JP2015123199A - Bioelectrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disposable bioelectrode having excellent noise resistance and being manufactured at a low cost.SOLUTION: The disposable bioelectrode includes a lead wire part that has a laminate structure configured by forming a plurality of layers on both surfaces of a flat backing material 114. The lead wire part includes a shield layer to be connected to a ground terminal. A resistivity of the shield layer is so controlled that a resistivity in a second section closer to the ground terminal than a first section is lower than a resistivity in the first section.

Description

  The present invention mainly relates to an electrode (bioelectrode) for obtaining a bioelectric signal, and more particularly, to a disposable bioelectrode.

  Conventionally, bioelectric signals typified by an electrocardiogram have been widely used as information useful for diagnosis. Depending on the purpose, the bioelectric signal may be acquired not only at rest but also during exercise and daily life. For example, electrocardiogram acquisition using a Holter electrocardiograph is a typical example of acquiring a bioelectric signal continuously for a long time during daily life.

  In order to acquire a bioelectric signal, a bioelectrode attached to the body surface is required. The bioelectrode is required to acquire a stable bioelectric signal with little noise over the acquisition period. Therefore, there are various types of bioelectrodes depending on the type of bioelectric signal to be acquired, the acquisition environment, the acquisition period, and the like.

  A bioelectrode premised on long-term use is desirably disposable (single use) from the viewpoint of saving hygiene and maintenance. Therefore, it has a configuration that can be manufactured at low cost, such as a configuration in which a wiring pattern is printed on a resin film and sandwiched with an insulator such as a foam sheet (Patent Document 1).

JP 2007-44208 A

  Since most of the bioelectric signal acquisition by the Holter electrocardiograph is performed while the subject is in a clothing state and not at rest, friction is constantly generated between the biological electrode and the clothing due to the body movement of the subject. As described above, since the disposable bioelectrode needs to be manufactured at a low cost, a coaxial induction cord with a built-in shield that is used in a bioelectrode premised on reuse cannot be used. Moreover, since it is mainly formed using a resin-based material, it is easily charged by static electricity due to friction. For this reason, the bioelectrode described in Patent Document 1 is provided with shield patterns (shield layers) made of a conductive material on the upper and lower surfaces for suppressing noise superimposed on the bioelectric signal due to static electricity.

  Conventionally, such a shield pattern is generally formed by applying (printing) a conductive paint containing carbon and silver, but antistatic (noise suppression) is not always sufficient, and further improvement Was desired.

  The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a biological electrode that is excellent in noise resistance and can be manufactured at low cost.

  The above-mentioned object is a disposable type comprising: an electrode pad to be attached to a living body; and a lead wire portion having a laminated structure in which one end is fixed to a plurality of electrode pads and a plurality of layers are formed on a flat substrate. The lead electrode has a shield layer connected to the ground terminal, and the resistivity of the shield layer is closer to the ground terminal than the first section than the resistivity in the first section. The bioelectrode is characterized in that the resistivity in the section 2 is controlled to be lower.

  With such a configuration, according to the present invention, it is possible to provide a biological electrode that has excellent noise resistance and can be manufactured at low cost.

It is a disassembled perspective view which shows the structural example of the lead wire part of the bioelectrode which concerns on embodiment of this invention. It is a figure for demonstrating the example of the mesh pattern of the conductive fine wire pattern which the biological electrode which concerns on embodiment has. It is a figure which shows typically the example of the resistivity control of the upper shield pattern in the bioelectrode which concerns on embodiment. It is a disassembled perspective view which shows the structural example of the electrode pad part of the bioelectrode which concerns on embodiment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an exploded perspective view showing a basic configuration example of a lead wire portion in which one end is fixed to an electrode pad and the other end is connected to a connector, among biological electrodes according to an embodiment of the present invention. In a disposable bioelectrode in which the electrode pad and the lead wire part are integrated, a laminated structure in which a plurality of layers having various functions are formed on a flat base material by printing or adhesion via an adhesive material layer Lead wire part. In the present embodiment, an example in which the present invention is applied to a biological electrode capable of measuring a 2-ch electrocardiogram using four electrodes will be described. However, the present invention is not limited to a bioelectrode for electrocardiogram measurement, but can also be applied to electrodes for measuring other bioelectric signals. The number of electrodes is not particularly limited, and can be applied to biological electrodes having a number of electrodes other than four electrodes such as one electrode, three electrodes, five electrodes, and seven electrodes. In the case of one electrode, it is used in combination with one or more other electrodes when measuring a bioelectric signal. One or more other electrodes may or may not have the structure described in this embodiment.

