BRPI0616505B1 - CONDUCTIVE ADHESIVE COMPOSITION AND BIOMEDICAL ELECTRODE - Google Patents

Description

CONDUCTIVE ADHESIVE COMPOSITION AND BIOMEDICAL ELECTRODE This invention relates to conductive adhesive compositions and biomedical articles incorporating such conductive adhesive compositions.

Background Medical therapeutic and diagnostic procedures utilize equipment capable of processing electrical signals or electrical currents that are received from a patient's body or sent to the patient's body. In these procedures, the interface between the patient's skin and applicable equipment typically includes a biomedical electrode constructed to include a conductor electrically connected to medical equipment and a conductive medium that is adapted to contact the patient's skin (eg. by means of an adhesive).

By way of example, biomedical electrodes are employed in therapeutic procedures and equipment such as transcutaneous electrical nerve stimulation (ETNS) devices that are used for pain management, neuromuscular stimulation techniques (ENM) for the treatment of certain conditions such as scoliosis, defibrillation electrodes that serve to send electrical energy to the patient's pectoral cavity for the purpose of defibrillating the heart, and dispersive electrodes that receive the electrical energy that was applied to an incision made during an electrosurgery. Biomedical electrodes are also used in diagnostic procedures and equipment including electrocardiography to monitor cardiac activity and diagnose cardiac anomalies.

Non-polarizable electrodes and, in particular, electrodes made of silver and / or silver chloride are highly stable and have been widely used in diagnostic applications. In low-cost versions, these electrodes are often coated in thin sections of conductive paint over an insulating backing layer. Conductive inks formulated for these applications typically include silver or silver chloride particles and a polymeric binder. A cordive adhesive (e.g., a hydrogel or hydrocolloid) is applied to the silver-coated backing layer, and the assembly is die cut to achieve the desired electrode shape. The conductive adhesive serves to provide electrode adhesion to the skin as well as to allow electrical transduction of the electrical activity of the heart. The adhesive layer of the electrodes is protected by a removable strip before applying the electrode to the skin.

[005] Monolithic adhesive construction of typical nonpolarizable electrodes has been problematic due to the existence of an exposed adhesive edge along the perimeter of the electrode. The ionically conductive phase of the adhesive consists of an alkaline or alkaline earth metal chloride (typically potassium chloride or sodium chloride) dissolved in water with an optional humectant added to slow evaporative losses. However, under low humidity conditions (which can be as low as 20% in hospitals), rapid evaporative water losses occur with the consequent degradation of electrode electrical properties. The electrical properties are related to the conductance of the salt dissolved in the water and adhesive wetting mixture. As water evaporates, the concentration of humectant increases. Because alkaline and alkaline earth halides have unsatisfactory solubility in commonly used humectants, ionic concentration of the adhesive is compromised and electrical properties degrade.

There is a need for improved conductive adhesives and articles comprising such adhesives, including biomedical articles, for example, biomedical electrodes.

Summary The present invention provides conductive adhesives and articles comprising such adhesives. In one aspect, the invention features a conductive adhesive composition comprising (a) pressure sensitive adhesives; (b) electrolytes comprising a water-soluble or water-dispersible organic chloride: and (c) humectants. In another aspect, the invention provides a biomedical electrode comprising: a conductive element; and a conductive adhesive composition associated with the conductive element, the conductive adhesive composition comprising: (a) pressure sensitive adhesives; (b) electrolytes comprising water-soluble or water-dispersible organic chlorides; and (c) humectants.

For use in the present invention, "onio" cations refer to polyatomic cations formed by the addition of more protons than necessary to monatomic anions to obtain a neutral unit. These cations have names with the ending "onio". Substituted derivatives may be formed from basic cations, for example hydroxylammonium, tetramethylstibonium, dimethyl oxonium (CH3) 2OH +. Inorganic onion cations include "ammonium", "phosphonium", "oxon", "sulfonium", "chloronium", "bromonium" and "iodonium".

The terms "organic phase", "oil phase", "oleophilic phase", "hydrophobic phase" and "lipophilic phase" are used interchangeably in the present invention.

Those skilled in the art will better understand the features of the present invention by analyzing the remainder of the description of the present invention, including the Detailed Description, the various Figures, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS During the description of aspects of the embodiments presented, reference is made to drawings where structural features are identified by numerical references and where equal numbers indicate equal features.

[013] Figure 1 is a plan view of one embodiment of a biomedical electrode useful for diagnosis and monitoring of cardiac conditions in a mammalian patient, the electrode including a conductive adhesive in accordance with the present invention.

[2] Figure 2 is a cross-sectional view of the biomedical electrode of Figure 1.

Figure 3 is a plan view of one embodiment of a biomedical monitoring electrode useful for the diagnosis or long term monitoring of cardiac conditions, the electrode including a conductive adhesive in accordance with the present invention.

[016] Figure 4 is a cross-sectional view of the biomedical monitoring electrode of Figure 3.

Detailed Description The present invention provides conductive adhesives that can be used as electrically conductive components in an article, such as a biomedical article which includes, for example, a biomedical electrode. Conductive adhesives of the invention are resistant to losses of electrical properties accompanying moisture losses (e.g., water) of the adhesive. In embodiments of the invention, conductive adhesive is a pressure sensitive adhesive (ASP) comprising a chloride electrolyte. organic and a compatible humectant. In some embodiments, the conductive adhesive is a bicontinuous and conductive ASP having an aqueous phase and an oil phase with an organic chloride electrolyte, a compatible humectant and a surfactant in the aqueous phase. In some embodiments, the conductive adhesive is in the form of a hydrogel. In other embodiments, the ASP is a component of an article such as a biomedical electrode. The adhesive of the invention may be prepared according to a variety of processes. In some embodiments, the adhesive is prepared by a microemulsion having a viscosity suitable to cover a backing layer. The polymerized microemulsion ASP according to the present invention may be derived from the polymerization of hydrophilic monomers or oligomers and / or radically free polymerizable amphiphiles in an aqueous phase with the concomitant polymerization of radically free polymerizable hydrophilic and / or amphiphilic monomers or oligomers in an organic (oily) phase. The resulting ASP may have a bicontinuous structure which, in some embodiments, may comprise two substantially solid non-porous bicontinuous phases.

Bicontinuous Adhesive Compositions In embodiments of the invention, bicontinuous adhesive compositions are provided by polymerization of suitable monomers and / or oligomers provided as polymerizable microemulsion compositions. Prior to polymerization, the microemulsions typically include an aqueous phase comprising water, ethylenically (co) polymerizable hydrophilic or amphiphilic monomer (s) or amphiphilic (s) polymer (s). ) Radically free, initiators, organic chloride electrolytes, humectants, surfactants and optional additives. The organic or oily phase typically comprises ethylenically (co) polymerizable hydrophobic or amphiphilic unsaturated monomer (s) or oligomer (s). The microemulsion components can be added in any logical order. For example, the components may initially be combined into two or more separate mixtures. Starting mixtures may subsequently be combined to form a microemulsion. The components of a suitable microemulsion are discussed below.

Generally, microemulsion compositions comprise from about 2 to about 50 weight percent of water (e.g. deionized water). In some embodiments, the compositions comprise about 5 to about 30 weight percent, and in some embodiments, about 6 to about 25 weight percent, based on the total weight of the microemulsion. may include water soluble and / or dispersible additives selected to provide certain properties to the final ASP. In order to determine the percentage by weight of most suitable water to be included in the microemulsion, water may be incrementally added until a clear microemulsion region is reached.

Radically Free and Ethylenically Unsaturated Polymerizable Polar (Co) Species

At least one radically free polymerizable ethylenically unsaturated polar monomer or oligomer is included in the microemulsion. Suitable polar monomers or oligomers may be oil-insoluble (hydrophilic) or may be partially water-soluble and partially oil-soluble (amphiphilic) such that they may dissolve in or become associated with an aqueous phase. phase in the microemulsion. In some embodiments, the use of polar oligomers in the aqueous phase promotes the formation of a substantially non-porous bicontinuous structure to the polymerized microemulsion ASP.

Generally, monomers may be selected from the group consisting of polar monomers, which are substantially insoluble in the oil phase, and polar monomers in addition to the oil insoluble monomers (for example, polar monomers that are both water soluble and soluble in oil).

Typically, microemulsions will comprise from about 2 to about 90 weight percent of hydrophilic or amphiphilic monomers or oligomers. In some embodiments, the microemulsion will comprise from about 5 to about 70 weight percent, and in other embodiments, from about 10 to about 60 weight percent, based on the total weight of the microemulsion, depending on the properties. desired from the polymerized ASP.

Radically Free and Ethylenically Unsaturated (Co) Polymerizable Oligomers Radically free and ethylenically unsaturated (co) polymerizable oligomers, which are substantially insoluble in the oil phase, or are either water-soluble or non-oil soluble, a, polyethylene oxide acrylates, polyethylene oxide diacrylates, polyethylene glycol acrylates, polyethylene glycol diacrylates, polyurethane acrylates, polyurethane diacrylates, N-vinyl pyrrolide macromer and mixtures of two or more of these compounds previously In some embodiments, polyethylene oxide acrylates and diacrylates are used The oligomers may have a number average molecular weight of from about 100 to about 100,000. In some embodiments, the number average molecular weight may be in the range from about 100 to about 60,000, or from about 100 to about 5,000. Lecular lenses can be selected to provide an ASP with optimized physical properties (eg water absorption, pore age, strength).

