CN101001663A - Method for making electrical conductors - Google Patents

Abstract

A method for manufacturing an electrical lead (10), the electrical lead (10) having one or more electrodes (11), the method comprising providing an elongate member (14), the elongate member (14) having at least one polymeric region and further having at least one electrical conductor (13), the electrical conductor (13) extending along at least part of a length of said elongate member (14) and being housed within a wall of said elongate member. Accessing a length of the at least one electrical conductor (13) at the at least one polymer region (34). A conductive adhesive (15) is applied to the length of the at least one electrical conductor (13) being accessed.

Description

Method for making electrical conductors

Cross References to Related Applications

This application claims priority to US Provisional Patent Application 60/599,651, filed August 5, 2004, and US Provisional Patent Application 60/648,232, filed January 28, 2005.

technical field

The present invention relates to the manufacture of electrical leads, and more particularly to methods for making electrical leads, such as conductive catheters, and to electrical leads.

Background technique

The electrical activity of the muscles in the heart directs the overall activity of the heart. Many cardiac malfunctions, especially arrhythmias, are evidenced by or caused by electrical activity not applicable to the normal functioning of the heart. The electrical leads described herein are useful in the detection of cardiac electrical activity and in cardiac therapy through stimulation, ablation and defibrillation.

Electrical leads with electrode regions are already used in the medical field, for example for the aforementioned applications.

Traditionally, electrodes made from machined metal or coiled wire, which, while possessing the requisite electrical conductivity, do not provide the desired degree of flexibility required in medical applications.

While the use of metal-coated or metal-filled polymers has been considered as medical electrodes, the amount of metal required to achieve an adequate level of conductivity renders the resulting wire stiff and less suitable for implantation into a patient.

Contents of the invention

According to a first aspect of the present invention there is provided a method for manufacturing an electrical lead having one or more electrodes, the method comprising:

providing an elongated member having at least one polymer region and further having at least one electrical conductor extending along at least part of a length of said elongated member and received within a wall of said elongated member;

access a length of at least one electrical conductor at at least one polymer region; and

Applying a conductive adhesive to said length of at least one electrical conductor that has been accessed.

One or more discrete electrodes may be formed along a length of the elongate member. The electrode may comprise a band extending at least partially around the circumference of the elongate member.

The conductive adhesive may comprise any of a variety of materials derived from inherently conductive adhesives, adhesive bases comprising solid conductive fillers, adhesive bases comprising dissolved conductive materials, and mixtures of these materials. Adhesive bases comprising curable or settable polymeric materials are also suitable for this purpose, such as polymers that are not tacky or sticky after curing or setting. Epoxy resins containing particulate or fibrous metals are suitable choices, especially highly conductive biocompatible metals such as silver, gold, platinum, palladium, rhodium, and mixtures thereof, as well as Regions of these metals are constructed of alloys. One option could include silver filled epoxy.

A further step of applying at least one conductive material to the conductive adhesive may be performed. Again, the conductive material may be any of a variety of materials, but particularly suitable are those capable of forming a conductive layer between the conductive adhesive and any further material disposed outside of the at least one conductive material.

A suitable type of these conductive materials to be applied to the adhesive may be a liquid carrier, especially a volatile carrier such as variously comprising solvated or complexed conductors or comprising solid conductors solvent. A subclass of these materials may be inks comprising particulate conductive metals, alloys or structures such as silver or silver coated with metals such as platinum or palladium.

The conductive adhesive or the conductive material applied to the conductive adhesive may further be covered thereon with, for example, the aforementioned conductive metal. The metal can include platinum.

The elongated member may include a plurality of electrical conductors, and the method may include accessing a length of each of the plurality of electrical conductors at circumferentially spaced intervals around the elongated member, and applying a conductive adhesive to the Pads are applied to the length where each electrical conductor is accessed.

The method may include applying a layer of at least one electrically conductive material to each pad of the electrically conductive adhesive. Additionally, the method may include covering each pad of the conductive adhesive with a metal layer comprising platinum or palladium.

The pads of conductive adhesive may be arranged in longitudinally aligned relationship around the circumference of the elongated member, and the method may comprise applying said metal layer as a continuous layer around the circumference of the elongated member, and thereafter, for example by laser cutting The layer is separated into a plurality of electrically insulating segments arranged at circumferentially spaced intervals to form a plurality of discrete electrodes arranged about the circumference of the elongated member.

The method may include applying a metal including platinum by mounting a ring on the elongated member and securing the ring in place. The ring can be secured by adhesive, crimping, and the like.

The electrical lead may include a plurality of conductors extending along at least part of a length of the electrical lead. While one or more conductors may be specifically associated with an electrode, the electrical lead may comprise additional conductors forming part of the temperature sensing component. A temperature sensing component may be associated with the electrode in such a way that it determines the temperature at said electrode. In order to determine the temperature at said electrode, the temperature sensing part may be electrically insulated from the corresponding electrode.

