阅读说明：本技术 干电极粘合剂 (Dry electrode binder ) 是由 C·内格勒 I·范德默伦 S·吉利森 T·罗舍克 F·格特尔 A·贝斯莱尔 A·施奈德 于 2020-03-02 设计创作，主要内容包括：本发明涉及电极粘合剂,这是一种离子传导性的基于(甲基)丙烯酸酯的压敏粘合剂,允许长时间生物信号监测而不刺激皮肤及损失信号质量。(The present invention relates to an electrode adhesive which is an ionically conductive (meth) acrylate-based pressure sensitive adhesive allowing for long-term bio-signal monitoring without skin irritation and loss of signal quality.)

1. An ion-conductive pressure-sensitive adhesive composition comprising

a) A (meth) acrylate resin comprising at least 10% of (meth) acrylate monomers comprising OH-groups, based on the total weight of the (meth) acrylate resin; and

b) an ionic liquid.

2. The ionically conductive pressure sensitive adhesive composition of claim 1, wherein the ionic liquid is selected from the group consisting of: imidazolium acetate, imidazolium sulfonate, imidazolium chloride, imidazolium sulfate, imidazolium phosphate, imidazolium thiocyanate, imidazolium dicyanamide, imidazolium benzoate, imidazolium trifluoromethanesulfonate, choline trifluoromethanesulfonate, saccharin choline, sulfamate, pyridinium acetate, pyridinium sulfonate, pyridinium chloride, pyridinium sulfate, pyridinium phosphate, pyridinium thiocyanate, pyridinium dicyanamide, pyridinium benzoate, pyridinium trifluoromethanesulfonate, pyrrolidinium acetate, pyrrolidinium sulfonate, pyrrolidinium chloride, pyrrolidinium sulfate, pyrrolidinium phosphate, pyrrolidinium thiocyanate, pyrrolidinium dicyanamide, pyrrolidinium benzoate, pyrrolidinium trifluoromethanesulfonate, phosphonium acetate, phosphonium sulfonate, phosphonium chloride, phosphonium sulfate, pyrrolidinium thiocyanate, Dicyandiamide phosphonium, benzoic acid phosphonium, trifluoromethanesulfonic acid phosphonium, acetic acid sulfonium, sulfonic acid sulfonium, chloride sulfonium, sulfuric acid sulfonium, phosphoric acid sulfonium, thiocyanic acid sulfonium, dicyandiamide sulfonium, benzoic acid sulfonium, trifluoromethanesulfonic acid sulfonium, ammonium acetate, ammonium sulfonate, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium thiocyanate, dicyandiamide ammonium, ammonium benzoate, ammonium triflate and mixtures thereof.

3. The ionically-conductive pressure sensitive adhesive composition according to claim 1 or 2, wherein the (meth) acrylate monomer comprising OH "groups is present in the (meth) acrylate resin in an amount of at least 15 wt. -%, preferably at least 20%, more preferably at least 25%, and most preferably at least 30%, but not more than 65%, preferably not more than 60%, more preferably not more than 55%, and most preferably not more than 50% of the total weight of the (meth) acrylate resin.

4. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 3, wherein the (meth) acrylate resin is formed from monomers selected from the group consisting of: hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, butyl acrylate, ethylhexyl acrylate, acrylic acid, C1-C18 alkyl (meth) acrylates, (meth) acrylamides, vinyl acetate, N-vinyl caprolactam, acrylonitrile, vinyl ether, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate and mixtures thereof, preferably formed from monomers selected from the group consisting of: hydroxyethyl acrylate, methyl methacrylate, butyl acrylate, ethylhexyl acrylate and mixtures thereof, and more preferably, the (meth) acrylate resin is formed from hydroxyethyl acrylate, methyl (meth) acrylate, butyl acrylate and ethylhexyl acrylate.

5. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 4, wherein the (meth) acrylate resin is present at 5-80 wt. -%, preferably 15-75 wt. -%, and more preferably 30-70 wt. -%, based on the total weight of the composition.

6. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 5, wherein the ionic liquid is selected from the group consisting of: 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium sulfate ethyl ester salt, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium dicyanamide salt, 1-ethyl-3-methylimidazolium benzoate, choline trifluoromethanesulfonate, saccharin choline, acetylcholine sulfamate, N-cyclohexylsulfamate, tris (2-hydroxyethyl) methylammonium methylsulfate, ammonium methyl sulfate, ammonium chloride, sodium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-allyl-3-ethylimidazolium bis (trifluoromethanesulfonyl) imide salt, choline acetate and mixtures thereof, and is more preferably selected from: 1-ethyl-3-methylimidazolium benzoate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, choline trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium acetate, choline acetate, diethyl 1-ethyl-3-methylimidazolium phosphate, 1-allyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, ethyl 1-ethyl-3-methylimidazolium sulfate, 1-ethyl-3-methylimidazolium thiocyanate, sodium hydrogen sulfide, sodium chloride, 1-ethyl-3-methylimidazolium dicyanamide salt, choline saccharinate, choline acetaminosulfonate and mixtures thereof.

7. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 6, wherein the ionic liquid is present at 0.1 to 35 wt. -%, preferably 0.5 to 25 wt. -%, and more preferably 1 to 15 wt. -%, based on the total weight of the composition.

8. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 7, further comprising an ionic conductivity promoter, preferably selected from the group consisting of choline chloride, choline bitartrate, choline dihydrogen citrate, choline phosphate, choline gluconate, choline fumarate, choline carbonate, choline pyrophosphate, and mixtures thereof.

9. The ionically conductive pressure sensitive adhesive composition according to claim 8, wherein the ionic conductivity promoter is present at 0.1 to 35 wt.%, preferably 0.5 to 25 wt.%, and more preferably 1 to 15 wt.%, based on the total weight of the composition.

10. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 9, further comprising electrically conductive particles, preferably selected from: metal particles and metal nanoparticles, metal-containing particles and nanoparticles, graphite particles and nanoparticles, carbon nanowires, conductive polymer particles and nanoparticles, and mixtures thereof, more preferably selected from the group consisting of: silver-containing particles, silver particles, copper-containing particles, silver nanowires, copper nanowires, graphite particles, carbon particles, and mixtures thereof, and even more preferably selected from graphite particles, carbon particles, and mixtures thereof.

