JP2003204946A - Microminiature biological electrode used for measurement of neuro-activity or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microminiature biological electrode for measuring the neuro- activity or the like of a biological body, wherein the volume is small, burden to the biological body is small, the insulating property is high, and therefore, a stable measurement extending for a long period of time becomes possible. <P>SOLUTION: This microminiature biological electrode 10 has a pair of conductive bodies 13 and 14 made of a polymeric material having a through-hole in which a measurement object 18 is passed at the center, an inserting member 15 made of a non-conductive polymeric material, end surface members 16 and 17 which are provided on the external end surfaces of the conductive bodies, a cylindrical covering body 17 made of an insulating material which surrounds the outer periphery of them, and electric wires 21 and 22 for the measurement which are led to the outside from respective conductive bodies 13 and 14. In this case, the inserting member 15 electrically insulates the peripheries of the conductive bodies, and is inserted in a space between the conductive bodies. Then, a slit 26 which reaches the outer peripheral surface from the through-hole 19 is provided on all of the conductive bodies, the inserting member, the end surface members and the covering body for the microminiature biological electrode 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microminiature biological electrode for measuring a minute potential difference or a minute current in a nerve bundle of a living body. More specifically, the present invention relates to a biological electrode that can be used in a state of being embedded in a living body and can continue measurement for a long period of time without burdening the living body.

[0002]

2. Description of the Related Art Conventionally, when measuring the nerve activity of a living body, an electrode made of a metal material such as collagen or silver wire which is a biopolymer is brought into contact with the nerve bundle, and an insulated wire connected to the electrode is measured. It connects to the circuit and measures the minute electric current that flows through the nerve. These electrodes have been applied to peripheral nerves on the order of millimeters and sympathetic nerves on the heart and kidneys on the order of hundreds of micrometers to measure nerve activity. However, the visceral organs such as the adrenal gland, spleen, and digestive organs, or the sympathetic nerves distributed in skeletal muscle, skin, brain, spinal cord, and the like are extremely thin, 100 μm or less, and are easily mechanically damaged. Therefore, it is difficult to measure especially in the case of conscious animals that take free actions. In addition, since it is difficult to maintain the insulating property for a long time in the living body, the measurement can be continued only for a short period of about one week. Furthermore, since the signal to be measured is a minute signal of the microvolt level, reliable signal processing is difficult.

As a biological electrode for improving the reliability of signal processing, for example, there is a microelectrode described in Japanese Patent Laid-Open No. 2000-157669. This microelectrode is a microelectrode body including electrodes shown in FIGS. 10A to 10C and the like, so that signal processing with high S / N can be performed, and electrical contact is provided near the microelectrode body via a wiring portion. And a signal processing circuit body connected to. The publication discloses a clamp-type electrode 101 having a U-shaped configuration as shown in FIG. 10a, between which a contact is made through a nerve axon 100. Further nerve axon 1
Fork electrode (see 102 in FIG. 10b) and needle electrode (103 in FIG. 10c) adapted to be pierced at 00.
(See each) are disclosed.

[0004]

The clamp-type, fork-type, or needle-type microelectrode bodies described above can be applied only to thick nerve axons, and can be easily attached to and detached from nerve axons, but stable. There is a limit to how much neural activity can be measured. Further, since the measurement target is a fine nerve bundle or a living body, invasion of the nerve or the living body is likely to occur. Furthermore, it is difficult to maintain the insulation state for a long period of time, and it is difficult to stably attach a thin nerve for a long period of time. Especially, in order to elucidate the integrated regulatory function of the biological system performed by the brain and autonomic nervous system by measuring the autonomic nerve activity that governs the above-mentioned various organs, it is necessary to measure multiple points simultaneously and measure long-term changes. . An object of the present invention is to provide a microminiature biomedical electrode which has a small volume and therefore has a small burden on a living body and which can be multidimensionally measured. Further, it is a technical object of the present invention to provide a microminiature biomedical electrode having a high insulating property, which enables stable measurement for a long period of time.

[0005]

The microminiature biomedical electrode of the present invention (claim 1) comprises a pair of conductors made of a polymer material, each of which has a through hole for passing a measurement object in the center thereof, and a pair of them. A non-conductor made of a polymer material that electrically insulates the periphery of the conductor and supports the conductors so that the through holes are arranged in a straight line at intervals, and is connected to each conductor to It is characterized in that it is provided with two electric wires penetrating and extending to the outside and having a surface insulated on the outside.

