JP2011080773A - Method for manufacturing electrode for electrochemical sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for an electrochemical sensor used in an electrochemical detector, capable of simply and accurately detecting a detection target, while keeping conventional detection sensitivity. <P>SOLUTION: A cylindrical straight pore canal having a uniform pore diameter is formed on an insulating membrane to form a filter membrane, by using at least one among a track-etching method, a photolithographic method, a punching method, a replica method and a laser method. Subsequently, at least one among sputtering method, vapor deposition method, plating method and printing method is applied to the surface of the filter membrane and forms a conductive membrane. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an electrode for an electrochemical sensor, and in particular, a filtration membrane having a smooth surface, a cylindrical and straight pore path, and a uniform pore diameter, and an electrode formed by forming a conductive film on the surface. The manufacturing method of the electrode for electrochemical sensors which has these.

  An analysis method in which electrodes are multiplexed is a useful means for detecting electrode reaction products and reaction intermediates and for obtaining information on reaction rate. For example, in the rotating ring disk electrode method, convection of the electrolyte is caused by rotating the electrode, and the reaction product at the disk electrode is immediately transported to the ring electrode, and the potentials of the ring and disk are set independently. Thus, the product at the disk electrode can be detected by the ring electrode (Non-patent Document 1).

  On the other hand, a channel flow double electrode has a structure in which a channel is provided in a flow cell and an electrolyte is flowed, and a plurality of electrodes (working electrode and counter electrode) are arranged downstream, and reaction products and reactions at the working electrode. An intermediate is detected at the counter electrode (Non-patent Document 2).

  In any of these methods, a sample solution sufficient to fill the electrolytic cell is required. In addition to the electrode surface area, the sensitivity of detecting the reactants is ½ of the electrode rotation speed (non- Patent Document 3) and the latter depend on the apparent power of 1/3 of the electrolyte in the cell (Non-Patent Document 4).

A. Frumkin, L.M. Nekrasov, B.A. Levich, Ju. Ivanov, “Die and Wender Rotierenden Scheibenelektrode mit elenem ringe zur und er en ren er ench er ench er ench er en er, 1, p84-90 Heinz Gerischer, Ingeborg Mattes, Rainer Brau, "Elektrolyse im str ▲ o ▼ mungskanal Ein verfahren zur untersuchung von reaktions und zwischenprodukten", Journal of Electroanalytical Chemistry, 5-6, November-December 1965, Vol. 10, p553-567 (o represents oumlaut) Akira Fujishima et al., “Electrochemical measurement method (bottom)”, Gihodo Shuppan, 1984, p. 247-269 Noriaki Wakabayashi, Masayuki Takeichi, Masayuki Itagaki, Hiroyuki Uchida, Masahiro Watanabe, "Temperature-dependence of oxygen reduction activity at a platinum electrode in an acidic electrolyte solution investigated with a channel flow double electrode", Journal of Electroanalytical Chemistry, 2, 1 January 2005, Vol. 574, p339-346

  In addition, in order to detect chemically unstable reaction intermediates, it is necessary to reduce the distance between the working electrode and the counter electrode. However, while maintaining the detection sensitivity, that is, while maintaining the surface area of the electrode. There were structural limitations in achieving high functionality.

  Therefore, an object of the present invention is to provide an electrode for an electrochemical sensor used in an electrochemical detection apparatus that can easily and accurately detect a detection target while maintaining conventional detection sensitivity. And

  In order to achieve the above object, the present invention provides a step of forming a filtration membrane by forming a hole having a uniform pore diameter in a cylindrical shape and straight in an insulating film, and a step of forming a conductive film on the surface of the filtration membrane. And a method for producing an electrode for an electrochemical sensor.

  According to the manufacturing method of the present invention described above, a filtration membrane can be formed by forming a cylindrical passage that is cylindrical and straight from a predetermined insulating film and has a uniform pore diameter. Therefore, by using the filtration membrane formed in this way as a filtration membrane for an electrochemical sensor electrode, when the electrochemical sensor electrode is applied to an electrochemical detection device, a detection target in a detection target solution Is forced to flow through the pores of the filtration membrane, so that a simple and accurate detection operation can be performed.

  In addition, since the conductive film is formed on the surface of the filtration membrane having such a pore path, the conductive film is formed not only on the surface of the filtration membrane but also on the inner surface of the pore path of the filtration membrane. Become. Therefore, the detection object comes into contact not only with the conductive film formed on the surface of the filtration membrane, but also with the conductive film formed on the inner surface of the pore passage of the filtration membrane, so the detection sensitivity of the detection object is improved. Thus, the presence or absence of the detection target can be effectively identified.

