 (1990), 1339.
However, it has a drawback that it takes a long time to manufacture an electrode. In particular, the former has a problem in the reproducibility of the response because the distance between the electrodes cannot be controlled accurately.

In recent years, application of lithography technology has been proposed as a method for producing a microarray electrode.

In this method, a resist is applied to a substrate, an image mask having an electrode pattern is overlaid, exposed and developed, and then a metal thin film is formed by a vapor deposition method or the like, and the resist is peeled off to form a microelectrode on the substrate. The resulting lift-off method or after a metal thin film is formed on an insulating substrate, a resist is applied, an image mask having an electrode pattern is overlaid, exposed, and developed, and the remaining resist is used as a mask. An etching method is known in which an electrode pattern is obtained by etching the exposed metal thin film.

In this method, a large number of microelectrodes having an arbitrary shape and a constant interelectrode distance can be produced on the substrate with good reproducibility.

In order to apply such a lithographic technique to a carbon electrode, a carbon thin film that is uniform, has process resistance, and is capable of pattern formation is required. In recent years, various carbon thin films have been obtained by a sputtering method or a CVD method, and it has been reported that microfabrication of these carbon thin films can produce a micron or submicron order pattern. However, a carbon film produced by the above vacuum process on a substrate such as glass or silicon is damaged or peeled off in water or an organic solvent, and it is impossible to repeatedly perform an electrochemical measurement. It was

In addition, because a sufficiently high-conductivity film cannot be obtained, if the wire is made into a band shape, a comb shape, or the like, and the wire is made finer to the micron order, the resistance increases remarkably, and it is There was a drawback that an electric potential could not be applied.

[Object of the Invention] An object of the present invention is to improve the above-mentioned current products, and is stable in water and in an organic solvent without film peeling or destruction, and is an electrochemical measurement capable of forming a fine pattern. Another object of the present invention is to provide a method of manufacturing a carbon thin-film electrode for use in a car.

[Structure of the Invention] The present invention will be summarized as follows.
Alternatively, a conductive carbon thin film formed by sandwiching a conductive film between an insulating substrate and the conductive carbon thin film formed entirely or in a pattern, and the conductive carbon thin film entirely or partially covered with a patterned insulating film In the electrode for electrochemical measurement consisting of, a conductive carbon thin film is prepared by a vapor deposition method of an organic compound, or a vapor deposition method, or a polymer thin film is applied on a substrate by a coating method, a spin coating method, an electrolytic polymerization method, Alternatively, it is formed by casting and then carbonized by heating, or a polymer thin film is formed on the substrate.
It is characterized in that it is formed by a coating method, a spin coating method, or a casting method, and then a conductive carbon film is formed by a carbon sputtering method or a CVD method.

The carbon thin film produced by the method of the present invention can be formed into a fine pattern, and is characterized in that it does not cause film peeling or destruction in water or an organic solvent, and enables stable electrochemical measurement.

That is, it has been difficult to form a fine array electrode with the conventionally known glassy carbon, crystalline carbon, carbon fiber, and carbon paste electrodes.

In addition, when a conventionally known carbon thin film is applied to an electrode, the film is broken in water or the like, which makes it difficult to use. On the other hand, in the electrode of the present invention, it is possible to obtain a carbon film in the form of a dense film having high crystallinity by vapor phase growth of an organic compound, and therefore it is excellent in uniformity and adhesion, or In addition, first, a film was formed in the form of a polymer thin film, then carbonized to carbonize, or a polymer was previously coated as an adhesive phase, and then a carbon film was formed by a sputtering method or the like. This has advantages such as high adhesion to the substrate and difficulty in peeling.

Furthermore, if a conductive film is provided between the insulating substrate and the carbon film itself is thin, the conductivity as an electrode does not decrease because of the conductive film even if the conductivity is low. The problem that the potential cannot be applied can be solved.

In addition, when a conductive polymer or an organic semiconductor is selected as the polymer to be carbonized, extremely large conductivity can be obtained as compared with a carbon film prepared by a conventional process, and therefore even if a fine pattern is prepared. The increase in resistance can be suppressed considerably.

