WO2013140734A1

WO2013140734A1 - X-ray transmissive bio-electrode

Info

Publication number: WO2013140734A1
Application number: PCT/JP2013/001497
Authority: WO
Inventors: Ryugo ODAKA
Original assignee: Nihon Kohden Corporation
Priority date: 2012-03-21
Filing date: 2013-03-08
Publication date: 2013-09-26
Also published as: JP2013192818A; JP5993594B2

Abstract

[PROBLEM] To provide a bio-electrode using an electrode element which enables to transmit X-rays, has corrosion resistance against the conductive gel, which is a component member of the bio-electrode, and also is low price. [SOLUTION] It is attained by a bio-electrode containing: conductive gel; an electrode element; a cable for electrically connecting the bio-electrode and external devices; wherein the electrode element is a thin film formed by using an Al alloy which transmits X-rays and has corrosion resistance against the conductive gel. [SELECTED DRAWING]: FIG. 1

Description

X-RAY TRANSMISSIVE BIO-ELECTRODE

Background

TECHNICAL FIELD
The present invention relates to a X-ray transmissive bio-electrode (including medical use). More specifically, the present invention relates to a X-ray transmissive bio-electrode utilizable to a defibrillation electrode, a transcutaneous pacing electrode, an electrocardiogram electrode, a return electrode or the like.

Description of Related Art
Conventionally, it is general that an electrode element to be used for the bio-electrode has a button-type of a metal foil such as tin (Sn), or stainless steel (SUS) or the like (for example, refer to PATENT DOCUMENT 1). In addition, there has been proposed the bio-electrode using a carbon film or a carbon resin for an electrode element, to transmit X-rays (for example, refer to PATENT DOCUMENT 2).

[PATENT LITERATURE 1] JP-A-10-507651, from page 8, last line, to page 9, line 1.
[PATENT LITERATURE 2] JP-A-2008-86764, paragraph 0017

However, in the case where the bio-electrode does not transmit X-rays, like the button-type electrode element made of Sn foil or SUS described in PATENT LITERATURE 1, there is a problem that an electrode attached on the body surface gives a shade in X-ray inspection. Then, there is a problem that the electrode attached to the body surface should be attached by shifting from a suitable position during X-ray inspection. There is also a problem that, when the shift of the electrode from a suitable position is impossible due to a small body such as a child or a female or depending on the attached position, the electrode is peeled off during X-ray irradiation. In addition, the electrode element using a metal such as the Sn foil had a disadvantage of corrosion (rusting), discoloring of conductive gel or the like. The bio-electrode described in PATENT LITERATURE 2, which uses for the electrode a carbon film or a carbon resin for an element had a problem of expensive as a disposable electrode, and thus not matching in view of cost.

Although it is also considered to use an aluminum (Al) foil as the electrode element to transmit X-rays, it is a problem that the electrode is not suitable for practical use due to corrosion of the aluminum foil of the electrode element, caused by contact with conductive gel, which is a component of the bio-electrode. Currently, the bio-electrode using the aluminum foil as the electrode element has not been proposed, and there has been no practical use example at all.

Summary

This invention provides a bio-electrode using an electrode element which transmits X-rays and has corrosion resistance against the conductive gel, a component of the bio-electrode, and is inexpensive.

One aspect of the present invention proveides a bio-electrode using an Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel to be used in the bio-electrode, for the electrode element.

Fig. 1 is a schematic drawing schematically illustrating a disassembled state into each of the general components of a disposable pad electrode used in various defibrillators (for example, an external defibrillator, a semi-automated defibrillator, an Automated External Defibrillator (AED) and the like), as one embodiment of the bio-electrode of the present invention. Fig. 2 is a schematic drawing illustrating a state that a disposable pad electrode is configured to be attached to a patient. Fig. 3A is a schematic drawing schematically illustrating a return electrode to be used to one side of an electrosurgical knife, as one embodiment of the bio-electrode of the present invention. Fig. 3B is a cross-sectional view along the A-A line of Fig. 3A.

DETAILED DESCRIPTION

Explanation will be given below on embodiments of the present invention with reference to accompanying drawings. It should be noted that the same reference code was given to the same element in explanation of drawings to omit duplicated explanation. Dimensional scale ratio of the drawings may be exaggerated for convenience of explanation, and thus it may be different from actual scale ratio in some cases.

The bio-electrode of the present invention is a bio-electrode comprising:
conductive gel;
an electrode element;
a cable for electrically connecting the bio-electrode and an external device;
wherein the electrode element is a thin film formed by using an Al alloy which transmits X-rays and has corrosion resistance against the conductive gel. By adopting such a constitution, a X-ray transmissive inexpensive bio-electrode having corrosion resistance against the conductive gel, and can be provided.

According to the present invention, by using an Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel to be used in the bio-electrode, for the electrode element, a X-ray transmissive and inexpensive bio-electrode having corrosion resistance can be attained. Explanation will be given below on the bio-electrode of the present invention with reference to drawings.

Fig. 1 is a schematic drawing schematically showing a disassembled state into each of the general components of a disposable pad electrode used in various defibrillators (for example, an external defibrillator, a semi-automated defibrillator, an Automated External Defibrillator (referred to as AED or also PAD) and the like), as one embodiment of the bio-electrode of the present invention.

As shown in Fig. 1, a disposable pad electrode (it may be referred to simply as a pad electrode) 10 can include, as general components, a label 11, a rivet 12, a ring washer 13a, a substrate tape 14, an electrode element (hereafter, it may be referred to as an aluminum element) 15, a ring washer 13b, a cable 16, a conductive gel 17, a cover tape 18 and a release sheet 19, in this order, from the surface side (an opposite side from the attached surface to the body surface). Explanation will be given below on each component of the disposable pad electrode 10 and function thereof.

(1) The label 11
The label 11 is provided to prevent the rivet 12 and the ring washer 13a from being exposed (that is, a human contacting to the exposed portion gets electric shock by electricity flowing) by covering the rivet 12 and the ring washer 13a, so as to be adhered and fixed at the surface side of the substrate tape 14. The label 11 is usually composed of an insulating sheet substrate 11a of a circular shape or the like, which is slightly larger than the rivet 12 and the ring washer 13a, and an adhesive layer 11b, which is formed by adhesives coated on the rear surface of said sheet substrate 11a (the attached surface side to the body surface).

The label 11 is not especially limited, and conventionally known one may be utilized as it is.

Material of the sheet substrate 11a is also not especially limited, however, such one is desirable that raises no problem of deterioration within a guarantee period of the product (the disposable pad electrode 10 or an AED using said electrode 10, and the like), or breakage in peeling the release sheet 19 to attach the pad electrode 10 onto the body surface. A conventionally known one such as insulating papers or various resins (for example, polyethylene (PE), polyethylene terephthalate (PET), synthetic paper, and the like) may be used.

Thickness of the sheet substrate 11a is desirably as thin as possible so as not to be caught by something, as long as a problem of breakage or the like does not occur in attaching the pad electrode 10 onto the body surface, and it may be enough within a range of 20 to 150 um (micrometer). However, the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

A material of the adhesive layer 11b is not especially limited, and conventionally known various kinds of adhesives may be utilized. Adhesives or pressure sensitive adhesives based on natural rubber, acrylic based or urethane based adhesives or pressure sensitive adhesives may be exemplified. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. In particular, acrylic based pressure sensitive adhesives and the like are preferable, having superior adhesive property both to insulating papers or resins (the sheet substrate 11a) and metal (the rivet 12 or the ring washer 13a).