Substantially Oil-Insoluble Polar Monomers. RADICALLY LONG AND ETHENICALLY UNSATURATED

An optional polar monomer for inclusion in the aqueous phase of a microemulsion consists of a water soluble radically free (co) polymerizable ethylenically unsaturated polar monomer that is substantially insoluble in the oil phase. For use in the present invention, the terms "substantially oil-insoluble" and "water-soluble" mean that the monomer has a solubility of less than about 0.5% by weight in the oil phase and exhibits a distribution ratio in a given temperature (preferably about 25 Ό to about 35 ° C) between the oil phase concentration and the water phase concentration less than about 0.005. Such a monomer may be nonionic, for example acrylamide, or this monomer may be ionic. Mixtures of nonionic and ionic monomers may also be used.

[026] Ionic monomers meeting the above criteria include, but are not limited to, sodium styrene sulfonate, potassium acrylate, sodium acrylate, sodium methacrylate, ammonium acrylate, 2-acrylamide. Sodium 2-methylpropane sulfonate, 4,419-trimethyl-4-azonyl-7-oxa-dec-9-ene-1-sulfonate, N, N-dimethyl-N- (beta-methacryloxyethyl ) betaine ammonium propionate, trimethylamine methacrylamide, amine 1,1-dimethyl-1- (2,3-dihydroxy propyl) methacrylamide, and other ethylenically unsaturated zwitterionic monomers having the indispensable requirements for solubility, mixtures thereof and the like. In some embodiments, oil-insoluble polar monomers include those selected from the group consisting of acrylamide, sodium styrene sulfonate, sodium acrylate, sodium 2-acrylamido-2-methylpropane sulfonate, sodium methacrylate, and mixtures thereof because of the ease of use. formulation and desirable properties when polymerized.

[027] In some embodiments, it may be desirable to limit the amounts of anionic monomers in order to avoid the possible in situ formation of alkali metal or alkaline earth metal chlorides, the presence of these could result in a loss of conductivity if adhesive lose moisture.

Other Rationally Free and Ethylenically Unsaturated Polarised (Co) Folomerizable Monomers Polar monomers may exhibit some solubility in both water and oil, which have a solubility of about 0.5% or more in the oil phase and a ratio of distribution at a given temperature (preferably about 25 ° C to about 35 ° C) between the concentration in the oil phase and the concentration in the aqueous phase greater than or equal to about 0.005. Useful radically free and ethylenically unsaturated polar (co) polymerizable monomers partitionable between the aqueous phase and the microemulsion oil phase include, but are not limited to, N-vinyl pyrrolidone, N-vinyl caprolactam, (meth) acrylic acid, (meth) ) hydroxy ethyl acrylate, itaconic acid, styrenesulfonic acid, N-substituted acylamides, N, N-disubstituted acrylates, α-β-dimethyl amino ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid, and mixtures thereof. In some embodiments, polar partitionable monomers include (meth) acrylic acid, N-vinyl pyrrolidone, N-vinyl caprolactam, β, β-dimethyl amino ethyl methacryl, β, β-dimethyl acrylamide, styrenesulfonic acid, 2-acrylamido-2- methyl propane sulfuric acid, and mixtures thereof.

In some embodiments, polar partitionable monomers may impart desired properties to biphasic polymeric powder with such monomers including acrylic acid, N-vinyl pyrrolidone, N-vinyl caprolactam, α, β-dimethyl acrylamide, and mixtures of the following. same.

WATER SOLUBLE INITIATORS

The microemulsion may optionally comprise a water soluble free radical polymerization initiator. In some embodiments, the primer is selected from the group consisting of thermal initiators, photoinitiators, and mixtures of the foregoing. Water soluble initiators dissolve in the aqueous phase of the microemulsion.

WATER SOLUBLE PHOTOINICIATORS

Water-soluble photoinitiators useful in the present invention include photoinitiators that generate free radicals upon exposure to electromagnetic (generally ultraviolet) radiation that initiates (co) polymerization of the hydrofflic monomer (s) of ( oleophilic monomer (s), polymerizable oligomers (co) and polymerizable surfactant as detailed below. Useful water-soluble photoinitiators include, but are not limited to, benzophenones substituted by an ionic moiety, a hydrophilic moiety or both, thioxanthones substituted by an ion moiety, a hydrophilic moiety or both and 4-substituted- (2). -hydroxy-2-propyl) phenyl ketones, wherein the 4-substituent is an ionic or hydrophilic moiety. Ionic or hydrophilic moieties include, but are not limited to, hydroxyl groups, carboxyl groups and groups of a carboxylic acid salt. Useful water soluble benzophenones include, but are not limited to, 4-trimethylamino methyl benzophenone hydrochloride and sodium benzophenone 4-methanesulfonate. Useful water-soluble thioxanthones include, but are not limited to, 3- (2-hydroxy-3-trimethylaminopropoxy) thioxanthone hydrochloride, 3- (3-trimethylaminopropoxy) thioxanthone hydrochloride, sodium salt 3- (2-acid ethoxy sulfonic) thioxantone and sodium salt 3- (3-propoxy sulfonic acid) thioxantone. Useful water-soluble ketones include, but are not limited to, (2-hydroxy-2-prapyl) {4-diethylene glycol phenyl) ketone, (2-hydroxy-2-propyl) (phenyl) 4-buttanocarboxyl) ketone, 4- (2-hydroxy ethoxy) phenyl (2-propyl) ketone, and their water-soluble salts. In some embodiments of the invention, the water soluble photoinitiator is 4-trimethyl amino methyl benzophenone hydrochloride. In some embodiments, mixtures of the aforementioned compounds may be used.

The aqueous phase of the microemission may comprise about 0.05 to about 1 part by weight of a photoinitiator, and in some embodiments about 0.1 to about 1 part by weight based on 100 parts by weight of the total (co) polymerizable species in the microemission.

Water Soluble Thermal Primers The water soluble thermal initiators useful in the present invention include those which upon exposure to heat generate free radicals which initiate the (co) polymerization of the hydrophilic monomer (s). , the oleophilic monomer (s), the polymerizable oligomer (s) and, where present, the polymerizable surfactant discussed herein. Suitable water soluble thermal initiators include, but are not limited to, potassium persulfate, ammonium persulfate, sodium persulfate, and mixtures thereof, oxidation-reduction initiators, such as the reaction product of the above-mentioned persulfates and reducing agents, as sodium metabisulphite and sodium bisulphite and 4,4'-azobis (4-cyanopentanoic acid) and their soluble salts (eg sodium, potassium). In some embodiments, the water-soluble thermal initiator is ammonium persulfate. Mixtures of two or more of the aforementioned compounds may be used.

Typically, water soluble thermal initiators are used at temperatures in the range of about 50 ° C to about 70 ° C, while oxidation-reduction type initiators are used at temperatures of about 30 ° C to about 70 ° C. 50 ° C. Water soluble thermal initiators may comprise from about 0.05 to about 1 part by weight, and in some embodiments from about 0.1 to about 1 part by weight, based on 100 parts by weight. , of the (co) polymerizable species in the microemulsion composition.

Water Soluble Electrolytes The electrical conductivity of the ASPs of the invention is accomplished by the inclusion of a water soluble electrolyte. Electrolytes useful in the present invention include organic chloride electrolytes that facilitate the electrical conductivity of the resulting ASP. In addition, organic chloride electrolytes, when coupled with a miscible humectant, provide resulting ASPs with the ability to withstand and even prevent a drastic reduction in electrical conductivity through loss of water or moisture from the finished ASP. In embodiments of the invention, up to about 10 parts by weight of the organic chloride electrolyte may be present. In some embodiments, the electrolyte may be included in a concentration in the range of from about 0.5 parts by weight to about 5 parts by weight based on 100 parts by weight of the total aqueous phase of the microemulsion.

[036] In the embodiments of the invention, the organic chloride electrolyte comprises one or more onium chlorides. In some embodiments, onium chloride comprises at least one ammonium chloride (e.g., quaternary ammonium chloride). In some embodiments, onium chloride comprises at least one phosphonium chloride. In other embodiments, the onium chloride may comprise oxonium chloride or sulfonium chloride. Mixtures of two or more organic chlorides, including the above-mentioned onium chlorides, may also be used. In modalities where the electrolyte is ammonium chloride, a useful class of organic chlorides is the class of quaternary ammonium chloride, which may include, but is not limited to, hydroxyethyl trimethyl ammonium chloride (also known as ammonium chloride). choline), a naturally-occurring salt that is endogenously produced in humans and forms a key component of the lipid bilayer in human cells. [037] In some embodiments, quaternary ammonium chloride electrolytes include those selected from from the above-mentioned ethyl trimethylammonium hydroxy chloride (choline chloride), as well as from benzyl trimethylammonium chloride, benzyl triethylammonium chloride, tetraethylammonium chloride, acetamidopropyl trimethylammonium chloride, trimethylammonium chloride dodecylammonium trimethylammonium chloride , trimethylammonium chloride octadecii, trimethylammonium chloride beenii, c coconut alkyl trimethylammonium chloride, tetradecyl dimethyl benzylammonium chloride, almond amidopropalconium chloride, avocado amidopropylchloride, ethyl tallow bishydroxy chloride, dibeenyl diammonium chloride, diocoil diammonium chloride , diammonium chloride (soy dialkyl), diammonium chloride (dimethyl dialkyl tallow), diethylammonium chloride PPG-9, diethyl ammonium chloride PPG-9, ethyl hexyl diammonium stearyl chloride. Combinations of two or more of the above-mentioned compounds are also contemplated within the scope of the invention.

