JP2013144051A - Electrode for acquiring biological signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for acquiring a biological signal, that is inexpensive and capable of accurate acquisition of the biological signal.SOLUTION: An electrode for acquiring a biological signal includes an electrode material and an electroplate. As for the electrode material, an amino acid or an organic salt is dissolved to an electrolyte solution. The electroplate consists of an electrically conductive material, and comes in electrical contact with the electrode material. The electrode material impregnates a water absorbing member in contact with the electroplate or is hardened to a gel or solid state. The electroplate consists of a carbon material. The electrode is an electrode for measuring a brain wave.

Description

  The present technology relates to a biological signal acquisition electrode that contacts a biological surface and acquires a biological signal.

  A biological signal such as an electroencephalogram or an electrocardiogram is measured by an electrode in contact with the surface of a living body (animal including a human). This electrode (hereinafter referred to as a biological signal acquisition electrode) is composed of an electrode material made of a liquid electrolyte, a gel-like electrolyte, a solid electrolyte, etc. impregnated with a water-absorbing material, and an electrode plate that is in electrical contact with the electrode material What has a structure provided with the member called is common.

  The electric plate is a member that exchanges electric charges with the electrode material, and preferably has a stable impedance with respect to the frequency of the biological signal and hardly causes an oxidation-reduction reaction with the electrode material. . For example, the “biological electrode” disclosed in Patent Document 1 has a structure in which a conductive adhesive composition and a conductive terminal are joined, and the conductive terminal is coated with Ag / AgCl. Has been.

JP 2011-10725 A

  As described above, the biological signal acquisition electrode electrode plate is made of a material having a small impedance variation with respect to the frequency of the biological signal, thereby enabling accurate measurement of the biological signal. However, such a material, for example, a material such as a silver-silver chloride sintered body or platinum, is more expensive than a general conductive material.

  In view of the circumstances as described above, an object of the present technology is to provide a biological signal acquisition electrode that is low-cost and that can accurately acquire a biological signal.

In view of the circumstances as described above, the biosignal acquisition electrode according to an embodiment of the present technology includes an electrode material and an electric plate.
In the electrode material, an amino acid or an organic salt is dissolved in an electrolyte solution.
The electric plate is made of a conductive material and is in electrical contact with the electrode material.

  According to this configuration, the impedance with respect to the frequency of the biological signal is stabilized regardless of the material of the electric plate. Therefore, it is possible to use an electrode plate made of an inexpensive material, and it is possible to create a biosignal acquisition electrode that can accurately measure a biosignal at low cost.

  The electrode material may be impregnated in a water-absorbing member in contact with the electric plate, or may be solidified in a gel form or a solid form.

  According to this configuration, by bringing the electrode material into contact with the surface of the living body, it is possible to acquire a biological signal using the electric field contained in the electrode material.

  The electric plate may be made of a carbon material.

  A carbon material (glassy carbon, isotropic graphite, biocarbon, etc.) hardly causes an oxidation-reduction reaction with an electrode material, and an accurate measurement of a biological signal is possible. In the biosignal acquisition electrode according to the present technology, since the impedance is stable regardless of the material of the electric plate, an electric plate made of a carbon material can be used.

  The biological signal acquisition electrode may be an electroencephalogram measurement electrode.

  The electroencephalogram has a lower frequency than other biological signals (such as an electrocardiogram), but the impedance is likely to fluctuate in the low frequency band. The biosignal measurement electrode according to the present technology is also suitable for measuring an electroencephalogram because the impedance in the low frequency band is stable.

  The amino acid may be glycine.

  Glycine has the same degree of electronegativity between the carboxyl group and the amine group in the molecule, and when it is contained in the electrode material, the impedance can be sufficiently stabilized as compared with other amino acids.

  As described above, according to the present technology, it is possible to provide a biological signal acquisition electrode that is low-cost and that can accurately acquire a biological signal.

It is sectional drawing of the electrode for biosignal acquisition which concerns on embodiment of this technique. It is a perspective view of the biosignal acquisition electrode. It is a graph which shows the impedance with respect to the biosignal frequency by the electrode for biosignal acquisition which concerns on a comparison. It is a graph which shows the impedance with respect to the biosignal frequency by the electrode for biosignal acquisition (containing sodium citrate) concerning the embodiment of the present technology. It is a graph which shows the impedance with respect to the biological signal frequency by the biological signal acquisition electrode (glycine containing) which concerns on embodiment of this technique.

