WO2020095396A1 - Electrode and signal measurement device - Google Patents

Abstract

An electrode according to an embodiment of the present invention is an electrode passed through and attached to the skull to acquire brain waves, wherein the electrode is provided with: a first electroconductive part having a columnar shape and including a curved surface in one end part thereof; a second electroconductive part spreading in the radial direction of the first electroconductive part, the second electroconductive part being joined to the first electroconductive part on the opposite side from the one-end part of the first electroconductive part; and an insulating part including a first portion for covering a side surface of the first electroconductive part and a second portion for covering the surface of the second electroconductive part on the side thereof on which the first electroconductive part is connected.

Description

Electrode and signal measuring device

The present invention relates to the structure of electrodes.

 Mainly, there are two ways to measure brain waves: one is to attach electrodes to the scalp and measure indirectly, and the other is to attach electrodes to the brain and measure directly. The indirect measurement method has a poor SN ratio of the EEG signal. Therefore, when it is necessary to obtain an electroencephalogram signal with a good SN ratio, a direct measurement method is used. In this case, the substrate holding the electrodes needs to be placed under the dura. An example of a direct measurement method is disclosed in Patent Document 1.

JP, 2016-67368, A

In this way, in the measurement method of attaching the electrode to the brain surface, in order to place the substrate holding the electrode under the dura, it is necessary to open a part of the skull and further open the dura. Therefore, the load on the animal (human, monkey, etc.) to be measured is large. Further, such an electrode needs to be periodically replaced due to the influence of the environment in which it is placed. Since it is necessary to open a part of the skull for each replacement, the load on the animal to be measured is further increased.

One of the objects of the present invention is to reduce the load on the animal to be measured while measuring the electroencephalogram with a strong signal strength.

According to an embodiment of the present invention, an electrode attached to penetrate a skull for acquiring an electroencephalogram, the electrode having a pillar shape and including a curved surface at one end, and the first conductive portion. Of the second conductive portion, the second conductive portion that is coupled on the side opposite to the one end portion and that extends in the radial direction of the first conductive portion, and the first portion and the second conductive portion that cover the side surface of the first conductive portion. An insulating part including a second part covering the surface on the side to which the first conductive part is coupled is provided.

The first conductive portion may have a columnar shape.

The surface of the first conductive portion may be gold.

The first portion may cover a side surface of the first conductive portion other than the one end portion.

The first part and the second part may be combined.

The second portion may extend to the outside of the second conductive portion.

There is provided a signal measuring device including a plurality of electrodes described above, a wiring connected to each of the plurality of electrodes, and a signal output device connected to the wiring.

The wiring may be connected to the second conductive portion.

According to one embodiment of the present invention, it is possible to reduce the burden on the animal to be measured while measuring the electroencephalogram with a strong signal strength.

It is a block diagram which shows the structure of the electroencephalogram analysis system in 1st Embodiment of this invention. It is a figure which shows the external appearance of the electrode in 1st Embodiment of this invention. It is a figure which shows the external appearance when the conductive part and the insulating part which comprise the electrode in 1st Embodiment of this invention are isolate | separated. It is an example when arrange | positioning the electrode in 1st Embodiment of this invention to a skull. It is sectional drawing of the electrode in 1st Embodiment of this invention. It is sectional drawing of the electrode in 2nd Embodiment of this invention. It is sectional drawing of the electrode in 3rd Embodiment of this invention. It is sectional drawing of the electrode in 4th Embodiment of this invention.

Hereinafter, an electroencephalogram analysis system according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiment described below is an example of the embodiment of the present invention, and the present invention is not construed as being limited to this embodiment. In other words, it is possible to apply known techniques to a plurality of embodiments described below, make modifications, and carry out in various modes.