Humectant The ASP of the invention comprises one or more humectants. In embodiments of the invention at least one humectant will be compatible with the organic chloride electrolyte (s), where the humectant and the electrolyte (s) ) will be miscible with each other. In other respects, the humectants and electrolytes will be at least partially miscible with each other. In embodiments of the invention, the selected humectant is a humectant capable of retaining moisture in the ASP. In the aspects of the aforementioned embodiments, the humectant is miscible, or at least partially miscible, with the organic chloride electrolyte to the extent that the humectant is capable of retaining the electrolyte in the ASP after moisture loss (e.g., by loss of moisture). evaporative conditions in low relative humidity environments) and thus avoid an acute degradation of electrical conductivity.

Suitable humectants for use in conductive AS Ps of the present invention include polyhydric alcohols, such as glycerine, propylene glycol, dipropylene glycol, 1,3-butane diol, 1,4-butane diol, trimethylol propane, ethylene glycol and combinations of two or more of the aforementioned compounds. Generally, suitable humectants are described by the formula: M0 (CH2 CH20) m H where M is selected from the group consisting of hydrogen and G (-C6 alkyl), and m is an integer from about 1 to about 25.

Optional Water Soluble Additives The microemulsion may optionally further comprise a number of water soluble additives associated with the aqueous phase of the microemulsion for the purpose of producing a polymerized microemulsion ASP having specific properties and / or appearance. Each additive is selected for the purpose of producing a desired end product. Examples of useful additives include, but are not limited to, water soluble crosslinkers (such as methylene bisacrylamide), plasticizers (such as glycerin and polyalkylene glycols), pH adjusters, other electrolytes, dyes, pigments, pharmaceutically active compounds, physiologically compounds. actives, cosolvents, non-polymerizable polar oligomers, mixtures thereof, and mixtures of two or more of the foregoing compounds.

[041] Non-polymerizable * (co) polymerizable oligomers useful as additives include, but are not limited to, poly (N-vinyl pyrrolidone), polyethylene glycols, poly (oxyethylene) alcohols, poly (etholimine), and mixtures of two. These oligomers may be added for the purpose of affecting the volume properties of the resulting polymerized microemulsion ASP, for example to impart hydrophilic properties to the material. [042] Co-solvents may also be included in the microemulsions of the present invention. Such cosolvents include aliphatic alcohols having from about 1 to about 8 carbon atoms (such as glycerine), polyethers (such as those available under the tradename BUTYL CELLOSOLVE, BUTYL CARBITOL, HEXYL CALLOSOLVE, and HEXYL CARBITOL, all commercially available from Union Carbide). ), and mixtures of two or more of the above compounds, It will be recognized that essentially all water-soluble organic additives which are added to the aqueous phase will exhibit a degree of solubility in the organic phase of the microemulsion, and that Each additive will have its own distribution ratio between the aqueous phase and the organic phase. Except where otherwise specified, the above-mentioned aqueous phase constituents will be provided with and will also affect the properties of the organic phase. It is not necessary for the understanding and practice of the present invention to quantify the particular distribution ratio of all additives mentioned herein.

Hydrophobic Components Prior to polymerization, the oil phase of the inventive microemulsion compositions may comprise radically free (co) polymerizable monomers and / or oligomers suitable for forming a hydrophobic homopolymer or copolymer of the pressure sensitive adhesive, radically free polymerizable (co) polymerizable monomers, hydrophobic initiator and optional reactive lipophilic additives.

Radically Free Hydrophobic (Co) Polymerizable Monomers Radically free and ethylenically unsaturated hydrophobic polymerizable monomers useful in the lipophilic phase of the myoemulsions of the present invention include, but are not limited to, those selected from the group consisting of about C1 to about C1-8. alkyl esters of acrylic acid, i.e. those esters derived from acrylic acid and from about C1 to about Cys, provided that such monomers are suitable for formation of a hydrophobic polymer having pressure sensitive adhesive properties.

[046] The glass transition temperature (Tg) of the polymerized microemulsion ASP may be determined by the use of known techniques, and the Tg of a polymerized microemulsion ASP is determined in part by the selection of hydrophobic monomers used in the formation of a hydrophobic polymer with pressure sensitive adhesive properties. A Tg less than about 10¾ will often be associated with a hydrophobic polymer that has the properties of the pressure sensitive adhesive, and a Tg less than about 0¾ will most often be associated with a hydrophobic polymer that has the properties of the pressure sensitive adhesive. pressure sensitive adhesive. Even more often, a Tg less than about -10¾ will be associated with a hydrophobic polymer that has the properties of the pressure sensitive adhesive. In some embodiments, alkyl acrylates, including isooctyl acrylate, ethyl hexyl 2-acrylate and n-butyl acrylate are preferred because of their availability in use and because of the resulting hydrophobic polymer Tg formed from such hydrophobic monomers. .

The organic phase may optionally further comprise radically free and ethylenically unsaturated polymerizable comonomers which are co-polymerizable with the alkyl acrylate monomers described above for the purpose of modifying the ASP glass transition temperature (Tg) of resultant polymerized microemulsion from the Tg contributed by the hydrophobic monomer (s). Suitable comonomers include styrene, acrylonitrile and vinyl esters (such as vinyl acetate, vinyl propionate and vinyl neopentanoate, etc.) and combinations thereof. The selection of the comonomer (s) may depend on the desired properties of the final solid bicontinuous polymer.

The polymerized micromemulsion AS Ps of the invention generally comprise from about 5 to about 80 weight percent of hydrophobic monomers, typically from about 10 to about 70 weight percent, and, in some embodiments, about 12 to about 60 weight percent, based on the total weight of the microemulsion, in order to impart sufficient strength, adhesion and pressure sensitive adhesive properties to the polymerized microemulsion ASP. Actual concentrations of each microemulsion constituent may be altered by the skilled artisan depending on the desired properties of the copolymer pressure sensitive adhesive.

Free Radicaljmehte (Co) Polymerizable Polar Monomers The organic phase of a microemulsion will typically contain a portion of the radically free polymerizable amphiphilic polar monomers described above because of the partition of these organic materials between the aqueous phase and the organic phase. of a microemulsion as described above. Those skilled in the art will appreciate that each monomer will exhibit its own distribution ratio, the enumeration of which is not necessary for the understanding and practice of the present invention.

HDBOBOBIC INITIATORS

The oil phase of the microemulsion may optionally further comprise a hydrophobic free radical polymerization initiator.

In some embodiments, the initiator is selected from the group consisting of thermal initiators, photoinitiators, and mixtures of the above, Hydrophobic Photoinitiators [051] Generically, hydrophobic photoinitiators include those that generate free radicals upon exposure to electromagnetic (usually ultraviolet) radiation. initiating the (co) polymerization of the hydrophilic monomer (s) and / or oligomer (s), the oleophilic monomer (s) and the polymerizable active tension (co). Useful photoinitiators include, but are not limited to: (1) mixtures of Michler ketone and benzyl or benzophenone, preferably in a weight ratio of about 1: 4; (2) coumarin-based photoinitiating systems as described in U.S. Patent No. 4,289,844, incorporated herein by reference; and (3) dimethoxy phenyl acetophenone and / or diethoxy acetophenone based systems.

[052] Hydrophobic photoinitiators are initially included in microemulsions as part of the organic phase. Under irradiation, free radicals thus generated the effect of (co) polymerization of monomers in both the aqueous and organic phases, as well as the copolymerization of any (co) polymerizable surfactant. In some embodiments, the organic phase of a microemulsion will comprise from about 0.01 to about 5 parts by weight of an oil soluble photoinitiator based on 100 parts by weight of the total (co) polymerizable species in the art. microemulsion.

Optional Hydrophobic Thermal Primers [053] Hydrophobic thermal initiators may optionally be used in the preparation of the bicontinuous polymers of the present invention following the photopolymerization step as described above for the purpose of completing the polymerization reaction.

Hydrophobic thermal photoinitiators include those which generate free radicals upon exposure to heat which initiate the (co) polymerization of hydrophilic monomer (s) and / or hydrophilic oligomer (s). ) oleophilic monomer (s) and, where present, the polymerizable surfactant (co) as detailed below. Suitable hydrophobic thermal initiators include, but are not limited to, those selected from the group consisting of azo compounds, such as 2,2'-azobis (isobutyronitrile), available under the tradename VAZO 64 from DuPont, 2,2'-azobis (2,4-dimethyl pentanenitrile), commercially available under the tradename VAZO 52, peroxides such as benzoyl peroxide and lauroyl peroxide, and mixtures of two or more of the aforementioned compounds.

