WO2025178822A1 - Low-profile percutaneously deployable lead array system - Google Patents

Abstract

A lead includes an expandable electrode assembly, which includes a compressible support and is formed from a shape memory material. The support forms an interior volume therein. A flexible membrane is positioned on an exterior surface of the support. An electrode is attached to an outer surface of the flexible membrane. The lead further includes one or more wires passing through the interior volume of the support. Each individual wire of the one or more wires is electrically connected to a different or unique one of each of the one or more electrodes. The electrode assembly is compressible to be placed in a constrained state to fit within a sheath for percutaneous delivery to a region of interest. The electrode is expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath.

Description

LOW-PROFILE PERCUT ANEOUSLY DEPLOYABLE LEAD ARRAY SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Patent Application Serial No. 63/557,002, filed February 23, 2024, the disclosure of which is incorporated herein by reference.

BACKGROUND

[0002] The following information is provided to assist the reader in understanding technologies disclosed below and the environment in which such technologies may typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless clearly stated otherwise in this document. References set forth herein may facilitate understanding of the technologies or the background thereof. The disclosure of all references cited herein are incorporated by reference.

[0003] For a number of reasons, leads, wires or electrodes (for example, titanium or platinum stimulator leads) are implanted within the human body (for example, in connection with the brain, the spinal cord, peripheral nerves, etc.). For example, leads may be implanted to provide therapy for chronic pain. In that regard, a significant percentage of adults suffer from daily chronic pain. Severe pain is associated with worse health and a greater level of disability, and it results in a significant annual economic burden. Pharmaceutical treatments can lead to substance abuse and overdose, which has fueled a devastating opioid epidemic. Therefore, alternative pain treatments such as neurostimulation therapy via spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are often utilized.

[0004] In that regard, patients in severe refractory and chronic pain often elect to have one or more stimulator leads placed along the spinal cord or various peripheral nerves to help with pain control. Both PNS and SCS leads may also be placed for acute pain as well. Upon implanting one or more electrodes near a nerve or the spinal cord, an electrical stimulus may be applied via an implanted pulse generator to modulate the perception of pain. The leads, wires or electrode leads and associated electrodes operatively connected to the implanted pulse generator can modulate pain and improve physical function. Long term pain relief is often achieved even after the cessation of stimulation, and chronic stimulation is not always required to treat chronic pain. The result is an analgesic effect without the use of addictive drugs. Furthermore, SCS and PNS can be used to treat neuropathic and nociplastic pain, which are resistant to opioids.

[0005] SCS therapy is an effective therapy to manage chronic pain including, for example, in patients with back and leg pain after spine surgery, as well as various types of neuropathic pains (see FIG. 1 A). Since the first introduction of SCS devices in the 1970s, two types of leads are widely used (see FIG. IB) - (1 ) minimally invasive “cylindrical” leads and (2) relatively bulky and large “paddle” leads. Such types of leads may also be used in therapies or diagnostic procedures other than SCS. Minimally invasive cylindrical leads require a smaller surgical incision with a local injection of an anesthetic. Then, the leads are delivered percutaneous ly and confirmed using fluoroscopy to assess the device position and migration.

[0006] However, since they are small, cylindrical leads can easily move and migrate, which generates device migration and associated complications that require further surgery. Moreover, at least two leads are typically required to deliver therapy. Also, since the electrodes are small, any small movement of the lead means the electrodes will no longer stimulate the correct or target region (for example, part of the spinal cord to cause pain relief). Percutaneous leads are placed by pain specialists as well as surgeons.

[0007] On the other hand, paddle leads are designed to be more stable and secure than traditional cylindrical leads, to provide a larger surface area for stimulation, and to provide more freedom for programming. Further, paddle leads may be less likely to move or shift once implanted. However, the paddle leads are typically large and bulky with a generally flat insulated electrode. Therefore, a relatively large incision is required to deliver the device. Typically, only surgeons have the necessary skill set to implant paddle leads. Moreover, implantation of a paddle lead for spinal cord stimulation entails removing the “roof” of the spinal canal and the vertebral lamina (laminectomy) to create the necessary space for the lead placement during the device delivery, positioning, and placement (see FIG. 1C).

[0008] The laminectomy required to place paddle leads in SCS is a neurosurgical procedure and a potential destabilizing change, which is associated with acute and chronic complications such as (1) epidural bleeding leading to paraplegia, (2) nerve damage (nerves around the surgical site may be damaged during the procedure), (3) post-laminectomy syndrome, in which patient develops persistent back pain due to laminectomy, (4) spinal instability or “weakening” of the spine (a laminectomy can destabilize the spine, potential ly leading to spina l deformities or chronic pain), (5) scar tissue formation leading to nerve compression and chronic pain, and (6) prolonged recovery period and additional pain after surgery due to larger incision and laminectomy compared to percutaneous technique. Occasionally, there are complications that require removal of stimulator leads. A paddle lead is not easily retrievable and requires a large incision with re-exploration of the surgical site.

[0009] One comparative study showed higher reoperation rates for patients with percutaneous cylindrical lead systems compared to paddle SCS systems at the two-year point and 5+ year points. On the other hand, paddle leads are more invasive and require laminectomy, and revision surgeries to remove paddle leads result in more blood loss, longer surgical times, and need for removal of more bone in more than half of cases. The problem location is multifold - the location of invasive surgical laminectomy is in the operating room, but the complications mentioned above are often experienced by patients at home and then upon presentation in an outpatient clinic.

[0010] One study introduced a paddle-like lead device which can be rolled and delivered through a 14-gauge spinal needle and unrolled after delivery' via embedded micro fluidic channels. The size and electrode patterns of such a device may be limited as a result of the deployment mechanism. Moreover, the device may lack sufficient supportive force to create an ideal wall apposition (that is, pressurized physical contact of the electrode to the wall) after an SCS placement. Such features are important to effectively deliver electric fields from a deployed SCS device regardless of the location in the epidural space and anatomical variations in patients. Moreover, it may be challenging for such rolled electrodes to be repositioned or retrieved if required during or after the procedure.

[0011] It remains desirable to develop improved lead devices for various procedures including, for example, neurostimulation therapy (such as SCS, PNS, etc.).

SUMMARY

[0012] A lead includes an electrode assembly which is expandable. The electrode assembly includes a support which is compressible (that is, configured or functional (for example, flexible, foldable, etc.) to be made smaller ) and is formed from a shape memory material. The support forms an interior volume therein. A flexible membrane is positioned on an exterior surface of the support. An electrode is attached to an outer surface of the flexible membrane. The lead further includes one or more wires passing through the interior volume of the support. Each individual wire of the one or more wires is electrically connected to a different or unique one of each of the one or more electrodes. The electrode assembly is compressible to be placed in a constrained state to fit within a sheath for percutaneous delivery to a region of interest. The electrode is expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath.

[0013] In a number of embodiments, the shape memory material is a shape memory alloy. The shape memory alloy may, for example, be nitinol.

[0014] The flexible membrane may encompasses the circumference of the support along the length thereof. In a number of embodiments, the flexible membrane is elastic. The flexible membrane may be insulating. The flexible membrane may be formed from a polymeric material. In a number of embodiments, the polymeric material is selected from the group consisting of polytetrafluorethylene and polyurethane.

[0015] In a number of embodiments, a plurality of electrodes is attached to the outer surface of the flexible membrane and a plurality of wires pass through the interior volume of the support, wherein at least one of each of the plurality of wires extends to connect to a different or unique one of the plurality of electrodes. Each of the plurality of wires may extend from a proximal end of the support in a configuration to pass through a body in which the lead is to be implanted and connect to electronic circuitry. The electronic circuitry may be implanted or maybe positioned extracorporeally.

