JP2020056750A - Working electrode for taste sensor, taste sensor including working electrode and manufacturing method of working electrode - Google Patents

Abstract

To provide a working electrode which can be manufactured at low cost and has little variation in a potential response amount, a manufacturing method of the working electrode, and a taste sensor including the working electrode.SOLUTION: There is provided a working electrode covering an insulating support substrate, and comprising a laminate in which (i) an electrode layer including an electrolyte salt-containing electrode layer and (ii) a waterproof insulating layer are laminated in this order and a taste detection membrane embedded in the waterproof insulating layer. In the working electrode, the electrolyte salt-containing electrode layer includes at least a mixture of (a) Ag particles and (b) specific alkali metal salt particles or alkaline earth metal salt particles, the components (a) and (b) are present as a porous solid particle mixture mass, the taste detection membrane has a surface contacting an object to be measured, and the taste detection membrane is in electrical contact with the electrolyte salt-containing electrode layer. There are also provided a manufacturing method of the working electrode; and a taste sensor including the working electrode.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a taste sensor, and more particularly to a working electrode for a taste sensor.

  Quantifying the taste, which is one of the five senses of human beings, can provide an objective index when examining high value-added foods or controlling the quality of food production. There is a high interest.

  However, the conventional taste sensor (see, for example, FIGS. 7 and 9 of Patent Document 4) has a large and expensive device, and depends on the type of taste to be measured (saltiness, acidity, bitterness, umami, astringency, etc.). There is a problem that much cost and labor are required, such as the necessity of preparing an expensive sensor head, the cleaning labor required for repeated use of the sensor head, and the necessity of preparing a large number of measurement samples.

  For this reason, various studies have been made to reduce the size (chip) and cost of the taste sensor (Patent Documents 1 to 3).

JP-A-7-103934 JP 2007-57459 A JP 2012-83314 A JP 2007-217630 A

  However, it can be manufactured inexpensively enough to make disposable use sufficiently possible, and there is little variation in the amount of potential response (variation over time after manufacture and variation between products) so that the measurement operation can be greatly simplified. There is a further need for a taste sensor, particularly a working electrode that can construct such a taste sensor.

An example (first aspect) of the means for solving the problem of the present invention is:
Covering the insulating support substrate,
(I) an electrode layer including an electrolyte salt-containing electrode layer;
(Ii) a laminate in which a waterproof insulating layer is laminated in this order;
A taste detection membrane embedded in the waterproof insulating layer, and a working electrode,
At least the electrolyte salt-containing electrode layer,
(A) Ag particles;
(B) a mixture with alkali metal salt particles or alkaline earth metal salt particles,
The components (a) and (b) are present as a porous solid particle mixture mass;
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- is selected from the group consisting of, ^- and SCN
A working electrode, wherein the taste detection membrane has a surface for contacting an object to be measured, and is in electrical contact with the electrolyte salt-containing electrode layer.

Here, the electrolyte salt-containing electrode layer further comprises:
(C) containing an AgX _C salt,
X _C ^{- ions, Cl -, Br -, I} - and SCN ^- is preferably selected from the group consisting of.

Further, the electrode layer covers the insulating support substrate, and further includes a support electrode layer,
The electrolyte salt-containing electrode layer is formed on the support electrode layer,
The supporting electrode layer is made of a conductive material such as C (carbon), Ag (silver), a mixture of C (carbon) and Ag (silver), a mixture of Ag and AgX _D salt, and a mixture of C (carbon), Ag and AgX. _D, comprising one selected from the group consisting of a mixture with a salt,
X _D ^{- ions, Cl -, Br -, I} - and SCN ^- is preferably selected from the group consisting of.

  Further, it is preferable that the alkali metal salt particles or alkaline earth metal salt particles include potassium chloride (KCl) particles.

  Further, it is preferable that the taste detecting film is a bitterness detecting film or a bitterness detecting film.

  Another example (second aspect) of the means for solving the problem of the present invention is a flat plate type taste sensor including the working electrode of the first aspect and a reference electrode.

Still another example (third aspect) of the means for solving the problem of the present invention is a method for manufacturing a working electrode according to the first aspect,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an electrolyte salt-containing electrode layer over the insulating support substrate,
(A) Ag particles;
(B) alkali metal salt particles or alkaline earth metal salt particles;
(C) after applying a mixture paste containing at least a dispersant, and heating and drying to form the electrolyte salt-containing electrode layer,
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) electrically contacting the electrolyte salt-containing electrode layer to form a taste detecting film having a surface for contacting an object to be measured so as to fill the opening for film formation. .

Here, the mixture paste further comprises:
(D) comprising an AgX _C salt,
X _C ^{- ions, Cl -, Br -, I} - and SCN ^- is preferably selected from the group consisting of.

Further, the step (ii) comprises:
(Ii-1) a step of applying a conductive material-containing paste on the insulating support substrate to form a support electrode layer;
(Ii-2) forming the electrolyte salt-containing electrode layer by applying the mixture paste on the support electrode layer and then heating and drying the mixture paste;
It is preferable to include

Still another example (fourth aspect) of the means for solving the problem of the present invention is a method for manufacturing a working electrode according to the second aspect,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an Ag electrode layer over the insulating support substrate,
(A) Ag particles;
(B) applying a mixture paste containing a dispersant, followed by heating and drying to form the Ag electrode layer;
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) a step of adding a solution of an alkali metal salt or an alkaline earth metal salt to the Ag electrode layer portion in the film forming opening and drying the Ag electrode layer portion to form an electrolyte salt-containing electrode layer. So,
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(V) electrically contacting the electrolyte salt-containing electrode layer to form a taste detecting film having a surface for contacting an object to be measured so as to fill the opening for film formation. .

  The working electrode of the present invention has a structure that can be easily and inexpensively manufactured by a printing method, and can be easily applied to a single-plate, multi-channel taste sensor (see FIG. 10).

  Further, since a wetting layer such as a polymer gel is not required, a structure advantageous for suppressing variation in the potential response amount over time after manufacturing can be obtained.

  In addition, the presence of the electrolyte salt-containing electrode layer used in the present invention can suppress variations in the potential response amount for each product.

  For this reason, for example, when used as a disposable taste sensor in combination with an appropriate reference electrode, a preset reference liquid potential response amount is used instead of the conventional relative potential method (two liquid measurement of the reference liquid measurement and the sample liquid measurement). By using the absolute potential method (one-solution measurement of only the sample solution) used, the measurement operation can be greatly simplified.