In such a biological electrode, the conductor and the non-conductor are each made of a rubber-like elastic body, and a slit for guiding the object to be measured to the through hole is formed so as to reach the through hole from the surface as a whole. It is preferable that the slit is always closed by elasticity (claim 2). In that case, it is preferable to further include a thread for binding the periphery of the non-conductive body in order to keep the slit closed.

Further, it is preferable that a ground electrode provided on the surface of the non-conductor and a ground wire connected to the ground electrode and having a surface insulated are further provided (claim 4). Further, the non-conductor comprises an interposition member interposed between the conductors, an end face member covering the end faces of the respective conductors, and a tubular member surrounding the entire periphery of the conductor, the interposition member and the end face member. Those are preferable.

[0008]

According to the biological electrode (Claim 1) of the present invention, one measuring object is passed through the through-holes of the pair of electric conductors, and the pair of electric conductors is provided around the distant portion of the measuring object. Can be surrounded by. Since the electric wires are respectively connected to the conductors, by measuring the potential difference between the other ends of the electric wires, the potential difference between the distant portions of the measurement target can be easily measured. Moreover, since the conductor surrounds the entire circumference of the object to be measured, the conventional clamp type, fork type,
As compared with an electrode such as a needle type, it is possible to stably maintain a close contact state with a measurement target. As a result, it can be stably attached even to a thin peripheral nerve. Further, since it is a polymer material, thin and short electrodes can be formed. As a result, the burden on the living body is small even if the device is attached to a large number of places to continue multidimensional measurement. In addition, the conductor is insulated from the surroundings by the non-conductor, and the portion of the electric wire exposed to the outside is also insulated, so that the conductor can be embedded in the living body for measurement. Therefore, the measurement can be stably continued even for a long period of time.

The conductor and the non-conductor are each made of a rubber-like elastic body, and a slit for guiding the object to be measured to the through hole, which reaches the through hole from the surface as a whole, is formed, and the slit is always closed by elasticity. In the living body electrode (claim 2), when the slit is expanded by utilizing elasticity, the through hole is exposed to the outside. Therefore, an object to be measured such as a nerve bundle can be easily inserted into the through hole from the widened slit. Then, when the force for expanding the slit is loosened, the slit naturally closes due to its elasticity, and the object to be measured can be surrounded. Therefore, it is easy to attach and detach the measurement target such as a thin nerve. That is, the biomedical electrode is excellent in that it can be stably attached to the object to be measured and that it can be easily attached and detached.

In the case where the living body electrode provided with the slit is further provided with a ground electrode provided on the surface of the non-conductive body and a ground wire connected to the ground electrode and having a surface insulated (claim) In 3), since the slit is firmly adhered by binding the periphery of the non-conductor with a thread, there is little possibility that the body fluid or the like enters through the slit to break the insulation.

In the case of a living body electrode (claim 4), further comprising a grounding electrode provided on the surface of the non-conductive body and a grounding wire connected to the grounding electrode and having an insulated surface (claim 4). By embedding it in, the tip of the ground wire can be stably and electrically connected to the inside of the living body. Therefore, it is not necessary to separately connect the ground wire, which is used as a reference for the electric potential, to the living body and to remove it.
In addition, by bundling with the electric wire connected to the conductor, the wires can be guided together outside the body.

Further, the non-conductor is an intervening member interposed between the conductors, and an end face member covering the end face of each conductor.
In the biological electrode including a conductor, an intervening member, and a tubular member that surrounds the entire periphery of the end face member (claim 5), one conductor, the intervening member, and the other conductor from the opening at one end of the tubular member. Can be easily assembled by pushing in and attaching end face members to both ends.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the bioelectrode of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway perspective view showing an embodiment of the bioelectrode of the present invention, FIG. 2 is a partial cross-sectional plan view of the bioelectrode, and FIGS. 3a and 3b are the conductive materials used for the bioelectrode. FIG. 4 is a side view of the body and the end face member, FIG. 4 is a perspective view showing another embodiment of the bioelectrode of the present invention, FIG. 5 is a process diagram showing a method of using the bioelectrode of FIG. 2, and FIG. 6 is a bioelectrode of the present invention. FIG. 7a, FIG. 7b and FIG. 7c are partial sectional plan views showing still another embodiment of the present invention.
Is a side view showing yet another embodiment of the bioelectrode of the present invention, FIG. 8a is a side view showing yet another embodiment of the bioelectrode of the present invention, and FIG. 8b is a sectional view taken along line VIII-VIII of FIG. 8a. 9a and 9b are oscillographs showing the relationship between nerve activity and arterial blood pressure measured using the bioelectrode of the present invention.

