Patent ID: 12226637

DESCRIPTION

Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Generally, corresponding reference numbers will be used throughout the drawings to refer to the same or corresponding parts. Also, wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts.

The following disclosure provides many different embodiments, or examples, for implementing different features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a feature on, connected to, and/or coupled to another feature in the present disclosure that follows may include embodiments in which the features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the features, such that the features may not be in direct contact. In addition, spatially relative terms, for example, “lower,” “upper.” “horizontal,” “vertical,” “above,” “over,” “below.” “beneath,” “up,” “down,” “top,” “bottom,” etc., as well as derivatives thereof (e.g., “horizontally.” “downwardly.” “upwardly.” etc.) are used for case of the present disclosure of one features relationship to another feature. The spatially relative terms are intended to cover different orientations of the device including the features. Still further, when a number or a range of numbers is described with “about,” “approximate,” and the like, the term is intended to encompass numbers that are within a reasonable range including the number described, such as within +/−10% of the number described or other values as understood by person skilled in the art. For example, the term “about 5 nm” encompasses the dimension range from 4.5 nm to 5.5 nm.

FIGS.1-4illustrate various view of a non-limiting embodiment of a lead assembly100. In more detail,FIG.1illustrates a three-dimensional perspective view of a top side (also interchangeably referred to as a front side) of the lead assembly100.FIG.2illustrates a three-dimensional perspective view of a bottom side (also interchangeably referred to as a back side) of the lead assembly100.FIG.3illustrates a planar view of the top side of the lead assembly100.FIG.4illustrates a side view of the lead assembly100.

The lead assembly100includes a thin film substrate110(also referred to as a thin film body) supporting a plurality of electrodes120, and a related wiring assembly130. In one embodiment, the wiring assembly130is configured to be connected to an electrical stimulator (not shown) or electrical pulse generator. Based on programming instructions received from an electronic programmer (e.g., a clinician programmer or a patient programmer), the electrical stimulator or pulse generator can independently deliver electrical stimulation signals to each of the plurality of electrodes120. To that end, the wiring assembly130and the thin film substrate110include a plurality of connection traces140, where each trace140is capable of establishing an electrical connection between the electrical stimulator and a corresponding electrode120. Note that each of the electrodes120is positioned on a top side of the thin film substrate110and may be flush with the planar surface of the thin film substrate110, thus allowing for stimulation pulses to be provided to a portion of a patient's body (e.g., spinal cord) when the top side of the lead assembly100is appropriately positioned with respect to the patient's body.

For example,FIG.5illustrates a multi-lumen lead150(as an example type of lead) and a portion of the lead assembly100. As shown inFIG.5, the connection traces140insure the electrical connection to each of the electrodes120when coupled with the multi-lumen lead150. The multi-lumen lead150includes an electrically insulating material containing multiple lumens160, which are separated and isolated from one another, thereby providing an ability to separately energize multiple electrodes120simultaneously. In this embodiment, each of the connection traces140is individually connected to a respective one of a plurality of connection wires170(also referred to as supply wires). The connection wires170are then individually inserted or placed within separate lumens160, thus achieving the necessary electrical connections between the multi-lumen lead150and the connection traces140. Once the connection traces140are appropriately electrically connected to the multi-lumen lead150(e.g., via the connection wires170), the lead assembly100can be then encapsulated as desired. As such, the connection traces140and connection wires170provide an effective and efficient mechanism to achieve electrical connection with the multi-lumen lead150. It is understood that although the connection traces140are illustrated as extending in a single plane herein, these could also be staggered, stacked or designed in alternative arrangements, thereby helping to control the profile of the connection traces and potentially reduce overall size of these structures. It is understood that the multi-lumen lead150described herein is merely an example of a lead structure and is not intended to be limiting. In other embodiments, alternative types of lead structures may be used instead.