The organic phase of a microemulsion may comprise about 0 to about 5 parts by weight of a hydrophobic thermal initiator, typically about 0.05 to about 5 parts by weight, and in some cases. embodiments, about 0.1 to about 5 parts, based on 100 parts of the total weight of microemulsion (co) polymerizable compounds.

Optional Reactive Lipophilic Additives Microemulsions may further comprise one or more additional radically free reactive constituents, including, but not limited to, hydrophobic crosslinking agents, chain transfer agents, and mixtures thereof. will be present in the oil phase of the microemulsion. Examples of useful crosslinking agents include, but are not limited to, those selected from the group consisting of divinyl benzene, about C4 to about C8 alkyl diacrylates, such as butane 1,4-diacrylate diol, 1,6-diacrylate. hexane diol, octane diol 1,8-diacrylate and mixtures thereof. In some embodiments, the crosslinking agent is hexane diol 1,6-diacrylate. The crosslinking agent, if added, alters physical properties such as the endurance of the final polymer.

The oil phase may optionally further comprise from about 0 to about 10 or more parts by weight of the crosslinker, typically about 0.1 to about 2 parts by weight based on in 100 parts by weight of the total oil phase. The amount of crosslinker used will determine the physical properties of the polymer, such as its solubility (or insolubility) in certain solvents, its modulus, and its internal strength.

The microemulsion may further comprise an oil phase soluble chain transfer agent. Examples of useful chain transfer agents include carbon tetrabromide, alcohols, mercaptans, and mixtures thereof. In some embodiments, the chain transfer agent is isooctyl thioglycolate. The oil phase may comprise up to about 0.5 parts by weight of a chain transfer agent, typically about 0.01 to about 0.5 parts by weight, and, in some embodiments, about 0.05 parts by weight to about 0.2 parts by weight based on 100 parts by weight of the total oil phase.

Optional Non-Reactive HiDRQPHOCK Additives [059] The microemulsion may optionally further comprise one or more non-reactive hydrophobic additives. A variety of hydrophobic additives may be included in the microemulsion. These materials are added for the purpose of producing a final polymer system with specific physical properties or appearance. Examples of such optional additives include, but are not limited to, those selected from the group consisting of plasticizers, such as one of the phthalate esters well known in the art. The oil phase may optionally further comprise about 0 to about 20 parts by weight of a plasticizer, in some embodiments about 5 to about 20 parts by weight, and typically about 8 parts. to about 15 parts by weight based on 100 parts by weight of the oil phase.

Surfactants Nonionic and ionic surfactants (anionic and cationic) may be employed in the present invention. The surfactant (s) may be co-polymerizable with the monomers present in the microemulsion, or the surfactant. may be non - (co) polymerizable. In some embodiments, the surfactant (s) is (co) polymerizable such that the resulting polymerized microemulsion is less sensitive to water. Where water resistance is not required, inexpensive non-(and co-effective) surfactants may be used.

Nonionic Surfactants Typically, nonionic surfactants are products of the condensation of an organic aliphatic or hydrophobic aromatic alkyl compound and an alkylene oxide such as ethylene oxide, which is hydrophilic. Hydrophobic compounds having a carboxy, hydroxy, starch or amino group with a free hydrogen present can generally be condensed with ethylene oxide for the purpose of forming a nonionic surfactant. The length of the ethylene oxide chain of the condensation product may be adjusted to achieve the desired balance between hydrophobic and hydrophilic elements (Hydrophilic-Lipophilic Equilibrium or EHL). The EHL of a surfactant is an expression of the equilibrium of the size and resistance of the hydrophilic (hydrophilic or polar) and lipophilic (oleyophilic or nonpolar) groups of the surfactant. The useful EHL of nonionic surfactants of the present invention for preparing microemulsions is from about 6 to about 19, typically about 9 to about 18, and, in some embodiments, about 10 to about 16. Surfactants Useful nonionic surfactants include non-(co) polymerizable nonionic surfactants, ethylenically unsaturated co-polymerizable nonionic surfactants and mixtures thereof, Non-(Co) nonionic surfactants [062 Particularly suitable non-reactive nonionic surfactants include the products of the condensation of a larger alitactic alcohol, such as a fatty alcohol, containing about 8 to about 20 carbon atoms, in a straight or branched, condensed chain configuration. with about 3 to about 100 moles, typically about 5 to about 40 moles, in some embodiments, about 5 to about 20 moles of ethylene oxide to achieve the EHL defined above. Examples of such nonionic fatty acid alcohol surfactants are those available under the trade names TERGITOL 15-S from Union Carbide and the BRIJ surfactants available from ICI. TERGITOL 15-S surfactants include Gn -C15 secondary ethers of polyethylene glycol alcohol. Tensoactivo BRIJ 58 is polyethylene skeptical ether (20) and Tensoactivo BRIJ 76 is polyoxyethylene stearyl ether (IG).

Other suitable non-reactive nonionic surfactants include one phenol alkyl phenol polyethylene oxide condensates containing from about 6 to 12 carbon atoms in a straight or branched chain configuration, from about 3 to about 100 moles, typically about 5 to about 40 moles, in some embodiments, about 5 to about 20 moles of ethylene oxide to achieve the EHL defined above. Examples of nonreactive nonionic surfactants are those available under the IGEPAL GO and CA series trade names from Rhone Poulenc. IGEPAL GO surfactants include nonylphenoxy poly (ethylene oxy) ethanols. IGEPAL CA surfactants include poly (ethylene oxy) octylphenoxy ethanols.

Another group of useful non-reactive nonionic surfactants includes ethylene oxide block propylene oxide copolymers with EHL values from about 6 to about 19, typically about 9 to about 18, and in some embodiments from about 10 to about 16. Examples of such block copolymer nonionic surfactants are the PLURONIC and TETRONIC surfactant series available from BASF. PLURONIC surfactants include block copolymers of ethylene oxide and propylene oxide. TETRONIC surfactants include block copolymers of ethylene oxide and propylene oxide.

Other satisfactory non-reactive nonionic surfactants include, but are not limited to, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyethylene stearates having about 6 to about 19 EHLs, typically, from about 9 to about 18, and in some embodiments from about 10 to about 16. Examples of such nonionic fatty acid ester surfactants are those available under the trade names SP AN, TWEEN and MYRJ from to ICI, SP AN surfactants include C 12 -C 18 sorbitan monoesters. TWEEN surfactants include C12 - C18 poly (ethylene oxide) sorbitan monoesters. MYRJ surfactants include poly stearates (ethylene oxide).

Ethylenically Unsaturated Co-polymerizable Nonionic Surfactants Nonionic surfactants suitable for incorporation into polymerizable microemulsion compositions of the invention include the ethylenically unsaturated co-polymerizable nonionic surfactants which include, but are not limited to, those which are included in the general formula: R-O- (R'0) m - (EO) (n-ij -CH 2 CH 2 OH) where: R consists of (C 2 -C 10) alkenyl, acryl, (C 1 -C 10) alkylmethyl methacrylyl (C1 -C10) methacrylyl (C 1 -C 10) alkyl, vinylphenyl and (C 1 -C 6) alkylphenylene; R 'O consists of bivalent alkylene oxy groups derived from epoxy compounds having from two to four carbon atoms (eg ethylene oxide propylene oxide, butylene oxide and combinations) E is a bivalent ethylene radical m and m may be the same or different, each representing an integer in the range of about 5 to about 100 with the ratio m / m n in the range of about 20: 1 to about 1: 2 0

For the aforementioned surfactants, the variation of the ratio between m and n will vary the EHL of the polymerizable surfactant. In embodiments of the invention, the EHL of nonionic surfactant (s) ranges from about 6 to about 19, typically about 9 to about 18, and, in some embodiments, about 10 to about 18. 16. Examples of suitable copolymerizable nonionic surfactants are alkylene ethanol polyalkoxy surfactants available from PPG Industries under the tradename MAZON BSN 185, 186 and 187. MAZON BSN surfactants include alkylene ethanol polyalkoxy.

Anionic Surfactants [068] Anionic surfactants include a hydrophobic moiety selected from alkyl, alkyl aryl and (C6 -C20) alkenyl groups and an anionic group selected from polyoxyethylene sulfate, sulfonate, phosphate, sulfonate, ethylene polyoxy, polyoxyethylene phosphate and alkali metal salts, warm salts, and tertiary amino salts of these anionic groups. In some embodiments, an ethylenically unsaturated (co) polymerizable surfactant includes (C 2 -C 8) polyoxy propylene or (C 2 -C 18) alkenyl polyoxybutylene as a hydrophobic moiety and an anionic group of polyoxyethylene sulfate for preparing microemulsions.

[069] In some embodiments of the invention, nonreactive anionic surfactants and / or ethylenically unsaturated copolymerizable anionic surfactants may be used as discussed herein.

