Patent Publication Number: US-2011056729-A1

Title: Insulated conductive element having a substantially continuous barrier layer formed through continuous vapor deposition

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is related to commonly owned and co-pending U.S. Utility patent applications entitled “An Insulated Conductive Element Comprising Substantially Continuously Coated Sections Separated By Uncoated Gaps,” filed Sep. 9, 2009; “An Insulated Conductive Element Having A Substantially Continuous Barrier Layer Formed Via Relative Motion During Deposition,” filed Sep. 9, 2009; and “An Insulated Conductive Element Comprising Substantially Continuous Barrier Layer Formed Through Multiple Coatings,” filed Sep. 9, 2009. The content of these applications is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to coated conductive elements, and more particularly, to an insulated conductive element having a substantially continuous barrier layer formed through continuous vapor deposition. 
     2. Related Art 
     The use of medical devices to provide therapy to individuals for various medical conditions has become more widespread as the therapeutic benefits of such devices become more widely appreciated and accepted throughout the population. For example, hearing aids, implantable pacemakers, defibrillators, functional electrical stimulation devices, prosthetic hearing devices, organ assist and replacement devices, sensors, drug delivery devices and other medical devices, have successfully performed life saving, lifestyle enhancement or other therapeutic functions for many individuals. One common usage of medical devices is to treat an individual&#39;s hearing loss. 
     Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. In some cases, a person suffers from both types of hearing loss. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the cochlea are impeded, for example, by damage to the ossicles. Individuals suffering from conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As a result, individuals suffering from conductive hearing loss typically receive a hearing prosthesis that generates mechanical motion of the cochlea fluid. 
     In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. As such, many individuals suffering from sensorineural hearing loss are thus unable to derive suitable benefit from hearing prostheses that generate mechanical motion of the cochlea fluid. As a result, hearing prostheses that deliver electrical stimulation to nerve cells of the recipient&#39;s auditory system have been developed. Such electrically-stimulating hearing prostheses deliver electrical stimulation to nerve cells of the recipient&#39;s auditory system thereby providing the recipient with a hearing percept. Electrically-stimulating hearing prostheses include, for example, auditory brain stimulators and cochlear prostheses (commonly referred to as cochlear prosthetic devices, cochlear implants, cochlear devices, and the like; simply “cochlear implants” herein.) 
     Oftentimes sensorineural hearing loss is due to the absence or destruction of the cochlear hair cells which transduce acoustic signals into nerve impulses. Cochlear implants provide a recipient with a hearing percept by delivering electrical stimulation signals directly to the auditory nerve cells, thereby bypassing absent or defective hair cells that normally transduce acoustic vibrations into neural activity. Such devices generally use a stimulating assembly implanted in the cochlea so that the electrodes may differentially activate auditory neurons that normally encode differential pitches of sound. As is known in the art, a stimulating assembly comprises a plurality of electrode contacts each individually electrically connected to a stimulator unit via elongate conductive elements, such as wires. In practice, a coating is applied to the surface of the conductive elements for one or more of electrical and physical insulation, passivation, biocompatibility and immobilization of microscopic particles. 
     SUMMARY 
     In one aspect of the present invention, a continuous vapor deposition system for coating an elongate, uncoated conductive element with a substantially continuous barrier layer is provided. The system comprises: an internal deposition chamber configured to have a section of the conductive element extend there through; a vapor supply system connected to the internal deposition chamber configured to provide a barrier material to the internal deposition chamber, wherein the barrier material is deposited on the section of the conductive within the internal deposition chamber to form a substantially continuous barrier layer; and a guide system positioned adjacent to the first deposition chamber configured to maintain tension in the section of the conductive element in the internal deposition chamber to control movement of the conductive element through the internal deposition chamber. 
     In another aspect of the present invention, a method of coating an elongate, uncoated conductive element with a substantially continuous barrier layer with a continuous vapor deposition apparatus having an internal deposition chamber is provided. The method comprises: positioning a first section of the elongate conductive element in the internal deposition chamber, wherein the first section of the elongate conductive element extends through the chamber between opposing sections of a guide system positioned external to the chamber; depositing a barrier material on the section of the elongate conductive element in the deposition chamber; and moving the conductive element through the internal deposition chamber with the guide system during to ensure that the section of conductive element positioned in the internal deposition chamber is coated with the substantially continuous barrier material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention are described below with reference to the attached drawings, in which: 
         FIG. 1  is a simplified schematic view of a conventional vapor deposition apparatus; 
         FIG. 2A  is a perspective view of a conventional coating frame having a wire secured thereto with tape during a conventional chemical deposition process; 
         FIG. 2B  is a cross-sectional, expanded view of a section of the prior art coating frame and wire arrangement of  FIG. 2A ; 
         FIG. 2C  is a cross-sectional side view of two separate prior art coated wires removed from the coating frame of  FIGS. 2A and 2B ; 
         FIG. 3A  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 3B  is a perspective view of the coating frame of  FIG. 3A  having a wire wound there around, in accordance with embodiments of the present invention; 
         FIG. 3C  is a cross-sectional view of a coating frame rod of  FIGS. 3A and 3B  having a wire in contact therewith in accordance with embodiments of the present invention; 
         FIG. 3D  is a cross-sectional side view of a coated wire prior to removal from the coating frame, in accordance with embodiments of the present invention; 
         FIG. 3E  is a side view of a coated wire following removal of the wire from a coating frame in accordance with embodiments of the present invention; 
         FIG. 3F  is a cross-sectional side view of the coated wire of  FIG. 3E  taken along cross-sectional line  3 F- 3 F; 
         FIG. 4  is a schematic block diagram of a wire winding system that may be used to wind a wire around a coating frame, in accordance with embodiments of the present invention; 
         FIG. 5  is a flowchart illustrating the operations performed to form an elongate conductive element in accordance with embodiments of the present invention; 
         FIG. 6A  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 6B  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 6C  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 6D  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 6E  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 7A  is a perspective view of a section of a coating frame rod in accordance with embodiments of the present invention; 
         FIG. 7B  is a perspective view of a section of a coating frame rod in accordance with embodiments of the present invention; 
         FIG. 7C  is a perspective view of a section of a coating frame rod in accordance with embodiments of the present invention; 
         FIG. 7D  is a perspective view of a section of a coating frame rod in accordance with embodiments of the present invention; 
         FIG. 8  is a flowchart illustrating the operations performed to form an elongate conductive element in accordance with embodiments of the present invention; 
         FIG. 9A  is a perspective view of a coating frame connected to a coating frame drive system in accordance with embodiments of the present invention; 
         FIG. 9B  is a side view of the coating frame of  FIG. 9A  connected to a spring in accordance with embodiments of the present invention; 
         FIG. 9C  is a side view of a coating frame rod and a pair of support arms of  FIG. 9A  in accordance with embodiments of the present invention; 
         FIG. 10  is cut away view of a deposition chamber having the coating frame of  FIG. 9A  therein, in accordance with embodiments of the present invention; 
         FIG. 11  is a top view of an expandable coating frame in accordance with embodiments of the present invention; 
         FIG. 12  is partial perspective view of a portion of a coating frame having recessed wire support regions, in accordance with embodiments of the present invention; 
         FIG. 13A  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 13B  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 13C  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 13D  is a perspective view of a coating frame in accordance with embodiments of the present invention; 
         FIG. 14  is a side view of a coating frame rod in accordance with embodiments of the present invention; 
         FIG. 15A  is a perspective view of an alternative coating frame comprising a plurality of independently rotatable members; 
         FIG. 15B  is a top view of a rotatable member of in accordance with embodiments of the present invention; 
         FIG. 15C  is a top view of a rotatable member of in accordance with embodiments of the present invention; 
         FIG. 16  is a schematic block diagram of a continuous vapor deposition apparatus, in accordance with embodiments of the present invention; 
         FIG. 17  is a schematic diagram illustrating further details of the continuous chemical deposition apparatus of  FIG. 16 , in accordance with embodiments of the present invention; 
         FIG. 18A  is a detailed schematic diagram of one embodiment of the conductive element supply system of the continuous vapor deposition apparatus of  FIG. 17 ; 
         FIG. 18B  is a detailed schematic diagram of one embodiment of the conductive element collection system of the continuous vapor deposition apparatus of  FIG. 17 ; 
         FIG. 19A  is a cross-sectional view of an internal deposition chamber having a wire extending there through, in accordance with embodiments of the present invention; 
         FIG. 19B  is a cross-sectional view of an internal deposition chamber having a wire extending there through, in accordance with embodiments of the present invention; 
         FIG. 19C  is a cross-sectional view of an internal deposition chamber having a wire extending there through, in accordance with embodiments of the present invention; 
         FIG. 19D  is a cross-sectional view of an internal deposition chamber having a wire extending there through, in accordance with embodiments of the present invention; 
         FIG. 19E  is a side view of one embodiment of a rod and support arm used in embodiments of the continuous vapor deposition apparatus of  FIG. 16 ; 
         FIG. 20  is schematic view of further embodiments of a continuous vapor deposition apparatus, in accordance with embodiments of the present invention; 
         FIG. 21  is a flowchart illustrating the operations performed to form an elongate conductive element using a continuous vapor deposition apparatus in accordance with embodiments of the present invention; 
         FIG. 22A  is a flowchart illustrating the operations performed to form an elongate conductive element using movement of a wire with respect to a coating frame in accordance with embodiments of the present invention; 
         FIG. 22B  is a flowchart illustrating the operations performed to form an elongate conductive element using movement of a wire from a first to a second coating frame in accordance with embodiments of the present invention; 
         FIG. 23A  is a cross-sectional view of a wire coated with an intermediate layer in accordance with embodiments of the present invention; 
         FIG. 23B  is a side view of coated wire coated with a barrier layer in accordance with embodiments of the present invention; 
         FIG. 24A  is a perspective view of a wire guide system for transferring a partially coated wire from a first coating frame to a second coating frame; and 
         FIG. 24B  is a perspective view of a wire guide system for transferring a partially coated wire from a first coating frame to a second coating frame. 