Next, the pattern to be formed may be circular, annular, polygonal such as rectangular or hexagonal, linear, or a disk array in which these are arranged in an array or a comb. Further, in addition to the working electrodes having these various shapes, it is possible to integrally manufacture a reference electrode and a counter electrode which are necessary for electrochemical measurement.

Next, as a method of forming a pattern, a surface, or a substrate having an entire insulating property, or vapor deposition on the substrate, sputter deposition, CVD, liquid phase epitaxial growth, or the like on which a metal or semiconductor is formed, is vapor deposited, Form a conductive carbon thin film by CVD, carbonization of polymer film, etc.
After applying a resist to this, a method of exposing and developing the pattern to expose a part of the carbon film, or thereafter, by reactive ion etching or argon milling,
The method of transferring a pattern to a carbon film can be mentioned. Furthermore, after forming the carbon film, an insulating film such as silicon nitride or silicon oxide is formed by vapor deposition, sputter deposition, CVD, etc., and a resist pattern is formed on the insulating film, followed by reactive ion etching or argon. An electrode pattern can also be formed by etching a part of the insulating film by milling to expose the underlying carbon film.

A silicon substrate with an oxide film, a quartz plate, an alumina substrate, a glass substrate, or a substrate whose surface or the whole is insulative
A plastic substrate can be used. Examples of the conductive substrate include gold, platinum, silver, palladium, chromium, titanium, stainless steel, and those obtained by coating these on an insulating substrate.

Further, p and n type silicon, p and n type germanium, cadmium sulfide, titanium dioxide zinc oxide, gallium phosphide, gallium arsenide, indium phosphide, cadmium selenium, cadmium tellurium, molybdenum disulfide, tungsten selenide, copper dioxide, It is also possible to obtain by coating a substrate with a semiconductor such as tin oxide, indium oxide, or indium tin oxide.

In order to obtain a carbon thin film, a conductive film is interposed directly on the insulating substrate or between the insulating substrate and
In the production of an electrochemical measurement electrode composed of a conductive carbon thin film which is entirely covered or formed by patterning and a carbon thin film which is entirely or partially covered with a patterned insulating film, the carbon thin film is The organic compound used for the method for producing the carbon thin film electrode for electrochemical measurement in which the vapor growth method of the organic compound is produced by the vapor deposition method includes naphthalene tetracarboxylic acid anhydride, perylene tetracarboxylic acid anhydride, and A conductive carbon thin film that includes phthalocyanine and its derivatives, and is formed by coating a conductive film directly on an insulating substrate or by interposing a conductive film between the insulating substrate and covering the entire surface or in a pattern. , And a method for manufacturing an electrode for electrochemical measurement, which comprises a carbon thin film whose entire surface or a part is covered with a patterned insulating film. Polyphenylene vinylene is a polymer used in the production method in which the Bonn thin film is formed by coating the substrate with a spin coating method, electrolytic polymerization method, or casting method, and then carbonizing it by heating. , Polythienylene vinylene, polyfurylene vinylene, polyimide, polypyrrole, polythiophene,
Examples thereof include polyaniline, polyimide, phenol resin and its derivatives.

Examples of materials used for forming patterns on electrodes or used as insulating films include photosensitive polymers, silicon oxide silicon dioxide, silicon nitride, silicone resin polyimide and its derivatives, epoxy resins, and thermosetting polymers. it can.

EXAMPLES The present invention will be described in detail below with reference to the examples with reference to the drawings, but it goes without saying that the present invention is not limited to these examples.

Example 1 A silicon wafer with a 1 μm oxide film manufactured by Osaka Titanium Co., Ltd. was treated with a primer to improve the adhesiveness, and then,
Gagnon et al., “Polymer”, 28 (1987) No. 4, 56
The polyphenylene vinylene precursor synthesized by the method described in 8 was spin-coated and then dried. After repeating this precursor coating several times, it was heated and dried at 200 ° C. to form a polyphenylene vinylene precursor film in which some of the substituents were removed. The substrate is then placed in a decompressible quartz container at room temperature to 950 at 10 ^-3 Torr.
The temperature was raised to 0 ° C., held for 30 minutes, and then cooled. After cooling to room temperature, the pressure was returned to normal pressure to obtain a substrate on which a conductive carbon film having a metallic luster and a surface resistance of 3 kΩ was formed on an insulating silicon substrate.