  Further, when used as a disposable taste sensor, it is not required to be used repeatedly, so that there is an advantage that washing is unnecessary and measurement can be performed in a short time.

It is sectional drawing which shows an example of the basic structure of the working electrode of this invention. The plan view (a) of the working electrode of invention products 1 and 6 and the sectional view (b) by the plane perpendicular to the paper and passing through the line A-A 'are shown. The plan view (a) of the working electrode of invention products 2 to 5 and the sectional view (b) by a plane perpendicular to the paper and passing through a line segment A-A 'are shown. A plan view (a) of the working electrode of the comparative product 4 and a sectional view (b) of a plane perpendicular to the paper and passing through a line segment A-A 'are shown. The plan view (a) of the working electrode of the comparative products 1-3 and 5-6, and the sectional view (b) by the plane which is perpendicular to the paper surface and passes through the line A-A 'are shown. It is a figure which shows the relationship between the elapsed days after production | generation and electric potential change about each working electrode of invention product 1 and comparative product 1. The relationship between the concentration of the bitter component (horizontal axis) and the potential (based on Ag / AgCl, vertical axis) and the variation of the potential (error bar) for the working electrodes of Invention Product 1 and Comparative Product 1 are shown. FIG. FIG. 8 is a diagram in which the potential on the vertical axis in FIG. 7 is replaced with a potential response amount (the difference between the potential of a predetermined bitter substance concentration and the zero potential of a bitter substance). It is a figure which shows the relationship between the lipid concentration in the film | membrane for taste detection, and the variation of the electric potential response amount about each working electrode of the invention product 1 and the comparative product 1. It is an example of a taste sensor having a plurality of electrodes on one substrate. For example, one of the electrodes can be used as a reference electrode, and the other electrode can be used as a working electrode of the present invention.

[A. Regarding the first embodiment of the present invention]
The first aspect of the present invention,
Covering the insulating support substrate,
(I) an electrode layer including an electrolyte salt-containing electrode layer;
(Ii) a laminate in which a waterproof insulating layer is laminated in this order;
A taste detection membrane embedded in the waterproof insulating layer, and a working electrode,
At least the electrolyte salt-containing electrode layer,
(A) Ag particles;
(B) a mixture with alkali metal salt particles or alkaline earth metal salt particles,
The components (a) and (b) are present as a porous solid particle mixture mass;
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- is selected from the group consisting of, ^- and SCN
A working electrode, wherein the taste detection membrane has a surface for contacting an object to be measured, and is in electrical contact with the electrolyte salt-containing electrode layer.

(A-1) Electrode layer The electrode layer includes an electrolyte salt-containing electrode layer,
The electrolyte salt-containing electrode layer, at least,
(A) Ag particles;
(B) a mixture with alkali metal salt particles or alkaline earth metal salt particles,
The components (a) and (b) are present as a porous solid particle mixture mass;
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- is selected from the group consisting of ^- and SCN.

(A)
In the electrolyte salt-containing electrode layer, Ag particles and specific alkali metal salt particles or alkaline earth metal salt particles are present as a porous solid particle mixture mass. From the viewpoint of potential stability, the solid particle mixture or the solid particle mixture mass may optionally further include AgX _C salt particles (X _C ^- ions are selected from the group consisting of Cl ⁻ , Br ⁻ , I ^−, and SCN ^−). ) May be included. Incidentally, X _A in the present application ^- ion, X _B ^- ion, X _C ^- ions or X _D, ^- ions is simply X ^- sometimes referred ions.

  It is considered that when the aqueous solution to be measured comes in contact with the taste detection membrane, an electrolyte salt layer using the water of the aqueous solution as a medium is quickly formed on the electrolyte salt-containing electrode layer. That is, water enters the gaps between the porous solid particle mixture agglomerates, and the alkali metal salt particles or alkaline earth metal salt particles, which are electrolyte salts, dissolve in water, whereby an electrolyte salt layer is quickly formed. Since the alkali metal salt particles or alkaline earth metal salt particles, which are electrolyte salts, are present in a large amount, the electrolyte salt in such an electrolyte salt layer becomes supersaturated, saturated or nearly saturated, and contributes to potential stabilization. Note that quaternary ammonium salt particles can be used as the electrolyte salt particles.

  The porous solid particle mixture mass is a mixture mass having a structure that can be obtained by removing the dispersant from the solid particle mixture dispersed in the dispersant by heating, drying, or the like, and the porous gap is dispersed. It corresponds to the part where the agent was present. However, as long as it has the same porous structure, it is not limited to a method for producing a porous solid particle mixture mass. Also, some dispersant may remain.

  Since the solid particle mixture in the electrolyte salt-containing electrode layer of this embodiment is not hydrogel-dispersed, it is possible to avoid a potential change due to the volatilization of the electrode due to the evaporation of water during storage.

(I)
The preferred volume average particle size of the Ag particles constituting the electrolyte salt-containing electrode layer is 0.01 to 100 μm, and more preferably 0.1 to 50 μm. Similarly, the preferable volume average particle diameter of the particles of the specific alkali metal salt or alkaline earth metal salt constituting the electrolyte salt-containing electrode layer is 0.01 to 100 μm, more preferably 0.1 to 50 μm.

The electrolyte salt-containing electrode layer, in view of the potential stabilization, preferably contain more AgX _C salt particles, wherein the X _C ^{- ions, Cl -, Br -, I} - and SCN ^- from Selected from the group consisting of: The preferred volume average particle size of the AgX _C salt particles is 0.01 to 100 μm, more preferably 0.1 to 50 μm.

  The content weight ratio of the specific alkali metal salt and alkaline earth metal salt to Ag is preferably 0.01 or more and 10 or less, and more preferably 0.1 or more and 5 or less from the viewpoint of exhibiting a potential stabilizing effect by adding an electrolyte salt. More preferably, there is.

When an AgX _C salt is contained, the content ratio by weight to the total amount of AgX _C and Ag is preferably 0.01 or more and 10 or less from the viewpoint of exhibiting a potential stabilizing effect by adding an electrolyte salt. More preferably, it is 1 or more and 5 or less.

