HYBRID NEUROSTIMULATION LEAD COMBINING FLEXIBLE CIRCUIT ELECTRODES WITH LEAD BODY HAVING BULK CONDUCTOR

A device includes a neural interface and a lead body. The lead body includes a bulk conductor and the neural interface includes a flexible circuit. The flexible circuit includes a microfabricated substrate and an exposed electrode. An interconnect region disposed between the electrode and the bulk conductor provides electrical connection between the electrode and the bulk conductor such that electrical signals can be communicated relative to the electrode via the bulk conductor. The interconnect region can be respectively connected to the electrode and bulk conductor by wire-bonding, welding, or other suitable connection methods.

BACKGROUND

Implantable medical devices can be used for monitoring (e.g., ongoing glucose monitoring) and for stimulation (e.g., to regulate the beating of a heart). Such devices can include electrodes. The electrodes can be placed at a target location for monitoring or stimulation. In a monitoring scenario, the electrodes gather information from the target location and the electronics package processes the information. In a stimulation scenario, the electronics package generates electrical signals that are delivered to the target location via the electrodes.

SUMMARY

Various examples of the present disclosure are directed to hybrid neural leads (e.g., including (a) a micro-fabricated thin-film electrode array suitable for accommodating complex geometry, and (b) high-reliability bulk wiring within a lead body for conveying signals to or from the electrode array), systems including the same, and methods for forming the same.

In one example, a method of fabricating a neural lead assembly is provided. The method includes providing a lead body including a bulk conductor having a first end and a second end, where the first end is configured for connection with an electronic device. The method further includes providing a flexible circuit including an exposed electrode. The method further includes providing an interconnect region. The method further includes establishing an electrical connection between the interconnect region and the exposed electrode. The method further includes joining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region. As a result, the bulk conductor of the lead body is electrically connected with the exposed electrode via the interconnect region so as to establish a path for travel of signals between the exposed electrode and the first end of the bulk conductor of the lead body.

In another example, a system is provided including a lead body, a flexible circuit, and an interconnect region. The lead body includes a bulk conductor having a first end and a second end. The flexible circuit includes an exposed electrode. The interconnect region is disposed between the exposed electrode and the bulk conductor. The exposed electrode is electrically connected to the interconnect region and the bulk conductor is joined in electrical connection with the interconnect region such that the exposed electrode and bulk conductor are in electrical communication via the interconnect region.

In a further example, a system is provided including a leady body, a flexible circuit, an interconnect region, and a multiplexer. The lead body includes a bulk conductor having a first end and a second end. The flexible circuit includes an exposed electrode. The interconnect region is disposed between the exposed electrode and the bulk conductor. The exposed electrode is electrically connected to the interconnect region and the bulk conductor is joined in electrical connection with the interconnect region such that the exposed electrode and bulk conductor are in electrical communication via the interconnect region. The multiplexer is in electrical connection with the exposed electrode and in electrical connection with the bulk conductor. The multiplexer is configured to control characteristics of signals relative to the exposed electrode in response to input received via the bulk conductor.

These illustrative examples are mentioned not to limit or define the scope of this disclosure, but rather to provide examples to aid understanding thereof. Illustrative examples are discussed in the Detailed Description, which provides further description. Advantages offered by various examples may be further understood by examining this specification.

DETAILED DESCRIPTION

Various examples described herein are directed to flexible circuits including neural interfaces and combined with associated lead bodies having bulk wiring into a hybrid neural lead in the context of neurostimulation devices and/or monitoring devices. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. For example, the flexible circuits and/or lead bodies described herein can also be used for other applications in which connections are made between electronic devices and electrodes. In some examples, the flexible circuits and/or lead bodies can be used in applications that are not implanted in human tissue.

In an illustrative example, a neurostimulation system is implanted into a human body, such as to facilitate monitoring of target tissue and/or to facilitate imparting stimulation to target tissue. The neurostimulation system includes a neural interface, an electronic device, a lead body, and an interconnect part.

The neural interface in this illustrative example is microfabricated from a flexible circuit and includes exposed electrodes that can be placed at different target locations in the human body. The microfabrication of the flexible circuit allows creation of a suitable complex geometry for the electrodes of the flexible circuit to engage or otherwise interface with a nerve or other form of target tissue.

The electronic device (e.g., a neurostimulation device) in this illustrative example is connected with the microfabricated flexible circuit of the neural interface via a suitable conduit for conveying signals between the neural interface and the electronic device (e.g., so that signals from the neural interface can be recorded at the electronic device for monitoring the tissue and/or so that signals can be imparted from the electronic device through the neural interface to stimulate the tissue). The electronic device is significantly larger than the flexible circuit of the neural interface, so the conduit there between is routed through muscle or other tissue between the location at which the neural interface is anchored and a space large enough for the electronic device.

In particular, the conduit connecting the microfabricated flexible circuit of the neural interface with the electronic device in this illustrative example includes the lead body and the interconnect part. The lead body includes bulk wires or bulk conductors that are substantially larger than the electrical connections within the flexible circuit that forms the neural interface. For example, whereas features of the flexible circuit may be on the order of less than 1 micron thick, the bulk conductors may be on the order of greater than 10 microns in thickness. The greater size of the bulk conductors allows the lead body to be more robust than the flexible circuit and exhibit greater fatigue resistance suitable for withstanding forces that may be exerted by movement of the muscle or other tissue through which the lead body is routed between the electronic device and the neural interface.

