EP0128919A1 - Composition polymere fa onnable - Google Patents

Composition polymere fa onnable

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Publication number
EP0128919A1
EP0128919A1 EP84900090A EP84900090A EP0128919A1 EP 0128919 A1 EP0128919 A1 EP 0128919A1 EP 84900090 A EP84900090 A EP 84900090A EP 84900090 A EP84900090 A EP 84900090A EP 0128919 A1 EP0128919 A1 EP 0128919A1
Authority
EP
European Patent Office
Prior art keywords
composition according
composition
electrically
conductive
contact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP84900090A
Other languages
German (de)
English (en)
Inventor
John William Kennedy
Malgorzata Teresa Mandziuk Kennedy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0128919A1 publication Critical patent/EP0128919A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/02—Details
    • A61N1/04—Electrodes
    • A61N1/0404—Electrodes for external use
    • A61N1/0472—Structure-related aspects
    • A61N1/0492—Patch electrodes
    • A61N1/0496—Patch electrodes characterised by using specific chemical compositions, e.g. hydrogel compositions, adhesives
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25—Bioelectric electrodes therefor
    • A61B5/251—Means for maintaining electrode contact with the body
    • A61B5/257—Means for maintaining electrode contact with the body using adhesive means, e.g. adhesive pads or tapes
    • A61B5/259—Means for maintaining electrode contact with the body using adhesive means, e.g. adhesive pads or tapes using conductive adhesive means, e.g. gels
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/08—Metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
    • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
    • A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
    • A61B2562/0215—Silver or silver chloride containing

Definitions

  • the present invention relates to a formable polymer composition, in particular a composition which has electrically-conductive properties, those properties being retained even after forming.
  • a formable polymer composition in particular a composition which has electrically-conductive properties, those properties being retained even after forming.
  • an electrically-conductive polymeric material which is formable might find ready application. This is especially true in the medical field where an electrically-conductive formable polymeric material which is also contact-adhesive to the human skin would find many applications. For example, such a material would find application in the production of electrocardialogical monitoring transducers and cardiac stimulation devices, both commonly known as "electrodes”.
  • a formable polymer composition which composition comprises a formable polymeric material having dispersed therein an electrically-conductive material in particulate form comprising metal or metal-coated particles, the conductive material being present in an amount to provide an overall specific conductivity in the composition of at least about 2 mho cm -1 .
  • a wide range of formable polymeric materials can be formulated with an electrically-conductive material comprising metal or metal-coated substrate particles and in an amount to provide an overall specific conductivity in the composition which makes it truly electricallyconductive, while at the same time remaining formable.
  • compositions can be formulated in which a formable polymeric base material retains a significant and meaningful proportion of its processing characteristics, so as to make the compositions formable in various ways, for example, by moulding, extrusion or other shaping techniques, while at the same time affording true electrical conductivity.
  • the electrically-conductive material in particulate form may comprise a metal as such, for example, lead, copper, iron, steel, platinum, gold or silver.
  • the electrically-conductive material may comprise substrate particles coated with a film of metal.
  • metal or metal-coated particles are randomly dispersed throughout a non-conductive formable polymeric matrix in a proportion which exceeds that of the critical percolation volume indicated by percolation theory as it applies to the unstructured case of non-interpenetrating bodies of specified shape and size distribution. In excess of this critical percolation proportion, it is inevitable that a sufficient number of the conducting particles are in contact with each other so as to provide random conducting pathways throughout the polymeric material, no matter what shape ultimately it is made to adopt.
  • nonconducting substrate particles bearing a thin coating or film of a metal In the case of medical devices placed in contact with the skin, they preferably include a metallic conductor which is non-corroding, non-corrosive, non-toxic and which neither exhibits nor affords any adverse side effects when placed in close contact with the human skin for extended periods of time.
  • metallic silver is a preferred conductive material and in the case of silver the cost reduction obtained by depositing a thin coating of silver on a suitable substrate is substantial.
  • the requirements of the present invention for low current applications maybe met by providing a substrate which comprises small glass spheres (ballotini) which are available in medically approved grades.