This electrode was connected to Princeton Applied Research's potentiostat PAR273, and a part of the electrode was adjusted to 0.1 mol / L.
Immersion in a phosphoric acid loosening solution, sweeping the potential to -0.8 to 1.2 V, and comparing the resulting voltammograms with those of gold or platinum electrodes, the carbon electrode showed almost no residual current and a wide potential. Whereas a window was obtained, a reduction current of hydrogen was observed on the reduction side with platinum and gold electrodes, and the carbon electrode obtained from polyphenylene vinylene exhibits the same excellent behavior as ordinary glassy carbon electrodes. Was confirmed.

Example 2 Similar to Example 1, a 1 μm oxide film-attached silicon substrate 1 manufactured by Osaka Titanium Co., Ltd., whose cross section is shown in FIG. 1A.
After coating the polyphenylene vinylene precursor on the surface several times, it was heated and dried at 200 ° C.
The precursor film 2 shown in 1 was formed. Then 10 ^-3 Torr
Under reduced pressure, the substrate was heated at 950 ° C. for 30 minutes and then cooled to obtain a substrate having a conductive carbon film 3 shown in FIG. 1C having a metallic luster and a surface resistance of 3 kΩ.

This substrate is coated with V3 positive resist thin film 4 manufactured by Tokyo Ohka Co., Ltd. shown in FIG. 1D, and after prebaking at 90 ° C. for 90 seconds,
Canon mask aligner PL using chrome mask
Contact exposure was performed with A501 for 30 seconds. In the resist developer NMD-W manufactured by Tokyo Ohka Co., Ltd., development is carried out at 20 ° C. for 40 seconds, followed by washing with water and drying to have the patterned resist film 5 of FIG. 1E in which the conductive carbon film surface is exposed. A microdisk array electrode was obtained. An enlarged perspective schematic view of the produced electrode is shown as FIG.

The diameter of the micropore electrode 6 was 2 μm, and the number thereof was 2500.

This electrode was used as a silver / silver chloride electrode and a platinum wire as a reference electrode and a counter electrode, respectively, and immersed in a phosphate buffer solution containing 100 μmol / L ferrocenylmethyltrimethylammonium bromide, so-called water-soluble ferrocene, When the potential was swept within the range of 0 to 0.7 V, a limiting current of 0.060 μA, which was independent of the potential sweep speed, was obtained. This value was obtained by multiplying the theoretical current value of the microdisk electrode: i = 4nrDFC (n: valence, r: electrode radius, D: diffusion coefficient, F: Faraday constant, C: concentration of active species) by the number of electrodes: 2500. The value was in good agreement with 0.059 μA.

Example 3 The same operation as in Example 2 was performed on a substrate having the same thickness as that of the silicon substrate with an oxide film used in Example 2 and having a thickness of 1000 Å deposited on the substrate. A substrate having a high surface resistance of 6Ω was obtained. This electrode was finely processed in the same manner as in Example 2 to obtain an array electrode having an electrode diameter of 1 μm and a number of 10,000.

This electrode is immersed in a phosphate buffer solution containing 100 μmol / L of water-soluble ferrocene by using a silver / silver chloride electrode and a platinum wire as a reference electrode and a counter electrode, respectively, and the range of 0 to 0.7 V is adjusted to 10 V.
When the potential was swept at a speed of 0 mV / sec, a limiting current of 0.12 μA, which was independent of the potential sweep speed, was obtained.

This value was almost the same as the theoretical current value of the microdisk electrode multiplied by the number of disks.

Also, when the potential sweep speed is 10 V / sec and measurement is performed,
Oxidation and reduction peaks based on diffusion rate control are obtained, and the peak separation of oxidation current and reduction current is less than 60 mV. The iR drop due to the shortage could be suppressed.

In addition, when the potential of this disk array electrode was swept to −0.8 to 1.2 V in a 0.1 mol / L phosphate buffer solution containing no active species according to the method of Example 2, the obtained portangram was obtained in Example 2. Consistent with what was obtained, it was confirmed that the carbon film formed on the gold thin film was pinhole-free.