[0016] hi a number of embodiments, the support is formed from a tube comprising interconnected lengths or struts formed from the shape memory alloy which is subjected to one or more shaping heat treatment processes to create a paddle-type lead shape in the unconstrained state of the support. The support may be formed to have a determined cross- sectional shape, as determined generally perpendicularly to the axis of the support, over at least a portion of the (axial) length thereof. The determined cross-sectional shape is a crescent shape in a number of embodiments. The tube may, for example, undergo a first shaping heat treatment process to expand the diameter thereof over at least a portion of the length thereof and a second shaping heat treatment process to create the crescent shape. [0017] Each of the one or more electrodes may, for example, be at least partially recessed within an opening formed between extending, interconnected struts of the support.

[0018] In a number of embodiments of a lead hereof (for use, for example, in the epidural space), the self-expanding support is configured to exert a radial force in the range of 0.5-2.0 N/mm. The support may, for example, be designed to expand to a diameter 10-20% larger than the target space (for example, the epidural space), ensuring secure apposition and effective electrode contact, as well as preventing device migration.

[0019] A system includes a lead including an electrode assembly which includes a support, which is compressible and is formed from a shape memory material, the support forming an interior volume therein, a flexible membrane on an exterior surface of the support, and one or more electrodes attached to an outer surface of the flexible membrane. The lead further includes one or more wires passing through the interior volume of the support. Each individual wire of the one or more wires is electrically connected to a different or unique one of each of the one or more electrodes. The electrode assembly is compressible to a constrained state to fit within a sheath for percutaneous delivery' to a region of interest and expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath. The system further includes electronic circuitry in electrical connection with the one or more wires. The electronic circuitry is configured to transmit electrical signals between the one or more electrodes and the electronic circuitry via the one or more wires.

[0020] As described above, the shape memory material may be a shape memory alloy. The shape memory alloy may, for example, be nitinol.

[0021 ] The flexible membrane may encompasses the circumference of the support along the length thereof. In a number of embodiments, the flexible membrane is elastic. The flexible membrane may be electrically insulating. The flexible membrane may be formed from a polymeric material. In a number of embodiments, the polymeric material is selected from the group consisting of polytetrafluorethylene and polyurethane.

[0022] In a number of embodiments, a plurality of electrodes is attached to the outer surface of the flexible membrane and a plurality of wires pass through the interior volume of the support, wherein each of the plurality of wires extends to connect to a different or unique one of the plurality of electrodes. Each of the plurality of wires may extend from a proximal end of the support in a configuration to pass through a body in which the lead is to be implanted and connect to electronic circuitry. The electronic circuitry may be implanted or may be positioned extracorporeally.

[0023] In a number of embodiments, the support is formed from a tube comprising interconnected lengths or struts formed from the shape memory alloy which is subjected to one or more shaping heat treatment processes to create a paddle-type lead shape in the unconstrained state of the support. The support may be formed to have a determined cross- sectional shape, generally perpendicular to the axis of the support, over at least a portion of the axial length of the support. In a number of embodiments, the cross-sectional shape generally perpendicular to the axis of the support over at least a portion of the length thereof is a crescent shape. The tube may, for example, undergo a first shaping heat treatment process to expand the diameter thereof over at least a portion of the length thereof and a second shaping heat treatment process to create the crescent shape.

[0024] In a number of embodiments, each of the one or more electrodes is at least partially recessed within an opening formed between extending, interconnected struts of the support.

[0025] In a number of embodiments (for example, in case of a lead for use in the epidural space), the self-expanding support is configured to exert a radial force in the range of 0.5-2.0 N/mm. The support may, for example, be designed to expand to a diameter 10-20% larger than the target space (for example, the epidural space), ensuring secure apposition and effective electrode contact, as well as preventing device migration.

[0026] A system includes a lead including an electrode assembly which is expandable. The electrode assembly includes a support which is compressible and is formed from a shape memory material. The support forms an interior volume therein. A flexible membrane is positioned on an exterior surface of the support. The lead further includes one or more electrodes attached to an outer surface of the flexible membrane. One or more wires pass through the interior volume of the support. At least one of the one or more wires is electrically connected to a different or unique one of each one or more electrodes. The electrode assembly is compressible to a constrained state to fit within a sheath for percutaneous del i very to a region of interest and expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath. The system may further include a hollow needle through which the sheath passes.

[0027] A method of implanting a lead includes compressing an electrode assembly of the lead hereof to a constrained state within a generally cylindrical sheath, percutaneous delivering the lead within the generally cylindrical sheath to a region of interest, and removing the lead from the generally cylindrical sheath so that the expandable lead expands to an unconstrained state. The sheath may, for example, be passed through a hollow needle. The lead may, for example, be implanted for a diagnostic purpose or for a therapeutic purpose. In a number of embodiments, the lead is implanted to deliver electric signals in a therapeutic procedure. The therapeutic procedure may, for example, be pain relief. In a number of embodiments, the region of interest is the epidural space and the therapeutic procedure is spinal cord stimulation.

[0028] The present devices, systems, and methods, along with the attributes and attendant advantages thereof, will best be appreciated and understood in view of the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 A is an X-ray image illustrating a mechanism of spinal cord stimulation therapy using leads.

[0030] FIG. IB illustrates a representative embodiment of a commercially available cylindrical lead and a representative embodiment of a commercially available paddle lead.

[0031] FIG. IC is an X-ray image illustrating leads placed in an appropriate position for SCS.

[0032] FIG. 2A illustrates schematically an embodiment of an expandable or unconstrained, paddle-shaped lead hereof in a delivery sheath and upon expansion/ deployment after retraction of the sheath.

[0033] FIG. 2B illustrates schematically a cutaway view of the lead of FIG. 2A show a crescent shape of the lead.

[0034] FIG. 3A illustrates schematically a posterior view of another embodiment of an expandable lead hereof including an expandable shape memory alloy (for example, nitinol) support or backbone and an electrode array supported upon a membrane covering the support, wherein the lead is deployed within the epidural space of the spine.

[0035] FIG. 3B illustrates schematically a system including the lead of FIG. 3 A and electronic circuitry in connection therewith, wherein the lead is deployed within the epidural space of a model of the spine (illustrated in a lateral view).

[0036] FIG. 3C illustrates a schematic, cross-sectional view the lead of FIG. 3 A deployed in the epidural space.

[0037] FIG. 3D illustrates a schematic, cross-sectional view of two commercially available cylindrical leads deployed in the epidural space.

[0038] FIG. 3E illustrates a schematic, cross-sectional view of a commercially available paddle lead deployed in the epidural space.

[0039] FIG. 4 A illustrates a top view photograph another embodiment of a lead hereof and components thereof in which the support or backbone is formed from a laser-cut, generally cylindrical, stent-like component.

[0040] FIG. 4B illustrates a prospective view photograph of the lead of FIG. 4A and the support thereof in both a raw (cylindrical stent) and shaped form.

[0041] FIG. 4C illustrates schematically an embodiment of a paddle-shaped lead hereof wherein the electrodes are positioned in openings between intersecting structs of the support and wherein force was applied to the electrode and underlying membrane to embed or recess (at least partially) the electrode in a slight depression created by deformation of the membrane as represented by the broken lines in the enlarged section of FIG. 4C.

[0042] FIG. 4D illustrates a top photograph of the paddle-shaped lead of FIG. 4A adjacent to a commercially available paddle-shaped lead.