<First Embodiment>
[1. Outline of EEG analysis system]
FIG. 1 is a block diagram showing the configuration of an electroencephalogram analysis system according to the first embodiment of the present invention. The electroencephalogram analysis system includes a signal measurement device 1000 and an analysis device 50. The signal measuring device 1000 includes a plurality of electrodes 10-1, 10-2, ..., 10-n and a signal output device 30. When the plurality of electrodes 10-1, 10-2, ..., 10-n are not particularly distinguished, these electrodes are collectively referred to simply as the electrode 10. In this example, the plurality of electrodes 10 is arranged in a hole formed in the skull and acquires an electroencephalogram signal. The plurality of electrodes 10 are connected to the connector 20 via wires 80 (see FIG. 4). The detailed structure of the electrode 10 will be described later.

The signal output device 30 is connected to the plurality of electrodes 10 via the connector 20 and receives the electroencephalogram signal acquired by the electrodes 10. The signal output device 30 associates the received electroencephalogram signal with the electrode 10 that has received the electroencephalogram signal and the information related to the reception time, and temporarily stores the electroencephalogram information. The electroencephalogram information is output to a device outside the signal output device 30. In this example, the electroencephalogram information is output to the analysis device 50. The analysis device 50 stores the brain wave information acquired from the signal output device 30 and executes various analysis processes using the brain wave information.

The signal output device 30 includes a control unit 310, a P / S conversion unit 320, a memory 330, a communication unit 340, and a connector 350. The signal output device 30 also includes a battery (not shown) for driving these components. The battery may be a rechargeable secondary battery or a replaceable primary battery.

The control unit 310 includes an arithmetic processing circuit such as a CPU corresponding to a computer.

The P / S (parallel / serial) converter 320 converts the electroencephalogram signals input in parallel from the connector 20 connected to the connector 350 in parallel to the number of electrodes 10 into serial (serial) data. Output.

The memory 330 stores various information. The information stored in the memory 330 includes a program executed by the control unit 310 and brain wave information. The electroencephalogram information is information in which the electroencephalogram signal obtained for each electrode 10 is associated with time information as described above. That is, the electroencephalogram information allows the situation of the electroencephalogram signal at each time to be understood.

The communication unit 340 communicates with an external device such as the analysis device 50 under the control of the control unit 310. The communication method may be wireless communication or wired communication. When wired communication is adopted, the analysis device 50 may be connected to the communication unit 340 with the signal output device 30 removed from the connector 20.

The signal output device 30 stores the brain wave signal input via the connector 350 as the brain wave information in the memory 330, and outputs the brain wave information including the brain wave signal from the communication unit 340 in response to the request from the analysis device 50. , And is controlled by the control unit 310.

[2. Electrode configuration]
Next, the detailed structure of the electrode 10 will be described.

FIG. 2 is a diagram showing the external appearance of the electrode according to the first embodiment of the present invention. FIG. 3 is a diagram showing an external appearance when the conductive portion and the insulating portion that form the electrode according to the first embodiment of the present invention are separated. The electrode 10 includes a conductive portion 12 and an insulating portion 14. A part of the conductive portion 12 is covered with the insulating portion 14. In this example, the conductive portion 12 and the insulating portion 14 are removable.

The conductive portion 12 includes a shaft portion 122 (first conductive portion) and a head portion 124 (second conductive portion). In this example, the conductive portion 12 has a surface formed of at least gold. The inside of the conductive portion 12 may be formed of gold or another conductor. The surface of the conductive portion 12 may be a conductor other than gold, and may be a conductor having low corrosiveness, such as another noble metal or titanium, in order to reduce harm to the body.

The shaft portion 122 has a columnar shape between both ends. The shaft portion 122 has a curved surface shape in which a part of a sphere is cut off at one end 1225 thereof. Further, the shaft portion 122 has a head portion 124 coupled thereto at an end portion on the opposite side to the one end portion 1225. A surface of the head portion 124 that is coupled to the shaft portion 122 is referred to as a head lower surface 1243, and a surface opposite to the head lower surface 1243 is referred to as a head upper surface 1241. The head upper surface 1241 is a surface to which wirings described later are joined. The lower surface 1243 of the head is exposed outside the portion where the shaft 122 is coupled. In other words, the head portion 124 extends in the radial direction of the shaft portion 122 with respect to the shaft portion 122.