Referring back toFIGS.1-4, the thin film substrate110is a polyimide thin film substrate, but those skilled in the art will recognize that several alternative materials could also be used. As will also be appreciated by those skilled in the art, polyimide substrates are well understood and generally provide efficient mechanisms to support electrical components. Multilayer structures, such as the polyimide substrate structure, can be easily achieved through existing or known manufacturing processes, thus creating a desired substrate specifically configured to address specific needs. In some embodiments, the thin film substrate110may be formed by forming a base polyimide on a glass plate, and forming a target metal layer over the base polyimide. Patternable layers, such as photoresist layers, may be formed over the target metal layer and/over the base polyimide. A plurality of photolithography processes (e.g., including processes such as photoresist exposing, etching, developing, photoresist removal, etc.) are then performed to define the shapes and contours of various components on the polyimide (such as the attachment structures of the present disclosure discussed below in more detail), as well as the connection traces140by patterning the target metal layer.

That said, although polyimide substrates offer flexibility due to their extremely thinness (e.g., ranging from several microns to tens of microns, which is thinner than a typical human hair), they are also very fragile, thus creating various challenges in real world fabrication and/or usage. For example, one of the challenges is that polyimide does not easily bond to other materials, such as molding materials. This creates additional manufacturing challenges when trying to incorporate these substrates into other devices. Based upon these challenges, polyimide substrates have not been widely incorporated into various products, including stimulation leads/stimulation electrodes.

The present disclosure overcomes these problems discussed above by implementing anchoring mechanisms as a part of the assembly100, so that the anchoring mechanisms can provide additional adhesion between the thin film substrate110and the molding materials. In more detail, the present disclosure forms stimulation leads at least in part by encasing, over molding, or coating portions of the lead itself (e.g., such as the thin film substrate110) in a silicone material180. For example, as a part of an overmolded assembly process, the lead assembly100is placed into a mold. Silicone or another type of suitable molding material is then injected into the mold, such that the bottom planar surface of the thin film substrate110is attached to the silicone when the silicone is hardened. Advantageously, even though the thin film substrate110may lack the mechanical strength or rigidity for implantation in a patient's body, the silicone material may provide the needed mechanical strength or rigidity, thus providing a stable and well-accepted structure that can be used for implantation and electrical stimulation therapy. Alternatively, another thermoplastic or thermoset could be used to encase over mold or coat the lead. In one embodiment, the silicone180is used primarily as a topcoat, which is attached to the back side, but not the front side, of the thin film substrate110. Since the stimulation therapy is delivered by electrodes120on the front side of the thin film substrate110, the application of the silicone on the back side does not adversely affect the operation and effectiveness of the stimulation electrodes120, even though the silicone provides additional structure to the lead assembly100.

Unfortunately, as mentioned above, the thin film substrate110may not easily adhere to the silicone180, since it may not be easy for two relatively smooth surfaces (e.g., the planar surfaces of the thin film substrate110and the silicone180) to bond to each other. Even when bonding between the thin film substrate110and the silicone180is achieved initially, the thin film substrate110may peel off from the silicone180over time. Such a delamination between the thin film substrate110and the silicone180may degrade the performance of the lead assembly100, interfere with the intended operation of the lead assembly, and/or render the lead assembly100partially or wholly defective.

To overcome the delamination issue discussed above, the present disclosure implements a plurality of attachment structures, such as attachment structures200and attachment structures210, as specific adhesion structures that are integrated into the thin film substrate110. In other words, the attachment structures200and210have the same material composition (e.g., polyimide or another suitable type of material for the thin film substrate) as the thin film substrate110itself, and they are fabricated alongside the thin film substrate110using the same fabrication processes, for example via the same lithography processes that were used to define the shapes and contours of the thin film substrate110. Or stated differently, the attachment structures200and210may be viewed as an integral part of the thin film substrate110itself, but their unique shapes and locations allow them to be bent in a direction away from the rest of the thin film substrate110and into or toward the silicone180, so as to increase the adhesion between the thin film substrate110and the silicone180, as will be discussed in more detail below.