Non-Reactive Anionic Surfactants Non-reactive anionic surfactants suitable for use in the present invention include alkyl or alkyl aryl (G§ a Cao) * sulfates or sulfonates such as sodium lauryl sulfate (e.g., commercially available under trade name POLYSTEP B-3 from Stepan Co. of Northfield, IL, USA) and dodecyl benzene sodium sulfonate (for example, commercially available under the tradename SIPONATE DS-10 from Rhone Poulenc of Cranbury, NJ, (USA) alkylene phenol (C6 to C20) polyoxyethylene ether sulfates with the ethylene oxide repeating unit in the surfactant below about 30 units, typically below about 20 units, and in some embodiments, below about 15 units, such as commercially available POLYSTEPA B1 from Stepan Co. and ALIPAL EP110 and 115 available from Rhone Poulenc, alkyl or alkyl phenyl poly (ethylene-oxy) monoesters and diesters (Ce to C20) of the phosphoric acid and its salts, with the repeat unit of ethylene oxide in the surfactant below about 30 units, typically below about 20 units, and in some embodiments below about 15 units, such as those commercially available under the tradename GAFAC PE-510 and GAFAC RE-610 from GAF of New York, NY, USA, Ethylenically Unsaturated Co-Polymerizable Anionic Surfactants [071] In the embodiments of the invention, anionic surfactants for Incorporation into microemulsion compositions include, but is not limited to, ethylenically unsaturated copolymerizable surfactants of the following formula: wherein: R 1 consists of C 2 to C 18 alkenyl, acrylyl, C1 -C10 acrylyl alkyl, methacrylyl, (C1 -C10) methacrylyl alkyl, vinylphenyl and vinylphenylene (C1 -C6) alkyl; R 2 O is selected from the group consisting of bivalent alkylene groups derived from epoxy compounds having more than two carbon atoms, preferably three or four carbon atoms, such as propylene oxide and butylene oxide and mixtures thereof. alkylene oxy; E is a bivalent ethylene radical; m and n may be the same or different, each representing an integer in the range from about 5 to about 100 with the ratio m / n in the range from about 20: 1 to about 1; 20; and [072] X is an anionic group selected from the group consisting of sulfonate, sulfate, phosphate and alkali metal salts or ammonium salts or tertiary amino salts of these anionic groups, [073] It will be understood that the variation in the ratio of m and n will vary. the EHL of the polymerizable surfactant. The EHL for the anionic copolymerizable surfactants of the present invention, excluding those of group X, is typically about 3 to about 16. An example of a suitable copolymerizable anionic surfactant according to the above formula is that available. under the tradename MAZON SAM 211, commercially available from PPG Industries, Inc.

Cationic Surfactants Cationic surfactants may be useful in embodiments of the present invention. Useful cationic surfactants include quaternary ammonium salts, especially those in which at least one higher molecular weight group and two or three lower molecular weight groups are attached to a common nitrogen atom for the purpose of producing a cation, wherein the electrically balanced anion is selected from the group consisting of a halide (bromide, chloride, etc.), acetate, nitrite and lower alkosulfate (methosulfate etc.). The highest molecular weight substituent (s) on nitrogen is / are often (a) higher alkyl group (s) containing about 10 to about 20 carbon atoms, and the substituents of Lower molecular weight may be lower alkyl of about 1 to about 4 carbon atoms, such as methyl or ethyl, which may be substituted by hydroxy in some cases. One or more of these substituents may include an aryl moiety or may be substituted by an aryl such as benzyl or phenyl. Possible lower molecular weight substituents include lower alkyls of from about 1 to about 4 carbon atoms, such as methyl and ethyl, substituted by lower polyalkoxy moieties, such as polyoxyethylene moieties, which produce a final hydroxyl group, and which are included in the general formula: -R 3 (CH 2 CH 2) tr, -1) CH 2 CH 2 OH where: R 3 is a nitrogen-linked divalent C 1 to C 4 alkyl group; and n represents an integer from about 1 to about 15.

Alternatively, one or two lower polyalkoxy moieties having terminal hydroxyls may be directly attached to quaternary nitrogen rather than being attached thereto through the aforementioned lower alkyl.

Specific examples of quaternary ammonium halide surfactants suitable for use in the present invention include ammonium methyl bis (2-hydroxyethyl) ammonium chloride or oleoyl chloride, such as those commercially available under the tradename ETOQUAD C / 12 and 0/12, respectively. In addition, octadecyl methyl polyoxyethylene ammonium chloride (15) may be used, including 0 available under the tradename ETOQUAD 18/25 from Akzo Nobel Chemicals Inc. of Chicago, IL, USA. Combinations of two or more of the above-mentioned compounds may also be used.

Thickeners Agents useful in microemulsions according to the present invention include hydrophilic polymers formed partially or completely from the acrylic acid monomer. In some embodiments, acrylic acid homopolymers are useful, although hydrophilic acrylic acid copolymers, typically those containing at least about 20%, and in some embodiments at least 80% acrylic acid residues, are also useful. . The molecular weight of such thickening agents may be from about 200,000 to about 800,000, and in some embodiments is from about 400,000 to about 700,000.

Adhesive HYDROGELS [078] In the embodiments, the ASPs of the invention may be in the form of an adhesive hydrogel. Such a hydrogel may, for example, be an acrylate based single phase ASP. In some embodiments, the hydrogel may be prepared with an adhesive precursor resulting from the reaction of acrylic acid, 2-hydroxy ethyl methacrylate tetrakis (hydroxy methyl) phosphonic chloride, butylene glycol, glycerol, water, initiator (e.g. IRGACURE primer 2959) and polyethylene glycol diacrylate (400). The unreacted (e.g. unpolymerized) precursor may be coated on a removable strip as a substrate. Polymerization in the coated microemulsion is then stimulated by exposing the precursor to electromagnetic radiation (e.g., ultraviolet light) for a set period of time (e.g., 10 minutes or less) to initiate the polymerization reaction and thereby mode, to convert the coated precursor into a conductive adhesive.

Biomedical Articles [079] In the embodiments of the invention, the above conductive ASPs may be used as components of biomedical articles, for example, biomedical electrodes.

Biomedical Electrodes [080] Biomedical electrodes employing polymerized ASPs containing electrolytes are useful for diagnostic (including monitoring) and therapeutic purposes. In a basic form, a biomedical electrode comprises a conductive medium capable of contacting mammalian skin and a means for electrical communication between the conductive medium and electrical, therapeutic or electrosurgical diagnostic equipment. In embodiments, the conductive medium capable of contacting mammalian skin comprises the conductive adhesive compositions described herein.

Referring now to the drawings, Figures 1 and 2 illustrate an electrode 10 with a removable strip 12. Electrode 10 may be, for example, a disposable diagnostic electrocardiogram electrode (ECG or EKG) or a pacing electrode transcutaneous electrical nerve (ENET). Electrode 10 includes a biocompatible conductive adhesive field 14, as described above, which serves to contact mammalian skin following the removal of the protective removable strip 12. The adhesive field 14 holds electrode 10 to the patient's skin while While conducting electricity through it for therapeutic, diagnostic or monitoring purposes, Conductive adhesive field 14 includes the first and second main surfaces. The electrode 10 includes a means for electrical communication comprising a conductive member 16 provided with a conductive interface portion 18 in contact with a first main surface of the cortductive adhesive field 14 and a flap portion 20 extending beyond the conductive adhesive field. 14 for mechanical and electrical contact with electrical instrumentation (not shown), such as by means of an alligator clip or the like. Side 22 of conductive element 16 includes a conductive layer 26 coated thereon and contacts the first surface. conductive adhesive field main surface 14. The second main surface of the conductive adhesive field 14 adheres electrode 10 to the skin following removal of the removable strip 12.

In some embodiments, the conductive member 16 may comprise a strip of polymeric material, such as a polyester film. The conductive element 16 may have a thickness in the range of about 0.05 mm to about 0.2 mm, and a conductive layer 26 coated on the side 22. The conductive layer 26 may comprise silver / silver chloride in a thickness dry coating from about 2.5 micrometers to about 12 micrometers. In some embodiments, the coating thickness is about 5 micrometers. Suitable polyester films for use as a conductive element 16 include those commercially available under the tradename SCOTCHPAK from 3M Company of Sf. Paul, Minnesota, USA, as well as those available under the designation MELINEX 505-300, 329 or 339 film from ICI Americas of Hopewell, Virginia, USA and coated with a silver / silver chloride base paint commercially available under the designation. "R-300" from Ercon, Inc. of Waltham, Massachusetts, USA.

[083] The conductive element 16 for an ENET electrode may consist of a non-woven fiber web. Such a mat comprises polyester / cellulose fibers, such as those commercially available under the tradename MANNIWEB from Lydall, Inc. of Troy, NY, USA and having a conductive layer 26 of charcoal paint commercially available under the tradename "SS24363" from the Acheson Colloids Company of Fort Huron, Michigan, USA. In order to enhance the mechanical contact between an electrode clip (not shown) and the conductive member 16, an adhesive coated polyethylene tape may be applied to the flap portion 20 on the outermost side of the conductive member 16 (e.g. opposite side 22). A surgical tape commercially available from 3M Company under the name BIENDERM may be employed for this purpose.

In some embodiments, the conductive member 16 may be presented in a multilayer construction comprising a non-conductive flexible polymeric film having a sulfur reactive surface, a metallic layer deposited on the sulfur reactive surface, and interacting therewith, and an optional metal halide layer as described in US Patent No. 5,506,059, the full disclosure thereof is hereby incorporated by reference. The conductive interface portion 18 of the conductive element 16 comprises a metal layer deposited on a sulfur-reactive surface at least on the substrate side of the polymeric film facing conductive adhesive field 14.