Accordingly, the method may comprise the further step of insulating the electrical contact of the electrical lead from said one or more electrodes. This electrical contact can be insulated by:

access to said electrical contact;

applying a conductive adhesive to the first electrical contact; and

Electrochemically treating the conductive adhesive such that portions of the conductive adhesive are converted to non-conductive portions.

The electrochemical treatment may include the step of passing an electrical current through the electrical contacts so that the electrical current also passes through the conductive adhesive while the conductive adhesive is in an ionic environment containing components intended to form an insulator (or high barrier layer) material. Ionic environments including salt (NaCl) solutions or potassium chloride solutions may be suitable, although other such materials are also contemplated.

Such a step electrochemically converts the metal in the conductive adhesive to metal chloride. Where the conductive adhesive comprises silver filled epoxy, the silver on the surface facing the solution is converted to silver chloride. The silver chloride layer can function as an insulating layer.

The electrical contacts may include portions of temperature sensing components such as thermocouples.

According to a second aspect of the present invention there is provided a method of electrically insulating a first electrical contact of an electrical conductor from a second electrical contact of an electrical conductor, the method comprising:

access to the first electrical contact;

applying a conductive adhesive to the first electrical contact; and

Electrochemically treating the conductive adhesive such that portions of the conductive adhesive are converted to non-conductive portions.

Electrochemical processing may include the step of passing electrical current through the electrical contacts, and thereby the conductive adhesive, to form the insulator. Similar to the steps above, this step can be performed in an ionic environment containing the active material to produce an insulator or highly resistive material. Where silver-containing materials are selected, salt (NaCl) solutions or potassium chloride solutions may be suitable.

Conductive adhesives may include those listed above, including silver-filled adhesives, such as silver-filled epoxies. Again, if so selected, the silver in the portion of the adhesive can be converted to silver chloride (AgCl) using the electrochemical reaction steps discussed above. The silver chloride formed is not conductive.

The first electrical contact may include a temperature sensing component.

The second electrical contact may include an energy transfer electrode. The electrode may transmit energy that forms heat in the tissue against which the electrode is placed in use.

The temperature sensing component may be in thermal contact with the energy transfer electrode.

Temperature sensing components in this variation and others described herein may include thermocouples or other temperature sensing devices, such as RTDs, thermistors, or IC devices, where the frequency or period output is related to temperature. If a thermocouple is selected, suitable choices of conductors may include a first wire made of copper and a second wire made of constantan.

The electrical lead may comprise an elongate member wherein the wires of the thermocouple extend along at least part of a length of the elongate member and may be housed in a wall of the elongate member. A junction may be formed between two wires of the thermocouple connected to the electrodes to form a closed loop thermocouple by applying a conductive adhesive to the wires so that the wires are electrically connected to each other at the junction.

At least one electrically conductive material can be applied to the electrodes and thermocouple junctions.

Broadly, according to a third aspect of the invention there is provided a method of manufacturing an electrical lead, the method comprising:

An elongated member is provided having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor being disposed in the Termination in electrical connection of conductive areas other than elongated parts;

Severing the elongated member away from the conductive area;

forming a non-conductive termination away from the conductive region; and

A conductive material is applied over the conductive region and the terminal to form a terminal electrode of the electrical lead.

More specifically, according to a third aspect of the present invention, there is provided a method of manufacturing an electrical lead, the method comprising:

An elongate member is provided having a proximal end and a distal end, the elongate member has one or more polymeric regions, and additionally has a plurality of electrical conductors along at least a portion of a length of the elongate member extending partially toward the distal end of the elongated member, the electrical conductor being housed within the wall of the elongated member;

For each of at least some of the electrical conductors, a conductive region in electrical contact with its associated electrical conductor is formed by:

accessing a length of each of at least some of the electrical conductors through the polymeric region of the elongated member, and applying a conductive adhesive to each of the accessed electrical conductors;

applying a conductive material at an access point associated with each electrical conductor to form a plurality of longitudinally spaced conductive regions along the length of the elongated member;

cutting the elongated member away from one of the conductive regions;

apply a non-conductive termination away from a conductive area; and

A conductive material is applied to bridge the conductive region and the terminal to form a terminal electrode of the elongated member.

Terminations can be applied in a liquid state. The termination can be applied in two stages.

Thus, the first layer may be applied to seal the distal end of the elongated member. The second layer can be applied and shaped to give the desired shape to the terminal electrode.

Terminations may be fabricated from suitable non-conductive materials including resins. In particular, the termination may be a synthetic resin, such as epoxy.

Alternatively, the termination may be a solid element adhesively secured to the distal end of the elongated member to seal the end and form the desired shape of the terminal electrode.

The desired shape may be a generally domed shape.

The conductive material may be any of a variety of materials. Preferably, the conductive material is applied in two stages. Firstly, the first layer of conductive material can be applied in liquid form. The liquid form may be a liquid carrier, especially a volatile carrier such as a solvent, which liquid carrier contains a solvated or synthetic conductive component or comprises a solid conductive component. Subclasses of these materials may be inks that include particulate conductive metals, alloys, or mechanisms such as silver.