  The bioelectrode shown in FIG. 1 has four electrodes A to D. Each electrode basically has a common configuration, but the electrode A is arranged at a position close to an electrocardiograph (connector). On the other hand, the other electrodes B to D are provided from the outer edge of the electrode A through a cord portion 150 provided independently for each electrode. In addition, FIG. 1 has shown the structure of the layer provided by printing with respect to the base material 114 among the components of a bioelectrode. In the bioelectrode of this embodiment shown in FIG. 1, the electrode C is a common electrode.

  When the common electrode is not used, five electrodes (1ch +/−, 2ch +/−, indifferent electrode) are necessary for the bioelectrode for measuring the ECG waveform of 2ch. When five electrodes are used, as shown in Patent Document 1, each electrode has an independent cord portion.

  The flat substrate 114 is made of, for example, a PET film. An electrode pattern 115 made of, for example, printing is formed on the lower surface of the base material 114 (the surface facing the body surface when the electrodes are mounted). The electrode pattern 115 has a two-layer structure at the tip portion, and a circular detection electrode 104 and a short cord portion 1501 are provided in front of the detection electrode 104 in the lower layer portion. Moreover, about the electrode which provides the connection part 121 mentioned later, the connection part 121 is also provided in a lower layer. Since the lower layer portion includes a portion in contact with the conductive adhesive gel 103, the lower layer portion is formed from a mixture of silver chloride and silver which is not easily altered. On the other hand, the upper layer is made of silver, and the tip portion 1502 of the cord part 150 is arranged so as to overlap the cord part 1501 from the center of the lower detection electrode. This overlapping portion is provided in order to protect the upper end portion 1502 formed of silver with the lower cord portion 1501 formed of a mixture of silver chloride and silver.

  A resist pattern 116 for insulating the electrode pattern 115 is also provided on the lower surface of the electrode pattern 115 by printing. On the lower surface of the resist pattern 116, a lower shield pattern 117 made of a conductive material for removing static electricity is provided by printing. In the present embodiment, the lower shield pattern 117 is formed of a carbon paste. The cord portion 150 of the lower shield pattern 117 and the lower surface of the proximal end (connector side) from the electrode A, that is, the lowermost surface of the biological electrode (surface attached to the biological surface) have flexibility such as nonwoven fabric or foamed foam. The insulating sheet which has is adhere | attached with an adhesive material.

  An upper shield pattern 113 is formed on the upper surface of the base material 114 (the surface not attached to the living body). The present embodiment is characterized in that the resistivity (or conductivity) of the upper shield pattern 113 is controlled in at least two stages.

  Conventionally, the upper shield pattern 113 is formed to cover the entire surface of the substrate 114 with a conductive paste in which carbon and silver are blended. That is, the resistivity or conductivity of the upper shield pattern 113 is constant throughout. However, such a shield pattern (shield layer) does not necessarily have a sufficient shielding effect against static electricity generated by friction with clothes or noise propagated from the outside, and further reduces noise superimposed on the bioelectric signal to be measured. It was sought after.

  In order to enhance the effect of the shield, it is only necessary to increase the conductivity of the shield and promptly ground the charge causing noise. If a conductive paste in which carbon and silver are blended is used for forming the shield layer, the ratio of silver may be increased by decreasing the ratio of carbon. However, when the silver ratio is increased, the cost is greatly increased, which makes it unsuitable for a bioelectrode that is assumed to be disposable. As a result of examination by the inventors, there was room for improvement in noise resistance performance (shield performance) even when a conductive paste having a carbon to silver ratio of 1: 1 was used.

  Most of the noise is superimposed on the signal through the conductive adhesive gel 103 (see FIG. 3) for electrically connecting the body surface and the detection electrode 104, but noise due to static electricity is also superimposed on the code unit 150. Therefore, the total charge amount to be grounded increases from the electrode portion 1141 having the detection electrode 104 toward the ground terminal. Therefore, by controlling the resistivity of the upper shield pattern 113 in a plurality of steps according to the distance from the ground terminal so that the portion closest to the ground terminal has the lowest resistivity (or the highest conductivity), The present inventors have found that noise performance can be improved and have reached the present invention. In other words, by improving the movement speed of the charges according to the increase in the total amount of charges to be grounded, the time for which the charges stay on the path is shortened, and the smooth removal of electric charge is realized.