In the embodiment illustrated inFIGS.1-4, eight attachment structures200and eight attachment structures210are implemented at predetermined locations on the thin film substrate110, though only some of them are specifically labeled herein for reasons of simplicity. The attachment structures200may be referred to as “edge tabs”, since they are each located on an edge230or on an edge240of the thin film substrate110. In that regard, the thin film substrate110extends in an elongated manner in an X-direction from a first end250to a second end260, where the electrodes120are separated from one another in the X-direction. The planar view ofFIG.3is defined by the X-direction and a Y-direction that is perpendicular to the X-direction, the side view ofFIG.4is defined by the X-direction and a Z-direction that is orthogonal to the plane defined by the X-direction and the Y-direction. The three-dimensional perspective views ofFIGS.1-2illustrate all three of the directions in the X. Y, and Z axis.

As shown inFIGS.1-3, the planar surface of the thin film substrate110has straight edges230and240, which each extend in the X-direction and are spaced apart from one another in the Y-direction. The straight edges230and240are joined together by rounded edges270and280, which partially extend in both the X-direction and the Y-direction. In the illustrated embodiment, the attachment structure200are implemented on the straight edges230and240, but it is understood that they may also be implemented on the rounded edges270and280in other embodiments.

In comparison to the attachment structures200, the attachment structures210(shown inFIG.2) are each located in an internal region of the planar surface of the thin film substrate110, away from the edges230/240/270/280. Furthermore, the attachment structures210have been “lifted” down from the planar surface of the thin film substrate110toward the back side (as will be discussed in more detail below), which will leave a window285or a cutout285in the planar surface for each respective attachment structure210. As such, the attachment structures210may also be referred to as “internal tabs” or “internal cutout tabs.” For example, each of the attachment structures210may be spaced apart from the nearest edge (e.g., the straight edge230) by a respective distance290. In the illustrated embodiment, the distance290is measured in the Y-direction. Since the distance290directly determines the location of each attachment structure210on the thin film substrate110, the value of the290may be configured such that the attachment structures210are distributed relatively uniformly throughout the planar surface of the thin film substrate110. The relatively uniform distribution of the locations of the attachment structures210leads to a relatively uniform distribution of the adhesion forces between the attachment structures210and the silicone180.

To facilitate the discussion of the attachment structures200and210,FIGS.6A and6Billustrate magnified planar views of the attachment structure200and the attachment structure210(also referred to as adhesion structures), respectively. With reference toFIGS.1-4and6A-6B, the attachment structures200and210each have a “T-bar” like shape. In other words, the planar view profile or contour of the attachment structures200and210resemble the capitalized letter “T”. For example, the attachment structure200includes a body portion200A and a head portion200B. The body portion200A is connected to the edge240(or edge230) of the thin film substrate110and extends away from the edge240in the Y-direction. The head portion200B is connected to the body portion200A and extends in the X-direction. In other words, a dimension of the head portion200B in the X-direction is substantially greater than a dimension of the head portion200B in the Y-direction, and the dimension of the head portion200B in the X-direction is also substantially greater than a dimension of the body portion200A in the X-direction. Since the attachment structures200are located at the edges230and240of the thin film substrate110, they may also be referred to as “edge tabs.”

Similarly, the attachment structure210includes a body portion210A and a head portion210B. The body portion210A is connected to the planar surface of the thin film substrate110(or may be reviewed as a part of the planar surface if the thin film substrate110) and extends in the X-direction. The head portion210B is connected to the body portion210A and extends in the Y-direction. In other words, a dimension of the head portion210B in the Y-direction is substantially greater than a dimension of the head portion210B in the X-direction, and the dimension of the head portion210B in the Y-direction is also substantially greater than a dimension of the body portion210A in the Y-direction.