  A biosignal acquisition electrode according to an embodiment of the present technology will be described.

[Configuration of electrode for biosignal acquisition]
FIG. 1 is a cross-sectional view showing the configuration of the biosignal acquisition electrode 1, and FIG. 2 is a perspective view of the biosignal acquisition electrode 1. 2A is a view of the biosignal acquisition electrode 1 from one side, and FIG. 2B is a view of the biosignal acquisition electrode 1 from the opposite direction. As shown in these drawings, the biological signal acquisition electrode 1 includes a support member 11, an electrode material 12, an electric plate 13, a terminal 14, and a pressing ring 15.

  The support member 11 is made of a nonconductive material such as synthetic resin, and supports the electrode material 12, the electric plate 13, and the terminal 14. The shape of the support member 11 is not particularly limited, but can be a container shape. The support member 11 shown in FIG. 1 includes a first member 11 a and a second member 11 b, and has a structure in which the second member 11 b presses the electric plate 13 accommodated in the first member 11 a through a pressing ring 15.

  The electrode material 12 is obtained by dissolving at least one of an amino acid and an organic salt in an electrolyte solution and abuts on the electric plate 13. The electrode material 12 can be obtained by impregnating a water-absorbing member such as a sponge with a solution in which an amino acid or an organic salt is dissolved in an electrolytic solution, and the solution is solidified in a gel or solid state. It can also be.

  The electrolyte solution can be a commonly used electrolyte solution such as sodium chloride solution or potassium chloride solution. The amino acid dissolved in the electrolyte solution can be selected from glycine, leucine, tryptophan, etc., but glycine having the same electronegativity of the carboxyl group and the amine group in the amino acid has a more stable impedance, Is preferred.

  The organic salt dissolved in the electrolyte solution is an organic acid salt that is a salt of an organic acid or an organic base salt that is a salt of an organic base. Examples of the organic acid salt include sodium citrate, sodium malate, sodium salicylate, and sodium benzenesulfonate. In addition, the organic acid salt can be a salt of an organic acid and an organic base or an inorganic base having an acidic group such as a carboxyl group, a sulfone group, a hydroxyl group, a thiol group, and an enol group. The organic base salt can be a salt of an organic base having a basic group such as an amine group or an organic base such as a heterocyclic compound and an organic acid or an inorganic acid. A higher amino acid or organic salt concentration is preferable because the conductivity of the electrode material 12 is higher, but it may be several percent.

  The electric plate 13 is made of a conductive material and contacts the electrode material 12. Conventionally, an electrode plate for a biosignal acquisition electrode has been required to be made of a material whose impedance variation with respect to the frequency of the biosignal is small, such as a silver-silver chloride sintered body or platinum. However, in the present embodiment, various conductive materials can be used for the reasons described later. Specifically, the electric plate 13 is made of silver-silver chloride, isotropic graphite, glassy carbon, biocarbon (fir shell regenerated carbon) or the like prepared by plating (not a sintered body). it can. Among these, carbon materials such as isotropic graphite and glassy carbon are less likely to cause an oxidation-reduction reaction with the electrolyte contained in the electrode material 12 and are suitable as a material for the electric plate 13.

  The terminal 14 is a terminal that is electrically connected to the electric plate 13 and to which the wiring of the measuring device is connected. The terminal 14 only needs to have conductivity, and the material, shape, and the like are not particularly limited.

  The biosignal acquisition electrode 1 has the above-described configuration. The biosignal acquisition electrode 1 is connected to a measurement device such as an electroencephalograph or an electrocardiograph and is used in contact with the surface of the living body. The biosignal acquisition electrode 1 can be attached to, for example, a device attached to a living body or a pad attached to the living body and brought into contact with the surface of the living body.

[Operation of biosignal acquisition electrode]
The operation of the biosignal acquisition electrode 1 will be described.

  As described above, the biosignal acquisition electrode 1 according to the present embodiment uses an electrode material 12 in which an amino acid or an organic salt is dissolved in an electrolyte solution. Thereby, when the electrode material is a conventional electrode material (sodium chloride, potassium chloride, etc.), even if the electric plate 13 made of a material (carbon material, etc.) whose impedance varies according to the frequency of the biological signal is used, Impedance fluctuations can be prevented.