Example 4 The substrate on which the conductive carbon film was formed in Example 3 was used as a plasma CVD apparatus AMP-3300 manufactured by Applied Materials.
Put in, nitrogen, silane, ammonia, respectively,
Flow rate 78, 23, 48SCCM, substrate temperature 300 ℃, pressure 0.2Torr,
An insulating film of silicon nitride having a thickness of 0.3 μm was formed on the conductive film under the condition of power of 500 W.

After that, a microdisk pattern was formed by the same resist work as in Example 2, and a gas mixture of CF ₄ / O ₂ = 9/1 was used as an etchant by a reactive ion etching device DEM-451 manufactured by Anerva, and a pressure of 2 Pa was used. Under the conditions of a gas flow rate of 25 SCCM and a power of 70 W, a microdisk electrode in which the silicon nitride insulating layer was disk-shaped was obtained.

 The disk diameter was 0.5 μm and the number was 40,000.

This electrode is used as a reference electrode and a counter electrode using a silver / silver chloride electrode and a platinum wire, respectively, and immersed in a phosphate buffer solution containing 100 nmol / L of water-soluble ferrocene.
When the potential was swept at a speed of 0 mV / sec, a limiting current of 0.24 nA, which did not depend on the potential sweep speed, was obtained.

This value was almost the same as the theoretical current value of the microdisk electrode multiplied by the number of disks.

Example 5 A silicon substrate with a 1 μm oxide film manufactured by Osaka Titanium Co., Ltd. and 3,4,9,10-perylenetetracarboxylic acid anhydride were placed in a quartz tube capable of being depressurized, and, for example, , Apply.Phys.Lett., 36 (1980), 86
According to the method of Kaplan et al. Described in 7, the thermal decomposition of 3,4,9,10-perylenetetracarboxylic acid anhydride was carried out under the condition of 1000 ° C. and 10 ⁻³ Torr, and the thermal decomposition product was deposited and deposited on the silicon substrate. .

After holding at 1000 ° C. for 15 minutes and then cooling, the substrate was taken out at room temperature and atmospheric pressure to obtain a substrate having a polyperinaphthalene conductive carbon film having a surface resistance of about 100Ω. Example 2
A conductive carbon film microdisk electrode was produced by a resist work in the same manner as in.

 The electrodes had a diameter of 2 μm and the number was 2500.

This electrode is used as a silver / silver chloride electrode and a platinum wire as a reference electrode and a counter electrode, respectively, and is immersed in a phosphate buffer solution containing 100 μmol / L of water-soluble ferrocene, and the potential is swept in the range of 0 to 0.7 V. Then, the magnitude which does not depend on the potential sweep speed is 0.06.
A limiting current of 0 μA was obtained, and this value was in good agreement with the theoretical current value of the microdisk electrode multiplied by the number of electrodes.

In addition, gold and platinum array electrodes were prepared by the same method, and the voltamgram obtained by sweeping the potential to -1.0 to 1.2 V in a 0.1 mol / L phosphate buffer solution containing no active species was compared. In the carbon microdisk electrode, almost no residual current was observed, and a wide potential window was obtained, whereas in the platinum or gold electrode, a reduction current of hydrogen or the like was obtained on the reduction side.

This electrode is placed in a phosphate buffer solution, for example Anal.C.
hem., 53 (1981), 1386, followed by activation for 12 seconds at a potential range of 0 to 3 V and a frequency of 70 Hz by the method of Gonon et al., then containing dopamine: 1 μmol / L, L-ascorbic acid: 10 μmol / L Dpamine and L
-A peak based on the oxidation of ascorbic acid was obtained with approximately 190 mV separation.

This is almost in agreement with the value measured using a carbon fiber or a glassy carbon electrode, and it was confirmed that the thin film obtained by vapor phase synthesis behaves electrochemically like a carbon electrode.

Example 6 A conductive carbon coating film having a surface resistance of several Ω was obtained by performing the same operation as in Example 5 on a platinum film having a thickness of 1000 liters deposited on a silicon substrate with an oxide film.

Similarly to Example 4, a silicon nitride insulating film was formed and patterned to obtain a microdisk electrode having a silicon nitride insulating sweep.

 The disk diameter was 0.5 μm and the number was 40,000.

