Deep eutectic liquid, biological electrode composition, biological electrode, and method for producing biological electrode

Abstract

The invention relates to a deep eutectic liquid, a biological electrode composition, a biological electrode, and a method for manufacturing the biological electrode. Provided are: a deep eutectic liquid which has high ionic conductivity and is safe even when in contact with a living body; a biological electrode composition containing the deep eutectic liquid; a biological electrode in which a biological contact layer is formed from the biological electrode composition; and a method for manufacturing the same. A deep eutectic liquid which is a mixture of a hydrogen-bond-donating compound and a hydrogen-bond-accepting compound, the hydrogen-bond-donating compound being a compound represented by general formula (1) and having a structure in which 2 to 100 monomers having hydroxyl groups are bonded. The hydrogen-bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by general formulae (2)-(6) or a quaternary phosphonium cation represented by general formula (7), and the deep eutectic liquid is present as a liquid at 25 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to a deep eutectic liquid, a biological electrode composition, a biological electrode, and a manufacturing method of a biological electrode. PRIOR ART

[0002] In recent years, with the spread of IoT (Internet of Things), development of wearable devices is advancing. A watch, glasses that can connect to the Internet are representative examples thereof. In addition, in the medical field, the sports field, a wearable device that can monitor the state of the body at all times is also required, and is a growth field in the future.

[0003] In the medical field, a wearable device that monitors the state of an organ of the body by sensing of a weak electric current, such as electrocardiogram measurement that senses the beat of the heart by an electric signal, is being studied. In the measurement of an electrocardiogram, an electrode coated with a conductive paste is worn on the body to perform the measurement, but this is a short-time measurement of only once. In contrast, the development of the above-mentioned wearable device for medical use is aimed at the development of a device that monitors the health condition at all times for several weeks. Therefore, for a biological electrode used in a wearable device for medical use, it is required that there be no change in conductivity, no skin allergy even in the case of long-term use. In addition to these, it is also required to be lightweight and capable of being manufactured at low cost.

[0004] As a wearable device for medical use, there are a type attached to the body and a type assembled to clothes, and as a type attached to the body, a biological electrode using a water-soluble gel containing water and an electrolyte as a material of the above-mentioned conductive paste has been proposed (Patent Literature 1). The water-soluble gel contains sodium, potassium, calcium as electrolytes in a water-soluble polymer for retaining water, and converts a change in ion concentration from the skin into electricity. On the other hand, as a type assembled to clothes, a method of assembling a conductive polymer such as PEDOT-PSS (Poly-3,4-ethylenedioxythiophene-Polystyrenesulfonate), a silver paste to a fiber to make a cloth for an electrode has been proposed (Patent Literature 2).

[0005] However, in the case of using the above-mentioned water-soluble gel containing water and an electrolyte, there is a problem that the conductivity disappears when water disappears due to drying. On the other hand, in the case of using a metal such as copper that has a high tendency to ionize, there is a problem that there is a risk of causing skin allergy depending on the person, and in the case of using a conductive polymer such as PEDOT-PSS, there is a problem that there is a risk of causing skin allergy due to the strong acidity of the conductive polymer, and the conductive polymer peels off from the fiber in washing.

[0006] In addition, since it has excellent electrical conductivity, the use of metal nanowires, carbon black, and carbon nanotubes, etc. as electrode materials has also been studied (Patent Documents 3, 4, 5). Since the probability of contact between the metal wires increases, current can be passed with a small amount of addition. However, since the metal wire is a fine material with a sharp tip at the front end, it becomes a cause of skin allergy. In addition, carbon nanotubes are also irritating to living organisms for the same reason. Carbon black, although it does not have the toxicity of carbon nanotubes, has some irritating effect on the skin. In this way, even if it does not cause an allergic reaction itself, there are cases where the biocompatibility becomes poor due to the shape and irritating effect of the material, and it is difficult to balance electrical conductivity and biocompatibility.

[0007] Since the metal film has very high electrical conductivity, it is considered to function as an excellent living body electrode, but this is not necessarily the case. Since the heartbeat releases not only a weak current but also sodium ions, potassium ions, and calcium ions from the skin. Therefore, it is necessary to convert the concentration change of the ions into a current, but noble metals, which are difficult to ionize, have a poor effect of converting the ions from the skin into a current. Therefore, the impedance of the living body electrode using a noble metal is high, and the current passing through the skin is high resistance.

[0008] It has been proposed that a lithium ion conductive composite for a solid electrolyte includes a silicon-containing compound having a lithium ion-containing segment. It is known that it has a good conductivity and a good lithium ion mobility at the use temperature of the battery, and has excellent mechanical properties, formability, and good adhesion to the electrode, reduced risk of fire, leakage, and other high safety of the battery (Patent Document 6).

[0009] It has been proposed to add a living body electrode with an ionic polymer added (Patent Documents 7, 8, 9, 10). A living body electrode obtained by adding an ionic polymer and carbon powder to a silicone adhesive and mixing has adhesion, and can collect biological signals even if it is attached to the skin for a long time. Since the ionic polymer does not penetrate the skin, it has no irritating effect on the skin, and has high biocompatibility.

[0010] Silicone is originally an insulator, but the ionic conductivity is improved by the combination of the ionic polymer and the carbon powder, and functions as a living body electrode. However, it is required to improve the performance by further improving the ionic conductivity.

[0011] Patent Documents 7, 8, 9, and 10 described above disclose that the addition of a silicone compound having a polyether chain is effective for improving ionic conductivity. The polyether chain is also used to improve the ionic conductivity of a lithium ion polymer battery, and is effective for improving the conductivity of ions. However, the ionic conductivity of a water-soluble gel is lower than that in a water-containing gel, and it is necessary to further improve the ionic conductivity.

[0012] A bioelectrode is required to acquire a signal immediately after being attached to the skin. A gel electrode can acquire a signal immediately after being attached to the skin because the ion concentration of the skin and the electrode is close, the ions move in and out smoothly, and the ions in the water-containing gel move at a high speed. On the other hand, a dry electrode takes a long time from being attached to the skin to acquiring a signal. It is considered that this is because a signal does not appear until the ions released from the skin are saturated on the surface of the dry electrode.

[0013] In addition, Patent Documents 7, 8, 9, and 10 disclose an ionomer alone or a composition in which a resin, a conductive particle, and a compound containing polyglycerol are combined as a bioelectrode. However, since the ionomer exists in a solid form under dry conditions, it is considered that it exists in a solid form in a dry electrolyte as well. Although such a material as a solid electrolyte is known, the ion conductivity of the ionomer shown in the aforementioned Patent Documents 7, 8, 9, and 10 is not confirmed. Also, in general, the ion conductivity of a liquid is higher than that of a solid, and thus it is considered that the ionomer locally present in a dry electrode is disadvantageous from the viewpoint of ion conductivity. Therefore, it is considered that the ion conductivity of the ionomer is poorer than that of the ions in the water-containing gel of the water-soluble gel.

[0014] On the other hand, a material such as a deep eutectic liquid obtained by mixing a hydrogen bond-donating compound and a hydrogen bond-accepting compound is known. As characteristics of the deep eutectic liquid, a liquid at room temperature, a low vapor pressure, not as volatile as water, flame retardancy, thermal stability, electrochemical stability, conductivity, low cost, environmental friendliness, low toxicity, and the like can be given. Since the deep eutectic liquid is a liquid, by being incorporated into a dry electrode, it is expected to reduce the ion conductivity and the surface resistance to the living body.

[0015] However, since various combinations exist in the deep eutectic liquid, when used for a dry electrode, it is necessary to be composed of a substance that is non-irritating to the skin and non-toxic. That is, the hydrogen bond-donating compound and the hydrogen bond-accepting compound need to be selected from materials having biocompatibility, respectively.

[0016] Patent Document 11 discloses a food containing a flavor composition using a deep eutectic liquid. In order to enter the human body, the food must be biocompatible and non-toxic. As examples of such a deep eutectic liquid, amino acids, sugars, and compounds generated in the body can be given, and it is considered that these compounds are not problematic even if applied to a dry electrode.

[0017] By incorporating such a biocompatible deep eutectic liquid into a dry electrode, an improvement in ion conductivity in the dry electrode can be expected. In addition, since the deep eutectic liquid is a liquid, the surface resistance between the living body and the dry electrode can be reduced. As a result, the signal can be acquired immediately after attachment to the skin, and even if moved, there is no baseline shift or the like, and the living body signal can be stably acquired.

[0018] In addition, in Patent Literatures 12, 13, and 14, an electrically conductive resin using a deep eutectic liquid and a method for manufacturing the same, and a sensor provided with the electrically conductive resin are used. The deep eutectic liquid can volatilize in some combinations and form a porous structure. The pressure sensing property of the porous film thus produced is high, and the electrically conductive resin produced by such a method can be used as a resistance change type sensor, and is used for the purpose of attaching to a human body to acquire living body information, but in a living body electrode, resistance change becomes a cause of noise, and thus the electrically conductive resin produced by such a method cannot acquire a stable signal as a living body electrode.

[0019] Furthermore, Patent Literature 15 and Patent Literature 16 disclose a living body electrode and a wearable device using an ionic liquid. The ionic liquid is also a liquid material having the same properties as the deep eutectic liquid, and is considered to have an effect of reducing the surface resistance with a living body when assembled into a living body electrode. However, since the ionic liquid has a risk of biological toxicity in many cases, there are few examples of materials for use in relation to living bodies. In fact, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium tetracyanoborate disclosed in Patent Literature 15 and Patent Literature 16 have a risk of chemical injury and transdermal toxicity, and thus they are considered to be used for short-term wear, and are not materials that can be worn for a long period of time.

[0020] Thus, a living body electrode for a wearable device needs to be able to acquire a signal immediately after attachment to the skin, and to be able to stably acquire a living body signal for a long period of time, but the development of a dry electrode has raised many problems. Therefore, development of a living body electrode composed of a material that is high in ion conductivity and safe even when in contact with a living body, and that can be attached and detached without skin residue or skin irritation, and that can stably acquire a living body signal for a long period of time immediately after attachment to the skin, is required.

[0021] Prior Art Documents

[0022] Patent Literature

[0023] Patent Literature 1: International Publication No. 2013-039151

[0024] Patent Literature 2: Japanese Patent Application Publication No. 2015-100673

[0025] Patent Literature 3: Japanese Patent Application Publication No. H05-095924

[0026] Patent Literature 4: Japanese Patent Application Laid-Open (JP A) No. 2003-225217

[0027] Patent Literature 5: Japanese Patent Application Laid-Open (JP A) No. 2015-019806

[0028] Patent Literature 6: Japanese Patent Application Laid-Open (JP A) No. 2007-059092

[0029] Patent Literature 7: Japanese Patent Application Laid-Open (JP A) No. 2019-180467

[0030] Patent Literature 8: Japanese Patent Application Laid-Open (JP A) No. 2021-115458

[0031] Patent Literature 9: Japanese Patent Application Laid-Open (JP A) No. 2022-075537

[0032] Patent Literature 10: Japanese Patent Application Laid-Open (JP A) No. 2022-075544

[0033] Patent Literature 11: Japanese Patent Application Laid-Open (JP A) No. 2016-538405

[0034] Patent Literature 12: Japanese Patent Application Laid-Open (JP A) No. 2022-085568

[0035] Patent Literature 13: Japanese Patent Application Laid-Open (JP A) No. 2022-085569

[0036] Patent Literature 14: Japanese Patent Application Laid-Open (JP A) No. 2023-176396

[0037] Patent Literature 15: Japanese Patent Application Laid-Open (JP A) No. 2015-016166

[0038] Patent Literature 16: Japanese Patent Application Laid-Open (JP A) No. 2015-077226 SUMMARY

[0039] PROBLEMS TO BE SOLVED BY THE INVENTION

[0040] The present application was made to solve the above problems, and aims to provide a deep eutectic liquid which is high in ion conductivity and safe even when coming into contact with a living body, a living body electrode composition containing the deep eutectic liquid for a living body contact layer of a living body electrode which can form a living body contact layer that adheres to the skin, can rapidly collect a signal, does not cause skin residue, and can stably and long-term obtain a living body signal, a living body electrode in which the living body contact layer is formed with the living body electrode composition, and a production method thereof.