     
    
    
     DETAILED DESCRIPTION 
     Conventionally, vapor deposition commonly refers to a process in which a material in a vapor state is condensed to form a solid material. Vapor deposition, which is generally divided into two broad categories known as physical vapor deposition (PVD) and chemical vapor deposition (CVD), is often used to form coatings on objects. Such coatings are provided to, for example, alter the mechanical, electrical, thermal, optical, corrosion resistance, and/or wear properties of the objects. 
     As described in detail below, embodiments of the present invention are generally directed to using vapor deposition to coat elongate conductive elements with a protective conformal barrier layer. The barrier layer may be applied to the conductive elements for a variety of reasons including providing electrical insulation, biocompatibility, immobilization of microscopic particles, and ensuring that the conductive elements are passive, as well as providing physical isolation of the conductive elements from moisture, chemicals, and other substances. As used herein, a conductive element having a barrier layer in accordance with embodiments of the present invention disposed on the surface thereof is referred to as an insulated conductive element. 
     In certain embodiments, the barrier layer is a polymeric material. In one particular embodiment, the barrier layer is parylene. Parylene is the generic name for a variety of vapor deposited poly-para-xylylenes. These materials form highly-crystalline polymers that may be applied as conformal coatings and films. Parylene, unlike other polymeric materials, is not manufactured or sold as a polymer. Rather it is produced by vapor-phase deposition and polymerization of para-xylylene or its derivatives. 
     There are a variety of derivatives and isomers of parylene. The most common variants include Parylene C, Parylene N, and Parylene D. It would be appreciated that other variants of parylene are also commercially available. 
       FIG. 1  is a simplified schematic diagram of a conventional vapor deposition apparatus  150 . Vapor deposition apparatus  150  comprises a vapor supply system  106  configured to supply the necessary vapor material to a deposition chamber  104 . In the system illustrated in  FIG. 1 , vapor supply system  106  includes a vaporization chamber  100  that vaporizes a quantity of a dimer inserted therein via closable aperture  110 . As is known in the art, a dimer is a chemical or biological substance consisting of a plurality of bonded monomers. 
     Vapor supply system  106  further comprises a pyrolysis chamber  102  connected to vaporization chamber  100  by supply line  154 . Line  154  includes a valve  112  that controls the flow of vaporized dimer from vaporization chamber  100  to pyrolysis chamber  102 . Once transferred to pyrolysis chamber  102 , the vaporized dimer is pyrolized at temperatures of approximately 400 to 750 degrees Celsius to form a desired monomer vapor. The monomer vapor is transferred from pyrolysis chamber  102  via supply line  156  into deposition chamber  104 . Supply line  156  also includes a control valve  114  that controls the flow of the vapor into deposition chamber  104 . 
     Following deposition and condensation, residual vapor is removed from deposition chamber  104  via exit line  158 . Exit line  158  is connected to a cold trap  118  that serves to rapidly condense and polymerize any residual vapors. Vacuum pump  108  is connected to cold trap  118  via vacuum line  152  and maintains continual negative pressure within deposition chamber  104  and cold trap  118 . 
     Conventional vapor deposition systems and apparatuses are known in the art. As such, further details of the vapor deposition apparatus  150  will not be provided herein. 
     Also as known in the art, a vapor deposition apparatus may be used to provide coatings on various different types of objects, such as components of an implantable medical device. As an example, one type of medical device which may advantageously utilize vapor deposition is a cochlear implant. As is known in the art, a cochlear implant comprises a stimulating electrode assembly implantable in a recipient&#39;s cochlea. The stimulating electrode assembly comprises a plurality of electrode contacts individually electrically connected to a stimulator unit via elongate conductive elements, such as wires. The wires connecting the electrode contacts to the stimulator unit are electrically insulated so that the wires may be bundled together for implantation without electrical interference. 
     In certain circumstances, a vapor deposition process may be used to provide electrically insulated wires for connecting electrodes to a stimulator unit during manufacturing of a cochlear implant.  FIGS. 2A-2B  illustrate a conventional vapor deposition process for production of coated wires, while  FIG. 2C  illustrate two separate wires obtained as the result of the conventional process of  FIGS. 2A and 2B . 
     During the conventional wire coating process of  FIGS. 2A and 2B , a wire  222  is wound around opposing sides of a rectangular coating frame  220 . As shown in  FIG. 2A , coating frame  220  comprises four bars or rods that are welded together to form the rectangular shape. Opposing sides of coating frame  220  have double-sided tape  224  secured to the surface thereof. 
       FIG. 2B  is an expanded view of the section of  FIG. 2A  labeled as  FIG. 2B . As shown in  FIG. 2B , as wire  222  is wound around coating frame  220 , the wire is positioned in contact with an adhesive surface of tape  224 . Thus, tape  224  affixes wire  222  to the opposing sides of coating frame  220  thereby preventing any movement of wire  222 . 
     After wire  222  is secured to coating frame  220 , the coating frame may be positioned in a deposition chamber, such as deposition chamber  104  of vapor deposition apparatus  150 , for deposition of the coating. Following deposition of the coating, coating frame  220  is removed from the deposition chamber and discrete wires are formed from the coated portions of wire  222 . More specifically, because wire  222  is secured to coating frame  220  using tape  224 , the wire can not be removed from the tape without damaging the wire. Furthermore, because the coating extends across the tape/wire boundary  225 , removal of the tape also removes portions of the coating on wire  222 , or damages those sections of the wire that are adhered to the tape. Therefore, only those portions of the wire that are not in contact with tape  224  are utilized. This necessitates that discrete, physically separate sections of coated wired  222 , shown in  FIG. 2C , be cut from the portions of wire  222  extending between the opposing sides of coating frame  220 . In certain circumstances, the wound wire  222  is cut at or near each tape/wire boundary  225 , and each turn of the wound wire forms two separate coated sections. 
     As shown in the cross-sectional views of  FIG. 2C , the separate sections of coated wire  222  have a conductive core substantially surrounded by a layer of coating  226 . Discrete sections of coated wires produced using the above process may be used in the production of conventional cochlear implants and other medical devices. 
     Embodiments of the present invention are generally directed to producing a contiguous length of a coated conductive element, referred to herein as an insulated conductive element comprising substantially continuously coated sections separated by uncoated gaps. The uncoated gaps are formed at substantially predictable or determinable locations, and have a length that is substantially small relative to the lengths of the coated sections. Certain embodiments of the present invention are directed to using vapor deposition to form the elongate insulated conductive element.  FIGS. 3A and 3B  illustrate a coating frame  330  that may be used to form such an insulated conductive element. Coating frame  330  may be formed from any material which has sufficient strength to maintain a desired shaped when subjected to the operations described below. In specific embodiments, coating frame  330  is formed from stainless steel. 
     The elongate conductive elements that may be utilized in embodiments of the present invention include, but are not limited to, single or multi-strand wires, conductive ribbons, shim or carbon nanotube (CNT) yarns, etc. In certain embodiments, the elongate conductive elements have a desired amount of malleability. Furthermore, elongate conductive elements utilized in embodiments of the present invention may have varying lengths. In embodiments of the present invention, the conductive element has a length of approximately 1-100 meters, while in specific embodiments the conductive element has a length of approximately 5-10 meters. It would be appreciated that other lengths may also be utilized. For ease of illustration, embodiments of the present invention will be primarily described herein with reference to a single strand wire  332 . 