This electrode was used as a silver / silver chloride electrode and a platinum wire as a reference electrode and a counter electrode, respectively, and 100 μmol / L ferrocene and 0.
When it is immersed in an acetonitrile solution containing 1 mol / L of supporting electrolyte tetraethylammonium tetrafluoroborate and the potential is swept at a rate of 100 mV / sec in the range of 0 to 0.7 V, the magnitude of 0.97 μA independent of the potential sweep rate is obtained. The limiting current was obtained. This value was almost the same as the theoretical current value of the microdisk electrode multiplied by the number of disks. Also, after plating the disc electrode with mercury,
Cadmium ion 10 ppb Lead ion 5 ppb in a sodium chloride aqueous solution containing a silver / silver chloride electrode and platinum wire, and while stirring the solution, to the silver / silver chloride electrode, −0.
A potential of 9V was applied for 60 seconds. After that, change the potential from -0.8 to-
By stripping the potential by differential pulse method at a rate of 50 mV / sec up to 0.1 V, a stripping voltammgram due to the oxidation of cadmium and lead could be obtained.

Example 7 A polyimide film was applied on a silicon substrate with an oxide film to a thickness of 1 μm, and heated in an electric furnace at 200 ° C. for 30 minutes to be thermally cured. This substrate was attached at a predetermined position in the Anerva sputter system SPF-332H, and a carbon film
It was formed on a polyimide under the conditions of W, 0.4 Pa for 20 minutes.

This electrode was microfabricated by the same method as in Example 2 to obtain an array electrode having an electrode diameter of 1 μm and a number of 10,000. This electrode is immersed in 100 μmol / L of a water-soluble ferrocene-containing phosphate buffer solution using a silver / silver chloride electrode and a platinum wire as a reference electrode and a counter electrode, and 100 mV / V in the range of 0 to 0.7 V. se
When the potential was swept at the speed of c, a limiting current of 0.12 μA, which did not depend on the potential sweep speed, was obtained.

This value was almost the same as the theoretical current value of the microdisk electrode multiplied by the number of disks.

Example 8 The same operation as in Example 5 was performed on the silicon substrate A with an oxide film shown in FIG. 3 at a thermal decomposition temperature of 1100 ° C.,
A conductive carbon film 3 having a surface resistance of 20Ω shown in FIG. 3B was obtained.

This electrode is coated with a photoresist V3 made by Tokyo Ohka Co., Ltd. as shown in FIG. 3C and heat-cured at 90.degree. C. for 90 seconds. Then, using a mask mask liner PLF-521 made by Canon, using a chrome mask. It was contact exposed and developed for 25 seconds. After that, this substrate was placed in a reactive ion etching device DEM-451 manufactured by Anelva, and the flow rate of oxygen gas was 100 SCC.
The carbon film was patterned by etching for 10 minutes under the conditions of M1Pa and 70W to obtain a lower electrode shown in FIG. 3D.

Next, after removing the resist with a solvent from this substrate, a plasma CVD apparatus AMP-3300 manufactured by Applied Materials, Inc.
The thickness shown in FIG. 3E under the same conditions as in Example 4.
An insulating film 7 of silicon nitride having a thickness of 0.3 μm was formed.

Further, the substrate is again coated with a resist, a mask is used, and as shown in FIG. 3F, a comb pattern is exposed and developed, and then the sputtering apparatus SPF-3 manufactured by Anerva is used.
Mounted at a predetermined position in 32H, as shown in Fig. 4G, the chrome film was sequentially powered at 100W, 0.4Pa for 10 seconds, and the platinum film was sequentially powered at 600W, 0.4Pa for 60 seconds. Formed.

After that, this substrate was immersed in methyl ethyl ketone and subjected to ultrasonic cleaning to remove the resist other than the electrode forming portion to form an upper comb-shaped working electrode as shown in FIG. 4H.

Then, this substrate was put into the plasma CVD apparatus again to form a silicon nitride insulating film having a thickness of 0.3 μm as shown in FIG.

Finally, the resist is coated again on the substrate and patterned by a chrome mask to expose the comb-shaped electrode and the pad portion as shown in FIG. 4J, and then a reactive ion etching apparatus is used. CF ₄ gas flow rate 25SCC
The silicon nitride film was etched as shown in FIG. 4H until the upper platinum electrode and the lower carbon electrode were exposed under the conditions of M, 2 Pa and power of 70 W.

