WO1998002088A1

WO1998002088A1 - Biomedical electrode

Info

Publication number: WO1998002088A1
Application number: PCT/US1996/011668
Authority: WO
Inventors: Nikolaus Loutis; Derek Wright; Paul Weidenhaupt
Original assignee: Minnesota Mining And Manufacturing Company
Priority date: 1996-07-15
Filing date: 1996-07-15
Publication date: 1998-01-22
Also published as: AU6492496A; GB9625533D0

Abstract

A biomedical electrode comprises a connector stud (1) anchored in a patch of adhesive-coated backing material (7) which is used to secure the electrode to the skin of a patient. The connector stud (1), which is located in a pierced opening in the backing material (7), has a head portion (2) to which an electrical lead of an electromedical monitoring/diagnostic system can be attached, and an electrode plate (3) which, when the biomedical electrode is in use, is placed in electrical communication with the skin of the patient. The head portion (2) and the electrode plate (3) of the stud are located on opposite sides of the backing material (7), which is held between the electrode plate and an integral flange (4) of the stud. A method to make the electrode is also described.

Description

BIOMEDICAL ELECTRODE

Field of the Invention

The present invention relates to biomedical electrodes, that is electrodes which can be attached to the skin of a patient to establish an electrical connection between the skin and an eiectromedical monitoring/diagnostic/therapeutic system. The invention relates more especially, but not exclusively, to ECG electrodes for use in a part of a system for monitoring and/or diagnosing cardiac function and is likewise applicable to electrodes for use in electroencephalograph (EEG) systems.

Background of the Invention

ECG monitoring systems are well known and are used in a variety of health care situations. Such systems require the use of electrodes which are attached to the skin, at selected points of the body, to enable electrical signals (indicative of cardiac function) to be fed to an electrocardiograph. The electrodes, which are conventionally attached to the skin by an adhesive, are required to make good electrical contact with the skin and to be constructed to permit the easy attachment of electrical leads from the electrocardiograph. One known type of ECG electrode comprises a connector stud having a head portion to which electrical leads can be attached, and an electrode plate through which contact is made to the skin The stud is located in a patch of backing material, with the electrode plate positioned on one side of the material and the head portion on the other. The side of the backing material on which the electrode plate is positioned is coated with an adhesive, enabling the ECG electrode to be securely attached to the skin and an electrical contact to be formed between the skin and the electrode plate. To improve the electrical connection between the skin and the electrode plate, the latter may, for example, be coated with a layer of an ionically-conductive paste, cream or gel, or covered with a layer of sponge material in which an ionically-conductive gel is embedded Connector studs which are formed in two parts, designed to snap together, are known. One part of the stud provides the electrode plate and the other part provides the head portion and, during the process of assembling the electrode, the two parts are located on opposite sides of the backing material and snapped together, thereby clamping the backing material between them. The connector stud is thus well anchored in the backing material so that the likelihood of it separating from the backing material when the electrode is in use is comparatively low. However, the two-part construction of the stud increases the complexity of the assembly process. Biomedical electrodes with one-piece connector studs are also known.

US-A-4 352 359, for example, describes an electrode in which the connector stud is a one-piece stud, the head portion of which is located in a punched aperture in a patch of adhesive tape. The adhesive tape overlies the upper surface of the electrode stud and aids in holding the electrode securely to the skin of a patient. In another known electrode which employs a one-piece stud, the backing material is a comparatively thick foam material and an integral flange is provided in the stud at a distance from the electrode plate so that it will overlie the upper surface of the backing material. Additional shaping in the form of a smaller flange is provided on the stud between the flange and the electrode plate. The stud is located in a punched aperture in the backing material with the additional shaping on the stud thus being located within the aperture. The use of one-piece connector studs reduces the number of components required to assemble a biomedical electrode but can increase the likelihood of the stud separating from the backing material, particularly when electrical leads are being attached to the stud. Alternatively, if the connector stud is shaped so that it is less likely to separate from the backing material, the insertion of the stud into the backing material during the assembly process can become more difficult.