  Note that in one embodiment of the present invention, the hole path is formed by using at least one of a track etching method, a photolithography method, a punching method, a replica method, and a laser method. Thereby, it is possible to form a filter membrane simply and accurately by forming a cylindrical passage that is cylindrical and straight from the predetermined insulating film described above and has a uniform pore diameter. In particular, the pore size distribution can be suppressed to an extremely narrow range of −20% to 0% with respect to the design value, and a filtration membrane having a pore path with a pore size as designed can be formed. An electrode for a chemical sensor, and further an electrochemical detection device can be obtained.

  In one embodiment of the present invention, the conductive film can be formed using at least one of a sputtering method, an evaporation method, a plating method, and a printing method. According to these methods, a conductive film that satisfies the requirements as described above can be easily formed.

  Furthermore, in one embodiment of the present invention, the conductive film can be at least one of a metal film and an organic conductive film.

  As described above, according to the present invention, there is provided an electrode for an electrochemical sensor used in an electrochemical detection device capable of easily and accurately detecting a detection target while maintaining conventional detection sensitivity. Can be provided.

Schematic sectional view showing the structure of the electrode for electrochemical sensors 1 is a schematic configuration diagram of an electrochemical detection device according to an embodiment of the present invention. The schematic block diagram of the electrochemical detection apparatus in other embodiment of this invention The figure which showed the relationship between the density | concentration of the electrolyte solution in Example 1, and an electric current value The figure which showed the electric current-potential curve about the 1st working electrode in Example 3. The figure which showed the time change curve of the electric current in Example 3. FIG.

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

  The electrochemical sensor electrode of the present invention has, for example, the structure shown in FIG. 1, and FIG. 1 is a schematic cross-sectional view showing the configuration of the electrochemical sensor electrode.

  That is, the electrode 1 for an electrochemical sensor is configured by forming a conductive film 3 on the surface of a filtration membrane 2 having a cylindrical pore and a straight hole and having a uniform pore diameter. is there.

  The filtration membrane 2 used in the present invention is characterized by the formed pores, and has a physical feature that the pore structure is cylindrical and straight and has a uniform pore diameter. Yes.

  The filtration membrane 2 having the pore structure as described above uses at least one of a track etching method, a photolithography method, a punching method, and a laser method for an insulating film, for example, a polymer film such as polycarbonate or polyester. Can be formed.

  The track etching method includes a process of tracking (tracing) with heavy ions of high energy and an etching process for creating a cylindrical hole structure.

  In the tracking process, high-energy heavy ions accelerated by an accelerator penetrate the insulating film to form tracks (trajectories), and the number of tracks (holes per unit area) depends on the number of heavy ions and the film winding speed. (Density) is controlled. Next, in the etching process, the tracked film is immersed in an etching solution, and the track portion is preferentially dissolved to form holes. At this time, the hole diameter is controlled by the etching conditions. The pore diameter of the filtration membrane is obtained as uniform, and the pore path is formed in the thickness direction of the film (perpendicular or substantially perpendicular to the film surface).

  Photolithographic methods include, for example, applying a photocurable resin composition on an insulating film to form a photocurable resin composition layer, and an image corresponding to a hole path to be formed on the photocurable resin composition layer. A mask on which is formed is placed, and the photocurable resin composition layer is cured by irradiating the photocurable resin composition layer with light such as ultraviolet rays from above the mask. Next, the mask is removed, development is performed by dissolving and removing the uncured photocurable resin composition with a developer, and a mask pattern made of the photocurable resin composition is formed by transferring the image of the mask. Form.

  In addition, a material may be used in which a portion irradiated by light generates solubility in a predetermined solvent. In this case, a light beam such as ultraviolet rays is used at a predetermined position using a mask in the same manner as described above. The mask pattern made of the above material is formed by removing the portion irradiated with light with the developer.

  In the mask pattern formed as described above, an opening is formed in a portion corresponding to the hole path. Therefore, the hole path can be formed in the insulating film by performing an etching process through the mask pattern. it can. Also in this case, the hole diameter is obtained as a uniform diameter and is formed in the thickness direction of the insulating film (perpendicular or substantially perpendicular to the surface of the insulating film).

  The etching process may be a wet etching process using an etchant, or may be a dry etching process such as RIE.

  Moreover, as said photocurable resin composition, conventionally well-known arbitrary photocurable resin compositions can be used, for example, a photopolymerizable oligomer, a photopolymerizable monomer (reactive diluent), a photoinitiator, Examples thereof include a photocurable resin composition comprising a photopolymerization initiation assistant, a thermal polymerization inhibitor, a filler, an adhesion imparting agent, a thixotropic agent, a plasticizer, a colorant and the like.