The interconnect part in this illustrative example provides a transition between the microfabricated flexible circuit of the neural interface and the bulk conductors of the lead body. The interconnect part includes bond pads formed of gold, platinum, or other suitable material. The bond pads are grouped in different sets. The sets of bond pads respectively are positioned at opposite ends of the interconnect part and are connected to one another by metal traces or other electrically conductive paths. One set of the bond pads are wire bonded, welded, or otherwise joined in electrical connection with the bulk conductors of the lead body (e.g., with each bond pad connected to a respective bulk conductor). The other set of bond pads are wire bonded, welded, or otherwise joined in electrical connection with respective contacts for electrodes of the microfabricated flexible circuit of the neural interface. The connection between the sets of bond pads thus electrically connect the bulk conductors of the lead body with the electrodes of the microfabricated flexible circuit of the neural interface and permit signals to travel between the electrodes and the electronic device via the lead body and interconnect part.

The interconnect part in this illustrative example can also include a multiplexer or controller. The multiplexer is situated between the sets of bond pads and can be a circuit, computing device, or any other component that can control routing and/or other characteristics of signals passing between the bulk conductors of the lead body and the electrodes of the microfabricated flexible circuit of the neural interface. For example, in response to power and data signals received from the electronic device through the bulk conductors, the multiplexer can select which among various electrodes will be permitted to provide a monitoring signal back through the bulk conductors to the electronic device or in which sequential order; select which among various electrodes will be permitted to provide a stimulating signal to tissue or in which sequential order; set a positive polarity or negative polarity or set some other variable characteristic of a stimulating signal to be provided by a particular electrode; or implement combinations of these or other functions. Including the multiplexer can accordingly permit the neurostimulation system to function with many controllable channels (e.g., four, eight, tens, hundreds, or more) for electrodes (e.g., which may be microfabricated or otherwise relatively much smaller and easier to include in a concentrated space in comparison to bulk conductors), while at the same time only including a small number of the bulk conductors (e.g., one for power transmission and a second for data transmission). Such use of a multiplexer to allow many electrodes with corresponding few bulk conductors may avoid an arrangement in which bulk conductors are mapped one-to-one with electrodes and may avoid a corresponding result in which the lead body would occupy too much space (accommodating the corresponding large number of bulk conductors) to be viable for implantation in the body.

Reference will now be made in detail to implementations of examples as illustrated in the accompanying drawings. Like reference indicators will be used throughout the drawings and the following description to refer to the same or like items. In many instances, similar elements may be identified by the same reference numeral and differentiated by a different letter suffix in the drawings. Thus in the following text description, elements may be referenced with suffixes (e.g., for referencing individual or specific elements such as a first electrode212A or a second electrode212B) or without suffixes (e.g., for generally or collectively referencing elements such as one or more of the electrodes212).

FIG. 1illustrates a neurostimulation system100, according to at least one example. The neurostimulation system100includes an electronic device102, a neural interface104, a lead body106, and an interconnect part118connecting the lead body106and the neural interface104. The lead body106, the interconnect part118, and the neural interface104can each be respective components of a lead126. In some examples, respective components of the neurostimulation system100(e.g., the electronic device102and the lead126) are implanted in a person's body through one or more incisions.

The depicted neurostimulation system100also includes a connector assembly108, which is configured to mate the detachable lead126A with the electronic device102. The depicted connector assembly108forms an end of the lead body106and functions to provide an interface for establishing connection between the lead body106and the electronic device102. For example, the connector assembly108shown inFIG. 1can be inserted into a socket110in the electronic device102(e.g., as illustrated by arrow114) to releasably connect the connector assembly108with the electronic device102. The connector assembly108can have any suitable form factor for releasably securing the lead body106in electrical connection with the electronic device102. Examples include, but are not limited to, a planar array of contacts, a cylindrical array of contacts, or other similar contact distribution.

In some examples, a lead body106may connect to the electronic device102without the connector assembly108. For example, inFIG. 1, a fixed lead126B is depicted with a lead body106that is hard-wired or otherwise permanently connected with the electronic device102rather than releasably secured by a connector assembly108. The fixed lead126B may be utilized in addition to or in lieu of the detachable lead126A associated with the connector assembly108. The lead body106, neural interface104, and other components of the depicted fixed lead126B are substantially the same as those for the detachable lead126A associated with the connector assembly108. Accordingly, it is understood that reference herein to respective elements of a lead126may correspond to either the detachable lead126A or to the fixed lead126B.

The electronic device102can be any suitable active implantable device such as those for neuromodulation or neurostimulation. Examples of such devices include deep brain stimulators, cochlear implants, cardiac pacemakers, bioelectric devices, peripheral nerve stimulation systems, and other similar devices. In some examples, the electronic device102is a monitoring device. For example, the electronic device102can be attached to the neural interface104(e.g., via the lead body106) in order to monitor conditions of a patient's health. Examples of such devices include those used for glucose monitoring. Such devices may also include those used for glucose monitoring and delivery.