US-A-3 841 312 and 4 117 846 describe biomedical electrodes in which a separate ring or washer is employed to ensure that the connector stud is well anchored in a backing material. Summary of the Invention

The problem with which the present invention is concerned is that of enabling biomedical electrodes to be produced more simply and in a less costly manner without adversely affecting their reliability when in use.

The present invention provides a connector stud for a biomedical electrode, comprising, a rounded head portion to which an electrical connector can be attached; an integral, generally circular electrode plate at the base of the stud; an integral, generally circular flange which projects from the stud at a distance from the electrode plate and has a transverse dimension which is at least 1.3 times the transverse dimension of the head portion; and a stem portion between the electrode plate and the flange, the space between electrode plate and the flange being uninterrupted by other projections from the stem portion and forming a location for an electrode backing material. The present invention also provides a biomedical electrode comprising a backing material securable by an adhesive to the skin of a patient, and a one-piece connector stud located in a pierced opening in the backing material, the stud having an electrode plate located on one side of the backing material for electrical connection to the skin of the patient and, on the other side of the material, a head portion to which an electrical connector can be attached.

The present invention further provides a method of manufacturing a biomedical electrode, comprising the step of: inserting a one-piece connector stud into a pierced opening in a backing material, the stud having an electrode plate for electrical connection to the skin of a patient and a head portion to which an electrical connector can be attached, the stud being located in the backing material with the electrode plate and the head portion on opposite sides of the material.

In accordance with the invention, there is further provided a biomedical electrode comprising an electrode member to which an electrical connector can be attached, the electrode being securable by an adhesive to the skin of a patient to position a surface of the electrode member adjacent the skin and in electrical connection therewith, wherein the adhesive comprises a strip of pre-cured ionically-conductive adhesive which is laminated to the said surface of the electrode member

By way of example only, embodiments of the invention will be described with reference to the accompanying drawings

Brief Description of the Drawings

Fig. 1 is a perspective view of a connector stud for an ECG/EEG electrode, in accordance with the invention,

Fig 2 shows a longitudinal cross-section on an enlarged scale through the stud of Fig 1,

Fig. 3 is a perspective view, from above, of an ECG electrode incorporating the stud of Figs 1 and 2,

Fig 4 is a view from below of the electrode shown in Fig 3,

Fig 5 is an enlarged, diagrammatic end view in the direction of the arrow V in Fig 4,

Fig 6 shows a cross-section on the line VI- VI in Fig 5,

Fig 7 is a view, similar to Fig 4, of an assembly of three electrodes on a strip of liner material,

Fig 8 illustrates, schematically, the process for the production of an assembly of electrodes as shown in Figs 7,

Fig 9 illustrates, schematically, the insertion of connector studs into backing material in the process illustrated in Fig 8, and

Fig 10 illustrates apparatus for carrying out the process illustrated in Fig 9

Embodiments of the Invention

The connector stud 1 shown in Figs 1 and 2 is a one-piece moulded component comprising a rounded head portion 2, a circular electrode plate 3 at the base of the stud, an outwardly projecting circular flange 4 which extends completely around the head portion 2 at the base of the latter, and, between the electrode plate 3 and the flange 4, a stem portion 5 The stem portion 5 is smooth, as can be seen from Fig 2, so that the space 6 between the electrode plate and the flange is uninterrupted by any projections from the stem portion 5

When in use in a biomedical electrode as described below, the bottom surface of the electrode plate 3 of the stud will be placed in electrical communication with the skin of a patient and the stud 1 will then provide an electrical connection between the patient's skin and the head portion 2 of the stud, to which one lead of an electromedical monitoring/diagnostic system is connected To enable the connector stud to be held in contact with the patient's skin, the stud is anchored in a piece of adhesive-coated backing material which is located, as will be described below, in the space 6 between the electrode plate 3 and the flange 4 The stud 1 is preferably formed of a plastics material, for example a copolymer of acrylonitrile, butadiene and styrene (ABS), with a coating la of an electrically-conductive material, for example silver/silver chloride It may, however, be formed of any other material known to be suitable for the connector studs of biomedical electrodes, for example stainless steel or aluminium

