Flexible electrode for biosignal measurement and manufacturing method therefor

Abstract

The present invention relates to a flexible electrode for biosignal measurement and a manufacturing method therefor. The electrode comprises: a flexible conductive sheet; and a flexible metal nanoparticle structure sheet on the conductive sheet, in which metal particles having a first size and metal particles having a second size are arranged so that a current flows in a direction perpendicular to the conductive sheet.

Description

Flexible electrode for measuring biosignals and method for manufacturing the same

[0001] The present invention relates to a flexible electrode for measuring biosignals and a method for manufacturing the same.

[0002] Electromyography is a test that measures and records electrical signals generated in skeletal muscles. It can be used to diagnose peripheral nerve damage, muscle disease, and central nervous system disease, and to determine the extent of damage.

[0003] Electromyography (EMG) is a test that analyzes electrical signals generated by the subject's muscle movements by attaching electrodes to the skin. The electrodes may include a conductive layer and a substrate to analyze the biosignals generated by the subject's muscle movements.

[0004] Here, biosignals can refer to the values ​​of signals generated from the human body at the moment of measurement. Depending on the form of data collected, biosignals can be categorized into data with simple characteristic values, such as body temperature and blood pressure, and data with a linear structure that flows continuously, such as electrocardiograms and respiration.

[0005] The background technology of the invention has been prepared to facilitate a better understanding of the present invention. It should not be construed as an admission that the matters described in the background technology of the invention constitute prior art.

[0006] The conductive layer and substrate for analyzing biosignals may have a direction in which the current flows in the vertical direction and the vertical direction, which may reduce the efficiency of biosignal analysis.

[0007] The inventors of the present invention recognized that when analyzing a biosignal through an electrode, the direction of the current flows in a horizontal direction rather than a vertical direction, which reduces the efficiency of the biosignal analysis.

[0008] Accordingly, the problem to be solved by the present invention is to provide a flexible electrode for biosignal measurement and a method for manufacturing the same, which has high efficiency in biosignal analysis by allowing the current direction of the electrode to flow only vertically by adjusting the spacing of conductive nanoparticles.

[0009] The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

[0010] In order to solve the above-described problem, a flexible electrode for measuring a biosignal according to one embodiment of the present invention is provided. The electrode is configured to include a flexible conductive sheet and a flexible metal nanoparticle structure sheet in which metal particles of a first size and metal particles of a second size are arranged on the conductive sheet so that the direction of current flows in a direction perpendicular to the conductive sheet.

[0011] According to a feature of the present invention, the metal nanoparticle structure sheet may further include a flexible polymer sheet in which the metal particles are dispersed.

[0012] According to another feature of the present invention, the metal nanoparticle structure sheet may be formed with a unit mass ratio of 50 wt% of the metal particles of the first size, 10 wt% of the metal particles of the second size, and 40 wt% of the polymer sheet.

[0013] According to another feature of the present invention, the polymer sheet may be made of at least one of ecoflex, polydimethylsiloxane (PDMS), or polyurethane (PU).

[0014] According to another feature of the present invention, the metal particles of the first size may be metal particles having a diameter of 2 micrometers to 3.5 micrometers.

[0015] According to another feature of the present invention, the second size metal particle may be a metal particle having a diameter of 75 nanometers to 85 nanometers.

[0016] According to another feature of the present invention, the metal particles may be composed of silver, gold, platinum, iron, stainless steel or a mixture thereof.

[0017] According to another feature of the present invention, the metal nanoparticle structure sheet may have a resistance in a vertical direction relative to the conductive sheet that is lower than a resistance in a horizontal direction relative to the conductive sheet.

[0018] According to another feature of the present invention, the metal nanoparticle structure sheet is such that the metal particles of the first size are arranged spaced apart from each other, and the metal particles of the second size are arranged on at least one of the upper side or the lower side of the metal particles of the first size, so that the metal particles of the first size and the metal particles of the second size can be arranged alternately in a row.

[0019] In order to solve the above-described problem, a method for manufacturing a flexible electrode for measuring a biosignal according to another embodiment of the present invention is provided. It is configured to include a step of mixing a metal powder and a metal ink to produce a first mixture, a step of mixing the first mixture with a first polymer sheet to produce a second mixture, a step of heating the second mixture to produce a third mixture, a step of mixing the third mixture with a second polymer sheet to produce a fourth mixture, a step of applying the fourth mixture through spin coating, and a step of heating the applied fourth mixture to produce an electrode.

