Patent Description:
Medical implant devices are becoming more frequently used. Some medical implant devices include a lead that delivers stimulation. For example, deep brain stimulation involves implanting a lead assembly within a particular part of the brain. The lead assembly can include a coated wire to which one or more electrodes are attached. A lead assembly can include a conductive material and can take the form of an insulated wire. A connector can connect an end of the lead assembly to a flexible extension, which can connect (via another connector) to a neurostimulator. The neurostimulator can include circuitry that determines characteristics of stimulation to be delivered by the electrode(s).

Frequently, the neurostimulator is implanted near the collarbone. The neurostimulator can receive wireless signals from a non-implanted controller device. For example, a wireless signal can correspond to an instruction to transition to a power-on or power-off state and/or to an instruction to use a particular stimulation setting.

Thus, frequently, deep-brain-stimulation devices include multiple connectors and a sizable extension. Each connector can electrically couple the connecting components and can include (for example) a screw, a spring-lock mechanism, a welded interface or a bonded interface. However, each connection has the potential to disconnect or fracture, which can cause the device to fail. Further, the extension can cause undesired biological responses, such as subcutaneous bleeding. Thus, it would be desirable to develop a neuromodulation device that maintained connections between stimulating electrodes and circuitry but that decreased the risk of adverse events and device failure. <CIT> describes devices, systems, and techniques for dissipating electromagnetic interference (EMI) induced energy in a medical device. <CIT> describes an implantable medical lead and medical device systems employing such leads for medical applications, such as, e.g., neural stimulation, deep brain stimulation, and/or sensing of bioelectrical signals. <CIT> describes a cylindrical microelectrode array having an elongated cylindrical core, and a multilayer structure conformally folded around and affixed to the cylindrical core so as to extend between opposite ends of the core. <CIT> describes an apparatus, a system and methods for modulating and monitoring tissue having an elongate member with proximal and distal ends and a plurality of annular stimulating electrodes axially arranged along the elongate member. The stimulating electrodes are disposed near the distal end and are adapted to pass current into tissue. At least one of the annular stimulating electrodes has at least three independent stimulation points on the electrode. The apparatus also includes a plurality of recording electrodes that are adapted to measure local tissue potentials and a plurality of conductors are coupled with the recording and stimulating electrodes. An optional multiple contact connecting terminal may be coupled with the conductors and is disposed near the proximal end of the elongate member.

According to the present invention, a method of manufacturing a lead assembly according to claim <NUM> is provided.

Further, a stimulation system according to claim <NUM> is provided.

In some instances, a deep brain stimulation system is provided that includes a set of electrodes, a set of traces and a neurostimulator. In some instances, the deep brain stimulation system includes a monolithic thin-film lead assembly (e.g., a cable) that is fabricated using a same layer of base material (e.g., an insulating material or dielectric material, such as a polymer material). The base material and/or the monolithic thin-film lead assembly itself can have a thickness that is (for example) less than about <NUM>. The monolithic thin-film lead assembly can include a set of electrodes disposed on a first portion of the base material and a set of conductive traces that extend across a second portion of the base material. Each trace may connect to one of the set of electrodes. The monolithic nature of the thin-film lead assembly can promote stable physical and electrical connections between components of the deep brain stimulation system.

The monolithic thin-film lead assembly can include one or more helically shaped components. For example, a helical portion can extend across part or all of the monolithic thin-film lead assembly at a pitch from <NUM> to <NUM>. The pitch may, but need not, be consistent across a length of the thin-film lead assembly. The helical portion can include, is composed of and/or can support the set of electrodes and/or the set of traces. In some instances, the set of electrodes and/or the set of traces are disposed to collectively be in a helical shape. The base material and can be a supporting structure that is shaped in a hollow or solid cylindrical shape. The supporting structure may be formed with a dielectric material such as a polymer having suitable dielectric, flexibility and biocompatibility characteristics. Polyurethane, polycarbonate, silicone, polyethylene, fluoropolymer and/or other medical polymers, copolymers and combinations or blends may be used. The conductive material for the traces may be any suitable conductor such as stainless steel, silver, copper or other conductive materials, which may have separate coatings or sheathing for anticorrosive, insulative and/or protective reasons.

The helical shape can wrap around a cylindrically shaped base material. Each trace can extend between and/or electrically connect an electrode and the neurostimulator. In some instances, an end of the trace is electrically and/or physically connected to a bonding pad that is part of or is connected to the neurostimulator.