     In the embodiments of  FIGS. 3A and 3B , coating frame  330  comprises two substantially parallel bases  320 , and a plurality of substantially parallel, spaced rods  334  extending between the bases. In the illustrative embodiments of  FIGS. 3A and 3B , bases  320  each are hexagonal in shape and comprise six members  318  joined to each other to form vertices  341 . Rods  334  extend between opposing vertices  341  of bases  320 . Therefore, the distance between adjacent rods  334 , illustrated by dimension line  301  in  FIG. 3A , is equal to the length of the base member  318  positioned between adjacent vertices  341  to which the adjacent rods  334  are attached. 
     As shown in  FIG. 3B , uncoated wire  332  is wound around rods  334  into a plurality of turns  331 . As described in greater detail below, wire  332  is wound under tension such that the wound wire does not move relative to coating frame  330  and remains substantially stationary during subsequent deposition. 
       FIG. 3C  is a top view of a section of wire  332  positioned in contact with one of the rods  334 . As shown, each turn  331  contacts each rod  334  for a length, referred to herein as the wire/rod contact length  353 , or simply contact length  353 . Because rods  334  have a cylindrical shape, contact length  353  between rod  334  and wire  332  follows an arc defined by angle  316  that corresponds to a portion of the surface of rod  334 . As described below, contact length  353  between rod  334  and wire  332  may vary depending on, for example, the shape of rod  334 . 
     It would be appreciated that the contact length between rod  334  and wire  332  may also vary depending on, for example, the number of rods  334  within coating frame  330  that wire is wound around, the distance between rods  334 , etc. Regardless of the number of rods  334 , etc., the contact length between wire  332  and rods  334  remains substantially small relative to the distance between adjacent rods  334  of coating frame  332 . 
     As noted above, after wire  322  is securely wound around coating frame  320  and secured thereto via the wire tension, coating frame  330  is positioned in a deposition chamber, such as deposition chamber  104  of vapor deposition apparatus  150  ( FIG. 1 ), for deposition of a barrier material on wire  332 .  FIG. 3D  is a side view of section of rod  334  and wire  332  illustrated in  FIG. 3C . In the embodiments of  FIG. 3D , wire  332  and barrier layer  336  are shown in cross-section. For ease of illustration, in the embodiments of  FIG. 3D  wire  332  and barrier layer  336  are not shown to scale. 
     It would be appreciated that the thickness of barrier layer  336  may vary. In certain embodiments, wire  332  may have a diameter of approximately 5-100 microns, and barrier layer  336  may have a thickness of approximately 3-10 microns. In specific embodiments, wire may have a diameter of 10-30 microns, and barrier layer  336  may have a thickness of approximately 5-7 microns. 
     As shown in  FIG. 3D , the deposition of the barrier material on wire  332  forms a barrier layer  336  substantially covering the surface of wire  332  that is not in direct contact with rod  334 . Because wire  332  is wound under tension, and no additional fixation elements are required, the release of the tension permits the unwinding of wire  332  from coating frame  332  as a unitary, contiguous element, referred to as insulated conductive element  360 . A side view of a section of insulated conductive element  360  is shown in  FIG. 3E , while a cross-sectional view of insulated conductive element  360  taken along cross-sectional line  3 F- 3 F of  FIG. 3E  is shown in  FIG. 3F . 
     As shown in  FIG. 3E , unwound insulated conductive element  360  comprises a plurality of coated sections  339  separated by uncoated gaps  338 . For ease of illustration, portions of each coated section  339  have been omitted from  FIG. 3F . The length of coated sections  339  are approximately equal to the distance  301  between adjacent rods  334 , while the length of uncoated gaps are approximately equal to the contact length between a rod  334  and wire  332 , described above with reference to  FIG. 3C . It would be appreciated that these lengths may vary, but the length of uncoated gaps  339  are substantially smaller than the length of coated sections  339 . 
     Also as noted above, the length of coated sections  339  generally correspond to the distance  301  between adjacent rods  334 . Therefore, gaps  338  are generally formed at predictable or determinable locations. Because the gaps  338  are formed at predictable or determinable locations, the gaps may be managed during subsequent processing. 
     It would be appreciated that the embodiments of  FIGS. 3A-3F  have not been shown to scale. It would also be appreciated that various sizes and shapes of conductive elements, thicknesses of barrier layer  336 , as well as various gaps  338  and coated sections  339  may be implemented in embodiments of the present invention. In one exemplary embodiment, a wire having a 25 micron diameter is coated with a barrier layer having an average thickness that is approximately 3-10 microns. In such embodiments, uncoated gaps may have a length of approximately 2-5 millimeters, and the coated sections may have a length of 200-300 millimeters. In specific embodiments, uncoated gaps may have a length of 2.5 millimeters, and coated sections may have a length of approximately 250 millimeters. 
     As noted above, wire  332  is wound around coating frame  330  under tension. In certain embodiments, wire  332  may be manually wound around coating frame  332 . As used herein, manual winding of wire  332  includes the use of one or tools (jigging, etc.) that facilitate the winding. In alternative embodiments, wire  332  may be wound around coating frame  330  using a winding system, such as winding system  490  illustrated in  FIG. 4 . 
     As shown in  FIG. 4 , winding system  490  comprises a pitch control system  478 , and a tensioner  480  that transfer wire  332  from a spool  476  to coating frame  330 . It would be appreciated that winding system  490  may also be used to transfer wire  332  from coating frame  330  to spool  476 . 
     In the embodiments of  FIG. 4 , pitch control system  478  converts the pitch of the wire from spool  476  to a pitch for winding on to coating frame  330 . Tensioner  480  controls the tension of wire  332  as it is wound around coating frame  330 . Tensioner  330  is configured to ensure that the wire  332  is not placed under a tensile force that would damage or break wire  332 , but with a sufficient tension that the wire remains substantially stationary during deposition. 
     As shown in  FIG. 4 , winding system  490  includes system drive components  474 , comprising spool drive  474 A, pitch control  474 B and coating frame drive  474 C, that electrically and/or mechanically control(s) the movement or operation of spool  476 , pitch control system  478  and coating frame  330 , respectively. Spool drive  474 A, pitch control drive  474 B and coating frame drive  474 C receive control signals from control module  470 . Tensioner  480  mechanical controls the tension of wire  332  and receives control signals directly from control module  470 . As shown, control module  470  includes a user interface  472 . 
       FIG. 5  is a flowchart illustrating a process  500  for coating an elongate, uncoated conductive element with a barrier layer to form an insulated conductive element of the present invention. The insulated conductive element comprises substantially continuously coated elongate sections separated by uncoated gaps which are substantially small relative to the lengths of the coated sections. 
     Process  500  begins at block  502  at which an uncoated elongate conductive element is wound, under tension, around a plurality of spaced, substantially parallel rods such that each turn of the conductive element contacts at least two rods of the coating frame. Process  500  continues at block  504  at which a barrier material is deposited on the conductive element to form a barrier layer on the surfaces of the conductive element which are not in contact with the rods. At block  506 , the conductive element is unwound from the coating frame. The surfaces of the conductive element that were in contact with the rods during deposition form the uncoated gaps, while the sections of the conductive element between the rods form the coated sections of the insulated conductive element. 
     As described above, the embodiments of  FIGS. 3A-3F  were primarily been described with reference to a coating frame  330  comprising a plurality of spaced rods  334  extending between substantially parallel bases  320 . It would be appreciated that alternative coating frames may also be implemented in embodiments of the present invention.  FIGS. 6A-6E  illustrate specific alternative embodiments. 
     In the embodiments of  FIG. 6A , coating frame  630 A has opposing bases  620 A each comprising a single elongate member. Extending between opposing edges of bases  620 A are two substantially parallel rods  634 . Thus, in this embodiment coating frame  630 A has a substantially planar shape. 
       FIG. 6B  illustrates another embodiment of the coating frame of the present invention in which a coating frame  630 B has opposing bases  620 B each comprising three elongate members arranged to have a triangular configuration. Extending between the opposing vertices  641  of bases  620 B are three substantially parallel rods  634 . 
     Furthermore, in the embodiments of  FIG. 6C , a coating frame  630 C has opposing bases  620 C each comprising four elongate members arranged in a rectangular configuration. Extending between the opposing vertices  643  of bases  620 C are four substantially parallel rods  634 . 
       FIG. 6D  illustrates further embodiments in which coating frame  630 D has opposing bases  620 D each comprising five elongate members arranged in a pentagonal configuration. Extending between the opposing vertices  645  of bases  620 D are five substantially parallel rods  634 . 
     In the embodiments of  FIG. 6E , coating frame  630 E has opposing bases  620 E each comprising eight elongate members arranged in an octagonal configuration. Extending between the opposing vertices  647  of bases  620 E are eight substantially parallel rods  634 . 
     As noted,  FIGS. 6A-6E  illustrate embodiments in which a coating frame  630  comprises two, three, four, five and eight substantially parallel rods  634 , respectively. It would be appreciated that greater number of rods arranged in a variety of positions may be implemented in embodiments of the present invention. Thus, the above embodiments would be considered illustrative and do not limit the present invention. It would also be appreciated that bases  620  are not limited to the use of arranged elongated members and may be formed, for example, from a planar element such as a sheet of metal, plastic, etc. 