11. The ion-conductive pressure sensitive adhesive composition according to any one of claims 1 to 10, further comprising a polyether polyol, preferably selected from polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and more preferably polyethylene glycol having a weight average molecular weight of 300-1000g/mol, more preferably 350-750g/mol and even more preferably 380-420g/mol, wherein the molecular weight is measured by gel permeation chromatography according to DIN 55672-1:2007-08 with THF as eluent.

12. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 11, further comprising a solvent selected from the group consisting of: water, ethyl acetate, butyl diglycol, 2-butoxyethanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methanol, isopropanol, butanol, dibasic esters, hexane, heptane, 2, 4-pentanedione, toluene, xylene, benzene, hexane, heptane, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether and mixtures thereof, preferably, the solvent is selected from the group consisting of: ethyl acetate, butyl acetate, ethylene glycol, propylene glycol, and mixtures thereof.

13. The ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 12, wherein the adhesive has an impedance value of less than 1,000,000Ohm at 1000Hz, preferably less than 100,000Ohm at 1000Hz, and more preferably less than 40,000Ohm at 1000Hz, wherein the impedance is established by connecting two pressure sensitive adhesives each coated with 25 μ ι η ionically conductive adhesive and coated with the adhesive, and wherein the impedance is determined by the adhesive's physical propertiesThe contact area is 0.25cm²To measure.

14. A dry film formed from the ionically conductive pressure sensitive adhesive composition of any one of claims 1-13.

15. Use of the ionically conductive pressure sensitive adhesive composition according to any one of claims 1 to 13 or the dry film according to claim 14 as a contact medium in dermal applications, as part of an electrode for measuring bio-signals from the skin.

Technical Field

The present invention relates to an electrode adhesive, which is an ionically conductive pressure sensitive adhesive, allowing for long-term bio-signal monitoring without skin irritation and loss of signal quality.

Background

Various types of electrodes are used to measure biological signals, such as Electrocardiogram (ECG), electroencephalogram (EEG), and Electromyogram (EMG).

For example, the ECG electrodes currently used are connected to the skin via a gel that acts as an electrolyte and transmits body signals to the electrodes. However, they dry out over time and cannot be used for long-term measurements. In most cases, it is not recommended to use it for more than 24 hours. In addition, they do not have a long storage time, in most cases up to one month after opening, and furthermore, they require special packaging to prevent them from drying out.

In particular, currently used gel electrodes have a high salt concentration, which is required for low impedance and good signal quality, while at the same time it causes skin irritation for many patients. Furthermore, these electrodes contain relatively high amounts of water. High water content is one reason these electrodes tend to dry out and therefore cannot be used for long-term measurements (up to three days), since the signal quality decreases with decreasing water content. Current gel electrodes are attached to the skin with a ring of pressure sensitive skin adhesive surrounding the inner gel.

Currently, there are also tab electrodes (tab electrodes) on the market, which are attached to the skin via gel-type adhesives. These electrodes do not require additional skin adhesive as the gel adheres itself to the skin. However, these electrodes also contain salt and water, and can dry out over time and are therefore not suitable for long-term measurements. The cohesion of the binder in these electrodes is generally poor, leading to cohesive failure upon removal of the electrode.

Alternatively, a pressure sensitive adhesive containing a conductive filler, such as carbon black, may be used in the electrode to measure the bio-signal. A disadvantage of such electrodes is that high carbon black concentrations are required, which leads to a loss of adhesion. Furthermore, the signal quality in such electrodes is poor without an ion-conducting binder.

In another electrode solution, the electrode contains a binder comprising a combination of carbon black and a salt. Electrophoretic alignment of the conductive filler is required in order to obtain sufficient impedance in this solution. However, this electrophoretic activation step makes the electrode production expensive and complicated.

Therefore, there is a need for an electrode for measuring bio-signals that can be used for one week without losing signal or adhesion, while not drying out or sensitizing or irritating the skin.

Disclosure of Invention

The present invention relates to an ion-conductive pressure sensitive adhesive composition comprising a) a (meth) acrylate resin comprising at least 10% by total weight of the (meth) acrylate resin of (meth) acrylate monomers comprising OH-groups (hydroxyl groups); and b) an ionic liquid.

The present invention also relates to a dry film formed from the ionically conductive pressure sensitive adhesive composition according to the present invention.

The invention encompasses the use of the ionically conductive pressure sensitive adhesive composition or dry film according to the invention as a contact medium in dermal applications, as part of an electrode for measuring biological signals from the skin.

Drawings

FIG. 1 shows impedance spectra of pressure sensitive adhesives containing different functional groups with or without 1-ethyl-3-methylimidazolium benzoate (1-ethyl-3-methylimidazolium benzoate) as the ionic liquid.

Fig. 2 shows the impedance spectrum of a pressure-sensitive adhesive containing various ionic liquids according to the invention.

Fig. 3a shows a silver electrode coated with an ion-conducting pressure-sensitive adhesive according to the invention containing additional carbon black particles.

Figure 3b shows an ECG spectrum recorded with a silver electrode attached to the skin via an ion-conductive pressure sensitive adhesive containing 1-ethyl-3-methylimidazolium acetate.

FIG. 4 shows an impedance spectrum of a pressure sensitive adhesive according to the present invention containing variable amounts of PEG and 1-ethyl-3-methylimidazolium ethyl sulfate.

FIG. 5 shows the impedance spectrum of a pressure-sensitive adhesive according to the invention with a modified carbon black and choline acetate.

FIG. 6 shows impedance spectra of compositions according to example 23 (solid line) and example 5 (dotted line) on Ag/AgCl electrodes.

Fig. 7 shows defibrillation overload recovery test curves of examples 4,5, and 13.

Fig. 8 shows defibrillation overload recovery discharge curves according to ANSI/AAMI EC12:2000/(R)2015 for electrode pairs having electrode adhesives according to example 5.

Fig. 9 shows defibrillation overload recovery discharge curves according to ANSI/AAMI EC12:2000/(R)2015 for electrode pairs having electrode adhesives according to example 23.