The attachment structures200and210are foldable or bendable prior to being encased in the silicone180, so that they can protrude at an angle away from the planar surface of the thin film substrate110before being encased in the silicone180. For example, the attachment structure200is foldable or bendable in the Y-direction and the Z-direction with respect to an imaginary axis300(illustrated inFIG.6Aas dashed lines). That is, the attachment structure200can be folded or bent along the imaginary axis300, such that it protrudes away from the planar surface of the thin film substrate110at an angle, where the angle is defined by the Z-direction and the planar surface of the thin film substrate110. In some embodiments, the angle may be substantially 90 degrees. In other words, the attachment structure200, after being bent or folded, is “coming straight out of the paper” inFIG.6A. Similarly, the attachment structure210may be folded or bent in the X-direction and the Z-direction along an imaginary axis310, such that it is “coming straight out of the paper” inFIG.6B.

The attachment structures200and210promote adhesion with the silicone180. In more detail, in some embodiments before the thin film substrate110is placed into a mold as part of the overmolded assembly process, the attachment structures200and210are folded or bent to protrude away from the planar surface of the thin film substrate110toward the bottom side (e.g., 90 degrees away from the planar surface and toward the bottom side). Thereafter, the lead assembly100(with the bent/folded attachment structures) is placed into a mold, and silicone180is injected into the mold. When silicone180is hardened, the protruded attachment structures200and210will be encased in (or surrounded by) the silicone180from the bottom side of the thin film substrate110. In this manner, the adhesion between the silicone180and the thin film substrate110comes not just from a two-dimensional contact area between the planar back surface of the thin film substrate110and the silicone180, but also from the enclosure of the raised (e.g., in the Z-direction) attachment structures200and210within the silicone180. Stated alternatively, the bending of the attachment structures200and210provides a three-dimensional physical connection between the thin film substrate110and the encasing material such as the silicone180. Each attachment structure200and210provides a separate connection point for the silicone180(or another suitable type of outer molding material), thus allowing for enhanced adhesion between the silicone180and the thin film substrate110and reducing the likelihood of delamination. It is understood, however, that the folding or bending of the attachment structures200and210is optional (and not required) to achieve better adhesion between the thin film substrate110and the silicone180. In other words, even without being folded or bent, the mere presence of the attachment structures200and210alone may be capable of promoting adhesion between the thin film substrate110and the silicone180.

The fact that the head portions200B and210B are wider (in the X-direction and Y-direction, respectively) than their respective body portions200A and210A may further prevent delamination of the silicone180from the thin film substrate110, since such a delamination would pull the attachment structures200and210away from the thin film substrate110, but the wider head portions200B and210B would resist such a pulling force (i.e., the delamination force) more effectively, thereby making the adhesion between the thin film substrate110and the silicone180stronger and their delamination even less likely to occur.

In addition, the fact that the attachment structures200and210are oriented in different directions (e.g., the head portion200B of the attachment structure200extending in the X-direction VS the head portion210B of the attachment structure210extending in the Y-direction) means that the attachment structures200and210resist being pulled in both the X-direction and the Y-direction, which further increases the amount of force required to delaminate the thin film substrate110from the silicone180. Consequently, the design of orienting the attachment structures200and210in different (e.g., perpendicular) directions enhances the adhesion between the thin film substrate110and the silicone180.

Furthermore, in embodiments when the attachment structures210(i.e., the internal “cutout tabs”) are implemented, the silicone (or thermoplastic or thermoset) will fill the “cutout” areas or windows285that are formed as a result of the attachment structures210being lifted. The presence of the silicone180filling these cutout areas or windows285creates additional holding structures, which again helps to capture the thin film substrate110or promote its adhesion with the silicone180.

Based on the above discussions, it can be seen that by utilizing specifically designed physical structures such as the attachment structures200and/or attachment structures210, the present disclosure can implement a thin film substrate110(e.g., a polyimide substrate) to achieve the desired flexibility and thinness associated with the thin film materials, and at the same time, not suffer from the delamination problems that have plagued traditional thin film leads. As such, the lead assembly100of the present disclosure can efficiently and effectively deliver stimulation therapy.

It is understood that although the attachment structures200and210are implemented with a T-shaped profile in the illustrated embodiment, such a profile is not intended to be limiting. Other configurations and/or geometries could also be used to implement the attachment structures200and/or210. For example, the attachment structures200and210may not necessarily include a head portion that is differently shaped than the body portion, or they may have differently shaped head portions (e.g., wider, narrower, or exhibit different degrees of curvature), or they may even have multiple head portions, depending on design requirements and manufacturing capabilities and considerations.