[0020] According to another feature of the present invention, the metal powder may be composed of a plurality of metal particles having a diameter of 2 to 3.5 micrometers.

[0021] According to another feature of the present invention, the metal ink may be composed of a plurality of metal particles having a diameter of 75 to 85 nanometers.

[0022] According to another feature of the present invention, the metal particles of the metal powder may be comprised of 50 wt%, the metal particles of the metal ink may be comprised of 10 wt%, and the polymer sheet may be comprised of 40 wt% in a unit mass ratio.

[0023] According to another feature of the present invention, the metal ink may include metal particles and a hydrophobic solvent.

[0024] According to another feature of the present invention, the step of heating the second mixture to produce the third mixture may be a step of evaporating the hydrophobic solvent through heating.

[0025] According to another feature of the present invention, the hydrophobic solvent may be at least one of methyl isobutyl ketone, propanol, butanol, pentanol, hexanol, ethylene glycol and propylene glycol.

[0026] According to another feature of the present invention, the first polymer sheet and the second polymer sheet may be made of at least one of ecoflex, polydimethylsiloxane (PDMS), or polyurethane (PU).

[0027] According to another feature of the present invention, the metal powder and the metal ink may include at least one metal particle selected from the group consisting of silver, gold, platinum, iron, stainless steel, or a mixture thereof.

[0028] The present invention can increase the efficiency of biosignal analysis of the electrode by forming the horizontal resistance of the electrode high and the vertical resistance low, thereby allowing the current of the electrode to flow vertically.

[0029] In addition, the present invention can reduce the frequency of sensor drift by making the current direction of the electrode flow vertically, thereby increasing the durability and recoverability of the electrode and ensuring repeatability.

[0030] In addition, the present invention can increase the SNR in continuous use of the electrode by analyzing a biosignal through a metal nanoparticle structure sheet on the electrode, thereby improving the efficiency of electromyography analysis.

[0031] The effects according to the present invention are not limited to those exemplified above, and more diverse effects are included in this specification.

[0032] FIG. 1 and FIG. 2 illustrate the configuration of a flexible electrode for measuring biosignals according to an embodiment of the present invention.

[0033] FIG. 3 illustrates an exemplary process for manufacturing a flexible electrode for measuring biosignals according to various embodiments of the present invention.

[0034] FIG. 4 illustrates the results of current increase according to voltage increase in the horizontal and vertical directions of a flexible electrode for biosignal measurement according to another embodiment of the present invention.

[0035] FIG. 5 illustrates the results of the frequency of sensor drift occurrence of a flexible electrode for biosignal measurement according to another embodiment of the present invention.

[0036] FIG. 6 illustrates the results of SNR according to the frequency of use of a flexible electrode for measuring biosignals according to another embodiment of the present invention.

[0037] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. In connection with the description of the drawings, similar reference numerals may be used for similar components.

[0038] In this document, the expressions "has," "may have," "includes," or "may include" indicate the presence of a feature (e.g., a number, function, operation, or component such as a part), but do not exclude the presence of additional features.

[0039] In this document, the expressions "A or B," "at least one of A and / or B," or "one or more of A or / and B" can include all possible combinations of the listed items. For example, "A or B," "at least one of A and B," or "at least one of A or B" can all refer to cases where (1) at least one A is included, (2) at least one B is included, or (3) at least one A and at least one B are included.

[0040] The terms "first," "second," "first," or "second," as used herein, may describe various components, regardless of order and / or importance, and are only used to distinguish one component from another, without limiting the components. For example, a first user device and a second user device may represent different user devices, regardless of order or importance. For example, without departing from the scope of the rights set forth in this document, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

[0041] When it is said that a component (e.g., a first component) is "(operatively or communicatively) coupled with / to" or "connected to" another component (e.g., a second component), it should be understood that the component is directly coupled to the other component, or can be connected via another component (e.g., a third component). Conversely, when it is said that a component (e.g., a first component) is "directly coupled to" or "directly connected to" another component (e.g., a second component), it should be understood that no other component (e.g., a third component) exists between the first component and the other component.