Fig. 10 shows the voltage increase during current biasing for electrode samples with different binder compositions (examples 5 and 23).

Fig. 11 shows the voltage increase during long-term current biasing (200nA) for the electrode sample with electrode binder (example 23).

Fig. 12 shows the voltage increase during long-term current bias (2 μ Α) for the electrode samples with electrode binder (example 23).

Figure 13 shows the offset instability and internal noise measurements for electrode samples with electrode binders according to the present invention (example 23).

Fig. 14 shows impedance spectra of counter electrodes containing dry electrode binders with varying degrees of OH functionality.

Detailed Description

The invention is described in more detail in the following paragraphs. Aspects so described may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

In the context of the present invention, unless the context dictates otherwise, the terms used are to be construed in accordance with the following definitions.

As used herein, the singular forms "a" and "an" include singular and plural referents unless the context clearly dictates otherwise.

As used herein, the terms "comprising," and "comprising" are synonymous with "including" or "containing" and are inclusive or open-ended and do not exclude additional unrecited elements, or method steps.

The recitation of numerical endpoints includes all numbers and fractions subsumed within each range and the recited endpoint.

All percentages, parts, ratios, etc. mentioned herein are by weight unless otherwise indicated.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as an upper preferable value and a lower preferable value, it is understood that any range obtained by combining any upper limit or preferred value with any lower limit or preferred value is specifically disclosed without regard to whether or not the obtained range is explicitly mentioned in the context.

All references cited in this specification are incorporated herein by reference in their entirety.

Unless defined otherwise, all terms, including technical and scientific terms, used in disclosing the invention, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention.

The dry electrode adhesive according to the invention is an ion-conducting Pressure Sensitive Adhesive (PSA) with low resistance and good skin compatibility.

The ion-conductive pressure-sensitive adhesive according to the present invention is based on a polar solvent-based acrylic pressure-sensitive adhesive having high gas permeability and a non-toxic, non-irritating ionic liquid that produces ionic conductivity.

The ionically conductive pressure sensitive adhesive composition according to the present invention can be used as a dry film, which provides a technical solution for long term monitoring of bio-signals by acting as a functional contact between the electrode and the skin. It does not dry out and it does not cause skin irritation, compared to the gel type electrode currently on the market. Furthermore, the impedance of the PSA according to the invention is extremely low without any addition of water.

The present invention relates to an ion-conductive pressure-sensitive adhesive composition comprising a (meth) acrylate resin containing a (meth) acrylate monomer containing an OH-group (hydroxyl group) and an ionic liquid.

The ion-conductive pressure sensitive adhesive composition according to the present invention comprises a (meth) acrylate resin comprising at least 10% of (meth) acrylate monomers comprising OH-groups, based on the total weight of the (meth) acrylate resin.

Suitable (meth) acrylate resins for use in the present invention are preferably formed from monomers selected from the group consisting of: hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, butyl acrylate, ethylhexyl acrylate, acrylic acid, C1-C18 alkyl (meth) acrylates, (meth) acrylamides, vinyl acetate, N-vinyl caprolactam, acrylonitrile, vinyl ether, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate and mixtures thereof, preferably formed from monomers selected from the group consisting of: hydroxyethyl acrylate, methyl methacrylate, butyl acrylate, ethylhexyl acrylate and mixtures thereof, and more preferably, the (meth) acrylate resin is formed from hydroxyethyl acrylate, methyl (meth) acrylate, butyl acrylate and ethylhexyl acrylate.

Suitable commercially available (meth) acrylate resins for use in the present invention include, but are not limited to, Loctite DURO-TAK 222A, Loctite DURO-TAK 87-202A, available from Henkel; loctite DURO-TAK 87-402A; loctite DURO-TAK 73-626A.

Applicants have found that PSAs comprising (meth) acrylate resins containing at least 10% of (meth) acrylate monomers comprising OH-groups provide good impedance and the electrodes do not dry out, and that they can be used for longer period measurements (higher OH content increases the water vapor transmission rate of the polymer, which helps to increase breathability and prolong wear time).

Preferably, the (meth) acrylate monomer comprising OH-groups is present in the (meth) acrylate resin in an amount of at least 15 wt%, more preferably at least 20%, more preferably at least 25%, and most preferably at least 30%, but not more than 65%, preferably not more than 60%, more preferably not more than 55%, and most preferably not more than 50% of the total weight of the (meth) acrylate resin.

When the (meth) acrylate monomer including OH-groups in the (meth) acrylate resin is more than 65% by weight of the total weight of the (meth) acrylate resin, a higher OH-group content may adversely affect the adhesive characteristics.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may comprise 5 to 80% by weight, preferably 15 to 75%, and more preferably 30 to 70% by weight of the total weight of the composition of the (meth) acrylate resin.

Lower amounts of (meth) acrylate resin may result in poor adhesive properties and be detrimental to film forming properties, while too high an amount may result in poor conductivity.

The ionically conductive pressure sensitive adhesive composition according to the present invention comprises an ionic liquid, preferably a non-toxic, non-irritating ionic liquid that produces ionic conductivity.

More specifically, the ionically conductive pressure sensitive adhesive composition according to the present invention comprises an ionic liquid selected from the group consisting of: imidazolium acetate, imidazolium sulfonate, imidazolium chloride, imidazolium sulfate, imidazolium phosphate, imidazolium thiocyanate, imidazolium dicyanamide, imidazolium benzoate, imidazolium trifluoromethanesulfonate, choline trifluoromethanesulfonate (choline triflate), saccharin choline, choline sulfamate (choline sulfamate), pyridinium acetate, pyridinium sulfonate, pyridinium chloride, pyridinium sulfate, pyridinium phosphate, pyridinium thiocyanate, pyridinium dicyanamide, pyridinium benzoate, pyridinium trifluoromethanesulfonate, pyrrolidinium acetate, pyrrolidinium sulfonate, pyrrolidinium chloride, pyrrolidinium sulfate, pyrrolidinium phosphate, pyrrolidinium thiocyanate, pyrrolidinium dicyanamide, pyrrolidinium benzoate, pyrrolidinium trifluoromethanesulfonate, phosphonium acetate, sulfonic acid, phosphonium chloride, phosphonium sulfate, Phosphonium phosphate, phosphonium thiocyanate, phosphonium dicyanamide, phosphonium benzoate, phosphonium triflate, sulfonium acetate, sulfonium sulfonate, sulfonium chloride, sulfonium sulfate, sulfonium phosphate, sulfonium thiocyanate, sulfonium dicyanamide, sulfonium benzoate, sulfonium triflate, ammonium acetate, ammonium sulfonate, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium thiocyanate, ammonium dicyanamide, ammonium benzoate, ammonium triflate, and mixtures thereof.