[0041] MEANS FOR SOLVING THE PROBLEMS

[0042] To solve the above problems, the present application provides a deep eutectic liquid which is a mixture of a hydrogen bond-donating compound and a hydrogen bond-accepting compound, wherein the hydrogen bond-donating compound is a compound having a structure in which 2 to 100 monomer bonds having a hydroxyl group are linked, represented by the following general formula (1), the hydrogen bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the following general formulae (2) to (6) or a quaternary phosphonium cation represented by the following general formula (7), and the deep eutectic liquid exists in a liquid form at 25°C.

[0043] [Chemical Formula 1]

[0044]

[0045] In the formula, X represents a single bond, or a 2-valent hydrocarbon group having a linear, branched, or cyclic structure with 1 to 30 carbons which can be substituted with a heteroatom or in which a heteroatom can be inserted. Y and Z represent a 2-valent hydrocarbon group having a linear, branched, or cyclic structure with 1 to 5 carbons which can be substituted with a heteroatom or in which a heteroatom can be inserted. A and B represent a hydrogen atom, a hydroxyl group, an amino group, a halogen atom, or an alkyl group which can be substituted with a heteroatom or in which a heteroatom can be inserted, or an alkyl group terminated with a siloxane. Y and Z can be the same or different. A and B can be the same or different. m is an integer value of 1 to 100, representing the repetition of the chemical structural unit. n is an integer value of 1 to 4, representing the number of repetitions of the chemical structural unit. However, 2 ≤ m x n ≤ 100 is satisfied.

[0046] [Chemical Formula 2]

[0047]

[0048] In the formula, R1 to R 12 are a 1-valent hydrocarbon group having a linear, branched, or cyclic structure with 1 to 30 carbons which can be substituted with a heteroatom or in which a heteroatom can be inserted, a hydrogen atom, a hydroxyl group, an amino group, a nitro group, or a halogen atom. R1 to R 12 may be the same or different.

[0049] If it is such a deep eutectic liquid, it becomes a deep eutectic liquid which is high in ion conductivity and safe even when in contact with a living body.

[0050] In the present application, the monomer having a hydroxyl group is preferably glycerol.

[0051] If it is such a deep eutectic liquid, it becomes a deep eutectic liquid which is higher in ion conductivity and safer even when in contact with a living body.

[0052] At this time, the aforementioned hydrogen bond-donating compound is preferably a polyglycerol-modified polysiloxane represented by the following general formula (8) or (9).

[0053] [Chemical Formula 3]

[0054]

[0055] In the formula, R1' each independently, which can be the same as or different from each other, is a hydrogen atom, a linear or branched alkyl group having a carbon number of 1 to 50, or a phenyl group, can contain an ether group, and can be a polysiloxane chain represented by General Formula (10). R2' is a group having a polyglycerol structure represented by General Formula (8)-1 or General Formula (8)-2. R3' each independently, which can be the same as or different from each other, is R1' or R2' described above. R4' each independently, which can be the same as or different from each other, is R1' described above, R2' described above, or an oxygen atom. When R4' is an oxygen atom, 2 R4' can be bonded to form an ether group and form a ring together with the silicon atom to which they are bonded. a' can be the same as or different from each other, and is 0 to 100, b' is 0 to 100, and a' + b' is 0 to 200. However, when b' is 0, at least one of R3' is R2' described above. R5' is an alkylene group having a carbon number of 2 to 10 or an aralkylene group having a carbon number of 7 to 10. R6' and R7' are alkylene groups having a carbon number of 2 to 6, and R7' can also be an ether group. c' is 0 to 20, and d' is 2 to 20.

[0056] If a deep eutectic liquid using the above-described compound is used, a biological electrode composition containing the same is used for a biological electrode having biocompatibility and ion conductivity, and can rapidly collect signals after being attached to the skin, and can stably and long-term obtain biological signals.

[0057] Further, the present application provides a biological electrode composition, which is a biological electrode composition containing the above-described deep eutectic liquid.

[0058] If the biological electrode composition is as described above, it becomes a biological electrode composition that can form a biological contact layer for a biological electrode that can be attached to the skin to rapidly collect signals, does not cause skin residue, and can stably and long-term obtain biological signals.

[0059] Further, in the present application, the above-described biological electrode composition preferably contains an adhesive (A).

[0060] By containing the adhesive (A) in the biological electrode composition, the above-described deep eutectic liquid can be prevented from dissolving, and adhesiveness can be exhibited.

[0061] At this time, the above-described adhesive (A) is preferably one or more selected from the group consisting of a silicone resin, a polyurethane resin, and a polyacrylic acid resin.

[0062] If the adhesive (A) is as described above, the adhesion to the biological body is good, and skin residue can be prevented.

[0063] Further, in the present application, the aforementioned biological electrode composition preferably contains the conductive particles (B).

[0064] At this time, the aforementioned conductive particles (B) preferably contain one or more selected from the group consisting of carbon powder, gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, molybdenum, ruthenium, and indium.

[0065] At this time, the aforementioned carbon powder is preferably either or both of carbon black and carbon nanotube.

[0066] If the conductive particles (B) are as described above, the surface resistance with respect to the biological electrode and the biological body can be reduced.

[0067] Further, in the present application, furthermore, the aforementioned biological electrode composition preferably contains glycerin.

[0068] The aforementioned biological electrode composition, by containing glycerin, can further reduce the surface resistance with respect to the biological body, and can further improve the ion conductivity.

[0069] Further, the present application provides a biological electrode having a conductive substrate and a biological body contact layer formed on the conductive substrate, and the aforementioned biological body contact layer contains a hardened product of the aforementioned biological electrode composition.

[0070] The biological electrode of the present application, because it has a biological body contact layer containing a hardened product of the aforementioned biological electrode composition, is excellent in conductivity and biocompatibility, is lightweight, and can be manufactured at low cost, can prevent a large reduction in conductivity even if it is wetted with water or dried, does not cause skin residue, and can rapidly collect signals after being attached to the skin.

[0071] At this time, the aforementioned conductive substrate preferably contains one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon.

[0072] In this way, in the biological electrode of the present application, various conductive substrates can be used.

[0073] Further, the present application provides a method for manufacturing a biological electrode, which is a method for manufacturing a biological electrode having a conductive substrate and a biological body contact layer formed on the conductive substrate, and the method forms the biological body contact layer by applying the aforementioned biological electrode composition to the aforementioned conductive substrate and hardening it.

[0074] According to this manufacturing method, a biological electrode that is excellent in conductivity and biocompatibility, is lightweight, can prevent a large reduction in conductivity even if it is wetted with water or dried, can be attached to the skin to rapidly collect signals, and can be easily manufactured at low cost.

[0075] At this time, as the conductive base material, it is preferable to use a conductive base material containing one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon.

[0076] Thus, in the manufacturing method of the biological electrode of the present application, various conductive base materials can be used.

[0077] Further, the present application provides a manufacturing method of a biological electrode, which is a manufacturing method of a biological electrode having a conductive base material and a biological contact layer formed on the conductive base material, in which a biological electrode composition described above is applied on a release base material, hardened, and the patterned one is transferred to the conductive base material to form the biological contact layer.

[0078] If such a manufacturing method, a biological electrode having excellent conductivity and biocompatibility, light weight, preventing a large decrease in conductivity even when wetted with water or dried, capable of being attached to the skin to rapidly collect signals, and designability can be easily manufactured at low cost.

[0079] [Effects of the Invention]

[0080] As described above, if it is the deep eutectic liquid of the present application, it has biocompatibility and ionic conductivity, and can be used for a biological electrode composition. Also, if it is the biological electrode composition of the present application, a biological contact layer for a biological electrode having excellent conductivity and biocompatibility, light weight, and capable of being manufactured at low cost, preventing a large decrease in conductivity even when wetted with water or dried, rapidly collecting signals after being attached to the skin, not causing skin residue, and stably measuring biological signals for a long time can be formed. BRIEF DESCRIPTION OF DRAWINGS

[0081] Figure 1 is a schematic cross-sectional view showing an example of a biological electrode of the present application.

[0082] Figure 2 is a schematic cross-sectional view showing an example of a case where the biological electrode of the present application is mounted on a living body.

[0083] Figure 3 is a schematic view of a biological electrode printed according to an embodiment of the present application.

[0084] Figure 4 is a schematic view of a cut biological electrode according to an embodiment of the present application to which an adhesive layer is attached.

[0085] Figure 5 is a view showing a place where an electrode and a ground wire are attached to a human body when measuring a biological signal according to an embodiment of the present application.

[0086] Figure 6 is a heart rate waveform obtained using a living body electrode of an embodiment of the present application. DETAILED DESCRIPTION

[0087] As described above, there is a demand for developing a deep eutectic liquid having high ion conductivity, which is safe even when it contacts a living body, a living body electrode composition containing the aforementioned deep eutectic liquid, which can rapidly collect a signal after being attached to the skin, does not cause skin residue, and can stably and long-term obtain a living body signal, a living body electrode, and a manufacturing method of a living body electrode.

[0088] Ions of sodium, potassium, and calcium are released from the surface of the skin in synchronization with the beating of the heart. Therefore, it is necessary to convert the increase and decrease of the ions discharged from the skin into an electric signal. Therefore, there is a demand for a material having excellent ion conductivity for transmitting the increase and decrease of ions.

[0089] As a material having ion conductivity, an ionic liquid has been attracting attention. Since these materials exist in a liquid form at room temperature, they exhibit high conductivity while having an organic structure. In addition, since they have the rare property of existing in a liquid form at room temperature although they are ionic compounds, they also have ion conductivity. However, in general, ionic liquids are materials having high toxicity to living bodies, and thus cannot be used for living body electrodes.

[0090] However, there is a material known as a deep eutectic liquid. A deep eutectic liquid is a material that becomes a liquid near room temperature by causing a decrease in the eutectic melting point by mixing a hydrogen bond-donating compound and a hydrogen bond-accepting compound. It is known that a deep eutectic liquid miraculously exhibits properties equivalent to those of an ionic liquid, and the selection of materials is also very wide. Therefore, it has been found that by selecting an ionic compound as a hydrogen bond-accepting compound of a deep eutectic liquid, it is possible to produce a deep eutectic liquid having ion conductivity.

[0091] In addition, when a deep eutectic liquid is used for a living body electrode, biocompatibility is important. Therefore, as a material of a deep eutectic liquid, a compound of a middle molecule to a high molecule such as a saccharide, an amino acid, and the like, which is used in a living body, an oligomer, and a polymer can be considered. If selected from such materials, a deep eutectic liquid having no toxicity to a living body can be obtained.

[0092] However, there are almost no reports on deep eutectic liquids of oligomers and polymers so far, and reports on deep eutectic liquids mainly composed of monomers such as saccharides, amino acids, and the like. Since deep eutectic liquids have been studied as solvents and materials for batteries, and any of them needs to have low viscosity, it is expected that deep eutectic liquids of middle molecules to high molecules have high viscosity, and it is considered that not much research has been conducted so far. In addition, it is considered that the reason is that the degree of freedom of molecular movement of a polymer is low compared to a monomer, and it is difficult to form a hydrogen bond.