Thickness of the adhesive layer 11b may also be any thickness as long as it can provide sufficient adhesive strength, and may be in a range of about 5 to 40 um (micrometer). However, even the cases out of the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Shape (form) of the label 11 is not especially limited, however, as shown in Fig. 1, a circular shape is a generally used shape. However, any shape other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Size of the label 11 is usually enough to be slightly larger than that of the rivet 12 and the ring washer 13a, and circular shaped one with a diameter of about 3 (plus or minus 1) cm is used. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

(2) The rivet 12 and the

ring washers

13a, 13b
What is called a fixing (caulking) member, composed of the rivet 12 and the

ring washers

13a, 13b, is provided to fix the cable 16, the aluminum element 15 and the substrate tape 14. As shown in Fig. 1, at the end of the aluminum element 15 and the substrate tape 14 (as shown in Fig. 1, at the center of the vicinity of a shorter side of the aluminum element 15 and the substrate tape 14), through holes 14a, 15a into which the rivet 12 is inserted are provided, so as to match (overlap) the positions of both through holes when affixing them each other. Similarly, at the tip of the cable 16, which is electrically connected to the aluminum element 15, the fastener 16b having the through hole 16c with the same size as that of the through holes 14a, 15a is provided. Using such a configuration, fixation is performed by inserting and caulking the rivet 12 into each the ring washer 13a, through hole 14a of the substrate tape 14, through hole 15a of the aluminum element 15, the ring washer 13b and the through hole 16c of the fastener 16b at the tip of the cable body 16a.

As the rivet 12 and the

ring washers

13a, 13b, a conventionally known one may be utilized as it is.

Material of the rivet 12 and the

ring washers

13a, 13b is not especially limited, as long as they are a material having electric conductivity, and metal (including an alloy) such as stainless steel (SUS) or Al may be used.

Size of the rivet 12 and size of inner diameter (through hole) of the

ring washers

13a, 13b (both sizes are nearly common) may be enough in a range of about 2 to 5 mm. However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. Similarly, size of outer diameter of the

ring washers

13a, 13b may be enough in a range of about 10 to 20 mm, and thickness of the

ring washers

13a, 13b may be enough in a range of about 0.5 to 2 mm. However, even these sizes or thicknesses outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. Length of the rivet 12 may be determined as appropriate not to impair the effect(s) of the present invention, based on thickness of the cable 16, the aluminum element 15 and the substrate tape 14 to be fixed.

(3) The substrate tape 14
The substrate tape 14 is provided to support (fix or reinforce) the aluminum element 15. That is, it is provided as a reinforcing material so that the aluminum element 15 of a thin film is prevented from breaking, wrinkling or flexing. It is also provided to prevent the surface side (the opposite side of the attached side to the body surface) of the aluminum element 15 from being bare (causing electric shock). It can also be provided to form an adhesive layer of the rear surface (surface side attached to the body surface) of the peripheral of the substrate tape 14 exceeding the affixed part with the aluminum element 15, by making slightly larger than that of the aluminum element 15, to be attached to skin (body surface) of a human or animal (mainly pets or mammals of a zoo or the like).

The substrate tape 14 is usually composed of an insulating substrate tape body 14b, which is slightly larger than that of the electrode element 15 and the conductive gel 17, and an adhesive layer 14c formed on the rear surface (attached surface side to the body surface) of said substrate tape body 14b.

The substrate tape body 14b also has function (role) as a reinforcing material so that the aluminum element 15 of a thin film is prevented from breaking, wrinkling or flexing. If the function (role) as a reinforcing material can be sufficiently exerted, such a material and thickness may be enough.

A material of the substrate tape body 14b is not especially limited as long as it is insulating and exerts function as a reinforcing material of the aluminum element 15, and conventionally known one such as polyethylene (PE), polyethylene terephthalate (PET), and polyurethane may be used. In particular, it is desirable to use a material which is expandable, has high insulating property, flexibility and cushioning property, and sufficiently exerts function as a reinforcing material for the aluminum element 15, such as polyethylene foam or the like. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Thickness of the substrate tape body 14b is also desirably thin as long as it maintains insulating property and the aluminum element 15 is prevented from breaking, wrinkling or flexing. The thickness may be in a range of about 0.5 to 2 um (micrometer). However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention

As material of the adhesive layer 14c, conventionally known various kinds of pressure sensitive adhesives may be utilized. Pressure sensitive adhesives based on, natural rubber, acrylic based or urethane based pressure sensitive adhesives may be exemplified. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. In particular, the acrylic based pressure sensitive adhesives and the like are preferable, because they have sufficient adhesiveness strength to the aluminum element 15 and the body surface (skin), as well as enables to be easily peeled from the body surface (skin) after use.

Thickness of the adhesive layer 14c may be any thickness if it provides sufficient adhesiveness strength to the body surface (skin). The thickness may be in a range of about 5 to 40 um (micrometer). However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Form (shape) of the substrate tape 14 is not especially limited, however, a rectangular shape rounded at the four corners as shown in Fig. 1 is a generally used shape. However, any form other than exemplified in the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention

Size of the substrate tape 14 is any size if it is slightly larger than that of the aluminum element 15 and the conductive gel 17. A rectangular shape rounded at the four corners with a size of about 13 (plus or minus 3) cm x 11 (plus or minus 3) cm is usually used. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention

(4) The electrode element 15
The electrode element (aluminum element) 15 is provided to electrically bridge a cable 16 and a conductive gel 17

The electrode element (aluminum element) 15 is formed by use of an Al alloy which transmits X-rays and has corrosion resistance against the conductive gel 17. By such a constitution, a X-ray transmissive and inexpensive bio-electrode having corrosion resistance can be provided.

(A) A first embodiment of the Al alloy
In detail, the first embodiment of the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, is an Al alloy containing Mn. Specifically, the Al alloy, which has corrosion resistance against the conductive gel 17, contains Mn, and a content of Mn is in a range of 0.1 to 6% by mass, and preferably in a range of 1 to 4% by mass. By containing Mn in the Al alloy in the above range, the alloy can transmit X-rays and have high corrosion resistance against the conductive gel 17. In more detail, the first embodiment of the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, contains Mn, the remaining part being composed of Al and impurities, wherein content of the Mn is in a range of 0.1 to 6% by mass, and more preferably in a range of 1 to 4% by mass, and the impurities have at least one of Mg, Si, Cu, Fe and Zn in. In more specifically, the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, is an Al alloy containing Mn, the remaining part being composed of Al and impurities, wherein content of the Mn is in a range of 0.1 to 6% by mass, more preferably 1 to 4% by mass, the impurities contain at least one of Mg, Si, Cu, Fe and Zn, and content of Mg, Si, Cu, Fe and Zn of the impurities is each 0.03% by mass or less, preferably 0.01% by mass or less and more preferably 0.001% by mass or less. By containing of Mn in the Al alloy within the above range and limiting the impurities to the above elements and content range, formability can be enhanced, while maintaining X-ray transmission and high corrosion resistance against the conductive gel 17.

(B) A second embodiment of the Al alloy
In detail, the second embodiment of the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, contains Mn and Mg. Specifically, the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, contains Mn and Mg, and content of Mn and Mg is each in a range of 0.1 to 6% by mass, and preferably in a range of 1 to 4% by mass. By containing Mn and Mg in the Al alloy within the above range, the alloy can be X-ray transmissive and have high corrosion resistance against the conductive gel 17. In more detail, the second embodiment of the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, contains Mn and Mg, the remaining part being composed of Al and impurities, content of Mn and Mg is each in a range of 0.1 to 6% by mass, and preferably in a range of 1 to 4% by mass, and having at least one of Si, Cu, Fe and Zn in the impurities. In more specifically, the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, is an Al alloy containing Mn and Mg, the remaining part being composed of Al and impurities, wherein content of Mn and Mg is each in a range of 0.1 to 6% by mass, and preferably in a range of 1 to 4% by mass, the impurities contain at least one of Si, Cu, Fe and Zn, and content of Si, Cu, Fe and Zn in the impurities is each 0.03% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less. By containing Mn and Mg in the Al alloy within the above range and limiting the impurities to the above elements and content range, formability can be enhanced, while maintaining X-ray transmission and high corrosion resistance against the conductive gel 17.

