JPH0225368Y2 - - Google Patents

Description

[Detailed description of the invention] Background of the invention (technical field) This invention relates to an indifferent electrode used when detecting biological information as an electrical signal.

(Prior Art) Various types of indifferent electrodes have been proposed in the past. For example, there are methods in which the electrode itself is attached by pressing it against the epithelium, methods in which the electrode is directly implanted into the body, and methods in which the electrode is placed in a cylindrical base.
A method is known in which an indwelling needle is connected to this cylindrical base and the inside of the cylindrical base and the indwelling needle are filled with reagent and/or body fluid, which is equivalent to directly implanting the electrode into the body. .

This last method that connects to an indwelling needle has only the indwelling needle in the body, so
This is advantageous in that there are few restrictions on the material, shape, etc. of the electrodes, and they can be set arbitrarily. In this case, the electrode needs to be in sufficient contact with the body through the reagent and/or body fluid inside the cylindrical substrate and indwelling needle, and therefore cotton thread is filled around the electrode as a water retaining material.

(Problems with the prior art) However, indifferent electrodes using this cotton thread as a water-retaining material may not contain enough water, and close contact between the electrode and the test solution and/or body fluid may not always be sufficient. The inventor of the present invention has discovered that there is a problem in that it is not possible to obtain stable biological information. Furthermore, the indifferent electrode of this type has a problem in that the engagement between the cylindrical base and the indwelling needle is a tapered joint, which is insufficient and may come off during use.

Purpose of the invention This invention provides an indifferent electrode that is connected to an indwelling needle and has good contact with the test solution and/or body fluid, making it possible to always obtain stable biological information. The purpose is to

A further object of this invention is to provide an indifferent electrode that can be reliably connected to an indwelling needle.

That is, this invention includes a cylindrical base having an engagement part with the hub part of an indwelling needle at one end and a lead wire holding part connected to a potential measuring device at the other end; a plurality of hydrophilic electrodes disposed extending in the hand direction and electrically connected to the lead wires; and a plurality of hydrophilic electrodes disposed between the cylindrical body and the electrodes so that a portion thereof contacts the electrodes; The present invention provides an indifferent electrode comprising: a porous hollow fiber;

Furthermore, this invention provides the above-mentioned indifferent electrode, wherein the engaging portion has a locking mechanism.

Furthermore, this invention provides an indifferent electrode characterized in that a plurality of hydrophilic porous hollow fibers are arranged substantially parallel to each other along the electrode.

Specific Description of the Invention This invention will be described below with reference to illustrated embodiments.

Figure 1 shows how an indifferent electrode is used. In the figure, 1 is an indifferent electrode, from which a reference potential is derived, and on the other hand, an indifferent electrode is placed at a location in the living body to be measured. The electrode 2 guides the action potential at that location to a potential measuring device, and the change in potential at that location is recorded as biological information.

Figure 2 shows - of the indifferent electrode 1 shown in Figure 1.
As is clear from the line sectional view, the base of the indifferent electrode 1 has a substantially cylindrical shape, and one end of the indifferent electrode 1 has a two-piece structure consisting of an inner cylinder 7 and an outer cylinder 4 provided coaxially around the outer periphery of the indifferent electrode 1. It forms an engaging part with a heavy-duty indwelling needle. To explain this in more detail, the inner wall of the outer cylinder 4 of the double-structured engagement part is formed with a thread 6 that screws into the hub part of the indwelling needle 5 (see Figure 4), and the tip An inner cylinder 7 having a tapered outer surface that becomes thinner in the direction is opened coaxially and slightly protruding forward from the outer cylinder 4. A sealing member 12 having a through hole in the center for holding a lead wire is attached to the other end of the indifferent electrode 1, and one end of the lead wire 8, which is electrically connected to the measuring device 3 through this through hole, is connected to the inside of the sealing member 12. While inserted into the tube 7, it is fixed with solder, adhesive, etc. 9. A linear electrode 10 is connected to the end of the inserted lead wire 8, and this electrode 10 extends to the vicinity of the tip of the inner cylinder 7. As shown in FIGS. 2 and 3, between the outer periphery of the electrode 10 and the inner wall of the inner cylinder 7, a large number of hydrophilic porous hollow fibers 11 are arranged in parallel along the longitudinal direction of the electrode 10, and one of them The electrodes 10 are densely packed so that the parts are in contact with the electrodes 10.