  • the spheres can easily be coated with a thin layer of silver, typically a film having a thickness of about a few Angstrom units, by the well known chemical reduction process using a silver salt, for example, silver nitrate and invert sugar. This is the basis of the "silver mirror" test used in classical chemical analysis.
  • the spheres may be of metal-coated e.g. silver-coated, plastics material.
  • the conductive material must be present in the formable plastics composition of the invention in an amount to provide an overall specific conductivity of at least about 2 mho cm -1 .
  • the conductive material is present in an amount to provide an overall specific conductivity of from about 10 mho cm to about 100 mho cm -1 .
  • the proportion of electrically-conductive particles in the overall polymeric matrix necessary to achieve the above-mentioned levels of overall specific conductivity is highly dependent on the shape and distribution of shapes of the particles and on their size distribution. However, expressed on a volume basis that proportion for any given shape and distribution is essentially independent of the kind of conductive material employed, i.e. which metal is used, and whether or not metal particles or metal-coated particles are employed.
  • spheres of narrow diameter distribution preferably silver-coated glass spheres
  • they may typically be present in an amount in excess of about 35% by volume of the total volume of the composition to provide the necessary conductivity, with an upper limit of about 68% by volume for randomly packed spheres after shaking to maximise packing or about 74% by volume for spheres that are "close-packed", i.e. packed in the most efficient and regular manner.
  • the upper limit to avoid excessive loss of polymer properties will be about 60% by volume, preferably about 55% by volume.
  • the particulate form chosen need not be spherical.
  • silver-coated glass spheres or steel spheres are particularly useful in the preparation of formable contact adhesive compositions as described below, the incorporation of spherical particles can adversely affect the tensile properties of polymeric materials.
  • the particulate form chosen preferably will be an elongate form with a high length to diameter ratio such as rods or fibres.
  • percolation theory is sufficiently advanced for randomly oriented cylinders of uniform length and a high length to diameter ratio, i.e. rods, to provide accurate predictions from theory of the levels of rod-like or fibre particles necessary to achieve the above-stated specific conductivity.
  • the polymeric material of the formable composition of the invention may be selected from a wide variety of formable polymeric materials.
  • the polymeric material may be a thermoplastics material or a thermoor cold-setting material, of which preferred thermoplastics materials are, for example, polyvinyl compounds, e.g. polyvinylchlorides; polyalkenes, e.g. polyethylenes, polypropylenes and polyisobutenes; polyacrylates; polymethacrylates; and polyamides e.g. nylon, and of which preferred thermo- or cold-setting materials are, for example, epoxy resins and silicones e.g. silicone rubbers.
  • the composition of the invention preferably includes one or more components which provide a composition having contact- or pressure-sensitive adhesive properties.
  • the components of the composition should be selected so as to provide a hypoallergenic composition, especially in the case of any application where the composition may remain in contact with the skin for a long period of time.
  • a preferred composition for use in applications involving contact with the human skin is based on a polyisobutene mixed with one or more phase structure, flow and/or moisture permeability modifiers, for example, low molecular weight polyalkenes, e.g. polyethylene, or hydroxyalkyl celluloses, e.g. hydroxymethyIcellulose.
  • the polyisobutene typically has a viscosity average molecular weight in the range of from about 40,000 to about 100,000.
  • the invention also includes an electricallyconductive device for medical purposes, which device comprises one or more formed portions of a composition in accordance with the invention, if desired supported on a substrate structure.
  • the device of the invention is a transducer suitable for use in electrocardialogical applications in place of the so-called "electrodes" of the prior art.
  • the substrate structure comprises a backing member through which is mounted an electrically-conductive contact whereby an electrical lead can be connected to one part of the contact at the rear of the backing member and the contact provides an unbroken electrical path through the backing member to a portion of an electricallyconductive adhesive composition in accordance with the invention forming at least part of an adhesive layer disposed on the front of the backing member whereby the front of the transducer may be adhered to the skin.
  • the electrically-conductive contact is a stud compatible with existing e.c.g. leads which provides a means of connecting the leads to the transducer.
  • a stud may be formed of metal or of a formable composition in accordance with the invention which can provide a suitably formed rigid stud e.g. a composition based on nylon or polypropylene.