Even when the AgX _C salt is not blended, during the electrode reaction, the AgX _B salt or the AgX _C salt is formed from Ag and the X _B ^- ion of the specific alkali metal salt or the X _C ^- ion of the alkaline earth metal salt. It is thought to have occurred.

(C)
The electrode layer may include a supporting electrode layer covering the insulating support substrate in addition to the electrolyte salt-containing electrode layer. In this case, the electrolyte salt-containing electrode layer is formed on the supporting electrode layer.

Examples of the material of the supporting electrode layer include C (carbon), Ag (silver), a mixture of C (carbon) and Ag (silver), a mixture of Ag and AgX _D salt, and a mixture of C (carbon), Ag and AgX. One selected from the group consisting of mixtures with _D salts can be mentioned. Here, X _D ^{- ions, Cl -, Br -, I} - is selected from the group consisting of ^- and SCN.

(D)
Regarding the method for preparing the electrolyte salt-containing electrode layer, for example, a mixture of Ag particles, specific alkali metal salt particles or alkaline earth metal salt particles, and optional AgX _C salt particles is dispersed in a dispersant to form a mixture on an insulating support substrate. Alternatively, when the support electrode layer is present, the support electrode layer can be prepared by applying the support electrode layer using a printing method or the like (see the third embodiment of the present invention).

  Alternatively, as an alternative, a component excluding the specific alkali metal salt and alkaline earth metal salt particles is dispersed in a dispersant, and the insulating support substrate or, if a support electrode layer is present, the support electrode layer. After forming a film by coating using a printing method or the like, there may be a method of adding and drying an aqueous solution of alkali metal salt or alkaline earth metal salt particles on the film (see the fourth embodiment of the present invention). .

(A-2) Taste detection membrane (A)
A taste detection membrane is a lipid membrane capable of causing a change in potential difference (membrane potential) between the inside and the outside of the membrane by adsorption (electrostatic interaction or hydrophobic interaction) with various taste substances. It is. The surface of the human tongue is composed of a lipid membrane, and the taste detection membrane is an artificial lipid membrane capable of quantifying the taste by generating a potential difference similar to that of the lipid membrane of the tongue. Usually, such a taste detection membrane can be obtained by blending a lipid, a plasticizer, and a polymer (for example, polyvinyl chloride) to form a film (see Patent Documents 1 to 4).

  In the taste detection membrane, the type and sensitivity of the taste substance to be responded can be changed depending on the type of lipid to be added and the mixing ratio of the plasticizer. The human tongue is highly sensitive to bitterness because natural toxins often exhibit bitterness, and also sensitive to sourness (responds even at low concentrations) because spoiled foods exhibit sourness. On the other hand, it has low sensitivity to umami substances and salty taste, which is an essential component, which need to be ingested (there is no response unless the concentration is high). It is desired that a taste detection film corresponding to such characteristics of the human tongue is provided.

(I)
The taste detection film is embedded in the waterproof insulating layer, but has a surface to be measured, and is in electrical contact with the electrolyte salt-containing electrode layer. In other words, at least a part of the surface of the taste detection film is the contact surface of the test object exposed to the outside from the waterproof insulating layer, and the change in the membrane potential caused by the adsorption of the taste substance to the contact surface of the test object. Can be transmitted to the electrode layer.

(A-3) Waterproof insulating layer In the working electrode of this embodiment, a waterproof insulating layer is formed on the electrode layer. This layer has an insulating function and a waterproof function, which restricts fluid communication between the electrode layer, particularly the electrolyte salt-containing electrode layer and the external solution, and prevents the electrode surface from being in contact with the solution to be measured. It contributes to stabilization of X ^- ion concentration.

  As a suitable material for forming the waterproof insulating layer, any conventionally known waterproof material can be used. For example, an acrylic resin, an epoxy resin, or the like can be suitably used.

  An opening (film forming opening) for embedding the taste detecting film is formed in the waterproof insulating layer, and the taste detecting film is formed so as to fill the film forming opening.

(A-4) Insulating support substrate A substrate having a function of supporting an electrode layer, and any material commonly used in the art, for example, a polyethylene terephthalate film (PET) or glass can be used.

  A typical thickness is 50 to 2000 μm.

[B. Regarding the second embodiment of the present invention]
A second aspect of the present invention is a flat plate type taste sensor including the working electrode of the first aspect of the present invention and a reference electrode.

  FIG. 10 shows an example of a taste sensor having a plurality of electrodes on one substrate. For example, one of the electrodes can be used as a reference electrode, and the other electrode can be used as a working electrode of the present invention.

  As the reference electrode, any reference electrode that can be used for a plate-type electrode can be used, but, like the working electrode of the present invention, an electrode that can be manufactured by a printing method is more preferable. For example, the reference electrode of the first embodiment or the second embodiment described in Japanese Patent Application No. 2017-141281 can be exemplified.

[C. Regarding the third embodiment of the present invention]
A third aspect of the present invention is a method for producing a working electrode according to the first aspect of the present invention,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an electrolyte salt-containing electrode layer over the insulating support substrate,
(A) Ag particles;
(B) alkali metal salt particles or alkaline earth metal salt particles;
(C) after applying a mixture paste containing at least a dispersant, and heating and drying to form the electrolyte salt-containing electrode layer,
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) electrically contacting the electrolyte salt-containing electrode layer to form a taste detecting film having a surface for contacting an object to be measured so as to fill the opening for film formation. .

(C-1)
All of the step of forming the electrolyte salt-containing electrode layer (ii), the step of forming the waterproof insulating layer (iii), and the step of forming the taste sensing film (iv) can be easily performed by a printing method.

More specifically, in step (ii),
(A) Ag particles;
(B) alkali metal salt particles or alkaline earth metal salt particles;
(C) by applying a mixture paste containing at least a dispersant;
In step (iii), by applying a waterproof insulating layer material (for example, by applying and then curing a UV-curable acrylic resin);
In the step (iv), for example, a mixture of a lipid, a plasticizer (for example, dioctyl phthalate) and a polymer (for example, polyvinyl chloride) is melted using a solvent (such as THF) as necessary, Can be carried out by volatilizing.

(C-2)
In the production method of this embodiment, a dispersant is used to prepare a mixture paste for forming an electrolyte salt-containing electrode layer (electrolyte salt kneading method). One example of a dispersant is a water-soluble dispersant. The water-soluble dispersant is distinguished from a hydrogel dispersant (a dispersant using a gel having water as a medium), and is composed of a polymer of a polymer hydrogel (pHEMA) as described in Patent Document 3 and a chloride. Electrolyte layer composed of potassium). Examples of the water-soluble dispersant include polyethylene glycol and the like, and those having a viscosity and a surface-active action such that the electrolyte salt can be uniformly dispersed and mixed are preferable.