At least the outer surface of the insulating portion 14 is formed of an insulating member, and in this example, the whole is formed of an insulating member. In this example, the insulating member is made of a plastic material, but it may be made of an inorganic material or an organic material, and it is desirable that the insulating member is made of a material that is less harmful to living organisms.

The insulating portion 14 includes a tubular portion 142 (first portion) and an expanded portion 144 (second portion), and a through hole 146 penetrating the tubular portion 142 and the expanded portion 144 is arranged. When the insulating portion 14 is attached to the conductive portion 12, the shaft portion 122 is inserted into the through hole 146. That is, the diameter of the through hole 146 and the diameter of the shaft portion 112 are substantially the same. A surface of the expanded portion 144 to which the tubular portion 142 is coupled is referred to as an expanded portion lower surface 1443, and a surface opposite to the expanded portion lower surface 1443 is referred to as an expanded portion upper surface 1441. When the insulating portion 14 is attached to the conductive portion 12, the extension upper surface 1441 and the head lower surface 1243 are in contact with each other. In this example, the expanded portion upper surface 1441 is larger than the head lower surface 1243 and extends outward. Therefore, when the insulating part 14 is attached to the conductive part 12, the expansion part 144 covers the head lower surface 1243, and a part of the expansion part upper surface 1441 is exposed from the head 124.

When the insulating portion 14 is attached to the conductive portion 12 and the expanded portion upper surface 1441 and the head lower surface 1243 are in contact with each other, the tubular portion 142 is a side surface of the shaft portion 112 other than the one end portion 1225 of the shaft portion 122. And one end portion 1225 of the shaft portion 122 is exposed in a state of protruding from the lower end portion of the tubular portion 142. The above is the description of the structure of the electrode 10.

[3. Example of placement of electrodes on the skull]
Next, an example of disposing the electrode 10 on the skull will be described.

FIG. 4 shows an example of placing the electrode according to the first embodiment of the present invention on the skull. In FIG. 4, the structure of the insulating portion 14 is omitted. As shown in FIG. 4, the electrode 10 is arranged by inserting the electrode 10 into a hole 905 (see FIG. 5) formed in the skull 90. The diameter of this hole is greater than or equal to the outer diameter of the tubular portion 142 and less than the outer diameter of the expanded portion 144, and in this example, is substantially the same as the outer diameter of the tubular portion 142. Therefore, on the skull surface 910 side, the head portion 124 of the conductive portion 12 and the expansion portion 144 of the insulating portion 14 remain without being inserted. The electrode 10 is fixed to the skull 90 by covering a part of the head portion 124 and the entire expansion portion 144 with the fixing member 17. The fixing member 17 is an insulating material, for example, carboxylate cement. For the fixing member 17, it is desirable to use a material that is less harmful to the body.

The wiring 80 is joined to the head 124. In this example, the wiring 80 is joined to the head 124 by brazing using a brazing material 128. As a result, the head 124 and the wiring 80 are electrically connected. The wiring 80 and the head 124 may be joined by another welding technique such as pressure welding and fusion welding, or may be joined by another technique.

The wiring 80 is pulled out to the outside of the scalp 99 and connected to the connector 20. The surface of the wiring 80 is covered with an insulator except for the portion connected to the head portion 124 and the connector 20.