  • the contact is mounted at or about the centre of the backing member and, in order to avoid uncomfortable corners, the backing member is preferably a disc. With such a disc the front surface of the backing member preferably bears an annulus of non-conducting contact adhesive material surrounding a central portion or plug of said electrically-conductive adhesive composition.
  • the annulus is formed of a hypoallergenic pressure-sensitive skin adhesive material, for example. a foamed layer having an adhesive coating e.g. of an acrylic composition, on its upper and lower faces, such as has been found suitable for ostomy applications.
  • a foamed layer having an adhesive coating e.g. of an acrylic composition on its upper and lower faces, such as has been found suitable for ostomy applications.
  • the device may be a multiple contact transducer for e.c.g. applications and comprising an array of electrically-conductive portions carried on an insulating backing member, each portion being in electrical contact with an isolated terminal, and at least one portion comprising an electrically-conductive adhesive composition according to the invention.
  • the electrically ⁇ conductive portions preferably are disposed on the backing member in an arcuate array for attaching to a patient's chest around the heart.
  • the electrically ⁇ conductive portions Preferably also there are at least three electrically-conductive portions.
  • one form of transducer as first defined above can be manufactured by a method which comprises: (a) forming a sheet of a laminate comprising a layer of a conductive and adhesive composition according to the invention sandwiched between two release layers, (b) sub-dividing the laminate into transducer elements, preferably elements which are disc-shaped, (c) removing one release layer, and
  • transducers of both embodiments may be produced by a method which comprises: (i) forming a sheet of laminate comprising a layer of non-conducting contact adhesive composition, such as is presently used in ostomy, sandwiched between a release layer and a supporting layer,
  • the electrode elements are discs and the apertures are essentially round in plan. In another embodiment as described below the electrode elements are horse-shoe shaped, and preferably at least three e.g. six, apertures are provided.
  • variable conductivity characteristics can be encountered due to the electrically insulating nature of dead skin carried on the body surface. This can be avoided simply by first preparing the skin surface e.g. by lightly abrading with emery paper, or with a pumice stone or the like to remove dead skin. Such preparation, however, even though it is simple and quick may not be desirable in certain circumstances, and in any event relies on a nurse or other operative involved to carry out the preparation.
  • the composition according to the invention includes an additive to reduce contact resistance with the skin when applied to unprepared skin, that is skin from which the keratin (dead skin) layer has not been removed by abrasion or the like.
  • such an additive is one which provides an aqueous medium within the composition to provide the necessary electrical continuity through the keratin layer.
  • the composition preferably includes an additive comprising a mixture of: 1. Water, 2. A hygroscopic agent such as glycerine or glycerol, and
  • a thickening agent for example, carboxymethylcellulose, which mixture may be used in an amount of, for example, frarm about It to about 5% by weight of the total composition.
  • a first mixture comprising additive and electrically-conductive material, and a second mixture comprising polymer and electrically-conductive material, those mixtures then being blended to form the final composition.
  • a second mixture comprising polymer and electrically-conductive material, those mixtures then being blended to form the final composition.
  • preferred ranges of the various components for the first mixture are:
  • the overall composition will include no more than about 20% by weight of such a first mixture including said additive since the use of more than about 20% by weight could result in a composition that is both too soft and which could leave a heavy residual deposit on the skin when the transducer is removed after use.
  • the upper limit for the first mixture is about 15% by weight based on the total weight of the composition.
  • Example 1 A composition in accordance with the invention was formulated as follows:
  • the above electrically-conductive hypoallergenic adhesive was prepared from the above-identified components in the above amounts by mixing the coated spheres with the polymeric component in a Z-blade high shear mixer for about 20 minutes at a mixing speed of about 200 r.p.m.
  • the silver-coated glass spheres used in the above composition were prepared according to the following procedure: 1. Preparation of solutions:
  • the adhesion and strength of the silver coating depends very much on the cleaning of the sphere surfaces. It is very difficult to clean glass perfectly, and variations in the quality of the surface, type of glass etc. can give very different results. Experience shows, however, that rough cleaning of the surfaces is usually sufficient for coating.
  • Cleaning is effected by using fuming nitric acid. With this treatment any silver coating present is destroyed, and where a first coating is present the spheres should be rinsed with distilled water and again cleaned with acid.