As noted above, the first layer may be applied to the non-conductive terminal as well as to the conductive area to bridge the conductive area and the terminal. The conductive layer can be applied by any suitable method, including brushing, dipping, pad printing, and the like.

This layer may further be covered thereon with a conductive biocompatible material, such as a suitable metal, such as platinum.

According to a fourth aspect of the present invention, an electrical lead is provided, comprising:

An elongated member having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor disposed on the elongated member terminate in conductive areas outside of long parts;

a non-conductive terminal disposed away from the conductive region and at the distal end of the elongate member; and

At least one layer of conductive material bridging the conductive region and the non-conductive terminal to form a terminal electrode of the conductive component.

According to a fifth aspect of the present invention there is provided a method of manufacturing an electrical lead, the method comprising:

An elongated member is provided having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor being in contact with the termination in electrical connection of a conductive region arranged outside the elongated member;

forming an access point in the elongate member to provide access to the at least one electrical conductor;

applying radio opaque material to the area of the elongate member that is longitudinally aligned with, but not in electrical contact with, the access point; and

The conductive region is formed by applying at least one layer of conductive material around the elongated member, making electrical contact with the conductor through the access point, and overlying the radiation opaque material.

According to a sixth aspect of the present invention, an electrical lead is provided, comprising:

an elongate member having a proximal end and a distal end, at least one electrical conductor housed in the elongate member and extending from the proximal end to the distal end of the elongate member;

access points formed in the walls of the elongate member at predetermined locations to provide access to the electrical conductors;

a region of radiopaque material carried by the elongated member in a region of the elongated member longitudinally aligned with, but circumferentially spaced from, the access point; and

At least one layer of electrically conductive material is provided at predetermined locations on the elongated member to provide electrical contact to the electrical conductor through the access point, and overlying said radiation opaque material.

The access points may be in the form of slots arranged transversely in the wall of the elongate member. In this regard, the elongate member may be in the form of a tubular member helically wound with electrical conductors embedded within the wall of the elongate member. Therefore, the slit may be along the winding direction of the conductor.

In one embodiment of this aspect of the invention, the radio-opaque material may be a layer of radio-opaque material applied to the outer surface of the elongated member to form a cuff around the elongated member. The cuff may be in a position diametrically opposite the access point on the elongate member. The radiopaque material can be applied by pad printing.

Thereafter, the method may include applying a layer of conductive material. The layer of conductive material may comprise a first layer, such as the previously mentioned silver ink. The first layer can then be overlaid with a second biocompatible conductive material, such as platinum.

In another embodiment of this aspect of the invention, the radio-opaque material may be inserted into a groove formed in the elongate member. The groove may be formed in a region of the elongate member diametrically opposite the access point. The groove may have any suitable shape, such as a slot, a cross shape, a circle, and the like. In this embodiment, the conductive layer can again be applied in two stages. These layers can be applied by pad printing.

The radiation opaque material may comprise about 70% to 80% non-conductive material and about 20% to 30% adhesive material.

The adhesive material may include epoxy. Preferably, the epoxy of the radiopaque material is matched to the epoxy of the silver ink to facilitate pad printing.

Where the radio-opaque material is received in the recess of the elongate member, the epoxy of the radio-opaque material may be selected to be the same as the epoxy used to fill the access point. This is advantageous for biocompatibility purposes.

Description of drawings

Figure 1 schematically shows a partially cut-away side view of an electrical lead according to an embodiment of the present invention;

Figures 2a to 2f schematically show the steps of a method for manufacturing the electrical lead of Figure 1 according to an embodiment of the present invention;

Figure 3 schematically shows the electrical leads after completing the method;

Figure 4 shows a schematic cross-sectional end view of an electrical lead manufactured by a method according to another embodiment of the invention;

Figure 5 shows a schematic side view of a portion of an electrical lead manufactured by a method according to a further embodiment of the invention;

6a to 6d schematically show the steps of a method of electrically insulating a first electrical contact of an electrical conductor from a second electrical contact of an electrical conductor according to another embodiment of the present invention;

Figures 7a to 7e schematically show the steps of a method for manufacturing an electrical lead according to a further embodiment of the present invention;

Figure 8 schematically shows a three-dimensional view of the initial steps of a method for manufacturing an electrical lead according to yet another embodiment of the present invention;

Figure 9 shows a schematic cross-sectional end view of a first example of an electrical lead manufactured according to yet another method of making an electrical lead;

Figure 10 shows a schematic cross-sectional end view of a second example of an electrical lead manufactured according to yet another method of making an electrical lead; and

FIGS. 11 a to 11 d schematically show variations of the example of the electrical lead shown in FIG. 9 .

Detailed ways

Referring to the drawings, according to an embodiment of the present invention, an electrical conductor manufactured according to a method for manufacturing an electrical conductor is generally indicated by reference numeral 10 .