[0093] The present inventors have conducted intensive studies on the above problem, and as a result, have found that, interestingly, a deep eutectic liquid using an oligomer having two or more monomers bonded, and that, by using this as a bioelectrode composition, the acquisition of a biological signal can be improved, and have completed the present application.

[0094] That is, the present application is a deep eutectic liquid which is a mixture of a hydrogen bond-donating compound and a hydrogen bond-accepting compound, wherein the hydrogen bond-donating compound is a compound having a structure in which two to 100 monomers having a hydroxyl group are bonded, represented by the following general formula (1), and the hydrogen bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the following general formulae (2) to (6) or a quaternary phosphonium cation represented by the following general formula (7), and the deep eutectic liquid exists in a liquid form at 25°C.

[0095] [Chemical Formula 4]

[0096]

[0097] In the formula, X represents a single bond, or a divalent hydrocarbon group having a linear, branched, or cyclic structure having 1 to 30 carbons which can be substituted with a heteroatom and can have a heteroatom inserted. Y and Z represent a divalent hydrocarbon group having a linear, branched, or cyclic structure having 1 to 5 carbons which can be substituted with a heteroatom. A and B represent a hydrogen atom, a hydroxyl group, an amino group, a halogen atom, or an alkyl group which can be substituted with a heteroatom or an alkyl group substituted at the end with a siloxane. Y and Z can each be the same or different. A and B can each be the same or different. m is an integer value of 1 to 100, and represents the number of repetitions of the chemical structure unit. n is an integer value of 1 to 4, and represents the number of repetitions of the chemical structure unit. However, 2 ≤ m x n ≤ 100 is satisfied.

[0098] [Chemical Formula 5]

[0099]

[0100] In the formula, R1 to R 12 is a monovalent hydrocarbon group having a linear, branched, or cyclic structure having 1 to 30 carbons which can be substituted with a heteroatom and can have a heteroatom inserted, a hydrogen atom, a hydroxyl group, an amino group, a nitro group, or a halogen atom. R1 to R 12 can each be the same or different.

[0101] The deep eutectic liquid and the biological electrode composition of the present application can form a biological contact layer for a biological electrode which is excellent in conductivity and biocompatibility, light in weight, can be manufactured at low cost, can prevent a large decrease in conductivity or adhesion regardless of wetting by water or drying, can rapidly collect signals when attached to the skin, does not cause skin residue, and can stably obtain biological signals for a long period of time.

[0102] Hereinafter, the present application will be described in detail, but the present application is not limited to these.

[0103] [Deep eutectic liquid]

[0104] The deep eutectic liquid of the present application is a deep eutectic liquid which is a mixture of a hydrogen bond-donating compound and a hydrogen bond-accepting compound, the hydrogen bond-donating compound is a compound having a structure in which 2 to 100 monomer bonds having a hydroxyl group are bonded, represented by the following general formula (1), the hydrogen bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the following general formulae (2) to (6) or a quaternary phosphonium cation represented by the following general formula (7), and the deep eutectic liquid exists in a liquid form at 25°C.

[0105] [Chemical formula 6]

[0106]

[0107] In the formula, X represents a single bond, or a linear, branched, or cyclic divalent hydrocarbon group having 1 to 30 carbons which can be substituted with a heteroatom and can have a heteroatom inserted. Y and Z represent a linear, branched, or cyclic divalent hydrocarbon group having 1 to 5 carbons which can be substituted with a heteroatom. A and B represent a hydrogen atom, a hydroxyl group, an amino group, a halogen atom, or an alkyl group which can be substituted with a heteroatom or an alkyl group having a terminal siloxane substituted. Y and Z can be the same or different. A and B can be the same or different. m is an integer value of 1 to 100, and represents the number of repetitions of the chemical structure unit. n is an integer value of 1 to 4, and represents the number of repetitions of the chemical structure unit. However, 2 ≤ m x n ≤ 100 is satisfied.

[0108] [Chemical formula 7]

[0109]

[0110] In the formula, R1 to R 12 is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 30 carbons which can be substituted with a heteroatom and can have a heteroatom inserted, a hydrogen atom, a hydroxyl group, an amino group, a nitro group, or a halogen atom, which can be a zwitterion having an anionic portion. R1 to R 12 Each can be the same or different.

[0111] The hydrogen bond donating compound is a compound represented by the above general formula (1) having a structure in which 2 to 100 monomers having a hydroxyl group are bonded. Specifically, as the monomer having a hydroxyl group, there can be mentioned vinyl alcohol, glycerol, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, propylene glycol monoacrylate, 4-vinylphenol, 4-allylphenol, 4-vinyl-1,2-benzenediol, 4-allyl-1,2-benzenediol, and the like. In the present application, the monomer having a hydroxyl group is preferably glycerol, and the hydrogen bond donating compound is further preferably a polyglycerol-modified polysiloxane represented by the above general formula (8) or (9).

[0112] [Chem. 8]

[0113]

[0114] In the formula, R1' each independently, which can be the same as or different from each other, is a hydrogen atom, a linear or branched alkyl group having a carbon number of 1 to 50, or a phenyl group, can contain an ether group, and can be a polysiloxane chain represented by general formula (10). R2' is a group having a polyglycerol structure represented by general formula (8)-1 or general formula (8)-2. R3' each independently, which can be the same as or different from each other, is R1' or the aforementioned R2'. R4' each independently, which can be the same as or different from each other, is R1', the aforementioned R2, or an oxygen atom. When R4' is an oxygen atom, 2 R4' can be bonded to form an ether group, together with the silicon atom to which they are bonded, to form a ring. a' can be the same as or different from each other, and is 0 to 100, b' is 0 to 100, and a' + b' is 0 to 200. Among them, when b' is 0, at least one of R3' is the aforementioned R2'. R5' is an alkylene group having a carbon number of 2 to 10 or an aralkylene group having a carbon number of 7 to 10. R6' and R7' are alkylene groups having a carbon number of 2 to 6, and R7' can be an ether group. c' is 0 to 20, and d' is 2 to 20.

[0115] The polyglycerol-modified polysiloxane has, for example, the following structure.

[0116] [Chem. 9]

[0117]

[0118] [Chem. 10]

[0119]

[0120] [Chem. 11]

[0121]

[0122] [Chem. 12]

[0123]

[0124] [Chemical 13]

[0125]

[0126] [Chemical 14]

[0127]

[0128] [Chemical 15]

[0129]

[0130] [Chemical 16]

[0131]

[0132] [Chemical 17]

[0133]

[0134] [Chemical 18]

[0135]

[0136] wherein a', b', c', and d' are as described above.

[0137] The above-mentioned hydrogen-bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the above-mentioned general formulae (2) to (6) or a quaternary phosphonium cation represented by the above-mentioned general formula (7). Specifically, mention can be made of choline chloride, betaine, tetrabutylammonium chloride, and the like ammonium salts, imidazolium salts containing a 1-ethyl-3-methylimidazolium cation, a 1-butyl-3-methylimidazolium cation, pyridinium salts such as 1-butylpyridinium chloride, pyrrolidinium salts such as 1-butyl-1-methylpyrrolidinium chloride, piperidinium salts such as 1-butyl-1-methylpiperidinium chloride, and phosphonium salts such as tributyl(methyl)phosphonium dimethylphosphate. The biocompatible hydrogen-bond-accepting compound is not limited to the above-mentioned compounds, and, for example, derivatives thereof also become candidates for a deep eutectic liquid material.

[0138] In many cases, a deep eutectic liquid is obtained by mixing the biocompatible hydrogen-bond-donating compound and the biocompatible hydrogen-bond-accepting compound in the same molar amount. Deep eutectic liquids are also observed at other molar ratios, for example, molar ratios of 1:1 to 10:1, 1:1 to 5:1.

[0139] [Bioelectrode composition]

[0140] The present application provides a bioelectrode composition containing the above-mentioned deep eutectic liquid.

[0141] [Binder (A)]

[0142] The living body electrode composition of the present application can contain a binder (A) in addition to the deep eutectic liquid described above. That is, the aforementioned living body electrode composition preferably contains a binder (A). For example, the living body electrode composition of the present application can contain one or more resins selected from the group consisting of a silicone-based resin, an acrylic-based resin, and a urethane-based resin. That is, the aforementioned binder (A) is preferably one or more resins selected from the group consisting of a silicone-based resin, a urethane-based resin, and a polyacrylic-based resin. By containing one or more resins selected from the group consisting of a silicone-based resin, an acrylic-based resin, and a urethane-based resin, a living body electrode comprising a living body contact layer excellent in stretchability can be provided.

[0143] The binder (A) that can be blended in the living body electrode composition of the present application, for example, can serve as a component to prevent elution of the deep eutectic liquid described above and to exhibit adhesiveness. In the case where the living body electrode composition contains the electrically conductive particles (B) described later, the binder (A) can hold these powders. Also, the binder (A) can be either or both of a thermally curable resin and a photo-curable resin, and is particularly preferably one or more resins selected from the group consisting of a silicone-based resin, an acrylic-based resin, and a urethane-based resin.

[0144] As the silicone-based resin for adhesiveness, an addition reaction hardening type or a radical crosslinking hardening type silicone-based resin can be exemplified. As the addition reaction hardening type, for example, a silicone-based resin containing a diorganosiloxane having an alkenyl group described in Japanese Patent Application Laid-Open No. 2015-193803, an MQ resin having an SiO2 unit, an organohydrogenpolysiloxane having a plurality of SiH groups, a platinum catalyst, an addition reaction control agent, and an organic solvent can be used. In addition, as the radical crosslinking reaction hardening type, for example, a silicone-based resin containing a diorganopolysiloxane which can have or not have an alkenyl group described in Japanese Patent Application Laid-Open No. 2015-193803, an MQ resin having an SiO2 unit, an organic peroxide, and an organic solvent can be used. Here, R is a substituted or unsubstituted monovalent hydrocarbon group having a carbon number of 1 to 10. 0.5 and an SiO2 unit, an organohydrogenpolysiloxane having a plurality of SiH groups, a platinum catalyst, an addition reaction control agent, and an organic solvent. In addition, as the radical crosslinking reaction hardening type, for example, a silicone-based resin containing a diorganopolysiloxane which can have or not have an alkenyl group described in Japanese Patent Application Laid-Open No. 2015-193803, an MQ resin having an SiO2 unit, an organic peroxide, and an organic solvent can be used. Here, R is a substituted or unsubstituted monovalent hydrocarbon group having a carbon number of 1 to 10. 0.5 and an SiO2 unit, an organohydrogenpolysiloxane having a plurality of SiH groups, a platinum catalyst, an addition reaction control agent, and an organic solvent. In addition, as the radical crosslinking reaction hardening type, for example, a silicone-based resin containing a diorganopolysiloxane which can have or not have an alkenyl group described in Japanese Patent Application Laid-Open No. 2015-193803, an MQ resin having an SiO2 unit, an organic peroxide, and an organic solvent can be used. Here, R is a substituted or unsubstituted monovalent hydrocarbon group having a carbon number of 1 to 10.

[0145] In addition, a polysiloxane·resin integrated compound formed by condensation reaction of a polysiloxane having a silanol at the terminal of a polymer or a side chain with an MQ resin can also be used. The MQ resin contains a large amount of silanol, and thus adhesiveness is improved by adding it, but since it has no crosslinking property, it is not molecularly bonded to the polysiloxane. As described above, by integrating the polysiloxane and the resin, it is possible to increase adhesiveness.