  Control of resistivity or conductivity can be performed by various methods. However, in a configuration in which wiring or a shield pattern is formed using printing, such as a disposable bioelectrode, the substance that forms the shield pattern is controlled. It would be realistic to control the resistivity or conductivity or to control the layer configuration. In the following, for ease of explanation and understanding, the description will be made on controlling the resistivity. However, the resistivity and the conductivity are inversely related and can be converted to each other, and therefore the conductivity may be controlled. Needless to say.

  In FIG. 1, the upper shield pattern 113 is added to the entire surface of the living body electrode by using a common material, and a thin line pattern independent of a highly conductive material is formed on the entire surface pattern in a section where the resistance value is decreased. An example in which two-step resistivity control is realized by the configuration formed in the lower layer of 113B is shown.

The thin conductive wire pattern 113A is formed from a material having high conductivity (electrical conductivity). Specifically, a substance having an electric conductivity at 20 ° C. of 1.43 × 10 ⁵ [S / m] or more (electric resistivity of 7 × 10 ⁻⁶ [Ω · m] or less) is preferable. Any of nonmetal, metal, and a mixture of nonmetal and metal may be used as long as this condition is satisfied, but it is preferable to contain a metal. Among metals, those having a conductivity at 20 ° C. of 1.0 × 10 ⁷ [S / m] or more (electric resistivity of 10 × 10 ⁻⁸ [Ω · m] or less) are preferable, and the conductivity at 20 ° C. is 2.5. It is more preferable that it is 10 ⁷ [S / m] or more (electric resistivity is 4 × 10 ⁻⁸ [Ω · m] or less). Examples of metals that satisfy this condition are silver (6.4 × 10 ⁷ [S / m], 1.55 × 10 ⁻⁸ [Ω · m]), copper (6.1 × 10 ⁷ [S / m], 1.64 ×) ^{10 -8 [Ω · m])} , aluminum ^{(3.8 × 10 7 [S /} m], 2.58 × 10 -8 [Ω · m]), gold ^{(3.0 × 10 7 [S /} m], 3.28 × 10 - ⁸ [Ω · m]).

  The metal may be an alloy such as an Fe—Cr alloy, an Fe—Ni—Mn alloy, or a Mo—Cr—Fe—Ni alloy. Further, a non-conductive component may be included. The specific substance to be used can be determined in consideration of the thin line pattern forming method, availability, cost, and the like. For example, when a pattern is formed by printing, silver or a substance containing silver can be preferably used from the balance between the availability of a pasty product and the conductivity.

  In the section in which the conductive thin wire pattern 113A is provided, the electric charge that conducts the entire surface pattern 113B provided in the upper layer can be transferred toward the ground terminal more quickly than the section in which only the entire surface pattern 113B is provided. In addition, the conductive thin wire pattern 113A is not originally intended to cover the entire surface of the base material 114 without any gap and realize a shield function alone, and is formed in a small amount even when an expensive metal having high conductivity is used. Is possible.

  The conductive thin line pattern 113A is configured by one thin line in the cord portion 150, but the electrode portion 1141 having a larger area than the cord portion 150 and in which the detection electrode 104 is formed captures charges more efficiently. In order to collect, it can be formed by the outer edge of the two-dimensional figure, and a mesh-like pattern 1131A composed of a linear pattern existing in the outer edge and connected to the outer edge. Here, the shape of the mesh is not particularly limited, but the outer edge of the mesh is a conductive adhesive gel 103 for electrically connecting the outer edge of the detection electrode 104 or the body surface and the detection electrode 104 (see FIG. 4). It is preferable to form so that the outer edge of this may be included. This is because most of the noise is superimposed on the signal through the conductive adhesive gel 103 portion.

  FIG. 1 shows a mesh shape in which three linear patterns connecting the outer edge of a circle and two points that divide the outer edge of the circle into six equal parts through the center of the circle are formed by thin lines of conductive material. However, a shape having a plurality of concentric circles as shown in FIG. 2 (a) and a linear pattern connecting the outer edges thereof, or a regular lattice shape as shown in FIG. 2 (b) may be used. On the other hand, the spiral pattern as shown in FIG. 2C does not correspond to the mesh pattern here. A spiral pattern is not preferable because an induced current is generated when noise comes from the outside. The mesh pattern 1131A preferably has a shape with little variation in the shortest distance from each position on the electrode portion 1141 of the substrate 114 to the fine line forming the mesh pattern 1131A. In other words, the pattern provided inside the outer edge preferably has an equal interval or a symmetrical shape.