[0043] FIG. 5 A illustrates schematically a top view of various states of deployment of the lead of FIG. 4A.

[0044] FIG. 5B illustrates schematically and in cross section various states of retrieval of the lead of FIG. 4A. [0045] FIG. 6 A illustrates use of a mandrel during heat treatment to increase the diameter of a raw stent-like structure in forming a backbone or support of a lead hereof.

[0046] FIG. 6B illustrates two cylinders used to give the support a crescent-shaped, cross- sectional shape.

[0047] FIG. 6C illustrates use of the two cylinders of FIG. 6B to shape the support during heat treatment.

[0048] FIG. 6D illustrates the support after diameter expansion heat treatment and crescentshaping heat treatment.

[0049] FIG. 7 illustrates a section of an embodiment of a laser-cut support hereof in an expanded state.

[0050] FIG. 8A illustrates a section of an embodiment of a laser-cut cylindrical stent for use in forming a support hereof.

[0051] FIG. 8B illustrates the section of a support formed from the cylindrical stent of FIG. 8 A in an expanded state.

[0052] FIG. 9 illustrates numerical calculations used for a number of embodiments of support structures and paddle-shaped leads hereof to determine if the lead can be folded, compressed or constrained for implantation within a 14 Ga needle (inner diameter of 1.6mm).

[0053] FIG. 10A illustrates results of three-point bending mechanical tests performed on the support of the device of FIG. 4A.

[0054] FIG. 10B illustrates results of mid-line crush resistance mechanical tests performed on the support of the device of FIG. 4 A.

[0055] FIG. 10C illustrates results of side-line crush resistance mechanical tests performed on the support of the device of FIG. 4 A.

[0056] FIG. 11 illustrates impedance recording (magnitude) studies of an embodiment electrodes hereof. [0057] FIG. 12 illustrates impedance recording (phase) studies of the electrodes studied in connection with FIG. 11.

[0058] FIG. 13 illustrates cyclic voltammetry studies of the electrodes studied in connection with FIG. 13.

[0059] FIG. 14 illustrates a comparison of electrical resistivity of the electrode/wire materials (stainless steel, platinum/iridium alloy, and an electrode material of a commercially available lead).

[0060] FIG. 15 illustrates a study of resistance force during deployment of the bare support of the device of FIG. 4A.

[0061] FIG. 16A illustrates a system for conducting mechanical bending tests.

[0062] FIG. 16B illustrates a system for conducting mechanical mid-line crushing tests.

[0063] FIG. 16C illustrates a system for conducting mechanical side-line crushing tests.

DETAILED DESCRIPTION

[0064] It will be readily understood that the components of the embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations in addition to the described representative embodiments. Thus, the following more detailed description of the representative embodiments, as illustrated in the figures, is not intended to limit the scope of the embodiments, as claimed, but is merely illustrative of representative embodiments.

[0065] Reference throughout this specification to “one embodiment” or “an embodiment” (or the like) means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” or the like in various places throughout this specification are not necessarily all referring to the same embodiment.

[0066] Furthermore, described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that the various embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, et cetera. In other instances, well known structures, materials, or operations are not shown or described in detail to avoid obfuscation.

[0067] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a wire” includes a plurality of such wires and equivalents thereof known to those skilled in the art, and so forth, and reference to “the wired” is a reference to one or more such wires and equivalents thereof known to those skilled in the art, and so forth. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value, as well as intermediate ranges, are incorporated into the specification as if individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contraindicated by the text.

[0068] The terms “electronic circuitry,” “circuitry” or “circuit," as used herein include, but are not limited to, hardware, firmware, software, or combinations of each to perform a function(s) or an action(s). For example, based on a desired feature or need, a circuit may include a software controlled microprocessor, discrete logic such as an application specific integrated circuit (ASIC), or other programmed logic device. A circuit may also be fully embodied as software. As used herein, “circuit” is considered synonymous with “logic.” The term “logic,” as used herein includes, but is not limited to, hardware, firmware, software, or combinations of each to perform a function(s) or an action(s), or to cause a function or action from another component. For example, based on a desired application or need, logic may include a software controlled microprocessor, discrete logic such as an application specific integrated circuit (ASIC), or other programmed logic device. Logic may also be fully embodied as software.

[0069] The term “processor," as used herein includes, but is not limited to, one or more of virtually any number of processor systems or stand-alone processors, such as microprocessors, microcontrollers, central processing units (CPUs), and digital signal processors (DSPs), in any combination. The processor may be associated with various other circuits that support operation of the processor, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read only memory (EPROM), clocks, decoders, memory controllers, or interrupt controllers, etc. These support circuits may be internal or external to the processor or its associated electionic packaging. The support circuits are in operative communication with the processor. The support circuits are not necessarily shown separate from the processor in block diagrams or other drawings.

[0070] The term “controller,” as used herein includes, but is not limited to, any circuit or device that coordinates and controls the operation of one or more input and/or output devices. A controller may, for example, include a device having one or more processors, microprocessors, or central processing units capable of being programmed to perform functions.

[0071] The term “software,” as used herein includes, but is not limited to, one or more computer readable or executable instructions that cause a computer or other electronic device to perform functions, actions, or behave in a desired manner. The instructions may be embodied in various forms such as routines, algorithms, modules, or programs including separate applications or code from dynamically linked libraries. Software may also be implemented in various forms such as a stand-alone program, a function call, a servlet, an applet, instructions stored in a memory, part of an operating system or other type of executable instructions. It will be appreciated by one of ordinary skill in the art that the form of software is dependent on, for example, requirements of a desired application, the environment it runs on, or the desires of a designer/programmer or the like.

[0072] To address the limitations of currently available leads described above, devices, systems, and methods hereof include a low-profile, paddle-like or paddle-shaped lead which is readily deployable and retrievable. Although the leads hereof are described in connection with the representative use of SCS, one skilled in the art will appreciate that the leads hereof maybe used in connection with any procedure (whether diagnostic or therapeutic and whether to transmit electrical signal to tissue, to receive electrical signals from tissue, or to both transmit and receive such electrical signals) in which it is desirable to implant a lead within a body (for example, for use in PNS etc.). Examples of regions of interest for use of leads hereof include, for example, the spine, the brain, the peripheral nervous system, the heart, the liver, or other internal organs or tissue, etc. Moreover, new uses of electrical stimulation are currently being developed outside of pain management in treatment of, for example, gastrointestinal disorders, cardiac arrhythmias, seizure treatment or prevention, motor restoration after paralysis, etc. In other words, the stimulator device, systems, and methods hereof may provide options outside of purely pain management indications. [0073] The devices, systems, and methods hereof facilitate effective, minimally invasive procedures via a deployable and retrievable structure. In that regard, the low-profile collapsibility of leads hereof provides the minimally invasive delivery of the leads. After a smooth, minimally invasive delivery through, for example, a 14-gauge or less spinal needle, leads hereof are deployed via self-expansion to occupy a determined volume to provide a large contact area (for example, to occupy a volume in the epidural space, providing reliable pressurized contact between the lead and epidural wall). The devices, systems, and methods hereof facilitate the development of novel and effective solutions for electrical stimulation systems with minimally invasive device delivery and pressurized large area contact to enhance electrical stimulation.