FIG. 5 is a sectional view of the electrode according to the first embodiment of the present invention. The sectional view shown in FIG. 5 shows a state in which the electrode 10 is inserted into the hole 905 of the skull 90. The conductive portion 12 is prevented from contacting the skull 90 by the insulating portion 14. Specifically, the tube portion 142 is arranged between the shaft portion 122 and the skull 90, and the expansion portion 144 is arranged between the head portion 124 and the skull. The skull 90 has conductivity due to moisture or the like, but is insulated from the conductive portion 12 by the insulating portion 14. Therefore, it is possible to prevent the conductive portion 12 of one electrode 10 from being electrically connected to the conductive portion 12 of another electrode 10 via the skull 90.

The electrode 10 is fixed to the skull 90 by the fixing member 17 arranged on the skull surface 910. In the example shown in FIG. 5, the fixing member 17 covers the exposed portion of the insulating portion 14, that is, the extension upper surface 1441 and the extension side surface 1448. Further, the fixing member 17 covers a part of the head side surface 1248 of the conductive portion 12. The fixing member 17 may cover the entire side surface 1248 of the head and further cover at least a part of the upper surface 1241 of the head, or may cover the entire upper surface 1241 of the head. When the entire top surface 1241 of the head is covered with the fixing member 17, the joint between the top surface 1241 of the head and the wiring 80 is also covered with the fixing member 17. When at least a part of the head top surface 1241 is covered with the fixing member 17, the conductive portion 12 is fixed to the skull 90 more strongly.

When the electrode 10 is fixed to the skull 90 by the fixing member 17, the electrode 10 is in a state of being pushed into the hole 905 of the skull 90 until the lower surface 1443 of the expanded portion comes into contact with the skull surface 910. In this state, the length of the shaft portion 122 is set so that the conductive portion 12 (the one end portion 1225 of the shaft portion 122) contacts the surface of the brain 95. Further, in this state, the length of the tubular portion 142 is set so that the lower end portion of the insulating portion 14 (the tubular portion 142) is located between the inner surface 920 of the skull 90 and the brain 95. However, it is desirable that the lower end portion of the tubular portion 142 be arranged at the position of the inner surface 920 of the skull 90, and it may be arranged at the position inside the hole 905.

Note that the distance between the inner surface 920 of the skull 90 and the brain 95 and the thickness of the skull 90 differ depending on the animal to be measured. Therefore, the size of each part of the electrode 10, such as the length of the shaft portion 122 and the length of the tubular portion 142, is appropriately set depending on the animal to be measured.

The part in contact with the brain 95 is the curved surface of the one end 1225 of the shaft 122. In this way, the portion that contacts the brain 95 has a curved surface shape that is convex outward, and does not have a corner portion (for example, a ridgeline) that protrudes outward, so that the electrode 10 is positioned relative to the brain 95. It becomes difficult to affect. For example, even if the force with which the shaft portion 122 is pressed against the brain 95 increases due to individual differences (size differences) of the animals to be measured, the brain 95 can be prevented from being damaged. The lower end of the cylindrical portion 142 may have a curved shape so that the outer peripheral portion does not have a corner. As a result, even if the lower end of the tubular portion 142 comes into contact with the brain 95, the same effect can be obtained.

Strictly speaking, the conductive portion 12 does not directly contact the brain 95, but contacts through the dura covering the brain 95. Since the one end portion 1225 of the shaft portion 122 has the above-described shape, the shaft portion 122 is hard enough to bring the dura and the brain 95 into contact with each other while reducing the load applied to the internal tissues such as the dura. The membrane can be deformed. As a result, even if the brain 95 is contacted via the dura, the electroencephalogram signal can be acquired with sufficient intensity via the conductive portion 12.

Further, as described above, the electrode 10 can be attached to the skull 90 for a long period of time by using a material having low biotoxicity for the electrode 10, so that the load on the animal to be measured is small. Even if the electrode 10 needs to be replaced, the electrode 10 inserted into the skull 90 can be replaced with another electrode 10, and the skull 90 and the dura are not required to be processed. The load on the target animal is small. Further, when maintenance of the signal output device 30 (main unit failure, charging of battery, replacement, etc.) is required, the signal output device 30 can be detached from the connector 20 and the signal output device 30 after maintenance can be attached to the connector 20 again. ..