  • the coating operation is performed at ambient temperatures using a shallow tray into which the glass spheres are placed.
  • the glass spheres used are glass ballotini of 0 to 20 microns diameter, made of soda glass, and obtained from English Glass, cheaper leaded glass being avoided for toxicological reasons. Since this grade of ballotini contains traces of ferrous metallic contamination, this is first removed by agitating a slurry of the spheres in water using a magnetic stirrer on which the traces of metallic contamination collect as a black metallic powder deposit. Removal of this contamination is necessary since the contaminant interferes to some exent with the silver coating process described below.
  • the mixture of volume V thus obtained is poured onto the layer of spheres in the tray. Then a volume of the reduction solution D equal to one-third of the volume of solution A used above is added. The reaction begins immediately, the liquid becomes cloudy and turns black, and the whole should be stirred slowly to obtain a uniform coating. After 2 minutes the tray begins to develop a metallic gleam, but it is necessary to wait for some time after that before the spheres are removed.
  • the end of the reaction is indicated by seeing the mixture become clear with dark particles floating on the surface.
  • the spheres may now be removed, rinsed first in water then in alcohol and dried as quickly as possible. The coating operation is then complete.
  • the coating is the first coating applied to the spheres, it is best to repeat the operation again after first removing the silver coating with fuming nitric acid as described for step 2 above. Experience shows that a subsequent silver coating forms a much more adherent layer than the first. Similarly, if something goes wrong or if the coating formed appears to be poor then the operation should be repeated again. It will be understood, of course, that
  • any other closely fractionated range grade of glass spheres may be used in place of the 0 - 20 micron grade, and other ranges are available from English Glass;
  • ⁇ in particular, a higher average size cut may be more advantageous in some applications, and
  • the glass sphere grade used (0 - 20 microns) is in any event necessarily subjected to further fractionation by the above processing since a slower settling fraction comprising finer particles is discarded whenever the spheres are separated from associated liquid e.g. when they are removed from the tray. This in fact improves matters insofar as a narrower distribution is effectively produced, which means a lower critical percolation volume of spheres and greater preservation of the polymer matrix properties.
  • Example 2 Another composition in accordance with the invention was formulated as follows:
  • the above electrically-conductive hypoallergenic adhesive composition was prepared by pre-mixing all of the polymer components in the above amounts in a high shear Z-blade mixer at about 100°C for about 10 minutes and then, while continuing to mix, by slowly adding the silver-coated glass spheres at a rate slow enough to avoid the paste becoming dry in appearance.
  • composition in accordance with the invention including components to promote electrical conductivity contact at the skin (keratin) interface was formulated as follows:
  • a first mixture (Mixture A) was prepared according to the formulation: Component % by weight of the total composition Glyceroi (B.P. grade, ex. BDH) 12.25
  • a second mixture (Mixture B) was also prepared according to the formulation: Component % by weight of the total composition Polyisobutene (Viscosity average molecular weight about 50,000 as used in Example 2) 25 Silver-coated glass spheres 75
  • Mixture B was then cooled to below about 50°C, and Mixture A was added slowly in small portions while
  • Figure 1 shows a cross-section through a known e.c.g. "electrode”,
  • Figure 2 shows a cross-section through one form of e.c.g. transducer in accordance with the invention
  • Figure 3 shows a cross-section through another form of e.c.g. transducer in accordance with the invention
  • Figure 4 shows a plan view from below of a multiple contact e.c.g. transducer in accordance with the invention.
  • Electrodes are almost invariably constructed using the principle of a silver/silver chloride voltaic cell to obtain maximum electrical contact with the skin at suitable monitoring locations. Universally, they take the form shown in Figure 1, in which the "electrode” structure comprises a flexible plastics disc-shaped backing member 11, typically comprising plasticised polyvinylchloride.
  • the backing member 11 has mounted thereon through its centre a metal "press stud” contact12, which includes a stud portion 13 upstanding from the rear face 14 of the backing member, that portion being connectable to a lead of an e.c.g. machine.
  • the contact 12 extends through the centre of the backing member and includes a portion 15 exposed at front face 16 of the backing member.