Preferably, the ionic liquid is selected from: 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium sulfate ethyl ester salt, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium dicyanamide salt, 1-ethyl-3-methylimidazolium benzoate, choline trifluoromethanesulfonate, saccharin choline, acetylcholine sulfamate, N-cyclohexylsulfamate, tris (2-hydroxyethyl) methylammonium methylsulfate, ammonium methyl sulfate, ammonium chloride, sodium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-allyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, choline acetate, and mixtures thereof.

More preferably, the ionic liquid is selected from: 1-ethyl-3-methylimidazolium benzoate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, choline trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium acetate, choline acetate, diethyl 1-ethyl-3-methylimidazolium phosphate, 1-allyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, ethyl 1-ethyl-3-methylimidazolium sulfate, 1-ethyl-3-methylimidazolium thiocyanate, sodium hydrogen sulfide, sodium chloride, 1-ethyl-3-methylimidazolium dicyanamide salt, choline saccharinate, choline acetaminosulfonate and mixtures thereof.

The ionic liquids mentioned above are preferred because of their good solubility and low toxicity for the (meth) acrylate resins according to the invention.

In one embodiment, two or more ionic liquids are used, in this embodiment, the ionic liquids are selected from: 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium sulfate ethyl ester salt, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium dicyanamide salt, 1-ethyl-3-methylimidazolium benzoate, choline trifluoromethanesulfonate, saccharin choline, acetylcholine sulfamate, N-cyclohexylsulfamate, tris (2-hydroxyethyl) methylammonium methylsulfate, ammonium methyl sulfate, ammonium chloride, sodium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-allyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt, choline acetate;

preferably, the two or more ionic liquids are selected from: 1-ethyl-3-methylimidazolium benzoate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, choline trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium acetate, choline acetate, diethyl 1-ethyl-3-methylimidazolium phosphate, 1-allyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, ethyl 1-ethyl-3-methylimidazolium sulfate, 1-ethyl-3-methylimidazolium thiocyanate, sodium hydrogen sulfide, sodium chloride, 1-ethyl-3-methylimidazolium dicyanamide salt, choline saccharin, choline acetamino sulfonate.

Suitable commercially available ionic liquids for use in the present invention include, but are not limited to, basitics ST80, basitics Kat1, basitics BC01, basitics VS11, basitics VS03, and Efka IO 6785, all of which are available from BASF.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may comprise 0.1 to 35 wt%, preferably 0.5 to 25 wt%, and more preferably 1 to 15 wt% of the ionic liquid, based on the total weight of the composition.

If the amount of ionic liquid is too low, the adhesive may not exhibit any ionic conductivity and the signal may be lost, while too high an amount may not provide signal quality improvement, but may increase skin irritation potential and decrease adhesive properties.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may further comprise an ionic conductivity promoter, preferably a non-toxic, non-irritating ionic conductivity promoter that produces additional ionic conductivity.

The ionic conductivity promoter is semi-solid or solid at room temperature and is soluble in the ionic liquid. Which has good compatibility with the (meth) acrylate resin according to the present invention.

The ionic conductivity enhancer suitable for use in the present invention is selected from the group consisting of choline chloride, choline bitartrate, choline dihydrogen citrate, choline phosphate, choline gluconate, choline fumarate, choline carbonate, choline pyrophosphate, sodium chloride, lithium chloride, potassium chloride, calcium chloride, magnesium chloride, aluminum chloride, silver chloride, ammonium chloride, alkylammonium chloride, dialkylammonium chloride, trialkylammonium chloride, tetraalkylammonium chloride, and mixtures thereof.

According to the present invention, the ion-conductive pressure-sensitive adhesive composition according to the present invention may comprise 0.1 to 35 wt%, preferably 0.5 to 25 wt%, and more preferably 1 to 15 wt%, of the ionic conductivity promoter, based on the total weight of the composition.

If the amount of the ionic conductivity promoter is too low, the pressure-sensitive adhesive may not exhibit any ionic conductivity and the signal may be lost, while too high an amount may not provide signal quality improvement, but may increase skin irritation potential and decrease adhesive characteristics.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may further comprise conductive particles.

Preferably, the conductive particles are selected from: metal particles and metal nanoparticles, metal-containing particles and nanoparticles, graphite particles and nanoparticles, carbon nanowires, conductive polymer particles and nanoparticles, and mixtures thereof, more preferably selected from the group consisting of: silver-containing particles, silver particles, copper-containing particles, silver nanowires, copper nanowires, graphite particles, carbon particles, and mixtures thereof, and even more preferably selected from graphite particles, carbon particles, and mixtures thereof.

Graphite particles and carbon particles are preferred because they do not cause skin irritation, but provide sufficient conductivity.

Suitable commercially available conductive particles for use in the present invention include, but are not limited to, Ensaco 250G, Timrex KS6, available from Timcal; printex XE2B, available from necrbo; C-Nergy Super C65 from Imerys and Vulcan XC72R from Cabot.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may comprise 0.1 to 35 wt%, preferably 0.5 to 25 wt%, and more preferably 1 to 15 wt% of the conductive particles, based on the total weight of the composition.

If the amount of the conductive particles is too low, it may result in poor conductivity, while an excessively high amount may result in loss of adhesive properties.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may further comprise a polyether polyol. Preferably, the polyether polyol is selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG) and mixtures thereof.

The applicant has found that the addition of polyether polyols is an exceptionally good host of ionic conductivity due to the open and flexible molecular chains, and thus has a positive effect on the impedance. Applicants have found that small amounts of polyether polyols have a positive effect, which is beneficial for the skin compatibility of the composition.

