WO2017146247A1

WO2017146247A1 - Conductive material and method for producing same, and bioelectrode

Info

Publication number: WO2017146247A1
Application number: PCT/JP2017/007280
Authority: WO
Inventors: 鳥光　慶一
Original assignee: 国立大学法人東北大学
Priority date: 2016-02-28
Filing date: 2017-02-27
Publication date: 2017-08-31
Also published as: JP6587104B2; JP2017148452A

Abstract

[Problem] To provide a conductive material that has a conductive polymer adhered uniformly on the surface of a base material so as to achieve a lower resistance value. [Solution] Specifically, provided is a conductive material which is obtained by adhering, as a conductive polymer, PEDOT-pTS to a nylon base material or a base material chiefly consisting of silk or a silk-derived component. Also provided by the present invention are: a method for producing said conductive material, the method comprising (1) an adhesion step for adhering a pTS solution containing an oxidative component and p-toluenesulfonate (pTS) to a base material formed of silk fiber or nylon fiber or a base material coated with sericin or fibroin, and (2) a polymerization step for further adhering 3,4-ethylenedioxythiophene (EDOT) to said base material, to which the oxidative component and pTS have been adhered in the adhesion step, so as to cause a polymerization reaction for generating poly(3,4-ethylene-dioxythiophene)-p-toluenesulfonate (PEDDOT-pTS) to occur in the base material to create a state in which PEDDOT-pTS is adhered to said base material; and a bioelectrode that includes the conductive material.

Description

Conductive material, method for producing the same, and bioelectrode

The present invention relates to a conductive material, a manufacturing method thereof, and a biological electrode.

One of the active efforts in the field of medical engineering, which is a fusion field of medicine and engineering, is the creation of an alternative device for bodily functions. For this purpose, first, the potential of a living body must be accurately measured. Indispensable. Among the bioelectric potential measurements, for example, in the measurement of myoelectric potential, it is considered that not only the approach from the outside of the muscle but also the action of the muscle can be reproduced more accurately by measuring the electric potential from the inside. .

Therefore, it is flexible and can follow the movement of muscles, and can be used as an electrode for measuring electric potential from the inside of muscles. Coated conductive fibers have been developed by the present inventors (see, for example,

Patent Documents

1 and 2 or Non-Patent Document 1).

The conductive fibers described in Patent Document 1 and Non-Patent Document 1 use PEDOT-PSS (Poly (3,4-ethylenedioxythiophene) -polystyrenesulfonate) as a conductive polymer.
PEDOT-PSS adhering to the base fiber by dipping the base fiber in a conductive solution containing OT-PSS and running between the electrodes while pulling up the base fiber vertically from the conductive solution. Is produced by utilizing a so-called electrolytic polymerization method in which the polymer is electrochemically immobilized. Further, the conductive fiber described in Patent Document 2 uses PEDOT-PSS as a conductive polymer, and a resin composition obtained by mixing PEDOT-PSS and a binder resin is attached to a base fiber, followed by drying and heating. It is manufactured by solidifying or polymerizing by heating or the like.

Note that PEDOT-pTS (poly (3,4-ethylene-dioxythiophene) -p-toluenesulfonate) is known as a conductive polymer that is more conductive than PEDOT-PSS (see, for example, Non-Patent Document 2). ).

International Publication WO2013 / 073673 JP 2014-108134 A JP 2003-171874 A

Since the conductive fibers described in

Patent Documents

1 and 2 and Non-Patent Document 1 have a good touch, are excellent in durability and water resistance, and have flexibility, electrodes for measuring potential from the inside of the muscle, and the like Can be used as However, this conventional conductive fiber has a relatively high resistance value because PEDOT-PSS, which is a conductive polymer, is sparsely adhered to the surface of the base fiber, and noise is generated when it is used as an electrode. There was a problem of becoming larger.

The present invention has been made paying attention to such a problem. A conductive material having a conductive polymer uniformly attached to the surface of a base material and having a lower resistance value, a method for producing the same, and a biological electrode are provided. The purpose is to provide.

In order to achieve the above object, the conductive material according to the present invention has PEDOT-pTS attached to a substrate made of silk fiber or nylon fiber, or a substrate coated with sericin or fibroin. It is characterized by being. The adhesion to the substrate includes adhesion on the surface of the substrate, adhesion on the inside of the substrate, and both.

To summarize the materials of the base material, it is not limited as long as sericin or fibroin is contained, except for nylon fibers, even if it is silk that originally contains these proteins, Those added with these proteins may also be used.

Base materials for coating sericin or fibroin include polyamide fibers (including nylon fibers), polyester fibers, acrylic fibers, aramid fibers, polyurethane fibers, carbon fibers, etc .; plant materials such as cotton, hemp, jute In addition to the above-mentioned silk, animal fibers such as wool and collagen fibers; or mixed fibers thereof can be widely used. It may be a dyed fiber. Note that “covering” is an action of covering the surface of an object with a covering component in appearance, and its specific mode is not limited. For example, any form of “attachment”, “containing”, and “penetration” of the coating component to the object to be coated may be used.

Both sericin and fibroline can be obtained from silk (raw silk) by a known method, and are also commercially available. Sericin is a protein component that forms the outside of raw silk, and can be recovered from raw silk by, for example, the method disclosed in JP-A-11-131318, and is also commercially available (for example, stocks) Company plateau company). Fibroin is a protein component that forms the core of raw silk, and can be obtained, for example, by dissolving silk fiber with an alkaline solution and dialyzing it by the method disclosed in JP-A-6-70702, Commercially available (Silkgen G Solvel KE: Ichimaru Falcos Co., Ltd.). These sericin or fibroin can be produced basically by immersing the object to be coated (including yarn and fabric) in aqueous sericin or fibroin, drying, and washing to form a film. Yes (Patent Document 3). It is also possible to outsource such coating work to obtain a desired sericin coated substrate [for example, Art Co., Ltd. (Kiryu City, Gunma Prefecture): http://art-silk.jp/ ].