  • the front face 16 of the backing member carries an annulus 17 of adhesive material which in turn carries an annulus 18 of release paper protecting the adhesive annulus 17.
  • the annuli 17 and 18 surround a pad 19 of foamed plastics material which is impregnated with a silver chloride electrode gel to provide electrical contact with the skin.
  • the annulus 18 carries a cover 20 of low moisture permeability material.
  • the annulus 18 together with cover 20 is peeled away from the remainder of the "electrode” and that in turn is placed on the patient's skin with the gel-impregnated pad 19 in contact with the skin.
  • the "electrode” is held on the skin by adhesive annulus 17 and electrical connection is made via portion 13 of contact 12.
  • the electrode gel tends to dry out during storage which renders the "electrode” useless for monitoring purposes.
  • Electrodes are highly variable. They are furthermore very susceptible to patient movement which may alter the effective "cell” distance.
  • the e.c.g. "electrode” or transducer there shown again comprises a flexible plastics disc-shaped backing member 11 having mounted thereon at its centre a metal contact 12.
  • the contact includes a stud portion 13 upstanding from the rear face 14 of the backing member which is connectable to a lead of an e.c.g. machine.
  • the stud 12 extends through the centre of the backing member and into intimate contact with a layer 26 of an adhesive and conductive composition in accordance with the invention, for example, a composition as described specifically above.
  • the layer 26 in turn is covered by a release paper 18' e.g. a silicone release paper.
  • a release paper 18' e.g. a silicone release paper.
  • the layers of the transducer are coterminous and in use the release paper 18' is removed and the transducer is adhered to the skin via layer 26. That layer being conductive as well as adhesive provides the necessary electrical contact between the lead attached to stud portion 13 and the patient's skin to which layer 26 is adhered
  • FIG. 3 Another form of e.c.g. transducer in accordance with the invention is shown in Figure 3. That transducer is similar to the transd ucer of Figure 2 except that the adhesive laye r i s ca rried on a support layer 25 e .g. of nylon mesh , and layer 26 comprises an annulus 27 of non-conducti ve adhe si ve material and a central plug 28 of a conductive-adhesive composition in accordance with the invention, for example, as described speci f ically above.
  • the annulus 27 is preferably a hypoallergenic adhesive mate rial , for example, as is presently used in ostomy.
  • the transducer of the invention can be produced in a form superficially similar to the form of known "electrodes" as shown in Figure 1.
  • the electrode gel i mpregna ted foam i s replaced by a composition in accordance wi th the invention and the annulus 17 is selected to comprise a hypoallergenic adhesive material.
  • the transducer of the invention offers the added advantage of reduced noise to signal ratio by virtue of the reduced area of electrically-conductive material, which can act in the manner of an antenna.
  • composition of the invention does not "dry out” in the same manner as a silver chloride electrode gel. According ly, there is no requi rement for special packaging and transducers as shown in Figures 2 and 3 and as described above have an almost indefinite shelf life.
  • e.c.g. transducer designed as described above offers substantial improvements over e.c.g. "electrodes" currently in use. For example , based on a commercial check-list for the ideal monitoring "electrode” , a number of advantages may be noted in comparison with “electrode s" of conventional type . Thus , e .c .g . transducers in accordance with the invention: 1. Require no time or education to prepare for application to the patient:
  • the basic skin adhesive system is used by ostomates and requires only the removal of a release paper which protects the adhesive. Adhesion to skin is immediate though generally improves if pressure is sustained for a short t ime allow ing the ma te rial to warm to body temperature and then to increase contact by flow. There is no special packaging to remove , as in the case of "electrodes" using an electrode gel , where this is required to minimise evaporation which can result in drying out of the "electrode”. The amount of preparation and training is not greater than that required for present "electrodes". Our transducer does not require any checking to see that an electrode gel pad is sufficiently moist nor, as in some cases, to add electrode gel to the pad of an "electrode" supplied in the dry state.
  • Electrodes One feature of our transducers is that they can be made with a smaller area of contact with the skin than existing electrode gel "electrodes". This is because the electrical contacting medium is itself adhesive unlike the electrode gel impregnated pad. This immediately offers improvements in patient comfort. In addition, there is no "burning” or “chilling” sensation which is often experienced by patients resulting from contact with the electrode gel.