[0074] As described above, when used in connection with SCS systems, paddle lead implantation surgery is a technical procedure that can only be performed by spine surgeons, and is associated with higher costs of care, as well as exposure to additional risks like general anesthesia that a percutaneous technique does not require. In a number of embodiments hereof, expandable or self-expanding lead arrays hereof, which may provide the benefits of a paddle lead, can be collapsed or folded into a collapsed state that is, for example, smaller than a needle and its delivery sheath. A14 Ga needle, for example, has an inner diameter 1.5-1.6mm. The lead array hereof (that is a lead including an array of electrodes), in its collapsed state, can be deployed (for example, within the epidural space) percutaneously from within the lumen of, for example, a 14 Ga or smaller needle.

[0075] FIGS. 2A and 2B illustrates embodiments of a system hereof including a device, lead device or lead 10 including an expandable electrode assembly 12. FIG. 2A illustrates lead 10 in a compressed or constrained state within a delivery sheath 100 and in an expanded or unconstrained state upon retraction of sheath/needle 100. In the illustrated embodiment of FIG. 2A and 2B, lead 10 includes electrode assembly 12 which includes an expandable backbone or support 20. Support 20 includes interconnected extending elements 22 or struts as further discussed below. A relatively thin membrane 30 of an insulating material is positioned on support 20. Electrodes 40 are connected to an upper surface of membrane 30. In the case that the support is electrically conductive, membrane 30 may be insulating and function to electrically isolate electrodes 40. Moreover, membrane 30 assists in limiting tissue growth onto or ingrowth/entanglement into the structure of support 20 which may be a mesh structure as described further below. In addition to other benefits as known in the medical arts, limiting tissue entanglement facilitates retrieval of device 10 if required.

[0076] The membrane material is biocompatible, flexible/foldable, and has suitable strength or modulus to enable membrane 30 to be formed thin (which facilitates folding or collapsing of electrode assembly 12 of lead 10 for delivery via a delivery sheath within, for example, a 13Ga or 14Ga hollow needle). In a number of embodiments, membrane 30 was formed from flexible or elastic polymeric materials such as an expanded polytetrafluoroethylene (ePTFE) or a polyurethane. Tire average thickness/thickness of membrane 30 may, for example, be desirably determined or chosen to be relatively thin to enable electrode assembly 12 to assume the constrained state within the delivery sheath. A suitable Young’s or elastic modulus for the material of membrane 30 may, for example, be determined for a given thickness of membrane 30 based upon stresses experienced in a given use. The material for membrane 30 should also not interfere with the compression and expansion of electrode assembly 12. In a number of embodiments hereof, an ePTFE material was used which had a thickness of 0.02 mm or 20 pm. The ePTFE material exhibited anisotropic elastic moduli which were determined via a standard tensile tests in different directions (X and Y). In a number of studies, the ePTFE material exhibited an elastic modulus in the X direction of 2.7 MPa and an elastic modulus in the Y direction of 324Kpa.

[0077] A plurality of wires 52 (see right side of FIG. 2A, illustrating the expanded/unconstrained state), which may be positioned within a flexible conduit 50 extending from lead 10 to electronic circuitry 200, extends through an internal volume of support 20 of electrode assembly 12 to from an electrical connection with electrodes 40. In a number of embodiments, wires 52 (at a proximal end thereof) are in electrical connection with electronic circuitry 200 (which may be implanted or be external to the body) to provide electrical signals in a controlled manner to electrodes 40, which are in electrical connection with a distal end of wires 52 (in the embodiment of system 300 illustrated in FIG. 2A). Each wire 52 extends through an internal volume of lead 10 created by expanded support 20 and membrane 30 and may pass through membrane 30 to form electrical connection with an associated electrode 40 (see FIGS. 2A and 2B).

[0078] As illustrated in FIGS. 2A and 2B, electrode assembly 12 expands to an unconstrained stated upon removal from a delivery sheath therefor. In the unconstrained state, electrode assembly 12 assumes a paddle-type lead shape. In that regard, electrode assembly 12 expands to have a maximum width greater than flexible conduit 50 and greater than the inner diameter of the delivery sheath/needle. In that regard, in a number of embodiments hereof, electrode support assembly 12 expands to have a maximum width greater than 1.6mm (that is, greater than the inner diameter of a 14 Ga delivery sheath/needle), greater than 2.5mm, greater than 5mm, greater than 10mm, or greater than 15mm.

[0079] As known in the art, electronic circuitry' 200 may include a processor system and a memory system in communicative connection therewith. Processor system and memory system are in communicative connection with a power system (for example, a battery system/rechargeable battery system) to provide power for operation of electronic circuitry 200 and for transmission of electrical signals in a controlled manner to electrodes 40 via associated wires 52. One or more software-based algorithms executable by the processor system may be stored in the memory system to effect control of electrical signals provided to electrodes 40 to provide various therapies. An interface system as known in computer and control arts may be provide for interface with a user. A communication system may be provide for use in, for example, remote access. Data communication via interface system and communication system may be in a wired or wireless manner.

[0080] FIGS. 3 A through 3C illustrates schematically a representative embodiment of a lead 10a suitable for use in SCS and other diagnostic and/or treatment methodologies. Lead 10a was designed, fabricated, and tested in vitro. Support 20a was formed from interconnected extending lengths or elements 22a of a shape memory material such as shape memory alloy. Certain polymers may provide shape memory. However, shape memory metal alloys can provide improved material properties for a given weight and thickness. Extending lengths or elements 22a of the representative shape memory alloy nitinol (a metal alloy of nickel and titanium) and having a thickness or diameter of 230 pm was used in a number of studied embodiments. A microlaser spot welding was use in connecting intersecting extending lengths or element 22a of nitinol in forming backbone or support 20a in a tubular mesh-like structure. Tire welded structure was thermally treated to achieve the desired shape as further discussed below. Individual wires (not shown in FIGS. 3A through 3C) were connected to twelve electrodes 40a in a number of embodiments (formed in an array of three rows of four electrodes 40a in each row upon membrane 30a). Membrane 30a was formed from ePTFE in a number of studied embodiments. In a number of embodiments, in forming expandable electrode assembly 12a of lead 10a, a sheet of polymeric material for membrane 30a was wrapped around support 20a (and other supports hereof) and glued to encompass at least a portion of the axial length of support 20a. In a number of embodiments, membrane 30a encompasses the entire length of support 20a (and other supports hereof). Membrane 30a may also enclose the end portion of support 20 (and other supports hereof).

[0081] FIGS. 3D through 3E illustrate cross-sectional view of the lead or device, two commercially available cylindrical leads 5, and a commercially available paddle lead 5’, respectively deployed in the epidural space. The arced or crescent-shaped cross-sectional confirmation of lead 10a hereof is designed specifically for the epidural space as discussed further below.

[0082] FIGS 4A through 4C illustrate another embodiment of a lead 10b hereof in which support 20b was formed from a laser-trimmed mesh nitinol structure to function as a deployable backbone for lead 10b. An ultrathin ePTFE membrane 30b isolated conductive support or backbone 20b from the electrodes 40b. In a number of studied embodiments, electrodes 40b (which were attached to membrane 30b via an adhesive) were platinum or platinum/iridium strips with the thickness of 0.1 mm and an area of, for example, 10 mm². Copper, stainless-steel, or platinum/iridium wires 52b with the diameter of 0.075mm, which were insulated with an ultrathin layer of polytetrafluoroethylene (PTFE), were used to integrate external electronic circuitry 300 (including a battery pack as the power supply) with electrodes 40b for efficient, controlled electrical signal delivery. In a number of embodiments, both electrodes 40b and the wires 52b are formed form a platinum-iridium (Pt-Ir) alloy.