The biomedical electrode 10 of FIG. 1 has a cylindrical core body 11.
And a cylindrical covering body 12 provided around it. The core body 11 further includes a pair of cylindrical conductors 13 and 14
And the intervening member 15 interposed therebetween and each conductor 1
The end surface members 16 and 17 cover the end surfaces on both sides of the parts 3 and 14. The conductors 13 and 14, the interposition member 15 and the end surface members 16 and 17 have the same diameter, and a through hole 19 for passing the measurement object 18 is formed at the center of each of them.
The covering body 12, the interposition member 15, and the end surface members 16 and 17 are made of a non-conductive material or an insulating material, and form the non-conductive material in the claims. A pair of conductors 1
Measuring wires 21 and 22 are connected to 3 and 14.
Further, the ground electrode 2 made of a conductive material is provided on the outer surface of the cover 12.
3 is provided, and a ground wire 24 is connected to the ground electrode 23. The ground electrode 23 is for contacting a living tissue outside the measurement target such as a nerve bundle and using the potential thereof as a reference potential (ground). Therefore, it can be omitted if unnecessary, such as when the ground wire is separately connected to the living body. The core body 11 and the covering body 12 have slits 26 extending from the through holes 19 to the outer peripheral surface.
Are formed.

For the conductors 13 and 14, a rubber-like conductive polymer material having elasticity such as conductive rubber is used. The intervening member 15 and the end surface members 16 and 17 are preferably made of an insulating polymer material having rubber-like elasticity such as silicone rubber. The conductors 13 and 14, the interposition member 15, and the end surface members 16 and 17 are preferably made of a polymer material having high biocompatibility such as silicone. However, other synthetic resin materials such as polyurethane, nylon elastomer, and fluororesin, or rubber may also be used. Further, it is preferable that the surface of the material is coated with an antithrombotic agent (heparin, urokinase fixing agent, etc.). Further, polymeric materials such as proteins and biopolymers such as collagen are also used. The outer diameter of each of these columnar members is, for example, about 0.5 to 1.5 mm, and if molding is possible, it is preferable to make it as small as possible. The thickness of the conductors 13 and 14 is 0.4-0.
It is about 5 mm, preferably about 0.4 mm. The thicker the longer the area surrounding the object to be measured, the more stable the measurement becomes. On the other hand, when a more compact bioelectrode is desired, it should be as thin as possible within the measurable range and the moldable range. The axial thickness of the end surface members 16 and 17 is preferably as thin as possible within the range where the insulating property can be maintained. Usually, it is about 0.01 to 2.0 mm, especially about 0.01 to 0.05 mm. Moreover, it may be 0.05 to 2.0 mm depending on the case. The thickness of the intervening member 15 in the axial direction regulates the distance between the conductors 13 and 14, and therefore is appropriately determined according to the object of measurement, but is usually about 0.4 to 0.5 mm. The diameter of the through hole 19 depends on the type of the measurement target 18, but is about 0.15 mm in the case of a sympathetic nerve, for example. In addition, it is preferable that several shapes of the through-hole 19 and the bioelectrode are prepared in stages according to the diameter of a measurement target such as a peripheral nerve, and the shapes are selected and used according to the target.

The coating 12 is preferably a polymer material having a rubber-like elasticity and good biocompatibility, such as silicone rubber. The outer diameter of the cover 12 is, for example, about 1 to 2 mm, and the outer diameter of about 1.5 mm is used, and the length is usually 1
It is about 3 mm. However, if molding is possible, it is preferable to make it smaller. The slits 26 formed in the cover 12 and each of the conductors 13 and 14, the intervening member 15, and the end surface members 16 and 17 are usually easy to mold at the stage of parts, but after assembly, for example, It may be formed by cutting with a knife or the like. Furthermore, when cutting with a laser beam or the like, more accurate cutting is possible. In the case of cutting after assembling, it is possible to save the trouble of aligning the slits of the respective parts at the time of assembling. Slit 26
It is preferable that the columnar members are always urged in the closing direction by the elasticity of the columnar members and do not open naturally. The conductors 13, 14, the interposition member 15, and the end surface members 16, 17
Alternatively, the core 11 can be prepared by previously bonding with an adhesive. Further, the cover 12 may be adhered to the core 11.

As shown in FIGS. 2 and 3a, one ends 21a and 22a of the measuring wires 21 and 22 are embedded in the conductors 13 and 14 in a radial direction at a depth that does not reach the through hole 19, and It is bent in the radial direction and extends outward. The extended portions are further provided with conductors 13 and 1
4 is bent parallel to the axis along the surface of the electrode 4, and is bent outward again in the radial direction near the center of the biological electrode 10 in the longitudinal direction, and penetrates the covering 12 to extend to the outside.