In other embodiments, the conductive member 16 may be a multilayer construction comprising a flexible non-conductive polymeric film, an electrically conductive layer and a thin conformable depolymerization layer of inorganic oxide (e.g. manganese dioxide) . Alternatively, the conductive element 16 may be a multilayer construction of the film with the electrically conductive layer and the depolymerization layer mutually joined. Both of the aforementioned embodiments may be constructed in accordance with the teachings of U.S. Patent No. 5,505,200, the full disclosure thereof being incorporated herein by reference. The conductive interface portion of the conductive member 16 comprises an electrically conductive layer coated at least on the side of the polymeric film facing the conductive adhesive field 14 and the thin depolarization layer coated on the electrically conductive layer and in contact with. field 14.

Some non-limiting examples of biomedical electrodes that may use the conductive ASPs of the present invention include electrodes disclosed in US Patent Nos. 4,524,087, 4,539,996, 4,554,924, 4,848,353, 4,846,185, 4,771. 713, 4,715,382, 5,012,810 and 5,133,356, the full descriptions thereof are incorporated herein by reference.

In some embodiments, the means for electrical communication may comprise an electrically conductive tab extending from the periphery of the biomedical electrodes, as seen in US Patent No. 4,848,353, or may consist of a conductive element extending. through a slot or seam in an insulating backing layer element, as seen in US Patent No. 5,012,810. Otherwise, the means for electrical communication may consist of an eyelet or other pushbutton-type connector, as disclosed in U.S. Patent No. 4,846,185. In addition, the electrical communication means may consist of a lead wire, as observed in US Patent No. 4,771,783, Regardless of the type of electrical communication media employed, a polymerized ASP of the present invention containing an electrolyte may be used. reside as a conductive adhesive field over a biomedical electrode for diagnostic (including monitoring), therapeutic or electrosurgical purposes.

[088] Another type of diagnostic procedure, which may employ a biomedical electrode of the present invention, is long-term monitoring of the electrical wave patterns of a patient's heart that serves to detect abnormality patterns. A preferred biomedical electrode structure U.S. Patent No. 5,012,810 (Strand et al.), the full disclosure thereof is incorporated herein by reference. The polymerized ASP of the present invention may be used as the ionically conductive medium in any of the embodiments shown herein. . In some embodiments, the polymerized ASP of the present invention is used as the conductive adhesive field in a biomedical electrode according to the embodiment shown, for example, in Figures 2, 3 and 4 of US Patent No. 5,012,810, [089]. Referring to Figures 3 and 4 of the present invention, another embodiment of a biomedical electrode is presented in the form of electrode 40 including an insulating construction 41, and a conductive element 42. An insulating construction 41 has a first section 44 and a second section 45 which together define opposite sides 46 and 47 of Insulating construction 41. As noted in Figure 3, each section 44 and 45 includes an elongate edge portion 50 and 51 respectively. Each of the edge portions 50 and 51 includes a boundary portion 52 and 53 respectively comprising a peripheral portion of each section 44 and 45 respectively extending along the edges 50 and 51 respectively. In this way, sections 44 and 45 are oriented to extend substantially parallel to each other, with edge portions 50 and 51 overlapping each other such that boundary portions 52 and 53 overlap one another. A seam 60 is created between edge portions 50 and 51. For use in the present invention, the term "substantially parallel" does not mean that sections 44 and 45 are precisely parallel. They may fall outside precise coplanar alignment, for example. , due to the thickness of the conductive element 42.

The conductive element 42 is substantially similar to the biomedical electrical conductor 16 described above, provided with a flap portion 61 corresponding to the flap portion 20 described above and a cushion portion 62 corresponding to the conductive interface portion 18 described above. The biomedical electrical conductor element 16 and similar conductive element 42 may be of any of the embodiments set forth above. In this embodiment, the conductive member 42 is a multilayer construction of a non-conductive flexible organic polymeric substrate 63 provided with an organosulfur surface 64, a metal layer 65 adhered thereto, and optionally a metal halide layer 66, produced in accordance with US Patent Specification No. 5,506,059 described above.

Cushion portion 62 of element 42 comprises the portion of the metal film facing conductive adhesive field 70, optionally with metal halide layer 66 in contact with field 70. Because depolarization is not required for mechanical and electrical contact with electrical equipment, metal halide layer 66 need not extend to flap portion 61. Optionally, an adhesive coated polyethylene tape may be applied to flap portion 61 in the same manner as in Figures 1 and 2 for the purpose of accentuating mechanical contact.

In general, the electrode 40 is constructed such that the flap portion 61 of the conductive member 42 protrudes through the seam 60 and over a portion of the surface or side 46. As a result, as seen in Figures 3 and 4 , the cushion portion 62 of the conductive member 42 is positioned on one side 47 of the insulating construction 41, and the flap portion 61 of the conductive element 42 is positioned on an opposite side 46 of the insulating construction 41. It will be understood that except where the portion tab 61 extends through the seam 60, the seam may be sealed by means of an adhesive or the like.

[093] As seen in Figure 4, the bottom surface 68 of flap portion 61 is shown adhered in position to section 45 by means of a double-sided tape 69. That is, the adhesion in Figure 1 between the portion of flap 61 and section 45 occur through adhesive 69 below flap portion 61 rather than on top as shown in Figure 4.

At the electrode 40 of Figure 4, a conductive adhesive field 70 comprises an ASP according to the present invention which is generally positioned below the conductive member 42. Optionally, the conductive adhesive field 70 will be surrounded by an adhesive field. of biocompatible skin 71 applied to the insulating construction 41 on the side with a cushion portion 62 over it. In some embodiments, conductive adhesive 70 may comprise hydrophobic bulk properties. In such cases, field 71 may be deleted. In some embodiments, the biocompatible skin adhesive field 71 may comprise a nonconductive polymerized ASP similar to the conductive adhesives described herein, but without the organic chloride electrolyte. Removable strip 75 is positioned against the side of electrode 40 which also includes optional skin adhesive 71, conductive adhesive 70 and cushion portion 62. Spacer 76 is positioned between removable strip 75 and a portion of the construction insulator 41 for easy separation.

[095] Any variety of removable strip materials (eg, removable strips 12, 75) can be used on the aforementioned electrodes. Such a removable strip, for example, comprises a polymer (e.g., a polyester or polypropylene material) coated with a removable-type silicone coating to make the strip readily separable from skin adhesive and conductive adhesive. In some embodiments, a strip comprising a polymer, such as a polyester or polypropylene material, coated with a fluorochemical layer is useful and readily separable from the skin adhesive and the conductive adhesive. Removable strips suitable for use on the aforementioned electrodes may include removable fluorochemical coatings in accordance with the descriptions of US patent pending serial numbers 11 / 027,612 (filed December 28, 2004), 11 / 027,605 (filed December 28, 2004). December 2004), 11 / 027,633 (filed December 28, 2004), 11 / 027,606 (filed December 28, 2004) and 11 / 027,604 (filed December 28, 2004). Suitable commercially available fluorochemical polyester strips are available from 3M Company of St Paul, Minnesota, USA under the tradename SCOTCHPAK 1020 SCOTCHPAK 1022, SCOTCHPAK 9741.

[096] Regardless of sections 44 and 45 of insulating construction 41, a relatively thin rigid flexible material is typically used to provide the electrode in a construction that is comfortable to the user. In some embodiments, the material may be a foamed polymer, for example a polyethylene foam. Other suitable materials include nonwoven pads (e.g., polyester nonwoven pads), paper and clear films. Some non-limiting examples of transparent films include a polyester film, such as those commercially available under the tradename MELINEX from DuPont / Teijin Films, Hopewell, VA, USA. 0.05 mm thick and a commercially available surgical tape from 3M Company as the TRANSPORE non-embossed tape. In some embodiments, the materials comprise non-woven pads made from high speed hot air block extruded polyurethane fibers which exhibit exceptional flexibility, elasticity and breathability. Suitable non-polyurethane materials produced by suitable high speed hot air block extrusion which can be used in the electrode insulating construction 41 according to the present invention are generally described in European Patent Publication No. 0 341 875 (Meyer) and the corresponding US Patent No. 5,230,701 (Meyer et al.), The full descriptions thereof are incorporated herein by reference.

[097] Optionally, the insulating construction may include a skin adhesive on its surface in contact with the remainder of the electrode 40.

[098] In embodiments of the invention, the batt materials (high speed hot air block extruded polyurethanes produced) used in the insulating construction 41 may have a batt base weight of from about 60 to about 140 g / m2 (e.g. about 120 g / m2). These materials will also have adequate tensile strength and moisture vapor transmission rate. Suitable moisture vapor transmission rates include those in the range of about 500 to about 3000 grams water / m2 / 24 hours, and in some embodiments from about 500 to about 1500 grams water / m2 / 24 hours. when tested in accordance with ASTM E96-80 at 21 Xi and 50% relative humidity. In some embodiments, the material has a degree of elasticity of at least about 85% in all directions after a 50% stretch.

Although the insulating construction described herein can be made to have a variety of dimensions and can be made in virtually any size or shape, it will be appreciated that conventional biomedical electrodes are relatively small devices. In the electrode embodiments described herein, the dimensions of the insulating construction will typically range from about 3.5 to about 4.5 cm in a first dimension (e.g., width) and from about 5.5 cm to about 10 cm in a second dimension (eg length). Depending on the materials used, a thickness of about 200 to 600 micrometers typically provides adequate strength and a low relief or profile suitable for most applications.