[0083] As, for example, illustrated in FIGS. 4A and 4B, a generally cylindrical tube 15b, which is similar to a stent, is first formed in a microlaser cutting process. As described further below, in a number of embodiments, tube or stent 15b is expanded (to form expanded cylinder 17b) and subsequently shaped in one or more heat treatment processes to form support 20b. As described above, after expansiow'shaping of support 20b, membrane 30b is placed in connection with support 20b. Electrodes 40b were connected (for example, glued) to an outer surface of membrane 30b, and each of wires 52b was placed in electrical connection with one of electrodes 40b through membrane 30b. Electrodes 40b may, for example, be mounted onto the surface of membrane 30b to position the struts of support 20b to tightly shield the corners of electrodes 40b. [0084] FIG. 4C illustrates schematically an embodiment of a paddle-shaped lead 10b’ hereof wherein electrodes 40b’ are positioned within the diamond-like shapes between intersecting struts 22b’ of support 20b’ to shield the electrodes. Force may be applied to each electrode 40b’ and underlying membrane 30b’ to at least partially embed or recess each electrode 40b’ in a depression created by deformation of flexible membrane 30b’ (within the diamond-shape opening formed by the intersecting struts) as represented by the broken lines in the enlarged section of FIG. 4C. The electrode(s) 40b’ may be recessed to a degree (which may be slight) to provide protection thereof while still providing for contact or electrical connection with target tissue.

[0085] FIG. 4D illustrates a photograph of the paddle-shaped lead 10b adjacent to commercially available paddle-shaped lead 5 ’ . The side-by-side comparison with a commercially available paddle-shaped lead demonstrates that lead 10b and other leads hereof may provide the same or very similar conformation as currently available paddle leads, thereby providing the functional benefits thereof as compared to cylindrical leads. However, unlike conventional paddle-type leads, lead 10b and other leads hereof can deployed and removed/retrieved percutaneously, through a cylindrical delivery system such as a hollow needle/sheath 100b (see, for example, FIG. 5 A), thereby avoiding the significant open surgery required with current paddle-type leads (and associated problems) during deployment and removal thereof. Expandable supports hereof, which may, for example, utilizing a shape memory alloy backbone or support and a precise, patterned design, enable devices hereof to retain structural integrity and functionality after being deployed from, for example, a 14-gauge needle. In various studies of representative device 10b, no signs of disconnection or tearing were observed on the device’s surface, demonstrating its durability and robustness. Deployment and retrieval studies confirmed that the quality of the device remained uncompromised following deployment and retrieval.

[0086] In that regard, FIG. 5 A illustrates schematically consecutive states or stages (1) through (6) of deployment of lead 10b of FIG. 4A from a hollow needle delivery sheath 100b. During deployment, electrode assembly 12b of lead 10b starts in a generally cylindrical, folded, compressed, constrained, or reduced volume form within sheath or needle 100b for percutaneous delivery. Once advanced to a region of interest (for example, through the epidural space), one may pull back upon or retract needle 100b to allow lead 10b to exit needle 100b and to allow electrode assembly 12b to return to its deployed, expanded, or unconstrained form (via expansion of support 20b; see state (6) of FIG. 5 A) such that electrode assembly 12b takes the form of and functions as a paddle-type lead electrode assembly with, for example, a plurality or array of electrodes 40b on a surface thereof. If, at any point after deployment, there is a need for any reason to remove lead 10b or other leads hereof, one can potentially pull lead 10b back into sheath/needle 100b which may, for example, remain dormant in the epidural space. Upon pulling lead 10b in back or in the proximal direction, electrode assembly 12b of lead 10b (and other electrode assemblies hereof hereof) will refold, compress or be constrained to a generally cylindrical, low-volume form within sheath 100b as illustrated in the sequential retrieval or compressing states illustrated in FIG. 5B.

[0087] FIGS. 6A through 6D illustrate the formation of support 10b from a microlaser cut tube. As illustrated in FIG. 6A, a mandrel 400 may be used during a heat treatment process to increase the diameter and shape a raw, stent-like, tubular structure 15b during the formation of backbone or support 20b. During such a heat treatment process, the assembly of raw tube 15b and mandrel 400 is heated in a furnace at a suitable temperature (at or above a shape memory heat treatment temperature for the material, for example, at or above 500 °C) for a period of time (for example, 30 minutes) to set an increased diameter (forming a cylindrically shaped, intermediate tube 17b for support 20b) over at least a portion of its length. FIG. 6B illustrates two cylinders 420 and 422 used to give support 20b a crescent-like, cross-sectional shape. FIG. 6C illustrates the use of two cylinder 420 and 422 of FIG. 6B to shape support 20b during a heat treatment process as described above. In that regard, smaller diameter cylinder 422 (which may be a solid cylinder) is placed within hollow, larger diameter cylinder 420 to form a crescent shape void therebetween. Shaped cylindrical mesh 17b from the heat treatment process with mandrel 400 is placed in that void and undergoes heat treatment to provide support 20b in the (deployed, relaxed or unconstrained) shape illustrated in FIG. 6D (which illustrates support 20b after diameter expansion heat treatment and crescent-shaping heat treatment). An arced or crescent shape or conformation mimics the shape of, for example, the epidural space.

[0088] As described above, during implantation, support 20b structure collapses into a compact cylindrical shape, enabling it to fit within, for example, a 14-gauge Tuohy or smaller needle 100b for relatively seamless insertion into the target site (see FIGS. 5A and 5B). After deployment, device or lead 10b reverts to its original configuration. That transformation results in a paddle-like shape that optimizes the surface area in contact with the spinal cord, enhancing the device's functionality. The ability to collapse and expand relatively seamlessly, and an optimized contact configuration with the target area or region, provide significant advantages of devices hereof compared to other, commercially available paddle-like electrode devices. In the case of the epidural space, if support 20b were flat, the lateral edges would be “floating” in the epidural space, which occurs with commercially available paddle leads (see FIG. 3E). Support 20b hereof may, for example, abut against the dura or the edge of the thecal sack. Moreover, radial forces in lead 10b after implantation may assist in minimizing or preventing migration. Other cross-sectional shapes may be desirable for other regions of interest and are readily achieved in devices hereof via, for example, one or more heat treatment processes.

[0089] As, for example, illustrated in a comparison of support 20b and lead 10b in FIGS. 4A and 4B, support 20b was formed in a number of embodiments to have a tapered proximal end and either a generally straight or tapered distal end. The embodiment in which support 20b has a tapered distal end is illustrated in the fully assembled lead 10b in each of FIGS. 4 A and 4B. Tapered proximal end assists in retracting lead 10b (and other leads hereof) into sheath or needle 100b in case removal is necessary or desired. Clinically, either a tapered or straight distal end should functionally equally well. A tapered distal end may reduce the risk of damaging or irritating tissue. In either cases, the ends of extending lengths or elements 22b of the mesh of support 20b may be bent or rolled inward (toward the interior of support 20b) at the proximal end thereof to eliminate sharp endpoints.

[0090] FIGS. 7 through 8B illustrates a section of several different embodiments of a laser-cut sand expanded supports 20b, 20c, 20d and 20e hereof. FIGS. 8 A and 8B illustrate expanded support 20c and raw, cylindrical stent 15c prior to formation of support 20 as described herein. Various aspects, such as the overall length, overall diameter, the size of openings 24b, 24c formed by interconnected elements, struts or lengths 22b, 22c, strut thickness, etc. may be customized for design considerations such as the region of interest for deployment and the size and number of the electrodes (not shown) to be supported in the assembled lead. As also illustrated in FIGS. 8A through 8B, holes 26c can be provided at the intersections 25c of interconnected elements or lengths 22c to facilitate passage of wires (not shown in FIGS. 8 A and 8B) therethrough for connection to the supported electrodes.