Typically, the diameter of the electrode plate 3 is about 10 3 mm, the maximum transverse dimension of the head portion is about 3 5 mm, the diameter of the flange 4 is about 5.5 mm, the diameter of the stem is about 3 0 mm, the height of the stud 1 is about 6 0 mm and the width of the space 6 is about 1 0 mm An ECG electrode incorporating the stud 1 is shown in Figs 3 to 6

The stud 1 is positioned in an opening (not visible) in the centre of a generally square patch of non-conductive backing material 7, with the backing material being held in the space 6 in the stud In that way, the stud 1 is anchored in the backing material 7 with the electrode plate 3 located on one side of the material, and the flange 4 and head portion 2 located on the other As will be described in greater detail below, the opening in the backing material (in which the stud 1 is located) is preferably a pierced opening but it could, alternatively, be a punched opening

The backing material 7 is typically a synthetic foam material, for example a 1 mm thick polyethylene foam film, about 34 mm x 37 mm with rounded corners The rear surface of the backing material 7 is provided with an adhesive coating comprising a pressure-sensitive adhesive 8, (which adhesive is preferably biocompatible with mammalian skin,) over which is a central strip 9 of an ionically- conductive adhesive which extends across the patch of backing material from one of the shorter edges to the other, covering the bottom surface of the electrode plate 3 of the stud and leaving two outer strips of the pressure-sensitive adhesive exposed. The central strip 9 of ionically-conductive adhesive is typically about 20 mm wide and the outer strips of pressure-sensitive adhesive 8 are each about 7 mm wide.

The adhesive coatings 8, 9 on the backing material can be protected during storage until use by a removable liner 10 (shown as being transparent) which may be formed from any suitable material, for example a siliconated polyester film having a thickness of about 0.05 mm. A paper tab 13, typically about 3 mm wide, is located over the pressure-sensitive adhesive 8 along one of the longer edges of the backing material 7, and assists in removing the electrode from the liner 10.

To ensure that the stud 1 will be well anchored in the backing material 7, the diameter of the flange 4 is preferably at least 1 .3 (more preferably 1.5) times the maximum transverse dimension of the head portion 2. A process by which a connector stud 1 having a flange 4 of that size can be inserted into the backing material 7, and be well anchored, will be described below.

Fig. 7 illustrates one convenient way in which electrodes of the type shown in Figs. 3 to 6 can be supplied to the user. As shown in Fig. 7, three electrodes 1 1, each of the type shown in Figs. 3 to 6, are mounted in a line on a strip of corresponding-shaped liner material 12 (corresponding to the liner material 10 of Figs. 4 to 6). The electrodes 1 1 are separated from each other at the lines 1 la and can, accordingly, be removed individually from the liner material 12 with the assistance of the respective paper tab 13 and attached to the skin of the patient. It will be appreciated that the number of electrodes 1 1 provided on the single strip 12 of liner material can be varied but, since three electrodes are typically required at a time, three electrodes per strip of liner material is particularly convenient for the user. When the electrodes have been placed on the patient's body, typically the upper torso, the electrical leads from the electrocardiograph are attached to the head portions 2 of the electrode studs 1. That may be done in any appropriate way but, typically, the leads are provided with connectors which can either be pushed, or clamped, onto the head portions of the studs

The pressure-sensitive adhesive 8 on the electrode backing material 7 can be any appropriate pressure-sensitive adhesive known to be suitable for use on biomedical electrodes Suitable adhesives include acrylate ester adhesives, and more particularly acrylate ester copolymer adhesives Such adhesives are generally described in US Patent Nos 2 973 826, Re 24 906, Re 33 353, 3 389 827, 4 1 12 213, 4 310 509, 4 323 557, 4 732 808, 4 917 928, 4 917 929, and European Patent Publication 0 051 935. The ionically-conductive adhesive 9 on the electrode backing material 7 can be any appropriate ionically-conductive adhesive known to be suitable for use on biomedical electrodes Ionically-conductive adhesives useful in connection with biomedical electrodes are described in US Patent Nos 4 524 087, 4 539 996, 4 848 353, 5 133 356, 5 225 473, 5 276 079, 5 338 490, 5 362 420, 5 385 679, and WO-A-95/20634 and WO-A-94/ 12585