In some instances, the neurostimulator is configured to be implanted under the scalp, rather than near the collar bone. For example, the neurostimulator can be positioned between the skull and scalp in a sub-scalp or subgaleal space. This positioning can reduce an overall size of the deep brain stimulation system, as the device need not extend beyond the scalp. Further, the extension can then be shortened, which can reduce the likelihood that subcutaneous bleeding will occur. It can further yet reduce the number of incisions that are made during an implantation procedure, such that infection risk and the risk of other incision-related complications is also reduced.

<FIG> show multiple views of a deep brain stimulation system that includes a neurostimulator implanted near the collar bone. The deep brain stimulation system can include a lead assembly <NUM> that includes electrodes and is implanted into the brain, such that the portion of lead assembly <NUM> that includes the electrodes are positioned at a target site. Lead assembly <NUM> can further include a flexible extension <NUM> that extends from the electrode portion. At least part of extension <NUM> can run beneath the skin and connect to a neurostimulator <NUM> that is implanted near the collar bone.

<FIG> show multiple views of a deep brain stimulation system that includes a neurostimulator implanted under the scalp. The deep brain stimulation system can include a lead assembly <NUM> that includes electrodes and is implanted into the brain, such that the portion of lead assembly <NUM> that includes the electrodes are positioned at a target site. Lead assembly <NUM> can include an extension <NUM> portion. At least part of extension <NUM> can run beneath the skin and connect to a neurostimulator <NUM>. Lead assembly <NUM> can be configured such the electrode portion and extension <NUM> portion are monolithic.

In this instance, neurostimulator <NUM> is implanted under the scalp. For example, neurostimulator <NUM> can be attached to a superficial surface of the skull using an adhesive, orthopedic fixation device, screw, and so on. In some instances, an entire surface of neurostimulator <NUM> (e.g., an entire bottom surface) can be attached to the skull (e.g., by applying an adhesive to the entire surface). In some instances, an attachment is made at one or more contact points of neurostimulator <NUM>. For example, neurostimulator <NUM> can be configured to include one or more holes through which one or more screws or pins can be inserted.

In some instances, multiple lead assemblies <NUM> are implanted (e.g., in each cerebral hemisphere). Each of multiple lead assemblies <NUM> can be connected to a single neurostimulator <NUM>.

Neurostimulator <NUM> can include (for example) a housing, a power source, an antenna and an electronics module (e.g., a computing system). The housing may be comprised of materials that are biocompatible such as bioceramics or bioglasses for radio frequency transparency, or metals such as titanium. The power source may be within the housing and connected (e.g., electrically connected) to the electronics module to power and operate the components of the electronics module. The antenna may be connected (e.g., electrically connected) to the electronics module for wireless communication with external devices via, for example, radiofrequency (RF) telemetry.

Neurostimulator <NUM> can include one or more bonding pads that are electrically connected to the electronics module. Lead assembly <NUM> can be attached to the one or more bonding pads (e.g., via a welding process) to electrically connect the electronics module to electrodes in lead assembly <NUM>. The electronics module can then apply a signal or electrical current to conductive traces of lead assembly <NUM> connected. The electronics module may include discrete and/or integrated electronic circuit components that implement analog and/or digital circuits capable of producing the functions attributed to the neuromodulation devices or systems such as applying or delivering neural stimulation to a patient. In various examples, the electronics module may include software and/or electronic circuit components such as a pulse generator that generates a signal to deliver a voltage, current, optical, or ultrasonic stimulation to a neural structure via electrodes, a controller that determines or senses electrical activity and physiological responses via the electrodes and sensors, controls stimulation parameters of the pulse generator (e.g., control stimulation parameters based on feedback from the physiological responses), and/or causes delivery of the stimulation via the pulse generator and electrodes, and a memory with program instructions operable on by the pulse generator and the controller to perform one or more processes for applying or delivering neural stimulation.

In various examples, the lead assembly <NUM> is a monolithic structure that includes a cable or lead body. In some examples, the lead assembly <NUM> further includes one or more electrode assemblies having one or more electrodes, and optionally one or more sensors. In some examples, the lead assembly <NUM> further includes a conductive connector (e.g., comprising copper, silver or gold). In certain examples, the connector is bonding material that bonds conductor material of the cable to the electronics module of the implantable neurostimulator <NUM> (e.g., at a bonding pad). A bonding material may be a conductive epoxy or a metallic solder or weld such as platinum. In other examples, the connector is conductive wire or conductive traces (in addition to or instead of bonding pads). In alternative examples, the neurostimulator <NUM> and the cable are designed to connect with one another via a mechanical connector, such as a pin and sleeve connector, snap and lock connector, flexible printed circuit connectors, or other means known to those of ordinary skill in the art.