One end of the ground wire (reference numeral 24 in FIG. 3b) is joined to the ground electrode 23 from the back side, passes through the inside of the covering 12, and is radially located at the center position of the biological electrode 10 in the longitudinal direction. It is bent and extends to the outside. A portion of the ground wire 24 extending outside is arranged in parallel with the measuring electric wires 21 and 22, and these three electric wires are bundled with a predetermined space therebetween, and then the whole is made of polyurethane or nylon. It is coated with synthetic resin with high biocompatibility such as fluororesin or rubber such as silicone for insulation and reinforcement. Measuring wire 21,
Each of the electric wires 22 and the ground electric wire 24 is, for example, polytetrafluoroethylene (Teflon: a registered trademark of Dyupon Corporation in the United States).
A metal wire having good biocompatibility and high durability, such as a silver wire coated with a fluororesin, is preferably used.
However, it is also possible to use enamel-coated or cashew-coated stainless steel wire or nichrome wire. The diameter of each electric wire is preferably 0.1 mm or less.
For example, in the case of a stainless wire, it is about 0.05 mm. Terminal pins 27 for IC are connected to the other ends of the three electric wires. The terminal pin 27 is preferably connected to an implantable telemeter so that a multi-channel sympathetic nerve activity group can be remotely measured.

In the bioelectrode 30 shown in FIG. 4, a body 31 which is substantially the same as the bioelectrode of FIG. 1 and a slit 2 of the body 31 are provided.
A pair of left and right threads 32 adhered to the portion opposite to 6 are provided. The thread 32 is preferably a thread having high biocompatibility such as silk thread. As shown in FIG. 5, those threads 32 are to be measured 1 such as nerve bundles with the slit 26 of the main body opened.
After inserting 8 into the through hole 19, it is used to tie the ends together and tighten the body 31 so that the slit 26 does not open. This strengthens the adhesion between the surfaces divided by the slit 26, prevents penetration of bodily fluid or the like from the slit 26, and helps maintain the insulation state of the conductor from the outside for a long period of time.

In the biomedical electrode 35 shown in FIG.
An electrode plate 36 made of a conductive resin or the like is embedded in a portion of the inner surface of the electrode that contacts the conductors 13 and 14.
One ends 21a and 22a of the Nos. 1 and 22 are connected to those electrode plates 36, respectively. Since it is not necessary to embed electric wires in the conductors 13 and 14, this product is easy to manufacture. Furthermore, since the conductors 13, 14 and the like can be pushed in from the end portions of the cover 12 during assembly, the assembly work is facilitated.

In the biological electrode 40 shown in FIG. 7a, the conductor 1
The slit 26 formed in 3 or the like extends to the other side beyond the central through hole 19. This has the advantage that the slit 26 can be opened wide. However, when the slit 26 stops at the through hole 19 as shown in FIG. 5, the measurement target 18 stops at the position of the through hole 19, so
There is a merit that positioning is easy.

In the biomedical electrode 42 shown in FIG. 7b, the inner diameter d1 of the covering 12 in its natural state is
It is smaller than the outer diameter d2 of the core 11. Therefore, when the covering body 12 is attached around the core body 11, there is an advantage that the biasing force due to the elastic force for restoring works strongly, and the adhesion between the surfaces divided by the slit 26 becomes high. However, Figure 5
When the slit 26 is opened like a, extra force is required.

In the biological electrode 44 shown in FIG. 7c, the core 11
The cover 12 and the cover 12 are each divided into two halves in the diametrical direction to form halves 45 and 46, and a thread 32 for connecting them is prepared. This is easy to attach to nerves. However, there is a possibility that the removed cover 12 or half of the core 11 may be lost.

The bioelectrode 47 shown in FIG. 8a has the slit 26 opened in a natural state. Therefore, when inserting a nerve or the like into the through hole 19, it is possible to save the trouble of opening the slit 26. Therefore, it is easy to handle. After inserting a nerve or the like into the through hole 19, the biomedical electrode 47 can be used in the same manner as the procedure shown in FIG. It should be noted that, as shown in FIG. 8b, in this biomedical electrode 47, the covering body 12 has a small thickness, so that the entire body is flexible. Further, the cover 12 also integrally covers the outer surfaces of the end face members 16 and 17, which has the effect of making it difficult to separate the parts. The structure and effects of the other parts are the same as those of the bioelectrode 1 shown in FIG.
It is the same as the case of 0.