  Examples of the photopolymerizable oligomer include epoxy resins; imide-based oligomers; acrylate-based oligomers such as urethane acrylate, epoxy acrylate, and polyester acrylate; unsaturated polyesters; vinyl ether oligomers;

  As said photopolymerizable monomer (reactive diluent), a monofunctional acrylate monomer, a polyfunctional acrylate monomer, an epoxy monomer, vinyl ether, styrene etc. are mentioned, for example.

  Examples of the photopolymerization initiator include benzoin-based, acetophenone-based, peroxide-based, and onium salt-based photopolymerization initiators. Examples of the photopolymerization initiation assistant include amine-based and quinone-based photopolymerization initiators. Examples include photopolymerization initiation assistants.

  The punching method is a method in which a punch is used as a drilling tool, for example, the insulating film is moved in the X direction, the punch is moved in the Y-axis direction, and a hole is formed by punching a portion where a hole path is to be formed. is there. Further, the hole can be easily formed by fixing the insulating film, moving the punch in the X direction and the Y direction, and performing punching at a position where a hole path is to be formed.

  The replica method is a method obtained by pouring a resin or the like into an uneven mold and curing it. The shape, size, and density of the holes to be transferred to the material can be adjusted according to the shape, size, and density of the unevenness. Further, in order to obtain a filtration membrane as in the present invention, it is necessary to prepare a mold having minute irregularities, and a porous alumina film or a mesoporous silica film obtained by an anodic oxidation method or the like can be used as a template. it can.

  The laser method is a method in which a hole is formed by ablation by irradiating the insulating layer with laser light. As such a laser light source, for example, an excimer laser or a YAG laser can be used, but other light sources may be used. Laser light emitted from these laser light sources is converted into parallel light through a collimator lens, and then the beam diameter is reduced by an objective lens in accordance with the hole diameter of the hole path to be formed, and then irradiated onto the insulating film. . As a result, the portion of the insulating film irradiated with the laser light beam is ablated, and the above-described hole path is formed.

  Note that an ultraviolet absorber or a dye may be added to the insulating film in order to increase the absorption efficiency of laser light and make the formation of the through hole more accurate and easy. For example, if 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-dibenzotriazole having an absorption region at 300 to 400 nm and a maximum absorption wavelength at 346 nm is used. The absorption efficiency of the ND-YAG triple wave laser having a wavelength of 355 nm or the excimer Xe-F laser having a wavelength of 352 nm can be further increased, and the through hole can be formed more accurately and easily.

  As the ultraviolet absorber, any ultraviolet absorber generally used as an ultraviolet absorber for polymer resins can be used, for example, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxy. Benzophenone, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy) -3′-tert-butyl-5′-methylphenyl) chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2 '-Hydroxy-3'-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylpheny (Benzotriazole, 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl) phenol, and the like.

  Further, when the wavelength of the laser to be used is in the visible light region, the absorption efficiency of the laser light can be further increased by adding a dye. The dye to be added preferably has a large absorption rate of the laser light wavelength to be used. Porphyrin dye, coumarin dye, pyrazole azo dye, porphycene dye, cyanine dye, merocyanine dye, phthalocyanine dye, azo dye A dye, a spiropyran dye, a fluorane dye, a quinone dye, a substituted benzene dye, or the like is used.

  If the addition amount of the ultraviolet absorber and the dye is too small, the absorption efficiency is poor, and if the addition amount is too large, the absorption efficiency is too good and the absorption site is localized. Therefore, 100 weight of the material constituting the insulating layer The amount is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 3 parts by weight with respect to parts.

  When pores are formed in the insulating film based on the method as described above, it will be described in comparison with a conventionally used filtration membrane. For example, even when both filtration membranes have a nominal pore diameter of 1 μm, conventional filtration is used. Whereas the pore size distribution of the membrane extends to 0.1 to 10 μm, the pore size distribution is 0.8 to 0.8 when the pore path is cylindrical and straight, as in the filtration membrane of the present invention. 1 μm (−20% to 0%) and very sharp.

  Moreover, when comparing the aperture ratio between the filtration membrane 2 used in the present invention and the conventional filtration membrane, the aperture ratio of the conventional filtration membrane is 50% or more, or 70 to 90%. Porosity is as small as less than 15%.

The filtration membrane 2 used in the present invention has a thickness of 6 to 11 μm, a porosity of less than 15%, a pore density of 1 × 10 ^{5 to} 6 × 10 ⁸ pieces / cm ² , and a pore diameter of 0.015 to Those having a size of 12.0 μm are known, and these can be used as appropriate, and are preferably used according to the purpose. The lower limit of the opening ratio is not particularly limited, but it preferably has an opening ratio of at least several percent in order to function as a filtration membrane.