<FIG> shows a spiraled lead assembly. <FIG> shows an extended lead assembly. The lead assembly can be monolithic, such that a single substrate (e.g., configured to different shapes) extends across the entire lead assembly. The lead assembly can include a cable having a proximal end <NUM> and a distal end <NUM>. As used herein, the term "proximal end" refers to a first end of the main body, while the term "distal end" refers to a second end opposing the first end. For example, the proximal end may be an end of the main body, which is closest to the user, and the distal end may be an end of the main body, which is furthest from the user.

The cable may comprise a supporting structure and one or more conductive traces formed on a portion of supporting structure. As used herein, the term "formed on" refers to a structure or feature that is formed on a surface of another structure or feature, a structure or feature that is formed within another structure or feature, or a structure or feature that is formed both on and within another structure or feature. Further, the cable includes a set of electrodes <NUM> at (e.g., formed on, disposed at, attached to) distal end <NUM>. Each electrode <NUM> and trace can include a conductive material.

At proximal end <NUM>, each conductive trace can terminate at a conductive bonding pad <NUM>. In some instances, the distal portion of the lead assembly (that includes electrodes <NUM>) is rigid, while an intermediate portion that extends from the distal portion to the bonding pads (and includes the traces) is flexible. Bonding pads <NUM> can include a bonding material, which can be (for example) a conductive epoxy or a metallic solder or weld such as platinum. It will be appreciated that alternative connectors (e.g., to be used instead of in addition to bonding pads <NUM>) are contemplated. For example, a mechanical connector (e.g., a pin and sleeve connector, snap and lock connector, flexible printed circuit connector) may be used.

In some examples, the supporting structure extends from proximal end <NUM> to the distal end <NUM>. In some examples, the supporting structure may be made of one or more layers of dielectric material (i.e., an insulator). The dielectric material may be selected from the group of electrically nonconductive materials consisting of organic or inorganic polymers, ceramics, glass, glass-ceramics, polyimide-epoxy, epoxy-fiberglass, and the like. In certain examples, the dielectric material is a polymer of imide monomers (i.e., a polyimide), a liquid crystal polymer (LCP) such as Kevlar®, parylene, polyether ether ketone (PEEK), or combinations thereof. In other examples, the supporting structure may be made of one or more layers of dielectric material formed on a substrate. The substrate may be made from any type of metallic or non-metallic material.

The supporting structure can comprise one or more layers of dielectric material, and optionally the substrate, has a thickness (t) from proximal end <NUM> to distal end <NUM>. In some examples, the thickness (t) is from <NUM> to <NUM>, for example about <NUM> or about <NUM>. As used herein, the terms "substantially," "approximately" and "about" are defined as being largely but not necessarily wholly what is specified (and include wholly what is specified) as understood by one of ordinary skill in the art. In any disclosed examples, the term "substantially," "approximately," or "about" may be substituted with "within [a percentage] of" what is specified, where the percentage includes <NUM>, <NUM>, <NUM>, and <NUM> percent. In some examples, the supporting structure <NUM> has a length (I) of <NUM> to <NUM> or <NUM> to <NUM>, e.g., about <NUM> (see, e.g., <FIG>). In some examples, the supporting structure has a width (w) from a first side to a second side. In some embodiments, the width (w) is from <NUM> to <NUM>, for example about <NUM> or about <NUM>.

In some examples, the one or more conductive traces are a plurality of traces, for example, two or more conductive traces or from two to twenty-four conductive traces. The plurality of conductive trace are comprised of one or more layers of conductive material. The conductive material may include pure metals, metal alloys, combinations of metals and dielectrics, and the like. For example, the conductive material may be copper (Cu), gold (Au), silver (Ag), gold/chromium (Au/Cr), etc. In some examples, the conductive material also has thermal expansion characteristics or a coefficient of thermal expansion (CTE) that is approximately equal to that of CTE of the supporting structure. Matching the CTE of components that contact one another can be desirable because it eliminates the development of thermal stresses, which may occur during fabrication and the operation of the cable, and thus eliminates a known cause of mechanical failure in the components.