<Second Embodiment>
In the above-described embodiment, the expansion part 144 is expanded to the outside of the head part 124, but the head part 124 may be expanded to the outside of the expansion part 144.

FIG. 6 is a sectional view of an electrode according to the second embodiment of the present invention. The electrode 10A shown in FIG. 6 includes an expansion portion 144A. The expansion portion 144A includes an expansion portion side surface 1448A arranged inside the head side surface 1248. Even with this structure, since the extension lower surface 1443A contacts the skull surface 910, the extension 144A prevents contact between the head lower surface 1243 and the skull surface 910, so that the head 124 and the skull 90 are not electrically connected. You can Further, the fixing member 17 is arranged between the head portion 124 and the skull 90 by expanding the fixing member 17 until it comes into contact with the expanded portion side surface 1448A, so that the head portion 124 and the skull 90 are not electrically connected to each other. can do.

As described above, the lower end portion of the tubular portion 142 may be present inside the hole 905 of the skull 90, and the shaft portion 122 and the skull 90 may not be bent so that the shaft portion 122 does not come into contact with the skull 90. It suffices that the insulating portion 14 exists between the two.

<Third Embodiment>
In the above-described embodiment, the head top surface 1241 has a planar shape, but may have another shape, or may have a curved surface shape obtained by cutting out a part of a sphere.

FIG. 7 is a sectional view of an electrode according to the third embodiment of the present invention. The electrode 10B shown in FIG. 7 includes a head 124B. The head 124B includes a head upper surface 1241B having a curved surface shape obtained by cutting out a part of a sphere. As described above, in the case where the peripheral portion is thin, a part of the fixing member 17 may cover the outer peripheral portion of the head portion 124B.

<Fourth Embodiment>
In the embodiment described above, the shaft portion 122 has a cylindrical shape, but it may have a step on the side surface. In this case, the side surface of the shaft portion 122 and the inner surface of the through hole 146 may have a portion that engages with each other.

FIG. 8 is a sectional view of an electrode according to the fourth embodiment of the present invention. The electrode 10C shown in FIG. 8 includes a shaft portion 122C and a tubular portion 142C. As shown in FIG. 8, the side surface of the shaft portion 122C has a male screw shape, and the inner surface of the through hole 146C has a female screw shape. As described above, the conductive portion 12C and the insulating portion 14C have a structure in which at least a portion where the conductive portion 12C and the insulating portion 14C are engaged with each other is at least partially formed, so that the conductive portion 12C is less likely to come off the insulating portion 14C.

<Modification>
Although one embodiment of the present invention has been described above, the above-described embodiments can be applied by being combined with or replaced with each other. Further, each of the above-described embodiments can be modified and implemented as follows. In the following modified example, an example applied to the first embodiment will be described, but it is also applied to other embodiments.

(1) In the first embodiment, the shaft portion 122 has a columnar shape between both ends, but it may not have a columnar shape, and may have another columnar shape. In the case of a shape other than a cylinder, the shape of a cross section perpendicular to the direction in which the pillar extends may be defined, and the direction extending outward from the center of gravity of this cross section may be defined as the radial direction. Note that the other columnar shape may be, for example, a cross-sectional shape other than the circular shape as in the first embodiment, and may be, for example, a rectangular shape, and forms an edge portion combined with a curved line and a straight line. It may have a shape.

The through hole 146 may also have an inner surface shape corresponding to the side surface shape of the shaft portion 122. The outer side surface of the tubular portion 142 may have various shapes like the side surface of the shaft portion 122, but it does not have to have the same shape as the side surface of the shaft portion 122. For example, the cylindrical portion of the shaft portion 122 may be formed in a prismatic shape, or the outer surface of the cylindrical portion 142 may be formed in a cylindrical side surface. Since the hole 905 of the skull 90 is mostly formed by a drill or the like, it is desirable that the outer surface of the tubular portion 142 has a cylindrical side surface.