FIG. 9a is an oscillograph showing together neural activity 51 of the renal sympathetic nerve and arterial blood pressure 52 measured using the bioelectrode of the present invention. By such continuous measurement, the correlation between nerve action and blood pressure can be investigated.
Further, FIG. 9b shows a sympathetic ganglion block treatment (administration of hexamesonium C6) on the animal to be measured after the measurement of FIG. 9a.
It can be seen that the nerve activity 51 of the renal sympathetic nerve disappeared and the arterial blood pressure 52 decreased. From this result, it can be said that the electrode signal recorded by this electrode is sympathetic nerve activity.

The above bioelectrodes are used for motor nerves, sensory nerves,
It is possible to measure nerve discharge in peripheral nerves such as autonomic nerves (sympathetic nerve and parasympathetic nerve). In addition to nerves, excitatory activities of other living tissues (skeletal muscles, smooth muscles, etc.) can be measured and recorded as long as they can be inserted into the through holes of the living body electrodes.

In the above-mentioned embodiment, each of the biomedical electrodes has a cylindrical shape, but it may have a prismatic shape. In the case of the divided structure as shown in FIG. 7c, it is not necessary to have flexibility, and a rigid material having good biocompatibility such as ceramics can be used. However, a polymeric material having flexibility and biocompatibility is preferable in order to protect living tissues such as nerves. In addition, in the above-described embodiment, a pair of conductors are used to record a pair of differential potential differences as a countermeasure against noise (bipolar induction), but only one electrode is wired to a recording device to record from a single pole. It can also be done (unipolar induction).

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a bioelectrode of the present invention.

FIG. 2 is a partial cross-sectional plan view of the biomedical electrode.

3a and 3b are side views of a conductor and a non-conductor used in the bioelectrode, respectively.

FIG. 4 is a perspective view showing another embodiment of the bioelectrode of the present invention.

FIG. 5 is a process drawing showing the method of using the biomedical electrode of FIG.

FIG. 6 is a partial cross-sectional plan view showing still another embodiment of the bioelectrode of the present invention.

7a, 7b and 7c are side views showing yet another embodiment of the bioelectrode of the present invention.

8a is a side view showing still another embodiment of the bioelectrode of the present invention, and FIG. 8b is a sectional view taken along line VIII-VIII of FIG. 8a.

9a and 9b are oscillographs showing the relationship between nerve activity and arterial blood pressure measured using the bioelectrode of the present invention.

10a, 10b and 10c are schematic explanatory views each showing an example of a conventional microelectrode body.

[Explanation of symbols]

10 bioelectrode 11 core 12 Cover 13, 14 Conductor 15 Intervening member 16, 17 End member 18 measurement target 19 through holes 21,22 Measuring wire 23 Earth electrode 24 ground wire 21a, 22a One end of the measuring wire 26 slits 27 terminal pins 30 bioelectrode 31 body 32 threads 35 bioelectrode 36 electrode plate 40 bioelectrode 42 bioelectrode d1 inner diameter d2 outer diameter 44 bioelectrode 45,46 half body 47 bioelectrode 51 Nervous activity 52 Arterial blood pressure

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takako Kawabata             12-12 Sakaemachi, Takarazuka-shi, Hyogo Nihonke             Cable System Co., Ltd. (72) Inventor Kazuhiko Kondo             12-12 Sakaemachi, Takarazuka-shi, Hyogo Nihonke             Cable System Co., Ltd. (72) Inventor Yasuo Seki             12-12 Sakaemachi, Takarazuka-shi, Hyogo Nihonke             Cable System Co., Ltd.

Claims (5)

[Claims] 1. A pair of conductors made of a polymer material, each of which has a through hole for passing an object to be measured in the center, and the surroundings of these conductors are electrically insulated, and the conductors are formed such that the through holes are linear. A non-conductor made of a polymer material that is supported in parallel with each other at intervals, and two that are connected to each conductor and extend to the outside through the non-conductor, and the surface is insulated outside Ultra-compact bio-electrode for measuring nerve activity etc. 2. The conductor and the non-conductor are each made of a rubber-like elastic body, and a slit for guiding a measurement object to the through hole, which reaches the through hole from the surface as a whole, is formed, and the slit is elastic. The biological electrode according to claim 1, which is always closed by. 3. The bioelectrode according to claim 2, further comprising a thread for binding the periphery of the non-conductor so as to keep the slit closed. 4. The biological electrode according to claim 1, further comprising a ground electrode provided on the surface of the non-conductive body, and a ground wire connected to the ground electrode and having an insulated surface. 5. The non-conductor is a tubular member that surrounds the interposition member interposed between the conductors, the end face member that covers the end face of each conductor, and the entire periphery of the conductor, the interposition member, and the end face member. The biological electrode according to claim 1, which comprises a member.