(a) Al content
In the Al alloy, which transmits X-rays and has corrosion resistance against the conductive gel 17, Al content (purity) measured in accordance with JIS H 2111 may be a remaining portion excluding contents of Mn and impurities in the first embodiment. Al content may be about 94 to 99.9% by mass, however, it may not necessarily be within the range. Similarly, in the second embodiment, content of Al may be enough a remaining portion excluding contents of Mn, Mg and impurities, and the content may be about 94 to 99.9% by mass, however, it may not necessarily be within the range

(b) Mn content
In the first and the second embodiments of the Al alloy, Mn is an element, which can make the Al alloy to transmit X-rays and enhance elongation, that is, formability, without decreasing corrosion resistance against the conductive gel 17. Content of Mn below 0.1% by mass could incur decrease in corrosion resistance against the conductive gel 17. Content of Mn over 6% by mass could cause difficult formation of a thin film of the Al alloy, due to decrease in formability. Accordingly, content of Mn is desirably in a range of 0.1 to 6% by mass. Content of Mn is more desirably in a range of 1 to 4% by mass, to attain both corrosion resistance and formability (processability) of the Al alloy.

(c1) Mg content of the first embodiment
Next, in the Al alloy of the first embodiment, Mn is used as an effective component and it is found that extremely trace amount of Mg included therein unexpectedly decreases corrosion resistance of the Al alloy. The content of Mg is desirably removed (reduced) down to 0.05% by mass or lower, preferably 0.01% by mass or lower and more preferably 0.001% by mass or lower. As a method for removing (reducing) content of impurity Mg in the Al alloy down to 0.05% by mass or lower, for example, high purity Al metal obtained by high-grade trinal electrolytic process may be used as appropriate. The lower limit of the content of Mg is not especially limited, however, it is usually about 0.00001% by mass. Because, in order to decrease content of Mg below 0.00001% by mass, repeating trinal electrolytic process or the like is required, which significantly increases production cost.

(c2) Mg content of the second embodiment
Next, in the Al alloy of the second embodiment, it is found that, by addition of Mg along with Mn in predetermined amount, Mn can be an element enabling to enhance strength or formability without deteriorating corrosion resistance of the Al alloy. Content of Mg below 0.1% by mass could incur decrease in corrosion resistance against the conductive gel 17. Content of Mg over 6% by mass could cause difficult formation of a thin film of the Al alloy due to decrease in formability. Accordingly, content of Mg is desirably in a range of 0.1 to 6% by mass. Content of Mg in a range of 1 to 4% by mass is more desirable, in view of enhancing corrosion resistance, strength and formability (processability) of the Al alloy.

(d) Si content of impurity
In the Al alloy any of the first and the second embodiments, presence of impurity Si in the Al alloy significantly decreases corrosion resistance against the conductive gel 17, in particular, causing pitting corrosion. Accordingly, content of Si is desirably removed (decreased) down to 0.03% by mass or lower, preferably 0.01% by mass or lower, and more preferably 0.001% by mass or lower. When content of Si decreases in the Al alloy, crystal particle size of the Al alloy decreases. Thereby, proof stress, that is, strength of the Al alloy can be increased and also elongation, that is, formability of the Al alloy can be enhanced. Content of Si is preferably decreased down to 0.001% by mass or lower, and more preferably 0.0005% by mass or lower, to exert these characteristics, while maintaining high corrosion resistance of the Al alloy against the conductive gel 17. However, as characteristics required for the pad electrode 10, strength is not especially necessary, and it is enough for them to have corrosion resistance against the conductive gel 17, electric conductivity (conductivity) and X-ray transmission, and to be formed into a thin film having predetermined thickness, therefore, characteristics required to the pad electrode 10 can be exerted sufficiently without necessarily decreasing the content of Si down to 0.001% by mass or lower. The lower limit of the content of Si is not especially limited, however, it is usually about 0.00001% by mass. Because, to decrease content of Si below 0.00001% by mass, repeating trinal electrolytic process or the like is required, which significantly increases production cost.

(e) Cu content of impurity
In the Al alloy any of the first and the second embodiments, presence of even trace amount of Cu in the Al alloy decreases corrosion resistance of the Al alloy. Therefore, content of Cu is desirably removed (decreased) down to 0.03% by mass or lower, preferably 0.01% by mass or lower, and more preferably 0.001% by mass or lower. The lower limit of the content of Cu is not especially limited, however, about 0.00001% by mass. It is because, to decrease content of Cu below 0.00001% by mass, further repeating fractionation crystallization method or the like is required, which significantly increases production cost.

(f) Fe content of impurity
In the Al alloy any of the first and the second embodiments, Fe of impurity forms, together with Mn, an intermetallic compound of Al-Fe-Mn. The intermetalic compound of Al-Fe-Mn is represented by Al₆ (Fe, Mn) or the like and it is different from an intermetallic compound Al₆Mn based on Al- Mn. Al₆ (Fe, Mn) significantly decreases corrosion resistance against the conductive gel 17, causing pitting corrosion and general corrosion. From the above reason, the content of impurity Fe is desirably removed (decreased) down to 0.05% by mass or lower, preferably 0.01% by mass or lower, and more preferably 0.001% by mass or lower. The content of Fe over 0.05% by mass significantly decreases corrosion resistance. As a method for removing (reducing) content of impurity Fe in the Al alloy down to 0.05% by mass or lower, for example, high purity Al metal obtained by a high-grade trinal electrolytic process may be used as appropriate. The lower limit of the content of impurity Fe is not especially limited, however, it is usually about 0.00001% by mass. It is because, to decrease content of Fe below 0.00001% by mass, repeating trinal electrolytic process or the like is required, which significantly increases production cost.

(g) Zn content of impurity
In the Al alloy any of the first and the second embodiments, presence of Zn even in trace amount in the Al alloy decreases corrosion resistance of the Al alloy against the conductive gel 17. Therefore, content of impurity Zn is desirably removed (decreased) down to 0.05% by mass or lower, preferably 0.01% by mass or lower, and more preferably 0.001% by mass or lower. As a method for removing (reducing) content of impurity Zn in the Al alloy down to 0.05% by mass or lower, for example, high purity Al metal obtained by a high-grade trinal electrolytic process may be used as appropriate. The lower limit of the content of Zn is not especially limited, however, it is usually about 0.00001% by mass. Because, in order to decrease content of Zn below 0.00001% by mass, repeating trinal electrolytic process or the like is required, which significantly increases production cost.

(h) About other elements contained in the Al alloy
In the Al alloy any of the first and the second embodiments, a transition metal such as V (vanadium), Ti (titanium), Zr (zirconium), Cr (chromium), Ni (nickel), or an element such as B (boron), Ga (gallium), Bi (bismuth) may be contained in the Al alloy, as long as it is included in a content within a range not to impair corrosion resistance against the conductive gel 17, electric conductivity (conductivity), and X-ray transmission, that is, the effects of this invention.