The strip of ionically-conductive adhesive 9 may be coated onto the electrodes 1 1 and then cured In that case, the adhesive 9 need not be applied as a strip but could, for example, be applied over the whole of the rear surface of the backing material 7 (including the bottom surface of the electrode plate 3 of the connector stud 1 ) Alternatively, as described below, the adhesive may be pre-cured and a strip of the pre-cured adhesive may be laminated to the electrodes The strip of pre-cured adhesive can be as wide as desired, provided that it ensures adequate electrical contact between the electrode plate 3 and the skin of the patient The strip of pre-cured adhesive may, for example, be wide enough to cover the whole of the rear surface of the backing material 7

Depending on the degree of adhesion of the ionically-conductive adhesive 9 to the pressure-sensitive adhesive 8, it may be advantageous to include a scrim material between the adhesives to ensure a good adhesion of the conductive adhesive to the backing material so that, when the electrodes are removed from the skin of the patient, all the conductive adhesive is also removed and no residue remains on the skin The use of an ionically-conductive adhesive to provide the physical and electrical contact between the electrode plate of the stud and the patient's skin is preferred but is not essential As an alternative, a strip of scrim material could be applied across the electrode (in the same location as strip of adhesive 9) and a known type of ionically-conductive gel could then be embedded in the scrim material

It will be appreciated that, when areas of both pressure-sensitive and ionically-conductive adhesive are present on the back of the electrode, the size and location of those areas can be varied, provided that the electrode will adhere effectively to the skin of a patient and that an effective electrical contact can be established between the electrode plate 3 or the connector stud 1 and the patient's skin

The non-conductive backing material 7 of the electrode can be any appropriate material, of any suitable thickness and shape (e.g round, oval, rectangular) When the material is polyethylene foam, the most suitable thicknesses are within the range of from 0 75 to 1 5 mm Other suitable materials, apart from the polyethylene foam described above include polyester non-woven materials, cellulose rayon non-woven materials, and polyethylene vinyl acetate films When backing material is used which has a different thickness from the backing material 7 of Figs. 3 to 6, the distance between the base 3 and the flange 4 of the connector stud 1 should be increased or decreased accordingly

A process for producing electrode assemblies as shown in Fig 7 will now be described with reference to Fig 8 The process preferably comprises the following steps (i) A continuous strip of electrode backing material 19, coated with a pressure-sensitive adhesive which is protected by a paper release liner, is fed through a cutting station 20 in which a continuous strip of the paper release liner is removed, in a location corresponding to the intended location of the connector studs in the finished electrodes. (ii) The backing material 19 is then fed to a stud insertion station

21 , described in greater detail below, in which spaced connector studs are anchored in the strip of the backing material from which the paper liner has been removed The paper release liner that remains on the backing material 19 after step (i) imparts stability to the backing material while the connector studs are being inserted

(iii) The backing material 19 is then fed to another cutting station 22 in which more of the paper liner is removed adjacent the line of connector studs, leaving an exposed strip of pressure-sensitive adhesive which is slightly wider than the intended width of the strip of conductive adhesive in the finished electrodes

(iv) The backing material 19 is then fed to a laminating station 23 in which a strip 24 of pre-cured ionically-conductive adhesive is applied over the pressure -sensitive adhesive and the line of connector studs The adhesive strip 24 is backed by a release liner 25 which is removed at the station 26 after the adhesive has been applied to the backing material

(v) The backing material 19 is then fed to a further cutting station (not illustrated) in which more of the paper liner is removed from the pressure- sensitive adhesive, leaving a strip of paper liner to form the paper tab 13 (as in Fig. 7) in the finished product.