The embodiment discussed above pertains to a paddle lead implementation of the lead assembly100, where the attachment structures are bent and protrude into the silicone180to promote adhesion.FIGS.7-10illustrate another embodiment of the lead assembly100(still as a paddle lead), where the attachment structures are not bent but rather are coplanar or flush with the rest of the thin film substrate. In more detail,FIG.7illustrates a three-dimensional perspective view of a top/front side of the lead assembly100.FIG.8illustrates a planar view of the top/front side of the lead assembly100without showing a silicone adhesive.FIG.9illustrates a planar view of the top/front side of the lead assembly100with the silicone adhesive shown.FIG.10illustrates a side view of the lead assembly100. For reasons of consistency and clarity, similar components appearing inFIGS.1-10will be labeled the same.

As shown inFIGS.7-10, the lead assembly100in this embodiment also includes the thin film substrate110, the electrodes120, the wiring assembly130, the conductive traces140, as well as the attachment structures200and210. However, unlike the embodiment shown inFIGS.1-4, where the attachment structures200and210are folded to protrude into the silicone180at the bottom side, the attachment structures200and210are not folded but are rather flush or coplanar with the rest of the thin film substrate110. For example, as shown clearly inFIG.8, the attachment structures200extend laterally outward from the thin film substrate110in the Y-direction. Rather than placing the lead assembly into a mold with the attachment structures200/210bent toward the bottom side, the lead assembly100in this embodiment is attached to a pre-molded silicone paddle backing180A. Therefore, the bottom surfaces of the attachment structures200and210also come into direct physical contact with the pre-molded silicone paddle backing180A.

To further increase adhesion between the thin film substrate110and the pre-molded silicone paddle backing180A, a thin layer of silicone adhesive350is applied over the top surface of the attachment structures200after the bottom planar surface of the thin film substrate110is attached to the pre-molded silicone paddle backing180A. As such, both the top surface and the bottom surface of the attachment structures200are surrounded by silicone. In other words, the attachment structures200protrude laterally (in the Y-direction) into a silicone structure formed by the pre-molded silicone paddle backing180A and the thin layer of silicone adhesive350. The majority of the top planar surface of the thin film substrate110is still free of having silicone disposed thereon, though some small amounts of the thin layer of silicone adhesive350may leak onto the edge regions of the top planar surface of the thin film substrate110in some devices. Regardless, the encasement of the laterally-protruding attachment structures200in the silicone material still offers sufficient adhesion between the thin film substrate110and the pre-molded silicone paddle backing180A, such that delamination concerns are substantially alleviated.

Note that the attachment structures210need not be bent to be encased in the pre-molded silicone paddle backing180in this embodiment, which may simplify fabrication of the lead assembly100. It is also understood that the thin layer of silicone adhesive350may or may not have the same material composition as the pre-molded silicone paddle backing180A. For example, in some embodiments, the pre-molded silicone paddle backing180A may be configured to have more rigidity than the thin layer of silicone adhesive350, but the thin layer of silicone adhesive350may be configured to be have greater adhesive properties than the pre-molded silicone paddle backing180A. This is because the pre-molded silicone paddle backing180A needs to provide form and structure to the lead assembly, whereas the thin layer of silicone adhesive350needs to firmly attach itself to the attachment structures200(and by extension, the thin film substrate110) and to the pre-molded silicone paddle backing180A.