[0146] In addition, a modified siloxane having a group selected from the group consisting of an amino group, an oxiranyl group, an oxetanyl group, a polyether group, a hydroxyl group, a carboxyl group, a mercapto group, a methacrylic acid group, an acrylic acid group, a phenol group, a silanol group, a carboxylic anhydride group, an aryl group, an aralkyl group, an amide group, an ester group, an internal lactone ring can be added to the polysiloxane resin. By adding the modified siloxane, dispersibility of the deep eutectic liquid in the polysiloxane resin is improved. The modified siloxane can be a siloxane in which any one of a single end, both ends, or a side chain is modified.

[0147] As the adhesive acrylic resin, for example, an acrylic resin having a hydrophilic (meth)acrylate and a long-chain hydrophobic (meth)acrylate as a repeating unit described in Japanese Patent Application Publication No. 2016-011338 can be used. Depending on the case, a (meth)acrylate having a functional group, a (meth)acrylate having a siloxane bond can be copolymerized.

[0148] As the adhesive polyurethane resin, for example, a resin having a urethane bond, and a polyether, a polyester bond, a polycarbonate bond, a siloxane bond described in Japanese Patent Application Publication No. 2016-065238 can be used.

[0149] In addition, in order to prevent the biological contact layer from peeling from the conductive substrate, the binder (A) in the biological electrode composition of the present application is preferably one having high adhesion to the conductive substrate. In order to make the binder (A) have high compatibility with the conductive substrate and the salt, it is effective to use a resin having high polarity. As such a resin, a resin having one or more selected from the group consisting of an ether bond, an ester bond, an amide bond, an imide bond, a urethane bond, a thiourethane bond, and a thiol group, or a polyacrylic resin, a polyamide resin, a polyimide resin, a polyurethane resin, and a polythiourethane resin, etc. can be given. In addition, on the other hand, since the biological contact layer contacts the living body, it is easily affected by sweat from the living body. Therefore, the binder (A) in the biological electrode composition of the present application is preferably one having high water repellency and is not easily hydrolyzed. In order to make the binder have high water repellency and not be easily hydrolyzed, it is effective to use a resin containing a silicon atom.

[0150] As the polyacrylic resin containing a silicon atom, a polymer having a polysiloxane in the main chain and a polymer having a silicon atom in the side chain can be used, and either one is desirable. As the polymer having a polysiloxane in the main chain, a siloxane or a silsesquioxane having a (meth)acrylic acid group propyl group, etc. can be used. In this case, by adding a photoradical generator, the (meth)acrylic acid portion can be partially polymerized and hardened.

[0151] As the polyamide resin containing a silicon atom, for example, a polyamide polysiloxane described in Japanese Patent Application Publication No. 2011-079946, U.S. Patent No. 5981680, or the like can be preferably used. Such a polyamide polysiloxane can be synthesized, for example, by combining a polysiloxane compound having an amino group at both terminals or a non-polysiloxane compound having an amino group at both terminals with a non-polysiloxane compound having a carboxyl group at both terminals or a polysiloxane compound having a carboxyl group at both terminals.

[0152] In addition, a polyamic acid before cyclization obtained by reacting a carboxylic anhydride with an amine can also be used. In the crosslinking of the carboxyl group of the polyamic acid, an epoxy-based or oxetane-based crosslinking agent can be used, or an esterification reaction of the carboxyl group with hydroxyethyl (meth)acrylate can be performed, and a photoradical crosslinking of the (meth)acrylate moiety can be performed.

[0153] As the polyimide resin containing a silicon atom, for example, a polyimide polysiloxane described in Japanese Patent Application Publication No. 2002-332305, or the like can be preferably used. The polyimide resin has very high viscosity, but by blending a (meth)acrylic monomer as a solvent and as a crosslinking agent, it can be made to have low viscosity.

[0154] As the polyurethane resin containing a silicon atom, a polyurethane polysiloxane can be exemplified. In such a polyurethane polysiloxane, crosslinking using a urethane bond can be performed by mixing a compound having an isocyanate group at both terminals with a compound having a hydroxyl group at a terminal and heating. In this case, either one or both of the compound having an isocyanate group at both terminals or the compound having a hydroxyl group at a terminal must contain a silicon atom (siloxane bond). Alternatively, as described in Japanese Patent Application Publication No. 2005-320418, a urethane (meth)acrylate monomer can be mixed in a polysiloxane and made to be photocrosslinked. In addition, a polymer having both a siloxane bond and a urethane bond and having a (meth)acrylate group at a terminal can be made to be photocrosslinked. In particular, a polyurethane having a siloxane chain in a side chain and a main chain described in Japanese Patent Application Publication No. 2018-123304, Japanese Patent Application Publication No. 2019-070109 has a high strength and a high stretch characteristic, and thus is desirable.

[0155] A polythiourethane resin containing a silicon atom can be obtained by the reaction of a compound having a thiol group with a compound having an isocyanate group, as long as either one of them contains a silicon atom. In addition, if a (meth)acrylate group is present at a terminal, it can also be photocured.

[0156] In the polysiloxane-based resin, in addition to the above-described diorganosiloxane having an alkenyl group, a diorganosiloxane having R3SiO 0.5In addition to the organohydrogenpolysiloxane having a plurality of SiH groups, the MQ resin with SiO2 units can improve the compatibility with the conductive base material and the salt by adding a modified siloxane having a group selected from the group consisting of an amino group, an oxiranyl group, an oxetanyl group, a polyether group, a hydroxyl group, a carboxyl group, a mercapto group, a methacrylic acid group, an acrylic acid group, a phenol group, a silanol group, a carboxylic anhydride group, an aryl group, an aralkyl group, an amide group, an ester group, and a lactone ring.

[0157] In the living body electrode composition of the present application, the blending amount of the binder (A) is preferably 0 to 2,000 parts by mass and more preferably 10 to 1,000 parts by mass with respect to 100 parts by mass of the deep eutectic liquid. In addition, the binder (A) can be used alone or in combination with two or more kinds.

[0158] Further, as described later, the living body electrode of the present application has a hardened product of the living body electrode composition containing the deep eutectic liquid. By hardening the living body electrode composition, the adhesion of the living body contact layer to both the skin and the conductive base material becomes good. Also, as the hardening means, there is no particular limitation, and a general means can be used, for example, a cross-linking reaction using either or both of heat and light, or an acid catalyst or a base catalyst, or the like can be used. As for the cross-linking reaction, for example, a method described in Chapter 2, p51 to p371 of "Cross-linking Reaction Manual", Yoko Yamazaki, Maruzen Publishing (2013) can be appropriately selected and performed.

[0159] The diorganosiloxane having an alkenyl group and the organohydrogenpolysiloxane having a plurality of SiH groups can be cross-linked by an addition reaction using a platinum catalyst.

[0160] As the platinum catalyst, a platinum-based catalyst such as chloroplatinic acid, an alcohol solution of chloroplatinic acid, a reaction product of chloroplatinic acid and an alcohol, a reaction product of chloroplatinic acid and an olefin compound, a reaction product of chloroplatinic acid and a siloxane containing a vinyl group, a platinum-olefin complex, a platinum-siloxane containing a vinyl group complex, and a platinum group metal-based catalyst such as a rhodium complex and a ruthenium complex, and the like can be mentioned. In addition, a substance in which these catalysts are dissolved or dispersed in an alcohol-based, a hydrocarbon-based, or a siloxane-based solvent can also be used.

[0161] Also, the addition amount of the platinum catalyst is preferably set to a range of 5 to 2,000 ppm and particularly preferably 10 to 500 ppm with respect to 100 parts by mass of the binder (A).

[0162] In addition, in the case of using an addition-curable silicone, an addition reaction control agent can be added. This addition reaction control agent is added as a quenching agent for inactivating the platinum catalyst in a low-temperature environment after the formation of a solution and a coating film and before the heat curing. Specifically, 3-methyl-1-butyne-3-ol, 3-methyl-1-pentyne-3-ol, 3,5-dimethyl-1-hexyne-3-ol, 1-ethynylcyclohexanol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentyne, 3,5-dimethyl-3-trimethylsiloxy-1-hexyne, 1-ethynyl-1-trimethylsiloxy cyclohexane, bis(2,2-dimethyl-3-butyneoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 1,1,3,3-tetramethyl-1,3-divinyl disiloxane, etc. can be mentioned.

[0163] The addition amount of the addition reaction control agent is preferably in the range of 0 to 10 parts by mass, and particularly preferably in the range of 0.05 to 3 parts by mass, relative to 100 parts by mass of the binder (A).

[0164] As a method of performing photo-curing, a method of using a resin having a (meth)acrylate terminal, an olefin terminal, or adding a cross-linking agent having a (meth)acrylate, an olefin, a thiol group as a terminal, and adding a photo-radical generator that generates radicals by light can be mentioned. A method of using a resin, a cross-linking agent having an oxirane group, an oxetane group, a vinyl ether group, and adding a photo-acid generator that generates an acid by light can be mentioned.

[0165] As the photoradical generator, benzophenone, 4,4'-dimethoxybenzil, benzil, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin isobutyl ether, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2-benzoylbenzoic acid methyl ester, 2-(1,3-benzodioxol-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'-dichlorobenzophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,4-diethylthioxanthone-9-ketone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), 1,4-benzoylbenzene, 2-ethylanthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-isonitrosopropiophenone, and 2-phenyl-2-(p-toluenesulfonyloxy)propiophenone can be mentioned.

[0166] The curable composition can also be hardened by adding a thermally decomposable radical generator. As the thermally decomposable radical generator, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(methylpropionamidine) hydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] hydrochloride, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(cyclohexane-1-carbonitrile), 1[(1-cyano-1-methylethyl)azo]formamide, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), dimethyl-2,2'-azobis(isobutyrate), 4,4'-azobis(4-cyanopentanoic acid), dimethyl-2,2'-azobis(2-methylpropionate), benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, di-t-butyl peroxide, di-t-amyl peroxide, di-n-butyl peroxide, di-cumyl peroxide, and the like can be mentioned.

[0167] As the photoacid generator, mention can be made of a sulfonium salt, a sulfoxonium salt, a sulfonyldiazo methane, an N-sulfonyloxy imide, and an oxime-O-sulfonic acid type acid generator. As specific examples of the photoacid generator, mention can be made of the photoacid generators described in

[0122] to

[0142] of Japanese Patent Application Publication No. 2008-111103, and Japanese Patent Application Publication No. 2009-080474.

[0168] Further, the addition amount of the radical generator and the photoacid generator is preferably in the range of 0.1 to 50 parts by mass with respect to 100 parts by mass of the binder (A).

[0169] Among these, as the binder (A), it is preferable to use a polysiloxane having R x SiO (4-x) / 2 (R is a substituted or unsubstituted monovalent hydrocarbon group having a carbon number of 1 to 10, and x is in the range of 2.5 to 3.5.) and a SiO2 unit, a diorganosiloxane having an alkenyl group, and an organohydrogen polysiloxane having an SiH group. Such a binder (A) is compatible with the deep eutectic liquid described above, prevents the elution of salts, and imparts higher adhesiveness to the living body contact layer.

[0170] [Conductive particles (B)]

[0171] Further, the aforementioned living body electrode composition preferably contains the conductive particles (B). The conductive particles (B) are, specifically, for example, carbon powder, metal powder, and the like. That is, the aforementioned conductive particles (B) preferably contain one or more selected from the group consisting of carbon powder, gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, molybdenum, ruthenium, and indium.

[0172] [Metal powder]

[0173] In the living body electrode composition of the present application, in order to improve the conductivity, a metal powder selected from the group consisting of gold, silver, silver chloride, platinum, copper, tin, titanium, nickel, aluminum, magnesium, tungsten, steel, stainless steel, molybdenum, ruthenium, chromium, and indium can also be added. The addition amount of the metal powder is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the binder (A).