(vi) The liner material 27 for the finished product is then applied over the adhesive in station 28.

(vii) The final laminated assembly, comprising backing material, connector studs, adhesives, paper tab and product liner is then fed to a final cutting station 29, in which the backing material 19 is cut along the lines 1 la (Fig. 7) and the product liner material 27 and backing material 19 are both cut to form strips each holding three electrodes. The formation of the cuts 1 la and the cutting of the backing material and product liner into strips may be carried out consecutively or simultaneously The waste material is then removed, as indicated at 30

The process described above can, if required, be carried out in such a way that two, or more, rows of electrodes are produced simultaneously across the width of the backing material 19

The manner in which the connector studs are inserted into the backing material in the station 21 of Fig 8 will now be described with reference to Figs 9 and 10 The backing material 19, from which the strip of paper release liner has been removed, passes over a piercing head 31 comprising a piercing tool 32 surrounded by a tubular sleeve 33 The adhesive-coated side of the backing material is uppermost as seen in Fig 9 (i e it is the side remote from the piercing head 31) In steps (a) and (b), the piercing tool 32 is pushed through the backing material 19 in the region from which the paper liner has been removed In step (c), the sleeve 33 is pushed through the pierced opening 34 in the liner and holds it open while the piercing tool is withdrawn Subsequently, in steps (d) to

(g), a connector stud 35 is placed (head portion first) into the end of the tubular sleeve 33 and is held in place, with the electrode plate 3 of the stud engaging the end of the sleeve, as the latter is withdrawn through the opening 34 The stud is then released, in step (h) when it has reached the position in which the edges of the pierced opening are located in the space 6 (Figs 1 and 2) between the electrode plate 3 and the flange 4 of the stud The backing material then passes to the station 22 of Fig. 8 It will be appreciated that, to prevent the connector studs 35 slipping into the tubular sleeve 33, the electrode plate 3 of each stud should have a diameter greater than that of the sleeve (and therefore, of the flange 4) To enable the backing material 19 to lie flat around the stem 5 of each stud, the stem 5 should have as small a diameter as possible, preferably not more than 0 75 times that of the flange 4

Advantageously, the process illustrated in Fig 9 is carried out continuously in the manner illustrated in Fig. 10 The backing material 19 passes over a continuously-driven insertion wheel 40 containing a plurality of radially- located piercing tools 32 and surrounding tubular sleeves 33 The piercing tools and sleeves 32, 33 are cam driven so that they each move uniformly in and out of the insertion wheel 40 in the manner illustrated in Fig 9 The backing material 1 is initially held against the insertion wheel 40 by a first belt 41 while the pierced openings are being formed Connector studs 1 to be placed on the ends of the sleeves 33 are then fed into position at 42 and held in place by a second belt 43 as the sleeves are withdrawn to locate the studs in the backing material 19 which is then removed as indicated at 44 A pre-cured conductive adhesive for use in step (iv) of the process described above with reference to Fig 8 can be prepared according to the following procedure A precursor is prepared, having the following formulation (by weight) 18 61% acrylic acid, 0 05% 2,2-dimethoxy-2-phenyl acetophenone, 0 09% 4-(2- hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone; 0 04% methylene bis(acrylamine), 41.39% glycerine; 21 35% deionized water; 0 09% guar gum; 16 53% NaOH (50% sol), 1 85% potassium chloride. The precursor can be prepared in the following manner. A kettle equipped with overhead stirrer and a cooling jacket is charged with the acrylic acid, 2,2-demethoxy-2-phenyl acetophenone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-methylpropyl)ketone, methylene bis(acrylamide), glycerin, guar gum, and a proportion of the deionized water To the well stirred solution is charged the 50% aqueous NaOH portionwise maintaining the batch temperature below 38 °C. The hydroxide line is rinsed with deionized water and stirred, and the potassium chloride is then added as a 25% aqueous solution to yield a coater-ready precursor The precursor is coated onto a siliconized polyester liner at 0 6 mm thick, overlaminated with a siliconized polyester liner, and passed through a curing chamber consisting of banks of fluorescent "black" lights, exposing the material to an intensity of 1 0 mW/sqcm and a total dose of 315 mJ/sqcm Following removal of one of the polyester liners, the cured conductive adhesive so prepared is ready for use in the laminating station 23 of Fig. 8

