JP6567800B2 - Biological electrode - Google Patents

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-described object is a biological electrode having an electrode pad to be attached to a living body and a lead wire portion fixed at one end to the electrode pad, and the lead wire portion is a flat base material including the electrode portion at one end. And a plurality of layers including a shield layer, and the shield layer disposed on the upper surface of the substrate is electrically conductive with the conductive fine wire pattern to be grounded and the entire upper surface of the substrate. The conductive thin line pattern has a conductivity higher than that of the entire surface pattern, and the conductive thin line pattern in the electrode portion is two-dimensional. It is a mesh pattern consisting of an outer edge of a figure and a linear pattern that exists within the outer edge and is connected to the outer edge. A detection electrode for detecting a bioelectric signal is arranged on the lower surface of the electrode part, and is two-dimensional outside of the graphic Is achieved by the biological electrodes, characterized in that it comprises an outer edge of the detection electrode.

  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. (A)-(c) 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, (d)-(e) is the conductive fine wire which the biological electrode which concerns on embodiment has. It is a figure which shows the other example of a pattern. It is a disassembled perspective view which shows the structural example of the electrode pad part of the bioelectrode which concerns on embodiment. It is a figure for demonstrating the effect 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. Electrode B is an indifferent electrode and is grounded. 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 is formed on the lower surface of the base material 114 (the surface facing the body surface when the electrodes are mounted), for example, by printing. 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). In the present embodiment, the upper shield pattern 113 is provided on the substrate 114 side (electrode pattern 115 side), and is grounded on the conductive thin wire pattern 113A and the conductive thin wire pattern 113A, and covers the entire surface of the substrate 114. The pattern 113B is composed of two layers.

  Conventionally, the upper shield pattern 113 is a single layer and is generally formed so as to cover the entire surface of the substrate 114 with a conductive paste in which carbon and silver are blended. 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.

  In view of this, the inventor examined a configuration that improves the shielding performance without substantially increasing the amount of expensive metal having high conductivity. As a result, noise resistance is greatly improved by forming an independent fine line pattern with a highly conductive substance and covering the entire substrate with a layer of a conductive substance that is less conductive than the substance constituting the fine line pattern. The inventors have found that it can be improved and have reached the present invention. This is a combination of the thin conductive wire pattern 113A in FIG. 1 and the entire surface pattern 113B.

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.

  The conductive fine line pattern 113A forms a wiring for promptly grounding the electric charges that conduct the entire surface pattern 113B provided in the upper layer. In other words, the conductive thin wire pattern 113A is not originally intended to cover the entire surface of the base material 114 without a gap and to realize a shield function alone, and is formed in a small amount even when an expensive metal having high conductivity is used. Is possible. Specifically, the code unit 150 is formed by a single thin line, and the electrode unit 1141 having a larger area than the code unit 150 and on which the detection electrode 104 is formed also exists on the outer edge and the outer edge of the two-dimensional figure. However, it can be formed of a mesh pattern 1131A composed of a linear pattern 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. 3). 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.

  The conductive thin wire pattern 113A is connected to the ground terminal of the connector through the electrode pattern of the ground electrode B in order to quickly release (ground) the charge causing signal noise. In this embodiment, since it has a configuration that can be electrically connected to the connector only on the lower surface side of the base material 114, the conductive thin wire pattern 113A provided on the upper surface side of the base material 114 is provided on the lower surface side of the base material 114. The connection portions 120 and 121 for electrical connection with the electrode pattern 115 electrically connected to the connector are provided on the mesh pattern 1131A provided on the electrode portion 1141 of the electrode B and the electrode pattern 115 of the electrode B. ing. However, if the conductive thin wire pattern 113A can be directly electrically connected to the connector, the connecting portions 120 and 121 are not necessary, and are extended to a position where, for example, the proximal end 1132 on the connector side contacts the terminal of the connector. FIGS. 2D and 2E schematically show the conductive thin line pattern 113A in the case of not having the connecting portions 120 and 121 with respect to the configuration of five electrodes and four electrodes.