As described above, in the Al alloy any of the first and the second embodiments, by adding the above additive elements into the Al alloy in the optimal amount (and still more by decreasing impurity amount), recrystallized structure of the Al alloy can be ultra fine. Thereby, corrosion resistance and formability of the Al alloy can be improved at the same time. That is, in the Al alloy of the first embodiment, by optimizing content of Mn, the additive element, and in the Al alloy of the second embodiment, by optimizing content of Mn and Mg, the additive elements, and still more by decreasing content of an element, which significantly decreases corrosion resistance against the conductive gel 17, of impurity Cu or the like, superior corrosion resistance is attained, resulting in that the corrosion resistance is sufficient to prevent progress of pitting corrosion or general corrosion caused by the conductive gel 17, during predetermined period (guaranteed period of a product; for example, usually for 24 months for a defibrillator).

The aluminum element 15 is a thin film with a thickness of 9 to 200 um (micrometer) formed by using the Al alloy having corrosion resistance against the conductive gel 17, electric conductivity (conductive) and X-ray transmission. As a thin film with the above-mentioned thickness, a thin film of a foil of the Al alloy formed by a rolling process or the like, or a button-type can be used.

Form (shape) of the aluminum element 15 is not especially limited, however, a rectangular shape rounded at the four corners, as shown in Fig. 1, is generally used shape. However, any form other than exemplified in the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Size of the aluminum element 15 is usually slightly larger than that of the substrate tape 14 and the conductive gel 17, and a rectangular shape rounded at the four corners with a size of about 10 (plus or minus 3) cm x 9 (plus or minus 3) cm is used. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Although not shown in Fig. 1, to prevent a thin and easily breakable aluminum element 15 from breaking, as a backing material (reinforcing material) 15b of the aluminum element 15, a polyethylene terephthalate (PET) sheet or a polyethylene (PE) sheet is desirably used by laminating on the substrate tape 14 side of the aluminum element 15. The above backing material (reinforcing material) 15b is not especially limited, and conventionally known various kinds of resin sheets may be utilized, and any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Thickness of the backing material (reinforcing material) 15b is usually enough to be 5 to 100 um (micrometer) and the thinner is the better in view of weight reduction of the pad electrode 10, as long as it prevents the thin and easily breakable aluminum element 15 from breaking .

For the above backing material (reinforcing material) 15b as well, a (not shown) adhesive layer is provided on the surface adhered to the aluminum element 15. Such an adhesive layer is also not especially limited, and conventionally known various kinds of adhesives may be available. Adhesives based on natural rubber, acrylic based or urethane based adhesives or the like may be exemplified. However, any material other than exemplified in the above range may be applicable sufficiently as long as it is within a range not to impair the effect(s) of the present invention.

(5) The cable 16
Fig. 2 is a schematic drawing showing a state that the pad electrode 10 is configured to be attached to a patient.

As shown in Figs. 1 and 2, the cable 16 is for connecting (electrically connecting) a defibrillator body 20 and the pad electrode 10 (in detail, the aluminum element 15) attached to a patient 21. As shown in Fig. 1, the cable 16 has the cable body (lead wire) 16a, and at one tip of the through hole 16c, which is electrically connected to the pad electrode 10, the fastener 16b having the through hole 16c is provided, to be fixed together with the aluminum element 15 and the substrate tape 14, by the rivet 12 and the

ring washers

13a, 13b. As shown in Fig. 2, the other tip of the cable 16 is electrically connected to the defibrillator body 20, usually according to the following two embodiments.

That is, the other tip of the cable body 16a may be (i) connected directly to a body of a defibrillator, or (ii) as shown in Fig. 2, a connector 23b may be provided, which is capable of connecting to a connector 23a provided at the tip of another cable (lead wire) 22 connected to the defibrillator body 20. For example, like an Automated External Defibrillator (AED), the embodiment(i) consolidated with a body of a defibrillator is desirable in consideration of convenience, because, there may also be the case that an ordinary person other than a doctor or an emergency medical technician, as an operator, uses it outdoors other than in a hospital or in an ambulance. In addition, in the case that an operator (mainly a doctor or an emergency medical technician or the like) utilizes it for many patients in a hospital or in an ambulance such as an external defibrillator (including a semi-automated defibrillator, an Automated External Defibrillator (AED)), the embodiment (ii) to be separated from the connector 23b is desirable, because, only the disposable pad electrode (pad) 10 can be exchanged by each patient, while maintaining the body of a defibrillator as it is. In this case, by using the disposable pad electrode 10, an operator is not required to keep the pad electrode 10, which is superior in view of preventing hospital infection or the like.

The cable body 16a is not especially limited, and conventionally known material may be used. For example, a conventionally known one, such as a carbon wire, a tin plated Cu wire, an Al wire coated with an insulating material can be utilized.

As material of the fastener 16b, a conductive material is enough and, for example, brass, Al or the like may be used.

The connector 23b at the cable 16 side is not especially limited, and conventionally known connecters may be utilized, as long as it is connectable to the connector 23a provided at the end of other cable 22 connected to the defibrillator body 20.

(6) The conductive gel 17
The conductive gel 17 is provided to be adhered and also electrically connected to skin of human being or animal. As this conductive gel 17, usually a gel containing water and flowing electricity (having conductivity) has been used generally. In addition, for this conductive gel 17, a conductive gel with self-adhesiveness, having skin compatibility, has been utilized suitably.

The conductive gel 17 is not especially limited, and conventionally known various kinds of conductive gel with self-adhesiveness, having skin compatibility, may be utilized suitably. For example, a pressure sensitive adhesive composition shown below may be used, which has been disclosed in JP-A-2002-356661, which has been proposed already by the present applicant. The gel is composed of a combination of a cross-linked copolymer of an alkoxypolyethylene glycol mono (meth) acrylate and an unsaturated carboxylic acid such as acrylic acid, partially neutralized or not neutralized, polyethylene glycol monoalkyl ether and water. The inventor has found that the gel exhibits stable self-adhesiveness in a wide humidity range. In detail, an adhesive conductive gel containing an electrolyte and adhesive composition is exemplified; the adhesive composition comprises a gel comprising a cross-linked copolymer of a compound represented by the following general formula (1)

Formula 1

(wherein R₁ represents hydrogen or methyl group; R₂ represents methyl group or ethyl group; and n represents an integer of 2 to 12) or a mixture thereof and an unsaturated carboxylic acid, partially neutralized or not neutralized, and a compound represented by the following general formula (2)

Formula 2

(wherein R₃ represents methyl group or ethyl group; and m represents an integer of 8 to 30) or a mixture thereof, and water. As the compound of the above general formula (1), a mixture with n=4 in average is desirable. The unsaturated carboxylic acid is preferably acrylic acid. To use as the conductive gel 17, a halide (alkali halide) of an alkali metal such as lithium chloride, sodium chloride, potassium chloride, or the like is contained in the above pressure sensitive adhesive composition as an electrolyte to make the composition conductive. It is desirable, to adjust hygroscopicity, that a polyvalent alcohol such as glycerin, propylene glycol, or a moisturizing ingredient such as lactic acid, urea, hyaluronic acid is added in addition to alkoxypolyethylene glycol. Additives such as perfume, a coloring agent, and a medicinal properties may also be added. A method for producing this pressure sensitive adhesive composition includes a method for performing cross-linking copolymerization in the mixture of
(a) a compound represented by the following general formula (1),

Formula 3

(wherein R₁representshydrogen or methyl group; R₂ represents methyl group or ethyl group; and n represents an integer of 2 to 12) and
(b) an unsaturated carboxylic acid monomer,
(c) a polyfunctional unsaturated organic compound containing a plurality of radical polymerizable groups, and
(d) an alkaline compound,
in a mixture of
(e) a mixture of a compound represented by the following general formula (2),