[0042] The expression "configured to" as used herein can be used interchangeably with, for example, "suitable for," "having the capacity to," "designed to," "adapted to," "made to," or "capable of." The term "configured to" does not necessarily mean something is "specifically designed to" in hardware. Instead, in some contexts, the expression "a device configured to" can mean that the device, together with other devices or components, is "capable of." For example, the phrase "a processor configured (or set) to perform A, B, and C" may mean a dedicated processor (e.g., an embedded processor) for performing those operations, or a general-purpose processor (e.g., a CPU or application processor) that can perform those operations by executing one or more software programs stored in a memory device.

[0043] The terms used in this document are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include the plural expression unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this document. Terms defined in general dictionaries among the terms used in this document may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this document. In some cases, even if a term is defined in this document, it cannot be interpreted to exclude the embodiments of this document.

[0044] The individual features of the various embodiments of the present invention can be partially or wholly combined or combined with each other, and as can be fully understood by those skilled in the art, various technical connections and operations are possible, and each embodiment can be implemented independently of each other or can be implemented together in a related relationship.

[0045] For clarity in the interpretation of this specification, the terms used in this specification are defined below.

[0046] FIG. 1 and FIG. 2 illustrate the configuration of a flexible electrode for measuring biosignals according to an embodiment of the present invention.

[0047] Referring to FIG. 1, a flexible electrode (1000) for measuring biosignals includes a conductive sheet (100) and a metal nanoparticle structure sheet (200).

[0048] A flexible electrode (1000) for measuring biosignals can be attached to the skin of a subject and transmit an electrical signal to measure the subject's electromyography. At this time, the flexible electrode (1000) for measuring biosignals can be configured with flexible characteristics so as to be attached to the skin of the subject. Here, the flexible electrode (1000) for measuring biosignals can be configured with a material having excellent biocompatibility. In addition, the flexible electrode (1000) for measuring biosignals can be configured with a conductive sheet (100) which is a flexible substrate having conductivity and a metal nanoparticle structure sheet (200) which can control the direction of the flow of current.

[0049] The conductive sheet (100) may be made of a flexible material that can be conductive. At this time, the conductive sheet (100) may be composed of one of a polyimide (PI) substrate, a polyethylene terephthalate (PET) substrate, a polyethylene naphthalate (PEN) substrate, etc. Here, the conductive sheet (100) may be composed of a composite substrate in which a wiring portion and a light source portion are separated as a stretchable substrate technology. At this time, when the substrate of the conductive sheet (100) is deformed, only the wiring portion may be deformed, and the light source portion may not be deformed.

[0050] As another example, the conductive sheet (100) may be made of a hydrogel. In this case, the conductive sheet (100) may be conductive by using water through the hydrogel.

[0051] However, the conductive sheet (100) is not limited to the above materials, and may be made of any sheet or material having conductive and flexible properties.

[0052] The metal nanoparticle structure sheet (200) may be configured as a flexible sheet capable of controlling the flow of current. In this case, the metal nanoparticle structure sheet (200) may have a lower vertical electrical resistance than the horizontal electrical resistance. As a result, the metal nanoparticle structure sheet (200) can control the direction of current flow so that it flows vertically.

[0053] More specifically, referring to (a) of FIG. 2, the metal nanoparticle structure sheet (200) includes metal particles (210) and a polymer sheet (220).

[0054] The metal particle (210) can control the direction of the current of the metal particle structure sheet (200). At this time, the metal particle (210) can be composed of a metal with high body compatibility. For example, the metal particle (210) can be composed of gold, platinum, iron, stainless steel, or a mixture thereof, but can be composed of silver (Ag) more specifically.

[0055] The metal particles (210) include metal particles (211) of a first size and metal particles (212) of a second size. At this time, the metal particles (211) of the first size may be particles having a diameter of 2 to 3.5 micrometers. Here, the metal particles (212) of the second size may be metal particles having a diameter of 75 to 85 nanometers, and preferably, particles having a diameter of 80 nanometers.

[0056] At this time, the first size metal particles (211) and the second size metal particles (212) can be arranged alternately in a row.

