JPH0479254B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an electrolyte paste used when attaching an electrode for deriving a biopotential to a living body. (Prior Art) In order to derive the biopotential necessary for measuring electrocardiograms and electromyograms, electrode elements must be attached to the skin surface of the living body. Generally, this installation is
This is done by fixing electrode elements to the skin surface with adhesive tape, belts, etc. The skin surface is normally covered with an insulating layer called the stratum corneum, which is also covered with dirt and lipids. For this reason, it is necessary to create an electrically stable state by reducing the contact resistance between the electrode element and the skin. Furthermore, since the body surface is soft and uneven and expands and contracts in response to body movements, it is necessary to maintain a mechanically stable contact surface between the electrode element and the skin surface. To solve these problems, an electrolyte paste is used between the electrode element and the skin. Therefore, it is necessary for the electrolyte paste to have excellent electrical and mechanical properties as described above, and consideration must also be given to the living body, such as not giving stimulation to the living body. There are so-called biological electrodes that are attached to a living body by applying electrolyte paste to the skin surface or electrode surface immediately before use, and types that have an appropriate amount of electrolyte paste applied to the electrode surface in advance and are ready for use. There are two types: one that does not require the application of electrolyte paste and one that does not require the application of electrolyte paste. The former includes electroencephalogram electrodes and electrocardiogram test electrodes (for example, suction electrodes, limb electrodes, etc.) that are used repeatedly. The latter includes
Disposable electrodes that are mainly used only once and discarded after use (e.g. electrodes for electrocardiogram monitors for ICU/CCU,
Holter electrodes, etc.). The historical trend of such biological electrodes is that reusable electrodes first appeared, and then disposable electrodes appeared. Since electrolyte pastes are used in conjunction with biomedical electrodes, it is thought that electrolyte pastes will also advance accordingly. Therefore, first of all, an electrolyte paste is made that is easy to use for electrodes that are used repeatedly.
An electrolyte paste will then be created that is easy to use in disposable electrodes. However, since the history of disposable electrodes is short, the electrolyte paste for electrodes that can be used repeatedly as described above is currently used as the electrolyte paste. Since most of these electrolyte pastes must be stored in a container such as a tube, they have low viscosity and fluidity so that they can be easily extruded from the tube and applied to electrodes or the skin. Also, it is necessary to remove the electrolyte paste from the electrode after use.
Many are water-soluble because they can be wiped off or washed with water. Furthermore, it has a moderate amount of stickiness to help it blend into the skin. In consideration of such usage characteristics, adhesives have conventionally been made based on adhesives such as carboxymethyl cellulose and hydroxyethyl cellulose. (Problems to be Solved by the Invention) When such conventional electrolyte pastes are used, they tend to protrude around the electrodes, their viscosity decreases as body temperature rises, and even when they sweat, they tend to leak out from the sweat. It has the disadvantage that it mixes with other substances and tends to flow easily. For this reason, when an electrode is fixed using an adhesive tape, the adhesive strength of the adhesive tape decreases, causing the inconvenience that the electrode falls off. On the other hand, if the electrode is fixed using a suction cup or a belt, the reduced viscosity or easy flow of the electrolyte paste will not cause the electrode to fall off, but it will cause discomfort to the subject. The present invention was made in view of these conventional drawbacks, and its purpose is to provide an electrolyte paste that is easy to post-process, has no risk of leaching into the adhesive tape, and does not cause discomfort to subjects. That's true. [Structure of the Invention] (Means for Solving the Problems) The present invention is made by crosslinking polyvinyl alcohol with borate ions. (Function) The electrolyte paste of the present invention is a solid gel. Moreover, since it has low stickiness, it does not run out and is less sticky. (Example) Example 1 (Samples 1 to 3 in Table 1) Ion-exchanged water was added to polyvinyl alcohol (hereinafter referred to as PVA), potassium borate, and paraben, and the mixture was heated and dissolved. As shown in Samples 1 to 3 in Table 1, electrolyte pastes were prepared using samples containing different weight percentages of each component. In the table, the numbers of samples with good usage results are marked with a circle. Parabens and ion exchanged water are not shown in Table 1, but are added to both samples. % of parabens is 0.1 for each, % of ion exchange water is % of other ingredients
is the value obtained by subtracting the sum of 100 from 100 (the same applies to other examples). As shown in this table, good results were obtained for Sample 2. Sample 1 does not form a solid gel, and sample 3 becomes too hard. Therefore, the appropriate amount of potassium borate is 0.1 to 30%. Example 2 (Samples 4 to 6 in Table 1) Ion-exchanged water was added to PVA, potassium borate, sodium chloride (hereinafter referred to as NaCl), and paraben, and the mixture was heated and dissolved. As shown in Samples 4 to 6 in Table 1, electrolyte pastes were prepared with samples containing different weight percentages of NaCl. Good results were obtained for sample 5. In this case, the conductivity to the skin is better than that of Sample 2 of Example 1. Sample 4 has the same effect as sample 2 above, but NaCl