The two embodiments discussed above each pertains to a paddle lead implementation of the lead assembly100, one with bent attachment structures, and the other one with unbent attachment structures.FIGS.11-15illustrate another embodiment of the lead assembly100, which is a cuff lead. Specifically,FIG.11illustrates a three-dimensional perspective view of the lead assembly100, where the silicone180is illustrated transparently, and where the three dimensions are defined by the X, Y, and Z directions discussed above.FIG.12illustrates a three-dimensional perspective view of the lead assembly100, where the silicone180is illustrated non-transparently, and where the three dimensions are also defined by the X, Y, and Z directions discussed above.FIG.13illustrates a side view of the lead assembly100, where the silicone180is illustrated transparently.FIG.14illustrates a side view of the lead assembly100, where the silicone180is illustrated non-transparently.FIG.15illustrates a top view of the lead assembly100, where the silicone180is illustrated transparently. The lead assembly100shown inFIGS.1-4and7-10may hereinafter be interchangeably referred to as a paddle lead assembly, whereas the lead assembly100shown inFIGS.11-15may be interchangeably referred to as a cuff lead assembly. For reasons of consistency and clarity, similar components appearing in both the paddle lead embodiments and the cuff lead embodiment will be labeled the same.

With reference toFIGS.11-15, the cuff lead assembly100also includes the thin film substrate110on which the electrodes120are located to deliver electrical stimulation and/or provide electrical sensing. Unlike the paddle lead assembly100(whose thin film substrate110has flat planar front and back side surfaces), the thin film substrate110of the cuff lead assembly100has a curved planar front and back side surfaces. For example, as shown inFIGS.12-14, the silicone180is shaped cylindrically and defines an opening400. The front side of the planar surface of the thin film substrate110is exposed to the opening400, whereas the back side of the planar surface is covered by the silicone180. Whereas the flatness of the paddle lead assembly100makes it suitable for spinal cord stimulation, the curvature of the cuff lead assembly100allows it to be used in peripheral nerve stimulation. For example, a peripheral nerve may run through the opening400, such that the front side of the electrodes120(seeFIG.12) may stimulate the peripheral nerve that is runs through the opening400.

Similar to the paddle lead assembly discussed above, the electrodes120in the cuff lead assembly100also have co-planar surfaces with the thin film substrate110. Stated differently, the exposed surfaces of the electrodes120are flush with the planar surface of the thin film substrate at the front side. The back side of the electrodes are also covered up by the silicone180. As is the case for the paddle lead, the silicone180in the cuff lead assembly100also does not directly extend to the front side but is located only to the back side of the thin film substrate110. In other words, no silicone180comes into direct physical contact with the front side of the planar surface of the thin film substrate110. As discussed above, the absence of the silicone180at the front side planar surface of the thin film substrate110is beneficial, since it reduces the likelihood of the electrodes120being pushed away from the target nerve by the “lip” created by what would be the silicone on the front side of the thin film substrate110. Here, since the front side of the thin film substrate110has no silicone180(or other types of encasement or molding material) disposed directly thereon, the electrodes120can be positioned very close to the target nerves.

The attachment structures200of the cuff lead assembly100also helps the thin film substrate110adhere to the silicone180, for reasons similar to those discussed above with respect to the paddle lead assembly. In the embodiment shown herein, the attachment structures200of the cuff lead assembly100also have T-shaped profiles, for example having a wider head portion and a narrower body portion. The attachment structures200extend away from the thin film substrate110toward the back side, for example at a 90-degree angle with respect to the edge that connects the attachment structure200to the thin film substrate110.

One difference between the paddle lead assembly and the cuff lead assembly is that the cuff lead assembly100has one or more attachment structures not only on the edges230and240, but also on the edges270and280of the thin film substrate110. The exact number of the attachment structures located on each edge is not intended to be limiting, and other embodiments may implement a different number of attachment structures on each of the edges230,240,270, and280, and the attachment structures200may be located at different locations along the edges230,240,270, and/or280than what is shown in the illustrated embodiment herein. Regardless of the number or location of the attachment structures200, their implementation as an integral component of the cuff lead assembly100results in improved adhesion between the thin film substrate110and the silicone180, since the attachment structures200reach into, and are surrounded by, the silicone180three-dimensionally. As a result, delamination problems plaguing conventional thin film leads are less likely to occur herein.