The neural interface104is formed as a flexible circuit (e.g., flex circuit, flexible printed circuit board, flex print, or other similar flexible circuit). In some examples, the neural interface104is formed using a microfabrication technique. Thus, the neural interface104can be a flexible microfabricated circuit board. The neural interface104can be formed from polyimide, paraben, liquid crystal polymer, polyether ether ketone (PEEK), plain polyester film (PEP), or any other similar material.

The neural interface104includes an array of electrodes112. Each of the electrodes112can be placed at one or many target locations within the patient's nerves, depending on the implementation. While the array of electrodes112is shown as an electrode cuff, it is understood that the electrodes112may take other form factors, including, for example, separate electrodes that can be spaced and placed separate from each other. The dimensions of the electrodes112can vary depending on the application. The neural interface104may also be in the geometry of a cuff around the nerves, such as a longitudinal intrafascicular interface or a transverse intrafascicular interface.

A coating120is shown inFIG. 1at least partially covering the lead126. The coating120can be applied using one or more of a variety of processes (e.g., dip coating, cast molding, heat shrinking, and other similar processes). The coating120may provide additional mechanical bulk for handling and/or for abrasion resistance in vivo. The coating120may be formed from flexible material such as silicone polymers (e.g., medical grade silicones) and other similarly flexible materials that also have biocompatibility. Although the coating120inFIG. 1is depicted as uniformly applied along the lead126, different portions of the lead126may differ from one another in thickness, material, or other characteristics of the coating120. InFIG. 1, respective portions of the lead body106and of the interconnect part118are partially obscured by the presence of the coating120. Accordingly, the interconnect part118and lead body106will be generally described with respect toFIG. 1, while examples of other feature that may be included or implemented in association with the interconnect part118and/or lead body106will be described below with reference to other figures in which the coating120does not obscure view.

The interconnect part118provides a transition and electrical connection between the lead body106and the neural interface104. For example, the interconnect part118can include suitable structure for connecting electrical conduits of different sizes and/or types, such as connecting microfabricated components of the neural interface104with bulk materials of the lead body106. InFIG. 1, conductive traces116from the respective electrodes112of the neural interface104are shown extending toward the interconnect part118. The interconnect part118can electrically connect the conductive traces116with the lead body106to permit travel of signals along the lead126between the electrodes112and the electronic device102. The interconnect part118can be a region of the neural interface104(e.g., a region of a flexible circuit), or the interconnect part118may be a part that is distinct form—but joined with—the neural interface104.

The depicted neurostimulation system100also includes a strain-relief feature122. In some examples, the strain-relief feature122may correspond to a tapered structure, e.g., formed by molding a tapered elastomeric material from a relatively more stiff region of one component to a relatively more flexible region of another component. In this manner, the tapered elastomeric material may provide strain relief at areas where stiff regions connect to flexible regions. Such a transition zone may prevent concentration of stresses at the transition point between the two regions that might lead to mechanical failure For example, the strain-relief feature122depicted inFIG. 1corresponds to a taper from the relatively more stiff connector assembly108to the relatively more flexible lead body106. Other methods and associated structures for strain relief may also be utilized, such as that described below with reference toFIG. 5. Moreover, structures for strain relief are not limited to placement near where a lead body106connects to an electronic device, but may additionally or alternatively be placed near where a lead body connects to an interconnect part118or at various other locations along the lead126.

FIG. 2illustrates a cutaway view of parts of a neurostimulation system200, according to at least one example. The neurostimulation system200is an example of the neurostimulation system100ofFIG. 1. In the illustrated embodiment, the neurostimulation system200includes a lead226that includes features that are similar to features of like names and reference numbers fromFIG. 1, and, as such, description of various aspects of these features are not repeated.

The lead body206shown inFIG. 2includes bulk conductors228. Specifically, a first bulk conductor228A and a second bulk conductor228B are shown inFIG. 2, although the lead body206may include any number of bulk conductors228, including one, two, or more than two. The bulk conductors228can take any suitable form factor and can be formed from any suitable bio compatible conductive material such as gold, titanium, platinum, iridium, niobium, platinum alloy, iridium alloy, nickel titanium alloy, nickel-cobalt-chromium-molybdenum alloy (e.g., MP35N®), or some other similar or otherwise suitable material. The bulk conductors228can be coated with a flexible, insulative material such as silicon, polyurethane, Teflon®, or some other similar or otherwise suitable material. The bulk conductors228can be microwires. In some examples, the bulk conductors228may be wires or other structures that are fabricated by drawing through a hole in a die or draw plate or fabricated from other processes that may differ from the microfabrication process that can be utilized to form the flexible circuit of the neural interface204. In some examples, the bulk conductors228are distinguishable on the basis of size from features of the neural interface204. For example, the bulk conductors228may be greater than ten microns in thickness in contrast to conductive traces216of the neural interface204that may be less than one micron thick. In some examples, the bulk conductors228have a size (e.g., thickness) that is at least ten times that of a comparable size of a conductive trace216or other relevant feature of the neural interface204.