  In this embodiment, most of the dispersant is further removed by vaporization / decomposition by heating / drying. With respect to the removed portion, the portion where the dispersant was present becomes a void and becomes a porous solid particle mixture mass.

  Note that even if some dispersant remains, unlike the electrolyte layer composed of a polymer of a polymer hydrogel (pHEMA) and potassium chloride as described in Patent Document 3, due to the volatilization of water during storage, There is little risk of potential change due to the progress after the electrode is made.

Further, the mixture paste preferably further contains an AgX _C salt from the viewpoint of potential stability. Here, X _C ^{- ions, Cl -, Br -, I} - is selected from the group consisting of ^- and SCN.

  In addition, what can be generally used for the printing paste includes a main material, a solvent, a binder (binder), a viscosity modifier, a dispersant, and the like. The main material is a metal paste in the case of a conductive paste, and a resin or a metal oxide in the case of an insulating paste. The solvent is used to impart fluidity to the solid (powder, particle) main material so that it can be used for printing. Since an organic solvent is usually used, the paste is cured during drying (drying, firing, UV irradiation). Volatilized and decomposed, and hardly remains in the cured product. The binder (binder) is usually a resin or a low-melting glass, and remains in the cured product to some extent (or almost all) even after the paste is cured, and contributes to the binding between the main material particles (paste). Role). The viscosity modifier is an additive for adjusting the paste to have a viscosity suitable for each printing method (relatively hardened in screen printing, loosened in ink jet printing), and various compounds are used. Some remain after curing and some do not. The dispersant contributes to the stable and homogeneous dispersion of the components contained in the main material and other pastes without agglomeration or uneven distribution. There are various residuals after curing. In general, additives such as a binder, a viscosity modifier, and a dispersant are appropriately used, and are not included in all pastes.

The functions required of the dispersant in the present invention are, for example, as follows:
1. Aggregation of main particles such as silver, silver chloride and potassium chloride contained in the paste is suppressed, and the paste is stably and uniformly dispersed.
2. If the main material particles are homogeneously dispersed in the paste, good homogeneity can be obtained even after the solvent or the like volatilizes in the curing step. If the region is not homogeneously dispersed and, for example, there is a region where potassium chloride does not exist, an abnormal potential may be generated.
3. By volatilizing and decomposing during the curing step, voids are generated in the solid particle mixture mass (silver, silver chloride, potassium chloride), and a solid particle mixture mass having a certain degree of porosity is generated.

(C-3)
The film-forming opening of the waterproof insulating layer in the step (iii) may be formed by forming a waterproof insulating layer and then removing a predetermined region of the waterproof insulating layer.

  However, when the printing method is used in the step (iii), it is preferable from the viewpoint of efficient production to incorporate the film forming openings of the waterproof insulating layer in advance as a printing pattern.

(C-4)
When the working electrode includes a supporting electrode layer which is an arbitrary electrode layer, before the step (ii), for example, a supporting electrode layer material paste is applied on an insulating supporting substrate to form the supporting electrode layer, and then the step ( According to ii), the electrolyte salt-containing electrode layer can be formed on the support electrode layer.

(C-5)
The taste detection membrane is formed so as to be in electrical contact with the electrolyte salt-containing electrode layer and to fill the membrane formation opening.

  Since it is sufficient to make electrical contact with the electrolyte salt-containing electrode layer, it is not only physically secured, but also physically not directly in contact with the electrolyte salt-containing electrode layer. However, this includes the case where the electrodes are in electrical contact with each other via some kind of conductor.

  Forming so as to fill the film-forming opening means filling the film-forming opening so as not to impair the waterproofness of the waterproof insulating layer more than necessary.

(C-6)
In addition, A. Reference can be made to the description of the second aspect of the present invention.

[D. Regarding the fourth aspect of the present invention]
A fourth aspect of the present invention is a further method for producing a working electrode according to the second aspect of the present invention,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an Ag electrode layer over the insulating support substrate,
(A) Ag particles;
(B) applying a mixture paste containing a binder, followed by heating and drying to form the Ag electrode layer;
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) a step of adding a solution of an alkali metal salt or an alkaline earth metal salt to the Ag electrode layer portion in the film forming opening and drying the Ag electrode layer portion to form an electrolyte salt-containing electrode layer. So,
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(V) electrically contacting the electrolyte salt-containing electrode layer to form a taste detecting film having a surface for contacting an object to be measured so as to fill the opening for film formation. .

(D-1)
The method for producing a working electrode of this embodiment is different from the third embodiment in that a predetermined electrolyte salt is not previously contained in the mixture paste when the electrode layer is formed in the step (ii). After the formation of the layer and the waterproof insulating layer (steps (ii) and (iii)), a solution of the specific alkali metal salt or alkaline earth metal salt is applied to the Ag electrode layer portion in the film forming opening of the waterproof insulating layer. By adding and drying, at least a part of the Ag electrode layer is made into an electrolyte salt-containing electrode layer (step (iv)) (electrolyte salt solution dropping method).

  When a part of the Ag electrode layer is an electrolyte salt-containing electrode layer, the remaining Ag electrode layer becomes a support electrode layer (Ag support electrode layer).

  In this embodiment, most of the dispersant is removed from the electrode layer including the electrolyte salt-containing electrode layer by vaporization / decomposition by heating / drying. With respect to the removed portion, the portion where the dispersant was present becomes a void and becomes a porous solid particle mixture mass. Also, even if some dispersant remains, unlike an electrolyte layer composed of a polymer of a polymer hydrogel (pHEMA) and potassium chloride as described in Patent Document 3, the volatility of water during storage is There is little risk of potential change due to the progress after the electrode is made.

(D-2)
All of the step of forming the electrolyte salt-containing electrode layer (ii), the step of forming the waterproof insulating layer (iii), and the step of forming the taste detection film (v) can be easily performed by a printing method.