The above “silk fiber” means “silk or a fiber mainly composed thereof”. The silk fiber may be a single silk, but if necessary, a mixed fiber with other fibers can be used. Here, the “other fibers” include synthetic fibers, plant fibers, and animal fibers other than silk, which are exemplified as the objects to be coated with sericin or fibroin. In addition, silk is obtained from ordinary silkworm silk, wild silk thread, natural silk derived from silkworms and bees, and silk obtained using genetic recombination technology, such as silkworms obtained by incorporating a gene encoding a fluorescent protein. It is also possible to use “silk” or the like.

Nylon is a kind of “polyamide”, which is a polymer in which a large number of monomers are bonded by an amide bond, and generally includes an aliphatic skeleton, and is originally a name derived from a trademark of DuPont (USA). In this specification, the name “nylon” is used for the definition of the invention. Nylon 6 (monomer: ε-caprolactam), nylon 11 (monomer: undecane lactam), nylon 12 (monomer: lauryl lactam), nylon 66 (monomer: hexamethylenediamine) can be used as a base material in the present invention. And adipic acid), nylon 610 (monomer: hexamethylenediamine and sebacic acid), nylon 6T (monomer: hexamethylenediamine and terephthalic acid), nylon 6I (monomer: hexamethylenediamine and isophthalic acid), nylon 9T (monomer: nonanediamine) And terephthalic acid), nylon M5T (nonanediamine and terephthalic acid), nylon 612 (monomer: caprolactam and lauryl lactam), and the like. Other synthetic fibers such as Tetron are less likely to adhere to PEDOT-pTS even when subjected to the production method of the present invention, whereas in the case of nylon fibers, PEDOT-pTS is easily attached and reduced. Electrical resistance can be realized. A mixed fiber of nylon and other synthetic fibers can also be used as the substrate, but only nylon is preferred. Moreover, the fiber which combined nylon and silk fiber, and the fiber which coat | covered the above-mentioned nylon with sericin or fibroin are preferable as a base material.

The base material is preferably “linear” or “planar”. The linear shape means a thread-like, string-like, cloth-like or ribbon-like vascular bundle, etc., and the planar shape means a cloth-like, film-like, film-like, or sheet-like shape. . In addition to these “linear” or “planar”, for example, a “gel” base material can also be used. A typical example of the linear substrate is a yarn, and a typical example of the planar substrate is a woven fabric (plain weave, satin weave, etc.).

The electrical resistance value of the conductive portion of the conductive material according to the present invention is:
(A) When the substrate is a linear member, it is preferably 50 kΩ / cm or less, particularly preferably ²⁰ kΩ / cm or less at a cross-sectional area of about 2.5 × 10 ⁻⁴ cm ² .
(B) In cases other than (a) including the case where the substrate is a planar member, it is preferably 50 kΩ / cm or less, particularly preferably 20 kΩ / cm or less.

“The conductive portion” means a region of the base material where conductive treatment, specifically, PEDOT-pTS is attached. For example, when PEDOT-pTS is attached to only a part of the base material, the PEDOT-pTS attached region corresponds to the “conductive portion”.

About (a), as shown in the Example mentioned later, the electrical resistance value of the linear electroconductive material of this invention is a value which detected the electrical resistance value per linear length 1cm with the tester. The cross-sectional area of about 2.5 × 10 ⁻⁴ cm ² is the cross-sectional area of a standard thickness silk thread. “About” means that the number after the second decimal place of “2.5” is rounded off. Since the cross-sectional area is inversely proportional to the resistance value, the resistance value corresponding to the cross-sectional area can be easily calculated. If the cross-sectional area of the linear base material increases, the cross-sectional area of PEDOT-pTS is expected to increase accordingly, and it is easy to compare the conductive materials of the present invention with each other or with other conductive materials. This is a parameter of an appropriate electrical resistance value in the present invention. When the length of 1 cm cannot be secured, the electrical resistance value in the entire conductive region of the linear conductive material is measured, and the comparison is made by converting the electrical resistance value to the 1 cm length and the above cross-sectional area. Can do.

Regarding (b) above, when the shape of the substrate is other than a linear shape, typically in the case of a planar member such as a woven fabric, it cannot be determined simply by the cross-sectional area of the substrate. In addition, the total cross-sectional area of the conductive member is larger than the cross-sectional area of one linear member. Therefore, when the shape of the substrate is other than a linear shape, the electrical resistance value at a length of 1 cm in the conductive portion is obtained, and this is referred to as “the electrical resistance value per 1 cm (Ω or kΩ / cm)”. The preferred range and the optimum range of the linear member can be defined as the characteristics of the conductive material of the present invention.

As for the electrical resistance value of the 1 cm × 1 cm silk cloth of the example shown in FIG. 10 described later, the electrical resistance values of the 10 electrode elements produced were all less than 1.6 kΩ / cm. In addition, when the length of 1 cm cannot be ensured similarly to the linear base material, the electrical resistance value in the conductive region of the conductive material is measured, and the comparison is made by converting the electrical resistance value to a length of 1 cm. be able to.

The manufacturing method of the electroconductive material which concerns on this invention is a manufacturing method of an electroconductive material characterized by including the following process (1) and (2).
(1) An adhesion step in which a pTS solution containing an oxidizing component and pTS (p-toluenesulfonate) is adhered to a substrate made of silk fiber or nylon fiber, or a substrate coated with sericin or fibroin.
(2) EDOT (3,4-ethylenedioxythiophene) is further attached to the base material to which the oxidizing component and pTS are attached in the attaching step (1), and PEDOT-pTS (poly (3,4-ethylene) is attached to the base material. -Dioxythiophene) -p-toluenesulfonate) is allowed to proceed to form a PEDOT-pTS adhesion state on the substrate by proceeding with the polymerization reaction.