The bulk conductors228can be arranged in any suitable manner along the length of the lead body206. As one example, in a first lead body portion206A shown inFIG. 2, the bulk conductors228are wrapped around a mandrel230(e.g., which may be non-conductive) and occupy space in an annulus234between the mandrel230and a casing232of the lead body206. The bulk conductors228can be electrically isolated from one another (e.g., to allow distinct signals to be carried through the different bulk conductors228), such as by the inclusion of insulative coatings on one or more of the bulk conductors228A or228B or by spacing the coils of the different bulk conductors228A and228B apart from one another by a sufficient amount along the mandrel230to prevent electrical conductive interaction between the separate bulk conductors228A and228B. As another example, in a second lead body portion206B shown inFIG. 2, the bulk conductors228are routed respectively through separate lumens238A and238B formed by internal walls236positioned within the second lead body portion206B. In some examples, the separate lumens238can have insulated boundaries that can prevent electrical contact between bulk conductors228that do not have respective insulative coatings. AlthoughFIG. 2illustrates an arrangement with both wrapping about a mandrel230and routing through lumens238in the same lead body206, these or other routing arrangements of bulk conductors228may be utilized individually or in other combinations or arrangements.

InFIG. 2, the different bulk conductors228A and228B are electrically coupled (e.g., at a first or proximal end) to respective separate contacts240A and240B in the connector assembly208. The contacts240can mate with respective features in the electronic device102to facilitate transfer of signals to or from the electronic device102via the lead body206. The contacts240may correspond to planar, cylindrical, or other shapes for releasable engagement or for permanent engagement.

The bulk conductors228inFIG. 2are also shown coupled (e.g., at a second or distal end) to an interconnect part218. The interconnect part218inFIG. 2includes a substrate that is distinct from the flexible circuit that forms the neural interface204. In particular, in the arrangement inFIG. 2, the flexible circuit that forms the neural interface204is shown overlaying a portion of the interconnect part218. The substrate of the interconnect part218can include ceramic material or other forms of non-conductive or suitable material.

The interconnect part218inFIG. 2includes a first set of bond pads242and a second set of bond pads246connected by respective electrically conductive paths244(e.g., formed by metal traces or other conductive material on the interconnect part218). The first set of bond pads242can facilitate connection of the bulk conductors228with the interconnect part218, the second set of bond pads246can facilitate connection of electrodes212of the neural interface204with the interconnect part218, and the conductive paths244between the first set of bond pads242and the second set of bond pads246can facilitate travel of signals between the respectively connected bulk conductors228and the neural interface204.

The bulk conductors228can be connected to the first set of bond pads242by any suitable method, and the neural interface204can be connected to the second set of bond pads246by any suitable method. Examples may include resistance welding, conductive epoxy, thermosonic welding, mechanical crimping, laser welding, and/or any other suitable operation. Moreover, the exposed electrodes212, the conductive traces216the first set of bond pads242, the electrically conductive path244, and the second set of bond pads246can be formed from any suitable bio-compatible conductive material such as gold, titanium, platinum, iridium, niobium, platinum alloy, iridium alloy, nickel titanium alloy, nickel-cobalt-chromium-molybdenum alloy (e.g., MP35N®), or any other suitable material. However, to aid understanding, some more specific illustrative examples will now be described.

In a first illustrative example, the interconnect part218is a ceramic substrate on which the first set of bond pads242are formed from platinum material. The bulk conductors228correspond to microwires formed of platinum or a platinum iridium blend and having a size ranging between75and125microns. Each bulk conductor228is resistance welded, laser welded, or otherwise welded to a respective bond pad in the first set of bond pads242.

In a second illustrative example, the interconnect part218is a ceramic substrate on which the first set of bond pads242are formed from platinum material.

The bulk conductors228correspond to microwires formed of gold and having a size ranging between 75 and 125 microns. Each bulk conductor228is wire-bonded (e.g., via controlled application of heat, pressure, and ultrasonic energy) to a respective bond pad in the first set of bond pads242.

In a third illustrative example, the interconnect part218is a ceramic substrate on which the second set of bond pads246are formed from gold material. The neural interface204includes conductive traces216of gold that range in size from 0.1 to 0.9 microns. Respective conductive traces216are wire bonded to a respective bond pad in the second set of bond pads246.

FIG. 3illustrates a cutaway view of parts of a neurostimulation system300, according to at least one example. The neurostimulation system300is an example of the neurostimulation system100ofFIG. 1. In the illustrated embodiment, the neurostimulation system300includes a lead326that includes features that are similar to features of like names and reference numbers fromFIG. 1and/orFIG. 2, and, as such, description of various aspects of these features are not repeated.

The lead326inFIG. 3includes a controller or a multiplexer350. The multiplexer350shown inFIG. 3is positioned on the interconnect part318. InFIG. 3, the interconnect part318includes a substrate that is distinct from the flexible circuit that forms the neural interface304.