More specifically, in step (ii),
(A) Ag particles;
(B) by applying a mixture paste containing a dispersant;
Step (iii), by applying a waterproof insulating layer material (for example, by applying a curable acrylic resin, followed by curing);
In the step (v), for example, a mixture of a lipid, a plasticizer (eg, dioctyl phthalate) and a polymer (eg, polyvinyl chloride) is melted using a solvent (eg, THF) as necessary, Can be carried out by volatilizing.

(D-3)
In the manufacturing method of this embodiment, a dispersant is used to prepare a mixture paste for forming an Ag electrode layer, and after forming a waterproof insulating layer having a film forming opening, the Ag electrode layer in the film forming opening is formed. By adding and drying a solution (for example, an aqueous solution) of an alkali metal salt or an alkaline earth metal salt to the portion, the Ag electrode layer portion becomes an electrolyte salt-containing electrode layer.

The mixture paste may further contain AgX _C salt particles from the viewpoint of potential stability. Here, X _C ^{- ions, Cl -, Br -, I} - is selected from the group consisting of ^- and SCN.

(D-4)
The opening for forming a film of the waterproof insulating layer in the step (iii) may be manufactured by forming the waterproof insulating layer once and then removing a predetermined region of the waterproof insulating layer.

  However, when the printing method is used in the step (iii), it is preferable from the viewpoint of efficient production to incorporate the film forming openings of the waterproof insulating layer in advance as a printing pattern.

(D-5)
Before the formation of the Ag electrode layer in the step (ii), for example, a conductive material paste other than Ag is applied on the insulating support substrate, and between the insulating support substrate and the Ag electrode layer, as described in (D-1) above. A second support electrode that is distinct from the Ag support electrode layer may be provided.

(D-6)
In this embodiment, the electrolyte salt solution is dropped on the Ag electrode layer, so that a part of the Ag electrode layer is formed as the electrolyte salt-containing electrode layer. May be formed.

(D-7)
In addition, A. Reference can be made to the description of the first aspect of the present invention.

[Invention product 1 / Comparative product 1 production example]
(A)
Inventive product 1, which is the working electrode of the present invention, was produced by the following procedure (electrolyte salt kneading method) (see FIG. 2).

(I)
By printing a carbon paste (JELCON CH-8 carbon paste made by Jujo Chemical) on a substrate (glass, 1 mm thick) and drying it in an oven at 120 ° C. for 15 minutes, a support electrode layer (carbon conductive layer, film thickness of about 10 mm) was formed. 10 μm).

(Ii)
Next, an Ag particle / AgCl particle / KCl particle / polyethylene glycol (PEG) mixture paste was printed on a region of the surface of the obtained supporting electrode region including the region where the detection unit is to be formed, and the paste was heated at 220 ° C. in an oven at 18 ° C. By drying for a period of time, an Ag particle / AgCl particle mixture layer (electrolyte salt-containing electrode layer) containing KCl particles uniformly was formed. PEG in the used paste was almost removed by vaporization / decomposition by heating and drying in an oven (can be confirmed by a cross-sectional electron micrograph).

  Here, the Ag particle / AgCl particle / KCl particle / PEG mixture paste used was prepared by adding potassium chloride [Wako Pure Chemical Industries, Ltd.] to silver / silver chloride ink for reference electrode [011464, 7.7 g, manufactured by BAS Corporation]. A special grade reagent, 4.8 g as a pulverized product] and polyethylene glycol 600 [first grade, 3.8 g reagent, Wako Pure Chemical Industries, Ltd.] are added, and a kneading apparatus (Nawataro Naritaro AR-250) is present in the presence of 3 mm zirconia balls. , Manufactured by Shinky Co., Ltd.).

  In addition, the approximate particle diameter of each particle was about 0.01 to 2 μm for Ag particles, about 1 to 5 μm for AgCl particles, and about 1 to 50 μm for KCl particles as observed by a scanning electron microscope (SEM).

(Iii)
Next, the surface of the electrode layer (the supporting electrode layer and the electrolyte salt-containing electrode layer) using a UV-curable solder resist [acrylic resin, PLAS FINE PSR-310 (A-81) 250PS, manufactured by Ryo Chemical Industry Co., Ltd.]. A waterproof insulating layer was printed thereon and cured by UV irradiation (film thickness: 10 to 100 μm).

  In this printing, the printing pattern of the waterproof insulating layer was set so that an opening for (bitterness detection) film formation was formed on the electrolyte salt-containing electrode layer (see FIG. 2).

(Iv)
Then, about 7 μL of the lipid solution for bitterness detection was dropped into the opening for film formation and dried at room temperature for 2 days to form a film for taste detection.

  Here, the composition of the lipid solution for bitterness detection used was 400 mg of PVC (polyvinyl chloride), 300 mg of 2-nitrophenyloctyl ether (NPOE), 5 mg of tetradodecyl ammonium bromide (TDAB), and 4 ml of tetrahydrofuran (THF). Was.

(B)
A working electrode of Comparative Example 1 was prepared in the same manner except that an Ag / AgCl paste (011464 manufactured by BAS) was used in place of the mixture paste in the steps (i) to (iv) (FIG. 5).

  In addition, the “electrode layer (supporting electrode layer and electrolyte salt-containing electrode layer)” in the step (iii) is described as “an electrode layer”, and “an opening for film formation is formed on the electrolyte salt-containing electrode layer”. "Set the print pattern of the waterproof insulating layer (see FIG. 2)" means "set the print pattern of the waterproof insulating layer so that the film forming opening is formed at the position corresponding to the invention 1" (FIG. 5). See)).

[Inventive product 2-4 / Comparative product 2 production example]
(A)
Inventive products 2 to 4 as working electrodes of the present invention were produced by the following procedure (electrolyte salt solution dropping method) (see FIG. 3).

(I)
An Ag electrode layer was formed by printing an Ag paste (SP-A6PL, manufactured by Shin Nippon Kakin Co., Ltd.) on a substrate (glass, 1 mm thick) and drying it in a 500 ° C. oven for 2 hours (film thickness: 10 to 100 μm). ).

(Ii)
Next, a waterproof insulating layer was printed on the surface of the Ag electrode layer using a UV-curable solder resist [acrylic resin, PLAS FINE PSR-310 (A-81) 250PS, manufactured by Ryo Chemical Industry Co., Ltd.] Cured by UV irradiation. (Film thickness 10 to 100 μm).

  At the time of this printing, a printing pattern of the waterproof insulating layer was set so that a (bitterness detection) film forming opening was formed at the position where the detection portion of the Ag electrode layer was to be formed (see FIG. 3).