Preferably, the weight average molecular weight (Mw) of the polyether polyol may be 300-1000g/mol, preferably 350-750g/mol and more preferably 380-420g/mol, as measured by gel permeation chromatography according to DIN 55672-1:2007-08 with THF as eluent.

Suitable commercially available polyether polyols for use in the present invention include, but are not limited to, Kollisolv PEG400 available from BASF.

The ionically conductive pressure sensitive adhesive composition according to the present invention may comprise from 0.1 to 35 wt%, preferably from 0.5 to 25 wt%, and more preferably from 1 to 15 wt%, of a polyether polyol, based on the total weight of the composition.

Too high a polyether polyol amount may result in a loss of adhesive properties.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may further comprise a solvent.

Suitable solvents for use in the present invention may be selected from: water, ethyl acetate, butyl diglycol, 2-butoxyethanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, methanol, isopropanol, butanol, dibasic esters, hexane, heptane, 2, 4-pentanedione, toluene, xylene, benzene, hexane, heptane, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether and mixtures thereof, preferably, the solvent is selected from the group consisting of: ethyl acetate, butyl acetate, ethylene glycol, propylene glycol, and mixtures thereof.

Suitable commercially available solvents for use in the present invention include, but are not limited to, ethyl acetate and ethylene glycol available from Brenntag, butyl acetate available from Shell Chemicals, and propylene glycol available from Lyondell.

The ion-conductive pressure-sensitive adhesive composition according to the present invention may comprise 10 to 90 wt%, preferably 20 to 80 wt%, and more preferably 30 to 70 wt% of a solvent, based on the total weight of the composition.

If the amount of solvent is too low, this may lead to processability problems, since the viscosity is too high and the (meth) acrylate resin may not be completely soluble. Too high an amount may result in loss of functionality and the viscosity of the adhesive is too low to handle.

The ion-conductive pressure-sensitive adhesive composition according to the present invention preferably has a resistance value of less than 1,000,000Ohm at 1000Hz, preferably less than 100,000Ohm at 1000Hz, and more preferably less than 40,000Ohm at 1000Hz, wherein the resistance is obtained by connecting two electrodes each coated with 25 μm ion-conductive pressure-sensitive adhesive (contact area is0.25cm²) To measure.

In the composition according to the invention, the combination of the (meth) acrylate resin and the ionic liquid results in a low impedance. The ionic liquid provides ionic conductivity, however, if the ionic liquid is not miscible with the (meth) acrylate resin, no ionic conductivity will be seen in the pressure sensitive adhesive. In embodiments where PEG is added to the composition, the additional ether groups from the PEG make the system more polar and enhance the ionic conductivity of the ionic liquid in the (meth) acrylate resin.

The ion-conductive pressure-sensitive adhesive composition according to the present invention has high air permeability. Good breathability is obtained if water can easily penetrate the adhesive layer. To obtain this effect, very polar resins are required, in which case the OH-functional groups support and improve the gas permeability.

The adhesive according to the invention had a viscosity of about 4600g/m in 24 hours²The permeability value of (a). By way of comparison, a standard acrylic PSA has a weight average molecular weight of about 2000g/m in 24 hours²The permeability value of (a). Breathability is measured via Moisture Vapor Transmission Rate (MVTR) measurement according to ASTM D1653.

The present invention also relates to a dry film formed from the ionically conductive pressure sensitive adhesive composition according to the present invention.

Dry film formation can be performed as follows: the solvent is removed by coating the ion-conductive pressure-sensitive adhesive composition onto a support substrate, such as a membrane, and drying the membrane in an oven, for example, at 120 ℃ for 3 minutes, and a dry film of the ion-conductive pressure-sensitive adhesive is formed on the support substrate.

Known methods for preparing pressure sensitive adhesives can be used. Specifically, examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating and air knife coating methods, dip and curtain coating methods, and extrusion coating methods by die coaters (die coaters). The invention also relates to the use of the ion-conducting pressure-sensitive adhesive composition according to the invention in dermal applications as a contact medium, as part of an electrode for measuring bio-signals from the skin.

The invention also covers the use of the dry film according to the invention as a contact medium in skin applications, as part of an electrode for measuring bio-signals from the skin.

Impedance is a key parameter of electrode function. The requirements and measurement procedures for disposable ECG electrodes are defined by ANSI/AAMI EC12:2000/(R) 2015. For two electrodes connected to each other by an adhesive side agent, the impedance of the electrodes at 10Hz needs to be below 2000Ohm on average.

The electrode comprising the ionically conductive pressure sensitive adhesive according to the present invention has an impedance value of less than 100,000Ohm at 10Hz, preferably less than 10,000Ohm at 10Hz, and more preferably less than 2,000Ohm at 10Hz, wherein the impedance is measured by connecting the two electrodes to each other via their adhesive sides.

Another important test for ECG electrodes is Defibrillation Overload Recovery (DOR) (measured according to ANSI/AAMI EC12:2000/(R) 2015). In this context, defibrillation overload recovery refers to the voltage drop across the electrodes when a 10 μ F capacitor (charged to 200V) is discharged via the sample (which consists of two electrodes connected to each other via the adhesive side; the electrodes here correspond to the adhesive on the Ag/AgCl conductive layer on the non-conductive substrate). For a successful test, this must be satisfied 3 consecutive times. The allowable voltage range is shown in table 1 below, and is the maximum allowable voltage at a time, or the maximum allowable voltage difference at a certain time interval:

TABLE 1

Defibrillation overload recovery may be affected by the choice of ionic liquid/salt, especially the anion of the ionic liquid/salt. Chloride provides a rapid defibrillation overload recovery time on the Ag/AgCl electrode. In principle, every chloride can be used, however, chlorides of ionic liquids (e.g. EMIM chloride or choline chloride) are preferred due to their good compatibility with the binder material. However, EMIM chloride in the adhesive composition may not produce bulk conductivity sufficient to meet impedance requirements. Surprisingly, ionic liquids having anions that provide good bulk conductivity (e.g., EMIM dicyanamide salts) do not exhibit rapid defibrillation overload recovery. Therefore, for ideal electrode behavior, a good balance between good bulk conductivity and fast discharge characteristics needs to be found. The combination of two or more different ionic liquids or salts in an ionically conductive PSA according to the present invention may be a solution to meet all performance requirements of the electrode.