     The above aspects of the present invention have been generally illustrated with reference to tubular rods having a generally circular cross-sectional shape. Rods having alternative cross-section shapes may also be utilized to maintain the strength of the rod while minimizing the contact length between a wire and a rod. As described above, minimizing the contact length between a wire and a rod minimizes the gaps that are formed in the barrier layer.  FIGS. 7A-7D  illustrate specific alternative rods having different cross-sectional shapes. Specifically,  FIG. 7A  illustrates a rod  734 A having an oval cross-sectional shape. In such embodiments, rod  734 A would be positioned within a coating frame such that a wire wound there around is in contact with one of the ends  735  positioned on the long axis of the oval. 
       FIG. 7B  illustrates another alternative embodiment in which a rod  734 B has a generally triangular cross-sectional shape. In such embodiments, rod  734 B is positioned in a coating frame such that the wire contacts rod  734 B at the rounded apex  737  of the rod. Apex  737  has a radius of curvature that ensures that apex  737  does not have sharp edges that may potentially damage a wire in contact therewith. 
       FIG. 7C  illustrates a still further embodiment in which rod  734 C has a triangular portion  744  extending from an oblong portion  742 . Rod  734 C is positioned in a coating frame such that the wire contacts rod  734 C at the rounded apex  737  of triangular portion  744 . 
       FIG. 7D  illustrates a yet another embodiments in rod  734 D has an undulating surface  746  comprising a plurality of rounded projections  748 . When positioned within a coating frame, a wound wire contacts one or more rounded projections  748 . As noted above, embodiments of the present invention are directed to forming an insulated conductive element comprising substantially continuously coated elongate sections separated by uncoated gaps which are substantially small relative to the lengths of the coated sections. In the embodiments of  FIG. 7D , when the wire contacts two or more rounded projections  748 , the gap extends between the locations where the wire contacts the first rounded projection  748 , and the point where the wire contacts the last rounded projection  748  before extending to a subsequent rod. Because the wire is separated from rod  734 D between rounded projections, sections of coating may be formed within the gap. As used herein, a gap having sections of coating therein, such as the gaps formed using rod  734 D, is referred to as an uncoated gap. 
     As noted, the above embodiments of the present invention are generally directed to forming an insulated conductive element having a barrier layer comprising substantially continuously coated sections separated by uncoated gaps. The uncoated gaps have a length that is substantially small relative to the lengths of the coated sections. In certain above embodiments of the present invention, the uncoated gaps are generally disposed at known lengths, resulting in coated sections of known length. Furthermore, as used herein, a substantially continuous section refers to a continuous coating applied to those surfaces not in contact with a coating frame that may include minor imperfections resulting from the variability of a vapor deposition process or subsequent usage. 
     Further embodiments of the present invention described below are generally directed to forming an insulated conductive element having a substantially continuous barrier layer extending the length thereof. Similar to the embodiments described above, a substantially continuous barrier layer refers to a continuous coating applied to the length of the conductive element that may include minor imperfections resulting from the variability of a vapor deposition process or subsequent usage. 
       FIG. 8  illustrates a first method  800  of coating an elongate, uncoated conductive element with a substantially continuous barrier layer. The method begins at block  802  at which an uncoated conductive element is wound around a coating frame. The coating frame comprises a plurality of spaced supports, and the conductive element is wound around the coating frame such that sections of the conductive element are positioned in contact with the supports. 
     The method continues at block  804  at which a barrier material is deposited on the conductive element. At block  806 , during deposition of the barrier material, the relative position of the conductive element to the coating frame is adjusted so that substantially all sections of the conductive element are physically separated from the supports for a time that is sufficient to form the substantially continuous barrier layer. In other words, at least one of the conductive element and the coating frame are moved relative to another during deposition. This relative movement results in each section of the conductive element being exposed for coating with the barrier material. At block  808 , the insulated conductive element is unwound from the coating frame. 
       FIGS. 9A-15  illustrate various apparatus that may be employed to move a conductive element relative to a coating frame during the method of  FIG. 8 . For ease of description,  FIGS. 9A-15  will be described with reference to a conductive element in the form of a single strand wire. It would be appreciated that other types of conductive elements such as multi-strand wires, conductive ribbons, shim or carbon nano tube (CNT) yarns, etc. may also be utilized in these embodiments of the present invention. 
       FIG. 9A  is perspective view of a coating frame  930  that may be implemented in embodiments of the present invention. As shown, coating frame  930  comprises opposing bases  920  having substantially parallel rods  934  extending there between. Extending from rods  934  are a plurality of elongate, spaced radial support arms  938 . A wire  932  may be loosely wound around coating frame  930  such that the wire is supported by the elongate surface of support arms  938 . 
     As noted above, a barrier layer is deposited on wire  932  to form an insulated conductive element. The barrier layer may be deposited on wire  932  through the use of a vapor deposition apparatus, such as apparatus  150  of  FIG. 1 .  FIG. 9A  illustrates specific embodiments of a coating frame  930  that, once positioned in a deposition chamber such a deposition chamber  104 , is connected to a coating frame drive system  946  via a coupling member  944 . In the embodiments of  FIG. 9A , coating frame drive system  946  comprises a motor  940  that rotates coupling member  944  and coating frame  930  during the coating process. In certain embodiments, coating frame drive system  946  also comprises an offset cam  942 . Offset cam  942  produces a non-circular rotation of member  944  that causes vibration of coating frame  930  during rotation. Because wire  932  is loosely wound around coating frame  930 , the vibration induced by offset cam  942  causes movement of the wire relative to the coating frame. More specifically, as a result of the vibration, substantially all sections of wire  932  are physically separated from the supports for a time that is sufficient to form the substantially continuous barrier layer. In other words, the vibration results in each section of wire  932  being exposed for coating with the barrier material. Furthermore, because the vibration is random, a generally uniform barrier layer is formed on the wire. 
     As noted above, coating frame  930  comprises a plurality of support arms  938  extending from rods  934 . Each support arm  938  is separated from an adjacent support arm  938  by a horizontal distance  982 , and a vertical distance  980 . Due to the continual vertical change between adjacent support arms  938 , the wound wire  932  follows an inclined helical path around coating frame  930 . The sloped pathway followed by wire  932  between adjacent support arms  938  is referred to as pitch or slope of the wire. 
     When coating wire  932 , the turns of the wire remain physically separate from one another during deposition. Therefore, the pitch of wire  932  versus the number of supports arms  938  is controlled to reduce the probability of the adjacent turns coming into contact with each other during deposition. The pitch of the wire (that is, the pitch between adjacent supports) is also a factor to ensure that there is sufficient spacing for winding the wire, cleaning of the coating frame after deposition, etc. Furthermore, support arms  938  having a length that, when wire  932  is positioned thereon, is sufficiently large that vibration of coating frame  930  likely does not cause wire  930  to contact rods  934 . For example, in certain embodiments, to form a barrier layer having a thickness of 5-7 microns on a 25 micron wire, a support arm of 25 mm length is used. In such embodiments, wire  932  is positioned approximately 10 mm from rod  934 . The 15 mm extension of the support arm from the position of wire  932  ensures that wire  932  does entirely separate from the support arm as a result of the vibration. 
     As noted above, in the embodiments of  FIG. 9A , coating frame  930  is coupled to a coating frame drive system  946  that causes vibration of coating frame  930 , thereby resulting in movement of wire  932  relative to coating frame  930 . In the embodiments of  FIG. 9B , once positioned in a deposition chamber, coating frame  930  is coupled to a spring  950  that facilitates vibration of coating frame  930 . In certain embodiments, spring  950  may be driven by a motor to induce the vibration. In alternative embodiments, spring  950  transfers and/or amplifies inherent vibration of the deposition apparatus to coating frame  930 . Alternatively, the inherent vibration in the deposition apparatus could be increased by removing some of the existing dampening elements, or altering the location of the vacuum pump so that vibration of the pump vibrates the chamber. 
       FIG. 9C  is a side view of two support arms  938  extending from a rod  934 . In this illustrative embodiment, support arms each extend from rod  934  at a downward angle  990 . Downward angle  990 , which is measured with respect to a horizontal axis  950  extending through rod  934  at the base of each support arm  938 , helps to prevent wire  930  from migrating towards rod  934  as a result of vibration. It would be appreciated that angle  990  varies in alternative embodiments. 