There is no observed conductivity effect on the skin due to the addition of . Regarding sample 6, a syneresis phenomenon occurred. Therefore, the appropriate amount of sodium chloride is 0.1 to 10%. Example 3 (Samples 7 to 9 in Table 1) Potassium chloride (hereinafter referred to as KCl) was used in place of NaCl in Example 2 above. Regarding Sample 8, the same conductive effect on the skin as in Sample 5 was obtained. Regarding Sample 7, the same effect as Sample 2 of Example 1 is obtained, but no effect due to the addition of KCl is observed. Regarding Sample 9, a syneresis phenomenon occurred. Therefore, 0.1 to 10% of KCl is appropriate. Example 4 (Samples 10 to 12 in Table 1) Ion-exchanged water was added to PVA, potassium borate, propylene glycol (PG), and paraben, and the mixture was heated and dissolved. As shown in samples 10 to 12 in Table 1,
Electrolyte pastes were made with samples containing different weight percentages of propylene glycol. Good results were obtained for sample 11. Sample 11 has better plasticity than Sample 2 of Example 1 and blends well with the skin. Sample 10 has the same effect as sample 2 above, but
No effect was observed by adding propylene glycol. Sample 12 becomes liquid and cannot be used as an electrolyte paste. Therefore, the appropriate amount of propylene glycol is 0.1 to 30%. Example 5 (Samples 13 to 15 in Table 1) Glycerin was used in place of propylene glycol in Example 4 above. Regarding Sample 14, the same effect as that of Sample 11 was obtained. Regarding Sample 13, the same effect as Sample 2 of Example 1 is obtained, but no effect due to the addition of glycerin is observed. Sample 15 becomes liquid and cannot be used as an electrolyte paste. Therefore, 0.1 to 20% of glycerin is appropriate. Example 6 (Samples 16 to 20 in Table 1) PVA, potassium borate, propylene glycol or glycerin, NaCl or KCl,
Ion-exchanged water was added to paraben and dissolved by heating.
As shown in Samples 16 to 20 in Table 1, electrolyte pastes were prepared using samples containing different weight percentages of each of the above components. Good results were obtained for samples 17, 18, and 19. These have better conductivity and plasticity to the skin than Sample 2 of Example 1. Sample 16 does not become a solid gel. Sample 20 is too hard to be suitable as an electrolyte paste. Table 2 shows the component percentages of the samples that gave good results in each of the above examples and their effects. In Table 2, the component percentage of PVA is not listed because it varies depending on the degree of polymerization, degree of saponification, and amount of residual acetic acid groups. However, the degree of polymerization is 500 to 2400, and the degree of saponification is 86.5.
PVA with a content of ~99 mol/% and a residual acetate group content of 3% or less is suitable. As shown in Table 2, a smaller amount of glycerin tends to increase plasticity than propylene glycol. Furthermore, although KCl and NaCl were used in Examples 2 and 3, other salts such as CaCl ₂ may also be used. Further, although propylene glycol and glycerin were used in Examples 4 and 5, other polyhydric alcohols may be used. Figures 1 and 2 show impedance changes of electrolyte pastes with different salt concentrations. In addition to the salts shown in the figures, the electrolyte pastes shown in these figures also contain 5% PVA, 1% potassium borate,
3% glycerin, 0.1% paraben and water (remainder)
It consists of FIG. 1 shows temporal changes in impedance to the skin obtained when two electrode elements are attached to a living body with an electrolyte paste interposed between them, and currents of different frequencies are passed through the electrode elements. KCl0.6%,
The cases of 10Hz and 100Hz are shown for each concentration of 2.0%. In either case, changes in impedance after approximately 30 minutes are reduced. Figure 2 shows how the impedance changes with frequency when two electrodes are bonded together with an electrolyte paste interposed and a current is passed through the electrodes, using electrolyte pastes with different salt concentrations. be. As shown in this figure,
A smaller amount of KCl can lower impedance than NaCl. In addition, in both figures 1 and 2, the diameter is 16
mm electrode elements are used.

【table】

【table】

[Table] [Effects of the Invention] According to the present invention, the electrolyte paste is not extruded during use, does not become sticky, and does not run away with sweat. Therefore, when electrodes are fixed with adhesive tape, the adhesive strength of the adhesive tape is not reduced, so the electrodes do not fall off even during long-term use. Moreover, it does not cause discomfort to the test subject. Furthermore, after use, the electrolyte paste of the present invention can be easily removed.

[Brief explanation of drawings]

Figure 1 shows the temporal change in impedance to the skin of the electrolyte pastes of the present invention with different KCl concentrations, and Figure 2 shows the changes in the frequency of the current applied to the electrolyte pastes of the present invention with different salt concentrations. FIG.

Claims (1)

[Claims] 1. An electrolyte paste for deriving biopotential made by crosslinking polyvinyl alcohol with boric acid ions. 2 Claim 1 comprising the addition of polyhydric alcohols
The described electrolyte paste for deriving biopotential. 3. The electrolyte paste for deriving biopotential according to claim 1 or 2, wherein a salt is added.