The one or more conductive traces may be deposited onto a surface of the supporting structure by using thin film deposition techniques well known to those skilled in the art such as by sputter deposition, chemical vapor deposition, metal organic chemical vapor deposition, electroplating, electroless plating, and the like. In some examples, the thickness of the one or more conductive traces is dependent on the particular impedance desired for conductor, in order to ensure excellent signal integrity (e.g., electrical signal integrity for stimulation or recording). For example, if a conductor having a relatively high impedance is desired, a small thickness of conductive material should be deposited onto the supporting structure. If, however, a signal plane having a relatively low impedance is desired, a greater thickness of electrically conductive material should be deposited onto the supporting structure. In certain examples, each of the one or more conductive traces has a thickness (d). In some examples, the thickness (d) is from <NUM> to <NUM> or from <NUM> to <NUM>, for example about <NUM> or about <NUM>. In some embodiments, each of the one or more conductive traces has a length (m) of about <NUM> to <NUM> or <NUM> to <NUM>, e.g., about <NUM>. In certain examples, each of the one or more conductive traces extends from proximal end <NUM> to distal end <NUM>. In some examples, each of the one or more conductive traces has a width (y) from <NUM> to <NUM>, for example about <NUM> or about <NUM>.

As shown in <FIG>, the lead assembly may be formed with a predetermined shape in accordance with aspects of the present disclosure. In particular, the lead assembly may be formed with a predetermined shape from a prefabricated wafer or panel of dielectric material or optionally a substrate. For example, the lead assembly may be laser cut from a prefabricated wafer or panel in a spiral shape. The spiral shape may include characteristics designed to maximize the length of the lead assembly that can be fabricated from a single wafer or panel. Conventionally, wafers or panels have a diameter, length, and/or width of less than <NUM>. In some examples, the characteristics of the spiral shape include a predetermined number of turns and a predetermined pitch (p) between each of the turns to maximize the overall length obtainable for the lead assembly. In certain examples, the spiral shape has <NUM> or more turns, for example from <NUM> to <NUM> turns, and a pitch (p) between each of the turns from <NUM> to <NUM> or from <NUM> to <NUM>, for example about <NUM>. Accordingly, the spiral shape can maximize the length of the lead assembly hat can be fabricated from a single wafer or panel. For example, a single wafer or panel with a limited diameter, length, and/or width of less than <NUM>, can be used to fabricate a lead assembly with a length of <NUM> to <NUM>, <NUM> to <NUM>, or <NUM> to <NUM>, e.g., about <NUM>, using the spiral shape.

The lead assembly may further comprise an electrode assembly at distal end <NUM>. The electrode assembly can include the supporting structure and a set of microelectronic structures disposed on the supporting structure. The microelectronic structures can include electrodes <NUM>, a wiring layer, and optional contact(s). In various examples, the supporting structure of the lead assembly and the supporting structure of the electrode assembly are the same structure (i.e., the supporting structure is continuous from the proximal end <NUM> to the distal end <NUM>), which thus creates a monolithic cable. In some examples, the supporting structure for the electrode assembly comprising the one or more layers of dielectric material, and optionally the substrate, has a thickness (r) of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. In some examples, the supporting structure has a width (v) that is from <NUM> to <NUM>, for example about <NUM> or about <NUM>.

The wiring layer may be formed continuously of the one or more conductive traces and may be comprised of various metals or alloys thereof, for example, copper (Cu), gold (Au), silver (Ag), gold/chromium (Au/Cr), platinum (Pt), platinum/ iridium (Pt/lr), titanium (Ti), gold/titanium (Au/Ti), or any alloy thereof. The wiring layer may have a thickness (x) of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. In some examples, a top surface of the wiring layer is coplanar with a top surface of the supporting structure. In other examples, the wiring layer is embedded within the supporting structure. In yet other examples, the wiring layer is formed on the top surface of the supporting structure and the top surface of the wiring layer is raised above the top surface of the supporting structure.

In some examples, each of the set of electrodes <NUM> is formed on the supporting structure and is in electrical contact with the wiring layer. Each electrode <NUM> may be comprised of conductive material such as copper (Cu), gold (Au), silver (Ag), gold/chromium (Au/Cr), platinum (Pt), platinum/ iridium (Pt/lr), titanium (Ti), gold/titanium (Au/Ti), or any alloy thereof, for example. Each electrode <NUM> may have a thickness (z) of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. The set of electrodes <NUM> may be formed directly on the supporting structure or formed indirectly on the supporting structure. In some examples, a set of contacts are formed on the supporting structure and provide electrical contact between the set of electrodes <NUM> and the wiring layer. The contacts may be comprised of conductive material such as copper (Cu), gold (Au), silver (Ag), gold/chromium (Au/Cr), platinum (Pt), platinum/ iridium (Pt/lr), titanium (Ti), gold/titanium (Au/Ti), or any alloy thereof, for example.