It has been found that chloride salts already provide fast discharge characteristics at lower amounts (< 2 wt% of dry adhesive films according to the invention) because electrodes with a chloride containing adhesive have a DC resistance in the kOhm range, whereas electrodes with a chloride free adhesive have a DC resistance of about 10 MOhm. Only low DC resistivity allows the sample to discharge in a short time and, therefore, may comply with defibrillation overload recovery requirements.

In the composition according to the invention, the combination of the (meth) acrylate resin and the ionic liquid allows for a rapid discharge of the electrode sample and meets defibrillation overload requirements for electrodes having a matching interface between the adhesive and the conductive layer.

Examples

Materials:

LOCTITE DURO-TAK 222A, LOCTITE DURO-TAK 1053 and LOCTITE DURO-TAK 387-2518 from Henkel AG & Co. KGaA

LOCTITE EDAG 6038E SS from Henkel AG & Co

1-Ethyl-3-methylimidazolium benzoate from BASF

1-Ethyl-3-methylimidazolium triflate from Proionic

1-Ethyl-3-methylimidazolium dicyanamide salt from BASF

1-Ethyl-3-methylimidazolium chloride from BASF

1-Ethyl-3-methylimidazolium tetrafluoroborate from Sigma-Aldrich

1-Ethyl-3-methylimidazolium methanesulfonate from Proionic

1-Ethyl-3-methylimidazolium diethyl phosphate salt from IoLiTec

AMIM bis (trifluoromethanesulfonyl) imide salt from Sigma-Aldrich

1-Ethyl-3-methylimidazolium ethyl sulfate salt from BASF

1-Ethyl-3-methylimidazolium thiocyanate from BASF

PEG400 from Fluka

Choline chloride from Sigma-Aldrich

Choline hydroxide solution from Sigma-Aldrich

Sodium saccharin hydrate from Sigma-Aldrich

Trifluoromethanesulfonic acid, Sigma-Aldrich

Acesulfam K from Sigma-Aldrich

C-Nergy Super C65 from Imerys

Hydrogenated tallow alkyl (2-ethylhexyl) dimethyl ammonium methyl sulfate available from Akzo Nobel (Arquad HTL8-MS)

Choline trifluoromethanesulfonate was prepared according to chem.commun.,2011,47, 6401-.

Choline saccharinate and choline acetaminosulfonate were prepared according to J.Phys.chem.B2007,111,19, 5254-5263.

Example 1 and comparative examples 1 to 5

Impedance of ionic liquids in pressure sensitive adhesives with different functionalities

Example 1

2g of Loctite Duro-TAK 222A (solids content: 41%) and 0.091g of 1-ethyl-3-methylimidazolium benzoate are mixed in a conditioning mixer for 3 minutes at 2000 rpm.

Comparative example 3

2g of Loctite Duro-TAK 1053 (solids content: 48%) and 0.108g of 1-ethyl-3-methylimidazolium benzoate are mixed in a conditioning mixer for 3 minutes at 2000 rpm.

Comparative example 5

2g of Loctite Duro-TAK 387-2516 (solids content: 42%) and 0.094g of 1-ethyl-3-methylimidazolium benzoate were mixed in a conditioning mixer at 2000rpm for 3 minutes.

The mixture was coated onto a release liner and dried at room temperature for 30 minutes, resulting in a PSA film with a thickness of 20 μm. Subsequently, the coated film (drawdown) was cured at 120 ℃ for 3 minutes and covered with another release liner. Table 2 lists the (meth) acrylate resin and ionic liquid used in the mixture, the OH-functionality of the (meth) acrylate resin (the amount of OH-functional (meth) acrylate monomer based on the total weight of the (meth) acrylate resin), and the amount of ionic liquid (wt% of the dry PSA film).

Table 2: 1-Ethyl-3-methylimidazolium benzoate (EMIM benzoate) PSA samples

For impedance measurements (fig. 1), the dry PSA film was transferred onto an aluminum (Al) foil. Two pieces of PSA-Al film were cut and glued together to form a film having 0.25cm²Area and 40 μm PSA thickness. Potentiostat from Metrohm Autolab at 9X 10⁵The impedance is measured in the frequency range to 0.1 Hz. Figure 1 shows that a high degree of OH functionalization results in lower impedance, especially in combination with ionic liquids.

Examples 2 to 15 and comparative example 6

Comparison of Ionic liquids in pressure sensitive adhesives with high OH functionality

5g of Loctite Duro-TAK 222A (solids content: 41%) and 0.228g of the respective ionic liquids were mixed in a conditioning mixer at 2000rpm for 3 minutes.

The mixture (table 3) was coated onto a release liner and dried at room temperature for 30 minutes, yielding a PSA film with a thickness of 20-30 μm. Subsequently, the coating film was cured at 120 ℃ for 3 minutes and covered with another release liner.

Table 3: DURO-TAK 222A with various ionic liquids

Impedance measurement:

for impedance measurements (fig. 2), the dry PSA film was transferred onto Al foil. Cutting machineTwo pieces of PSA-Al film were cut and glued together to form a film having a thickness of 0.25cm²Area and PSA thickness of 40-60 μm. Potentiostat from Metrohm Autolab at 9X 10⁵The impedance is measured in the frequency range to 0.1 Hz.

Fig. 2 illustrates that the addition of ionic liquid to OH-functionalized pressure sensitive adhesive significantly reduces the impedance. The plateau visible in the curve corresponds to the bulk resistance of the adhesive and is shifted to a lower value by the ionic liquid. The ionic liquids that had the greatest effect on the reduction of impedance were EMIM dicyanamide, EMIM thiocyanate and EMIM triflate.

Skin compatibility study:

the skin compatibility of the pressure-sensitive adhesive composition was measured in an in vitro skin irritation test using the OS-REp model (Open Source regulated adhesives). 25 μ L of the active pressure sensitive adhesive composition was applied to the epidermis model. After 42 hours of incubation and 3 hours of incubation with MTT (200. mu.l, 1mg/ml MTT (3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide)), formazan was performedThe optical density at 570-590nm was extracted and measured. The relative viability of the cells was calculated by optical density.