To facilitate the handling of the cured adhesive and, if necessary, enable it to be transported from the location in which it is cured to the laminating station 23, a scrim material may be located on the liner material onto which the adhesive precursor is coated Following curing, the scrim material will be embedded in the adhesive layer, towards one side of the latter The cured adhesive should then be applied to the backing material 19 (Fig 8) with the scrim nearest to the backing material.

A tubular sleeve, similar to the sleeve 33 of Fig 9, can also be used when it is required to insert a stud of the type shown in Figs 1 and 2 into a punched (rather than pierced) hole in electrode backing material 7 and will facilitate the location of the stud in the hole, despite the comparatively large diameter of the flange 4 of the stud 1. When the stud is in position in the backing material, the comparatively large diameter of the flange 4 again ensures that the stud is well anchored in the backing material 7. It will be appreciated that, although a continuous process as illustrated in Figs 9 and 10 is preferred in that it enables a fast production rate to be achieved (and the cost of producing electrodes to be reduced), it is not essential since the same process could be carried out intermittently.

It will also be appreciated that the process could be used to produce electrodes having a different form from that shown in Fig.3. For example, the overall shape of the connector studs 1 could be varied, as could the shape of the patches 7 of backing material. In addition, individual features of the process could be applied to the production of other forms of electrodes. For example, the step 26 (Fig. 8) of laminating a strip of pre-cured conductive adhesive to the backing material could be used in the production of many other types of biomedical electrodes, including electrodes which do not incorporate a connector stud. More specifically, strips of pre-cured conductive adhesive could be used in biomedical electrodes of the type which comprise a patch of an ionically-conductive material which is secured directly to the skin and to which an electrical lead of an electromedical monitoring/ diagnostic/ therapeutic system can be attached In that case, a strip of pre-cured adhesive could be laminated across the rear surface of the patch of ionically-conductive material.

Suitably-shaped and sized electrodes of the general type shown in Figs. 3 to 6 can be also used in association with EEG systems. Likewise, biomedical electrodes of the present invention can be connected electrically and mechanically to electrosurgical generators or cardiac stimulation devices to provide dispersive electrode connection or cardiac stimulation electrode connection, respectively Electrosurgical generators are commonly available and known to those skilled in the art, such as devices marketed by Birtcher Medical Systems, Inc. Of Irvine, California, USA; Aspen Surgical Systems, Inc. Of Utica, New York, USA; and Valleylab. Inc. Of Boulder, Colorado, USA Cardiac stimulation devices for cardioversion, external pacing, and defibrillation are commonly available and known to those skilled in the art, such as devices marketed by Hewlett-Packard Corporation of McMinnville, Oregon, USA, Zoll Medical Corporation of Newton, Massachussetts, USA and Physiocontrol Corporation of Redmond, Washington, USA.

Embodiments of the invention have been described. The claims follow.

Claims

What is claimed is

1 A connector stud for a biomedical electrode, comprising, a rounded head portion to which an electrical connector can be attached, an integral, generally circular electrode plate at the base of the stud, an integral, generally circular flange which projects from the stud at a distance from the electrode plate and has a transverse dimension which is at least 1 3 times the transverse dimension of the head portion; and a stem portion between the electrode plate and the flange, the space between electrode plate and the flange being uninterrupted by other projections from the stem portion and forming a location for an electrode backing material

2. A connector stud as claimed in claim 1, in which the flange has a transverse dimension which is at least 1 5 times the transverse dimension of the head portion

3. A connector stud as claimed in claim 1 or claim 2, in which the electrode plate has a transverse dimension at least equal to that of the flange