The electrical lead 10 comprises an elongate member 10a with at least one electrode 11, and preferably with a plurality of strip electrodes arranged at longitudinally spaced intervals along the length of the elongate member 10a. Non-ribbon electrodes are shown as 11b.

Figure 3 shows a side view of the resulting electrical lead 10 functioning as an electrode sheath for a catheter and extending from an introducer 30 or similar device. The lead 10 comprises a plurality of longitudinally spaced electrodes 11, at least some of which are strip electrodes.

As described in the previous paragraph, the electrical lead 10 is used as an electrode cuff for a cardiac catheter. The electrodes 11 are used as sensing electrodes to sense the electrical activity (normal or not) in the muscle of the heart. Furthermore, the electrodes 11 can be used to ablate areas of tissue in the heart to correct some abnormalities.

Thus, each electrode 11 is initially operable as a sensing electrode. Such electrodes 11 enable the clinician to identify areas of electrical disturbance in the patient's heart. This electrical disturbance may be caused by a "mis-firing" damaged area of heart tissue. Once positioned, the same electrode 11 can be switched to ablation function to ablate the damaged tissue.

The multifunctional electrode 11 may in particular be used in the treatment of atrial fibrillation. Atrial fibrillation, an irregular heart rhythm, is caused when areas of heart tissue near the heart "misfire." Such misfiring results in electrical disturbances in the normal electrical pathway as well as in the resulting pulsatile contractions of the atrium. The result is that the atria contract in a rapid and chaotic fashion. If fibrillation is prolonged, the blood in the atria cannot be completely evacuated to the ventricles, leading to several complications. By sensing the area of tissue causing this electrical disturbance, the precise area can then be ablated.

The manufacture of the electrical lead 10 is shown in Figures 2a to 2f. Initially, as shown in Figure 2a, an inner part 12 is provided, manufactured from a suitable polymer such as polyethylene or polyether block amide (PEBAX). Other polymeric materials are also acceptable and can be readily determined from the art.

As shown in Figure 2b, a plurality of conductors 13 are wound around the outer surface of the inner part 12 in a helical fashion. Instead, the conductor 13 is accommodated in a lumen of the inner part 12 . Up to 24 or more conductors 13 may be used in the electrical lead 10 and be helically wound or arranged in the lumen of the inner part 12 .

The conductor 13 is a metal wire. The wires are insulated with a polymer material such as Nylon, polyurethane or nylon-polyurethane copolymer. Examples of suitable conductors include copper or constantan coated with a nylon-polyurethane mixture.

As shown in Figure 2c, an outer polymer sheath 14 is formed, for example by protruding over the inner part 12 and the conductor 13, to form the elongated part 10a. The outer polymeric sheath 14 is fabricated from a material similar to or the same as that of the inner component 12 . However, other materials may be selected as a matter of design choice.

The elongated member 10 a comprising the inner part 12 , the conductor 13 and the outer polymer sheath 14 is heat treated to fix the outer polymer sheath 14 to the inner part 12 and the conductor 13 . It will be appreciated that the wall of the electrical conductor 10 may thus effectively be constituted by an inner layer defined by the inner part 12 , an intermediate layer formed by the helically wound conductor 13 and an outer layer defined by the outer sheath 14 . In fact, the conductor 13 is embedded in the wall and has little, if any, polymer material between adjacent turns of the conductor 13, so there is limited movement between adjacent turns, thereby increasing the electrical The flexibility of the wire 10.

As shown in Figure 2d, the desired length of one or more wires 13 is achieved or exposed by laser cutting portions of the outer sheath 14. Laser cutting is precise and provides a suitable method of removing portion 32 of outer polymer sheath 14 while easily creating opening 34 . The region 34 where the outer polymer sheath has been removed has a width similar to that of the exposed conductor 13 and has a selected length extending along the predetermined length of the conductor 13 following the coiled or helical path of the conductor 13 . The amount of outer polymer sheath 14 removed largely depends on the final electrode 11 requirements. For example, there may be instances where it is desirable to expose two or more adjacent conductors 13 to provide an electrode 11 with increased electrical conductivity and increased mechanical strength.

If the conductor 13 is insulated, the step of exposing the conductor cuts and removes the insulation on the wire in addition to cutting and removing the corresponding portion of the outer polymer sheath 14 .

As shown in Figure 2e, the opening 34 formed in the outer polymer sheath 14 is substantially filled with a conductive adhesive 15 of the type discussed above, such as silver filled epoxy. The conductor 13 coated with the conductive adhesive 15 provides sufficient electrical conductivity to function as the electrode 11 . Such electrodes 11 have special application as sensing electrodes.

However, as shown in Figure 2f, the method preferably further comprises the step of covering the conductive adhesive 15 with a solvent containing one or more conductive materials. Types of suitable materials are discussed above. These materials can be applied in a variety of ways, such as spraying, electrostatic deposition, direct application such as by brushing or padding, and the like. Better results were obtained using pad printing with silver filled inks or palladium filled inks or palladium/silver inks 16 .