<FIG> shows electrodes arranged in a helical configuration and included within a deep brain stimulation system. <FIG> shows leads arranged in a helical configuration and included within a deep brain stimulation system. As shown, a helical substrate <NUM> is configured in a helical shape around a supporting structure <NUM>. A set of electrodes <NUM> and a set of traces <NUM> can be formed on helical substrate <NUM>. Substrate <NUM> is wrapped such that it forms a helical shape. As used herein, the phrases "helical" refer to a device fabricated with plural helixes or helices, which are a type of smooth space curve, i.e. a curve in three-dimensional space. The helix may be wound clockwise direction or anti-clockwise direction. The helix have the property that a tangent line at any point makes a constant angle with a fixed line called the axis. It will be appreciated that the collective set of electrodes <NUM> and the set of traces <NUM> (and/or each individual trace <NUM>) can also be helically shaped.

Substrate <NUM> may extend along and/or may be helically positioned along a portion of the lead assembly. The portion can include substantially the entire length of the one or more conductive traces and/or of the set of electrodes. Alternatively, the helical portion may be the portion of the cable extending between the proximal end and the distal end but not including the a connecting portion (e.g., that includes bonding pads and/or one or more other connectors). In certain examples, the helical portion of the cable comprises one or more characteristics including a radius, a helix angle, a pitch (rise of the helix for one turn), a helix length, and/or a total rise of the helix. The radius may be from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>, for example, about <NUM>. The helix angle may be from <NUM>° to <NUM>°, from <NUM>° to <NUM>°, or from <NUM>° to <NUM>°, for example, about <NUM>°. A pitch may be from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>, for example, about <NUM>. The helix length may be from <NUM> to <NUM> or <NUM> to <NUM>, e.g., about <NUM>, from the proximal end to the distal end. The total rise may be from <NUM> to <NUM> or <NUM> to <NUM>, e.g., about <NUM>, from the proximal end to the distal end.

In some instances, a characteristic of the helix at a first portion of the lead assembly that includes electrodes <NUM> is different than a characteristic of the helix at a second portion of the lead assembly that includes traces <NUM>. In some examples, the first portion (that supports electrodes <NUM>) has a first helical structure. The first portion may be defined as the last <NUM> to <NUM> of the cable on the distal end of the cable. In certain examples, the first portion comprises tight helixes (e.g., for tissue penetration as with deep brain stimulation or connection to a device such as a neurostimulator) with characteristics including a radius from <NUM> to <NUM>, a helix angle from <NUM>° to <NUM>°, and a pitch from <NUM> to <NUM>. In some examples, the second portion (that supports traces <NUM>) has a second helical structure. In certain embodiments, the second portion comprises loose helixes with characteristics including a radius from <NUM> to <NUM>, a helix angle from <NUM>° to <NUM>°, and a pitch from <NUM> to <NUM>.

In some instances, part or all of the lead assembly further includes a housing that is disposed on, positioned on and/or encases the electrodes and/or leads. The housing may be comprised of a medical grade polymer material. In some examples, the medical grade polymer is thermosetting or thermoplastic. For example, the medical grade polymer may be a soft polymer such as silicone, a polymer dispersion such as latex, a chemical vapor deposited poly(p-xylylene) polymer such as parylene, or a polyurethane such as Bionate® Thermoplastic Polycarbonate-urethane (PCU) or CarboSil® Thermoplastic Silicone-Polycarbonate-urethan (TSPCU).

At a proximal end of the lead assembly, substrate <NUM> can flatten such that it is no longer in a helical shape, as shown in <FIG>. Further, in some instances, supporting structure <NUM> is absent at the proximal end or also is in a flat (non-cylindrical) shape. Each trace <NUM> can terminate at a bonding pad <NUM>. In some instances, bonding pads <NUM> and traces <NUM> include a same material and/or same composition. The lead assembly may be configured such that there is, for example, a <NUM>:<NUM> ratio between traces and bonding pads, or multiple traces <NUM> may connect to an individual bonding pad <NUM>.

<FIG> show stages of manufacture of a lead assembly (e.g., used to manufacture the lead assembly depicted in <FIG> and <FIG>) according to an embodiment of the invention. More specifically, <FIG> illustrate stages during a process for forming a helically shaped substrate, which can support electrical traces and/or electrodes.

As shown in <FIG>, a coating <NUM> can be formed on a mandrel <NUM>. Coating <NUM> can include a material that can facilitate withdrawal of mandrel <NUM> towards the end of the process. For example, coating <NUM> can include a heat shrink tube, a fluoro polymer, polytetrafluoroethylene and/or Teflon, and the heat shrink tube can be recovered at (for example) <NUM>. Mandrel <NUM> can include a rigid material, metal material, and/or fluoro polymer (e.g., polytetrafluoroethylene).

As shown in <FIG>, the mandrel <NUM> can be inserted into a thermoplastic tubing <NUM> (e.g., comprising thermoplastic polyurethane). Thermoplastic tubing <NUM> can include a reflowable material and/or can include (for example) CarboSil tube).