     It would be appreciated that various configurations for coating frame  930  are within the scope of the present invention. In one exemplary configuration, a coating frame has rods of 400 mm in length. Each rod includes support arms of 25 mm length, extending from the rod at a downward angle of 30 degrees. With a spacing of 3.5 mm between the distal end of an upper support arm and the base of a lower support arm, a total of 20 supports arms may be provided on each rod. Using these exemplary dimensions, the coating frame may support approximately 25 m of wire. It would be appreciated that the length of supported wire may be increased by decreasing the downward angle of the support arms, decreasing vertical spacing between support arms, increasing the rod height, etc. For example, a 400 mm rod having support arms of 2.5 mm in length at an angle of 0 degrees, and 0.5 mm spacing and a 3 mm wire pitch may support approximately 160 m of wire. 
       FIG. 10  is cut-away view of a deposition chamber  1004  having an embodiment of coating frame  930  described above positioned therein. In these embodiments, coating frame  930  is connected to a base plate  1052 . Similar to the embodiments of  FIG. 9A , base plate  1052  is connected to a coating frame drive system  946  positioned outside of chamber  1004  via coupling member  944 . As described above, motor  940  rotates coating frame  930 , and offset cam  942  induces vibration of the coating frame during the rotation. 
       FIGS. 9A-10A  have been described with reference to support arms  938  having a generally cylindrical shape terminating in a distal tip. It would be appreciated that other shaped support arms may be used in alternative embodiments of the present invention. For example, a support arm of the present invention may have any of the cross-sectional shapes described above with reference to  FIGS. 7A-7D . 
     Furthermore,  FIGS. 9A-10  illustrate embodiments of the present invention using a particular coating frame  930 .  FIGS. 11-15C  illustrate additional coating frames that may be implemented in embodiments of the present invention. 
       FIG. 11  is a top view of one alternative coating frame, referred to as expandable coating frame  1130 . As shown in  FIG. 11 , coating frame  1130  comprises rods  1160  attached to an expander  1162  which allows the rods to move from a collapsed position to an open or expanded position. When expander  1162  is in the open position, shown in  FIG. 11 , wire  1132  is wound in tension around coating frame  1130  so that the wire is positioned adjacent to support arms  1138  and expander rods  1160 . 
     As noted,  FIG. 11  is a top view of expandable coating frame  1130 . As such, wire  1132  is shown passing below the illustrated support arms  1138 , and the wire is supported by arms  1132  that are not visible in  FIG. 11  following removal of expander  1162 . 
     Once winding of wire  1132  is completed, expander  1162  is collapsed in towards the center allowing wire  1132  reducing or relieving the tension in the wire, and expander may be removed. That is, wire  1132  is then loosely wound around collapsed coating frame  1132  and rather than being held tightly against rods  1160 , wire  1138  is spaced from rods  1160 . In this position, wire  1132  is free to move relative to coating frame  1130  during deposition. 
       FIG. 12  is a partial perspective view of an alternative coating frame, illustrated at as coating frame  1230 . In this embodiment, coating frame  1230  comprises a cylindrical member having a recess  1266  formed therein. Recess  1266  spirals about the circumference of coating frame  1230 , and in this illustrative embodiment, has an undulating or wavy surface  1264 . A wire  1232  is loosely wound around coating frame  1230  and is supported by undulating surface  1264 . Similar to the embodiments described above, coating frame  1230  is vibrated during deposition so that wire  1232  moves with respect to coating frame  1230 . Furthermore, because only discrete sections of wire  1232  are in contact with undulating surface  1264  at any time, movement of wire  1232  with respect to coating frame  1230  produces a substantially continuous barrier layer on the surface of the wire. 
       FIG. 13A  is a perspective view of another coating frame, illustrated as coating frame  1330 A. Coating frame  1330 A comprises opposing bases  1320 , and a plurality of substantially parallel rods  1334  extending between the bases. In the illustrative embodiments of  FIG. 13A , coating frame  1330 A is positionable horizontally in a deposition chamber. That is, rods  1334  are configured to be positioned parallel to the bottom of the deposition chamber. In such embodiments, a vapor deposition apparatus having a horizontal deposition chamber may be utilized. 
     During deposition, coating frame  1330 A and wire  1332  both rotate with respect to the deposition chamber. However, wire  1332  is wound around rods  1334  under a tension that causes coating frame  1330 A to rotate at a speed that different than that of wire  1332 . Therefore, during rotation, coating frame  1330 A moves relative to wire  1332 . Because coating frame  1330 A moves relative to wire  1332  during deposition, sections of wire  1332  that are in contact with rods  1334  become physically separated from the rod. Those sections remain separated from the rod for a period of time that is sufficient to coat the sections with a desired thickness of barrier material. Thus, a substantially continuous barrier layer is formed on wire  1332 . 
     In alternative embodiments of the present invention, rods  1334  may be flexible and have a sufficiently small diameter such that the rods are strong enough to support wire  1332 , but have sufficient flexibility so that rods  1334  bend and/or move relative to wire  1332  during coating. Because wire  1332  does not follow the movement of an individual flexible rod  1334 , the bending/movement of rods  1334  during coating provides additional physical separation between the rods those sections of wire  1332  previously in contact with rods  1334 . Thus, the bending/movement of rods  1334  helps to ensure that all portions of wire  1332  are exposed during deposition so that a desired barrier layer is formed. Alternatively, rods  1334  may be formed by thin wires or strings (e.g. Polyurethane) stretched between bases  1320 . In these embodiments, the individual string/wire bends or change location as a result of the vibration. As noted, wire  1332  does not does not follow the movement of an individual string or wire so that all surfaces of wire  1332  are coated with the barrier material. 
       FIG. 13B  is a perspective view of another coating frame, illustrated as coating frame  1330 B, positionable horizontally in a deposition chamber. Coating frame  1330 B comprises opposing bases  1320 , and a plurality of substantially parallel rods  1324  extending between the bases. Rods  1324  have a generally rectangular shape, and have a plurality of cut-outs or notches  1370  formed therein. Notches  1370  are aligned to create a channel extending about the circumference of frame  1330 C. In these embodiments, wire  1332  is loosely around rods  1324  so that wire  1332  extends through the channel formed by notches  1370 . 
     Similar to the embodiments described above, coating frame  1330 B rotates about a substantially horizontal axis during deposition. As coating frame  1330 B rotates and a rod  1324  moves towards the bottom of the chamber, the sections of loosely wound wire  1332  in contact with channels  1370  will separate from the rod. As these sections of wire  1332  become spaced from channels  1370 , the barrier material will coat the sections of wire  1332  that were previously in contact with the channels, thereby creating a desired barrier layer on the wire. 
       FIG. 13C  is a perspective view of a still other coating frame, illustrated as coating frame  1330 C, configured to be positioned horizontally in a deposition chamber. Notches  1372  are aligned to create a channel extending about the circumference of frame  1330 D. In these embodiments, coating frame  1330 C comprises a tubular member having ridges extending along the length thereof. Ridges  1310  comprise a plurality of notches  1372  therein. In these embodiments, wire  1332  is loosely around frame  1330 C so that wire  1332  extends through the channel formed by notches  1372 . 
     Similar to the embodiments described above, coating frame  1330 C rotates during deposition. As coating frame  1330 C rotates and a ridge  1310  moves towards the bottom of the chamber, the sections of loosely wound wire  1332  in contact with notches  1372  will separate from the channel. As these sections of wire  1332  become spaced from channels  1372 , the barrier material will coat the sections of the wire that were previously in contact with the channels, thereby creating a desired barrier layer on the wire. 
     In an alternative embodiment of  FIG. 13C , coating frame  1330 C may comprise a threaded shaft. In such embodiments, channels  1372  extend around the circumference of the shaft. Therefore, during rotation, sections of wire rotating towards the bottom of the deposition chamber continually separate from the portion of the shaft near the bottom of the chamber. 
       FIG. 13D  is a perspective view of a still other coating frame, illustrated as coating frame  1330 D, configured to be positioned horizontally in a deposition chamber. Coating frame  1330 D comprises opposing bases  1312 , and a plurality of substantially parallel rods  1334  extending between the bases. 
     As shown, bases  1312  also comprise rod guides  1374 . As coating frame  1330 D rotates, the weight of rods  1334  causes the rods to move within guides  1374 , thus alternating the location of rods  1334  with respect to wire  1332 . It would be appreciated that rods  1334  can also rotate during their movement, facilitating minimal drag on wire  1332 . Because rods move relative to wire  1332  during deposition, sections of wire  1332  that are in contact with a rods  1334  become physically separated from the rod. Those sections remain separated from the rod for a period of time that is sufficient to coat the sections with a desired thickness of barrier material. Thus, a substantially continuous barrier layer is formed on wire  1332 . 