The adhesion of the oxidizing component and pTS in the adhesion step (1) is preferably performed by immersing the base material in the pTS solution, or by printing the pTS solution on the base material.

In the polymerization step (2), it is preferable to promote the polymerization reaction to PEDOT-pTS by attaching EDOT and heating. Further, after the polymerization step (2), it is preferable to further perform a step of washing and drying the substrate to which PEDOT-pTS is adhered. The washing means is preferably water washing, and in this case, it is more preferred to use distilled water or deionized water. Examples of the drying means include drying in a thermostatic bath, drying with hot air or warm air, drying with sunlight, etc., but drying in a thermostatic bath, drying with hot air or warm air is preferable. The drying temperature in the thermostatic bath is preferably 50 to 80 ° C., particularly preferably 60 to 70 ° C., and the surface temperature of the object by drying with hot air or hot air is also preferably 50 to 80 ° C., particularly preferably 60 to 70 ° C. It is.

PTS and EDOT are both available as commercial products.

According to the method for producing a conductive material according to the present invention, PEDOT-pTS, which is a conductive polymer superior in conductivity to PEDOT-PSS, is used as a base material compared to the case of using a conventional electrolytic polymerization method or the like. Can be uniformly adhered, and the electric resistance value of the conductive material can be significantly reduced. For this reason, it is possible to reduce noise when used as an electrode. The electrical resistance value of the conductive material manufactured by the conductive material manufacturing method according to the present invention is as described above.

In the conventional electropolymerization method or the like, PEDOT-pTS could hardly be adhered to the surface of the base material, and a conductive material could not be obtained, but by the method for producing a conductive material according to the present invention, PEDOT-pTS can be uniformly attached to the surface of the substrate. As described above, the method for producing a conductive material according to the present invention is suitable for producing the conductive material according to the present invention, and can produce a conductive material having excellent conductivity and a lower resistance value. it can.

Note that when PEDOT-PSS is used as the conductive polymer, the PEDOT-PSS cannot be uniformly and uniformly adhered to the substrate even if the conductive material manufacturing method according to the present invention is used. It is difficult to reduce the resistance value as compared with the conductive material manufactured by using the electrolytic polymerization method.

In the conductive material and the method for producing a conductive material according to the present invention, the base material is preferably subjected to enzyme refining (mainly by a proteolytic enzyme), acid refining or alkali refining.

In the method for producing a conductive material according to the present invention, the heating step is preferably performed at 50 to 100 ° C. for 10 minutes to 60 minutes, more preferably at 50 to 80 ° C. for 10 to 40 minutes, very preferably. Is 60 to 80 ° C. for 10 to 30 minutes. By this heating step, PEDOT-pTS can be more quickly and densely attached to the surface of the substrate, and the resistance value can be further reduced. In the method for producing a conductive material according to the present invention, the oxidation component is preferably a transition metal ion. Specifically, iron, cerium, or molybdenum ions, particularly ferric ions are preferably included. In this case, PEDOT-pTS can be generated efficiently.

The bioelectrode according to the present invention includes the conductive material according to the present invention.

The element of the biological electrode is a conductive material according to the present invention, and examples of the form of the element include a surface electrode and a puncture electrode.

The surface electrode punctures the action potential and brain wave transmitted by volume conduction from the skin, directly from the surface of muscles, brain, and other organs (hereinafter these surfaces are also referred to as “body tissue surfaces”). It is an electrode that is led out without accompanying, and is a biological electrode that is used by being attached to the muscle abdomen or head. This can also be used as a stimulation electrode for derivation of evoked potentials or treatment.

When the electrode of the present invention is a surface electrode, the contactable area of the electrode element with the body tissue surface is preferably 0.0004 to 100 cm ² , particularly preferably 0.0004 to 25 cm ^2. It is. Even if the contact area exceeds 25 cm ² , it can be used as a surface electrode. However, even if the contact area between the body tissue surface and the electrode element is significantly reduced, action potentials or evoked potentials, and brain waves The feature of the electrode of the present invention that “it can be derived well” is not fully utilized. If the contactable area is smaller than 0.0004 cm ² , it is difficult to sufficiently derive an action potential or an evoked potential, and an electroencephalogram. However, if the performance of the myoelectric measurement system or electroencephalogram measurement system is improved in the future, even if the contactable area is smaller than 0.0004 cm ² , there is a possibility that it can be used favorably as the surface electrode.

The “area that can be contacted with the body tissue surface” is an area that can contact the body tissue surface when a conductive material is used as the electrode element of the surface electrode. For example, the electrode element is planar. In this case, it is the area of the sheet surface. In the case of such a planar electrode element, 0.25 to 100 cm ² is particularly preferable, and 0.25 to 25 cm ² is more preferable. If the electrode element is linear, the area of the surface area of the linear electrode element that is expected to be in contact with the body surface (the area is, for example, the diameter of the linear material is one side and the contact with the body surface is expected) The length that can be approximated as a “rectangular area” with the other side as the other side) is the area that can come into contact with the body tissue surface. In the case of such a linear electrode element, 0.0004 to 0.02 cm ² is particularly preferable, and 0.0004 to 0.005 cm ² is more preferable. Even in the case of other shapes, it is an area that can actually come into contact with the surface of the body tissue and can be easily understood by those skilled in the art. The contactable area is a single electrode element. For example, in the case where a plurality of electrode elements are provided in a single surface electrode without contact with each other, the area of each electrode element.