  In the example of FIG. 1, the conductive thin wire pattern 113 </ b> A is provided over substantially the entire base material 114. However, as described above, the noise superimposed on the measurement signal is dominated by the conductive adhesive gel 103 provided on the detection electrode 104. Therefore, the conductive fine line pattern 113A may be provided only in a route necessary for guiding the mesh pattern 1131A provided on each electrode portion 1141 to the ground terminal of the connector. In the example of FIG. 1, since the connection portions 120 and 121 are provided only for the electrode B among the four electrodes A to D, the grounding of the mesh pattern 1131A provided for the electrodes C and D is Realized by passing B. Therefore, the conductive thin wire pattern 113A is also required between the mesh-shaped pattern 1131A provided on the electrode portion 1141 of the electrodes C and D and the electrode A, and the cord portion 150 between the electrode A and the electrode B. However, the conductive fine line pattern 113A provided in the section from the mesh-shaped pattern 1131A of the electrode A to the closest end 1132 is not essential. On the other hand, when the connection parts 120 and 121 shown in FIG. 2E are unnecessary, in order to transfer charges from the mesh-shaped pattern 1131A provided in each electrode part 1141 to the closest end 1132, The conductive thin wire pattern 113A is also required between the electrode A and the nearest end 1132.

  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 fine line pattern 113A to the conductive fine line pattern 113A, thereby realizing quick charge removal. Further, since the conductive thin line pattern 113A that does not transmit X-rays is a thin line, it is difficult to get in the way in the X-ray image. Therefore, if the entire surface pattern 113B is composed of only a substance that transmits X-rays such as carbon, it is possible to perform X-ray imaging with the bioelectrode attached.

  FIG. 3 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.

FIG. 4 is a diagram showing the effect of the bioelectrode having the configuration shown in FIGS. 1 and 3.
In FIG. 1, a bioelectrode having a structure in which the entire surface pattern 113B is formed with a conductive paste in which carbon and silver are mixed at a ratio of 1: 1 without providing the conductive thin wire pattern 113A was prepared (comparative example). On the other hand, the conductive thin wire pattern 113A is silver paste (conductivity 2 × 10 ⁶ [S / m] at 20 ° C., electrical resistivity 5 × 10 ⁻⁷ [Ω · m]), and the entire surface pattern 113B is carbon paste (20 ° C. A bioelectrode having the configuration shown in FIG. 1 and having a conductivity of 5 × 10 ² [S / m] and an electrical resistivity of 2 × 10 ⁻³ [Ω · m]) was prepared (Example). In addition, the total amount of silver used is the same in the configuration of the comparative example and the configuration of the example.

Then, the electrode of the configuration of the comparative example is mounted on the right chest of the subject, the electrode of the configuration of the example is mounted on the left chest of the same subject, and the electrode pads 101 of both are simultaneously rubbed with a cloth while simultaneously 2ch Bipolar electrocardiogram was measured.
FIG. 4A shows an electrocardiogram acquired with the configuration of the comparative example, and FIG. 4B shows an electrocardiogram acquired with the configuration of the example. As is clear from the comparison of both figures, the configuration of the example shows almost no influence of static electricity generated by rubbing with a cloth, whereas the configuration of the comparative example is an electrocardiogram in which noise is greatly superimposed. You can see that

  As described above, according to the present embodiment, the shield layer in the disposable bioelectrode in which the electrode pad and the lead wire portion are integrally formed is formed from above the conductive thin wire pattern and the conductive thin wire pattern. While having a two-layer structure with the entire surface pattern formed so as to cover the entire base material, while making the conductivity of the conductive fine wire pattern higher than the conductivity of the entire surface pattern, while suppressing the amount of metal with high conductivity Noise resistance can be improved at low cost.

Claims (3)

A biological electrode having an electrode pad to be attached to a living body and a lead wire portion having one end fixed to the electrode pad,
The lead wire part is a laminated structure in which a plurality of layers are formed on a flat substrate including an electrode part at the one end,
The plurality of layers includes a shield layer;
The shield layer disposed on the upper surface of the base material includes a conductive fine line pattern to be grounded, and an overall pattern made of a conductive material formed so as to cover the entire upper surface of the base material from above the conductive fine line pattern. Have
The conductivity of the conductive thin wire pattern is higher than the conductivity of the entire surface pattern,
The conductive thin line pattern in the electrode part is a mesh pattern composed of 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,
On the lower surface of the electrode portion, a detection electrode for detecting a bioelectric signal is disposed,
The biological electrode according to claim 1, wherein an outer edge of the two-dimensional figure includes an outer edge of the detection electrode.   The bioelectrode according to claim 1, 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 or 2, wherein the entire surface pattern is formed from a non-metallic conductive material.