  Further, since the filtration membrane 2 can be formed of, for example, a polymer film as described above, the surface thereof can be made smooth, that is, the surface roughness Ra = 1 μm or less. In addition, Ra here shows arithmetic mean height and is based on JISB0601-2001.

  A conductive film 3 is formed on the surface of the filtration membrane 2 to form an electrode for an electrochemical sensor. At this time, the conductive film 3 is made of a metal film such as platinum or gold, a film such as graphite carbon or boron-doped diamond, It can be set as the polymer film by electroconductive polymers, such as polyaniline and polythiophene.

  In order to form such a conductive film 3 on the filtration film 2, it can be formed by sputtering, vapor deposition, plating, printing, or the like.

  The sputtering method uses a glow discharge generated by preparing a target such as platinum described above and setting the target at a negative potential in a reduced pressure atmosphere, and sputter ions such as argon ions contained in the discharge collide with the target. Thus, the target material separated from the target is attached to form the target film, in this embodiment, the conductive film 3.

  The vapor deposition method prepares a vapor deposition source such as platinum described above, vaporizes the vapor deposition source by irradiating the vapor deposition source with, for example, an electron beam, and attaches the vaporized vapor deposition source to the target film. In the form, the conductive film 3 is formed.

In the plating method, the compound containing platinum or the like (PtCl ₂ or the like) is decomposed in a plating bath by electrolysis or no electric field to deposit platinum (Pt) or the like, and the target film, in this embodiment, the conductive film 3 is formed. To form.

  In the printing method, the above-described material constituting the conductive film 3 is mixed with a binder, a solvent, or the like to prepare a coating solution. After coating the coating solution, the binder is heated to decompose and disappear, and the solvent or the like is vaporized. Thus, the target film, in this embodiment, the conductive film 3 is formed.

  Typical examples of printing methods include spin coating methods, but also, ink jet printing, screen printing, dispenser printing, letterpress printing (flexographic printing), sublimation printing, offset printing, laser printer printing (toner printing), intaglio. Examples include printing (gravure printing), contact printing, microcontact printing, and the like.

  If the conductive film 3 is a metal film, any of the above-described methods can be used. However, in the case of a conductive polymer, it is difficult to form the conductive film 3 by a plating method. Instead, it can be formed by chemical modification or the like.

  In addition, the thickness of the filtration membrane in this electrochemical sensor electrode is preferably 1 to 500 μm, and particularly preferably 1 to 100 μm. The thickness of the conductive film is preferably 0.001 to 0.5 μm, but is not particularly limited as long as the conductivity can be stably maintained.

  Further, the filtration membrane is not particularly limited as long as its structure can detect the detection target. For example, the filtration membrane may be a normal flat membrane shape, or a pleated shape for increasing the filtration area. The filter cartridge may be processed into a flat film, but is preferably a flat membrane.

  Next, an electrochemical sensor using the electrochemical sensor electrode, an electrochemical detection apparatus and a detection method using the electrochemical sensor will be described.

  The electrochemical sensor has a cylindrical and straight pore path, an electrode for an electrochemical sensor that forms a conductive film on the surface of a filtration membrane having a uniform pore diameter, and a uniform and uniform pore path that is cylindrical and straight. The electrode for electrochemical sensor which becomes a counter electrode which formed the electrically conductive film on the surface of the filtration membrane which has an appropriate hole diameter, and is piled up so that these electrodes for electrochemical sensors may not be short-circuited.

  That is, this electrochemical sensor is constituted by stacking a plurality of electrodes for electrochemical sensors of the present invention, and the electrodes are not short-circuited at that time. For example, FIGS. 2 and 3 show schematic configuration diagrams of the electrochemical detection apparatus. Among them, the electrochemical sensor is represented by 11 in FIG. 2 and 12 in FIG.

  For example, the electrochemical sensor 11 shown in FIG. 2 includes an electrochemical sensor electrode 11A serving as a working electrode and an electrochemical sensor electrode 11B serving as a counter electrode.

  At this time, the electrodes 11A and 11B for the electrochemical sensor are for the electrochemical sensor so that the electrode 11A for the electrochemical sensor faces upward (the conductive film is on the detection target solution supply unit 25 side) so that the electrodes do not short-circuit each other. It is preferable to overlap the electrodes 11B facing downward (the conductive film is on the suction part 26 side). In addition, any electrode can be applied without particular limitation as long as the electrodes are not short-circuited without blocking the hole paths of the electrodes. For example, there is a gap between the electrodes 11A and 11B for electrochemical sensors. And a method of inserting an insulating film or the like as a spacer.