Formula. 4

(wherein R₃ represents methyl group or ethyl group; and m represents an integer of 8 to 30), and
(f) water. In the method for producing the above pressure sensitive adhesive composition, when preparing the raw material mixture to be cross-linking copolymerized, it is desirable to decrease influence of containment of impurities on performance of pressure sensitive adhesives formed, by maintaining the compound of the general formula (1) and the compound of the general formula (2) under the condition of presence of an alkaline compound, and thus decreasing content of impurities, which are the polyfunctional compounds contained in the compound of the general formula (1). It is exemplified that conductive gel with adhesiveness is obtained by: mixing water, a polymerization inhibitor, a polymerizable monomer (for example, the compounds of the above general formulae (1) and (2) etc.), a pH adjuster using amino alcohol, which has also a role of a conductive substance, and a cross-linking agent; adding a polymerization initiator; performing a polymerization reaction; and adjusting pH at 8 to 13. Reason for using amino alcohol as the above pH adjuster is that: in the case of using sodium hydroxide as the pH adjuster for example, the conductive gel 17 changes pH at the vicinity of the aluminum element 15 to alkaline, caused by electrolysis of a sodium ion and hydrolysis, however, amino alcohol does not hydrolyze and thus does not cause pH change. And, the aluminum element 15 provides more stable potential when the conductive gel 17 is in an alkaline state as compared with an acidic state. Therefore, it is desirable that the conductive gel 17 is used under a pH of 8 or higher, and in consideration of influence on skin, a pH of 13 or lower. As the conductive gel 17 with self-adhesiveness, having skin compatibility, already commercialized products may also be used, for example, RG-63B conductive hydrogel commercialized by kendall-LTP division of Tyco Healthcare Group LD, Mansfield, Massachusetts, and a conductive gel produced by the LecTec Corporation of Minnetonka, Minnesota (gel disclosed in USP No. 4,979,517) may also be used. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

A method for pasting the conductive gel 17 onto the substrate tape 14 and the aluminum element 15 is not especially limited, and for example, the conductive gel 17 (or a precursor composition thereof) may be applied and formed (or polymerized) on the aluminum element 15 (a part of the substrate tape 14 may be further included) after fixing the substrate tape 14, the aluminum element 15 and the cable 16. Alternatively, another method can be used, the method may comprise: after fixing the substrate tape 14, the aluminum element 15 and the cable 16, overlapping and pasting the conductive gel 17 formed on a releasing film, onto the aluminum element 15 (a part of the substrate tape 14 may be further included); and peeling the a releasing film. However, any method other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Thickness of the conductive gel 17 may be in a range of about 0.5 to 2 mm or any as long as it provides sufficient adhesiveness strength onto the body surface (skin), and electric conductivity to flow current to the body surface (skin) through the conductive gel 17 from the cable 16 and the aluminum element 15. However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Shape (form) of the conductive gel 17 is not especially limited, however, a rectangular shape rounded at the four corners, as shown in Fig. 1, is a generally used shape. However, the conductive gel 17, as shown in Fig. 1, has a cut out U shape (concave), which is slightly larger than a portion including the position of the fastener 16b so as not to directly contact with the fastener 16b of the tip of the cable 16, at the end of the shorter side of the rectangle. However, any shape other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Size (size of the rectangle rounded at the four corners) of the conductive gel 17 may be about 11 (plus or minus 3) cm x 10 (plus or minus 3) cm, which is usually used, or any as long as the size is slightly smaller than that of the substrate tape 14, and slightly larger than that of the aluminum element 15. However, any shape other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. Size of cut out of U(concave) shape at the end of the shorter side of the rectangular conductive gel 17 may be about 5 (plus or minus 1) cm x 3 (plus or minus 1) cm as long as it is slightly larger than that of a fastener bob. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

(7) The cover tape 18
The cover tape 18 is provided to prevent the aluminum element 15 and the cable 16 from direct contact to skin (body surface) of human or animal. That is, most part of the surface side (an opposite side from the surface attached to the body surface) of the aluminum element 15 is covered with the conductive gel 17, so as to provide a structure that inhibits direct contact to skin (body surface) of human or animal. However, as shown in Fig. 1, the end of shorter side of the rectangular conductive gel 17 has a cut out of U (concave) shape, which could provide direct contact of the conductive fastener bob of the tip of the aluminum element 15 and the conductive cable 16 in this cut out portion, to skin (body surface) of human or animal (large current flows onto the body surface through the relevant conductor having small area=causing scorch or burn of skin contacting to the relevant conductor). Accordingly, the cover tape 18 is provided so as to cover the portion cut out in U (concave) shape of the conductive gel 17 with an insulating material, as well as to attach the insulating material to the body surface also.

The cover tape 18 is usually composed of an insulating cover tape substrate 18a, which is slightly larger than the cut out in U (concave) shape of the conductive gel 17, an adhesive layer 18b formed on the surface (surface side adhered to the substrate tape body 14b) of said cover tape substrate 18a, and an pressure sensitive adhesive layer 18b, formed on the rear surface (surface side attached to the body surface) of the cover tape substrate 18a.

The cover tape substrate 18a is any enough if it has insulation function (role) for the conductive aluminum element 15 and the conductive cable 16 to prevent from direct contact to skin (body surface) of human or animal and electric shock. Accordingly, such material and thickness to exert the insulation function (role) sufficiently may be enough.

A material of the cover tape substrate 18a is not especially limited, as long as it provides the insulating function, and a conventionally known one such as polyethylene (PE), polyethylene terephthalate (PET) may be utilized. In particular, it is desirable to be formed by such an expandable material having high insulating property, flexibility and cushioning property, such as polyethylene foam or the like, similarly as the substrate body 14b, so that the whole surface of the conductive gel 17 with self-adhesiveness enables to closely adhere (pressure sensitively adhere) to skin (body surface). However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Thickness of the cover tape substrate 18a is desirably thin as long as it maintains insulating property, has flexibility (cushioning property) and is expandable, so that the whole surface of the conductive gel 17 with self-adhesiveness enables to closely adhere to skin (body surface). It may be enough to be in a range of about 0.5 to 2 mm. However, even the cases outside the above range, it may be applicable sufficiently as long as it doesn't impair the effects of the present invention.

A material of the adhesive layer 18b is not especially limited, and conventionally known various kinds of pressure sensitive adhesives can be utilized, similarly as adhesives in the adhesive layer 11b. Pressure sensitive adhesives based on natural rubber, acrylic based or urethane based pressure sensitive adhesives may be exemplified. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. Acrylic based pressure sensitive adhesives or the like is preferable, which enables to adhere firmly between the cover tape substrate 18a and the substrate tape body 14b (both are insulating resin materials, in particular, between polyethylene foams).

Thickness of the adhesive layer 18b is any if it exerts sufficient adhesive strength between the cover tape substrate 18a and the substrate tape body 14b (both are insulating resin materials, in particular, between polyethylene foams). However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

A material of the pressure-sensitive adhesive layer 18c is not especially limited, however, it is desirable to use similar pressure sensitive adhesives as the adhesive layer 14c, and conventionally known various kinds of pressure sensitive adhesives may be available. Pressure sensitive adhesives based on natural rubber, acrylic based or urethane based pressure sensitive adhesives may be exemplified. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention. Acrylic based pressure sensitive adhesives or the like is preferable, because, they have sufficient adhesiveness strength to body surface (skin) and enables to be peeled easily from body surface (skin) after use. As for the adhesive layer 18b and the pressure-sensitive adhesive layer 18c, such adhesives should be selected that: adhesive strength to the substrate tape body 14b side by the adhesive layer 18b is sufficiently stronger than that to the body surface (skin) by the pressure-sensitive adhesive layer 18c, and in peeling from the body surface (skin) after use, adhesive surface between the substrate tape body 14b and the cover tape substrate 18a is not separated.