  For comparison, FIG. 3 shows the impedance of the biological signal acquisition electrode with respect to the signal frequency when the signal is measured by a conventional electrode material (sodium chloride solution) and a biological signal acquisition electrode having an electrode plate made of various materials. It is the shown graph. 3A and 3B are different in the scale of the vertical axis.

  As shown in this graph, in the case of an electric plate made of a silver-silver chloride sintered body (Ag-AgCl), it can be said that the impedance is flat in a wide frequency band and the impedance is stable with respect to the signal frequency. . However, in the case of an electric plate made of biocarbon, isotropic graphite, and glassy carbon, it can be seen that the impedance fluctuates according to the signal frequency, and the impedance increases particularly in a low frequency band.

  4 and 5 are graphs showing the impedance of the biological signal acquisition electrode with respect to the signal frequency when the electrode plate 13 is made of various materials in the biological signal acquisition electrode 1 according to the present embodiment. is there. FIG. 4 shows a case where a solution in which sodium citrate is dissolved in an electrolyte solution is used as the electrode material 12, and FIG. 5 is a case in which a solution in which glycine is dissolved in the electrolyte solution is used as the electrode material 12.

  As shown in FIGS. 4 and 5, when the electrode material 12 is formed by dissolving an amino acid or an organic salt in an electrolyte solution, it can be seen that the impedance is stable over a wide frequency band. That is, by using the biosignal acquisition electrode 1, it can be said that the impedance is stable with respect to the frequency of the biosignal, and an accurate biosignal can be measured.

  In particular, since the low frequency band (about 10 Hz or less) corresponds to the frequency of the electroencephalogram, the biological signal acquisition electrode 1 is particularly effective in the electroencephalogram measurement. In addition, the biological signal acquisition electrode 1 is also suitable for measuring biological signals having a wide frequency band.

The reason why the impedance of the biological signal acquisition electrode 1 is stabilized by dissolving the amino acid or organic salt in the electrolyte solution is considered to be because the amino acid or organic salt can exchange protons (H ⁺ ).

  As described above, since the biological signal acquisition electrode 1 according to the present embodiment has a stable impedance with respect to the frequency of the biological signal regardless of the material of the electrical plate 13, the electrical plate 13 is made of an inexpensive material. Is possible. Therefore, the biological signal acquisition electrode 1 according to the present embodiment can accurately acquire a biological signal at low cost.

  The present technology is not limited only to the above-described embodiments, and can be changed without departing from the gist of the present technology.

  In addition, this technique can also take the following structures.

(1)
An electrode material in which an amino acid or an organic salt is dissolved in an electrolyte solution;
An electrode for biosignal acquisition, comprising: an electroplate made of a conductive material and in electrical contact with the electrode material.

(2)
The biosignal acquisition electrode according to (1) above,
The electrode for biosignal acquisition, wherein the electrode material is impregnated in a water-absorbing member in contact with the electric plate, or is solidified in a gel or solid state.

(3)
The biosignal acquisition electrode according to (1) or (2) above,
The electrode plate is a biosignal acquisition electrode made of a carbon material.

(4)
The biological signal acquisition electrode according to any one of (1) to (3) above,
The biosignal acquisition electrode is an electroencephalogram measurement electrode.

(5)
The biosignal acquisition electrode according to any one of (1) to (4) above,
The amino acid is glycine.

DESCRIPTION OF SYMBOLS 1 ... Electrode for biological signal acquisition 12 ... Electrode material 13 ... Electroplate

Claims (5)

An electrode material in which an amino acid or an organic salt is dissolved in an electrolyte solution;
An electrode for biosignal acquisition, comprising: an electroplate made of a conductive material and in electrical contact with the electrode material. The biosignal acquisition electrode according to claim 1,
The electrode for biosignal acquisition, wherein the electrode material is impregnated in a water-absorbing member in contact with the electric plate, or is solidified in a gel or solid state. The biosignal acquisition electrode according to claim 1,
The electrode plate is a biosignal acquisition electrode made of a carbon material. The biosignal acquisition electrode according to claim 1,
The biosignal acquisition electrode is an electroencephalogram measurement electrode. The biosignal acquisition electrode according to claim 1,
The amino acid is glycine.

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