The electrode 11 formed by pad-printing the conductive adhesive 15 with the conductive ink 16 in this way has particular application as a sensing electrode. The method also includes the further step of catalyzing the pad printing ink 16 with an acidic palladium chloride solution to deposit a palladium coating on the silver of the electrodes.

A pad-printed coating of conductive adhesive 15 or ink 16 is overlaid with a platinum layer 17 to increase conductivity across the electrodes. The electrode 11 comprising the platinum layer 17 is suitable for ablation in addition to induction. Palladium 17 is applied to the electrode 11 by electroless plating, but could also be applied by electrodeposition techniques.

The final electrode 11 may also be coated with a layer of a material suitable for blocking metal ions from the electrode. The epoxy resin layer can be applied by pad printing. The epoxy prevents the migration of silver ions from the electrode 11 .

In Figure 4 of the accompanying drawings, another embodiment of the invention is depicted, wherein like reference numerals refer to like parts referring to previous figures unless otherwise indicated. In this embodiment, a plurality of circumferentially spaced openings are formed by cutting portions 32 (not shown in FIG. 4 but shown in FIG. 2d ) at circumferentially spaced intervals around the outer sheath 14. 34. Connect multiple electrical conductors 13. While FIG. 4 depicts the openings 34 as being longitudinally aligned, it should be appreciated that the openings 34 may be staggered relative to each other along the length of the outer sheath 14 .

Each opening 34 is filled with conductive adhesive 15 , and a layer of conductive material 16 is pad printed around the circumference of outer sheath 14 overlying the conductive adhesive 15 in each opening 34 . A layer 17 of biocompatible metal is applied on the layer 16 of electrically conductive material.

Once the metal layer 17 has been applied, laser cutting 19 is performed through the layers 16 and 17 to form a plurality of circumferentially spaced discrete electrodes 11 . It will be appreciated that one advantage of this embodiment of the invention is that three-dimensional sensing or ablation can be achieved. Furthermore, it is easier to deploy the catheter 10 since the position of the electrodes 11 of the catheter 10 relative to the part of the patient's body to be treated is not critical, since it is always possible to have at least one electrode 11 in contact with the tissue.

Referring now to Figure 5 of the drawings, another embodiment of the present invention is described. Again, referring to the previous figures, like reference numerals refer to like parts unless otherwise indicated.

In this embodiment, ring 60 is applied on layer 16 instead of layer 17 of each electrode 11 being pad printed. The ring 60 is secured in place on the outer sheath 14 across the layer 16 associated with the outer sheath 14 by a suitable securing technique, such as adhesive, crimping, press fit, or the like.

Measuring the temperature at the electrode 11 is useful especially in cases where the electrode 11 is used for ablation purposes. Accordingly, the electrical lead 10 comprises a thermocouple 20 (Fig. 6b) or other suitable temperature measuring means.

As shown in Figure 6a, in a variation comprising a thermocouple 20 comprising a first wire 21 made of copper and a second wire 22 made of constantan. The outer polymer sheath 14 is cut, eg by laser cutting, to expose the wires 21 and 22 . Conductive adhesive 15 is applied to the exposed wires, as shown in Figure 6b. The wire adhesive 15 brings the two wires 21 and 22 of the thermocouple 20 into electrical contact with each other, thereby providing a thermocouple junction 23 .

When the thermocouple 20 is formed in this manner and to ensure accurate temperature readings, the thermocouple 20 needs to be insulated from the associated electrode 11 as described in the following steps. As shown in Figure 6c, after the wires 21 and 22 of the thermocouple 20 are exposed and the conductive adhesive 15 has been applied to the exposed wires 21 and 22, the wires and adhesive are exposed to a salt (NaCl) solution And current flows from a constant voltage source 26 through the wires 21 and 22 of the thermocouple 20 . The resulting current flow through the binder 15 causes the metal in the binder to be converted to metal chloride. When the adhesive 15 is a silver-filled epoxy, the silver on the facing surface of the adhesive is converted to a relatively thin layer of silver chloride 25, which acts as an insulating layer, separating the thermoelectric The couple 20 is electrically insulated from the electrode 11 of the electrical lead 10 .

The adhesive 15 of the electrode 11 and the adhesive 15 of the thermocouple 20 are then pad printed with a silver filled ink 16 and a platinum layer 17 is optionally applied to the ink 16 as shown in FIG. 6d.

Electrical lead 10 may include a single thermocouple 20 or alternatively include multiple thermocouples. In the latter case, each electrode 11 formed on the electrical lead 10 may have a corresponding thermocouple 20 .

example

Cables were sourced from Microhelix, Portland, Oregon (Microhelix, Portland, Oregon). The cable was prepared by molding a PEBAX jacket over a polymer coated wire mandrel. A mixture of nylon/polyurethane insulated copper and constantan wires (0.125 mm each) were helically wound around a polymer coated wire mandrel with a controlled pitch/winding angle. The PEBAX sheath is then placed on the winding wire. The resulting cable is cut into segments and the mandrels are removed. The cable is then heat treated to secure the outer PEBAX sheath to the coiled wire.