[0174] As the kind of the metal powder, from the viewpoint of the conductivity, gold, silver, and platinum are preferable, and from the viewpoint of the price, silver, copper, tin, titanium, nickel, aluminum, tungsten, molybdenum, ruthenium, and chromium are preferable. From the viewpoint of the biocompatibility, a noble metal is preferable. In view of these points, silver is the most preferable.

[0175] As the shape of the metal powder, mention can be made of a spherical shape, a disc shape, a flaky shape, and a needle shape, but the conductivity is the highest when the flaky powder is added, and thus the flaky shape is the most preferable. The size of the metal powder is 100 μm or less, and the tap density is 5 g / cm 3 In the following, the specific surface area is 0.5 m2 A chip having a density of 1.0 g / cm3 or more and a specific surface area of 1.0 m2 / g or more is preferable. Here, the size is a value obtained by a laser diffraction method, the tap density (tap bulk density) is a value measured by a Powder Tester PT-X manufactured by Holikawa Micron Co., Ltd., and the specific surface area is a value measured by liquid nitrogen adsorption (77 K) (Microtrac BEL, BELSORP-max) according to a specific surface area measurement method of a powder based on gas adsorption.

[0176] [Carbon powder]

[0177] As the conductive particles (B), a carbon powder can be added. As the carbon powder (carbon material), for example, carbon black, graphite, a carbon nanotube, a carbon fiber, or the like can be given. The carbon nanotube can be any one of a single layer and a multi layer, and can be modified with an organic group. The addition amount of the carbon material is preferably in a range of 1 to 50 parts by mass with respect to 100 parts by mass of the binder (A). The aforementioned carbon powder is preferably any one or both of carbon black and a carbon nanotube.

[0178] [Organic solvent]

[0179] Further, an organic solvent can be added to the living electrode composition of the present application. As the organic solvent, specifically, aromatic hydrocarbon-based solvents such as toluene, xylene, cumene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, styrene, alpha-methylstyrene, butylbenzene, sec-butylbenzene, isobutylbenzene, cymene, diethylbenzene, 2-ethyl-p- xylene, 2-propyltoluene, 3-propyltoluene, 4-propyltoluene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, tetralin, 4-phenyl-l-butene, tert-amylbenzene, amylbenzene, 2-tert-butyltoluene, 3-tert-butyltoluene, 4-tert-butyltoluene, 5-isopropyl-m-xylene, 3-methylethylbenzene, tert-butyl-3-ethylbenzene, 4-tert-butyl-o-xylene, 5-tert-butyl-m-xylene, tert-butyl-p-xylene, 1,2-diisopropylbenzene, 1,3-diisopropylbenzene, 1,4-diisopropylbenzene, dipropylbenzene, pentamethylbenzene, hexamethylbenzene, hexylbenzene, and 1,3,5-triethylbenzene; n-heptane, isoheptane, 3-methylhexane, 2,3-dimethylpentane, 3-ethylpentane, 1,6-heptadiene, 5-methyl-l-hexyne, norbornane, norbornene, dicyclopentadiene, 1-methyl-l,4-cyclohexadiene, 1-heptyne, 2-heptyne, cycloheptane, cycloheptene, 1,3-dimethylcyclopentane, ethylcyclopentane, methylcyclohexane, 1-methyl-l-cyclohexene, 3-methyl-l-cyclohexene, methylene-cyclohexane, 4-methyl-l-cyclohexene, 2-methyl-l-hexene, 2-methyl-2-hexene, 1-heptene, 2-heptene, 3-heptene, n-octane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,3-dimethylhexane, 3,4-dimethylhexane, 3-ethyl-2-methylpentane, 3-ethyl-3-methylpentane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane, cyclooctane, cyclooctene, 1,2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, ethylcyclohexane,2,4,4-Tetramethylpentane, 2,2,4-Trimethylhexane, 2,2,5-Trimethylhexane, 2,2-Dimethyl-3-heptene, 2,3-Dimethyl-3-heptene, 2,4-Dimethyl-1-heptene, 2,6-Dimethyl-1-heptene, 2,6-Dimethyl-3-heptene, 3,5-Dimethyl-3-heptene, 2,4,4-Trimethyl-1-hexene, 3,5,5-Trimethyl-1-hexene, 1-Ethyl-2-methylcyclohexane, 1-Ethyl-3-methylcyclohexane, 1-Ethyl-4-methylcyclohexane, Propylcyclohexane, Isopropylcyclohexane, 1,1,3-Trimethylcyclohexane Hexane, 1,1,4-trimethylcyclohexane, 1,2,3-trimethylcyclohexane, 1,2,4-trimethylcyclohexane, 1,3,5-trimethylcyclohexane, allylcyclohexane, hydrindane, 1,8-nonadiene, 1-nonyne, 2-nonyne, 3-nonyne, 4-nonyne, 1-nonene, 2-nonene, 3-nonene, 4-nonene, n-decane, 3,3-dimethyloctane, 3,5-dimethyloctane, 4,4-dimethyloctane, 3-ethyl-3-methylheptane, 2-methylnonane, 3-methylnonane, 4-methylnonane, tert-butylcyclohexane, butylcyclohexane, iso... Butylcyclohexane, 4-isopropyl-1-methylcyclohexane, pentylcyclopentane, 1,1,3,5-tetramethylcyclohexane, cyclododecane, 1-decene, 2-decene, 3-decene, 4-decene, 5-decene, 1,9-decadiene, decahydronaphthalene, 1-decyne, 2-decyne, 3-decyne, 4-decyne, 5-decyne, 1,5,9-decytriene, 2,6-dimethyl-2,4,6-octtriene, limonene, myrcene, 1,2,3,4,5-pentamethylcyclopentadiene, α-phellandrene, pinene, terpinene, tetrahydrodicyclopentadiene, 5,6-Dihydrodicyclopentadiene, dicyclopentadiene, 1,4-decadiyne, 1,5-decadiyne, 1,9-decadiyne, 2,8-decadiyne, 4,6-decadiyne, n-Undecane, pentylcyclohexane, 1-Undecane, 1,10-Undecadiene, 1-Undecane, 3-Undecane, 5-Undecane, tricyclo[6.2.1.02,ene, n-Dodecane, 2-Methylundecane, 3-Methylundecane, 4-Methylundecane, 5-Methylundecane, 2,2,4,6,6-Pentamethylheptane, 1,3-Dimethyladamantane, 1-Ethyladamantane, 1,5,9-Cyclododecanetriene, 1,2,4-trivinylcyclohexane, and aliphatic hydrocarbon solvents such as isoparaffin, cyclohexanone, cyclopentanone, 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, methyl n-amyl ketone, and ketone solvents such as methyl n-amyl ketone, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and alcohol solvents such as 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monoheptyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, diisopropyl ether, diisobutyl ether, diisopentyl ether, di-n-pentyl ether, methylcyclopentyl ether, methylcyclohexyl ether, di-n-butyl ether, di-sec-butyl ether, di-sec-pentyl ether, di-t-pentyl ether, di-n-hexyl ether, and benzyl ether, and ether solvents such as benzyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, t-butyl acetate, t-butyl propionate, and propylene glycol mono-t-butyl ether acetate, ester solvents such as t-butyl acetate, t-butyl propionate, and propylene glycol mono-t-butyl ether acetate, lactone solvents such as γ-butyrolactone, and the like.

[0180] Further, in the living body electrode composition of the present application, water can be added as a solvent.

[0181] As the amount of water to be added, it is preferable to be in the range of 70 to 150 parts by mass relative to 100 parts by mass of the binder (A).

[0182] [Adhesion-imparting agent]

[0183] Further, in the living body electrode composition of the present application, an adhesion-imparting agent can be added in order to impart adhesion to a living body. As such an adhesion-imparting agent, for example, polysiloxane, non-crosslinking silicone, non-crosslinking poly(meth)acrylate, non-crosslinking polyether, and the like can be exemplified. As the amount to be added, it is preferable to be in the range of 1 to 20 parts by mass relative to 100 parts by mass of the binder (A).

[0184] [Crosslinking agent]

[0185] In the living body electrode composition of the present application, an epoxy-based crosslinking agent can be added. In this case, the crosslinking agent is a compound having a plurality of epoxy groups, oxetane groups in one molecule. As the amount to be added, it is preferable to be in the range of 1 to 30 parts by mass relative to 100 parts by mass of the binder (A).

[0186] [Crosslinking catalyst]

[0187] In the living body electrode composition of the present application, a cross-linking catalyst for cross-linking the epoxy group and the oxetane group described above can also be added. The cross-linking catalyst at this time can be, for example, those described in Japanese Patent Application Laid-Open No. 2019-503406

[0027] to

[0029] . As the amount of addition, it is preferable to set to a range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the binder (A).

[0188] [Ionic additive]

[0189] In the living body electrode composition of the present application, an ionic additive for improving ion conductivity can be added. If biocompatibility is taken into consideration, sodium chloride, potassium chloride, calcium chloride, saccharin, acesulfame potassium, salts described in Japanese Patent Application Laid-Open No. 2018-044147, Japanese Patent Application Laid-Open No. 2018-059050, Japanese Patent Application Laid-Open No. 2018-059052, and Japanese Patent Application Laid-Open No. 2018-130534 can be mentioned.

[0190] Further, the aforementioned living body electrode composition preferably contains glycerin. As the amount of addition, it is preferable to set to a range of 1 to 30 parts by mass with respect to 100 parts by mass of the binder (A).

[0191] [Compound (C) having a polyglycerin structure]

[0192] In the living body electrode composition of the present application, a compound (C) having a polyglycerin structure can be added in order to improve ion conductivity and reduce contact impedance with the skin. As the compound (C) having a polyglycerin structure, for example, polyglycerin (2 to 10-mer of glycerin), polyglycerin-modified polysiloxane (polyglyceryl-3 polydimethylsiloxyethyl dimethicone, lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone) can be mentioned. As the amount of addition, it is preferable to set to a range of 1 to 30 parts by mass with respect to 100 parts by mass of the binder (A).

[0193] As described above, if the biological electrode composition of the present application is used, a biological contact layer for a biological electrode having excellent conductivity and biocompatibility, being lightweight, and being able to be produced at low cost, can be formed, and even if it is wetted with water or dried, a large decrease in conductivity can be prevented, signals can be rapidly collected after being attached to the skin, and skin residue can not be caused. Since the biological contact layer formed by hardening the biological electrode composition of the present application can exhibit excellent conductivity, electric signals from a living body such as the skin can be efficiently transmitted to a device. In addition, since the biological contact layer can exhibit excellent biocompatibility, even if it is worn on the skin for a long time, an allergy can be prevented. In addition, by adding a conductivity improver such as a carbon material, the conductivity can be further improved. Furthermore, the biological electrode composition of the present application, by being combined with a resin having adhesiveness and stretchability, can produce a biological electrode having particularly high adhesiveness and high stretchability. Moreover, the biological electrode composition of the present application, by adding an additive or the like, the stretchability and adhesiveness to the skin can be improved. Also, by appropriately adjusting the kind and amount of the deep eutectic liquid, the composition of the binder (A), or the amount of the conductive particles (B) used in the biological electrode composition of the present application, or the thickness of the biological contact layer, the stretchability or the adhesiveness can also be adjusted.

[0194] <biological electrode>

[0195] Also, the present application provides a biological electrode having a conductive substrate and a biological contact layer formed on the conductive substrate, and the biological contact layer contains a hardened product of the biological electrode composition described above.