The multiplexer350can include a circuit or circuitry to provide associated functions. In some examples, the multiplexer350can include a computing device that receives input from one or more elements of the system300and provides output to the same or other elements of the system300. For example, the computing device can include a processor and memory. The processor may be implemented as appropriate in hardware, computer-executable instructions, firmware, or combinations thereof. The memory may include any suitable form of non-transitory computer-readable medium. The memory can include instructions which are generally executed by the processor for implementing the features disclosed herein. Computer-executable instruction or firmware implementations of the processor may include computer-executable or machine-executable instructions written in any suitable programming language to perform the various functions described. The memory in various examples can store information from input provided to the computing device from other elements of the system300, which may allow the information to be later accessed and/or further processed.

The multiplexer350can control routing and/or other characteristics of signals passing between the bulk conductors328and the electrodes312of the neural interface304. To this end, the multiplexer350inFIG. 3is communicatively coupled with a first bulk conductor328A and a second bulk conductor328B (e.g., via respective bond pads342A and342B), although a different number of bulk conductors328could be used, including one, two, three, or more than three. The multiplexer350inFIG. 3is also communicatively coupled with a plurality of N electrodes312A-312N (e.g., via respective bond pads346A-346N). Although the number N of electrodes312is four inFIG. 3, any number N of electrodes312could be utilized.

The multiplexer350can utilize any of the bulk conductors328and any of the electrodes312as respective inputs and/or outputs. For example, inFIG. 3, the multiplexer350can receive power and data or control signals through the bulk conductors328. Based on the control signals received through the bulk conductors328, the multiplexer350may control how the power from the bulk conductors328is provided to the electrodes312(e.g., in a stimulating mode). Additionally or alternatively, based on the control signals received through the bulk conductors328, the multiplexer350may control how signals are provided from the electrodes312(e.g., in a monitoring mode) to the bulk conductors328. Various functions of the multiplexer350accordingly may be implemented individually or in combination.

In some examples, the multiplexer350selects which among the various electrodes412will be permitted to provide a stimulating signal to tissue. In an illustrative example, the first bulk conductor328A provides power to the multiplexer350, and the second bulk conductor328B provides a control input. Based on the control input from the second bulk conductor328B, the multiplexer350regulates at least a portion of the power input from the first bulk conductor328A toward only the first electrode412A without routing power toward the final electrode412N.

In some examples, the multiplexer350determines a sequential order in which electrodes412will be permitted to provide a stimulating signal to tissue. In an illustrative example, the first bulk conductor328A provides power to the multiplexer350, and the second bulk conductor328B provides a control input. Based on the control input from the second bulk conductor328B, the multiplexer350regulates at least a portion of the power input from the first bulk conductor328A toward the first electrode412A for a first interval, toward the final electrode412N for a second interval, and toward the first electrode412A again for a third interval, e.g., to provide a particular stimulation pattern to the target tissue.

In some examples, the multiplexer350sets a positive polarity or negative polarity or sets some other variable characteristic of a stimulating signal to be provided by a particular electrode412. In an illustrative example, the first bulk conductor328A provides power to the multiplexer350, and the second bulk conductor328B provides a control input. Based on the control input from the second bulk conductor328B, the multiplexer350regulates at least a portion of the power input from the first bulk conductor328A to affect the polarity, amplitude, frequency, or other variable characteristic of a stimulating signal communicated to a particular electrode412. The multiplexer350may adjust such a variable characteristic of a stimulating signal according to a specified pattern to provide a particular stimulation pattern to the target tissue.

In some examples, the multiplexer350selects which among the various electrodes412will be permitted to provide a monitoring signal from the tissue. In an illustrative example, the first bulk conductor328A provides a control input to the multiplexer350, and the second bulk conductor328B provides a monitoring output. Based on the control input from the first bulk conductor328A, the multiplexer350permits a monitoring signal from the first electrode312A to be conveyed along the second bulk conductor328B without allowing a monitoring signal from the final electrode412N to also be conveyed. For example, such an arrangement may correspond to the multiplexer350responding to a query from the electronic device102(FIG. 1) for a monitoring signal for a particular location (e.g., associated with the first electrode312A).

In some examples, the multiplexer350determines a sequential order in which electrodes412will be permitted to provide a monitoring signal from the tissue. In an illustrative example, the first bulk conductor328A provides a control input to the multiplexer350, and the second bulk conductor328B provides a monitoring output. Based on the control input from the first bulk conductor328A, the multiplexer350regulates signal propagation along the second bulk conductor328B to reflect a monitoring signal from the first electrode412A for a first interval, reflect a monitoring signal from the final electrode412N for a second interval, and reflect a monitoring signal from the first electrode412A again for a third interval, e.g., to provide a particular monitoring pattern from different locations of the target tissue.

The system300is not limited to the specific examples described above. For example, although some examples include power being transmitted along one bulk conductor328and data being transmitted along a separate bulk conductor328relative to the multiplexer350, in some examples, power and data may be transmitted relative to the multiplexer350along a shared or single bulk conductor328. Moreover, one bulk conductor may328be utilized to both send and receive data relative to the multiplexer350, or the multiplexer350may be coupled with a bulk conductor328to send data and a separate bulk conductor328to receive data.

FIG. 4illustrates a cutaway view of parts of a neurostimulation system400, according to at least one example. The neurostimulation system400is an example of the neurostimulation system100ofFIG. 1. In the illustrated embodiment, the neurostimulation system400includes a lead426that includes features that are similar to features of like names and reference numbers fromFIG. 1,FIG. 2, and/orFIG. 3, and, as such, description of various aspects of these features are not repeated.