[0091] FIG. 9 illustrates numerical calculations used for several embodiments of support structures and paddle-shaped leads hereof to determine if the lead could be folded, compressed or constrained for implantation within, for example, a 14Ga sheath. The calculations provided confirmation that all studied embodiments could readily be delivered via a 14Ga sheath.

[0092] Various mechanical tests were conducted to evaluate the performance of the devices or leads hereof after deployment. As described above, once deployed, a device or lead hereof should return to its original shape, which is an important step for ensuring its effectiveness when positioned in a target region (for example, adjacent the spinal cord for stimulation thereof in SCS). The transformation from a collapsed cylindrical shape to, for example, the arced or crescent-shaped cross-section of representative embodiments hereof enhances the device’s ability to provide broader coverage over the target region (for example, resulting in more uniform and effective stimulation). Upon implantation, the superelastic properties of, for example, a shape memory alloy such as nitinol used in supports hereof provide mechanical stability, ensuring that the device hereof maintains its intended shape and position within the spinal cord without kinking or deforming. As described below, the results of the mid-line and side-line crushing tests confirmed that the mechanical properties of supports hereof align with the functional requirements of the lead or device. Furthermore, after conducting both bending and crushing tests, no changes or variations in the support structure were observed. In other words, the support demonstrated its ability to retain its shape after being subjected to various loading scenarios in, for example, the spinal cord epidural space.

[0093] To assess the mechanical performance of leads or devices hereof, a series of tests were performed to evaluate their stability and structural integrity under conditions simulating those the leads would experience during and after implantation. Such evaluations are important for understanding the lead’s behavior under various loading scenarios.

[0094] An important aspect of the analysis involved examining the device’s response to bending. The mechanical behavior under bending stress was thoroughly assessed to ensure support 10b maintained its structural integrity and functionality without failure (see FIG. 10A). The results indicated a roughly linear relationship between force and displacement. In a three- point bending test, a displacement of 3 mm was achieved by applying a force of 0.17 N while support 10b was stabilized by supports placed at both ends. The performance demonstrates the capacity of support 10b to endure flexural stress without compromising its design.

[0095] Additionally, it was verified that the shape memory alloy used in support 20b and other supports hereof provided sufficient strength for device 10b to return to its paddle-like configuration after being collapsed and inserted into, for example, a 14-gauge Tuohy needle 100b. In a number of studies, crushing tests were conducted, focusing on the crescentshaped cross-section of support 10b. For successful self-expansion, support 10b should exert sufficient force to push back the surrounding fatty tissue, particularly from the sides, while also achieving adequate expansion at the mid-line for complete coverage.

[0096] The results of crush tests, illustrated in FIGS. 10B and 10C, demonstrated that a 3 mm displacement at the mid-line generated a resistance force of 0.2 N. That force, applied over a small surface area, is sufficient to generate significant stress, effectively displacing the surrounding fatty tissue. A similar response was observed for a side-line crushing study, wherein a resistance force of 2N was measured. That resistance force demonstrates the ability of support 20b to expand laterally during deployment and to maintain the desired configuration post-deployment.

[0097] In a number of representative embodiments of devices hereof, a platinum/Iridium alloy was chosen for electrodes because of its exceptional electrical properties, long-term stability, and good performance in spinal cord stimulation. Platinum/Iridium alloys are resistant to corrosion and degradation in the body’s environment, ensuring that the electrodes remain stable and functional over extended periods. The alloy also exhibits low electrical resistance, minimizing power loss and enhancing signal efficiency, which is desirable for effective electrical stimulation. Electrical Impedance Spectroscopy (EIS) confirmed that the material performs well within the frequency range typically used in conventional spinal cord stimulation (40-60 Hz), showing low resistance, making it a good choice for applications of devices, systems, and methods hereof. Additionally, Cyclic Voltammetry (CV) tests revealed the material’s ability to sustain repeated electrochemical reactions with negligible changes, supporting its long-term durability. The broad potential window from -0.8 V to 0.6 V further confirms the material's versatility, making devices hereof suitable for operation across a range of stimulation voltages.

[0098] As described above, to thoroughly characterize the electrical behavior of representative device 10b, several tests were conducted, with a focus on both the functionality and stability of electrodes 40b. The impedance-frequency curve indicates that this material has the favorable electrical behavior needed for spinal cord stimulation. Given that conventional SCS operates at moderate frequencies (40-60 Hz), the material’s low impedance within this range suggests efficient signal transmission and reduced power requirements (see FIGS. 11 and 12). In addition to EIS, CV was performed to gain deeper insights into the electrochemical properties of the electrodes. This technique allowed measurement of the charge storage capacity (CSC) of electrodes 40b, which is an important factor in determining their ability to deliver effective stimulation pulses. To perform CV test, 10 cycles were performed to ensure the recording had stabilized. The results from CV tests revealed stable peaks over 10 cycles, showing that selected material can sustain repeated electrochemical reactions with neglectable changes (see FIG. 13). Additionally, the stability of the performance in a broad potential window from -0.8 V to 0.6 V, indicates the ability of the material for operating across a range of voltages, which is useful for stimulation. A comparison of the electrical resistivity of different electrode materials showed that stainless steel had approximately 300% higher resistance in comparing the platinum/iridium electrodes hereof and those of a commercial device (see FIG. 14).

[0099] The resistance force during deployment of the device is of significant importance. As a collapsible device, the resistance encountered during deployment can significantly impact the quality of the deployment procedure. To evaluate that force, studies were performed with deployment of support 20b only from a 14 Ga needle 100b, and the resistant force generated during the deployment of support 20b (resulting from its collapsible nature) were measured. The resistance force as a function of the deployed length of bare support 20b is set forth in FIG 15. The results indicate that, as a larger percentage of the backbone is deployed, the pushing force required (or resistance force) decreases. That decreasing trend is attributed to the reduced length of support 20b remaining inside needle 100b, which results in a lower overall radial force exerted on the inner surface of needle 100b.

[00100] The devices, systems, and methods hereof addresses challenges of invasive delivery and post-implantation retrieval of paddle-like electrodes or leads. In general, the devices hereof a relatively readily deployed and retrieved. Further, the devices hereof are readily formed to present a desirable (for example, conforming) shape for use in connection with a target region (for example, a crescent cross-sectional shape with a generally flat insulated platform for the electrode array attachment for use in the epidural space). The devices hereof may, for example, be delivered in a compact cylindrical form, minimizing invasiveness during the implantation process. Once deployed, the device expands to cover the target area (such as the spinal cord) to, for example, achieve effective stimulation or diagnosis while maintaining the ability to be retrieved if necessary. While the area covered by devices hereof is generally the same as, for example, commercially available paddle-shaped SCS devices, device hereof provide better coverage on the spinal cord as a result of the inner curvature associated with the unique cross-section of devices hereof. Such dual functionality not only enhances the ease of implantation but also offers flexibility in patient management.

[00101] Experimental

[00102] Materials. A representative studied embodiment of support 20b hereof was fabricated from a thin wall nitinol tube (Confluent Medical, Fremont, CA) with outer diameter of 3.429mm and inner diameter of 3.175 which was used as the backbone or support 20b of the device. An ultra-thin layer 30b of ePTFE (ZEUS, Orangeburg, SC) with the thickness of (20 micron or 0.02 nun) was wrapped around support 20b to prevent current flow from electrodes 40b to the metallic frame of support 20b. Platinum/iridium foils having a thickness of 50pm (Goodfellow, Pittsburgh, PA) were used as electrodes 40b. Electrodes 40b were mounted on ultra-thin layer of ePTFE 30b. Insulated platinum/iridium wires 52b with a diameter of 50pm and insulation thickness of 9pm (Goodfellow, Pittsburgh, PA) were used to make electrical connections to electrodes 40b. All materials used in the fabrication are biocompatible, including platinum/iridium, nitinol, ePTFE, and adhesives. A laser-cut nitinol stent forms backbone or support 20b of device 10b.