[0196] Hereinafter, the biological electrode of the present application will be described in detail with reference to the drawings, but the present application is not limited to these.

[0197] Figure 1 is a schematic cross-sectional view showing an example of the biological electrode of the present application. Figure 1 The biological electrode 1 of is provided with a conductive substrate 2 and a biological contact layer 3 formed on the conductive substrate 2. The biological contact layer 3 is a layer in which a deep eutectic liquid 5 and conductive particles 4 are dispersed in a resin 6. The resin 6 is, for example, the polymer (C) having a polyglycerol structure and the binder polymer (A) described above. The biological contact layer 3 is an example of a hardened product of the biological electrode composition of the present application.

[0198] When the biological contact layer 3 of is used, as in Figure 1 Figure 2 ​The biological contact layer 3 (i.e., the layer in which the deep eutectic liquid 5 and the electrically conductive particles 4 are dispersed in the resin 6) is brought into contact with the living body 7, the electrical signal is extracted from the living body 7 by the deep eutectic liquid 5 and the electrically conductive particles 4, and is conducted to a sensor device or the like (not shown) via the electrically conductive base material 2. Thus, if the biological contact layer is a hardened product of the biological electrode composition of the present application, the electrical conductivity and the biocompatibility are both achieved by the deep eutectic liquid as described above, and the adhesiveness is also high, so the contact area with the skin is constant, and the electrical signal from the skin can be stably obtained with high sensitivity. In particular, as described above, the biological electrode composition of the present application can form a biological contact layer that can be attached to the skin and rapidly collect signals. Thus, Figure 1 The biological electrode 1 of the present application can be attached to the living body 7 and rapidly collect signals as Figure 2

[0199] Hereinafter, each constituent material of the biological electrode of the present application will be described in more detail.

[0200] [Electrically conductive base material]

[0201] The biological electrode of the present application has an electrically conductive base material. The electrically conductive base material is usually electrically connected to a sensor device or the like, and conducts the electrical signal extracted from the living body via the biological contact layer to the sensor device or the like.

[0202] As the electrically conductive base material, there is no particular limitation as long as it has electrical conductivity, and for example, it is preferably composed of one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon.

[0203] In addition, the electrically conductive base material is not particularly limited, and can be a hard electrically conductive substrate or the like, or a flexible electrically conductive film, a substrate on which an electrically conductive paste is applied to a film having stretchability, a cloth on which an electrically conductive paste is applied to the surface, or a cloth in which an electrically conductive polymer is kneaded. The electrically conductive base material can be flat, or can have a concave-convex shape, or can be a mesh formed of braided metal wires, and can be appropriately selected depending on the purpose of the biological electrode or the like. Among them, in view of use attached to the skin, a stretchable film or a substrate on which an electrically conductive paste is applied to a cloth is preferable. As the stretchable film, polyurethane, polyester can be given. As the electrically conductive paste, an electrically conductive paste in which an electrically conductive powder such as carbon, silver, gold, copper, or the like is mixed in a solvent in a stretchable resin such as polyurethane, polyester, polysiloxane, nitrile resin, or the like is used.

[0204] [Biological contact layer]

[0205] ​The living body contact layer of the present application has a living body contact layer formed on a conductive base material. The living body contact layer is the portion that actually contacts the living body when the living body contact layer is used, and has conductivity. The living body contact layer is an adhesive resin layer that contains, in addition to the deep eutectic liquid described above, an adhesive agent (A), conductive particles (B), glycerin, and an additive such as a compound (C) having a polyglycerin structure.

[0206] Further, the adhesive force of the living body contact layer is preferably in the range of 0.5 N / 24 mm or more and 20 N / 24 mm or less. The measurement method of the adhesive force is generally the method shown in JIS Z 0237, and as the base material, a metal substrate such as SUS (stainless steel), a PET (polyethylene terephthalate) substrate can be used, but the measurement can also be performed using human skin. Therefore, the surface energy of human skin is lower than that of metals and various plastics, and is a low energy close to Teflon (registered trademark). Therefore, human skin has a property of not easily adhering.

[0207] The thickness of the living body contact layer is preferably 1 μm or more and 5 mm or less, and more preferably 2 μm or more and 3 mm or less. The thinner the living body contact layer, the lower the adhesive force, but the flexibility improves, and the weight becomes light and the compliance to the skin becomes good. The thickness of the living body contact layer can be selected in consideration of the adhesiveness or the texture to the skin.

[0208] In addition, in the living body contact layer of the present application, as with the previous living body contact layer (for example, the living body contact layer described in Japanese Patent Application Publication No. 2004-033468), in order to prevent the living body contact layer from peeling from the living body during use, an adhesive film can also be provided separately on the living body contact layer. In the case where the adhesive film is provided separately, the adhesive film can be formed using an adhesive film material of an acrylic type, a polyurethane type, a silicone type, or the like, and in particular, the silicone type is preferable because the oxygen permeability is high, the skin can breathe in the state where it is attached, the water repellency is also high, the decrease in the adhesiveness due to sweat is small, and further, the irritation to the skin is low. Furthermore, in the living body contact layer of the present application, as described above, peeling from the living body can be prevented by adding an adhesion-imparting agent to the living body contact layer, or by using a resin having good adhesion to the living body, and therefore, it is not necessarily required to provide the aforementioned separately provided adhesive film.

[0209] There is no particular limitation on the wiring of the sensor device or other members with respect to the living body contact layer when the living body electrode of the present application is used in a wearable device, and for example, the one described in Japanese Patent Application Publication No. 2004-033468 can be applied.

[0210] As described above, if the biological contact layer is the biological contact layer of the present application, since the biological contact layer containing the hardened product of the biological contact layer composition of the present application is included, a biological contact layer excellent in conductivity and biocompatibility, light in weight, capable of being manufactured at low cost, capable of preventing a large decrease in conductivity regardless of being wetted with water or dried, capable of rapidly collecting a signal after being attached to the skin, and incapable of causing skin residue can be produced. The biological contact layer of the present application can exhibit excellent conductivity, and thus can efficiently transmit an electrical signal from a living body such as the skin to a device. In addition, since the biological contact layer can exhibit excellent biocompatibility, even if it is worn on the skin for a long time, an allergy can be prevented. In addition, the biological contact layer of the present application can further improve conductivity by adding metal powder. In addition, by combining a resin having adhesiveness and stretchability in the biological contact layer of the present application, a biological contact layer particularly high in adhesiveness and high in stretchability can be produced. Furthermore, by adding an additive or the like to the biological contact layer, the stretchability or adhesiveness of the biological contact layer to the skin can be improved. In addition, the biological contact layer can adjust the stretchability or adhesiveness by appropriately adjusting the kind or amount of the deep eutectic liquid, the composition of the binder (A), or the amount of the conductive particles (B) of the present application, and the thickness of the biological contact layer. Thus, if the biological electrode of the present application is such a biological electrode, it is particularly suitable as a biological electrode used in a medical wearable device.

[0211] <Method for producing a biological electrode>

[0212] Further, the present application provides a method for producing a biological electrode, which is a method for producing a biological electrode having a conductive substrate and a biological contact layer formed on the conductive substrate, by coating the biological electrode composition described above on the conductive substrate and hardening it to form the biological contact layer.

[0213] Further, the present application provides a method for producing a biological electrode, which is a method for producing a biological electrode having a conductive substrate and a biological contact layer formed on the conductive substrate, by coating the biological electrode composition described above on a release substrate, hardening it, and transferring the patterned one to the conductive substrate to form the biological contact layer.

[0214] Further, the conductive substrate, the biological contact layer, and the like used in the method for producing a biological electrode of the present application can be the same as described above.

[0215] [Release substrate]

[0216] As the release substrate used in the method for producing a biological electrode of the present application, for example, a fluorine-based release film (SSIA or FSD5) of NIPPA (stock) can be used. The biological electrode composition of the present application is coated on such a release substrate and hardened.

[0217] The method for forming the organism contact layer on the conductive substrate is not particularly limited, and for example, dip coating, spray coating, spin coating, roll coating, flow coating, doctor blade coating, screen printing, flexographic printing, gravure printing, stencil printing, inkjet printing, or the like is preferable. In addition to these, whole surface film formation using a comma coater or a slit coater, pattern printing using screen printing or stencil printing, or the like can be mentioned.

[0218] The method for curing the organism electrode composition is not particularly limited, and for example, it is preferable to cure by either heat or light, or both. In addition, an acid- or base-generating catalyst can be added to the organism electrode composition described above, whereby cross-linking reaction is induced to cure.

[0219] Further, the temperature at the time of heating is not particularly limited, and for example, it is preferable to be about 50 to 250°C, depending on the type of the deep eutectic liquid and the binder (A) contained in the organism electrode composition.

[0220] In addition, in the case of combining heating and light irradiation, heating and light irradiation can be performed simultaneously, heating can be performed after light irradiation, or light irradiation can be performed after heating. In addition, before heating after coating, air drying can be performed for the purpose of evaporating the solvent.

[0221] In the case of a whole surface film, after laminating using a release film, cutting into an arbitrary pattern using scissors or a cutter, peeling off one piece of the release film covering the organism contact layer, transferring and attaching to the conductive substrate, and peeling off the second piece of the release film, the organism contact layer can be formed.

[0222] In the case of pattern printing such as screen printing or stencil printing, since an arbitrary pattern can be printed, the organism contact layer can be transferred and attached to the conductive substrate to form the organism contact layer.

[0223] Before attaching the organism contact layer of the present application to the skin, the skin is wiped with a gauze, absorbent cotton, or nonwoven fabric, or the like, which contains water or alcohol, to remove the oily components on the skin and to make the skin wet, whereby the sensitivity of the organism signal can be improved. If the skin is dry, the release of ions from the skin cannot be performed. The preferable component contained in the absorbent cotton, nonwoven fabric, gauze, or the like is water, water-soluble alcohol such as water-containing ethanol, glycerol, ethylene glycol, diethylene glycol, or the like.

[0224] If the method for manufacturing the biological electrode of the present application is used, as described above, the biological electrode of the present application can be easily manufactured at low cost, has excellent conductivity and biocompatibility, is light in weight, can prevent a large decrease in conductivity whether wetted with water or dried, can be attached to the skin to rapidly collect signals, and does not cause skin residue.

[0225] Examples

[0226] Hereinafter, the present application will be specifically described using examples and comparative examples, but the present application is not limited to these. Also, "Me" represents a methyl group, and "Vi" represents a vinyl group.

[0227] [Deep Eutectic Solvent]

[0228] The hydrogen bond-donating compound and the hydrogen bond-accepting compound blended in the deep eutectic solvent of the examples are shown below.

[0229] Hydrogen bond-donating compound

[0230] Polyglycerol-modified polysiloxane: KF-6100 manufactured by Shin-Etsu Chemical Co., Ltd.

[0231] Polyglycerol: Polyglycerol #310 manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.

[0232] Polyglycerol #500

[0233] Polyglycerol #750

[0234] Hydrogen bond-accepting compound

[0235] Quaternary ammonium cation-containing monomer: choline chloride manufactured by Tokyo Chemical Industry Co., Ltd.

[0236] Anhydrous betaine

[0237] Also, the deep eutectic solvents 1 to 9 blended in the biological electrode composition of the examples were synthesized in the following manner.

[0238] In a reaction vessel, the hydrogen bond-donating compound and the hydrogen bond-accepting compound were mixed at a predetermined molar ratio and heated at 125°C in an oven for 3 to 6 hours. The deep eutectic solvents 1 to 9 thus synthesized are shown below. The obtained deep eutectic solvents 1 to 9 were all liquid at 25°C.