  The electrochemical sensor 12 shown in FIG. 3 has an electrochemical sensor electrode 12A as a first working electrode, an electrochemical sensor electrode 12B as a second working electrode, and an electrochemical sensor electrode as a counter electrode. And electrode 12C.

  At this time, the electrochemical sensor electrodes 12A, 12B, and 12C are electrochemically placed so that the electrochemical sensor electrode 12A faces upward from above (the conductive film is on the detection target solution supply unit 35 side) so that the electrodes are not short-circuited. The sensor electrode 12B is directed upward (the conductive film is on the detection target solution supply unit 35 side) and the electrochemical sensor electrode 12C is directed downward (the conductive film is on the suction unit 36 side), and further overlapped with the electrochemical sensor 12A. A short circuit is prevented by overlapping the spacer 12D with the spacer 12D. As this spacer 12D, it is preferable to use the filtration membrane used as a base material in the electrode for an electrochemical sensor of the present invention.

  Next, an electrochemical detection apparatus and method will be described.

  As described above, the electrochemical detection device includes, for example, the one shown in FIGS. 2 and 3.

  First, the electrochemical detection device 21 shown in FIG. 2 will be described. The electrochemical detection device 21 includes an electrochemical sensor 11, a potential control unit 22, a current measurement unit 23, a reference electrode 24, a detection target solution supply unit 25, and a suction unit 26. It is.

  The electrochemical sensor 11 is as described above. In the electrochemical sensor 11, the electrodes 11 </ b> A and 11 </ b> B are connected to the potential control means 22. The potential control means 22 applies a potential to the electrodes connected in this way, and further has a function of making this potential difference constant. For example, a potentiostat can be mentioned. A function generator may be used for the potentiostat. Further, the current measuring means 23 is connected to the potential control means 22 composed of a potentiostat in this way, and the change in the current value due to the oxidation or reduction of the detection object on the working electrode can be measured and recorded. It is like that. A reference electrode 24 is connected to the potential control means 22, and the reference electrode 24 serves as an electrode serving as a reference when determining the potential of the working electrode, and a saturated calomel (mercury) electrode, a silver electrode, or the like is used.

  The electrochemical detection device 21 includes a detection target solution supply unit 25 on the working electrode side and a counter electrode side so that the electrochemical sensor 11 can be passed while supplying the detection target solution to the electrochemical sensor 11. The suction part 26 is provided so as to sandwich the electrochemical sensor 11.

  In the electrochemical detection method using the electrochemical detection device 21, the electrochemical sensor electrode 11A serving as a working electrode and the electrochemical sensor electrode serving as a counter electrode while passing a detection target solution through the electrochemical sensor 11 are used. A predetermined voltage is applied between 11B by the potential control means 22 so as to provide a potential difference. At this time, a predetermined potential is set while referring to the potential of the reference electrode 24.

  In the detection target solution including the detection target in a state where the predetermined potential is provided as described above, the detection target approaches the surface of the conductive film of the electrochemical sensor electrode 11A serving as the working electrode or the side surface of the hole. Then, the exchange of electrons causes an oxidation or reduction reaction, and the change in the current value at that time can be measured to determine the presence or absence of the detection target, calculate the abundance, and the like. The electrode 11A for an electrochemical sensor serving as the working electrode is composed of the electrode 1 for an electrochemical sensor, the surface of the filtration membrane 2 serving as the base material is smooth, and the pore path is cylindrical and straight. Since the pore diameter is uniform, the detection target in the detection target solution is forced to flow through the pores of the filtration membrane, and the detection operation can be performed easily and accurately. It is.

  Moreover, it is thought that the electrically conductive film 3 formed in the surface forms the electrically conductive film 3 also in the side surface of the hole path 4 in addition to the surface of the filtration membrane 2 (refer FIG. 1). This is also the case where when the filtration operation is performed using the electrochemical sensor electrode 11A serving as the working electrode, when the detection object passes through the perforation 4, the conductive film formed on the surface of the permeation membrane or on the side of the perforation. It is considered that the presence / absence of the detection target can be effectively detected because the film 3 always approaches the film 3.

  In addition, since detection is performed by passing through such minute holes, the diffusion distance of the detection target in the solution to the electrode surface is reduced, and the oxidation-reduction reaction proceeds effectively. In ripping voltammetry, the time required for pre-electrolysis can be suppressed as compared with the conventional method, and the detection result can be obtained quickly.

  Here, the detection target is an electroactive material that can be measured by stripping voltammetry, which is electrochemical measurement, and may be any material that is deposited on the electrode surface by an oxidation-reduction reaction. And metal ions.