4 A connector stud as claimed in any one of the preceding claims, in which the stem has a transverse dimension less than 0 75 times that of the flange

5 A connector stud as claimed in any one of claims 1 to 4, in which the stud is a moulded plastics component coated with an electrically-conductive material

6. A connector stud as claimed in claim 5, in which the stud is formed from a copolymer of acrylonitrile, butadiene and styrene and is coated with silver/silver chloride

7. A biomedical electrode comprising: a connector stud as claimed in any one of the preceding claims; and an electrode backing material located in the space between the electrode plate and the flange of the stud, the electrode backing material being securable by an adhesive to the skin of a patient with the electrode plate of the stud located adjacent the skin

8. A biomedical electrode comprising a backing material securable by an adhesive to the skin of a patient, and a one-piece connector stud located in a pierced opening in the backing material, the stud having an electrode plate located on one side of the backing material for electrical connection to the skin of the patient and, on the other side of the material, a head portion to which an electrical connector can be attached.

9. A biomedical electrode as claimed in claim 7 or claim 8, including a layer of ionically-conductive material on the electrode plate of the stud.

10. A biomedical electrode as claimed in any one of claims 7 to 9, in which the backing material is provided with an adhesive layer to enable the electrode to be releasably adhered to the skin.

1 1. A biomedical electrode as claimed in claim 10, in which the adhesive layer includes an ionically-conductive adhesive located at least on the electrode plate of the stud.

12. A biomedical electrode as claimed in claim 1 1 , in which the ionically-conductive adhesive is in the form of a pre-cured strip which is laminated to the backing material and the electrode plate.

13. A biomedical electrode as claimed in claim 1 1 or claim 12, in which the adhesive layer also includes a pressure-sensitive adhesive.

14. A biomedical electrode as claimed in any one of claims 10 to 13, in which the adhesive-carrying side of the electrode is covered by a removable liner material.

15. A biomedical electrode as claimed in claim 14, in which the backing material has a non-adhesive margin to facilitate the separation of the electrode and the liner material.

16. A biomedical electrode as claimed in any one of claims 7 to 15, in which the backing material comprises a synthetic foam material

1 7 A method of manufacturing a biomedical electrode, comprising the step of. inserting a one-piece connector stud into a pierced opening in a backing material, the stud having an electrode plate for electrical connection to the skin of a patient and a head portion to which an electrical connector can be attached, the stud being located in the backing material with the electrode plate and the head portion on opposite sides of the material.

18. A method as claimed in claim 17, including the step of holding the pierced opening in an open condition while the stud is being inserted

19. A method as claimed in claim 17 or claim 18, including the steps of: holding the opening in an open condition by inserting a tubular member through the opening from one side of the backing material; locating the stud, head portion first, in the end of the tubular member from the other side of the backing material; and withdrawing the tubular member through the opening while holding the stud in the end of the tubular member, to locate the stud in the backing material

20 A method as claimed in claim 19, in which the backing material is coated with a pressure-sensitive adhesive on the said other side

21. A method as claimed in any one of claims 17 to 19, including the step of laminating a cured, electrically-conductive adhesive to the electrode across the backing material and the electrode plate of the stud

22 A method as claimed in any one of claims 19 to 21 , the method steps being carried out repeatedly without interruption to form a plurality of electrodes

23 A biomedical electrode comprising an electrode member to which an electrical connector can be attached, the electrode being securable by an adhesive to the skin of a patient to position a surface of the electrode member adjacent the skin and in electrical communication therewith, wherein the adhesive comprises a strip of pre-cured ionically-conductive adhesive which is laminated to the said surface of the electrode member

24 A biomedical electrode as claimed in claim 23, in which the electrode member comprises a connector stud anchored in a backing material, and the strip of pre-cured ionically-conductive adhesive is also laminated to the backing material

25. A biomedical electrode as claimed in claim 24, in which the said surface of the connector stud is located on one side of the backing material, and the stud has a head portion, located on the other side of the backing material, to which an electrical connector can be attached