Excimer laser cut windows are then cut on each line at predetermined locations. The precise position of the window is programmed into the laser. The outer PEBAX sheath on each wire was removed along with the wire's insulation without disturbing the underlying wires.

Openings created by removal of PEBAX and insulating areas were filled with silver-filled epoxy from Creative Materials using a pneumatic dispenser. The silver filled epoxy was cured at a temperature of about 140° followed by plasma treatment in an argon atmosphere for about 1 minute.

This silver filled epoxy area is then pad printed with silver filled ink. Plates with notches about the size and spacing of the desired electrodes were wiped with silver filled ink, leaving ink in the notches. The liner is then lowered onto the top of the plate along the length of the ink-filled well. The pad picks up the ink and is placed on the cable such that the ink pad corresponds to the epoxy area on the cable to deposit ink on the cable on the epoxy area. This step is repeated multiple times as the cable is rotated so that a series of bands are formed around the circumference of the cable.

The cable is then cured in an oven at approximately 140°C for up to 15 hours.

The tape of the cable is then further catalyzed with an acidic PdCl solution.

Finally, the cable was placed in a commercially available electroless Pt solution using hydrazine as a reducing agent at about 60°C for about 1 hour. A layer of palladium with a thickness of about 0.5 microns is formed on the strip to form the final strip electrode.

Referring to Figures 7a to 7e of the accompanying drawings, another embodiment of a method of manufacturing an electrical lead 10 is described. Referring to the previous figures, like reference numerals designate like parts unless otherwise indicated.

In this embodiment of the invention, electrodes 11 are formed at spaced apart intervals along one length of the elongate member 10a for electrical communication with underlying conductors 13 (not shown in Figures 7a to 7e).

The elongated member 10a is cut at a distal end 40 remote from one of the electrodes 11, as shown in Figure 7a of the accompanying drawings.

A layer of epoxy 42 is applied at the distal end 40 of the elongated member 10a to seal the distal end of the elongated member 10a and to insulate the ends of the conductors at the distal end 40 . Another bead 44 of epoxy is applied to layer 42 to form the desired dome-shaped terminal electrode 46 .

In a next step, as shown in FIG. 7d of the accompanying drawings, the shaped end 46 is coated with a conductive silver ink of the same composition as used in forming the electrode 11 . It will thus be appreciated that the terminal electrodes 46 are formed prior to the application of the platinum layer on the electrodes 11 .

Thus, once the shaped end 46 has been coated with silver ink, all of the electrode 11 and the end electrode 48 are coated with a layer of platinum 17, as shown in Figure 7e of the accompanying drawings. Again, the platinum layer 17 is applied by electroless plating.

Referring now to Figures 8 to 11 of the drawings, yet another method of making an electrical lead 10 is described. Again, referring to the previous figures, like reference numerals designate like parts unless otherwise indicated.

In this embodiment, the radiopaque material 50 is longitudinally aligned with each of at least some of the openings 34 once each opening 34 has been formed in the outer sheath 14 prior to forming the electrode 11 around the outer sheath 14 imposed.

In the case of the embodiment shown in FIGS. 8 and 9 of the drawings, the radio-opaque material 50 is applied in the form of a cuff 52 around a portion of the circumference of the outer sheath 14 .

The cuff 52 is disposed on the sheath 14 such that the cuff is at the same longitudinal position of the sheath 14 as its associated opening 34, but is disposed in diametrically opposite relation to the opening 34 such that the radiation opaque material 50 There is no electrical contact with the conductor 13 or the conductive adhesive 15 in the opening 34 .

The radiation opaque material 50 is applied by pad printing and comprises between 70% and 80% non-conductive material and 20% to 30% adhesive. The radio-opaque material is a radio-opaque ink from Creative Material, Inc., 141 Middlesex Road, Tyngsboro, MA, 01879, USA. The bonding portion of the radiopaque material is conventionally epoxy. The epoxy of the radiopaque material 50 is matched to the epoxy of the silver layer 16, which is advantageous for biocompatibility.

Once the radio-opaque material 50 is applied, a layer of conductive silver material 16 is pad printed over the radio-opaque material and adhesive 15 in the opening 34 . Afterwards, the platinum layer 17 is applied by electroless plating.

In the embodiment shown in FIGS. 10 and 11 of the drawings, instead of applying the radio-opaque material 50 as the cuff 52 , a groove 54 is formed in the outer sheath 14 in diametrical relationship to the opening 34 . It will be appreciated that the depth of this groove 54 is such that it does not expose any conductor 13 in the outer sheath 14 .

The radio-opaque material 50 is filled into the groove 54 . In this embodiment, the epoxy of the radiation opaque material is chosen to be the same epoxy used to form the conductive fill 15 of the opening 34 . Again, this is advantageous for biocompatibility purposes.