It is also understood that although the illustrated embodiment of the cuff lead assembly does not have the attachment structures210(i.e., the internal “cutout tabs”), that is also not intended to be limiting. In other embodiments of the cuff lead assembly100, the attachment structures210may also be implemented on the thin film substrate110at an internal region on the back side, so that these attachment structures210will help create further adhesion between the thin film substrate110and the silicone180by extending into and grabbing onto the silicone180located at the back side of the thin film substrate110.

As generally suggested above, the disclosed design and manufacturing methodology allows for thin film substrates to be utilized as a basis for stimulation leads. The resulting encapsulated assembly is relatively thin and flexible, thus providing a more efficient and effective lead structure. This will generally result in better tissue responses, patient comfort and efficiencies. Example applications for the lead assembly generally discussed above include cortical stimulation and maxillofacial implants. Other options and applications could easily be contemplated, especially given the flexibility and thin profile of the lead assembly.

While the above-mentioned flexibility for the lead assembly100provides many advantages, circumstances exist where this same flexibility could provide challenges for implantation or placement. To address this potential complication, one alternative is to add a stylet lumen to the finished/encased electrode assembly which will be configured to provide a desired level of rigidity. Many variations are possible, but one design would provide a stylet lumen that would extend to a distal end of the electrode assembly, thereby providing several desirable features which will aid in the placement and implantation. As a further alternative, stiffening members could be included as part of the assembly. Naturally, such stiffening members could extend partially around the substrate, or could extend in specified locations/positions. Again, several alternatives and configurations for stiffening members could be contemplated and developed. By using stiffening members and/or stylet lumens, the physical characteristics (i.e., flexibility, configuration, pliability, etc.) can be easily modified and controlled to meet many different desired conditions and applications.

The discussion above generally outlines the connection of connection traces140to multi-lumen lead150. That said, the illustrated connection traces140could be challenging to fabricate, and alternative structures may be more efficient. Also, it may be necessary to include additional structures within the multi-lumen lead150to achieve the necessary electrical connections. FIGS.16-24present several embodiments for the connection mechanisms between the electrical wires from the multi-lumen lead150and the thin film substrate110, which allow electrical stimulation signals to be transferred to related electrodes120. These connection mechanisms may be referred to as macro-to-micro transitions, where “macro” refers to the wires from the multi-lumen lead, and “micro” refers to the components on the thin film substrate, such as the traces140, since the dimensions of the wires from the multi-lumen lead150are substantially larger than the dimensions of the components on the thin film substrate110(e.g., larger by orders of magnitude). For example, a supply wire510(discussed below in more detail) coming from the multi-lumen lead150may be at least ten times thicker than the trace140in the Z-direction, or at least two times wider than the trace140(e.g., the width of the supply wire510measured in the X-direction versus the width of the trace140measured in the Y-direction).

FIGS.16A-16Cillustrate the different steps of mechanically and electrically coupling a “macro” component and a “micro” component according to a first embodiment of the present disclosure. The illustrated connection mechanism uses a transition pad500to accommodate an electrical connection between the supply wire510and a related signal trace140. The supply wire510may be an embodiment of the connection wire170discussed above with reference toFIG.5. In some embodiments, the transition pad500contains platinum. In other embodiments, the transition pad500may include other types of conductive materials. The supply wire510includes a conductive wire extending from the multi-lumen lead (or from another type of suitable lead structure) in the X-direction. A first end of the supply wire510is configured for insertion into a respective lumen160in the multi-lumen lead150, while a second end of the supply wire510is configured for bonding or attachment with the micro-component of the lead assembly100, such as the trace140, which is a non-limiting example of the signal trace140that is implemented on the thin film substrate110discussed above. In some embodiments, the supply wire510may include a metal alloy, such as a nickel-cobalt base alloy (e.g., MP35N), an alloy with a silver core, or an alloy with a platinum core.

Note that the actual device may have a plurality of supply wires510, where each supply wire510carries electrical signals to a respective one of the electrodes120, thereby allowing electrical stimulation/sensing to be delivered/sensed by the different electrodes120independently. For reasons of simplicity, however, only one supply wire510is illustrated herein.