A substrate <NUM> can then be wrapped around thermoplastic tubing <NUM>. ) A first portions <NUM> of substrate can be wrapped to include (for example) regularly spacing between subsequent wraps across the entire mandrel or across each of one or more portions of the mandrel. The substrate can include a thin-film material and/or polymer, such as liquid-crystal polymer (LCP). The wrapped mandrel can then be thermoformed to define the helical shape. While first portion <NUM> of the substrate can be wrapped in a helical portion, a second portion <NUM> can remain planar to support a connector (e.g., a bond pad). First portion <NUM> and second portion <NUM> of the substrate can, but need not, have a same composition and/or thickness.

The wrapped mandrel can then be inserted into a peelable heat-shrink tube (and/or tube including a fluoro polymer) <NUM>. The assembly can then be recovered (e.g., at <NUM>) to shrink the heat-shrink tube. ) The shrunk heat-shrink tube <NUM> can apply pressure to the wrapped mandrel to hold the assembly together. During the heating process, thermoplastic tubing <NUM> can further reflow, which can glue into first portion <NUM> of substrate. The reflow can cause the assembly to have a smoother surface, such that first portion <NUM> of the substrate is not raised relative to thermoplastic tubing <NUM>.

The assembly can then be cooled (e.g. to room temperature), and heat-shrink tube <NUM> can be peeled away. ) Mandrel <NUM> and coating <NUM> can then be removed (<FIG>). As shown in the cross-section illustrated in <FIG>, a resulting lead assembly the includes a stylet lumen <NUM> through a middle portion of the lead assembly. The lead assembly can include a helically wrapped substrate <NUM> and a thermoplastic tubing <NUM> or other supporting structure. The depicted cross section shows substrate <NUM> as extending fully around thermoplastic tubing <NUM>. However, it will be appreciated that - due to the helical nature of the substrate, it may extend across only a portion of the circumference for any given cross-section corresponding to a specific position along the lead assembly's length. A diameter of lumen <NUM> may be (for example) at least <NUM>%, at least <NUM>%, at least <NUM>% or at least <NUM>% of a diameter of the helically wrapped portion of the lead assembly. A diameter of lumen <NUM> may be (for example) less than <NUM>%, less than <NUM>%, less than <NUM>% or less than <NUM>% of a diameter of the helically wrapped portion of the lead assembly.

During an implantation process, a stylet (e.g., a rigid thin object, such as a metallic thin object) can be inserted into stylet lumen <NUM>. The stylet can provide rigidity to the lead assembly to facilitate implanting the device to a target position.

Thus, <FIG> illustrate how a thermoplastic can be used to manufacture a lead assembly that includes a central lumen. In the illustrated example, a thermoplastic tubing is reflowed to essentially glue the helical substrate and an underlying material together, such that a supporting mandrel can be removed. Another approach for manufacturing a lead assembly with a central lumen is to use a thermoset material.

<FIG> show stages of manufacture of a lead assembly using a thermoset material according to an embodiment of the invention. More specifically, <FIG> illustrate stages during a formation of a helically shaped substrate, which can support electrical traces and/or electrodes.

As shown in <FIG>, a coating <NUM> can be applied to a tubing <NUM>. Tubing <NUM> can include (for example) a thermoset material and/or silicone tubing. Coating <NUM> can include (for example) diluted liquid silicone resin. In some instances, coating <NUM> is applied after the surface of tubing <NUM> is prepared for adhesion (e.g., by performing a plasma activation or oxygen plasma activation). After coating <NUM> is applied, the coated tubing can be partially thermally cured (e.g., to a <NUM>-<NUM> thickness). This partial curing can result in a surface of the tubing being tacky.

A mandrel <NUM> can be inserted into the coated tubing. ) Mandrel <NUM> can include and/or can be (for example) a rigid material, metal material, and/or fluoro polymer (e.g., polytetrafluoroethylene). Mandrel <NUM> can include be coated, such as with a fluoro polymer, polytetrafluoroethylene and/or Teflon rigid material, metal material, and/or fluoro polymer (e.g., polytetrafluoroethylene).

A first portion <NUM> of a substrate can then be wrapped around the coated tubing <NUM>. ) In some instances, prior to the wrapping, a surface of first portion <NUM> of the substrate can be prepared for adhesion by (for example) performing a plasma activation (e.g., oxygen plasma activation).