Thickness of the pressure-sensitive adhesive layer 18c may be enough to be in a range of about 0.5 to 40 um (micrometer) as long as it provides sufficient adhesiveness strength to body surface (skin). However, even the cases outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Form (shape) of the cover tape 18 is not especially limited, however, as shown in Fig. 1, the one having saddle shape (triangle or triangle with rounded three corners) rounded at the three corners, having slightly larger than a portion where the conductive gel 17 is cut out in U (concave) shape is generally used. However, any form other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Size of the cover tape 18 may be a saddle shape rounded at the three corners having about a size of a bottom side of 8 (plus or minus 1) cm x a height of 4 (plus or minus 1) cm, which is usually used, as long as it is slightly larger than a portion where the conductive gel 17 was cut out in U (concave) shape, is used. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

(8) The release sheet 19
The release sheet 19 is provided to protect an adhesive surface before use. The adhesive face before use contains the conductive gel 17 with self-adhesiveness (the whole surface), an adhesive surface of the substrate tape 14 at the exterior peripheral of the gel and an adhesive surface of the cover tape 18 (that is, the adhesive layer 14c, the conductive gel 17 with self-adhesiveness and the pressure-sensitive adhesive layer 18c) provided at a portion where the conductive gel 17 was cut out in U (concave) shape.

A material of the release sheet 19 may be any material as long as it prevents oxygen molecule or water molecule from penetrating through the release sheet 19, thereby prevents deterioration of the adhesive surface during storage to protect the adhesive surface before use, and it has flexibility so as to provide close adhesion with the adhesive surface before use, and it can be peeled easily just before use. Conventionally known various kinds of release sheet materials may be utilized. Polyethylene (PE), polyethylene terephthalate (PET) and paper, and the like are exemplified. However, any material other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Thickness of the release sheet 19 is not especially limited, however, it is enough to be in a range of about 10 to 125 um (micrometer). However, even the case outside the above range may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Form (shape) of release sheet 19 is not especially limited, and as shown in Fig. 1, it may be a rectangle rounded at the four corners, having fundamentally the same shape as the substrate tape 14, so as to cover the conductive gel 17 with self-adhesiveness (the whole surface), the adhesive surface of the substrate tape 14 at the exterior peripheral of the gel, and the adhesive surface (that is, the adhesive layer 14c, the conductive gel 17 with self-adhesiveness and the rear pressure-sensitive adhesive layer 18c) of the cover tape 18 provided at a portion where the conductive gel 17 was cut out in U (concave) shape. However, it is desirable that it has a protruding portion 19a from the substrate tape 14, so as to make partial detaching easy. However, any form other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Size of the release sheet 19 may be a rectangular shape rounded at the four corners with a size of about 13 (plus or minus 3) cm x 11 (plus or minus 3) cm as long as fundamentally it is slightly larger than that of the substrate tape 14. When it has the protruding portion 19a from the substrate tape 14 to make peeling easy as a part of the release sheet 19, and a size thereof is about 1 (plus or minus 1) cm x 3 (plus or minus 1) cm, it is convenient to hold it in peeling. However, any size other than exemplified in the above may be applicable sufficiently as long as it doesn't impair the effect(s) of the present invention.

Explanation is given above on a disposable pad electrode to be used for various defibrillators (for example, an external defibrillator, a semi-automated defibrillator, an Automated External Defibrillator (AED) and the like), as one embodiment of the bio-electrode of the present invention. However, the bio-electrode of the present invention is not especially limited to these, and is applicable as the bio-electrode having X-ray transmission, to a transcutaneous pacing electrode; an electrocardiogram electrode; or a return electrode or the like, to be used in various defibrillators (for example a defibrillator provided with pacing function, other than defibrillation function, or the like). Among these, a defibrillation electrode; a transcutaneous pacing electrode; an electrocardiogram electrode can be communized and the above defibrillation electrode (a disposable pad electrode) can be used. The bio-electrode of the present invention may also be available as a multifunctional electrode wherein a defibrillation electrode, a transcutaneous pacing electrode and an electrocardiogram monitoring electrode are consolidated as one electrode. In this case, it is necessary to use the conductive gel which contains a chloride ion (for example, lithium chloride, sodium chloride, potassium chloride, or the like). Because, presence of a passive film at the surface of an aluminum element inhibits transcutaneous pacing, however, by containing a chloride ion, the passive film can be destroyed, thus enabling transcutaneous pacing for 60 minutes or more. On the other hand, in the case of using conductive gel not containing a chloride ion, pacing is impossible after about 5 minutes.

A defibrillator which a doctor uses in a hospital has various functions other than defibrillation function, and it is called a defibrillator provided with pacing function, a manual-type defibrillator or the like. As an electrode to be used in such a defibrillator, a defibrillation electrode (a disposable pad electrode), a transcutaneous pacing electrode, and an electrocardiogram electrode are included. Among these, a defibrillation electrode (a disposable pad electrode) is as described above.

A transcutaneous pacing electrode is the one which is used for extreme bradycardia in healthcare settings, during a period till a pacemaker is prepared, by attaching the transcutaneous pacing electrode (usually having the same configuration as in the disposable pad electrode 10) onto the body surface, usually at a left flank and a breast (usually right breast for an adult male, and the center of the breast for a child or a female), to flow electric current of about 100 mA therefrom, so as to forcibly shrink a heart.

The above electrocardiogram electrode is used, in a hospital or in an ambulance or outdoors, with a defibrillator equipped with electrocardiogram analysis function, by attaching the electrocardiogram electrode (usually having the same configuration as in the disposable pad electrode 10) at the left flank and a breast of a patient, and by pushing an analysis button of the defibrillator, to perform analysis of an electrocardiogram by an electrocardiogram analysis device inside the defibrillator. When the device calculates defibrillation necessary, it is noticed by a sound or a voice for an operator (doctor or an emergency medical technician) to perform defibrillation by pushing a shock button.

The above return electrode is an electrode to be used at one side of an electrosurgical knife (an electrosurgical unit). In detail, in surgery using the electrosurgical knife, high frequency current is passed through a living body, using a return electrode (usually it may have the same configuration as in the disposable pad electrode 10, however, the external device is a high frequency power source and not a defibrillator) attached in a relatively wide contact area (mainly at the rear side from an operation site sandwiching a living body, such as the flank or the back of the patient) relative to a living body; and a metallic electrode called an electrosurgical knife tip electrode (an active electrode), as a pair. Thereby, heat is not generated at the return electrode side in which contact resistance is small and flowing current density is low, while, at the electrosurgical knife tip electrode having a certain degree of contact resistance and high current density, heat is generated by Joule heat or arc discharge. This heat instantaneously heats cells, causing explosion/dissipation of the cells and incision/coagulation action. In this way, the return electrode is the same as other external defibrillation electrode; a transcutaneous pacing electrode; an electrocardiogram electrode or the like, in view of the use by being attached on the body surface in surgery using the electrosurgical knife (an electrosurgical unit). However, as for size of the electrode, as described above, it is general that the return electrode with a larger size as compared with other electrodes is used.

Fig. 3A is a schematic drawing schematically showing a return electrode to be used for one side of an electrosurgical knife, as one embodiment of the bio-electrode of the present invention. Fig. 3B is a cross-sectional view along the A-A line of Fig. 3A. As shown in Figs. 3A, 3B, the return electrode 30 is composed of a pair of the bilateral electrode element (aluminum element) 15 provided on the substrate tape 14, and a part of each is formed so as to protrude from the substrate tape 14. On the electrode element (aluminum element) 15, the conductive gel 17 is formed (here, the conductive gel 17 is provided so as not to protrude from the electrode element (aluminum element) 15). The electrode element (aluminum element) 15 at a portion each protruding from the substrate tape 14 is attached with a clip 16d, provided at the tip of the cable 16, thus providing an electrically connected structure. The other end of the cable 16 has an electrically connected structure to a high frequency power source (not shown, refer to Fig. 2), which is an external device, directly or via a connector. Here, the clip 16d is not especially limited, as long as it is electrically conductive (conductor), and for example, SUS, Al or the like may be used. It is desirable that the release sheet 19 (not shown) is provided on the conductive gel 17 to prevent drying till before use. At the electrode element (aluminum element) 15 of a portion protruded from the substrate tape 14, the backing material (reinforcing material) 15b (not shown) may be provided, or only a portion of the electrode element (aluminum element) 15 of the protruded part may be reinforced by thickening.