[0057] Here, referring to (b) of FIG. 2, the first size metal particles (211) may be arranged to be spaced apart from each other in the X-axis and Y-axis directions. At this time, the resistance of the X-axis and Y-axis of the first size metal particles (211) may increase due to the distance spaced apart in the X-axis and Y-axis. Due to this, the metal nanoparticle structure sheet (200) may cause the current (240) flowing in the X-axis according to an increase in voltage to converge to 0.

[0058] Referring back to (a) of FIG. 2, the second-sized metal particles (212) may be arranged on either the upper or lower side of the first-sized metal particles (211). For example, the second-sized metal particles (212) may be arranged at least on either the upper or lower side of the X-axis of the first-sized metal particles (211). At this time, the first-sized metal particles (211) and the second-sized metal particles (212) may be arranged alternately. Here, the metal nanoparticle structure sheet (200) may have a particle aggregation ratio relative to the area in the X-axis and Y-axis lower than a particle aggregation ratio relative to the area in the Z-axis. As a result, the metal nanoparticle structure sheet (200) may have an increase in the current (230) flowing in the Z-axis as the voltage increases.

[0059] Above, an example of the configuration of a flexible electrode for measuring biosignals has been described, and below, a method of producing a flexible electrode for measuring biosignals will be described.

[0060] Referring to FIG. 3, a method for producing a flexible electrode for measuring a biosignal is configured to produce a first mixture by mixing metal powder and metal ink (S310). At this time, the method for producing a flexible electrode for measuring a biosignal may produce the first mixture by mixing the metal powder and the metal ink so that the mass ratio is 5 and the mass ratio is 2. Here, the metal ink may include metal particles and a hydrophobic solvent. At this time, the metal ink may be configured so that the mass ratio of the metal particles is 1 and the mass ratio of the hydrophobic solvent is 1. Here, the hydrophobic solvent may be composed of a colorless and flammable organic solvent. For example, the hydrophobic solvent may be composed of one of methyl isobutyl ketone, propanol, butanol, pentanol, hexanol, ethylene glycol, and propylene glycol.

[0061] Next, a method for producing a flexible electrode for measuring a biosignal is configured to mix a first mixture and a first polymer sheet to produce a second mixture (S320). At this time, the method for producing a flexible electrode for measuring a biosignal may produce a second mixture by mixing the first mixture and the first polymer sheet so that the mass ratio is 7 and the mass ratio is 2. Here, the polymer sheet may be composed of a material that can be easily stretched due to its high elongation. For example, the polymer sheet may be composed of one of ecoflex, polydimethylsiloxane (PDMS), or polyurethane (PU), but may preferably be composed of ecoflex.

[0062] Next, the method for producing a flexible electrode for measuring a biosignal is configured to heat the second mixture to produce a third mixture (S330). At this time, the method for producing a flexible electrode for measuring a biosignal may heat the second mixture so that the hydrophobic solvent of the second mixture is removed. For example, the method for producing a flexible electrode for measuring a biosignal may heat the second mixture to 55°C. At this time, the method for producing a flexible electrode for measuring a biosignal may mix using a magnetic bead.

[0063] Next, the method for producing a flexible electrode for measuring a biosignal is configured to produce a fourth mixture by mixing the third mixture and the second polymer sheet (S340). At this time, the method for producing a flexible electrode for measuring a biosignal may produce a second mixture by mixing the third mixture so that the mass ratio is 8 and the mass ratio of the second polymer sheet is 2. Here, the method for producing a flexible electrode for measuring a biosignal may be configured such that the mass ratio of the fourth mixture is 50 wt% of metal powder, 10 wt% of metal ink, 20 wt% of the first polymer sheet, and 20 wt% of the second polymer sheet.

[0064] Next, the method for producing a flexible electrode for measuring a biosignal is configured to topcoat the fourth mixture through spin coating (S350). At this time, the method for producing a flexible electrode for measuring a biosignal can coat any liquid by rotating the fourth mixture. Here, the method for producing a flexible electrode for measuring a biosignal can be configured to coat at 500 RPM for 5 seconds, 2000 RPM for 30 seconds, and 500 RPM for 5 seconds.