Regardless of adhesive 69, any of the double-sided acrylate ester adhesives may be used. In some embodiments, adhesive 69 may be the same adhesive as described herein for the skin adhesive, but with an inherent viscosity of about 1.3 to about 1.45 dL / g. For the field 70 of the conductive adhesive, conductive adhesives, such as those described above useful for conductive medium 14, are preferred.

[0101] It will be appreciated that the dimensions of the various layers, and their conformation during association, should not be sized in any of the various Figures. Indeed, the features may be shown in the Figures somewhat exaggeratedly in order to better illustrate the features of the building (s) shown and thereby facilitating a better understanding of the building. In general, a substantially flat appearance as a whole with only a very small "s" type curve in the conductive member 42 is accommodated by the arrangement despite the multilayer construction of the member 42.

Other examples of biomedical electrodes that may use the conductive ASPs of the present invention include the electrodes disclosed in US Patent Nos. 4,527,087, 4,539,996, 4,554,924, 4,848,353 (Engel), 4,846,185 (Carim). ), 4,771,713 (Roberts), 4,715,382 (Strand), 5,133,356 (Bryan et al.), The full descriptions thereof are incorporated herein by reference. The methods of preparation of such electrodes are set forth in these patents, except that the polymerized ASPs of the invention may be substituted for the field of conductive adhesive and optionally also for the field of skin adhesive provided in these patents.

Examples [0103] The embodiments of the invention are further illustrated by the following non-limiting examples, where all parts are by weight unless otherwise indicated. Test Methods [0104] For testing purposes, the electrode pairs have been adhered to each other, and their bicontinuous adhesive layers are placed face-to-face. This provision is specified in a standard published by the American Association for Medical Instrument Advancement (AAMI) for determining proper performance for a biomedical electrode used in ECG Disposable Electrodes, specifically the American National Standard for Advancement of Medical Instruments (1984), the description of this incorporated herein by reference, for testing methods and conditions for minimum standards, DC Impedance (less than 100 mV), AC Impedance (Z1D, less than 2 kOhms), Defibrillation Overload Recovery (SDR) after 4 pulses, less than 100 mV, 5 seconds after 4 capacitor discharges) and a bias potential change rate. Residual strength (SDR slope, not greater than 1 mV / sec) was measured for Test Examples and Comparative Examples according to these standard test methods.

Example 1 [0105] This example employs an organic chloride electrolyte in a conductive adhesive used on flap-type electrodes. A microemulsion was prepared for use as a conductive adhesive according to the invention. Micromemulsion was prepared in the manner generally described in co-designated U.S. Patent No. 6,709,716 issued March 23, 2004 by Uy et al. More specifically, a first mixture was formed by mixing amounts of two monomers, namely 14 grams of acrylic acid as the hydrophilic monomer with 14 grams of isooctyl acrylate as the hydrophobic monomer that was obtained commercially, for example. from Atofina Chemicals, Inc. of Philadelphia, PA, USA. To this mixture were added 7 grams of a surfactant, commercially available under the tradename BRIJ 98 from Uniqema of New Castle, DE, USA, and 3 grams of a surfactant commercially available under the tradename HETOXOL OL35 from Global Seven of Franklin, NJ, USA. Then 0.3 grams of the commercially available photoinitiator under the tradename IRGACURE 2959 was added to Giba Gigy Corp. to complete a first blend.

A second mixture was then prepared by mixing 22 grams of water, 8 grams of choline chloride available from Spectrum Chemicals of Brunswick, NJ, USA, 10 grams of glycerol and 25 grams of glycol butylene, both available. from Sigma Chemicals of Milwaukee, WI, USA.

The first and second mixtures were combined together to form a microemulsion. To the microemulsion, 0.2 grams of a hydrophobically modified polyacrylate prepared from an acrylic acid monomer, commercially available under the tradename PEMULEN TR-2, obtained from Noveon Inc. of Cleveland, OH, USA, was added as a viscosity modifier and 0.2 grams of polyethylene glycol diacrylate (400) obtained from Sartomer Company, Inc. of Exton, PA, USA were added as a crosslinking agent. After addition, the microemulsion remained clear and stable, and the viscosity increased to approximately 0.2 Pa.s (200 cp), readily processable using conventional techniques.

The thickened microemulsion was then coated using a knife coating application device over a removable strip as the substrate. The knives were adjusted such that a 0.64 mm (25 mil) thick coating was obtained. Polymerization in the coated microemulsion was stimulated by exposure to ultraviolet radiation using a Black Light 350 commercially available from Sylvania of Danvers, MA, USA. A total dose of 1800 mJ / cm2 was applied for approximately 7 minutes, forming a bicontinuous conductive adhesive. This conductive adhesive showed excellent adhesion to human skin.

Several 1.0 cm square samples of this adhesive were attached to the silver / chloride-based conductive paint backing layer on one side and to a removable strip on the other side. The backing layer was larger than the adhesive sample (2 cm x 1 cm) leaving 1 square centimeter as a tab for electrical contact. The backing layer was made by coating a commercially available silver chloride / silver chloride-based conductive tapeworm solution under the tradename "R300" from Ercon Inc. of Waltham, MA, USA on a polymer backing layer made of from a 0.1 mm thick polyester film commercially available under the tradename MELINEX 505 from ICI Films of Hopewell, VA, USA using a yarn coating procedure. The paint had a solids content of 58%, which comprises 70% elemental silver. The carrier solvent for the paint was methyl propyl ketone (MPK). The coated film was then dried at room temperature for 5 minutes followed by drying at 93 ° C (200 ° F) for 5 minutes.

Comparative Example C1 (0110] A microemulsion adhesive was prepared according to the procedure described in Example 1 above, with the following changes: Four grams of potassium chloride in place of choline chloride were used. water, and the surfactant mixture was replaced by 10 grams of BRIJ 97 obtained from Uniqema of New Castle, DE, USA, Example 1 and Comparative Example Cl [0111] Six flap-type electrodes were fabricated from the adhesives described in Example 1 and Comparative Example C1 Three of the electrode pairs were placed in a 15% relative humidity chamber for 18 hours with the adhesive surface exposed, while three other pairs were not exposed to 15% relative humidity. electrode were prepared from both the unexposed sample and the 15% relative humidity sample, which were adhered to each other and their bicont adhesive layers (bare located in face-to-face contact in accordance with the AAMI standard. Each result in Table 1 shows the average 3-pair test results for Example 1 and Comparative Example G1, before and after 15% relative humidity exposure, Table 1 [0112] After balancing the adhesive to a relative humidity of 15%. %, the electrodes of Example 1 are still electrically viable. The impedance of Comparative Example C1B increased by a factor of 50 as opposed to the electrode of Example 1B (choline chloride), where the impedance after drying increased only by a factor of 10. In addition, the C1B electrodes with potassium, failed the SDR tilt test.

Example 2 [0113] This Example employs organic chloride electrolytes in conductive adhesives used on push-button electrodes that are used for long-term monitoring and wear. The conductive element has a much smaller projection zone than flap-type electrodes. The construction of the electrode is described in detail in U.S. Patent No. 6,709,716 issued March 23, 2004 by Uy et al. Briefly, the biomedical electrode has a non-conductive backing layer provided with a push-button lined opening through which a pin or eyelet protrudes. The push button is attached to the eyelet to provide an electrical connection point for electrical instrumentation. The eyelet coating and backing layer consist of a field of the polymerized microemulsion ASP of the present invention. A removable strip protects the ASP field before use. The backing layer may be made from the same or similar materials as the insulating construction. The eyelet may be a metal-plated plastic eyelet (such as a commercially available ABS silver-chlorinated plastic veneer eyelet from Micron Products of Fitchburg, MA, USA). The pushbutton may be a metal pushbutton (such as No. 304 stainless steel eyelet commercially available from Eyelets for Industry of Thomason, CN, USA). In this type of electrode the polymerized microemulsion ASP of the present invention can serve as both a biocompatible skin adhesive and an inonically conductive medium on the electrode.

The same adhesive as described in Example 1 was used to prepare pushbutton type electrodes. As in Example 1, half of the electrodes were removed from the strip and placed in a chamber at 15% relative humidity for 18 hours with the adhesive surface exposed for rapid equilibrium with the chamber. Electrical test results according to the AAMI procedure in both electrode configurations are shown in Table 2. Each test result represents an average of 3 electrode pairs.

Comparative Example C2 Comparative Example C2 used the same push button type electrode construction as Example 2 except that the choline chloride electrolyte was replaced by potassium chloride as a Comparative Example C1. AAMI electrical test data are shown in Table 2. Each test result represents an average of 3 electrode pairs.

Table 2 The electrolytes of Example 2B exhibited a six-fold increase in impedance. None of the electrode characteristics were compromised. Comparative Example C2 electrodes failed the impedance test when exposed to a low humidity chamber.