The bio-electrode of the present invention has the following advantages:
(1) It has the following advantages compared with the bio-electrode using conventional tin as an electrode element.

(a) It is X-ray transmissive. A conventional bio-electrode using tin does not transmit X-rays, therefore for X-ray photographing in a catheter room or the like, it was necessary to once remove the bio-electrode attached on a patient. Therefore, it wasn't possible to monitor an electrocardiogram, monitor waveform of ventricular fibrillation of a patient and monitor SpO₂, ETCO₂ or the like, through the bio-electrode, during inspection (treatment, medical care, medical examination, and diagnosis) in X-ray CT in the catheter room or the like. On the other hand, because the X-ray transmissive bio-electrode of the present invention does not interfere X-ray transmittance (enables to monitor heart condition), even in the attached state of the bio-electrode to a patient, X-ray photographing of the catheter room or the like is possible. It is superior in that an electrocardiogram, waveform of ventricular fibrillation of a patient and SpO₂, ETCO₂ or the like can be monitored meanwhile. Furthermore, the X-ray transmissive bio-electrode is superior in that surgery is possible while monitoring a condition of a heart with X-rays by attaching the bio-electrode in advance, even in implanting a pacemaker.

(b) It is not necessary to take measures against discoloring of conductive gel caused by a tin oxide. Therefore, it is not necessary to include a deoxidant (for example, Ageless (registered trade name)) in packaging to prevent discoloring caused of oxygen penetration through a packaging (wrapping) material. Sealing of a cable is not necessary to prevent the cable from influence (flowing of oxygen inside a coating material) of tin oxide added in the bio-electrode.

(2) It has the following advantages compared with a bio-electrode using a sheet (carbon sheet) kneaded with a carbon fiber in an existing resin, as an electrode element.

(a) An element made of carbon to be used in an electrode element had a problem of high cost. The aluminum element 15 of the present invention has advantage of attaining extremely low cost as compared with the carbon element.

(b) A carbon sheet alone cannot exert performance as the bio-electrode for a defibrillator or the like (= electric performance cannot be maintained for 24 months), therefore there are many products coated with silver-silver chloride or manganese dioxide, however, they had a problem of still more increasing cost. There is quite a few number of conductive gel utilizable to the element made of carbon, as well as it is likely to deteriorate by drying, therefore, it has a large quantity of sonant marks (dried-up points) after passing 24 months, which is a usual guarantee period. In addition, the conductive gel reacts with silver-silver chloride or manganese dioxide, deteriorates by dissolution etc. of conductive gel, thus the element cannot exhibit electrode performance sufficiently. The aluminum element 15 of the present invention has advantage of no necessity of coating of silver-silver chloride or manganese dioxide, and production in low cost. Since no limitation of conductive gel which can be used, and arbitrary selection of the gel resistant against drying is possible among many conventionally known conductive gels, therefore there are not present sonant marks (dried-up portions) at all after passing 24 months, which is a usual guarantee period, and sufficient electrode performance can be exhibited.

(3) It has the following advantages compared with a bio-electrode using an Al foil, as the electrode element.

(a) The Al foil, which is an electrode element, has a problem of practical use due to corrosion caused by contact with conductive gel, which is a component member of the bio-electrode. For example, in the case of using as a transcutaneous pacing electrode, it is required to endure usually for about 60 minutes or so, however, it endures less than 5 minutes due to generation of gas at the surface of a passive film. On the other hand, the aluminum element 15 of the present invention has advantage that the aluminum element as the electrode element is little subjected to corrosion caused by contact with the conductive gel, and corrosion and sonant marks are not observed even after passing 24 months, which is a storage period of a product, as well as discoloring of the conductive gel is not observed. Still more, it has advantage of being endurable for 60 minutes or more, even in using as the transcutaneous pacing electrode.

Examples

(Example 1)
The following experiment was performed using a disposable pad electrode 10 having a configuration shown in Fig. 1.

As components of the pad electrode 10, synthetic paper with a thickness of 110 um (micrometer) was used for the sheet substrate 11a, and acrylic pressure sensitive adhesives with a thickness of 30 um (micrometer) was used for the adhesive layer 11b to provide the circular shaped label 11 with a diameter of 3 cm.

As the rivet 12, SUS430 with a diameter of 3 mm was used to caulk.

As for the

ring washers

13a, 13b each, SUS430 with an inner diameter of 3.2 mm and an outer diameter of 11 mm was used.

As for the substrate tape 14, polyethylene foam with a thickness of 1 mm was used for the substrate tape body 14b, and acrylic based pressure sensitive adhesives with a thickness of 30 um (micrometer) was used for the adhesive layer 14c.

As for the aluminum element 15, a thin film of Al alloy (an aluminum foil (trade name: Alnoble ZR-N), manufactured by Toyo Aluminum K.K.), in which the Al alloy contained Mn, the remaining part was composed of Al and impurities and the impurities included Mg, Si, Cu, Fe and Zn, was used.

As for the cable 16, a Cu wire coated with tin plating was used as the cable body 16c; brass was used for the fastener 16b having the through hole 16c at the tip; and the other tip was connected to an external device (defibrillator body) 20.

As for the cover tape 18, polyethylene foam with a thickness of 1 mm was used for the cover tape substrate 18a, acrylic based pressure sensitive adhesives with a thickness of 30 um (micrometer) was used for the front face adhesive layer 18b and acrylic based pressure sensitive adhesives with a thickness of 30 um (micrometer) was used for the rear face adhesive layer 18b.

As for the release sheet 19, polyethylene terephthalate (PET) with a thickness of 75 um (micrometer) was used.

The pad electrode 10 was assembled using the above components, firstly by pasting the substrate tape 14 and the aluminum element15 in a state that the positions of the through holes 14a and 15a overlapped together. Next, the

ring washers

13a, 13b were put on both sides of through holes 14a, 15a, and, the fastener 16b was put on the ring washers 13b. Then, the rivet 12 was inserted into the ring washer 13a, the through holes 14a, 15a, the ring washer 13b, and the fastener 16b, and was caulked to fix them. The label 11 was adhered so that the rivet 12 and the ring washer 13a are not exposed. Next, the conductive gel 17 having self-adhesiveness was coated on the surface of the aluminum element 15 (including the substrate tape 14 of the exterior peripheral of the aluminum element 15) so as to attain a predetermined thickness. In this case, as shown in Fig. 1, after masking a certain portion including cable 16 so as to prevent the conductive gel 17 from contacting to the cable 16, the conductive gel 17 was coated on, then, by removing the masking, the cover tape 18 was pasted on the portion. Lastly, the release sheet 19 was pasted on the surface of the conductive gel 17 (including the cover tape 18) to complete assembly (preparation) of the pad electrode 10.
(Example 2)

The pad electrode 10 was prepared in the same way as Example 1, except that a thin film of another Al alloy (an aluminum foil (trade name: Alnoble ZR-S), produced by Toyo Aluminum K.K.), in which the Al alloy contained Mn, the remaining part was composed of Al and impurities and the impurities included Mg, Si, Cu, Fe and Zn was used instead of the thin film of Al alloy of Example 1, as the aluminum element 15.
(Comparative Example 1)

The pad electrode 10 was prepared in the same way as Example 1, except that an electrode element using tin foil with a thickness of 75 um (micrometer) and conductive gel containing tin chloride were used, instead of the aluminum element 15.
(Comparative Example 2)

The pad electrode 10 was prepared in the same way as Example 1, except that an electrode element using a carbon sheet with a thickness of 100 um (micrometer), coated with silver-silver chloride, was used, instead of the aluminum element 15.
(Comparative Example 3)

The pad electrode 10 was prepared in the same way as Example 1, except that an Al foil (purity of 99.9%) was used, instead of the aluminum element 15.