  Moreover, the solvent of the solution to be detected may be any solvent as long as it can be measured by stripping voltammetry, which is electrochemical measurement. Usually, an electrolyte is used, and examples thereof include an aqueous potassium chloride solution.

  Since the potential difference between the working electrode and the counter electrode applied when performing the detection operation is specific to the object to be detected, it is necessary to adjust it accordingly. That is, the detection target object undergoes oxidation or reduction reaction on the working electrode, but even if other substances are included, the detection target object can be accurately measured without being detected.

  Next, the electrochemical detection device 31 shown in FIG. 3 will be described. The electrochemical detection device 31 includes an electrochemical sensor 12, a potential control unit 32, a current measurement unit 33, a reference electrode 34, a detection target solution supply unit 35, and a suction unit 36. It is.

  The electrochemical sensor 12 is as described above. In the electrochemical sensor 12, the electrodes 12 </ b> A, 12 </ b> B, and 12 </ b> C are connected to the potential control means 32. The potential control means 32 applies a potential to the electrodes connected in this way, and further has a function of making this potential difference constant, and examples thereof include a bipotent stat. A function generator may be used for the bipotentiostat. Further, the current measuring means 33 is connected to the potential control means 32 composed of a bipotentiostat in this way, and the change in the current value due to the oxidation or reduction of the detection object on the working electrode can be measured and recorded. It can be done. A reference electrode 34 is connected to the potential control means 32, and the reference electrode 34 serves as a reference electrode when determining the potential of the working electrode, and a saturated calomel (mercury) electrode, a silver electrode, or the like is used.

  The electrochemical detection device 31 includes a detection target solution supply unit 35 on the working electrode side and a counter electrode side so that the electrochemical sensor 12 can be passed while supplying the detection target solution to the electrochemical sensor 12. The suction part 36 is provided so as to sandwich the electrochemical sensor 12. At this time, a cover 37, a guard column, or the like may be provided between the electrochemical sensor electrode 12A serving as the first working electrode and the detection target solution supply unit 35 to prevent electrode deterioration due to clogging or the like.

  In the electrochemical detection method using the electrochemical detection device 31, an electrochemical sensor electrode 12A serving as a first working electrode and an electrochemical serving as a counter electrode while passing a detection target solution through the electrochemical sensor 12. A predetermined potential difference is provided by the potential control means 32 between the sensor electrode 12C, the electrochemical sensor electrode 12C serving as the second working electrode 12B, and the electrochemical sensor electrode 12C serving as the counter electrode. At this time, a predetermined potential is set while referring to the potential of the reference electrode 34.

  Here, the detection operation is basically performed by the same operation as that of the electrochemical detection device 21, and the difference is that two working electrodes are provided. Thus, by providing a plurality of working electrodes, working electrodes having different potential differences can be produced. By using working electrodes with different potential differences, it is possible to detect a plurality of detection objects in the same solution with a single operation, and to detect and observe chemically unstable substances. it can.

  Further, in the conventional measurement, it is possible to confirm the presence of an intermediate substance that could not be confirmed when the two-step reaction is extremely fast due to the limit of the detection speed. This is because the filtration membrane used in the present invention is very thin, so that the distance between the first working electrode and the second working electrode can be shortened, and the electrochemical detection device of the present invention is extremely excellent. It is a thing.

  As described above, the electrode for an electrochemical sensor of the present invention has a uniform cylindrical straight hole of the order of several tens of nanometers to micrometers, has a smooth surface, and has a thickness of several microns to about 10 microns. It is characterized by being extremely thin, and it is a new electrochemical detection that exceeds the conventional structural limit by measuring multiple objects by using multiple layers to form an electrochemical sensor and measuring the object to be detected. Apparatus and methods can be provided.

  A plurality of electrodes for electrochemical sensors serving as working electrodes are used in an overlapping manner, and a potential is set independently, thereby realizing a multiple electrode having extremely high detection sensitivity. An appropriate spacer is inserted between the electrodes as required, and the electroactive material is detected while controlling the flow rate of the electrolyte from the working electrode to the counter electrode.

  The flat membrane type microchannel platinum electrode has a large surface area as the electrode because it is coated with platinum to the inside of the pores of the filtration membrane. Furthermore, the forced flow of the electrolyte to the pores of the filtration membrane causes the reactants to flow onto the electrode surface. Since the transport is promoted, the reaction efficiency is excellent, and the electroactive material can be detected with high sensitivity. In addition, since this electrode has a feature that it is extremely thin, in a multiple electrode produced by stacking a plurality of electrodes, a substance generated at the working electrode can instantaneously reach the counter electrode (several microseconds to several tens of microseconds). Therefore, it becomes easy to achieve high functionality while maintaining excellent sensitivity.