[00103] Fabrication Process. The tube was patterned using precision laser cutting to create a diamond-shaped pattern, and subsequently underwent thermal treatment. The dimensions of each diamond shape may, for example, be carefully designed to enable one to embed electrodes while maintaining the device integration. Considering electrode dimensions used in this work, the diamonds measured 4.5mm in length (Li) and 0.893mm in width L2, with a consistent spacing of 0.49 mm (L3) between adjacent patterns (see FIG. 7). In the embodiment of FIG. 7, L4 is 0.182 mm and Ls is 0.06 mm. In FIG. 8B, Li is 3 mm, L2 is 0.95 mm, L3 is 0.4 mm, L4 is 0.126 mm, Ls is 0.06 mm, and Lr, is 0.108 mm. In two other embodiments: (a) Li is 3 mm, L2 is 1.217 mm, L3 is 0.4 mm, L4 is 0.13 mm, Ls is 0.06 mm, and Lr> is 0.108 mm; and (b) Li is 3 mm, L2 1.29 mm, L3 is 0.29 mm, L4 is 0.2 mm, Ls is 0.06mm, Le is 0.108 mm, and L7 is 0.06 mm.

[00104] The laser-cut stent 15b was heat-treated to form tapered support structure 20b with a crescent-shaped cross-section as illustrated in FIGS. 6A through 6D. A laser cut stent 15b having a length of 5cm were prepared. Aluminum mandrel 400, which had an outer diameter of 6mm, was pushed inside the stent. The assembly was then heat treated in 500°C for 30 minutes. After heat treatment, expanded stent or cylinder 17b was quenched in cold water. At as a result of the initial heat treatment, the diameter of cylinder 17b was increased and tapered ends were formed. Subsequently, another heat treatment was performed to form the final, desired cross-sectional shape. In the second heat treatment, hollow aluminum cylinder or pipe 420, having an outer diameter of 17.145 mm and a wall thickness of 2.3114 mm as wall thickness, and solid aluminum cylinder or tube 422, having a diameter of 9.525mm, were used (FIGS. 6B and 6C). A crescent-shaped cross section was thereby formed in every section (or along the entire length of) support 20b (FIG. 6D). After forming support 20b, ultrathin ePTFE was used to cover support 20b, forming an insulating layer over all of support 20b (FIGS. 4 A through 4C). Platinum/iridium foils were cut in the dimensions of 1mm x 3mm to form electrodes 40b. Further, wires 52b were cut in 50cm lengths. Laser spot welding (Neutec, USA) was used to connect wires 52b to electrodes 40b. In the last stage, each wire 52b was punched through the ePTFE layer 30b and passed through the inner space of support 20b. Electrodes 40b were mounted on ePTFE surface using adhesive. Various patterns and arrangements of electrodes were used for study of representative SCS leads, e.g., (x columns of y electrodes; additionally the number of electrodes per column and row of may vary over the surface of the lead or the electrodes may be oriented other than in row and columns). Integrating platinum/iridium electrodes and wires, which were joined through precise laser spot welding, assists in maintaining robust electrical connections. In a number of studies, the electrodes were mounted onto the ePTFE surface to position the support struts to tightly shield the corners of the electrodes. Such a design minimizes the risk of loosening or dislocation, ensuring the electrodes remain stable during use. Such a design also assists in ensuring that the electrodes remain securely positioned within the support during the insertion and deployment process, preventing any potential damage. To further stabilize the electrodes, adhesive was applied to attach the electrodes to the ePTFE layer, securing their position. In this way, the ePTFE (or other insulating layer) not only prevents tissue entanglement throughout the support but also applies compressive force against the force applied by guarding struts on the electrodes, ensuring the electrodes remain correctly seated for optimal functionality. In a number of embodiments, the dimensions of diamond- or other-shaped openings in a support such as support 20b’ of FIG. 4D may be designed and dimensioned to enable one to, at least partially, embed electrodes 40b’ into the openings (which are created by space between the intersecting structs). Such a configuration may assist in protecting the electrodes and in maintaining device integration during in vitro mechanical characterization and in vivo implantation. To evaluate the mechanical behavior of patterned nitinol support 20b, a series of in vitro mechanical tests were conducted, focusing on bending and crushing scenarios. Testing was performed using a mechanical force measurement system (STARRETT® FMS500, L.S. Starrett Company, Athol, MA USA) equipped with a 10 N load cell (L.S. Starrett, MA, USA) operating at a sampling rate of 100 Hz. The system recorded force (F) and displacement in real time at a constant strain rate of 10 mm/min. A bending test was used to replicate a typical loading condition encountered by device 10b during navigation through the epidural space. A three-point bending setup, adhering to ASTM standard, was employed. ASTM F2606-08 (2021) Standard Guide for Three-Point Bending of Ballon- Expandable Vascular Stents and Stent Systems, the disclosure of which is incorporated herein by reference. Support 20b was supported at two points along the longitudinal or axial length of support 20b, with the load applied at the midpoint to induce bending (FIG. 16A). Displacement and force measurements were collected to characterize the backbone’s structural response under flexural loads.

[00105] For mid-line crushing studies, the crescent-shaped cross-section of support 20b necessitated specific considerations to ensure uniform loading. In that regard, a thin panel, matching the length of support 20b, was used to apply a distributed load along the mid-line of support 20b via its longer edge (FIG. 16B). The setup allowed precise measurement of the resistance of support 20b to compressive forces along the mid-line axis.

[00106] In side-line crushing studies, stabilization was important as a result of the complex geometry of support 20b. Custom supports were constructed from nitinol wire, and support 20b was welded along its side-lines to those supports (FIG. 16C). The load was then applied uniformly along the side-lines, following conditions consistent with the other tests.

[00107] In-vitro electrical characterization of the electrodes. An electrical impedance spectroscopy technique was used to demonstrate the electrical behavior of electrodes 40b to determine the functioning quality of the connections and electrodes 40b. A CH Instruments Potentiostat (CH Instruments. Inc., Austin, TX USA) was used to perform the EIS and CV tests. In those tests, a phosphate-buffered saline (PBS) solution (GIBCO™ PBS pH 7.2(1X), available from ThermoFisher Scientific, Waltham, NLA USA) was used. Also, an AgNO.t electrode was used as reference electrode and a Pt electrode as a counter electrode. Impedance was measure between 10^-1 and 10⁵ Hz. For CV measurements, tests were conducted using a 0.05 V/s scan rate and 0.001 V as sample interval within a window of -0.7 to 0.7 V. A minimum of 5 cycles were performed for each test to reach a stable condition, and then the final cycle was analyzed.