<Tests>
(1) X-ray transmittance test
Using the pad electrodes 10 prepared in Examples and Comparative Examples, X-ray photographing was performed in a catheter room to confirm X-ray transmission.

As a result of the above test, it was confirmed that the samples of Examples 1 to 3 transmitted X-rays, excluding the fixation member or cable using metal. On the other hand, in Comparative Example 1, it was confirmed that X-rays do not transmit (all electrode portions were photographed in white), because tin was used for the electrode element. Also in the samples of Comparative Examples 2 and 3, it was confirmed that they transmitted X-rays, excluding the fixation member or cable using metal.

(2) High temperature test (accelerated life-time test)
After maintaining the pad electrodes 10 prepared in Examples and Comparative Examples in high temperature (50 degrees celsius) for three months (an accelerated life-time corresponding to the condition of storage at room temperature for 24 months, which is almost product guaranteed period), the electrode elements were observed.

As a result of the above test, there was no change observed in the samples of Examples 1 to 3. On the other hand, in Comparative Example 1, rusting (corrosion) of tin and discoloring of gel were observed. Also in Comparative Example 2, although rare conductive gel, which could be used with the element made of carbon was used, a large quantity of sonant marks were observed after the high temperature test because the conductive gel was deteriorated by drying. Also in Comparative Example 3, many corrosion caused by dissolution of the Al foil were observed after the high temperature test.

(3) Performance test of a defibrillation electrode
By using the pad electrode 10 prepared in each Examples and Comparative Examples, after the high temperature test of the above (2), it was tested whether they function sufficiently as the defibrillation electrode.

As a result of the above test, for the samples of Examples 1 to 3, it was confirmed that they exhibited performance sufficiently as the pad electrode 10 when attaching the pad electrode 10 to the surface of a dummy doll and applying current from a defibrillator. Because the conductive gel 17 does not use a salt component in high concentration, no problem of cytotoxicity raised. On the other hand, Comparative Examples 1 to 3 were not able to function sufficiently as the defibrillation electrode.

(DISCUSSION)
Comparative Example 2 had a problem of increased cost of the carbon element used for the electrode element. It required coating of silver-silver chloride to cover inferior performance as the defibrillation electrode by carbon alone, resulting in further increased cost. In addition, quite a few number of conductive gel adaptable to the element using carbon. Further, they can be deteriorated by drying, therefore, a large quantity of sonant marks (dried-up points) were observed after the high temperature test (the acceleration life-time test). The conductive gel can be also deteriorated by reacting with silver-silver chloride or manganese dioxide, dissolving itself, thus it cannot exhibit electrode performance sufficiently.

It is confirmed that Comparative Example 3 could not serve for practical use due to corrosion of the Al foil as the electrode element.

The present application is based on Japanese Patent Application No. 2012-064496, filed on March 21, 2012 and the content of which is hereby incorporated by reference in its entirety into this application.

EXPLANATION OF REFERENCE NUMERALS

10 disposable pad electrode (disposable electrode), which is one of the bio-electrode
11 label
11a sheet substrate
11b adhesive layer
12 rivet
13a, 13b ring washer
14 substrate tape
14a through hole for a rivet
14b substrate tape body
14c adhesive layer
15 electrode element (aluminum element)
15a through hole
15b backing material (reinforcing material)
16 cable
16a cable body
16b fastener
16c through hole
16d clip
17 conductive gel
18 cover tape
18a cover tape substrate
18b adhesive layer
18c pressure-sensitive adhesive layer
19 release sheet
19a protruding portion
20 defibrillator body as an external device
21 patient
22 another cable connected to the defibrillator body
23a connector of the tip of a cable of the defibrillator body
23b connector of the tip of a cable of the disposable pad electrode
30 return electrode

Claims

A bio-electrode comprising:
conductive gel;
an electrode element;
a cable for electrically connecting the bio-electrode and an external device;
wherein the electrode element is a thin film formed by using an Al alloy which transmits X-rays and has corrosion resistance against the conductive gel.
The bio-electrode according to claim 1, wherein the Al alloy contains Mn.
The bio-electrode according to claim 1 or 2, wherein the Al alloy contains Mn, and a content of the Mn is in a range of 0.1 to 6% by mass.
The bio-electrode according to any one of claims 1 to 3, wherein
the Al alloy contains Mn, the remaining part being composed of Al and impurities, and having at least one of Mg, Si, Cu, Fe and Zn in the impurities, and
a content of the Mn is in a range of 0.1 to 6% by mass.
The bio-electrode according to any one of claims 1 to 4, wherein
the Al alloy contains Mn, the remaining part being composed of Al and impurities,
a content of the Mn is in a range of 0.1 to 6% by mass,
the impurities contain at least one of Mg, Si, Cu, Fe and Zn, and
a content of Mg, Si, Cu, Fe and Zn in the impurities is 0.03% by mass or less, respectively.
The bio-electrode according to any one of claims 1 to 5, wherein
the Al alloy contains Mn, the remaining part being composed of Al and impurities,
a content of the Mn is in a range of 0.1 to 6% by mass,
the impurities contain Mg, Si, Cu, Fe and Zn, and
a content of Mg, Si, Cu, Fe and Zn in the impurities is each 0.03% by mass or less.
The bio-electrode according to any one of claims 1 to 3, wherein
the Al alloy contains Mn and Mg, and
a content of the Mn and the Mg is each in a range of 0.1 to 6% by mass.
The bio-electrode according to any one of claims 1 to 3 and 7, wherein
the Al alloy contains Mn and Mg, the remaining part being composed of Al and impurities, and
the impurities contain at least one of Si, Cu, Fe and Zn, and
a content of Mn and Mg is in a range of 0.1 to 6% by mass, respectively.
The bio-electrode according to any one of claims 1 to 3 and 7 to 8, wherein
the Al alloy contains Mn and Mg, the remaining part being composed of Al and impurities,
a content of the Mn and the Mg is in a range of 0.1 to 6% by mass, respectively,
the impurities contain at least one of Si, Cu, Fe and Zn, and
a content of Si, Cu, Fe and Zn in the impurities is 0.03% by mass or less, respectively.
The bio-electrode according to any one of claims 1 to 5, wherein
the Al alloy contains Mn and Mg, the remaining part being composed of Al and impurities,
a content of the Mn and the Mg is in a range of 0.1 to 6% by mass, respectively,
the impurities contain Si, Cu, Fe and Zn, and
a content of Si, Cu, Fe and Zn in the impurities is 0.03% by mass or less, respectively.
The bio-electrode according to any one of claims 1 to 10, wherein the electrode element is a thin film, having a thickness of 9 to 200 um (micrometer), formed by using the Al alloy.
The bio-electrode according to any one of claims 1 to 11, which is any of a defibrillation electrode, a transcutaneous pacing electrode, an electrocardiogram electrode, a multifunctional electrode in which defibrillation function, transcutaneous pacing function and electrocardiogram monitoring function are consolidated as one electrode, or a return electrode.