JPS61159938A - Electrode for living body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention detects electrical signals generated from within the body, such as cardiac potential and myoelectric potential, by applying the adhesive to the surface of a living body (hereinafter referred to as skin). Regarding biological electrodes for guiding electrical signals to external diagnostic equipment, or for introducing electrical signals generated from external electrical therapy devices such as low frequency waves into the body through the skin, in detail, they can be stored compactly in a moisture-free state, It can be transported], and when used, it quickly swells into the shape it will be used in just by absorbing water, and has good adhesion to the skin, excellent conductivity, and is capable of conducting stable electrical signals for long periods of time. It provides electrodes.

<Prior art> In recent years, in the medical field, in order to perform appropriate disease treatment, electrical signals such as electrocardiograms, electromyograms, and electroencephalograms have been measured, and low frequency waves have been transmitted into the body to perform electrical treatment. As the number of cases increases, biological electrodes, which serve as media between the skin and external devices, play an important role.
There is.

Conventionally, these biological electrodes have been made by molding conductive metals such as silver, aluminum, tin, nickel, etc. into relatively thin flat plates, and in order to further improve the adhesion with the skin, the above flat plates have been used. Conductive creams or pastes are used to coat the surfaces of objects, but they do not adhere well to the skin, making the process of applying the creams or pastes complicated, and contaminating the hands and the skin surface to which they are applied. It had drawbacks.

was.

On the other hand, gel-like electrodes have been developed to improve adhesion and make them easier to attach to the skin, but since these electrodes contain water as a conductive substance, it is difficult to prevent moisture from scattering during storage. In addition, there are various problems such as gel breakage during storage and transportation due to lack of mechanical strength due to the hydrogel state. Furthermore, since it contains water, there is a possibility that mold or the like may grow due to the contamination of various germs, so a thorough sterilization process is required.

<Problems to be Solved by the Invention> The present invention solves the problems described above, such as the poor adhesion of conventional biological electrodes during long-term attachment, and the mechanical problems common to biological electrodes containing water. The purpose of this invention is to provide a biological electrode that overcomes problems such as lack of strength.

Another object is to provide a biomedical electrode that takes up as little bulk as possible during storage and transportation, and is easy to operate during use.

Means for Solving the Problems> As a result of intensive studies in view of the various problems mentioned above, the present inventors have discovered a specific conductive substance that can reversibly swell and contract with water. The inventors have discovered that a scale can function as a biological electrode simply by forming a dry biological electrode from a functional polymeric material and supplying water before use, leading to the present invention.

That is, the present invention is made of a polymeric material that reversibly swells or contracts due to water absorption and dehydration and maintains rubber elasticity even after swelling, and is constructed in a dry state. The molecular material is a crosslinked product of polyacrylic acid or its salt,
Alternatively, the present invention relates to a biological electrode made of a hydrophilic urethane polymer.

The polymeric material used in the present invention forms the base material of the bioelectrode, and is usually kept under dry conditions to reduce hypertonicity, but after absorbing water, it rapidly swells and becomes difficult to use during use. It all comes down to shape. In addition, in terms of shape retention, it has rubber elasticity before and after swelling, so it has high mechanical strength and can adhere to the shape of the skin to which it is applied.

An example of a polymer material having such properties is a crosslinked product of polyacrylic acid or a salt thereof. Salts of alkaline earth metals and ammonium salts crosslinked with a crosslinking agent such as metal oxides, metal salts, and compounds having at least two epoxy groups in the molecule are used.

Another example is a hydrophilic urethane polymer that is a condensation product of a hydrophilic urethane prepolymer. Such hydrophilic urethane prepolymers are exemplified by those consisting of polyolefin oxide units having two or more hydroxyl groups at the terminals, but they are good in terms of water absorption swelling properties and rubber elasticity after water absorption.

Preferably, a polyisocyanate compound containing at least 50% by weight of polyethylene oxide units having a polyol moiety is used. It is desirable to introduce it at a concentration of ~20% by weight.