As a result, as shown in FIG. 4K, the upper electrode and the lower electrode were separated by the insulating step, and the interdigitated comb-shaped electrode was obtained.

The width of each of the upper and lower electrodes was 5 μm, the gap was 0.3 μ, and the number of combs was 100.

This electrode is ruthenium hexamine 100 μmol / L, and immersed in an acetonitrile solution containing a supporting electrolyte tetraethylammonium tetrafluoroborate 0.1 mol / L, the platinum upper electrode is fixed at 0 V, and the carbon lower electrode is When the potential was swept at a rate of 100 mV / sec in the range of 0 to -0.7 V, the limiting currents due to the oxidation and reduction of ruthenium hexamine were observed at both the platinum electrode and the carbon electrode. In addition, the same measurement was carried out with the concentration of ruthenium hexamine set to 1 μmol / L. Compared with a platinum comb electrode on both sides, the platinum electrode could not obtain a good oxidation current due to the reduction current of hydrogen, etc. hand,
In this comb-shaped electrode, since the oxidation side electrode of the lower electrode is made of carbon, the residual current, that is, the faradaic current other than the reduction current of ruthenium hexamine is small and the S / N ratio is high.
The current on the oxidation side could be measured by the ratio.

[Effects of the Invention] As described above, according to the method for producing a carbon thin film electrode for electrochemical measurement of the present invention, 1) is it produced by coating a polymer and then carbonizing or vapor-phase polymerization reaction of an organic compound? , Or high adhesion to the substrate for use as a polymer adhesion layer, does not cause film breakage or peeling even when a potential is applied in water or an organic solvent,
The electrochemical measurement can be repeated.

2) Since the film quality is uniform and dense, a fine pattern can be produced.

3) When a highly conductive organic conductive material is used as a raw material, a film having a higher conductivity than an ordinary glassy carbon electrode can be obtained. Therefore, even if it is finely patterned like a comb-shaped electrode, electrochemical The IR drop caused by the high resistance of the substrate during measurement can be reduced.

The advantages such as are obtained. Further, the obtained carbon film has electrochemical properties almost equal to those of a commercially available glassy carbon electrode such as the width of the potential window, and thus is extremely useful as an electrochemical detector for biosensors, liquid chromatography, and flow injection.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view in each step of the production process of the carbon thin film electrode for electrochemical measurement of the present invention, and FIG. 2 is an enlarged perspective view of the carbon thin film electrode prepared in Example 2, FIG. 3 and FIG. FIG. 4 is a schematic cross-sectional view for explaining each state of the material in the manufacturing process of Example 8. 1: Silicon substrate with oxide film 2: Precursor film 3: Conductive carbon film 4: Resist thin film 5: Patterned resist film 6: Microporous electrode 7: Silicon nitride insulating film 8: Platinum / chromium laminated film

Continuation of the front page (56) References JP-A-1-301159 (JP, A) JP-A-63-317758 (JP, A) Actually-opened Shou 61-50263 (JP, U)

Claims (2)

(57) [Claims] 1. An insulating substrate, a conductive material formed directly on the insulating substrate, or by forming an electrically conductive film between the insulating substrate and the insulating substrate to cover the entire surface or a pattern. Of the conductive carbon thin film and the conductive carbon thin film,
Alternatively, in a method for producing an electrochemical measurement electrode comprising a patterned insulating film that partially covers, a method of coating a conductive carbon thin film on a substrate, a spin coating method, an electrolytic polymerization method,
Or after the polymer thin film is formed by the casting method,
A method for producing a carbon thin film electrode for electrochemical measurement, characterized by being produced by being carbonized by heating. 2. An insulating substrate, a conductive material formed directly on the insulating substrate, or by forming an electrically conductive film between the insulating substrate and the insulating substrate to cover the entire surface or a pattern. Of the conductive carbon thin film and the conductive carbon thin film,
Alternatively, in a method of manufacturing an electrochemical measurement electrode comprising a patterned insulating film that partially covers, a polymer thin film is formed on a substrate by a coating method, a spin coating method, or a casting method, and then a sputtering method, or A method for producing a carbon thin film electrode for electrochemical measurement, characterized in that a conductive carbon thin film is produced by a CVD method.