The puncture electrode is an electrode that literally brings an electrode element into contact with the living body by puncturing to derive a desired biological signal, and includes a needle electrode and a wire electrode. This can also be used as a stimulation electrode for derivation of evoked potentials or treatment. Accessible surface area of the biological tissue of a living body electrode element of this embodiment is preferably a 0.0004 ~ 0.02 cm ^2, particularly preferably a 0.0004 ~ 0.002 cm ^2. This has a very small surface area as a puncture electrode as compared with the conventional case, but at the same time, an excellent bioelectrode function can be exhibited due to good conductive properties.

The conductive material according to the present invention can be suitably used as a bioelectrode because of its low resistance value, good touch, excellent durability and water resistance, and flexibility. In particular, since the base material uses a biomaterial such as silk or silk thread, it can be suitably used as a bioelectrode. The biomedical electrode according to the present invention can be used, for example, as an electrode for measuring an electric potential inside a muscle, an electrode for measuring an electrocardiogram, or the like. As shown in the examples described later, a multipoint electrode in which two or more electrode elements are arranged on one carrier (cloth or the like) is one of the preferred embodiments of the bioelectrode of the present invention.

According to the present invention, it is possible to provide a conductive material having a conductive polymer uniformly attached to the surface of a base material and having a lower resistance value, a method for producing the same, and a biological electrode.

4 is a chemical reaction formula showing a PEDOT-pTS production reaction in the method for producing a conductive material according to the embodiment of the present invention. It is a graph which shows the resistance value of each electroconductive material manufactured using the base material (silk thread) from which the refining method differs with the manufacturing method of the electroconductive material of embodiment of this invention. According to the method for producing a conductive material of the embodiment of the present invention, (a) raw silk, (b) soap smelting yarn, (c) soaping scouring yarn, (d) phosphoric acid smelting yarn, (e) enzyme smelting yarn are used. It is an electron micrograph of each electroconductive material manufactured in this way. It is a graph which shows the resistance value of the electroconductive material manufactured by the electroconductive material manufactured by the manufacturing method (chemical polymerization method) of the electroconductive material of embodiment of this invention, and the electrolytic polymerization method. (A) Conductive material manufactured using electrolytic polymerization method, (b) Electron micrograph of conductive material manufactured by the conductive material manufacturing method (chemical polymerization method) according to the embodiment of the present invention. is there. (A) Ordinary light observation when cultivating brain cells of chicken embryo on a cover glass, (b) Micrograph in fluorescence observation, (c) Used in the method for producing a conductive material of the embodiment of the present invention FIG. 5 is a micrograph of normal light observation and (d) fluorescence observation when culturing the brain cells of a chicken embryo on a cover glass coated with PEDOT-pTS. It is the (a) schematic diagram of the measurement condition which shows the electric potential measurement inside the muscle of a chicken embryo using the electroconductive material of embodiment of this invention, (b) It is a graph of the measurement result of the electric potential inside a muscle. It is drawing which shows the result of having examined the resistance value of the electroconductive material of this invention which used the sericin covering fabric as a base material. It is drawing which shows the result of having examined especially the washing | cleaning resistance in the electroconductive material of this invention which used the nylon fabric as a base material. (A) Schematic diagram of a multi-point surface electrode using the conductive material of the embodiment of the present invention, (b) Schematic diagram in which the multi-point surface electrode is worn by a subject, (c) Actual movement on the skin surface It is a graph of the measurement result of an accompanying electric potential. (A) Schematic diagram of a multipoint surface electrode for electroencephalogram measurement using the conductive material of the embodiment of the present invention, (b) Schematic diagram of mounting the multipoint surface electrode on the surface of a chicken embryo brain, (c) It is a graph of the measurement result of the electroencephalogram potential in the actual brain surface.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a conductive material and a method for manufacturing the conductive material according to the embodiment of the present invention.

The conductive material of the embodiment of the present invention has PEDOT-pTS attached to the base material, and is manufactured by the conductive material manufacturing method of the first or second embodiment of the present invention described below. .

That is, in the method for producing a conductive material according to the first embodiment of the present invention, first, (1) an oxidizing component and pTS as a dopant are dissolved in an organic solvent solution, and the base is based on the organic solvent solution. Dip the silk or silk of the material.

An organic solvent that can be a solvent for pTS is capable of dissolving pTS, an oxidizing component, and the like, and preferably has good compatibility with an aqueous solvent. Specific examples include monovalent lower alcohols having 1 to 6 carbon atoms, such as methanol, ethanol, propyl alcohol, isopropyl alcohol, butanol, pentanol, or hexanol. The skeleton of carbon atoms constituting these monovalent lower alcohols may be linear, branched or cyclic, and may be a combination of two or more. Moreover, you may dilute and use with water suitably. Among these, monovalent lower alcohols having 1 to 4 carbon atoms, specifically, methanol, ethanol, propyl alcohol, isopropyl alcohol, or butanol are suitable as the organic solvent for the pTS solution.

The oxidizing component contained in the pTS solution is not particularly limited as long as it can activate the polymerization reaction to PEDOT-pTS when pTS and EDOT are brought into contact, and examples thereof include transition elements and halogens. .

Transition elements include first transition elements such as iron, titanium, chromium, manganese, cobalt, nickel, and zinc; second transition elements such as molybdenum, silver, zirconium, and cadmium; third transition elements such as cerium, platinum, and gold Is exemplified. Among these, it is preferable to use a first transition element such as iron or zinc.

The content of the oxidizing component in the pTS solution varies depending on the type of the oxidizing component used, and is not particularly limited as long as it is an amount that can activate the above polymerization reaction. For example, in the case of ferric ion (Fe ³⁺ ) used in the examples of the present specification, 1 to 10% by mass is preferable as ferric chloride with respect to the pTS solution, and more preferably 3%. -7% by mass. If the amount is too large, the polymerization reaction proceeds rapidly, but it is difficult to remove iron in the subsequent step. If the amount is too small, the polymerization reaction proceeds slowly.