     The embodiments of  FIGS. 13A and 13D  have been illustrated with rods  1334  having a generally circular cross-sectional shape. It would be appreciated that rods  1334  may have other cross-sectional shapes in alternative embodiments of the present invention. For example, rods having any of the cross-sectional shapes illustrated in  FIGS. 7A-7D  may be implemented in other embodiments.  FIG. 14  illustrates a still further embodiment of a rod  1434  having an undulating or wavy shape. More specifically, in the embodiments of  FIG. 14 , rod  1434  is flexible and comprises a series of spaced projections  1421 . Adjacent projections  1412  are separated by concave regions  1423  to form an elongate undulating surface. The vertical spacing between the end of a projection  1421  and the center of an adjacent concave region  1423  is substantially small relative to thickness of a wire wound there around so as to impart minimal tension change on the wire during rotation. During deposition of an embodiment implementing rod  1434 , the rod could rotate with respect to the coating frame bases, thereby providing relative movement between the rod and the wire wound around the coating frame. It would be appreciated that rod  1434  is not shown to the scale and the undulations may be smaller than those shown in  FIG. 14 . In certain embodiments, the undulations would not be visible in a to scale illustration. As such, the embodiments of  FIG. 14  are merely illustrative and do not limit the scope of the present invention. 
     As noted above, in certain vapor deposition systems mechanical movement of various elements occurs during operation, thereby resulting in an inherent level of vibration of a coating frame. In the embodiments of  FIGS. 13A-13D , this inherent vibration enhances the relative movement of coating frames  1330  to wire  1332 . In alternative embodiments, the inherent vibration may be amplified using, for example, a spring. In other embodiments, additional vibration may also be added using, for example, the coating frame drive system described above with reference to  FIG. 9A  or through the application of high frequency (e.g. ultra sonic) vibration. 
       FIG. 15A  is a perspective view of an alternative coating frame  1530  that may used in embodiments of the present invention to coat an elongate conductive element with a substantially continuous barrier layer. As shown, coating frame  1530  comprises a plurality of independently rotatable discs  1580 . Each disc  1580  comprises a plurality of support arms  1538  extending from the edge thereof. 
     In the illustrative embodiments of  FIG. 15A , each of the discs  1580  are connected to one or more drive motors which mechanically rotate the discs. It would be appreciated that a variety of methods may be implemented to independently rotate discs  1580 . It would also be appreciated that in certain embodiments discs  1580  may move side to side and/or forward and backwards, relative to a center axis extending through the discs. Such side to side and/or forward or backward movement may assist in minimize tension in the wire. 
     In the embodiments of  FIG. 15A , a wire is loosely wound around discs  1580  so that the wire is supported by supports arms  1538 , in substantially the same manner as described above with reference to  FIGS. 9A and 9B . Coating frame  1530  is positioned in a deposition chamber so that a barrier layer may be applied to the wire. During deposition, one or more discs  1580  rotate, thereby altering the position of the wound wire to coating frame  1530 . This ensures that no portion of the wound wire is in contact with a support arm  1538  for the entirety of the deposition, thereby providing a substantially continuous barrier layer on the wire. 
       FIG. 15A  illustrates embodiments of the present invention in which discs  1538  have an octagonal cross-sectional shape and have support arms  1538  extending from the edges to support a wound wire.  FIG. 15B  illustrates an alternative embodiment in which a disc, referred to as disc  1580 B, has a star shaped. In these embodiments, a wound wire would be supported near the points  1539  of disc  1580 B.  FIG. 15C  illustrates a still other embodiment in which a disc  1580 C as a circular cross-sectional shape, and support arms  1538  extend radially from the edge thereof. It would be appreciated that the shaped discs illustrated in  FIGS. 15A-15C  are merely illustrative and other shapes may also be implemented. 
     As noted above, embodiments of the present invention are generally directed to coating an elongate conductive element with a substantially continuous barrier layer.  FIG. 16  is a schematic block diagram illustrating embodiments of a vapor deposition apparatus, referred to as continuous vapor deposition apparatus  1650 , configured to apply a substantially continuous barrier layer to an elongate conductive element. As shown in  FIG. 16 , continuous vapor deposition apparatus  1650  comprises a vapor supply system  1606  configured to supply vapor material to an internal deposition chamber  1604 . Vapor supply system  1606  includes a vaporization chamber  1600  that vaporizes a quantity of a dimer inserted therein, and a pyrolysis chamber  1602  connected to vaporization chamber  1600 . Once transferred to pyrolysis chamber  1602 , the vaporized dimer is pyrolized at temperatures of approximately 400 to 750 degrees Celsius to form a desired monomer vapor. Following pyrolysis, the monomer vapor is transferred to internal deposition chamber  1604 , where, as described below, the vapor is used forms a substantially continuous barrier layer on the surface of a conductive element positioned in the chamber. In specific embodiments of the present invention, vapor deposition apparatus vaporizes a parylene dimer, and forms a parylene coating on a conductive element within internal deposition chamber  1604 . 
     Following deposition and condensation, residual vapor is removed from deposition chamber  1604  and transferred to cold trap  1618 . Cold trap  1618  serves to rapidly condense and polymerize any residual vapors. Vacuum pump  1608  is connected to cold trap  1618  and maintains continual negative pressure within internal deposition chamber  1604  and cold trap  1618 . 
     As shown in  FIG. 16 , continuous vapor deposition apparatus  1650  further comprises a guide system  1660  positioned adjacent to internal deposition chamber  1604 . As described in greater detail below, guide system  1660  is configured to apply a tensile force to a conductive element extending through internal deposition chamber  1604 , and to control the movement of the conductive element through the internal deposition chamber during deposition. In the embodiment of  FIG. 16 , guide system  1660  comprises a conductive element supply system  1624  and a conductive element collection system  1626 . As described in greater detail below, supply system  1624  is configured to guide a conductive element from a spool to the interior of internal deposition chamber  1604 . Also as described below, collection system  1626  is configured to remove the conductive element from the internal deposition chamber  1604 , and to spool the insulated conductive element exiting the internal deposition chamber. 
     As noted above, guide system  1660  is positioned adjacent to internal deposition chamber  1604 . In the embodiments of  FIG. 16 , guide system  1660  is positioned within a sealed chamber, referred to herein as external deposition chamber  1620 . External deposition  1620  provides a substantially contaminate free environment to house guide system  1660 . 
     Furthermore, as shown in  FIG. 16 , external deposition chamber  1620  is connected to a vacuum pump  1622  that maintains negative pressure within the external chamber during operation. In certain embodiments, vacuum pumps  1608  and  1622  maintain the same pressure within internal and external deposition chambers  1604 ,  1620 . In alternative embodiments, vacuum pumps  1608  and  1622  maintain different pressures with in internal and external deposition chambers  1604 ,  1620 . 
     It would also be appreciated that in certain embodiments, vacuum may be removed from external deposition chamber  1620 , while maintaining deposition vacuum pressure in internal deposition chamber  1604 . In such embodiments, uncoated or coated spools of wire may be loaded into, or removed from, external deposition chamber  1604  without disturbing the deposition conditions (i.e. pressure and temperature) in internal deposition chamber. 
       FIG. 17  is an additional schematic diagram of continuous vapor deposition apparatus  1650 . As noted above, continuous vapor deposition apparatus  1650  includes a guide system  1660  to control movement of a wire  1732  through internal deposition chamber  1604 . Also as noted, guide system  1660  a conductive element supply system  1624 , and a conductive element collection system  1626 . Supply system  1624  guides wire  1732  from spool  1740  to internal deposition chamber  1604 . As described in detail with reference to  FIG. 18A , wire  1732  extends through a measurement apparatus  1742  that measures the diameter of wire  1732 , and around one or more wire guides  1760  before entering internal deposition chamber  1604 . 
     Collection system  1626  guides wire  1732  from internal deposition chamber  1604  to a spool  1752 . Specifically, upon exiting internal deposition chamber  1604 , wire  1732  extends around one or more wire guides  1746 , and through a second measurement apparatus  1748 . Measurement apparatus  1748  is used to measure the thickness of the barrier layer on wire  1732 . Coated wire  1732  is wound about spool  1752 . 
     As noted above, in embodiments of the present invention, internal deposition chamber  1604  is positioned in an external deposition chamber  1620 . In embodiments of the present invention, external deposition chamber  1620  comprises a lid  1707  that provides access to internal deposition chamber  1604 . Similarly, internal deposition chamber  1604  comprises a lid  1709  which provides access of cleaning the chamber. 
       FIG. 18A  is a schematic diagram of one embodiment of conductive element supply system  1624 . As noted, supply system  1624  comprises a spool  1740  of uncoated wire  1732 . 
     Wire  1732  extends from spool  1740  over a first wire guide  1760 A through laser measurement system  1742 . Laser measurement system  1742  determines the pre-coating thickness of wire  1732 . As described below, this measured thickness is used during measurement of coating thickness by collection system  1626 . Wire  1732  extends over and under, respectively, second and third wire guides  1760 B and  1760 C into internal deposition chamber  1604 . It would be appreciated that a varying number of wire guides, locations and materials may be implemented in alternative embodiments of the present invention depending on, for example, the conductive element being coated. 