[0065] Next, the method for producing a flexible electrode for measuring biosignals is configured to produce an electrode by heating the fourth mixture (S360). At this time, the method for producing a flexible electrode for measuring biosignals can be heated at 90°C for 1 hour or at 120°C for 1 hour.

[0066] In the above, the flexible electrode for measuring bio-signals is described as a flexible electrode for measuring electromyogram or EMG signals, but is not limited thereto, and in another embodiment of the present invention, the flexible electrode for measuring bio-signals may be an electrode for measuring ECG (electrocardiogram), EEG (electro encephalography), EOG (electrooculography), etc.

[0067] Above, an example of a method for producing a flexible electrode for measuring biosignals has been described, and below, a performance evaluation of a flexible electrode for measuring biosignals will be described.

[0068] FIG. 4 illustrates the results of current increase according to voltage increase in the horizontal and vertical directions of a flexible electrode for biosignal measurement according to another embodiment of the present invention.

[0069] At this time, referring to (a) of FIG. 4, the result of the current increase according to the voltage increase in the vertical direction of the flexible electrode for measuring a biosignal is shown. At this time, the graph of the current increase according to the voltage increase in the vertical direction of the flexible electrode for measuring a biosignal may be composed of the current (401) on the Y-axis and the voltage (402) on the X-axis. Here, the graph of the current increase according to the voltage increase in the vertical direction of the flexible electrode for measuring a biosignal can be seen that as the voltage (402) increases, the current (401) flowing vertically increases (403) in direct proportion.

[0070] Referring to (b) of FIG. 4, the results of the current increase according to the voltage increase in the horizontal direction of the flexible electrode for measuring a biosignal are illustrated. At this time, the graph of the current increase according to the voltage increase in the horizontal direction of the flexible electrode for measuring a biosignal may be configured with the current (404) on the Y-axis and the voltage (405) on the X-axis. Here, the graph of the current increase according to the voltage increase in the horizontal direction of the flexible electrode for measuring a biosignal can be seen that even if the voltage (405) increases, the current (406) converges to 0.

[0071] Fig. 5 illustrates the results of the frequency of occurrence of sensor drift of a flexible electrode for measuring a biosignal according to another embodiment of the present invention. At this time, the graph of the frequency of occurrence of sensor drift of a flexible electrode for measuring a biosignal may be configured with the Y-axis representing current (501) and the X-axis representing time (502). Here, the graph of the frequency of occurrence of sensor drift of a flexible electrode for measuring a biosignal may be lower than that of other electrodes. As a result, the flexible electrode for measuring a biosignal may have increased durability and recoverability and repeatability.

[0072] FIG. 6 illustrates the results of SNR according to the frequency of use of a flexible electrode for measuring biosignals according to one embodiment of the present invention.

[0073] Referring to (a) of Fig. 6, a graph of SNR according to the frequency of use of a flexible electrode for measuring a biosignal may be configured such that the Y-axis represents SNR (601) and the X-axis represents the number of uses (602). Here, a graph of SNR according to the frequency of use of an existing electrode may illustrate that SNR (604) decreases as the number of uses (605) increases.

[0074] Referring to (b) of Fig. 6, a graph of SNR according to the frequency of use of an existing electrode may be configured such that the Y-axis represents SNR (604) and the X-axis represents the number of uses (605). Here, the graph of SNR according to the frequency of use of an existing electrode may illustrate that as the number of uses (605) increases, the SNR (604) decreases (606).

[0075] Accordingly, the present invention can increase the SNR in continuous use of the electrode by analyzing the biosignal by applying electrical stimulation to the electrode through a metal nanoparticle structure sheet, thereby improving the efficiency of electromyography analysis.

[0076] [National Research and Development Project Supporting This Invention]

[0077] [Project ID] 1415179021

[0078] [Assignment Number] 20015793

[0079] Ministry of Trade, Industry and Energy

[0080] [Name of Project Management (Specialist) Agency] Korea Industrial Technology Evaluation and Planning Institute

[0081] [Research Project Name] Nano-Convergence Innovation Product Technology Development Project

[0082] [Research Project Title] A Flexible and Stretchable Nanomaterial-Based Sensor System for Measuring Multiple Biomarkers for Diagnosis and Monitoring of Sarcopenia

[0083] [Name of the project performing organization] Exosystems Co., Ltd.