[0239] [Table 1]

[0240]

[0241] [Binder resin (A)]

[0242] The siloxane compounds 1 to 4 incorporated as a polysiloxane-based resin in the biocompatible electrode compositions of Examples and Comparative Examples are shown below. The viscosity was measured using a cone-plate viscometer manufactured by Brookfield Co. at a cone rotor R = 12 mm, a cone angle of 3°, and a rotation speed of 10 rpm.

[0243] (Siloxane compound 1)

[0244] A vinyl group-containing polydimethylsiloxane having a viscosity of 27,000 MPa-s in a 30% toluene solution, an alkenyl group content of 0.007 mol / 100 g, and a molecular chain end terminated with a SiMe2Vi group was used as the siloxane compound 1.

[0245] (Siloxane compound 2)

[0246] A 60% toluene solution of a polysiloxane (Me3SiO 0.5 units and SiO2 units (Me3SiO 0.5 units / SiO2 units = 0.8) of an MQ resin was used as the siloxane compound 2.

[0247] (Siloxane compound 3)

[0248] A solution composed of 40 parts by mass of a vinyl group-containing polydimethylsiloxane having a viscosity of 42,000 MPa-s in a 30% toluene solution, an alkenyl group content of 0.007 mol / 100 g, and a molecular chain end terminated with OH, 100 parts by mass of a 60% toluene solution of a polysiloxane (Me3SiO 0.5 units and SiO2 units (Me3SiO 0.5 units / SiO2 units = 0.8) of an MQ resin, and 26.7 parts by mass of toluene was refluxed while being heated for 4 hours, and then cooled to bond the polydimethylsiloxane to the MQ resin, which was used as the siloxane compound 3.

[0249] (Siloxane compound 4)

[0250] As the methyl hydrogen polysiloxane oil, KF-99 manufactured by Shin-Etsu Chemical Co. was used.

[0251] The acrylic-based polymer 1 incorporated as an acrylic resin in the biocompatible electrode compositions of Examples and Comparative Examples is shown below. In addition, the molecular weight (Mw) and the dispersity (Mw / Mn) of the obtained polymer were confirmed by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent. The measurement temperature at this time was 40°C.

[0252] Acrylic-based polymer 1

[0253] Mw = 655,000

[0254] Mw / Mn = 2.32

[0255] [Chemical 19]

[0256]

[0257] The repeating number in the formula indicates an average value.

[0258] The polyurethane resins 1 to 3 blended as the resin (B) in the living electrode compositions of Examples and Comparative Examples are shown below. In addition, the weight average molecular weight (Mw) and the polydispersity (Mw / Mn) were confirmed by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent. The measurement temperature at this time was 40°C.

[0259] [Chemical 20]

[0260]

[0261] The repeating number in the formula indicates an average value. l is 12, m is 100, and n is 110.

[0262] [Conductive particles (B)]

[0263] The conductive particles (B) blended in the living electrode compositions of Examples and Comparative Examples are shown below. Metal powder Silver powder: Silver flake, 10 μm in diameter, manufactured by Sigma-Aldrich Co.

[0264] Gold powder: Gold powder, 10 μm or less in diameter, manufactured by Sigma-Aldrich Co.

[0265] Tin powder: Tin powder, 45 μm or less in diameter, manufactured by Sigma-Aldrich Co.

[0266] Titanium powder: Titanium powder, 45 μm or less in diameter, manufactured by Sigma-Aldrich Co.

[0267] Copper powder: Copper powder, 45 μm or less in diameter, manufactured by Sigma-Aldrich Co.

[0268] Carbon black: DENKA BLACK Li-400, manufactured by Denka Co.

[0269] Multi-walled carbon nanotube: 110 to 170 nm in diameter and 5 to 9 μm in length, manufactured by Sigma-Aldrich Co.

[0270] [Cross-linking agent]

[0271] The cross-linking agent blended in the living electrode compositions of Examples and Comparative Examples is shown below.

[0272] [Chemical 21]

[0273]

[0274] [Organic solvent (E)]

[0275] The organic solvent (E) blended in the organism electrode composition of the examples and comparative examples is shown below.

[0276] EDE: diethylene glycol diethyl ether

[0277] BE: diethylene glycol butyl ether

[0278] Isopar G (manufactured by Exxon Mobil Corporation): isoparaffin

[0279] [Additive]

[0280] The platinum catalyst and the reaction controller blended as an additive in the organism electrode composition of the examples and comparative examples are shown below.

[0281] Platinum catalyst: CAT-PL-56 manufactured by Shinku Chemical Industry Co., Ltd.

[0282] Reaction controller: 1-ethynylcyclohexanol manufactured by Tokyo Chemical Industry Co., Ltd.

[0283] [Ionic material]

[0284] The ionic polymer 1 used in the comparative examples was synthesized as follows. A 30 mass% cyclopentanone solution of each monomer was put in a reaction vessel and mixed, the inside of the reaction vessel was cooled to -70°C under a nitrogen atmosphere, and reduced pressure degassing and nitrogen purging were repeated three times. After the temperature was raised to room temperature, azobisisobutyronitrile (AIBN) was added as a polymerization initiator in an amount of 0.01 mol with respect to 1 mol of the total monomers, and after the temperature was raised to 60°C, the reaction was performed for 15 hours. After the solvent was dried, the composition of the obtained polymer was confirmed by 1 H-NMR. In addition, the molecular weight (Mw) and the dispersity (Mw / Mn) of the obtained polymer were confirmed by gel permeation chromatography (GPC) using tetrahydrofuran (THF). The measurement temperature at this time was 40°C. The ionic polymer 1 thus synthesized is shown below.

[0285] Ionic polymer 1

[0286] Mw = 44,400

[0287] Mw / Mn = 1.94

[0288] [Chemical 22]

[0289]

[0290] The repeating number in the formula represents an average value.

[0291] [Examples 1 to 22, Comparative Examples 1 to 7]

[0292] A deep eutectic liquid, a binder resin, conductive particles, an organic solvent, an additive (a platinum catalyst, a reaction control agent, a crosslinking agent, etc.), and an ionic material were mixed in the compositions described in Tables 2 to 4 to prepare a bioelectrode composition (bioelectrode compositions 1 to 22, comparative bioelectrode compositions 1 to 7).

[0293] [Table 2]

[0294]

[0295]

[0296] [Table 3]

[0297]

[0298] [Table 4]

[0299]

[0300] (Preparation of a sample for evaluation of a biological signal)

[0301] On a thermoplastic polyurethane (TPU) film ST-604 of Bemis Corporation, a conductive paste Dotite FA-333 of Toray Fine Chemicals Co., Ltd. was applied by screen printing, and the applied film was baked in an oven set to 120°C for 10 minutes to print a keyhole-shaped conductive pattern including a circular portion having a diameter of 2 cm and a rectangular portion. The circular portion of the printed conductive pattern was overlaid with a bioelectrode composition described in Tables 2 to 4 applied by screen printing, and the applied film was air-dried at room temperature for 10 minutes, and then baked in an oven at 125°C for 10 minutes to evaporate the solvent and harden. By the hardening, a biocontact layer (Examples 1 to 22, Comparative Examples 1 to 7) as a hardened product of each bioelectrode composition was obtained.

[0302] Figure 3 is a schematic view of a printed bioelectrode prepared in the example. As shown in Figure 3 A plurality of bioelectrodes 1 were prepared on a thermoplastic polyurethane film 20. Each bioelectrode 1 included a keyhole-shaped conductive pattern 2 as a conductive substrate, and a biocontact layer 3 overlaid on a circular portion of the conductive pattern 2.

[0303] Then, as shown in Figure 4As shown, the thermoplastic polyurethane film 20 on which the living body electrode 1 was printed was cut, the double-sided tape 21 was attached, and three living body electrode samples 10 (samples for evaluation of biological signals) were produced for one living body electrode composition.

[0304] (Measurement of thickness of living body contact layer)

[0305] In each of the living body electrode samples produced as described above, the thickness of the living body contact layer was measured using a micrometer. The results are shown in Table 5.

[0306] (Measurement of biological signals)

[0307] The conductive wiring pattern of the living body electrode formed of the conductive paste was connected to NeXuslO MARKII (a multi-sensor physiological measurement system) manufactured by MindMedia, a Dutch company, using a conductive wire, and the positive electrode of the electrocardiograph was attached to the position of LA of the left forearm in Figure 5 , the negative electrode was attached to the position of RA of the right forearm, and the ground wire was attached to the position of G. Measurement of the electrocardiogram was started immediately after the attachment, and the initial potential of the electrocardiogram waveform composed of P, Q, R, S, and T waves and the baseline fluctuation of the electrocardiogram waveform were evaluated. The results are shown in Table 5. In addition, the electrode surface or the skin can be wiped with a gauze impregnated with a solution containing 70% ethanol and 30% water immediately before the attachment. Figure 6

[0308] [Criteria for determination of initial potential of ECG signal]

[0309] O O: The potential is -50000 μV or more and less than +50000 μV

[0310] O: The potential is -100000 μV or more and less than -50000 μV, or +50000 μV or more and less than +100000 μV

[0311] Δ: Less than -100000 μV, or +100000 μV or more

[0312] X: The initial electrocardiogram cannot be measured

[0313] [Criteria for determination of potential fluctuation of baseline of ECG signal]

[0314] O: In the measurement of the electrocardiogram for 10 minutes, the potential fluctuation is less than 20000 μV from the initial potential.

[0315] Δ: In the measurement of the electrocardiogram for 10 minutes, there is a potential fluctuation of 20000 μV or more and less than 50000 μV from the initial potential.

[0316] ​X: In the measurement of electrocardiogram for 10 minutes, there is a potential change of 50,000 μV or more from the initial potential.

[0317] [Table 5]

[0318]

[0319] As shown in Table 5, in Examples 1 to 22 in which the hardened product of the biological electrode composition 1 to 22 formed by blending the deep eutectic liquid of the present application having the specific structure described above, the binder resin (A), and the conductive particles (B) was formed into the biological contact layer, the biological signal (ECG signal) could be obtained immediately after being attached to the body.

[0320] On the other hand, the comparative biological electrode composition 1 of Comparative Example 1 contained the ionic polymer compound, the binder resin (A), and the conductive particles (B), but did not contain the deep eutectic liquid. As a result, the comparative biological electrode composition 1 of Comparative Example 1 did not obtain the biological signal from the initial measurement. It is considered that this is because the ionic polymer is a solid, and thus the ion conductivity is poorer than the deep eutectic liquid.

[0321] Further, the comparative biological electrode compositions 2 and 4 of Comparative Examples 2 and 4 contained the ionic polymer compound, the binder (A), the conductive particles (B), and the hydrogen bond-donating compound used in the Examples, but did not contain the hydrogen bond-accepting compound, and did not contain the deep eutectic liquid. As a result, although the biological signal could be obtained from the initial measurement, the potential change of the baseline of the ECG signal was large. It is considered that this is because the hydrogen bond-donating compound is well-adhered to the body, and thus the biological signal can be obtained from the initial measurement, but since the ion conductivity of the electrode is poor, a polarization voltage is generated between the body and the electrode, and thus the potential change is large.

[0322] Further, the comparative biological electrode compositions 3 and 5 of Comparative Examples 3 and 5 did not contain the ionic polymer compound, but the results did not greatly change with or without the ionic polymer compound. It is considered that the reason for this is that since the ion conductivity of the ionic polymer compound is poor, a polarization voltage is generated between the body and the electrode, and thus the potential change is large.

[0323] The comparative biological electrode compositions 6 and 7 of Comparative Examples 6 and 7 added choline chloride and anhydrous betaine as the ionic material, but since these are solids, water was used in order to disperse them. However, it is considered that if these are coated to form a film, they are precipitated as solids, and thus do not have ion conductivity, and the biological signal cannot be obtained.