[00108] In-vitro backbone deployment test to measure resistance. The collapsibiiity of the support 20b generates radial force while it is collapsed inside needle 100b prior to deployment. This radial force creates resistance between device 10b and the internal surface of 14Ga Touhy needle 10b. To quantify this resistance, an experimental setup was used to measure the force required to push support 20b of device 10b out of needle 100b. In a first phase of testing, only support 20b was evaluated. A 50 mm-long support 40b was inserted into 14G Touhy needle 100b. Using a plunger fitted inside needle 100b, support 20b was pushed out at a displacement rate of 10 mm/min. The pushing force was recorded continuously and plotted against the deployed length of support 20b. In a number of embodiments for use in the epidural space, the self-expanding nitinol backbone is designed to exert a radial force in the range of 0.5-2.0 N/mm. This force ensures that the backbone effectively presses the electrodes against the epidural space wall, facilitating efficient electric field transfer. To achieve stable apposition and prevent any potential device migration, the backbone is configured to expand to a diameter 10-20% larger than the epidural space, providing controlled oversizing that maintains consistent and sufficient radial force to the wall. In other implantation spaces, the backbone hereof may be designed to exert a radial force in a different range as determined by the use. The exerted radial force may, for example, be controlled via design of the parameters of the stent used in forming the backbone as described above.

[00109] The foregoing description and accompanying drawings set forth a number of representative embodiments at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the scope hereof, which is indicated by the following claims rather than by the foregoing description. All changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

WHAT IS CLAIMED IS:

1. A lead, comprising: an electrode assembly which is expandable, the electrode assembly comprising a support which is compressible and is formed from a shape memory material, the support forming an interior volume therein, a flexible membrane on an exterior surface of the support; and one or more electrode attached to an outer surface of the flexible membrane; and one or more wires passing through the interior volume of the support, wherein at least one of the one or more wires is electrically connected to a different one of each of the one or more electrodes, wherein the electrode assembly is compressible to a constrained state to fit within a sheath for percutaneous delivery to a region of interest and expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath.

2. The lead of claim 1 wherein the shape memory material is a shape memory alloy.

3. The lead of claim 2 wherein the shape memory alloy is nitinol.

4. The lead of claim I wherein the flexible membrane encompasses the circumference of the support along the length thereof.

5. The lead of any one of claims 1 through 4 wherein the flexible membrane is elastic and electrically insulating.

6. The lead of claim 5 wherein the flexible membrane is formed from a polymeric material.

7. The lead of claim 6 wherein the polymeric material is selected from the group consisting of polytetrafluorethylene and polyurethane.

8. The lead of any one of claims 1 through 4 comprising a plurality of electrodes attached to the outer surface of the flexible membrane, a plurality of wires passing through the interior volume of the support, at least one of each of the plurality of wires extending to connect to a different one of the plurality of electrodes.

9. The lead of claim 8 wherein each of the plurality of wires extend from a proximal end of the support in a configuration to pass through a body in which the lead is to be implanted and connect to electronic circuitry.

10. The lead of claim 9 wherein the electronic circuitry is positioned extracorporeally.

11. The lead of any one of claims 2 through 4 wherein the support is formed from a tube comprising interconnected struts formed from the shape memory alloy which is subjected to one or more shaping heat treatment processes to create a paddle-type lead shape in the unconstrained state of the support.

12. The lead of claim 11 wherein the support is formed to have a determined cross- sectional shape, perpendicular to the axis of the support, over at least a portion of the axial length of the support.

13. The lead of claim 12 wherein the determined cross-sectional shape is a crescent shape.

14. The lead of claim 13 wherein the tube undergoes a first shaping heat treatment process to expand the diameter thereof over at least a portion of the length thereof and a second shaping heat treatment process to create the crescent shape.

15. The lead of any one of claims 1 through 4 wherein each of the one or more electrodes is at least partially recessed within an opening formed between extending, interconnected struts of the support.

16. A system, comprising: a lead comprising an electrode assembly, the electrode assembly comprising a support which is compressible and is formed from a shape memory material, the support forming an interior volume therein, a flexible membrane on an exterior surface of the support, and one or more electrodes attached to an outer surface of the flexible membrane; and one or more wires passing through the interior volume of the support, wherein at least one of the one or more wires is electrically connected to a different one of each of the one or more electrodes, wherein the electrode assembly is compressible to a constrained state to fit within a sheath for percutaneous delivery to a region of interest and expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath when removed from the sheath and electronic circuitry in electrical connection with the one or more wires and configured to transmit electrical signals between the one or more electrodes and the electronic circuitry via the one or more wire.

17. The system of claim 16 wherein the shape memory material is a shape memory alloy.

18. The system of claim 17 wherein the shape memory alloy is nitinol.

19. The system of claim 16 wherein the flexible membrane encompasses the circumference of the support along the length thereof

20. The system of any one of claims 16 through 19 wherein the flexible membrane is elastic and electrically insulating.

21. The system of any one of claims 16 through 19 wherein the flexible membrane is formed from a polymeric material.

22. The system of claim 21 wherein the polymeric material is selected from the group consisting of polytetrafluorethylene and polyurethane.

23. The system of any one of claims 16 through 19 comprising a plurality of electrodes attached to the outer surface of the flexible membrane, a plurality of wires passing through the interior volume of the support, at least one each of the plurality of wires extending to connect to a different one of the plurality of electrodes, each of the plurality of wires being in electrical connection with the electronic circuitry.

24. The system of claim 23 wherein each of the plurality of wires extend from a proximal end of the electrode assembly in a configuration to pass through a body in which the expandable lead is to be implanted and connect to the electronic circuitry.

25. The system of claim 24 wherein the electronic circuitry is positioned extracorporeally.

26. The system of claim 24 wherein the electronic circuitry is implanted.

27. The system of any one of claims 17 through 19 wherein the support is formed from a tube comprising interconnected struts formed from the shape memory alloy which is subjected to one or more shaping heat treatment processes to create a paddle-type lead shape of unconstrained state of the support.

28. The system of claim 27 wherein the support is formed to have a determined cross- sectional shape, perpendicular to the axis of the support, over at least a portion of the axial length of the support.

29. The system of claim 28 wherein the determined cross-sectional shape perpendicular to the axis of the support over at least a portion of the length thereof is a crescent shape.

30. The system of claim 29 wherein the tube undergoes a first shaping heat treatment process to expand the diameter thereof over at least a portion of the length thereof and a second shaping heat treatment process to create the crescent shape.

31. The system of any one of claims 16 through 19 wherein each of the one or more electrodes is at least partially recessed within an opening formed between extending, interconnected struts of the support.

32. A system comprising a lead, comprising an electrode assembly which is expandable, the electrode assembly comprising a support which is compressible and is formed from a shape memory material, the support forming an interior volume therein, a flexible membrane on an exterior surface of the support; and one or more electrodes attached to an outer surface of the flexible membrane, and one or more wires passing through the interior volume of the support, wherein at least one of the one or more wired is electrically connected to a different one of each one or more electrodes, wherein the electrode assembly is compressible to a constrained state to fit within a sheath for percutaneous delivery to a region of interest and expandable to an unconstrained state wherein the electrode assembly has a maximum width that is wider than the inner diameter of the sheath w'hen removed from the sheath.

33. The system of claim 32 further comprising a hollow needle through which the sheath passes.

34. A method of implanting a lead, comprising: compressing an electrode assembly of the lead of any one of claims 1 through 4 to a constrained state within a generally cylindrical sheath, percutaneous delivering the lead within the generally cylindrical sheath to a region of interest, and removing the lead from the generally cylindrical sheath so that the lead expands to an unconstrained state.

35. The method of claim 34 wherein the sheath is passed through a hollow needle.

36. The method of claim 35 wherein the lead is implanted for a diagnostic purpose or for a therapeutic purpose.

37. The method of claim 36 wherein the lead is implanted to deliver electric signals in a therapeutic procedure.

38. The method of claim 37 wherein the therapeutic procedure is pain relief.

39. The method of claim 38 wherein the region of interest is the epidural space and the therapeutic procedure is spinal cord stimulation.