  FIG. 3A schematically shows a path until the upper shield pattern 113 in the electrode structure shown in FIG. 1 is grounded. In the example of FIG. 1, the upper shield pattern 113 provided on the upper surface side of the base material 114 is the same as the upper shield pattern 113 of the electrode B because it has a configuration that can be electrically connected to the connector only on the lower surface side of the base material 114. It is grounded by being electrically connected through connection portions 120 and 121 provided in the electrode pattern 115. That is, the upper shield pattern 113B for the electrodes C and D is connected to the ground terminal via the upper shield pattern 113B between the electrodes A and B.

  Therefore, in the present embodiment, the path from the electrode A to the electrode B is (1) noise from the conductive adhesive gel 103 of the electrodes C and D, and (2) the path from the electrodes C and D to the electrode A. It is necessary to transfer electric charges related to (3) noise from the conductive adhesive gel 103 of the electrode A, and (4) noise in the path from the connector part to the electrode A. Therefore, the resistivity of the upper shield pattern 113 downstream (connector ground terminal side) from the position (electrode A) where charges related to noise from a plurality of paths flow is controlled to be lower than the resistivity upstream. . Specifically, a conductive thin wire pattern 113A is provided downstream from the electrode A, and the upper shield pattern 113 has a two-layer structure.

  The entire surface pattern 113B provided on the conductive thin line pattern 113A is formed so as to cover the entire surface of the base material 114 from above the conductive thin line pattern 113A. The entire surface pattern 113B is formed of a conductive material, but has lower conductivity than the material forming the conductive thin line pattern 113A. In order to provide a function of protecting the conductive thin wire pattern 113A from alteration such as oxidation and corrosion, the entire surface pattern 113B is also preferably formed of a material that is not easily oxidized or corroded. In the present embodiment, the entire pattern 113B is formed using a non-metallic carbon paste as a material that satisfies these conditions and can form a pattern by printing, but other materials including the use of metal may be used. It may be used.

  As described above, since the conductive fine line pattern 113A is a so-called wiring formed from a fine line, its area is much smaller than that of the base material 114. Therefore, the entire surface pattern 113B made of a conductive material provides a path for quickly moving charges existing at a position away from the conductive thin wire pattern 113A to the conductive thin wire pattern 113A, and only the entire surface pattern 113B is provided in the section where both are provided. Charge removal is realized more quickly than the section in which is provided.

  In addition to the above (1) to (4), (5) noise in the path from the electrode A to the electrode B, and (6) noise from the conductive adhesive gel 103 of the electrode B downstream from the electrode B Therefore, the resistivity of the electrode pattern 115 with respect to the ground electrode B may be further reduced.

  Unlike the example of FIG. 1, in the form in which each electrode is directly connected to the connector ground terminal (FIG. 3B), the portion downstream from the electrode portion may be configured to have a lower resistance than the electrode portion.

  Here, an example in which the resistivity is controlled by using the upper shield pattern 113 as a two-layer structure has been described, but a multilayer structure having three or more layers may be used, or the resistivity may be controlled by the width of the pattern. When the upper shield pattern 113 has a single layer structure, the width of the base material 114 can be configured to increase toward the downstream side. Even in the case of the two-layer structure, the resistivity can be controlled by similarly controlling the width of the layer that is not the entire surface pattern. Further, the resistivity may be controlled by controlling the thickness of the layer. For example, you may make it increase the frequency | count of application | coating of the conductive paste of the same composition as the area close | similar to a ground terminal.

  How many steps to control the resistivity, where to change the resistivity, and how to set the specific resistivity depends on the noise characteristics in the environment where the bioelectrode is used. It can be determined accordingly. However, it is preferable to perform control so that the resistance is lowered at the downstream side from the position where the charges to be grounded merge from the plurality of paths than at the upstream side. Further, when controlling the width of the pattern, the resistance may be smoothly reduced by gradually increasing the width.

  FIG. 4 is a diagram for explaining the configuration of the electrode pad 101 in the biological electrode of the present embodiment. An electrode pad is a part attached to the surface of a living body. A non-disposable bioelectrode generally has a structure in which an electrode pad and a lead wire (inductive cord) are separated from each other, but in the case of a disposable structure, the electrode pad and the lead wire have an integrated structure. .