(Iii)
Next, a predetermined electrolyte aqueous solution (Invention 2: KCl aqueous solution (concentration 500 mM); Invention 3: KBr aqueous solution (concentration 500 mM); Invention 4: KI aqueous solution (concentration 500 mM) are respectively dropped into the opening for film formation. The amount of the drop was about 5 μL, and the drying conditions were 90 ° C. and 30 minutes or more on a hot plate.

  By this step, the portion of the Ag electrode layer mixed with the electrolyte salt becomes the electrolyte salt-containing electrode layer, and the remaining portion becomes the support electrode layer.

(Iv)
Next, about 7 μL of a lipid solution for bitterness detection having the same composition as that used in the preparation of the invention product 1 was dropped into the opening for film formation and dried at room temperature for 2 days to form a film for taste detection.

(B)
A working electrode of Comparative Product 2 was prepared in the same manner except that Step (iii) was omitted from Steps (i) to (iv) of the procedure for preparing Invention Products 2 to 4 (see FIG. 5).

[Inventive product 5 / Comparative product 3 production example]
(A)
Except that the electrolyte salt solution in the step (iii) is an aqueous KSCN solution (concentration: 500 mM), the same as the steps (i) to (iv) in the above [Inventive product 2-4 / Comparative product 2 preparation example] (A) The working electrode of Invention 5 was produced.

(B)
A working electrode of Comparative Product 3 was produced in the same manner as in [Inventive Product 2 to 4 / Comparative Product 2 Production Example] (B).

  Note that the comparative product 3 has the same composition as the comparative product 2, but was produced on the same day as the inventive product 5 for comparison with the inventive product 5.

[Examples of making comparative products 4 to 5]
(A)
A working electrode of Comparative Example 4 was produced by the following procedure (electrolyte salt solution dropping method) (see FIG. 4).

(I)
A carbon electrode layer was formed by printing a carbon paste (JELCON CH-8 carbon paste manufactured by Jujo Chemical) on a substrate (glass, 1 mm thick) and drying it in an oven at 120 ° C. for 15 minutes (film thickness of about 10 μm). ).

(Ii)
Next, a waterproof insulating layer is printed on the surface of the carbon electrode layer by using a UV-curable solder resist [acrylic resin, PLAS FINE PSR-310 (A-81) 250PS, manufactured by Ryo Chemical Industry Co., Ltd.] It was cured by UV irradiation (film thickness 10 to 100 μm).

  At the time of this printing, a printing pattern of the waterproof insulating layer was set so that an opening for (bitterness detection) film formation was formed at a position where the detection portion of the carbon electrode layer was to be formed (see FIG. 4).

(Iii)
Next, a predetermined electrolyte salt aqueous solution [KCl aqueous solution (concentration: 500 mM)] was dropped into the film forming opening and dried. Here, the drop amount was about 5 μL, and the drying conditions were 90 ° C. for 30 minutes or more on a hot plate.

  By this step, the portion of the carbon electrode layer mixed with the electrolyte salt becomes the electrolyte salt-containing electrode layer, and the remaining portion becomes the support electrode layer.

(Iv)
Next, a lipid solution for bitterness detection having the same composition as that used in the production of the invention product 1 was dropped into the opening for film formation, and dried at room temperature for 2 days to form a film for taste detection.

(B)
A working electrode of the comparative product 5 was prepared in the same manner except that the step (iii) was omitted from the steps (i) to (iv) of the procedure for preparing the comparative product 4 (see FIG. 5).

[Product of invention 6 / comparative product 6]
(A)
In the manufacturing steps (i) to (iv) of the invention product 1 (refer to the above [Invention product 1 / comparative product 1 preparation example] (A)), the “lipid solution for bitterness detection” in the process (iv) is replaced with “astringency”. A working electrode of Invention 6 was prepared in the same manner except that the term "detection lipid solution" was read (see FIG. 2).

  Here, the composition of the lipid solution for bitterness detection used was 400 mg of polyvinyl chloride (PVC), 300 mg of dioctylphenylphosphonate (DOPP), 50 mg of tetradodecyl ammonium bromide (TDAB), and 4 ml of tetrahydrofuran (THF).

(B)
In the manufacturing steps (i) to (iv) (refer to the [Invention product 1 / Comparative product 1 preparation example] (A)) of the invention product 1, Ag is used instead of the mixture paste of the invention product 1 in the step (ii). / AgCl paste (011464 manufactured by BAS Co., Ltd.) and converting the “lipid solution for bitterness detection” of step (iv) into a “lipid solution for astringency detection” having the same composition as that used in the preparation of the invention product 6 A working electrode of Comparative Example 6 was produced in the same manner except that the reading was replaced (see FIG. 5).

  In addition, the “electrode layer (supporting electrode layer and electrolyte salt-containing electrode layer)” in the step (iii) is described as “an electrode layer”, and “an opening for film formation is formed on the electrolyte salt-containing electrode layer”. "Set the print pattern of the waterproof insulating layer (see FIG. 2)" means "set the print pattern of the waterproof insulating layer so that the film forming opening is formed at the position corresponding to the invention 1" (FIG. 5). See)).

[Test Example 1]
It is a test example in which the variation of the potential response amount between similar products in bitterness measurement was examined.

  For each of Invention Products 1 to 5 and Comparative Products 1 to 5 having a bitterness detecting membrane, 19 working electrodes were prepared (total: 19 × 10 = 190), and 30 mM was used as an external solution (solution to be measured). Using an aqueous solution containing KCl and 0.3 mM L (+) tartaric acid, the potential response was measured.

  In addition, each of the 19 working electrodes was simultaneously formed on the same substrate by printing, and was separately measured by changing wirings at the time of measurement.

  The potential response was measured using a commercially available Ag / AgCl glass electrode (RE-2B manufactured by EC Frontier) as a reference.

  Table 1 shows the results of the standard deviation obtained for each of the 19 potential responses obtained for each working electrode.

(Discussion)
(I)
Since the standard deviation σ change rate (%) of each of the invention products 1 to 5 is less than 100%, by including the electrolyte salt in the electrode material of the working electrode, the potential response amount between the same products can be reduced. It has been found that variations can be reduced.

  As for the electrolyte salt, the variation in the case of using KCl was the smallest (invention products 1 and 2), but the variation in the potential response amount similarly decreased in other electrolyte salts (KBr, KI, KSCN). It turns out that there is a tendency.