The lead426inFIG. 4is similar to the lead326ofFIG. 3. However, unlike inFIG. 3, the interconnect part418inFIG. 4forms a part of (e.g., is not separate from) the flexible circuit that forms the neural interface404. Although the multiplexer450inFIG. 4is shown on an interconnect part418that forms part of the flexible circuit of the neural interface404and the multiplexer350inFIG. 3is shown on an interconnect part318that is distinct from the flexible circuit of the neural interface304, a multiplexer may additionally or alternatively be positioned on a flexible circuit that is separate from an interconnect part418.

FIG. 5illustrates a strain relief feature500, according to at least one example. The strain relief feature500can include a flex circuit portion562, a coil564, and a wire portion566. The strain relief feature500may be included, e.g., in lieu of the strain-relief feature122described above with respect toFIG. 1. The coil564may be an extension of the flex circuit portion562that has been twisted and thermo-formed to hold the shape of the coil564. The shape of the coil564may permit the strain relief feature500to be extensible and thus relieve strain that might otherwise be exerted on the flex circuit portion562and/or the wire portion566. In some examples, the respective flex circuit portion562and the wire portion566may be bonded to other portions of the lead126using methods described herein to provide electrical connections between respective elements joined by the strain relief feature.

FIG. 6is a flowchart illustrating a process600of fabricating a neural lead (e.g., leads126,226,326,426, or526), according to at least one example.

At610, the process600can include providing a lead body that includes a bulk conductor. For example, the bulk conductor may correspond to any of the bulk conductors228,328, or428as respectively described above with respect toFIGS. 2, 3, and 4. The bulk conductor may be elongate or otherwise extend between a first end and a second end of the bulk conductor, where the first end corresponds to a connector assembly108or208(e.g.,FIG. 1orFIG. 2) or is otherwise configured for connection with an electronic device such as the electronic device102(e.g.,FIG. 1).

At620, the process600can include providing a flexible circuit having a microfabricated substrate. The flexible circuit may define a neural interface (e.g., any of the neural interfaces104,204,304, or404as respectively described above with respect toFIGS. 1, 2, 3, and 4). For example, the neural interface may include an exposed electrode (e.g., any of the electrodes112,212,312, or412as respectively described above with respect toFIGS. 1, 2, 3, and 4).

At630, the process600can include providing an interconnect region. The interconnect region can include metal or other electrically conductive material arranged in an electrically conductive path between a first point (e.g., for connecting to the flexible circuit) and a second point (e.g., for connecting to the bulk conductor). In some examples, providing the interconnect region involves providing an interconnect substrate that includes the interconnect region and is distinct from the flexible circuit (e.g., as described above for the interconnect parts218and318with respect toFIGS. 2-3). In other examples, providing the interconnect region involves providing the interconnect region as a portion of the microfabricated substrate or other part of the flexible circuit (e.g., as described above for the interconnect part418with respect toFIG. 4).

At640, the process600can include establishing electrical connection between the flexible circuit and the interconnect region. This may correspond to establishing electrical connection between the interconnect region and the electrode of the neural interface. Establishing the electrical connection at640may include establishing an electrical connection between the first point of the electrically conductive path of the interconnect region and the electrode of the neural interface.

In examples in which the interconnect region corresponds to an interconnect region that is distinct from the flexible circuit (e.g., as described above for the interconnect parts218and318with respect toFIGS. 2-3), establishing electrical connection between the flexible circuit and the interconnect region may involve joining the flexible circuit in electrical connection with the interconnect region of the interconnect substrate. As an illustrative example with reference toFIG. 2, this may entail joining the flexible circuit of the neural interface204in electrical connection with the interconnect region218by joining effected via the bond pads246through wire-bonding, welding, and/or any other suitable operation described with respect toFIG. 2.

In examples in which the interconnect region corresponds to an interconnect region that is a portion of the microfabricated substrate or other part of the flexible circuit (e.g., as described above for the interconnect part418with respect toFIG. 4), establishing electrical connection between the flexible circuit and the interconnect region may involve providing the interconnect region in electrical connection with the electrode, microfabricated substrate, or other part of the flexible circuit. As an illustrative example with reference toFIG. 4, this may entail the flexible circuit of the neural interface404including the interconnect part418and respective bond pads442that are in electrical connection (e.g., via traces444) with the electrodes412.

At650, the process600can include joining the bulk conductor of the lead body in electrical connection with the interconnect region. Joining at650may include joining the second end of the bulk conductor of the lead body in electrical connection with the second point of the electrically conductive path of the interconnect region. As an illustrative example with reference toFIG. 2, this may entail joining the bulk conductor228in electrical connection with the interconnect region218by joining effected via the bond pads242through wire-bonding, welding, and/or any other suitable operation described with respect toFIG. 2.