  Next, examples of the present invention will be described.

(Example 1) Confirmation of detection sensitivity of electrochemical sensor The surface of each of four types of Nuclepore membrane filters (manufactured by Whatman) having a diameter of 47 mm different from 0.4 μm, 1.0 μm, 3.0 μm and 5.0 μm in pore diameter In addition, using an auto fine coater (manufactured by JEOL Ltd., trade name: JFC-1600), platinum is vacuum-deposited for 300 seconds under the condition of a sputtering current of 40 mA for an electrochemical sensor having a platinum thickness of 0.1 μm. An electrode was produced.

  The obtained electrode for an electrochemical sensor is used as a working electrode, and the one used as a counter electrode is stacked on top of the other, and the one used as a counter electrode is laminated with the deposition surface facing down, and a filter holder for vacuum filtration (manufactured by ADVANTEC, product Name: KG-25 type, 160 mL capacity funnel was used), and each electrode was connected to potentiostat / galvanostat (Hokuto Denko, trade name: HA1010 mM 2B type). Silver / silver chloride was used as the reference electrode, and the tip of the salt bridge was set at the top of the working electrode at a position of about 1 mm (see FIG. 2). When the working electrode is manufactured using a filtration membrane having a pore size of 5.0 μm, a filtration membrane having a pore size of 5.0 μm is used. When the working electrode is manufactured using a filtration membrane having a pore size of 0.4 μm, the pore size is 0.4 μm. The filtration membrane having the same pore diameter was used for the working electrode and the counter electrode so that the filtration membrane was used as a filtration membrane for the counter electrode.

The electrolytic solution is 1.0 × 10 ^{−9 to} 1.0 × 10 ⁻⁴ mol · dm ⁻³ potassium hexacyanoferrate (II) aqueous solution (containing 0.1 M KCl as a supporting electrolyte), and the flow rate is The relationship between the concentration of hexacyanoferrate (II) ion and the current value was examined while fixing the potential of the working electrode at 15 mL · min ⁻¹ and +0.6 V.

As a result, as shown in FIG. 4, it was confirmed that there is a good correlation between the concentration of hexacyanoferrate (II) ions and the current value, and that the current sensitivity increases as the pore diameter of the working electrode decreases. did. When a working electrode having a pore diameter of 0.4 μm was used, a stable current value was obtained when the concentration of hexacyanoferrate (II) ion was 1.0 × 10 ⁻⁷ mol · dm ⁻³ or more. At this time, the current value with respect to 1.0 × 10 ⁻⁷ mol · dm ⁻³ was 2.6 ± 0.7 μA.

  This value corresponds to a detection signal that is about 50 times as large as the limit current value of a normal rotating Pt disk electrode (2000 rpm) is around 0.05 μA.

(Example 2) Confirmation of detection rate (capture rate) of an electroactive material in an electrochemical sensor An auto fine coater (Nippon Denshi Co., Ltd.) on the surface of a new clip pore membrane filter (manufactured by Whatman) having a pore size of 0.4 μm and a diameter of 47 mm Using a product made by the company, trade name: JFC-1600), platinum was vacuum-deposited for 300 seconds under the condition of a sputtering current of 40 mA to produce an electrochemical sensor electrode having a platinum thickness of 0.1 μm.

  The obtained electrochemical sensor is used as a working electrode, the deposition surface is up, and the counter electrode is used as a counter electrode, with two deposition layers facing down, and a vacuum filtration filter holder (manufactured by ADVANTEC, trade name: Each electrode was connected to a potentiostat / galvanostat (made by Hokuto Denko, trade name: HA1010 mM2B type). Silver / silver chloride was used as the reference electrode, and the tip of the salt bridge was set at the top of the working electrode at a position of about 1 mm (see FIG. 2).

The electrolyte was 100 mL of a 1.0 × 10 ⁻⁵ mol · dm ⁻³ aqueous solution of potassium hexacyanoferrate (II) (containing 0.1 M KCl as a supporting electrolyte), and the flow rate was 7.1 and 18 mL · min. ^In step ⁻¹ , the potential of the working electrode was fixed at +0.6 V, and the amount of electricity was calculated from the oxidation current of potassium hexacyanoferrate (II) to obtain the capture rate on the electrode surface.

As a result, the capture rates were 63 and 44%, respectively, at a flow rate of 7.1 and 18 mL · min ⁻¹ . This is a value sufficient to enable high-sensitivity analysis by stripping voltammetry.