  • Our adhesive system rapidly adopts body temperature and is not cold to the touch. 7. May be removed quickly and discarded without cleaning the skin:
  • transducers combine the good qualities of the basic skin adhesive system developed for ostomates with the superior electrical characteristics of the random conducting medium described above.
  • our transducers offer a much improved stability in base line than conventional "electrodes". This results from the fact that they are not based on a voltaic cell contact with the patient with all the consequences of this, arising, for example, from variability with patient movement, perspiration etc. It is also the case that our transducers offer better electrical sensitivity (or gain) in the electrical signals that are the subject of measurement.
  • the transducer described above with reference to Figure 2 can be produced by forming, e.g. by calendering, a laminate comprising a layer of conductive adhesive composition sandwiched between two layers of release paper. That laminate can then be cut into discs and adhered, by removing one layer of release paper, to the front face of a flexible polyvinylchloride disc of the same diameter having a press stud contact fitted at its centre.
  • a laminate is formed, but this time having an adhesive layer comprising a non-conducting adhesive material, for example, as is used in ostomy, sandwiched between a release layer and a support layer, e.g. of nylon mesh. That laminate is cut into discs, and at the centre of each disc a hole is punched of a size to accommodate the plug 28 of conductive adhesive composition.
  • Each annulus thus produced is adhered via the support layer to the front face of a flexible polyvinylchloride disc of the same diameter as the original laminate disc, the polyvinylchloride disc again having a press stud type contact fitted at its centre.
  • the release paper is removed, the central hollow is filled, either by a hot or cold fill technique, with a measured quantity of a conductive adhesive composition in accordance with the invention, the structure is checked for electrical contact between the composition and the stud, and the whole is covered with a disc of release paper. Finally, the transducer is pressed, again either by a hot or cold technique, to complete its formation.
  • a metal press-stud When a metal press-stud is used, it may be necessary to pre-prepare or "prime" the surface e.g. of portion 15, which is in contact with the conductive adhesive composition, by applying a rough coating of conductive material e.g. conductive-epoxy or the like adhesive, to promote good adhesive bonding (and hence electrical contact) between the skin adhesive and the metal stud.
  • conductive material e.g. conductive-epoxy or the like adhesive
  • a suitable conductive epoxy adhesive may be prepared from a standard, commercial, two-pack epoxy comprising epoxy resin and diamine curing agent such as:
  • Bostik Bostik and these may be of either the slow set (about 12 to about 24 hours) or quick set (about 1 hour) variety.
  • the commercial product compri ses two components which are mixed together (usually in equal proport ions ) j ust prior to use . Af ter the components are mixed , the setting process begins and the material can be used only until it has set to the extent that i t is unworkable .
  • each of the two component s i n a comm e rc i al prod uct i s separate ly mixed with si lve r-coated glass spheres (prepared as described above ) , or the like; the optimum formulation being:
  • Epoxy Component about 25% by weight
  • Silver-coated glass spheres about 75% by weight, although the range of from about 70 to about 80 % by we ight of silver-coated glass spheres or the like to about 30 from about 20% by weight of epoxy component is acceptable for both of the epoxy components.
  • the epoxy component should be warmed e.g . to from about 40 to about 80 °C, to make mixing easier, and the silver spheres added slowly while gently stirring the mixture. After a period of final mixing to ensure homogeneity, the material is cooled and then checked for electrical conductivity.
  • the two conductive epoxy components can be stored indefinitely as long as they are separate.
  • the same procedure as with the commercial epoxy adhesive i s followed that is the two components are mixed in equal proportions and the mixture worked onto the stud surface before it sets sufficiently to prevent flow.
  • transducers described above with reference to Figures 2 and 3 may be used in the usual e.c.g. applications. In those applications a set of transducers is attached to various parts of the body and each is separately connected to an e.c.g. apparatus.
  • a commonly used arrangement uses three transducers arranged on the chest or limbs in a so-called Eindhoven triangle, for example, with a measuring transducer on the right arm (RA), a measuring transducer on the left arm (LA), and a measuring transducer on the left leg
  • LL LL
  • a set of three voltages is monitored i.e. between each pair of transducers using a differential amplifier, working in the 1 to 2 millivolt range at low current, the third transducer in each case providing a ground connection.