As a result of the operations of the process at610-650, the bulk conductor of the lead body may be electrically connected with the electrode of the neural interface via the interconnect region so as to establish a path for travel of signals between the electrode and the first end of the bulk conductor of the lead body. For example, this may allow signals to travel through the first end of the bulk conductor relative to the electronic device. Examples of the electronic device can include a pulse generator or other component for receiving, transmitting, or receiving and transmitting electrical signals via the bulk conductor relative to the electrode, neural interface, or other portion of the flexible circuit.

At660, the process can include applying an insulative coating at least over a portion of the interconnect region that is joined with the bulk conductor. As an illustrative example, inFIG. 1, the leads126are shown having a coating120that obscures features of the leads126from sight.

In some aspects, a device, a system, or a method is provided according to one or more of the following examples or according to some combination of the elements thereof. In some aspects, a device or a system described in one or more of these examples can be utilized to perform a method described in one of the other examples or vice versa.

Example # 1. A method of fabricating a neural lead assembly, which may incorporate features of any of the subsequent examples, the method comprising:providing a lead body comprising a bulk conductor having a first end and a second end, the first end being configured for connection with an electronic device;providing a flexible circuit comprising an exposed electrode;providing an interconnect region;establishing an electrical connection between the interconnect region and the exposed electrode; andjoining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region;whereby the bulk conductor of the lead body is electrically connected with the exposed electrode via the interconnect region so as to establish a path for travel of signals between the exposed electrode and the first end of the bulk conductor of the lead body.

Example # 2. The method of Example # 1, or any of the preceding or subsequent examples, wherein the flexible circuit defines a neural interface and comprises a microfabricated substrate and the exposed electrode.

Example # 3. The method of Example # 1, or any of the preceding or subsequent examples, wherein the interconnect region comprises metal or other electrically conductive material arranged in an electrically conductive path between a first point and a second point;wherein the establishing an electrical connection between the interconnect region and the exposed electrode comprises establishing a first electrical connection between the first point of the electrically conductive path of the interconnect region and the exposed electrode; andwherein the joining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region comprises joining the second end of the bulk conductor of the lead body in a second electrical connection with the second point of the electrically conductive path of the interconnect region.

Example # 4. The method of Example # 3, or any of the preceding or subsequent examples, further comprisingapplying a first insulative coating over the first electrical connection that connects the first point of the electrically conductive path of the interconnect region with the exposed electrode; andapplying a second insulative coating over the second electrical connection that connects the second point of the electrically conductive path of the interconnect region with the lead body.

Example # 5. The method of Example # 1, or any of the preceding or subsequent examples, wherein the providing the interconnect region comprises providing an interconnect substrate distinct from the flexible circuit, the interconnect substrate comprising the interconnect region; andwherein the establishing an electrical connection between the interconnect region and the exposed electrode comprises joining the flexible circuit in electrical connection with the interconnect region of the interconnect substrate.

Example # 6. The method of Example # 1, or any of the preceding or subsequent examples, wherein the providing the interconnect region and the establishing the electrical connection between the interconnect region and the exposed electrode comprises providing the interconnect region as a portion of the flexible circuit and in electrical connection with the exposed electrode.

Example # 7. The method of Example # 1, or any of the preceding or subsequent examples, wherein the electronic device comprises a component for receiving, transmitting, or receiving and transmitting electrical signals via the bulk conductor.

Example # 8. The method of Example # 1, or any of the preceding or subsequent examples, wherein the component comprises a pulse generator.

Example # 9. The method of Example # 1, or any of the preceding or subsequent examples, further comprising:applying an insulative coating at least over a portion of the interconnect region that is joined with the second end of the bulk conductor.

Example # 10. The method of Example # 1, or any of the preceding or subsequent examples, wherein the bulk conductor has a thickness at least ten times that of a conductive trace of the flexible circuit.

Example # 11. The method of Example # 1, or any of the preceding or subsequent examples, wherein the bulk conductor has a thickness greater than ten microns and the flexible circuit has a conductive trace having a thickness of less than one micron.

Example # 12. The method of Example # 1, or any of the preceding or subsequent examples, wherein the joining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region is accomplished by welding the second end of the bulk conductor to a bond pad of the interconnect region.

Example # 13. The method of Example # 12, or any of the preceding or subsequent examples, wherein the welding comprises laser welding.

Example # 14. The method of Example # 12, or any of the preceding or subsequent examples, wherein the welding comprises resistance welding.

Example # 15. The method of Example # 12, or any of the preceding or subsequent examples, wherein the welding comprises ultrasonic welding.

Example # 16. The method of Example # 1, or any of the preceding or subsequent examples, wherein the joining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region is accomplished by wire-bonding the second end of the bulk conductor to a bond pad of the interconnect region.

Example # 17. The method of Example # 1, or any of the preceding or subsequent examples, wherein the establishing an electrical connection between the interconnect region and the exposed electrode is accomplished by wire-bonding the interconnect region with the flexible circuit.

Example # 18. The method of Example # 1, or any of the preceding or subsequent examples, wherein the interconnect region comprises a multiplexer;wherein the multiplexer is in electrical connection with the exposed electrode as a result of the establishing the electrical connection between the interconnect region and the exposed electrode;wherein the multiplexer is in electrical connection with the bulk conductor as a result of the joining the second end of the bulk conductor of the lead body in electrical connection with the interconnect region; andwherein the multiplexer is configured to control routing or other characteristics of signals relative to the exposed electrode in response to input received via the bulk conductor.