As this porous hollow fiber 11, a cellulose membrane,
Porous hollow fibers made of a polyolefin resin such as polypropylene or polyethylene and having an inner diameter of 150 to 250 μm, a wall thickness of 8 to 17 μm, and an average pore diameter of 15 to 30 Å are suitable.

As the electrode 10, metals such as silver, platinum, tungsten, and stainless steel, silver silver chloride, platinum black electrodes with metal surface treatment, carbon, and semiconductors can also be used.

As the material of the base body of the indifferent electrode (including the inner tube 7 and the outer tube 4), an insulating material such as a synthetic resin such as polypropyne, polycarbonate, polyvinyl chloride, etc. can generally be used.

Specific operation of the invention As shown in FIG. 4, the indifferent electrode 1 is constructed by screwing the hub part of the indwelling needle 5 into the outer cylinder 4 at the tip of the engaging part, which has a double pipe structure. After connecting the indwelling needle 5 to the
is pierced, and by utilizing the internal space of the hydrophilic porous hollow fibers 11 and the capillary phenomenon between the fibers, the interior of the inner tube 7 is filled with body fluids, reagents, etc., and water is sufficiently retained. That is, body fluid introduced into the hollow fiber 11 by capillary phenomenon,
The test liquid and the like are led out of the hollow fiber from the wall surface of the hollow fiber 11 through the pores in the porous material, filling the inside of the inner cylinder 7, and the liquid is brought into contact with the electrode 10. Thereby, it is possible to derive a potential at a predetermined location of the living body 13 in a state equivalent to that when the electrode 10 is fully contacted with body fluids and the like and is implanted in the body.

Specific effects of the invention As detailed above, according to the invention, since hydrophilic porous hollow fibers are filled around the electrode, the absorption of test liquids and/or body fluids is improved due to the capillary phenomenon in the internal space of the hollow fibers. , Therefore, sufficient contact between the electrode and body fluid etc. is achieved, and stable biological information can be obtained.

Furthermore, since the indifferent electrode and the indwelling needle are connected by screwing together, there is no risk of them coming apart from the indwelling needle during use. In addition to the above-mentioned screw connection, the connection method with the indwelling needle may be other than the above-mentioned screw connection.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating how the indifferent electrode of the present invention is used, FIG. 2 is a cross-sectional view of the indifferent electrode of the present invention shown in FIG. 1 along the line -, and FIG.
FIG. 4 is a cross-sectional view taken along a line showing the state in which the indwelling needle and the indifferent electrode are fitted. 1...Indifferent electrode, 4...Outer tube, 5...Indwelling needle,
6...Screw thread, 7...Inner cylinder, 8...Lead wire, 9
... Adhesive, 10 ... Electrode, 11 ... Porous hollow fiber, 12 ... Sealing member, 13 ... Living body.

Claims (1)

[Claims for Utility Model Registration] (1) A cylindrical base having an engaging part with the hub part of an indwelling needle at one end and a lead wire holding part connected to a potential measuring device at the other end; an electrode disposed within the base extending in the longitudinal direction of the base and electrically connected to the lead wire; provided between the cylindrical body and the electrode;
and a plurality of hydrophilic porous hollow fibers disposed so as to partially contact the electrode. (2) The indifferent electrode according to claim 1, wherein the plurality of hydrophilic porous hollow fibers are arranged substantially parallel to each other along the electrode.