     Wire  1732  enters internal deposition chamber  1604  through an opening  1771  in a plug  1768 . Opening  1771  in plug  1768  is of sufficient size to accommodate the passage of wire  1732  with little to no interference with the wire. For example, in one specific embodiment, opening  1771  has a 5 mm entrance diameter that tapers to 35 microns for a length of 10 mm, and expands to a diameter of 2 mm at the exit into internal deposition chamber  1604 . 
     As described in greater detail below, the section of wire  1732  may follow a variety of travel paths through internal deposition chamber  1604 . Wire  1732  exits through an opening  1773  in a plug  1769 , shown in  FIG. 18B . Plug  1769  and opening  1773  are substantially the same as plug  1769  and opening  1771 , respectively, of  FIG. 18A . 
       FIG. 18B  is a schematic diagram of conductive element collection system  1626 . As shown, upon exiting opening  1773 , coated wire  1732  extends under a first wire guide  1746 A and over a second guide wire  1746 B to laser measurement system  1748 . Coated wire is then wound onto spool  1752 . It would be appreciated that a varying number of wire guides, locations and materials may be implemented in alternative embodiments of the present invention depending on, for example, the conductive element being coated. 
     Laser measurement system  1748  is configured to measure the thickness of the barrier layer on wire  1732 . In certain embodiments, laser measurement system  1748  measures the thickness using the data obtained by laser measurement system  1742  in supply system  1624 . 
     In certain embodiments, laser measurement system  1742  may determine that the barrier layer does not have a sufficient thickness at one or more locations. In these circumstances, guide system  1660  is configured to reverse the direction of travel of wire  1732 , and position those insufficiently coated sections of wire within internal deposition chamber  1604  for further deposition. 
     As noted,  FIGS. 18A and 18B  illustrate the details of supply system  1624  and collection system  1626 . It would be appreciated that one or both of supply system  1624  and collection system  1626  function to control the tension on wire  1732 . For example, in certain embodiments, collection system  1626  pulls wire  1732  through internal deposition chamber  1604 , and supply system  1624  operates to release wire as necessary so that the desired tension is maintained. 
     Also as noted, in certain circumstances guide system  1660  is configured to reverse the direction of travel of wire  1732 . In specific such embodiments, supply system  1624  pulls wire  1732  through internal deposition chamber  1604 , and collection system  1626  operates to release wire as necessary so that the desired tension is maintained. 
       FIGS. 18A and 18B  illustrate the use of plugs  1768  and  1769  through which wire  1732  passes to enter and exit, respectively, internal deposition chamber  1604 . In embodiments of the present invention, plugs  1768 ,  1769  are removable to facilitate cleaning of internal deposition chamber  1604 . In certain embodiments, plugs  1768 ,  1769  are formed from, for example, polytetrafluoroethylene (PTFE). 
     As noted above, wire  1732  may follow a variety of travel paths through internal deposition chamber  1604 .  FIGS. 19A-19D  illustrate several different paths followed by wire  1732  in embodiments of the present invention. In certain such embodiments, wire  1732  is manually threaded from conductive element supply system  1624  through internal deposition chamber  1604  to conductive element supply system  1626 . In other embodiments, guide system  1660  comprises a wire feed module which threads wire  1732  from spool  1740  to spool  1752 . 
       FIG. 19A  illustrates the simplest configuration in which wire  1732  enters through plug  1768 , travels linearly through internal deposition chamber  1604 , and exits through plug  1769 . This illustrative configuration has the advantage of a simple travel path, and the need for few or no elements to support wire  1732  within the chamber. It would be appreciated that, in certain embodiments, the thickness of a deposited barrier layer may correspond to the length of time spent within internal deposition chamber  1604 . The linear arrangement of  FIG. 19A  may alter the barrier layer thickness by conducting multiple passes through chamber  1604  with wire  1732 . In alternative embodiments, internal deposition chamber  1604  may be designed to have a long length (eg. meters in length) through which wire  1732  extends. 
       FIG. 19B  illustrates an alternative configuration in which several rods  1934  are provided within internal deposition chamber  1604 . In these embodiments, rods  1934  are positioned in two horizontal, substantially parallel rows  1936 . Wire  1732  enters internal deposition chamber  1604  through plug  1768  and is wound through the pattern of rods  1934 . Wire  1732  exits through plug  1769 .  FIG. 19C  illustrates embodiment similar to those of  FIG. 19B  in which rods  1934  are disposed in two vertical, substantially parallel rows  1938 . 
       FIG. 19C  illustrates another embodiment in which a coating frame  1930  that is substantially the same as the coating frame described above with reference to  FIGS. 3A and 3B , is positioned in internal deposition chamber  1604 . In these embodiments, wire  1732  is wound around rods  1934  in a helical pattern. 
     In certain embodiments, wire  1732  may directly contact rods  1934  within internal deposition chamber  1604 . In alternative embodiments, rods  1934  have one or more guide members  1956  that are configured to guide the wire through internal deposition chamber  1604 .  FIG. 19E  illustrates one exemplary arrangement of a guide member  1956  comprising a plurality of notches  1958 . In these embodiments, notches  1958  receive wire  1732  therein, and substantially prevent movement of the wire in directions other than the direction of travel. 
     As noted above, guide system  1660  is configured to move sections of wire  1732  through internal deposition chamber  1604 . In certain embodiments of the present invention, wire  1732  remains stationary during deposition. In such embodiments, a coated section of wire may be removed from internal deposition chamber  1604 , and an uncoated section may be simultaneously positioned in the chamber. Such movement may occur between sequential deposition processes. 
     In other embodiments, guide system  1660  is configured to continually move sections of wire  1732  through internal deposition chamber  1604  during a deposition process, sometimes referred to herein as deposition. In such embodiments, the barrier layer is provided on wire  1732  as it moves through internal deposition chamber  1604 . Guide system  1660  is configured to move a section of wire  1732  at a speed that does not damage the wire, and which ensures that the section of conductive element is coated with a desired thickness of barrier material. 
     It would be appreciated that variations in the thickness of the barrier layer may be achieved by altering the time a section of wire  1732  remains within internal deposition chamber  1604 . For example, in certain embodiments, the speed at which guide system  1660  moves a section of wire  1732  through internal deposition chamber  1604  may increased or decreased to alter the barrier layer thickness. Alternatively, as noted above, guide system  1660  is configured to reverse the direction of travel of wire  1732  so that a section may be moved forward as well as backwards to obtain a barrier layer of desired thickness. 
       FIG. 20  is a schematic diagram illustrating an alternative continuous vapor deposition apparatus  2050  in accordance with embodiments of the present invention. Similar to the embodiments described above, continuous vapor deposition apparatus  2050  comprises an internal deposition chamber  1604 , an external deposition chamber  1620 , a conductive element supply system  1624  and a conductive element collection system  1626 . Positioned in internal deposition chamber  1604  is a coating frame  2032  having wire  2032  wound there around. 
     Continuous vapor deposition apparatus  2050  further comprises a plurality of independently operable vapor supply systems  2006 . Each vapor supply system  2006  is separately connected to internal deposition chamber  1604  so as to provide a vapor material to the chamber. A shut off valve  2090  is provided between each vapor supply system and internal deposition  1604  to control the flow of vapor into the chamber. 
     It would be appreciated that the operational time period for conventional vapor deposition apparatus is limited by the amount of material that is vaporized. This is a limitation because only a discrete amount of dimer may be loaded into the vaporization chamber at anytime. The embodiments of  FIG. 20  increase the operational period for coating a conductive element because each vapor supply system  2006  may be independently operated. Therefore, one system may be loaded with dimer while the other is providing vapor. Thus, a continual supply of vapor may be provide to internal deposition chamber  1604 , with only the non-operational time required to active an additional supply system. 
     The multiple vapor supply systems  2006  of  FIG. 20  may be particularly beneficial in embodiments in which a section of wire is continually moved through internal deposition chamber  1604 . By providing, through the use of multiple vapor supply systems  2006 , a continuous flow of the vapor, the need to stop movement of wire  1732  through the chamber to add additional dimer is substantially eliminated. Thus, a wires ranging anywhere from several to hundreds of meters in length may be coated with a substantially continuous barrier layer. 
       FIG. 21  is a high level flowchart illustrating a method  2100  for coating an elongate, uncoated conductive element with a substantially continuous barrier layer using a continuous vapor deposition apparatus of the present invention. In such embodiments, the continuous vapor deposition apparatus comprises an internal deposition chamber. 
     The method begins at block  2102  in which a first section of the elongate conductive element is positioned in the internal deposition chamber. The first section of the elongate conductive element extends through the chamber between opposing sections of a guide system positioned external to the chamber. The method continues to block  2104  where a barrier material is deposited on the section of the elongate conductive element that is in the internal deposition chamber. 
     At block  2106 , the coated first section is removed from the deposition chamber by the guide system. Simultaneously, the guide system positions a second section of elongate conductive element in the internal deposition chamber for deposition. 