The skin irritation test was a modified version of the OS-REp test according to OECD TG 439, OECD TG 439 was a protocol to identify irritant pure substances and salts.

A typical contact time of the potential irritant with the skin model is 35 minutes. Subsequently, the substance to be tested was washed off and an incubation time of 42 hours was started. For relative viability of cells, > 50% of the material may be considered non-irritating.

Since a pressure sensitive adhesive that could not be washed off was tested, the contact time was significantly longer (42 hours instead of 35 minutes), indicating that the test conditions of the present invention are more severe. Table 4 illustrates the results, which show that conductive PSAs have excellent skin compatibility. Comparative example 6, which contained a quaternary ammonium salt instead of an ionic liquid, showed increased irritation potential compared to the binder according to the invention.

Table 4: summary of in vitro skin irritation results

	Viability (%, according to the epidermal test)
		Comparative example 1	86±4
Example 1	78±4
		Example 8	84±8
Example 11	63±8
		Example 12	95±18
Example 13	80±10
		Comparative example 6	20±8

Examples 7, 16 and 17

EGG signal detection

ECG measurements were made on a portable MedX5 ECG device, which can be used with all types of standard electrodes. ECG spectra were recorded over a period of 30 seconds and were viewable with software Heartscan 2.0 provided by MedX 5.

To prepare dry electrodes, silver electrodes were printed using commercial Henkel silver ink Loctite ECI 1010E & C and laminated with ion-conducting PSA according to the invention. Fig. 3a illustrates an electrode set for ECG measurement. The electrodes were laminated with a PSA filled for better visibility with an ionic liquid (adhesive according to the invention) and carbon black.

ECG spectra of PSA filled with different concentrations of EMIM acetate were recorded (table 5).

Table 5: sample for ECG signal monitoring

Fig. 3b illustrates the recorded ECG spectrum. ECG signals were recorded using three electrodes (working, counter and reference) placed at the inner side of the human forearm (two on the left arm and one on the right arm) and the lead between the left and right arms was measured (derivitization). Monitoring was performed while the arm was stationary (no movement) and continuously moving the arm up and down (movement). Good ECG signals were obtained in all cases, especially for higher ionic liquid concentrations.

Examples 18 to 19 and comparative example 7

Enhancement of ionic conductivity in PSA PEG400 blends

Comparative example 7

4.15g Loctite Duro-TAK 222A (solids content: 41%), 0.3g PEG400(Sigma Aldrich) and 0.29g ethyl acetate were mixed in a conditioning mixer for 3 minutes at 2000 rpm.

Example 18

4.88g of Loctite Duro-TAK 222A (solids content: 41%) and 0.1g of 1-ethyl-3-methylimidazolium ethyl sulfate were mixed in a conditioning mixer at 2000rpm for 3 minutes.

Example 19

4.15g Loctite Duro-TAK 222A (solids content: 41%), 0.3g PEG400, 0.1g 1-ethyl-3-methylimidazolium ethyl sulfate and 0.43g ethyl acetate were mixed in a conditioning mixer at 2000rpm for 3 minutes.

The mixture (table 6) was coated onto a release liner and dried at room temperature for 30 minutes, yielding a PSA film with a thickness of 20 μm. Subsequently, the coating film was cured at 120 ℃ for 3 minutes and covered with another release liner.

Table 6: DURO-TAK 222A PEG400 blends with or without EMIM ethyl sulfate

For impedance measurements (fig. 4), the dry PSA film was transferred onto Al foil. Two pieces of PSA-Al film were cut and glued together to form a film having 0.25cm²Area and 40 μm PSA thickness. Potentiostat from Metrohm Autolab at 9X 10⁵The impedance is measured in the frequency range to 0.1 Hz.

Examples 20 to 22

Addition of carbon black to ion-conductive pressure sensitive adhesives

Example 20

9.79g Loctite Duro-TAK 222A (solids content: 41%) and 0.22g choline acetate were mixed in a conditioning mixer at 2000rpm for 3 minutes.

Example 21

0.45g of carbon black (C-Nergy Super C65) and 1.36g of butyl acetate (3 minutes, 3500rpm) were mixed in a flash mixer using glass beads to prepare a paste. 9.32g Loctite Duro-Tak 222A were added in each 0.5g addition step. After each PSA addition step, the composition was mixed in a flash mixer for 1 minute at 3500 rpm. Subsequently, 0.23g choline acetate was added and mixed in a conditioning mixer at 2000rpm for 3 minutes.

Example 22

0.70g of carbon black (C-Nergy Super C65) and 2.5g of butyl acetate (3 minutes, 3500rpm) were mixed in a flash mixer using glass beads to prepare a paste. 9.07g Loctite Duro-Tak 222A was added in each 0.5g addition step. After each PSA addition step, the composition was mixed in a flash mixer for 1 minute at 3500 rpm. Subsequently, 0.23g choline acetate was added and mixed in a conditioning mixer at 2000rpm for 3 minutes.

The mixture (table 7) was coated onto a release liner and dried at room temperature for 30 minutes, yielding a PSA film with a thickness of 20 μm. Subsequently, the coating film was cured at 120 ℃ for 3 minutes and covered with another release liner.

TABLE 7 DURO-TAK 222A containing choline acetate and varying amounts of carbon black

For impedance measurements (fig. 5), the dry PSA film was transferred onto Al foil. Two pieces of PSA-Al film were cut and glued together to form a film having 0.25cm²Area and 40 μm PSA thickness. Potentiostat from Metrohm Autolab at 9X 10⁵The impedance is measured in the frequency range to 0.1 Hz.

Example 23

Impedance of counter electrode with dry electrode binder of ionic liquid combination

5g of LOCTITE Duro-TAK 222A (solids content: 41%) and 0.171g of 1-ethyl-3-methylimidazolium triflate and 0.057g of 1-ethyl-3-methylimidazolium chloride were mixed in a conditioning mixer at 2000rpm for 3 minutes. The mixture was coated onto a release liner and dried at room temperature for 30 minutes, resulting in a PSA film with a thickness of 20 μm. Subsequently, the coating film was cured at 120 ℃ for 3 minutes and covered with another release liner.