[0324] As described above, the deep eutectic liquid according to the present application, the biological electrode composition using the same, the biological electrode using the aforementioned composition, and the manufacturing method of the biological electrode can rapidly obtain a stable biological signal. That is, the deep eutectic liquid according to the present application, the biological electrode composition using the same, the biological electrode using the aforementioned composition, and the manufacturing method of the biological electrode can provide a biological electrode composition and a biological electrode that can rapidly obtain a stable biological signal when attached to a living body.

[0325] The present specification includes the following aspects.

[0326] [1] A deep eutectic liquid which is a mixture of a hydrogen bond-donating compound and a hydrogen bond-accepting compound, characterized by:

[0327] The hydrogen bond-donating compound is a compound having a structure in which 2 to 100 monomer bonds having a hydroxyl group are bonded, represented by the following general formula (1), the hydrogen bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the following general formulae (2) to (6) or a quaternary phosphonium cation represented by the following general formula (7), and the deep eutectic liquid exists in a liquid form at 25°C,

[0328] [Chemical Formula 23]

[0329]

[0330] In the formula, X represents a single bond, or a linear, branched, or cyclic divalent hydrocarbon group having 1 to 30 carbons which can be substituted with a heteroatom and can have a heteroatom inserted, Y and Z represent a linear, branched, or cyclic divalent hydrocarbon group having 1 to 5 carbons which can be substituted with a heteroatom, A and B represent a hydrogen atom, a hydroxyl group, an amino group, a halogen atom, or an alkyl group which can be substituted with a heteroatom or an alkyl group substituted at the terminal with a siloxane, Y and Z can each be the same or different, A and B can each be the same or different, m is an integer value of 1 to 100, representing the repetition of a chemical structural unit, n is an integer value of 1 to 4, representing the repetition of a chemical structural unit, but satisfies 2 ≤ m × n ≤ 100,

[0331] [Chemical Formula 24]

[0332]

[0333] In the formula, R1 to R 12 is a linear, branched, or cyclic monovalent hydrocarbon group having 1 to 30 carbons which can be substituted with a heteroatom, can have a heteroatom inserted, and can be a zwitterion having an anionic portion, a hydrogen atom, a hydroxyl group, an amino group, a nitro group, or a halogen atom, R1 to R 12 Each can be the same or different.

[0334] [2] The deep eutectic liquid of [1], wherein the monomer having a hydroxyl group is glycerol.

[0335] [3] The deep eutectic liquid of [2], wherein the hydrogen bond-donating compound is a polyglycerol-modified polysiloxane represented by the following general formula (8) or (9),

[0336] [Chemical Formula 25]

[0337]

[0338] wherein R1' each independently, which can be the same as or different from each other, is a hydrogen atom, a linear or branched alkyl group having a carbon number of 1 to 50, or a phenyl group, can contain an ether group, and can be a polysiloxane chain represented by the general formula (10), R2' is a group having a polyglycerol structure represented by the general formula (8)-1 or the general formula (8)-2, R3' each independently, which can be the same as or different from each other, is the above R1' or the above R2', R4' each independently, which can be the same as or different from each other, is the above R1', the above R2, or an oxygen atom, when R4' is an oxygen atom, 2 R4' can be bonded to form an ether group and form a ring together with the silicon atom to which they are bonded, a' can be the same as or different from each other, and is 0 to 100, b' is 0 to 100, a' + b' is 0 to 200, but when b' is 0, at least one of R3' is the above R2', R5' is an alkylene group having a carbon number of 2 to 10 or an aralkylene group having a carbon number of 7 to 10, R6' and R7' are alkylene groups having a carbon number of 2 to 6, R7' can be an ether group, c' is 0 to 20, and d' is 2 to 20.

[0339] [4] A living body electrode composition, characterized by containing the deep eutectic liquid according to any one of [1] to [3].

[0340] [5] The living body electrode composition according to [4], wherein the living body electrode composition contains a binder (A).

[0341] [6] The living body electrode composition according to [5], wherein the binder (A) is one or more resins selected from the group consisting of a silicone resin, a urethane resin, and an acrylic resin.

[0342] [7] The living body electrode composition according to any one of [4] to [6], wherein the living body electrode composition contains an electrically conductive particle (B).

[0343] [8] The living body electrode composition according to [7], wherein the electrically conductive particle (B) contains one or more selected from the group consisting of a carbon powder, gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, molybdenum, ruthenium, and indium.

[0344] [9] The bioelectrode composition of [8], wherein the carbon powder is either or both of carbon black and carbon nanotube.

[0345]

[10] The bioelectrode composition of any one of [4] to [9], further comprising glycerin.

[0346]

[11] A bioelectrode having an electrically conductive substrate and a biocontact layer formed on the electrically conductive substrate, wherein the biocontact layer contains a hardened product of the bioelectrode composition of any one of [4] to

[10] .

[0347]

[12] The bioelectrode of

[11] , wherein the electrically conductive substrate comprises one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon.

[0348]

[13] A method for manufacturing a bioelectrode having an electrically conductive substrate and a biocontact layer formed on the electrically conductive substrate, wherein:

[0349] the biocontact layer is formed by applying the bioelectrode composition of any one of [4] to

[10] to the electrically conductive substrate and hardening it.

[0350]

[14] The method for manufacturing a bioelectrode of

[13] , wherein, as the electrically conductive substrate, an electrically conductive substrate comprising one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon is used.

[0351]

[15] A method for manufacturing a bioelectrode having an electrically conductive substrate and a biocontact layer formed on the electrically conductive substrate, wherein:

[0352] the biocontact layer is formed by applying the bioelectrode composition of any one of [4] to

[10] to a release substrate, hardening it, and transferring the patterned one to the electrically conductive substrate.

[0353] Further, the present application is not limited to the above-described embodiments. The above-described embodiments are illustrative, and technical solutions having substantially the same configuration as the technical idea recited in the claims of the present application and exerting the same effects are included in the technical scope of the present application.

[0354] Explanation of Reference Signs

[0355] 1: Bioelectrode

[0356] 2: Electrically conductive substrate (electrically conductive pattern)

[0357] 3: organism contact layer

[0358] 4: electrically conductive particles

[0359] 5: deep eutectic liquid

[0360] 6: resin

[0361] 7: organism

[0362] 10: organism electrode sample

[0363] 20: thermoplastic polyurethane film

[0364] 21: double-sided tape

[0365] LA: positive electrode attachment

[0366] RA: negative electrode attachment

[0367] G: ground attachment

Claims

1. A deep eutectic liquid which is a mixture of a hydrogen bond-donating compound and a hydrogen bond-accepting compound, characterized in that: the hydrogen bond-donating compound is a compound having a structure in which 2 to 100 monomers having a hydroxyl group are bonded, represented by the following general formula (1), the hydrogen bond-accepting compound is a compound containing a monomer having a quaternary ammonium cation represented by the following general formulae (2) to (6) or a quaternary phosphonium cation represented by the following general formula (7), and the deep eutectic liquid exists in a liquid form at 25°C, in the formula, X represents a single bond, or a 2-valent hydrocarbon group having a linear, branched, or cyclic structure having 1 to 30 carbons which can be substituted with a hetero atom and can have a hetero atom inserted, Y and Z represent a 2-valent hydrocarbon group having a linear, branched, or cyclic structure having 1 to 5 carbons which can be substituted with a hetero atom and can have a hetero atom inserted, A and B represent a hydrogen atom, a hydroxyl group, an amino group, a halogen atom, or an alkyl group which can be substituted with a hetero atom and can have a hetero atom inserted or an alkyl group which is substituted at a terminal with a siloxane, Y and Z can each be the same or different, A and B can each be the same or different, m is an integer of 1 to 100, and represents the repetition of a chemical structural unit, n is an integer of 1 to 4, and represents the repetition of a chemical structural unit, but satisfies 2 ≤ m x n ≤ 100, the monomer having a hydroxyl group is glycerol. wherein R1to R 12 is a linear, branched or cyclic monovalent hydrocarbon group having a carbon number of 1 to 30 which can also be substituted with heteroatoms, can also have heteroatoms inserted therein, and can also be a zwitterion having an anionic portion, a hydrogen atom, a hydroxyl group, an amino group, a nitro group, or a halogen atom, R1to R 12 may be the same or different.

2. The deep eutectic liquid of claim 1, wherein, the hydrogen bond-donating compound is a polyglycerol-modified polysiloxane represented by the following general formula (8) or (9), 3. The deep eutectic liquid of claim 2, wherein, in the formula, each of R1' is independently, the same or different from each other, a hydrogen atom, a linear or branched alkyl group having 1 to 50 carbons, or a phenyl group, can contain an ether group, and can be a polysiloxane chain represented by the following general formula (10), R2' is a group having a polyglycerol structure represented by the general formula (8)-1 or the general formula (8)-2, each of R3' is independently, the same or different from each other, R1' or R2', R4' is independently, the same or different from each other, R1', R2, or an oxygen atom, when R4' is an oxygen atom, 2 R4' can be bonded to form an ether group and form a ring together with the silicon atom to which they are bonded, a' can be the same or different, 0 to 100, b' is 0 to 100, a' + b' is 0 to 200, but when b' is 0, at least one of R3' is R2', R5' is an alkylene group having 2 to 10 carbons or an aralkylene group having 7 to 10 carbons, R6' and R7' are alkylene groups having 2 to 6 carbons, R7' can be an ether group, c' is 0 to 20, and d' is 2 to 20. The deep eutectic liquid according to any one of claims 1 to 3.

4. A biological electrode composition, comprising: a biological material; and a conductive material, wherein the biological material and the conductive material are in contact. The biological electrode composition contains a binder (A).

5. The bioelectrode composition of claim 4, wherein, The binder (A) is one or more resins selected from the group consisting of a silicone resin, a polyurethane resin, and a polyacrylic acid resin.

6. The bioelectrode composition of claim 5, wherein, The biological electrode composition contains an electroconductive particle (B).

7. The bioelectrode composition of claim 4, wherein, The electroconductive particle (B) contains one or more selected from the group consisting of a carbon powder, gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, molybdenum, ruthenium, and indium.

8. The bioelectrode composition of claim 7, wherein, The carbon powder is any one or both of carbon black and a carbon nanotube.

9. The bioelectrode composition of claim 8, wherein, The biological electrode composition further contains glycerol.

10. The bioelectrode composition of claim 4, wherein, ​ 11. A biological electrode having an electrically conductive substrate, and a biological contact layer formed on the electrically conductive substrate, characterized by: The organism contact layer contains a hardened product of the organism electrode composition according to claim 4.

12. The biological electrode of claim 11, wherein, The conductive substrate contains one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon.

13. A method for manufacturing a biological electrode, which is a method for manufacturing a biological electrode having a conductive substrate and an organism contact layer formed on the conductive substrate, characterized by: The organism contact layer is formed by applying the organism electrode composition according to claim 4 to the conductive substrate and hardening it.

14. The method for manufacturing a bioelectrode according to claim 13, wherein As the conductive substrate, a conductive substrate containing one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon is used.

15. A method for manufacturing a biological electrode, which is a method for manufacturing a biological electrode having a conductive substrate and an organism contact layer formed on the conductive substrate, characterized by: The organism contact layer is formed by applying the organism electrode composition according to claim 4 to the conductive substrate and hardening it. As the conductive substrate, a conductive substrate containing one or more selected from the group consisting of gold, silver, silver chloride, platinum, aluminum, magnesium, tin, tungsten, iron, copper, nickel, stainless steel, chromium, titanium, and carbon is used.

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