Groove 54 may be of any suitable shape. Thus, as shown in Figure 11a of the accompanying drawings, the groove 54 may be a longitudinally extending slit. Alternatively, as shown in Figures 11b and 11c of the accompanying drawings, the groove 54 may have a cross shape. As shown in Figure 1 Id of the accompanying drawings, the grooves may be circular grooves. It will be appreciated that any shape of groove may be used with equal advantage.

Once the recess 54 contains the radio-opaque material 50, silver ink 16 is applied by pad printing, followed by electroless plating of the electrode 11 to form a layer 17 of platinum.

It should be appreciated that the silver ink layer 16 or the platinum layer 17 need not extend over the radio-opaque material 52 or 54, as the case may be. All that is necessary is that the radiopaque material 52 or 54 be aligned longitudinally with its associated electrode 11 .

An advantage of this embodiment is that the radio-opaque regions are formed in alignment with the electrodes 11, allowing quick and precise placement of the electrodes 11 by a clinician viewing the position of the electrodes 11 on the fluoroscopic screen.

Those skilled in the art will recognize that many changes and/or modifications can be made to the methods described herein without departing from the spirit or scope of the broad description. The particular description is therefore to be considered in all respects as descriptive rather than restrictive.

These modifications and changes are included in the scope of the present invention as defined by the appended claims.

Claims (46)