Example # 19. A system, which may incorporate features of any of the preceding or subsequent examples, comprising:a lead body comprising a bulk conductor having a first end and a second end;a flexible circuit comprising an exposed electrode; andan interconnect region disposed between the exposed electrode and the bulk conductor, wherein the exposed electrode is electrically connected to the interconnect region and the bulk conductor is joined in electrical connection with the interconnect region such that the exposed electrode and bulk conductor are in electrical communication via the interconnect region.

Example # 20. The system of Example # 19, or any of the preceding or subsequent examples, further comprising an electronic device coupled with the lead body for at least one of sending or receiving signals relative to the exposed electrode via the bulk conductor of the lead body.

Example # 21. The system of Example # 19, or any of the preceding or subsequent examples, wherein the lead body comprises at least one of:a plurality of lumens each containing a respective bulk conductor; ora plurality of bulk conductors coiled about a mandrel.

Example # 22. The system of Example # 19, or any of the preceding or subsequent examples, further comprising an interconnect substrate distinct from the flexible circuit, the interconnect substrate comprising the interconnect region.

Example # 23. The system of Example # 19, or any of the preceding or subsequent examples, wherein the interconnect region comprises a portion of the flexible circuit.

Example # 24. The system of Example # 19, or any of the preceding or subsequent examples, further comprising a strain-relief feature comprising a coiled portion disposed between the exposed electrode and the bulk conductor.

Example # 25. The system of Example # 19, or any of the preceding or subsequent examples, further comprising a multiplexer in electrical connection with the exposed electrode and in electrical connection with the bulk conductor, wherein the multiplexer is configured to control characteristics of signals relative to the exposed electrode in response to input received via the bulk conductor.

Example # 26. A system, which may incorporate features of any of the preceding or subsequent examples, comprising:a lead body comprising a bulk conductor having a first end and a second end;a flexible circuit comprising an exposed electrode;an interconnect region disposed between the exposed electrode and the bulk conductor, wherein the exposed electrode is electrically connected to the interconnect region and the bulk conductor is joined in electrical connection with the interconnect region such that the exposed electrode and bulk conductor are in electrical communication via the interconnect region; anda multiplexer in electrical connection with the exposed electrode and in electrical connection with the bulk conductor, wherein the multiplexer is configured to control characteristics of signals relative to the exposed electrode in response to input received via the bulk conductor.

Example # 27. The system of Example # 26, or any of the preceding or subsequent examples, wherein the bulk conductor is configured to provide power and control signals to the multiplexer.

Example # 28. The system of Example # 26, or any of the preceding or subsequent examples, wherein the bulk conductor comprises a first bulk conductor configured to provide power to the multiplexer and a second bulk conductor configured to provide control signals to the multiplexer.

Example # 29. The system of Example # 26, or any of the preceding or subsequent examples, wherein the flexible circuit comprises a plurality of electrodes; andwherein the multiplexer is configured to control routing of stimulation signals among the plurality of electrodes based on input received through the bulk conductor.

Example # 30. The system of Example # 26, or any of the preceding or subsequent examples, wherein the flexible circuit comprises a plurality of electrodes; andwherein the multiplexer is configured to control routing of monitoring signals from among the plurality of electrodes based on input received through the bulk conductor.

Example # 31. The system of Example # 26, or any of the preceding or subsequent examples, wherein the flexible circuit comprises a plurality of electrodes; andwherein the multiplexer is configured to control a sequential order of transmission of stimulation signals among the plurality of electrodes based on input received through the bulk conductor.

Example # 32. The system of Example # 26, or any of the preceding or subsequent examples, wherein the flexible circuit comprises a plurality of electrodes; andwherein the multiplexer is configured to control a sequential order of transmission of monitoring signals from among the plurality of electrodes based on input received through the bulk conductor.

Example # 33. The system of Example # 26, or any of the preceding or subsequent examples, wherein the multiplexer is configured to control a polarity or other variable characteristic of a stimulation signal to the exposed electrode based on input received through the bulk conductor.

The foregoing description of some examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. For example, more or fewer steps of the processes described herein may be performed according to the present disclosure. Moreover, other structures may perform one or more steps of the processes described herein.

Some examples in this disclosure may include a processor. A computer-readable medium, such as RAM may be coupled to the processor. The processor can execute computer-executable program instructions stored in memory, such as executing one or more computer programs. Such processors may comprise a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), field programmable gate arrays (FPGAs), and state machines. Such processors may further comprise programmable electronic devices, such as programmable logic controllers (PLCs), programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.

Such processors may comprise, or may be in communication with, media, for example, computer-readable storage media, that may store instructions that, when executed by the processor, can cause the processor to perform the steps described herein as carried out, or assisted, by a processor. Examples of computer-readable media may include, but are not limited to a memory chip, ROM, RAM, ASIC, or any other medium from which a computer processor can read or write information. The processor, and the processing described, may be in one or more structures, and may be dispersed through one or more structures. The processor may comprise code for carrying out one or more of the methods (or parts of methods) described herein.

Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and all three of A and B and C.