First portions <NUM> of the substrate can be wrapped to include (for example) regularly spacing between subsequent wraps across the entire mandrel or across each of one or more portions of the mandrel. The substrate can include a thin-film material and/or polymer, such as liquid-crystal polymer (LCP). While first portion <NUM> of the substrate can be wrapped in a helical portion, a second portion <NUM> can remain planar to support a connector (e.g., a bond pad). First portion <NUM> and second portion <NUM> of the substrate can, but need not, have a same composition and/or thickness.

The wrapped mandrel can then be inserted into a peelable heat-shrink tube (and/or tube including a fluoro polymer and/or PEELZ) <NUM>. The assembly can then be recovered (e.g., at <NUM>) to shrink the heat-shrink tube. ) The shrunk heat-shrink tube <NUM> can apply pressure to the wrapped mandrel to hold the assembly together. The partially cured coating <NUM> on tubing <NUM> can adhere to the wrapped first portion <NUM> of the substrate due to covalent bonding under heat and pressure, which can fully cure coating <NUM>.

The assembly can then be cooled (e.g. to room temperature), and heat-shrink tube <NUM> can be peeled away. ) Mandrel <NUM> can then be removed (<FIG>).

As shown in the cross-section illustrated in <FIG>, a resulting lead assembly the includes a stylet lumen <NUM> through a middle portion of the lead assembly. The lead assembly can include a helically wrapped substrate <NUM> and a tubing <NUM> that is coated with a coating <NUM> (e.g., a thermoset coating), which can facilitate adhering substrate <NUM> to tubing <NUM>. The depicted cross section shows substrate <NUM> as extending fully around tubing <NUM>. However, it will be appreciated that - due to the helical nature of the substrate, it may extend across only a portion of the circumference for any given cross-section corresponding to a specific position along the lead assembly's length. A diameter of lumen <NUM> may be (for example) at least <NUM>%, at least <NUM>%, at least <NUM>% or at least <NUM>% of a diameter of the helically wrapped portion of the lead assembly. A diameter of lumen <NUM> may be (for example) less than <NUM>%, less than <NUM>%, less than <NUM>% or less than <NUM>% of a diameter of the helically wrapped portion of the lead assembly.

<FIG> show various views of a lead assembly according to an embodiment of the invention. The depicted lead assembly includes one manufactured in accordance with the manufacture illustrated in <FIG>. The lead assembly again includes a proximal section <NUM> that includes multiple bonding pads. The lead assembly further includes a distal section. The distal section includes a first distal-section portion <NUM> (shown in <FIG>) and a second distal-section portion <NUM> (shown in <FIG>), and a middle section that extends between proximal section <NUM> and the distal section and includes a middle-section portion <NUM> (shown in <FIG>).

Across the distal section and middle section, a substrate <NUM> is wrapped in a helically shape. At proximal section <NUM>, substrate <NUM> is in a planar configuration. At the distal section, a set of electrodes <NUM> is disposed on the helically shaped substrate <NUM>. A lumen <NUM> extends through the part of the lead assembly that includes the wrapped substrate <NUM>. Each electrode <NUM> can be connected to an electrical trace <NUM> that extends from the electrode to a bonding pad - in a helical shape - along the middle section (along substrate <NUM>).

As shown in <FIG>, a mandrel <NUM> can be inserted into a silicone tubing <NUM>. (It will be appreciated that, alternatively, a coating can be applied to mandrel <NUM>). Mandrel <NUM> can include and/or can be (for example) a rigid material, metal material, and/or fluoro polymer (e.g., polytetrafluoroethylene). Mandrel <NUM> can include be coated, such as with a fluoro polymer, polytetrafluoroethylene and/or Teflon rigid material, metal material, and/or fluoro polymer (e.g., polytetrafluoroethylene). Silicone tubing <NUM> can have an inner diameter that is (for example) less than <NUM>, less than <NUM>, less than <NUM> and/or approximately <NUM> inches. Silicone tubing <NUM> can have an outer diameter that is (for example) less than <NUM>, less than <NUM>, less than <NUM> and/or approximately <NUM> inches. Mandrel <NUM> can have an outer diameter than is (for example) greater than <NUM>, greater than <NUM>, approximately <NUM>, less than <NUM>, and/or less than <NUM> inches.

As shown in <FIG>, the tubing-mandrel assembly can be inserted into a thermoplastic tubing <NUM> (e.g., comprising thermoplastic polyurethane). Thermoplastic tubing <NUM> can include a reflowable material and/or can include (for example) CarboSil tube. Thermoplastic tubing <NUM> can have an inner diameter that is (for example) less than <NUM>, less than <NUM>, less than <NUM>, approximately <NUM>, greater than <NUM> and/or greater than <NUM> inches. Thermoplastic tubing <NUM> can have an outer diameter that is (for example) less than <NUM>, less than <NUM>, approximately <NUM>, greater than <NUM>, and/or greater than <NUM> inches.