     As noted above, in certain, a coated section of a conductive may be removed from an internal deposition chamber, and an uncoated section may be simultaneously positioned in the chamber between sequential deposition processes. In other embodiments, a conductive element may be continually moved through the internal deposition during deposition. 
     As noted elsewhere herein, embodiments of the present invention are directed to coating an uncoated elongate conductive element with a substantially continuous barrier layer to form an insulated conductive element. Certain embodiments of the present invention described in detail below are directed to forming the substantially continuous barrier layer through relative movement of a wire to a coating frame between sequential coatings of a barrier material.  FIGS. 22A and 22B  illustrate two exemplary such embodiments. 
       FIG. 22A  is flowchart illustrating a method  2200 A for coating an elongate, uncoated conductive element with a substantially continuous barrier layer, through motion of a wire relative to a coating frame between sequential coatings Method  2200 A begins at block  2202  in which uncoated conductive element is wound around a plurality of spaced rods. The method continues at block  2204  in which a barrier material is deposited on the conductive element to form an intermediate layer having uncoated gaps therein.  FIG. 23A  illustrates an exemplary conductive element, shown as wire  2332 , having an intermediate layer  2344  thereon. Intermediate layer  2344  has gaps  2338  therein. It would be appreciated that the thickness of layer  2344  relative to the size of gap  2338  shown in  FIG. 23A  is not shown to scale, and is merely illustrative. 
     At block  2206 , following deposition of the intermediate layer on the conductive element, the coated conductive element is moved relative to the coating frame such that the uncoated gaps are physically spaces from the rods. In other words, the conductive element is moved relative to the frame so that the gaps are exposed and may receive a coating of barrier material. At block  2208 , a barrier material is deposited on the coated conductive element. This coating of barrier material is referred to herein as a secondary layer. As noted, because the gaps in the intermediate layer are exposed, and are not in direct contact with the supports, the gaps receive a coating of the secondary layer to form a substantially continuous barrier layer. At block  2210 , the insulated conductive element is unwound from the coating frame. 
       FIG. 23B  illustrates an insulated conductive element comprising a barrier layer  2336  formed from an intermediate layer  2344  and a secondary layer  2342 . For ease of illustration, secondary layer  2342  and intermediate layer  2344  have been shown using different cross-hatching. It would be appreciated that layers  2342  and  2344  may comprise the same or different barrier material. In certain embodiments, both intermediate layer  2344  and secondary later  2342  each comprise layers of parylene. 
       FIG. 22A  illustrates embodiments of the present invention in which the conductive element receives two coatings of a barrier material. It would be appreciated that each of the coatings may have the same or different thickness. It would also be appreciated that in certain embodiments additional coatings may be applied. 
       FIG. 22B  illustrates an alternative embodiments of the present invention in which a substantially continuous barrier layer is formed by transferring a conductive element from a first coating frame to a second coating frame between sequential coatings of a barrier material. Method  2200 B of  FIG. 22B  begins at block  2220  in which an uncoated conductive element is wound around a coating frame comprising a plurality of spaced rods. The method continues at block  2222  where a barrier material is deposited on the conductive element to form an intermediate layer having uncoated gaps therein. As noted above,  FIG. 23A  illustrates an exemplary conductive element, shown as wire  2332 , having an intermediate layer  2344  thereon. Intermediate layer  2344  has gaps  2338  therein. 
     At block  2224 , the conductive element having the intermediate layer thereon is transferred from the first coating frame to a second coating frame comprising a plurality of spaced rods. The coated conductive element is wound around the second coating frame such that the uncoated gaps in the intermediate layer are physically spaced from the rods. In other words, the conductive element is wound around the second frame so that the gaps are exposed and may receive a coating of barrier material. 
     At block  2226 , a barrier material is deposited on the coated conductive element. This coating of barrier material is referred to herein as a secondary layer. Because, as noted, the coated conductive element is wound around the second coating frame such that the gaps in the intermediate layer are exposed, the gaps receive a coating of the secondary layer to form a substantially continuous barrier layer. At block  2228 , the insulated conductive element is unwound from the second coating frame. 
     As noted above,  FIG. 23B  illustrates an insulated conductive element comprising a barrier layer  2336  formed from an intermediate layer  2344  and a secondary layer  2342 . For ease of illustration, secondary layer  2342  and intermediate layer  2344  have been shown using different cross-hatching. It would be appreciated that layers  2342  and  2344  may comprise the same or different barrier material. In certain embodiments, both intermediate layer  2344  and secondary later  2342  comprise layers of parylene. 
     As noted above,  FIG. 22B  illustrates embodiments of the present invention in which a coated conductive element is transferred from a first coating frame to a second coating frame between coats of a barrier material.  FIG. 24A  is a schematic diagram illustrating one exemplary mechanism for transferring a coated wire  2432  from a first coating frame  2472  to a second coating frame  2476 . In these embodiments, the transfer mechanism comprises a linear slide  2476  and a wire guide  2478 . As wire  2432  is wound from coating frame  2472 , the wire passes through wire guide  2478  to coating frame  2476 . Wire guide  2478  moves along slide  2474  to control the location of wire  2432  as it is wound around coating frame  2476 . 
       FIG. 24B  illustrates embodiments of the present invention for transferring a coated wire  2432  from a coating frame  2472  to a wire spool  2486 . In these embodiments, the transfer mechanism comprises first and second wire guides  2482  and  2484 . As wire  2432  is wound from coating frame  2472 , the wire passes through wire guide  2482  to wire  2484  which aligns the wire with spool  2486 . 
     As noted above, embodiments of the present invention are generally directed to using vapor deposition to coat elongate conductive elements with a protective barrier layer. The barrier layer may be applied to the conductive elements for a variety of reasons including, but not limited to providing electrical insulation between adjacent conductive elements, providing biocompatibility, immobilization of microscopic particles, and ensuring that the conductive elements are passive, as well as providing physical isolation of the conductive elements from moisture, chemicals, and other substances. 
     In certain embodiments, the barrier layer utilized in embodiments of the present invention is a polymeric material. In one particular embodiment, the barrier layer is parylene. Parylene is the generic name for a variety of vapor deposited poly-para-xylylenes. These materials form highly-crystalline polymers that may be applied as conformal coatings and films. Parylene, unlike other polymeric materials, is not manufactured or sold as a polymer. Rather it is produced by vapor-phase deposition and polymerization of para-xylylene or its derivatives. 
     There are a variety of derivatives and isomers of parylene. The most common variants include Parylene C, Parylene N, and Parylene D. It would be appreciated that other variants of parylene are also commercially available. It would be appreciated that substantially any variant of parylene may be used in embodiments of the present invention. 
     It would also be appreciated that alternative barrier materials may be utilized in embodiments of the present invention. Exemplary alternative barrier materials include, but are not limited to, Polysilicon, Silicon dioxide and Silicone nitride. 
     As noted elsewhere herein, coating frames, rods, support arms etc., described above may be formed from any biocompatible material which has sufficient strength to maintain a desired shaped. In specific embodiments, a coating frame, rod, support arm, etc. may be formed from stainless steel. In certain embodiments, a coating frame, rod, support arm, etc. may be coated with, for example, PTFE to reduce the bonding between the barrier material and a coating frame, rod, support arm, etc. 
     Embodiments of the present invention have been described herein with reference to an elongate conductive element having a substantially continuous barrier layer, or substantially continuous sections. It would be appreciated that the thickness of a substantially continuously coated section or layer need not be consistent across the entire section or layer. 
     As noted above, insulated conductive elements in accordance with embodiments of the present invention may be implemented in an implantable stimulating assembly. Such a stimulating assembly may be used for a variety of cochlear implants, such as short stimulating assemblies, straight stimulating assemblies, peri-modiolar stimulating assemblies, etc. Insulated conductive elements in accordance embodiments of the present invention may also be implemented in any implantable medical device utilizing coated conductive elements. For example, embodiments of the present invention may be implemented in any neurostimulator now know or later developed, such as brain stimulators, cardiac pacemakers/defibrillators, functional electrical stimulators (FES), spinal cord stimulators (SCS), bladder stimulators, etc. 
     Further features and advantages of the present invention are described in commonly owned and co-pending U.S. Utility patent applications entitled “An Insulated Conductive Element Comprising Substantially Continuously Coated Sections Separated By Uncoated Gaps,” filed Sep. 9, 2009; “An Insulated Conductive Element Having A Substantially Continuous Barrier Layer Formed Via Relative Motion During Deposition,” filed Sep. 9, 2009; and “An Insulated Conductive Element Comprising Substantially Continuous Barrier Layer Formed Through Multiple Coatings,” filed Sep. 9, 2009. The content of these applications are hereby incorporated by reference herein. 
     The invention described and claimed herein is not to be limited in scope by the specific preferred embodiments herein disclosed, since these embodiments are intended as illustrations, and not limitations, of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.