The content of pTS acting as a dopant in the pTS solution is preferably 0.1 to 10% by mass, more preferably 0.15 to 7% by mass, and particularly preferably 1 to 6% by mass with respect to the solution. %, Most preferably 2-5% by weight.

Next, (2) after adding the monomer EDOT to the solution, it is 50 to 100 ° C., preferably 10 to 60 minutes, more preferably 50 to 80 ° C. for 10 to 40 minutes, very preferably 60 to Heat at 80 ° C. for 10-30 minutes. After heating, the substrate is taken out of the solution, preferably washed with water, more preferably distilled water or deionized water, and then dried in a thermostatic bath, hot air or warm air, sunlight, or the like. EDOT is liquid and water-soluble at room temperature, and can be appropriately diluted with an aqueous solvent such as water.

The use ratio of the above-mentioned pTS solution to EDOT is pTS solution: EDOT = 10: 1 to 100: 1, preferably 20: 1 to 40: 1 in volume ratio.

In the method for producing a conductive material according to the second embodiment of the present invention, first, (1) an oxidizing component and pTS as a dopant are dissolved in an organic solvent solution, and the organic solvent solution is used as a base. Print on the material.

The oxidizing component contained in the pTS solution is not particularly limited as long as it can activate the polymerization reaction to PEDOT-pTS when pTS and EDOT are brought into contact. Examples include transition element ions and halogens. Is done.

Adhesion of the pTS-EDOT mixed liquid to the base material and the finished conductive material used in the pTS solution and / or EDOT used in the first and second embodiments of the present invention As long as the effects of the present invention are not impaired quantitatively or qualitatively, such as not impairing the electrical conductivity, other components can be blended as necessary.

For example, glycerin, polyethylene glycol-polyprene glycol polymer, ethylene glycol, sorbitol, sphingosine, phosphatidylcholine and the like, preferably glycerol, polyethylene glycol-polyprene glycol polymer, sorbitol and the like. By blending these components, the wettability characteristics of the conductive material can be adjusted and flexibility can be imparted, thereby improving the affinity with biological tissue, particularly skin, when used as a biological electrode. . In addition, surfactants, binders, natural polysaccharides, thickeners such as CMC (carboxymethylcellulose), and emulsion stabilizers are exemplified as other components.

FIG. 1 shows a PEDOT-pTS production reaction by the conductive material manufacturing method according to the first and second embodiments of the present invention. In addition, although the base material uses silk or silk thread, it is not limited to these. Further, as described above, Fe ³⁺ as an oxidizing component is an example, and the present invention is not limited to this.

Thus, the conductive material of the present invention can be suitably manufactured by the manufacturing method of the present invention. In the method for producing a conductive material according to the embodiment of the present invention, the PEDOT-pTS production reaction can be accelerated by the heating step, and the polymerization of PEDOT-pTS onto the substrate can be accelerated. In addition, by immersing an arbitrary range of a substrate in a solution or applying it by printing or the like in an organic solvent-based solution or printing process, the conductive range is formed in an arbitrary shape. Can do. Thereby, the electroconductive material which has the shape in which the range which has electroconductivity was suitable for a use or use environment can be manufactured.

In addition, according to the method for manufacturing a conductive material of the embodiment of the present invention, PEDOT-pTS, which is a conductive polymer, is evenly uneven on the surface of the substrate as compared with the case of using a conventional electrolytic polymerization method or the like. It can be made to adhere, and a resistance value can be reduced. Moreover, it is less time-consuming than using a conventional electrolytic polymerization method or the like, and the conductive material can be easily manufactured. This ease, which is the merit of the method for producing a conductive material (chemical polymerization method) according to the embodiment of the present invention, is a fiber or a substrate made of this material by a technique that cannot be realized by an electrolytic polymerization method such as printing or spraying. The conductivity can be realized.

The conductive material according to the embodiment of the present invention has a good touch, excellent durability and water resistance, flexibility, low resistance value, and high biocompatibility. It can be used as an electrode for measuring potential from the inside of a muscle or the skin surface, an electrode for measuring an electrocardiogram, an electrode for measuring an electroencephalogram, a biological electrode for clinical treatment, and the like.

Hereinafter, tests were conducted on the resistance value, biocompatibility, and the like of the conductive material according to the embodiment of the present invention, and evaluation and examination were performed based on the results.

[Examination of base material]
A silk thread (silk thread) was used as a base material, and a test was conducted as to whether or not the resistance value of the conductive material changed due to a difference in the refining method of the silk thread. In the test, 168 denier silk thread (cross-sectional area: about 2.5 × 10 ⁻⁴ cm ² ) was used with 8 pieces in 21 pieces. Silk yarn used for the test is raw silk (unrefined: the same applies below), phosphoric acid refined yarn (acid refined), soaping refined yarn (soap refined), soap refined yarn (alkali refined), enzyme refined yarn (proteolytic enzyme) Refining).

Five types of silk thread were used, and the conductive material was manufactured by the method for manufacturing the conductive material according to the embodiment of the present invention described below. Specifically, first, a butanol solution containing iron (III) ions of transition metal and pTS (“CLEVIOS CB 40 V2” manufactured by Heraeus Co., Ltd .: about 4% by mass as iron (III) p-toluenesulfonate). 6.3 ml of “CLEVIOS” is a registered trademark), and silk thread was immersed therein. Next, 220 μl of EDOT (“CLEVIOS MV2” manufactured by Heraeus, about 98.5% by mass, “CLEVIOS” is a registered trademark) is added to the solution, and then at 50 to 100 ° C. for 10 minutes to 60 minutes. Heating was performed in a thermostatic bath for minutes. After heating, the silk thread was taken out from the solution, washed with deionized water three times, and then dried in a constant temperature bath at 70 ° C. Of the above condition range, the conductive material prepared under the heating condition of 70 ° C. for 20 minutes was used in the following tests for each refining method.