  As shown in FIG. 1, the detection electrode 104 is formed at the tip of the electrode pattern 115. Of the electrode pads 101, the pad base material 106 that fixes the conductive adhesive gel 103 to the body surface diffuses moisture generated from the skin to improve the adhesion to the skin, and to the skin wrinkles caused by body movements, etc. Is made of a flexible moisture-permeable waterproof film so that it can be deformed following the movement. The thickness of the moisture permeable waterproof film that can be used as the pad substrate 106 is preferably 20 to 70 μm, more preferably 30 to 60 μm, particularly preferably 40 to 60 μm, and most preferably 45 to 55 μm.

  If the moisture permeable waterproof film is too thick, the effect of diffusing moisture from the skin cannot be obtained sufficiently, it becomes easy to peel off, and it causes rashes and stuffiness, which deteriorates the feeling of wearing. Furthermore, since flexibility (especially followability with respect to wrinkles on the surface of the skin) is reduced, the electrode is stiff and the wearing feeling is deteriorated, and it is easy to peel off. Furthermore, there is a problem that noise is easily superimposed on the bioelectric signal due to the decrease in flexibility.

  An adhesive is applied to the mounting surface of the pad base material 106, and an arc-shaped second separator 102 is provided on the outer edge of the mounting surface. The second separator is release paper, and the surface facing the first separator 109 that is the separator of the entire electrode pad 101 does not have adhesiveness. Therefore, the region where the second separator 102 exists on the mounting surface of the pad base 106 can be easily separated from the first separator 109.

  A hole 1061 corresponding to the electrode is provided in a substantially central portion of the pad base material 106. Since the electrodes A to D and the vicinity thereof in FIG. 1 are attached to the pad base material 106 by the sealing member 105, the insulating sheet 111 is not provided on the uppermost surface and the lowermost surface.

  A conductive adhesive gel 103 is provided on the lower surface of the electrode. The conductive adhesive gel 103 may be attached to the electrode by a conductive adhesive applied to the lower surface of the electrode, or the outer peripheral portion is fixed by the adhesive applied to the mounting surface of the pad base 106, May be in direct contact.

  The seal member 105 is made of, for example, the same moisture permeable waterproof film as the pad base material 106. The seal member 105 is provided to fix the electrode to the pad base material 106.

  When mounting the electrode pad 101, first, the electrode pad 101 is separated from the first separator 109 using the second separator 102. Then, while supporting the electrode pad 101 with the second separator 102, the electrode pad 101 is moved to the mounting site, and is attached to the body surface from the outer edge portion without the second separator. Then, while peeling off the second separator 102, the entire surface of the pad base 106 is brought into close contact with the body surface.

  As described above, according to this embodiment, the resistivity of the shield layer in the disposable bioelectrode in which the electrode pad and the lead wire portion are integrally formed is closer to the ground terminal than in the first section. By controlling so that it becomes lower than the 1st area in this area, noise-proof performance can be improved at low cost.

Claims (9)

An electrode pad attached to a living body;
A lead wire part having a laminated structure in which one end is fixed to the plurality of electrode pads and a plurality of layers are formed on a flat substrate, and a disposable bioelectrode,
The lead wire portion has a shield layer connected to a ground terminal;
The resistivity of the shield layer is controlled so that the resistivity in the second section closer to the ground terminal than the first section is lower than the resistivity in the first section. A living body electrode.   The first section of the shield layer has a single-layer structure, and the second section has a multilayer structure having a conductive thin wire pattern connected to the ground terminal in addition to the structure of the first section. The bioelectrode according to claim 1.   The bioelectrode according to claim 2, wherein the substance forming the first section is a conductive substance having a lower conductivity than the substance forming the conductive thin wire pattern.   A portion fixed to the electrode pad of the lead wire portion forms an electrode portion including a detection electrode for detecting a bioelectric signal, and a mesh-like pattern is formed when the conductive thin wire pattern is provided on the electrode portion The biological electrode according to claim 2 or 3, wherein   5. The biological electrode according to claim 4, wherein the mesh pattern is formed from an outer edge of a two-dimensional figure and a linear pattern that exists in the outer edge and is connected to the outer edge. The electrode pad is provided with a conductive adhesive gel for electrically connecting the detection electrode and the living body,
The biological electrode according to claim 5, wherein an outer edge of the two-dimensional figure is formed so as to include an outer edge of the conductive adhesive gel or the detection electrode.   The bioelectrode according to any one of claims 2 to 6, wherein the conductive thin wire pattern is formed of a substance containing at least one of gold, silver, and copper.   The bioelectrode according to claim 1, wherein in the second section, the shield layer is formed wider than the first section.   The bioelectrode according to claim 1, wherein the shield layer is formed thicker in the second section than in the first section.

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