Without being bound by theory, this is because Cl ⁻ is advantageous because of its close mobility to K ⁺ , but any electrolyte salt, like KCl, has a reversible equilibrium reaction with Ag as well as KCl. Is considered to be due to the formation of

(Ii)
Furthermore, the effect of the contained electrolyte salt referred to in the above (i) was observed when the electrode material was Ag / AgCl or Ag (Invention 1 vs. Comparative 1, Inventive 2 to 4 vs. Comparative 2, Inventive product 5 vs. comparative product 3), and was not recognized when the electrode material was carbon (C) (comparative product 4 vs. comparative product 5).

  Although this is not bound by theory, for example, taking KCl as an example of an electrolyte salt, the following electrode reaction at the working electrode:

May contribute to the reduction in the variation of the potential response amount.

  That is, the working electrode of the present invention contains an electrolyte salt such as KCl as a solid particle mixture state, and upon contact with the solution to be measured, a saturated electrolyte salt solution or an electrolyte solution very close to this is converted into a working electrode. It is thought that it occurs around the Ag particles that are the material. Since the saturation concentration is considered to be constant if the temperature is constant, it is considered that the variation in the potential response amount among products is correspondingly reduced.

  On the other hand, even in Comparative Example 4, although the working electrode contains KCl, the electrode reaction including the ionization of the electrode material itself as described above cannot be considered because the working electrode material is carbon (C). . On the contrary, in the comparative product 4, the variation of the potential response amount became large due to the presence of the electrolyte salt (the standard deviation σ change rate exceeded 100%). This is considered to be due to the fact that the reversible equilibrium reaction with an electrolyte salt such as KCl such as an Ag / AgCl electrode is not established.

(Iii)
The human tongue has a high sensitivity to bitterness, and therefore feels bitter even with a low potential response. For this reason, it is very advantageous for bitterness measurement to be able to suppress the variation of the potential response amount in bitterness measurement.

[Test Example 2]
It is a test example in which the variation of the potential response amount between similar products in astringency measurement was examined.

  For each of the invention product 6 and the comparative product 6 having the astringency detection membrane, 19 working electrodes were prepared (total: 19 × 2 = 38), and 30 mM KCl and 0 as an external solution (solution to be measured) were used. Using an aqueous solution containing 0.3 mM L (+) tartaric acid, the potential response was measured.

  In addition, each of the 19 working electrodes was simultaneously formed on the same substrate by printing, and was separately measured by changing wirings at the time of measurement.

  The potential response was measured using a commercially available Ag / AgCl glass electrode (RE-2B manufactured by EC Frontier) as a reference.

  Table 2 shows the results of the standard deviation obtained for each of the 19 potential responses obtained for each working electrode.

(Discussion)
Even in the astringency measurement, it is possible to reduce the variation of the potential response amount between the same products by including an electrolyte salt in the electrode material of the working electrode, although not as much as the bitterness measurement in Test Example 1. I understand what I can do.

  As shown in FIG. 8, there is a correlation between the concentration of lipid (tetradodecyl ammonium bromide (TDAB) in the membrane for bitter taste and the membrane for astringency) in the taste detection membrane and the variation of the potential response amount. The variation in the bitterness membrane (TDAB 5 mg) having a smaller amount of lipid is originally larger than that in the astringency membrane (TDAB 50 mg). For this reason, the effect of stabilizing the electrolyte salt appears more remarkably.

[Test Example 3]
It is a test example in which a change with time in a potential response amount after electrode preparation was measured.

  Seven working electrodes were prepared for Invention product 1 and Comparative product 1, respectively, and stored at room temperature and in a dark place from day 0 to day 135 from the date of electrode preparation, and as an external solution (solution to be measured) every predetermined number of days. , 30 mM KCl and an aqueous solution containing 0.3 mM L (+) tartaric acid, and the potential response was measured. However, since the calculation is performed excluding the measurement error and the like, the number of data varies from 5 to 7 data.

The potential response was measured using a commercially available Ag / AgCl glass electrode (RE-2B manufactured by EC Frontier) as a reference.
FIG. 6 shows the result.

(Discussion)
As is clear from FIG. 6, the working electrode of the invention product 1 containing the electrolyte salt KCl has a smaller change over time in the potential response after the electrode is produced, and is more stable than the comparative product 1 without the electrolyte salt. Potential response was given.

Although the stability is not limited by the theory, the effect of suppressing the change in the electrode surface state due to the lipid molecules in the taste detection membrane, that is, in the absence of an electrolyte salt such as KCl, the lipid quaternary Ammonium salts and other ions gradually permeate and diffuse into the porous Ag / AgCl electrode, which changes the environment around Ag / AgCl, whereas electrolyte ions such as KCl form Ag particles. It is considered that the presence of the compound in the vicinity of AgCl particles causes a saturated state of Cl ⁻ to be formed in advance in the vicinity of Ag / AgCl, thereby mitigating environmental changes due to lipid ions.

[Test Example 4]
It is a test example in which a variation in a potential response amount at various concentrations of a bitter substance (iso-α-acid) was examined.

  Prepare 10 working electrodes and 14 working electrodes of the invention product 1 and the comparative product 1, respectively, and use the solutions (30 mM KCl and 0.3 mM L (+) tartaric acid) containing various concentrations of bitter components as the external solution (the solution to be measured). Using an aqueous solution containing a predetermined concentration of iso-α-acid between 0 and 0.02% by volume), the potential was measured.

  Here, the volume% means a formula of {A / (A + B)} × 100, where A (mL) is the volume of the iso-α-acid used and B (mL) is the volume of the solvent (water) used. Means the numerical value obtained by

The potential was measured with a commercially available Ag / AgCl glass electrode (RE-2B manufactured by EC Frontier) as a reference.
The results are shown in Table 3, FIG. 7 and FIG.

(Discussion)
In the measurements of Test Examples 1 to 3, the concentration of the taste component (for example, a bitter component such as iso-α-acid) is measured at zero for the purpose of observing the variation of the basic electrode response (see FIG. 7). In this test example, it was confirmed that a test solution containing a bitter component can also obtain the effect of suppressing variation similarly. That is, the length of the error bar in each plot at each bitter component concentration is much shorter in the invention product 1 than in the comparison product 1 (see the error bars in FIGS. 7 and 8).