The above prepolymers have high reactivity because they contain isocyanate groups, and undergo a condensation reaction using diamines such as ethylenediamine and hexamethylenediamine, polyamines such as diethylenetriamine, water, etc. as a medium, and are polymerized. The resulting polymer swells due to water absorption and maintains rubber elasticity even after swelling, becoming a so-called water-absorbing rubber.

These polymeric materials have superior mechanical strength compared to what is generally called a water-absorbing polymer, which absorbs several hundred times more water than its own weight, and usually absorbs less than 10 times its own weight within a few minutes after being immersed in water. , preferably has a saturation allowable water absorption amount of 5 times or less.

The biological electrode of the present invention will be specifically explained using the drawings.

Figure 1 is a cross-sectional view of a biomedical electrode molded to be attached to a suction-type electrode jig, and Figure 2 is a cross-sectional view of the biomedical electrode attached to the jig after absorbing water. . Reference numeral 1 is an electrode made of a polymer material that swells due to water absorption and maintains rubber elasticity even after swelling, and is formed into an arm shape that can be attached to a suction type electrode jig consisting of a metal part 2 and a suction rubber 3. It is what was done.

FIGS. 3 and 4 show a perspective view of a biomedical electrode molded so as to be attached to a clip-on electrode jig, and a perspective view of the biomedical electrode in an attached state after absorbing water.

FIGS. 5 and 6 are cross-sectional views of a biomedical electrode molded to be attached to a hook-type electrode jig, and after absorbing water, the biomedical electrode is fixed with an adhesive sheet 4 for fixing on the skin surface.
A sectional view of the installed state is shown.

The biological electrode of the present invention swells appropriately due to water absorption and exhibits conductivity, and can be formed into the various shapes or sheet shapes described above to improve its adhesion to the skin. Furthermore, in order to more quickly absorb water, it is preferable to foam the base material of the bioelectrode before or during molding to form a foam, and both closed-cell and open-cell foams can be used.

The bioelectrode of the present invention uses water as a conductive substance during use, but it is chlorinated in advance to further improve conductivity)
Additives such as IJum, various electrolytes such as potassium chloride, water retention agents such as polyhydric alcohols such as glycerin, fillers, colorants, antifungal agents, and surfactants are added to impart various functions. You can also do it.

<Effects of the Invention> As described above, since the biological electrode of the present invention is normally stored in a dry state, it is not bulky and compact, and quickly swells when brought into contact with water. Since it exhibits electrical conductivity and has rubber elasticity, it has excellent mechanical strength, good skin adhesion, and is easy to handle.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these in any way and includes various modifications.

Example 1 Polyoxyalkyl (allyl) sulfate ammonium salt 21 and glycerin IP were mixed with 7 PK of water, and this mixture was added to 7.4 PK of hydrophilic urethane prepolymer heated to 40° C. with vigorous stirring. . Next, it was poured into a bowl-shaped mold and left to stand for several minutes to naturally harden, and after drying, it was molded into a bowl-shape as shown in FIG. 1 to obtain the bioelectrode of the present invention.

Example 2 Sodium polyacrylate (average degree of polymerization 10,000) 10Pt
/C,) 10 ml of liglycidyl isocyanurate to 10 ml of water
After dissolving the mixture in 2 and adding 9 solutions, it was cast into a 5 m thick sheet, and then heated and dried to form a crosslinked product to obtain the biological electrode of the present invention.

The biological electrodes obtained in each example had good water absorption, exhibited sufficient rubber elasticity even after water absorption, had high mechanical strength, and had good adhesion and electrical signal transmission when applied to the skin. Met.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of an example of the biological electrode of the present invention,
FIG. 2 shows a cross-sectional view of the device attached to the suction type electrode jig. 3 and 5 are perspective views and sectional views of other examples of the biological electrode of the present invention, and FIGS. 4 and 6 correspond to FIGS. 3 and 5, respectively, and the electrode jig is FIG. 3 is a perspective view and a cross-sectional view of the device attached to the device.

Claims (1)

[Claims] 1) It is composed of a polymeric material that reversibly swells or contracts due to water absorption and dehydration, and maintains rubber elasticity even after swelling, in a dry state, and the polymeric material is polyacrylic. A biological electrode made of either a crosslinked product of an acid or its salt, or a hydrophilic urethane polymer.