  • a fourth transducer is used connected say to the right leg (RL) to provide a separate means of grounding the patient on a common line with the measuring instrument.
  • Electrode which can be done because the whole of the face area is adhesive, better results can be obtained by constructing a device of the type illustrated in
  • Figure 4 shows a multiple contact transducer in which the face shown is constructed as a series of portions or plugs 31 of a conductive-adhesive composition in accordance with the invention, for example, as described specifically above, disposed in an arcuate array in a facing element 32 comprising hypoallergenic skin adhesive material as described above.
  • the whole is carried on a suitable structure, for example, a similarly-shaped polyvinylchloride backing sheet carrying press stud contacts at the appropriate locations for each of the plugs 31.
  • the above transducer provides a means of obtaining mul tiple transducer contact points where an array of independent transducers around the heart is required .
  • the present invention is not l im i ted to the spec i f ic embod iments described above. Th us , for example , the formable composi tion of the invention may be used in the following alternative applications :
  • a stud or a combined backing member and stud can be formed for use in the e.c.g. transducer described above. This could replace the metal press stud and/or combine it with the p.v.c. backing di sc. In either case the unit could be produced by forming e.g. by injection moulding , a polymer composition comprising p.v.c., nylon, polypropylene or like material and metal or metal-coated particles , e .g . silver-coated glass spheres.
  • Metal-coated glass fibre-filled polypropylene may be employed for injection moulded applications, of which conduct ive model railway wheels is one example. At present these are produced from glass f ibre-f i lled polypropylene (for strength) and require that a metal insert "spoke" is incorporated into the injection mould before forming each wheel so as to permit transfer of current from the rim of the wheel to the hub and thence to a d rive motor. Our solution to the problem would greatly simplify the construction process by offering a conductive composition from which a wheel can be formed .
  • Extruded coaxial type cable especially for use in high quality signal transmission, e.g. hi-fi, computers, televi sion, etc.
  • At present such cables have a wire centre onto which is extruded an insulating polymer. This is then wi re wrapped using woven wire along its length (the earthing or screening layer) and then a final polymer layer is extruded onto thi s.
  • the main disadvantages are the complexity of the forming process and the inefficiency of the grounding woven wire layer which has to be woven to give flexibility, but then offers inefficient electrical screening.
  • Our proposal is to replace both of the metal layers by a conductive polymer.
  • Conductive polymer foams By incorporating metal or metal-coated particles into a polymer (e.g. polyurethane) which is then subjected to foaming, we attain a conductive foam which has applications in low static packaging and for the protection/screening of electrical components.
  • a polymer e.g. polyurethane
  • Conductive rubber (or similar material) pressure transducers By incorporating conductive particles into a rubber material exactly at the critical percolation volume, we can obtain a material whose conductivity changes markedly on compression and reversibly on decompression (because of rubber recovery). This offers 3 means of providing pressure control in electrical circuitry, for example, in foot-operated control circuits such as sewing machines. It is to be understood, of course, that such materials would have a conductivity far in excess of that of graphite filled rubber, for example, by a factor of about 100.

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Abstract

Composition polymère façonnable dotée de propriétés de conductivité électrique. Sous son aspect le plus vaste, cette composition contient un matériau polymère façonnable où est dispersé un matériau électriquement conducteur sous forme particulaire comprenant des particules métalliques ou enduites de métal; la quantité de matériau conducteur présent suffit à conférer à la composition une conductivité spécifique totale d'au moins 2 mho cm-1 environ. Dans un aspect préférentiel, cette composition contient un ou plusieurs composants afin de donner une composition possédant des propriétés de colle de contact pouvant être utilisée dans la production d'un transducteur. Un tel transducteur comporte un organe de support (11) à travers lequel est fixé un contact électriquement conducteur (12); un fil électrique peut ainsi être connecté à une partie du contact à l'arrière (14) de l'organe de support et le contact prévoit un parcours électriquement ininterrompu à travers l'organe de support jusqu'à une partie de ladite composition adhésive électriquement conductrice (28) formant au moins une partie d'une couche adhésive disposée sur le devant de l'organe de support, ce qui permet au devant du transducteur d'adhérer à la peau. Le dispositif de transducteur décrit ci-dessus trouve son utilité dans des applications recourant à un électro-cardiogramme.