  Moreover, as is clear from FIG. 8, the invention product 1 maintains the same response amount as the comparison product 1 at various bitter substance concentrations.

[Test Example 5]
It is a test example in which the variation of the potential response at various concentrations of the lipid component [tetradodecyl ammonium bromide (TDAB)] in the taste detection membrane was examined.

  Prepare 14 working electrodes each of invention product 1 and comparative product 1, and use an aqueous solution containing 30 mM KCl and 0.3 mM L (+) tartaric acid as an external solution (a solution to be measured and a reference solution containing no bitter component). The potential response was measured for each.

The potential response was measured using a commercially available Ag / AgCl glass electrode (RE-2B manufactured by EC Frontier) as a reference.
FIG. 9 shows the result.

(Discussion)
As can be seen from FIG. 9, when the concentration of the lipid component (TDAB) (correlated to the amount of potential response) is low, the standard deviation of the invention product 1 is significantly smaller than the standard deviation of the comparison product 1. Was. In general, it is known that the bitterness detection membrane and the astringency detection membrane have a lower lipid concentration than the sourness detection membrane and the umami detection membrane, and the results in FIG. The technique has been shown to be particularly effective in membranes with low lipid concentrations, such as membranes for detection. That is, the variation (standard deviation), which becomes remarkable when the patented technology is not used especially when the lipid concentration of the membrane is low, can be suppressed by using the patented technology. In particular, the sensitivity of the human tongue is high, and the value of the detection threshold is low. It has been confirmed that the patented technology is advantageous for measuring bitter components.

DESCRIPTION OF SYMBOLS 1 Insulating support substrate 2 Support electrode layer 3 Electrolyte salt containing electrode layer 4 Electrode layer 5 Waterproof insulation layer 6 Taste detection membrane 7 Electrolyte salt layer AA '

Claims (11)

Covering the insulating support substrate,
(I) an electrode layer including an electrolyte salt-containing electrode layer;
(Ii) a laminate in which a waterproof insulating layer is laminated in this order;
A taste detection film embedded in the waterproof insulating layer, and a working electrode for a taste sensor comprising:
At least the electrolyte salt-containing electrode layer,
(A) Ag particles;
(B) a mixture with alkali metal salt particles or alkaline earth metal salt particles,
(A) and (b) are present as a porous solid particle mixture mass;
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- is selected from the group consisting of, ^- and SCN
A working electrode, wherein the taste detection membrane has a surface for contacting an object to be measured and is in electrical contact with the electrolyte salt-containing electrode layer. The electrolyte salt-containing electrode layer,
(C) containing an AgX _C salt,
X _C ^{- ions, Cl -, Br -, I} - and SCN ^-, characterized in that it is selected from the group consisting of a working electrode according to claim 1. The electrode layer covers the insulating support substrate, and further includes a support electrode layer,
The electrolyte salt-containing electrode layer is formed on the support electrode layer,
The supporting electrode layer is made of a conductive material such as C (carbon), Ag (silver), a mixture of C (carbon) and Ag (silver), a mixture of Ag and AgX _D salt, and a mixture of C (carbon), Ag and AgX. _D, comprising one selected from the group consisting of a mixture with a salt,
The working electrode according to claim 1, wherein the X _D ⁻ ion is selected from the group consisting of Cl ⁻ , Br ⁻ , I ⁻ and SCN ⁻ .   The working electrode according to any one of claims 1 to 3, wherein the alkali metal salt particles or alkaline earth metal salt particles include potassium chloride (KCl) particles.   The working electrode according to claim 1, wherein the taste detection film is a bitterness detection film or a bitterness detection film.   A flat plate type taste sensor comprising the working electrode according to any one of claims 1 to 5 and a reference electrode. A method for producing a working electrode for a taste sensor,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an electrolyte salt-containing electrode layer over the insulating support substrate,
(A) Ag particles;
(B) alkali metal salt particles or alkaline earth metal salt particles;
(C) after applying a mixture paste containing at least a dispersant, and heating and drying to form the electrolyte salt-containing electrode layer,
The alkali metal salt particles are represented as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion comprises Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) electrically contacting the electrolyte salt-containing electrode layer to form a taste detection film having a surface for contacting an object to be measured so as to fill the opening for film formation. The mixture paste further comprises:
(D) comprising an AgX _C salt,
X _C ^{- ions, Cl -, Br -, I} - and SCN ^-, characterized in that it is selected from the group consisting of The method of claim 7. The step (ii) comprises:
(Ii-1) a step of applying a conductive material-containing paste on the insulating support substrate to form a support electrode layer;
(Ii-2) forming the electrolyte salt-containing electrode layer by applying the mixture paste on the support electrode layer and then heating and drying the mixture paste;
The method according to claim 7, comprising: A method for producing a working electrode for a taste sensor,
(I) providing an insulating support substrate;
(Ii) forming an electrode layer including an Ag electrode layer over the insulating support substrate,
(A) Ag particles;
(B) applying a mixture paste containing a dispersant, followed by heating and drying to form the Ag electrode layer;
(Iii) a step of forming a waterproof insulating layer covering the electrode layer, provided that a film forming opening is provided in the waterproof insulating layer;
(Iv) a step of adding a solution of an alkali metal salt or an alkaline earth metal salt to the Ag electrode layer portion in the film forming opening and drying the Ag electrode layer portion to form an electrolyte salt-containing electrode layer. So,
The alkali metal salt particles are expressed as M _A ⁺ X _A ^- salt particles, wherein the M _A ⁺ ion is an alkali metal ion, and the X _A ^- ion is composed of Cl ⁻ , Br ⁻ , I ⁻ and SCN ^−. Selected from the group,
The alkaline earth metal salt ^{_{particles, M E 2+ (X B -}} ) is expressed as ₂ salt particles, M _E ²⁺ ions, an alkaline earth metal ion, X _B ^- ions, Cl ^-, Br ^-, I ^- and SCN ^- is selected from the group consisting of the steps,
(V) electrically contacting the electrolyte salt-containing electrode layer to form a taste detecting film having a surface for contacting an object to be measured so as to fill the opening for film formation. The mixture paste further comprises:
(C) containing an AgX _C salt,
X _C ^{- ions, Cl -, Br -, I} - and SCN ^-, characterized in that it is selected from the group consisting of The method of claim 10.

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