[0084] [Research Period] April 1, 2021 - December 31, 2025

Claims

1. Flexible conductive sheet; and A flexible electrode for measuring biosignals, comprising a flexible metal nanoparticle structure sheet in which metal particles of a first size and metal particles of a second size are arranged on the conductive sheet so that the direction of current flows in a direction perpendicular to the conductive sheet.

2. In paragraph 1, The above metal nanoparticle structure sheet, A flexible electrode for measuring biosignals, further comprising a flexible polymer sheet having the metal particles dispersed therein.

3. In paragraph 2, The above metal nanoparticle structure sheet, A flexible electrode for measuring a biosignal, wherein the first size metal particles are composed of 50 wt%, the second size metal particles are composed of 10 wt%, and the polymer sheet is composed of 40 wt% in a unit mass ratio.

4. In paragraph 2, The above polymer sheet, A flexible electrode for measuring biosignals, comprising at least one of ecoflex, polydimethylsiloxane (PDMS), or polyurethane (PU).

5. In paragraph 1, The metal particles of the first size are, A flexible electrode for measuring biosignals, which is a metal particle with a diameter of 2 micrometers to 3.5 micrometers.

6. In paragraph 1, The above second size metal particles are, A flexible electrode for biosignal measurement, comprising metal particles having a diameter of 75 to 85 nanometers.

7. In paragraph 1, The above metal particles are, A flexible electrode for measuring biosignals, made of silver, gold, platinum, iron, stainless steel or a mixture thereof.

8. In paragraph 1, The above metal nanoparticle structure sheet, A flexible electrode for measuring biosignals, wherein the resistance in the vertical direction with respect to the conductive sheet is lower than the resistance in the horizontal direction with respect to the conductive sheet.

9. In paragraph 1, The above metal nanoparticle structure sheet, The above first size metal particles are arranged spaced apart from each other, The metal particles of the second size are arranged on at least one of the upper or lower sides of the metal particles of the first size, A flexible electrode for measuring biosignals, wherein metal particles of the first size and metal particles of the second size are alternately arranged in a row.

10. A step of mixing metal powder and metal ink to produce a first mixture; A step of mixing the first mixture and the first polymer sheet to produce a second mixture; A step of heating the second mixture to produce a third mixture; A step of mixing the third mixture and the second polymer sheet to produce a fourth mixture; A step of applying the fourth mixture through spin coating; and A method for producing a flexible electrode for measuring a biosignal, comprising: a step of heating the applied fourth mixture to produce an electrode.

11. In paragraph 10, The above metal powder, A method for producing a flexible electrode for measuring biosignals, the flexible electrode comprising a plurality of metal particles having a diameter of 2 to 3.5 micrometers.

12. In paragraph 10, The above metal ink, A method for producing a flexible electrode for measuring biosignals, the flexible electrode comprising a plurality of metal particles having a diameter of 75 to 85 nanometers.

13. In paragraph 10, A method for producing a flexible electrode for measuring a biosignal, wherein the metal particles of the metal powder are composed of 50 wt%, the metal particles of the metal ink are composed of 10 wt%, and the polymer sheet is composed of 40 wt% in a unit mass ratio.

14. In paragraph 10, The above metal ink, A method for producing a flexible electrode for measuring biosignals, comprising metal particles and a hydrophobic solvent.

15. In paragraph 10, The step of heating the second mixture to produce a third mixture is: A method for producing a flexible electrode for measuring biosignals, the method comprising the step of evaporating the hydrophobic solvent through heating.

16. In paragraph 15, The above hydrophobic solvent is, A method for producing a flexible electrode for measuring a biosignal, the flexible electrode comprising at least one of methyl isobutyl ketone, propanol, butanol, pentanol, hexanol, ethylene glycol and propylene glycol.

17. In paragraph 10, The first polymer sheet and the second polymer sheet, A method for producing a flexible electrode for measuring biosignals, comprising at least one of ecoflex, polydimethylsiloxane (PDMS), or polyurethane (PU).

18. In paragraph 10, The above metal powder and the above metal ink, A method for producing a flexible electrode for measuring biosignals, comprising particles of at least one metal selected from the group consisting of silver, gold, platinum, iron, stainless steel, or a mixture thereof.

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