Example 3 Example 3 employed organic electrolytes in conductive adhesives for push-button type electrodes converted to removable strips where the perimeter of the adhesive (sandwiched between the electrode backing layer and the removable strip) was exposed to a low humidity. Pushbutton-type electrode backing layers were fabricated as in Example 2 and were converted to removable strips using the adhesive synthesized in Example 1. The initial simultaneous electrical test was conducted according to the AAMI procedure using 12 electrode pairs. . The electrodes of Example 3 on the removable strip were then aged 21 21 ° (70 ° F) in two independent chambers maintained at a relative humidity of 0% and 15% for 30 days. Samples were taken from the chambers after 10, 20 and 30 days of aging. Simultaneous electrical testing on both electrode configurations was conducted according to the AAMI procedure on 12 electrode pairs at each of these time points. Average results for both electrode configurations of Example 3 are shown below in Table 3A.

Comparative Example C3 A microemulsion was prepared as follows. A first mixture was formed by mixing two hydrophilic monomers, 14 grams of acrylic acid with 14 grams of polyoxyethylene acrylate, commercially available as ester AM 90G from Shin-Nakamura Chemical Co., Ltd. of Wakayama, Japan. 14 grams of isooctyl acrylate was added as a hydrophobic monomer. To this second mixture was added 18 grams of a BRIJ 97 surfactant available from ICI to form a third mixture. Then 0.5 grams of IRGACURE 2959 initiator was added to form a fourth mixture. An aqueous mixture was then prepared containing 23 grams of water, 1.2 grams of KCl and 10 grams of propylene glycol. The aqueous mixture and the fourth mixture were combined together to form a microemulsion. To the microemulsion was added a 17% aqueous polyacrylic acid solution with a molecular weight of approximately 550,000 prepared from the monomer using standard synthetic techniques. Specifically, the polymerization was initiated by potassium persulfate from the thermo-activated initiator, and the reaction was administered under a nitrogen atmosphere at 76 ° C.

When the solution was added to the microemulsion, the microemulsion remained clear and stable and the viscosity increased to approximately 0.2 Pa.s (200 cps), readily processable using conventional techniques. The thickened microemulsion was then coated using a knife coating application device over a removable strip as the substrate. The knives were adjusted such that a 0.64 mm (25 mil) thick coating was obtained. Polymerization in the coated microemulsion was stimulated by exposure to ultraviolet radiation using a commercially available Black Light 350 from Sylvania of Danvers, MA, USA. A total dose of 1800 mJ / cm2 was applied for approximately 7 minutes, forming a bicontinuous conductive adhesive. This conductive adhesive showed excellent adhesion to human skin.

[0120] Pushbutton electrode backing layers were fabricated as in Example 2 and converted to removable strips using this adhesive. The initial simultaneous electrical test was conducted according to the AAMI procedure using 12 electrode pairs. The electrodes on the removable strip were then aged at 21 ° C (70 ° F) in two independent chambers maintained at a relative humidity of 0% and 15% for 30 days. Samples were taken from the chambers after 10, 20 and 30 days of aging. Simultaneous electrical testing on both electrode configurations was conducted according to the AAMI procedure on 12 electrode pairs at each of these time points. Average results for both electrode configurations of Comparative Example C3 are shown below in Table 3B.

Table 3A

Table 3Β * Several electrode pairs exhibited a DCO (D.C. offset) greater than 2 V within 2 seconds of the SDR (Simulated Defibrillation Recovery) pulse Example 4;

Example 4 shows the clinical performance of electrodes made from choline chloride-containing adhesives and aged for 30 days on the strip at a relative humidity of 0% and 15%. Clinical performance was measured for the time required to obtain an ECG signal after electrode application to the skin.

[0122] Materials: Pushbutton-type electrodes were manufactured from coating, adhesive, and strip materials described in Example 3. One-third of the electrodes were sealed in water-tight containment bags, these electrodes served as controls. Another third was aged on the strip at 21 ° C (70 ° F) and 0% relative humidity for thirty days and the remaining third was aged on the strip at 21 Ό (7011) and 15% relative humidity for thirty days.

The initial impedance was first measured using each electrode of Example 4 applied to an individual's arm. A sample of each electrode from Example 4 (4A, control 4B, stored @ 15% relative humidity and 4C, stored @ 0% relative humidity) was applied to each of the 4 quadrants on each torso of 12 subjects. The acceptable ECG signal has been recorded. Note that an acceptable signal was required on both threads 1 and 2. The average impedance and time results (n = 48) for the acceptable signal for each electrode of Example 4 under each condition are shown in Table 4, Table 4 Example 5 This Example employed a different organic "ion" electrolyte in conductive adhesives used on push-button electrodes. The electrode construction is identical to the construction described in Example 2 with the exception of the adhesive. The adhesive was an acrylate based single phase ASP. The adhesive precursor comprises 15 grams of acrylic acid, 20 grams of 2-hydroxy ethyl methacrylate obtained from San Esters Corporation of New York, NY, USA, 11 grams of commercially available tetrakis phosphonium chloride (methyl hydroxy) from Sigma-Aldrich of St. Louis, MO, USA, 25 grams of 1,3-butylene glycol, 10 grams of glycerol, 19 grams of water 0.55 grams of IRGACURE 2959 and 0.15 grams of polyethylene glycol diacrylate (400 ). The precursor was coated using a club coating device on a removable strip as a substrate. The knives were adjusted such that a 0.64 mm (25 mil) thick coating was obtained. Polymerization in the coated microemulsion was stimulated by exposure to ultraviolet radiation using a Black Light 350 commercially available from Sylvania of Dawn, MA, USA. A total dose of 1800 mJ / cm2 was applied for approximately 7 minutes, forming a bicontinuous conductive adhesive. This conductive adhesive showed excellent adhesion to human skin.

[0125] Pushbutton-type electrode support layers were fabricated as in Example 2 and converted to removable strips using this adhesive.

Comparative Examples C5 Comparative Example C5 used the same electrode construction as Example 4 except for the replacement of the phosphonium chloride adhesive with a potassium chloride adhesive of the same composition with the following exceptions: 11 grams of phosphonium chloride were replaced by 4.2 grams of potassium chloride and 19 grams of water were increased to 25.8 grams.

Example 5 and Comparative Example C5 Electrical testing according to the AAMI procedure was conducted on both electrode configurations (3 each) for Example 5 and Comparative Example C5. As in the previous examples, half of the electrodes were removed from the strip and placed in a 15% relative humidity chamber for 18 hours with the adhesive surface exposed for rapid equilibrium with the chamber, while the other half was not exposed to moisture condition. 15%. Results are shown in Table 5, below.

Tables [0128] Example 5B electrodes with phosphonium chloride resist drying with a six-fold increase in impedance. None of the electrode characteristics were compromised. Comparative Example C5B, potassium chloride-based electrodes, showed a 20-fold increase in impedance and failed the impedance test when exposed to a low humidity chamber.

Although embodiments of the invention have been described in detail, changes and modifications to the embodiments described should be apparent to those skilled in the art. Such changes and modifications are contemplated in the character and scope of the invention as set forth in the appended claims.

Claims

Claims (9)

1. CONDUCTIVE ADHESIVE COMPOSITION, characterized by the fact that it comprises: (a) pressure sensitive adhesives; (b) 0.5 to 10 parts by weight of electrolytes comprising water-soluble or water-dispersible organic chlorides; and (c) humectants, wherein the electrolytes and humectants are at least sparingly miscible with each other. CONDUCTIVE ADHESIVE COMPOSITION according to claim 1, characterized in that the pressure sensitive adhesive is a bicontinuous composition comprising an aqueous phase and an oil phase. The conductive adhesive composition according to claim 2, wherein the bicontinuous composition is derived from a polymerizable microemulsion composition, wherein the microemulsion composition comprises: (a) an aqueous phase comprising one or more monomers or hydrophilic oligomers and / or one or more water amphiphilic monomers or oligomers, water-soluble or water-dispersible organic chloride, surfactants and humectants; (b) an oil phase comprising one or more hydrophobic monomers or oligomers. Conductive adhesive composition according to Claim 1, characterized in that the organic chloride comprises an onium chloride selected from the group consisting of quaternary ammonium chloride, phosphonium chloride, oxonium chloride, sulfonium chloride or mixtures of two. or more of the aforementioned compounds. CONDUCTIVE ADHESIVE COMPOSITION according to claim 3, characterized in that the hydrophilic monomers and oligomers comprise free and ethylenically unsaturated free (co) polymerizable polar species, CONDUCTIVE ADHESIVE COMPOSITION according to claim 3, characterized in that the hydrophilic or amphiphilic oligomers comprise free-radical and ethylenically unsaturated polar (co) polymerizable species which have low solubility in the oil phase or are both water-soluble. soluble in oil. CONDUCTIVE ADHESIVE COMPOSITION according to claim 1, characterized in that the humectant has the following formula: M0 (CH2 CH20) m H where M is selected from the group consisting of hydrogen and C1 -C6 alkyl; and is an integer from 1 to 25. 8. BIOMEDICAL ELECTRODE, characterized by the fact that it comprises: (a) a conducting element; and (b) the conductive adhesive composition as described in one of claims 1 to 7. Biomedical electrode according to Claim 8, characterized in that the conductive element comprises a backing layer and a conductive component associated with the backing layer, the conductive adhesive composition comprising a first and a second main surface being that the first major surface of the conductive adhesive is operatively associated with the conductive component so that electric current can pass through the conductive adhesive to the conductive component or through the conductive component to the conductive adhesive.