(2) In the first embodiment, the one end portion 1225 of the shaft portion 122 has a curved surface shape obtained by cutting a part of a sphere, but may have another shape. For example, the shape does not have to be a part of the surface of the sphere as long as it has a shape including a curved surface portion that is convex outward in the portion that contacts the brain 95. Further, it is desirable that the portion that comes into contact with the brain 95 does not have a corner portion (for example, a ridgeline) that projects outward.

(3) In the first embodiment, the head portion 124 has a columnar shape with a low height, but it may have any shape as long as it has a portion that expands in the radial direction of the shaft portion 122. It may be. For example, the head upper surface 1241 and the head lower surface 1243 do not have to be circular, and may have, for example, a rectangular shape or a shape that forms an edge portion that is combined with a curved line and a straight line. In other words, when the head lower surface 1243 is viewed along the length direction of the shaft portion 122, the head lower surface 1243 may have a portion extending outside the shaft portion 122. Note that this point is the same in the relationship between the expanded portion 144 and the tubular portion 142 in the insulating portion 14.

(4) The insulating portion 14 may have elasticity. In this case, the diameter of the through hole 146 is made slightly smaller than the diameter of the shaft portion 122 in a state where the insulating portion 14 and the conductive portion 12 are separated. Then, when the conductive portion 12 is attached to the insulating portion 14, the shaft portion 122 may be inserted while expanding the diameter of the through hole 146 (while expanding the cylindrical portion 142 to the outside). With this configuration, the tubular portion 142 is pressed against the periphery of the shaft portion 122, the frictional force between the tubular portion 142 and the shaft portion 122 is increased, and the conductive portion 12 is unlikely to come off from the insulating portion 14.

10 ... Electrode, 12 ... Conductive part, 14 ... Insulating part, 17 ... Adhesive part, 20 ... Connector, 30 ... Signal output device, 50 ... Analysis device, 80 ... Wiring, 90 ... Skull, 95 ... Brain, 99 ... Scalp, 122 ... Shaft part, 124 ... Head part, 128 ... Brazing material, 142 ... Cylindrical part, 144 ... Expansion part, 146 ... Through hole, 310 ... Control part, 320 ... P / S conversion part, 330 ... Memory, 340 ... Communication Part, 350 ... Connector, 905 ... Hole, 910 ... Skull surface, 920 ... Inner surface, 1000 ... Signal measuring device, 1225 ... One end, 1241 ... Head upper surface, 1243 ... Head lower surface, 1248 ... Head side surface, 1441 ... Expansion part upper surface, 1443 ... Expansion part lower surface, 1448 ... Expansion part side surface

Claims (8)

An electrode that is attached through the skull to acquire brain waves,
A first conductive portion having a pillar shape and including a curved surface at one end,
A second conductive portion that is coupled on the opposite side of the one end portion of the first conductive portion and that extends in the radial direction of the first conductive portion;
An insulating portion including a first portion that covers a side surface of the first conductive portion and a second portion that covers a surface of the second conductive portion on a side to which the first conductive portion is coupled;
An electrode. The electrode according to claim 1, wherein the first conductive portion has a cylindrical shape. The electrode according to claim 1, wherein the surface of the first conductive portion is gold. The electrode according to claim 1, wherein the first portion covers a side surface of the first conductive portion other than the one end portion. The electrode according to claim 1, wherein the first portion and the second portion are joined together. The electrode according to claim 1, wherein the second portion extends to the outside of the second conductive portion. A plurality of electrodes according to any one of claims 1 to 6,
Wiring connected to each of the plurality of electrodes,
A signal output device connected to the wiring,
A signal measuring device provided with. The signal measuring device according to claim 7, wherein the wiring is connected to the second conductive portion.

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