EP84900090A 1982-12-11 1983-12-09 Composition polymere fa onnable Withdrawn EP0128919A1 (fr)

Applications Claiming Priority (2)

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GB8235385 1982-12-11
GB8235385 1982-12-11

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EP0128919A1 true EP0128919A1 (fr) 1984-12-27

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EP (1) EP0128919A1 (fr)
JP (1) JPS60500575A (fr)
AU (1) AU2336984A (fr)
WO (1) WO1984002423A1 (fr)

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US4740657A (en) * 1986-02-14 1988-04-26 Hitachi, Chemical Company, Ltd Anisotropic-electroconductive adhesive composition, method for connecting circuits using the same, and connected circuit structure thus obtained
GB2197791A (en) * 1986-11-21 1988-06-02 Goldhon Ltd Electrically-conductive electrode for medical purposes
US5211174A (en) * 1990-09-14 1993-05-18 Physiometrix, Inc. Low impedance, low durometer, dry conforming contact element
AU667199B2 (en) * 1991-11-08 1996-03-14 Physiometrix, Inc. EEG headpiece with disposable electrodes and apparatus and system and method for use therewith
US5762830A (en) * 1995-10-23 1998-06-09 Hoechst Celanese Corporation Electronically and thermally conducting compositions for actuators
AUPQ788400A0 (en) * 2000-05-30 2000-06-22 Wildon, Michael Peter Epicardial stimulation lead
DE50205953D1 (de) * 2001-09-06 2006-04-27 Fraunhofer Ges Forschung Elektrisch leitfähige teilchen, insbesondere zum einbringen in flüssige medien und verfahren zur deren herstellung
JP4600282B2 (ja) 2003-08-08 2010-12-15 住友電気工業株式会社 導電性ペースト
US7857998B2 (en) * 2008-11-24 2010-12-28 E. I. Du Pont De Nemours And Company High conductivity polymer thick film silver conductor composition for use in RFID and other applications
CN102079847A (zh) * 2009-11-27 2011-06-01 东莞市立高电子制品有限公司 一种光敏银浆导电胶及其制备方法
US8608984B1 (en) 2010-02-23 2013-12-17 Cleveland Medical Polymers, Inc. Polymer nano-composites as dry sensor material for biosignal sensing
EP2868269A1 (fr) * 2013-11-05 2015-05-06 Cleveland Medical Polymers, Inc. Nanocomposites de polymères comme matériaux secs pour la détection de biosignaux
JP6855045B2 (ja) * 2015-11-30 2021-04-07 東海光学株式会社 脳活動計測用電極、その電極を使用した頭部装着装置及び脳活動計測システム
WO2017112367A1 (fr) 2015-12-22 2017-06-29 3M Innovative Properties Company Œillet pour électrode biomédicale et procédé de production associé
WO2017112368A1 (fr) 2015-12-22 2017-06-29 3M Innovative Properties Company Capteur en une seule pièce pour une bioélectrode et procédés pour sa production
EP3393350B1 (fr) 2015-12-22 2023-08-16 3M Innovative Properties Company Capteur pour électrode et procédés de production

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FR1533642A (fr) * 1966-08-05 1968-07-19 Hysol Corp Nouvelles compositions conductrices résineuses
US3746662A (en) * 1971-08-09 1973-07-17 Du Pont Conductive systems
US4098945A (en) * 1973-07-30 1978-07-04 Minnesota Mining And Manufacturing Company Soft conductive materials
US3983075A (en) * 1974-06-21 1976-09-28 Kennecott Copper Corporation Copper filled conductive epoxy
US4490283A (en) * 1981-02-27 1984-12-25 Mitech Corporation Flame retardant thermoplastic molding compounds of high electroconductivity

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AU2336984A (en) 1984-07-05
WO1984002423A1 (fr) 1984-06-21
JPS60500575A (ja) 1985-04-25

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