The resistance value of the conductive material manufactured using each silk thread was measured, and the result is shown in FIG. As shown in FIG. 2, it was confirmed that the conductive material manufactured with the enzyme smelting yarn had the lowest resistance value, and the conductive material manufactured with the phosphoric acid smelting yarn also had the low resistance value. The electrical resistance value is a value obtained by measuring the electrical resistance value of 1 cm length of each yarn by a tester (the same applies hereinafter).

FIG. 3 shows electron micrographs of the surface of each of the above-mentioned silk threads with different refining methods. As shown in FIG. 3, it can be seen that the surface of the enzyme refined yarn is the smoothest and the surface of the phosphate refined yarn is also relatively smooth. From this, it is considered that the good surface condition of the enzyme refined yarn and the phosphate refined yarn is one of the causes of the low resistance value of the conductive material. That is, by producing a conductive material using a base material having a smooth surface such as an enzyme refined yarn or an acid refined yarn, PEDOT-pTS adheres tightly to the surface of the substrate and reduces the resistance value. it is conceivable that.

[Production method]
The following is one example, and the present invention is not limited to this.

The conductive material manufactured by the method for manufacturing the conductive material according to the embodiment of the present invention (hereinafter referred to as “chemical polymerization method”) disclosed in the above-mentioned “examination of the substrate”, and Patent Document 1 In addition, the conductive materials manufactured by using the electrolytic polymerization method described in Non-Patent Document 1 were compared. In both the conductive materials, the raw silk used in the above “examination of the base material” was used as the base material.

The conductive material produced by the electrolytic polymerization method was produced by the methods described in Patent Document 1 and Non-Patent Document 1. Specifically, first, the raw silk of the base material was immersed overnight in a mixed solution obtained by adding EDOT at a mass ratio of 0.1% to the PEDOT-PSS solution. Next, the Ag / AgCl electrode of the reference electrode and the Pt electrode of the counter electrode were immersed in the mixed solution, and both ends of the raw silk were sandwiched by clips connected to the working electrode while the central portion of the raw silk was immersed in the mixed solution. . Using a potentiostat, a polymerization potential (0.8 V vs. Ag / AgCl) was applied from both ends of the raw silk, and electrolytic polymerization was performed until the total charge reached 76.8 μC. Thereafter, the raw silk was pulled up from the mixed solution and dried in a constant temperature bath at 70 ° C.

As the conductive material manufactured by the chemical polymerization method, the one manufactured by performing the heating condition at 70 ° C. for 20 minutes in the above “examination of the base material” was used.

The resistance values of the conductive material produced by the above chemical polymerization method and the conductive material produced by the electrolytic polymerization method were measured, and the results are shown in FIG. As shown in FIG. 4, it was confirmed that the resistance value of the conductive material manufactured by the chemical polymerization method is about 4 digits lower than that of the conductive material manufactured by the electrolytic polymerization method. Thus, since the conductive material manufactured by the chemical polymerization method has excellent conductivity and lower resistance value, noise can be reduced when this is used as an electrode, and more accurate measurement is performed. be able to.

FIG. 5 shows electron micrographs of the conductive material produced by the chemical polymerization method and the conductive material produced by the electrolytic polymerization method. As shown in FIG. 5 (a), in the conductive material manufactured by the electrolytic polymerization method, PEDOT-PSS adheres to a part of the surface of the substrate, whereas as shown in FIG. 5 (b). In addition, it was confirmed that PEDOT-pTS was uniformly and uniformly attached to the entire surface of the base material in the conductive material produced by the chemical polymerization method. In general, the larger the surface area of PEDOT covering the surface of the base material, the higher the conductivity and the lower the resistance value. Therefore, the difference in the adhesion method of PEDOT shown in FIG. It is considered a thing.

[Examination of biocompatibility]
A test for examining the biocompatibility of the conductive material according to the embodiment of the present invention was performed. First, PEDOT-pTS was dropped on the surface of the cover glass and spin-coated to prepare a thin film of PEDOT-pTS, on which primary culture of chicken embryo brain cells was performed. In culture, chicken embryo brain was first immersed in trypsin solution for about 10 minutes and pipetted about 10 times, then 300 μl was transferred to a 35 mm culture dish, 2% B27 supplement, 0.074 mg / ml L-glutamine, 25 μM. 2 ml of a culture medium consisting of Neurobasal medium containing glutamate and 20 ng / ml NGF was added. This was placed in a 37 ° C. incubator and cultured for 24 hours. After completion of the culture, the cells were stained with the fluorescent dye acridine orange (5 μg / ml) and excited by an Ar laser to determine viability. If the cell is dead, the fluorescent dye is not excreted and fluorescence is observed. For comparison, culture and fluorescence observation were also performed for the case of only the cover glass without spin coating with PEDOT-pTS.

The results are shown in FIGS. 6 (a) to (d). 6 (a) and 6 (b) are photomicrographs of normal light observation and fluorescence observation when culturing the brain cells of a chicken embryo on a cover glass. FIGS. 6 (c) and (d) ) Shows normal light observation and fluorescence observation when culturing the brain cells of a chicken embryo on a cover glass coated with PEDOT-pTS used in the method for producing a conductive material according to the embodiment of the present invention. FIG. As shown in FIG. 6 (b), in the case where PEDOT-pTS was not spin-coated, a large amount of fluorescence was observed and there were many dead cells, whereas as shown in FIG. 6 (d), PEDOT- In the case where pTS was spin-coated, almost no fluorescence was observed, and it was confirmed that the cells were cultured alive. From this result, it can be seen that PEDOT-pTS has high biocompatibility and there is almost no rejection from living tissue.