For impedance measurements, electrodes were prepared by transferring dry PSA films to TPU substrates coated with Ag/AgCl layers (Loctite EDAG 6038E SS from Henkel). The cut has a length of 3.1cm²Electrodes of area and connected to each other to form a cathode having 3.1cm²Area and 40 μm PSA thickness. The electrode pairs were connected with alligator clips and potentiostats from Metrohm Autolab at 9X 10⁵The impedance of the capacitor is measured in the frequency range to 0.01 Hz.

Fig. 6 illustrates impedance spectra of electrodes with dry adhesive compositions according to example 23 (solid line) and example 5 (dotted line). The impedance spectrum of the electrode with the Ag/AgCl conducting layer without chloride in the binder shows a strong capacitance increase at low frequencies corresponding to the presence of the blocking electrode and thus a high DC resistance, since (almost) no charge transfer over the whole interface of electrode/binder takes place. In contrast, an electrode with a chloride containing binder allows for a reaction between the Ag/AgCl conductive layer and the electrode binder, resulting in charge transfer (at a suitably low voltage), and thus a low DC resistance, which enables a fast discharge During (DOR) defibrillation overload recovery experiments.

Defibrillation overload recovery was tested for examples 4,5 and 13. In this test, the voltage of different electrode binder compositions (example 5 (round), example 13 (square), example 4 (triangle)) was measured over time during discharge. Fig. 7 shows the voltage on the electrodes during discharge. For examples 5 and 13, the voltage was always above 100mV, indicating that no sufficient discharge occurred (condition 2 loss — after 7 seconds < 100mV in table 7), while sample 4 easily passed the test requirements.

Fig. 8 illustrates three consecutive defibrillation overload recovery discharge curves according to ANSI/AAMI EC12:2000/(R)2015 for an electrode pair having an electrode adhesive according to example 5. A summary of the test conditions for the electrode pairs having electrode binders according to example 5 is illustrated in table 8 below. Three of the four requirements were not met, indicating the need for adhesives that allow for faster discharge.

TABLE 8

Fig. 9 illustrates three consecutive defibrillation overload recovery discharge curves according to ANSI/AAMI EC12:2000/(R)2015 for an electrode pair having an electrode adhesive according to example 23. A summary of the test conditions for the electrode pairs having electrode binders according to example 23 is illustrated in table 9 below.

TABLE 9

Here, all requirements are met showing the benefit of adding an ionic liquid with chloride as anion enabling DC conduction.

ANSI/AAMI EC12:2000/(R)2015 describes the use time of the electrodes to be limited to the time that the sample (two electrodes connected to each other via the adhesive side) can be biased with a 200nA current at a resulting voltage of < 100 mV. DC offsets of > 100mV should not be measured. This value is related to the start of the current bias curve.

Fig. 10 illustrates the voltage increase during current biasing for electrode samples with different binder compositions according to the present invention: example 23-solid line and example 5-dotted line.

Example 23 corresponds to a sample having DC conductivity. The voltage is defined by ohm's law. The voltage can be maintained for a long time. Since DC conductivity corresponds to a reversible electrochemical reaction at the interface, the voltage will remain relatively constant as long as the reactant is available at the interface. Example 5 does not provide significant DC conductivity at the interface. Thus, the voltage corresponds to the interface capacitance charging and thus increases significantly over time.

Electrodes that provide DC conductivity also exhibit longer current bias tolerance (current bias tolerance) and lower DC offset values. Preferably, the electrode binder exhibits DC conductivity and low impedance.

Fig. 11 illustrates the voltage increase during long-term current biasing (200nA) for an electrode sample (example 23) having an electrode binder according to the present invention.

Due to the long measurement time, the voltage is not recorded continuously here, but only measured several times a day (intermittent on weekends). Sample F, E, C, G corresponds to the nominally identical sample that has been current biased when in series. Thus, as expected, the results are very similar. The initial change (DC offset) disappeared after two days, resulting in a plateau. After about 5 days, the voltage started to rise. However, the voltage is still well below the required limit of 100 mV. Thus, the test is clearly acceptable for 8 day measurements (and most likely also acceptable for longer periods of time).

Fig. 12 illustrates the voltage increase during long-term current bias (2 μ Α) for the electrode sample with electrode binder (example 23).

2 μ a corresponds to ten times the current required by the specification. The test is intended to determine (qualifying) acceleration tests. The results roughly correspond to the increase that occurs in 40-45 hours. A higher current is considered (and the relevant value is considered to be the flowing charge), which would correspond to 6 days in normal testing (of which 5 days are visible). The voltage here is higher due to ohm's law (and therefore the onset of the increase can be hidden).

ANSI/AAMI EC12:2000/(R)2015 requires a peak-to-peak voltage of less than 150 μ V (after 1 minute stabilization) to ensure a low noise ECG signal. The AC signal recorded via the ECG system for electrode samples with electrode binder typically has a peak-to-peak voltage below 10 μ V.

Fig. 13 illustrates offset instability (offset instability) and internal noise measurements of an electrode sample (example 23) having an electrode adhesive according to the present invention.

The measurements correspond to ECG measurements through the interconnected electrodes rather than the human body. The total bandwidth is about 8 μ V and is therefore much lower than the (150 μ V) required in the specification.

Example 24

Impedance of a counterelectrode containing a dry electrode binder having varying degrees of OH functionality

Impedance of a counter electrode with a dry electrode binder according to the invention comprising 10 wt% EMIM-salt and a (meth) acrylate resin comprising different amounts of (meth) acrylate monomers comprising OH-groups; the following quantities according to the invention were tested: 15.0 wt%, 18.8 wt%, 22.5 wt%, 30.0 wt%, and 50.0 wt%, and compared to amounts 0 wt% and 7.5 wt%. Resistance values were normalized to a film thickness of 30 μm and 4cm²The area of (a). The test results are illustrated in fig. 14.

Fig. 14 shows the impedance curve of the adhesive described above. The general trend is that for higher OH content the impedance curve is shifted to lower values, indicating an increased suitability for ECG applications.