1. A method for manufacturing an electrical lead having one or more electrodes, the method comprising: providing an elongate member having at least one polymer region and further having at least one electrical conductor extending along at least part of a length of the elongate member and housed within a wall of the elongate member; accessing a length of the at least one electrical conductor at at least one polymer region; and A conductive adhesive is applied to the length of the access at least one electrical conductor. 2. The method of claim 1, wherein the conductive adhesive comprises silver filled epoxy. 3. The method of claim 2, wherein at least some of the silver particles of the silver-filled epoxy are coated with platinum or palladium. 4. A method according to any one of the preceding claims, comprising applying at least one electrically conductive material to the electrically conductive adhesive. 5. The method of claim 1, comprising covering the conductive adhesive with a metal including platinum. 6. The method of claim 4, comprising covering the conductive material with a metal including platinum. 7. A method according to any one of claims 1 to 3, wherein the elongate member comprises a plurality of electrical conductors, and wherein the method comprises accessing a length of each of the plurality of electrical conductors, the plurality of electrical conductors bodies at circumferentially spaced intervals around the elongate member, the method further comprising applying a liner of conductive adhesive to the accessed length of each conductor. 8. The method of claim 7, comprising applying a layer of at least one conductive material to each pad of conductive adhesive. 9. A method as claimed in claim 7 or 8, comprising covering each pad of conductive adhesive with a metal layer comprising platinum or palladium. 10. The method of claim 9, wherein the pads of conductive adhesive are arranged in longitudinally aligned relationship about the circumference of the elongated member, and wherein the method includes applying a metal layer as a continuous layer around the circumference, and thereafter separating the layer into a plurality of electrically insulating segments arranged at circumferentially spaced intervals to form a plurality of discrete electrodes arranged around the circumference of said elongate member . 11. A method as claimed in claim 6 or claim 10 comprising applying a metal comprising platinum by mounting a ring on the elongate member and securing the ring in position. 12. A method according to any one of the preceding claims, comprising insulating the electrical contact of the electrical lead from the one or more electrodes by: access to said electrical contact; applying a conductive adhesive to the first electrical contact; and Electrochemically treating the conductive adhesive such that portions of the conductive adhesive are converted to non-conductive portions. 13. The method of claim 12, wherein electrically treating the conductive material comprises passing an electric current through the electrical contact in an ionic environment. 14. The method of claim 13, wherein the ionic environment comprises a salt (NaCl) solution to electrochemically convert metal in the conductive adhesive to metal chloride. 15. A method according to any one of claims 12 to 14, wherein the electrical contact is a contact of a thermocouple junction. 16. A method of electrically insulating a first electrical contact of an electrical conductor from a second electrical contact of said electrical conductor, the method comprising: access to the first electrical contact; applying a conductive adhesive to the first electrical contact; and Electrochemically treating the conductive adhesive such that portions of the conductive adhesive are converted to non-conductive portions. 17. The method of claim 16, wherein the electrochemical treatment includes the step of passing an electrical current through electrical contacts in an ionic environment. 18. The method of claim 17, wherein the ionic environment comprises a salt (NaCl) solution to electrochemically convert metal in the conductive adhesive to metal chloride. 19. A method as claimed in any one of claims 15 to 18, wherein the first electrical contact comprises a temperature sensing component. 20. The method of any one of claims 16 to 19, wherein the second electrical contact comprises an energy transfer electrode. 21. The method of claim 20, wherein the temperature sensing component comprises a thermocouple having a first wire made of copper and a second wire made of constantan. 22. A method of making an electrical conductor, the method comprising: providing an elongated member having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor terminating in electrical connection with a conductive region disposed outside of said elongated member; cutting the elongate member away from the conductive region; forming a non-conductive termination remote from the conductive region; and A conductive material is applied over the conductive regions and terminals to form terminal electrodes for the electrical leads. 23. A method of making an electrical conductor, the method comprising: providing an elongate member having a proximal end and a distal end, the elongate member having one or more polymer regions, and further having a plurality of electrical conductors along at least one length of the elongate member extending partially toward a distal end of the elongated member, the electrical conductor being housed within a wall of the elongated member; For each of at least some of the electrical conductors, a conductive region in electrical contact with its associated electrical conductor is formed by: accessing a length of each of at least some of the electrical conductors through the polymeric region of the elongated member, and applying a conductive adhesive to each of the accessed electrical conductors; applying a conductive material at an access point associated with each electrical conductor to form a plurality of conductive regions spaced longitudinally along the length of the elongated member; cutting the elongated member away from one of the conductive regions; applying a non-conductive termination remote from the one conductive region; and A conductive material is applied to bridge the conductive region and the terminal to form a terminal electrode of the elongated member. 24. A method as claimed in claim 22 or claim 23 comprising applying the termination in a liquid state. 25. The method of claim 24, comprising applying the terminal in two stages, a first layer being applied to seal the distal end of the elongated member, and a second layer being applied and shaped to provide the desired end electrode. shape. 26. A method as claimed in claim 22 or claim 23 comprising applying a solid state termination to the distal end of the elongate member. 27. A method as claimed in claim 22 or claim 23 comprising applying the conductive material in two stages. 28. The method of claim 27, comprising applying a first layer to the non-conductive terminal and the conductive region to bridge the conductive region and the terminal. 29. The method of claim 28, comprising covering the first layer with a conductive biocompatible material. 30. An electrical lead comprising: an elongated member having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor being in contact with the conductive region terminated in an electrical connection, the conductive region being disposed outside of said elongate member; a non-conductive terminal disposed away from the conductive region and at the distal end of the elongate member; and At least one layer of conductive material bridging the conductive region and the non-conductive terminal to form a terminal electrode of the conductive component. 31. The lead according to claim 30, wherein said terminal is fabricated from a non-conductive material comprising resin. 32. The lead according to claim 31, wherein said terminal is a synthetic resin. 33. A lead according to any one of claims 30 to 32, wherein said terminal is a solid element adhesively fixed to the distal end of said elongated member to seal said end and form said terminal electrode. desired shape. 34. A method of making an electrical conductor, the method comprising: An elongated member is provided having a proximal end and a distal end, at least one electrical conductor housed in the elongated member and extending from the proximal end to the distal end of the elongated member, the at least one electrical conductor being in contact with the conductive region terminated in the electrical connection of said conductive region being disposed outside said elongated member; forming an access point in said elongate member to provide access to said at least one electrical conductor; applying a radio-opaque material to a region of the elongated member in longitudinal alignment with, but not in electrical contact with, the access point; and A conductive region is formed by applying at least one layer of conductive material around the elongate member, in electrical contact with the conductor through the access point, and overlying the radiation opaque material. 35. The method of claim 34, comprising applying the radio-opaque material as a layer to an outer surface of the elongate member to form a cuff around the elongate member. 36. The method of claim 35, comprising positioning the cuff diametrically opposite the access point on the elongated member. 37. The method of claim 36, comprising applying the layer of conductive material on the cuff, the layer of conductive material comprising a first layer of conductive material overlaid with a second layer of biocompatible conductive material. 38. The method of claim 34, comprising inserting the radiopaque material into a groove formed in the elongate member at the diametrically opposite side of the access point. In the region of slender parts. 39. An electrical lead comprising: an elongate member having a proximal end and a distal end, at least one electrical conductor housed in the elongate member and extending from the proximal end to the distal end of the elongate member; access points formed in the walls of the elongate member at predetermined locations to provide access to the electrical conductors; a region of radiopaque material carried by the elongated member in a region of the elongated member longitudinally aligned with, but circumferentially spaced from, the access point; and At least one layer of electrically conductive material having at a predetermined location on the elongated member to provide electrical contact with the electrical conductor through the access point and overlying the radio-opaque material. 40. A lead as claimed in claim 39, wherein the access point is in the form of a transversely arranged slot in the wall of the elongated member, the slot being along the direction of winding of the electrical conductor. 41. A lead as claimed in claim 39 or claim 40, wherein the radio-opaque material comprises about 70% to 80% non-conductive material and about 20% to 30% adhesive material. 42. The lead of claim 41, wherein the adhesive material comprises epoxy. 43. A lead as claimed in claim 41 or 42, wherein the radio-opaque material is applied as a layer around a portion of the circumference of the elongate member. 44. The lead of claim 43, wherein the epoxy of the adhesive material of the radio-opaque material matches the epoxy of the layer of conductive material. 45. The lead of claim 42, wherein the radio-opaque material is received in a groove of the elongate member, the groove being disposed in a diametrically opposite position relative to the access point. 46. The lead of claim 45, wherein the epoxy of the radiopaque material is selected to be the same as the epoxy used in filling the access point.

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