In a normal stripping method using a mercury drop electrode, for example, when the concentration of metal ions is 10 ⁻⁷ to 10 ⁻⁹ mol · dm ⁻³ , pre-electrolysis for several minutes to 60 minutes is required. Since the time required for filtration itself corresponds to the time for pre-electrolysis, if a 100 mL sample is processed at a flow rate of 10 mL · min ⁻¹ , it will be completed in 10 minutes, and the time required per sample compared to the conventional method It will be greatly shortened.

Example 3 Confirmation of Redox Cycle in Electrochemical Sensor Double Electrode A fine clipper membrane filter (manufactured by Whatman) having a pore diameter of 5.0 μm and a diameter of 47 mm was applied to an auto fine coater (manufactured by JEOL Ltd., trade name: JFC-). 1600), platinum was vacuum-deposited for 300 seconds under the condition of a sputtering current of 40 mA to produce an electrochemical sensor electrode having a platinum thickness of 0.1 μm.

  In order from the top, cover (unmodified filtration membrane), platinum electrode (first working electrode (WE1)), spacer (unmodified filtration membrane), platinum electrode (second working electrode (WE2)), platinum electrode (Counterelectrode) are stacked and sandwiched between filter holders for vacuum filtration (ADVANTEC, KG-25, 160 mL capacity funnel), and each electrode is bipotentiostat (Hokuto Denko, trade name: HA1010 mM 2B) ). Silver / silver chloride was used as the reference electrode, and the tip of the salt bridge was set at the top of the working electrode at a position of about 1 mm (see FIG. 3). As the function generator, HB-111 type, manufactured by Hokuto Denko Co., Ltd., was used.

The electrolyte was a 1.0 × 10 ⁻⁴ mol · dm ⁻³ potassium hexacyanoferrate (II) aqueous solution (containing 0.1 M KCl as a supporting electrolyte), and the flow rate was 8.6 mL · min ⁻¹ . The potential of WE1 was swept at 50 mV · s ⁻¹ in the range of 0 to +0.7 V to obtain a current-potential curve. Note that the potential of WE2 at this time was fixed to + 0.1V. The results are shown in FIG. The horizontal axis is the potential of WE1. The potential of WE1 is 0.3 V vs. An anode current due to oxidation of hexacyanoferrate (II) ions is observed at Ag / AgCl or higher, and a cathode current is observed at WE2 accordingly. That is, it shows that the hexacyanoferrate (II) ion generated in WE1 is reduced in WE2. A curve of this time change is shown in FIG. The cathode current at WE2 corresponds to the change in the anode current of WE1, and a redox cycle at the double electrode could be observed.

  From the above results, according to the electrochemical detection apparatus and method of the present invention, the detection target can be measured easily and accurately, and by providing a plurality of working electrodes, a plurality of reactions can be performed by a single detection operation. It can be seen that detection is possible.

  DESCRIPTION OF SYMBOLS 1 ... Electrochemical sensor electrode, 2 ... Filtration membrane, 3 ... Conductive film, 11, 12 ... Electrochemical sensor, 11A ... Electrochemical sensor electrode used as a working electrode, 11B ... Electrochemical sensor electrode used as a counter electrode, 12A ... Electrochemical sensor electrode as a first working electrode, 12B ... Electrochemical sensor electrode as a second working electrode, 12C ... Electrochemical sensor electrode as a counter electrode, 12D ... Spacer, 21 ... Electrochemical detection Device: 22 ... Potential control means, 23 ... Current measurement means, 24 ... Reference electrode, 25 ... Detection target solution supply part, 26 ... Suction part, 31 ... Electrochemical detection device, 32 ... Potential control means, 33 ... Current measurement Means 34... Reference electrode 35. Detection target solution supply unit 36 36 Suction unit 37 37 Cover

Claims (5)

A step of forming a filtration membrane by forming a hole with a uniform pore diameter in a cylindrical shape and straight on the insulating membrane;
Forming a conductive film on the surface of the filtration membrane;
A method for producing an electrode for an electrochemical sensor, comprising:   2. The method of manufacturing an electrode for an electrochemical sensor according to claim 1, wherein the hole path is formed using at least one of a track etching method, a photolithography method, a punching method, a replica method, and a laser method. Method.   The method for producing an electrode for an electrochemical sensor according to claim 1 or 2, wherein the conductive film is formed using at least one of a sputtering method, a vapor deposition method, a plating method, and a printing method.   The method for producing an electrode for an electrochemical sensor according to any one of claims 1 to 3, wherein the conductive film is at least one of a metal film and an organic conductive film.   The method for producing an electrode for an electrochemical sensor according to any one of claims 1 to 4, wherein the pore size distribution of the filtration membrane is in a range of -20% to 0% with respect to a design value. .

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