A first portion <NUM> of a substrate can then be wrapped around thermoplastic tubing <NUM>. ) The wrapping can be performed to produce (for example) regularly spacing between subsequent wraps across the entire thermoplastic tubing or across each of one or more portions of the thermoplastic tubing. The substrate can include a thin-film material and/or polymer, such as liquid-crystal polymer (LCP). The wrapped structure can then be thermoformed (e.g., at <NUM>° C) to define the helical shape. While first portion <NUM> of the substrate can be wrapped in a helical portion, a second portion <NUM> can remain planar to support a connector (e.g., a bond pad). First portion <NUM> and second portion <NUM> of the substrate can, but need not, have a same composition and/or thickness.

The wrapped structure can then be inserted into a peelable heat-shrink tube (and/or tube including a fluoro polymer and/or PEELZ) <NUM>. The assembly can then be recovered (e.g., at <NUM>) to shrink the heat-shrink tube. ) The shrunk heat-shrink tube <NUM> can apply pressure to the wrapped mandrel to hold the assembly together. During the heating process, thermoplastic tubing <NUM> can further reflow, which can glue into first portion <NUM> of substrate. The reflow can cause the assembly to have a smoother surface, such that first portion <NUM> of the substrate is not raised relative to thermoplastic tubing <NUM>.

The assembly can then be cooled (e.g. to room temperature), and heat-shrink tube <NUM> can be peeled away. ) Mandrel <NUM> can then be removed (<FIG>). Thus, both thermosetting and thermoforming (e.g., using heat-shrink tube <NUM> and thermoplastic tubing <NUM>, respectively) can stabilize the helical position of first portion <NUM> of the substrate.

As shown in the cross-section illustrated in <FIG>, a resulting lead assembly the includes a stylet lumen <NUM> through a middle portion of the lead assembly. The lead assembly can include a helically wrapped substrate <NUM>, which is wrapped around thermoplastic tubing <NUM>, which is adhered to silicone tubing <NUM>. The depicted cross section shows substrate <NUM> as extending fully around thermoplastic tubing <NUM>. However, it will be appreciated that - due to the helical nature of the substrate, it may extend across only a portion of the circumference for any given cross-section corresponding to a specific position along the lead assembly's length. A diameter of lumen <NUM> may be (for example) at least <NUM>%, at least <NUM>%, at least <NUM>% or at least <NUM>% of a diameter of the helically wrapped portion of the lead assembly. A diameter of lumen <NUM> may be (for example) less than <NUM>%, less than <NUM>%, less than <NUM>% or less than <NUM>% of a diameter of the helically wrapped portion of the lead assembly.

Various designs and processes disclosed herein can facilitate generation of a stimulation system that has a small outer diameter, which can reduce inflammation and damage while implanting the system or while it is positioned at an implant location. In some instances, the stimulation system (e.g., and/or a lead body) can have an outer diameter that is less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, and/or approximately <NUM>. In some instances, the stimulation system can be designed to include a large number of electrodes and traces (e.g., approximately <NUM>, <NUM>, <NUM> or <NUM> electrodes and/or more than <NUM>, more than <NUM>, more than <NUM> or more than <NUM> electrodes) while still having a small outer diameter (e.g., that is less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, and/or approximately <NUM>).

Specific details are given in the above description to provide a thorough understanding of the invention.

Claim 1:
A method of manufacturing a lead assembly comprising:
disposing a set of electrodes (<NUM>) and a set of electrical traces (<NUM>) on an insulating substrate (<NUM>, <NUM>, <NUM>, <NUM>), wherein each of the set of electrodes is connected to an electrical trace of the set of electrical traces;
inserting a mandrel (<NUM>, <NUM>, <NUM>) through a tubing (<NUM>, <NUM>, <NUM>), wherein the tubing includes a thermoset material or a thermoplastic material;
wrapping the substrate (<NUM>, <NUM>, <NUM>) around the tubing such that the substrate is in a helical shape;
inserting the substrate-wrapped tubing and mandrel into a heat-shrink tube (<NUM>, <NUM>, <NUM>);
heating, subsequent to the insertion, the heat-shrink tube, wherein the tubing and the insulating substrate are glued together by reflow when the tubing includes a thermoplastic material or adhered to one another by curing a coating (<NUM>, <NUM>) of the tubing when the tubing includes a thermoset material;
removing the heat-shrink tube from the substrate-wrapped tubing; and
removing the mandrel from the substrate-wrapped tubing.