Next, as shown in FIG. 7A, in the conductive material according to the embodiment of the present invention in which PEDOT-pTS is attached to the surface of the silk thread of the base material (in the above “examination of the base material”, 70 ° C. In addition, the potential inside the muscles of chicken embryos was measured using a 20-minute heating condition performed on raw silk as a bioelectrode element. The measurement result is shown in FIG. As shown in FIG. 7B, it was confirmed that when a muscle was exercised by applying a stimulus, it was possible to measure a potential change accompanying the exercise.

[Examination of sericin-coated fabric as a base material]
(1) Production of sericin-coated fabric The sericin-coated fabric was commissioned to Art Co., Ltd. (Kiryu City, Gunma Prefecture).
The fabric base materials are six-row double fabric (Ryoei Textile Co., Ltd.), nylon fabric (Toray Co., Ltd.), acetate fabric (acetylcellulose / Mitsubishi Rayon), polyester fabric, rayon fabric (cellulose / Asahi Kasei), Cupra fabric (cellulose, Asahi Kasei Bemberg).

(2) Adhesion process of PEDOT-pTS to sericin-coated fabric For each of the prepared sericin-coated fabrics (5 cm × 1 cm), a conductive material is produced by the following steps of the method for producing a conductive material of the present invention. did. Specifically, first, a butanol solution containing iron (III) ions of transition metal and pTS (“CLEVIOS CB 40 V2” manufactured by Heraeus Co., Ltd .: about 4% by mass as iron (III) p-toluenesulfonate). 10 ml of “CLEVIOS” is a registered trademark), and each sericin-coated fabric was immersed therein. Next, 310 μl of EDOT (“CLEVIOS MV2” manufactured by Heraeus Co., Ltd .: about 98.5% by mass of EDOT, “CLEVIOS” is a registered trademark) was added to the solution, and then in a thermostatic bath at 70 ° C. for 30 minutes. Heating was performed. After the heating, the sericin-coated fabric was taken out from the solution, washed with shaking with deionized water twice for about 1 hour, and then dried in a constant temperature bath at 70 ° C.

The resistance value of the conductive material manufactured as described above was measured with a potentiostat by clipping at intervals of 2 cm in width using a flat clip, and the resistance value per 1 cm length was calculated. The results are shown in FIG. 8 (the unit of resistance value on the vertical axis is “Ω / cm”). As shown in FIG. 8, various sericin-coated fabrics had a maximum value in the vicinity of 20 kΩ / cm, and the minimum value was in the vicinity of 5.2 kΩ / cm. Thereby, it became clear that a sericin covering fabric is suitable as a base material of the electroconductive material of this invention. In addition, it is considered that the resistance value of the sericin-coated fabric using the hexagonal double fabric (silk) is relatively high because the thickness of the fabric is much thinner than others.

[Examination of nylon as a base material]
In order to evaluate the washing resistance of PEDOT-pTS adhered fabric (all 5 cm × 1 cm) produced using a synthetic fabric as a base material, (1) nylon fabric (Toray Industries, Inc .: nylon 6, nylon 66, or However, it is unclear at the time of the verification of this example, but it is expected that substantially the same result can be obtained by using any of these types of nylon. .), (2) Acetate fabric (acetylcellulose / Mitsubishi Rayon), (3) Polyester fabric, and (4) Silk fabric (Double Satin), respectively, by the steps of the production method of the present invention shown below. Manufactured. Specifically, first, a butanol solution containing iron (III) ions of transition metal and pTS (“CLEVIOS CB 40 V2” manufactured by Heraeus Co., Ltd .: about 4% by mass as iron (III) p-toluenesulfonate). 10 ml of “CLEVIOS” is a registered trademark), and each fabric was immersed therein. Next, 310 μl of EDOT (“CLEVIOS MV2” manufactured by Heraeus Co., Ltd .: about 98.5% by mass of EDOT, “CLEVIOS” is a registered trademark) was added to the solution, and then in a thermostatic bath at 70 ° C. for 30 minutes. Heating was performed. After heating, the fabric was taken out of the solution (fabric before washing), and the resistance value was measured. Next, shaking washing with deionized water was performed twice for about 1 hour, and further dried in a constant temperature bath at 70 ° C. (cloth after washing), and the electric resistance value was measured.

The resistance values of the conductive material manufactured as described above before and after cleaning are measured with a potentiostat by clipping at a width of 2 cm using a flat clip, and the resistance per 1 cm length is measured. The value was calculated. The results are shown in FIG. 9 (the unit of resistance value on the vertical axis is “Ω / cm”). In FIG. 9, the left bar indicates “resistance value before washing”, and the right bar indicates “resistance value after washing” for each fabric. Only nylon fabric and silk cloth had lower resistance after washing than before washing. It was clear that silk fabrics showed the best washing resistance, but nylon fabrics also showed sufficient washing resistance for practical use.

[Examination of multi-point electrode for surface (1)]
The examination content of this surface myoelectric measurement is shown by the schematic diagram of FIG. 10 and the potential measurement chart.

A ribbon-like silk cloth having a width of 1 cm and a length of 10 cm (a plain weaved silk fabric made of a proteolytic enzyme refining enzyme) is used as a base material. The manufacturing method (chemical polymerization method) under the above heating conditions was applied to manufacture a conductive material, and the conductive material was further cut into 1 cm square (area 1 cm ² ) to manufacture 10 surface electrode elements of the size. When the electric resistance values between the ends of these ten flat plate-like conductive materials were measured with a tester, they were all less than 1.6 kΩ. In each of these surface electrode elements, a linear electrode element manufactured by performing heating conditions for 70 minutes at 70 ° C. for raw silk (unrefined) in the same “examination of substrate”, The unit element of the multipoint electrode for surface was created by connecting by sewing. It is even easier to pierce the linear part of the unit element with a sewing needle from the perpendicular direction to the silk fabric surface (a plain weave silk fabric made of proteolytic enzyme refining). Sewed. The area of the cloth surface was 10 cm square (area 100 cm ² ), and nine unit elements were sewn so as to be equidistant at intervals of 0.5 cm. Thus, the multipoint electrode for surfaces was produced (FIG. 10 (a)).

Next, the surface multipoint electrode is fixed in a state where the surface electrode element exposed side and the subject's arm are in contact with each other, and the change in potential due to the movement of the subject's hand is measured with a commercially available wireless muscle. Measurement was carried out using an electric meter (ID3PAD: manufactured by Osaka Electronics) (FIG. 10B). In the measurement, a substance for reducing impedance such as gel was not applied between the surface multipoint electrode and the skin, and the electrode was directly brought into contact with the skin.

[Examination of multi-point electrode for surface (2)]
The examination contents of the surface electroencephalogram measurement are shown by the schematic diagram of FIG. 11 and the potential measurement chart.

A manufacturing method (chemical polymerization method) for heating conditions of 70 ° C. for 20 minutes disclosed in the above “examination of base material” for silk yarn having a diameter of 0.2 mm (silk yarn subjected to enzyme refining with a proteolytic enzyme) The linear electrode element which uses the said silk thread as a base material was manufactured. A 20 mm square (area 400 mm ² ) silk cloth (a plain weave silk fabric made of proteolytic enzyme refining) is used as an insulator, and the linear electrode element is pierced from the vertical direction of the back surface. Further, the front end portion of the pierced linear electrode element is pierced again with respect to the cloth surface so that a line length of 1 mm is exposed on the cloth surface, and sewing is performed as the first linear electrode element. Then, the sewing was fixed in the same manner so as to be orthogonal to the 1 mm exposed portion of the first linear electrode element in the vicinity of the sewing fixing portion of the first linear electrode element. The two linear electrode elements sewn and fixed orthogonally in this way were used as a unit element of a set of multipoint electrodes for the surface. As described above, since there are two pieces of 1 mm of 0.2 mm-wide silk thread, the electrode area of the set is 0.004 cm ² . The unit element was sewed on the 20 mm square cloth surface so that each of the unit elements was equidistant at intervals of 5 mm. In this way, a multipoint electrode for the surface for electroencephalogram measurement was created (FIG. 11 (a)).

Next, the surface of the multipoint electrode for electroencephalogram measurement is brought into contact with the surface of the brain from which the skull of a chicken embryo (embryonic day 19) has been removed, thereby bringing the cranial nerve activity into a commercially available RZ5 bioamplifier. (TDT) was measured by wire connection (FIG. 11 (b)). In the measurement, a substance for reducing impedance was not applied between the multipoint electrode for surface and the skin, and the electrode was directly brought into contact with the brain.

Thus, it can be said that the conductive material of the embodiment of the present invention is excellent in biocompatibility and can be sufficiently used as a bioelectrode. In particular, when the base material is made of silk fiber, it can be suitably used as a bioelectrode.

Claims

PEDOT-pTS (poly (3,4-ethylene-dioxythiophene) -p-toluenesulfonate) is attached to a substrate made of silk fiber or nylon fiber, or a substrate coated with sericin or fibroin. A conductive material characterized by that.
The conductive material according to claim 1, wherein the base material is linear or planar.
The electrical resistance value of the conductive part is
(1) When the base material is a linear member, the cross-sectional area is about 2.5 × 10 −4 cm 2 and is 50 kΩ / cm or less,
(2) The conductive material according to claim 1 or 2, wherein the material is 50 kΩ / cm or less in cases other than (1) including the case where the substrate is a planar member.
A biological electrode comprising the conductive material according to any one of claims 1 to 3.
The biological electrode according to claim 4, wherein the biological electrode is a surface electrode, and an area of the planar electrode element that can contact the biological tissue is 0.25 to 100 cm 2. .
5. The biological electrode according to claim 4, wherein the biological electrode is a surface electrode, and the area of the linear electrode element that can be contacted with the biological tissue is 0.0004 to 0.002 cm 2 . Bioelectrode.
The biological electrode according to claim 4, wherein the biological electrode is a puncture electrode, and an area of the electrode element that can contact the biological tissue is 0.0004 to 0.002 cm 2 .
The biological electrode according to any one of claims 4 to 7, wherein the biological electrode is a multipoint electrode.
The manufacturing method of an electroconductive material characterized by including the following process (1) and (2).
(1) An attachment step of attaching a pTS solution containing an oxidizing component and pTS (p-toluenesulfonate) to a substrate made of silk fiber or nylon fiber, or a substrate coated with sericin or fibroin;
(2) EDOT (3,4-ethylenedioxythiophene) is further attached to the base material to which the oxidizing component and pTS are attached in the attaching step (1), and PEDOT-pTS (poly (3,4-ethylene) is attached to the base material. -Dioxythiophene) -p-toluenesulfonate) is allowed to proceed to form a PEDOT-pTS adhesion state on the substrate by proceeding with the polymerization reaction.
The attachment of the oxidizing component and pTS in the attaching step (1) is performed by immersing the base material in the pTS solution, or by printing the pTS solution on the base material. The method for producing a conductive material according to claim 9.
The method for producing a conductive material according to claim 9 or 10, wherein in the polymerization step (2), EDOT is adhered and heated to promote polymerization reaction to PEDOT-pTS.
The method for producing a conductive material according to claim 11, wherein the heating is performed at 50 to 100 ° C for 10 to 60 minutes.
The production of the conductive material according to any one of claims 9 to 12, further comprising a step of washing and drying the substrate to which PEDOT-pTS is adhered after the polymerization step (2). Method.
The method for producing a conductive material according to any one of claims 9 to 13, wherein the oxidizing component is ferric ion.