As discussed above, the supply wire510may be considered the “macro” component herein, since it is substantially larger than components on the thin film substrate110, such as the trace140. The signal trace140may be considered the “micro” component, since its size or dimensions are substantially smaller than the supply wire510.

In this embodiment, the transition pad500is configured as a disc-like structure having an extending post520, which extends upwards from a base530. In embodiments where the extending post and the base530are both circularly shaped, the extending post520has a smaller circumference or diameter than the base530. As part of the electrical circuit, the supply wire510is connected to a back or bottom side of the transition pad500(e.g., opposite from the extending post520). Some examples of the actual connection mechanism include soldering or resistance welding. As part of this connection mechanism, an opening540is formed as part of the thin film substrate110, which is sized to receive the extending post520but not the base530of the transition pad500. For example, the opening540may have a diameter or circumference that is substantially the same as (or just slightly larger than) the diameter or circumference of the extending post520, respectively, such that the extending post520can fit through the opening540, but the base530cannot.

A conductive pad560is also implemented on the front or top side of the planar surface of the thin film substrate110, where the trace140terminates. The conductive pad560may also be viewed as an extension of the trace140, but with a larger dimension in the X-direction. In some embodiments, the conductive pad560is a platinum pad, but the conductive pad560may include other types of conductive materials in other embodiments.

As step 1 of the assembly process illustrated inFIG.16A, the extending post520is inserted through the opening540. Since the base530of the transition pad500(i.e., the portion below the extending post520) is larger than the opening540, the base530of the transition pad500does not extend into the opening540. Rather, the upper surface of the base530may come into direct physical contact with a bottom surface of the thin film substrate110to ensure that the transition pad500is firmly attached to the thin film substrate110.

As step 2 of the assembly process illustrated inFIG.16B, the extending post520has been inserted through the opening540and now protrudes over the top side of planar surface of the thin film substrate110in the Z-direction. To provide an electrical signal path, a gold wire bond570is attached to both the extending post520and the conductive pad560.

As step 3 of the assembly process illustrated inFIG.16C, an epoxy encasement590is applied to the connection structure (e.g., including the extending post520, the conductive pad560, the gold wire bond570, and at least portions of the supply wire510) and portions of the planar surface of the thin film substrate110, so as to provide protection to the connection structure and to isolate the electrical signals involved. In some embodiments, the epoxy encasement590may include a conductive epoxy material, for example, an epoxy material that contains silver.

FIGS.17A-17Cillustrate the different steps of mechanically and electrically coupling a “macro” component and a “micro” component according to a second embodiment of the present disclosure. For reasons of consistency and clarity, similar components inFIGS.16A-16C and17A-17Cwill be labeled the same. In step 1 shown inFIG.17A, the second embodiment also makes use of the transition pad500to provide necessary electrical connections between the supply wire510and the signal trace140. Unlike the first embodiment where the opening540is formed in the thin film substrate110and away from the conductive pad560, the second embodiment forms the opening540in the conductive pad560itself. In step 2, the transition pad500has its extending post520inserted into the opening540. Again, similar to the first embodiment shown inFIGS.16A-16C, since the dimensions of the opening540are smaller than the dimensions of the base530of the transition pad500, the base530does not extend through the opening540but rather is secured to the bottom surface of the thin film substrate110by pressing against it. A crimp or compression fit can also be utilized to accommodate the connection between conductive pad560and the transition pad500, or make the connection more secure. Alternatively, soldering or conductive epoxy can be used. Alternatively, the opening540can be configured as a conductive via, which will allow traditional flow soldering techniques to be used. In step 3, the epoxy encasement590is added to surround the electrically connecting components, such as the conductive pad560and the extending post520.

FIGS.18A-18Cillustrate the different steps of mechanically and electrically coupling a “macro” component and a “micro” component according to a third embodiment of the present disclosure. For reasons of consistency and clarity, similar components inFIGS.16A-16C, FIGS.17A-17C, and18A-18C will be labeled the same. In this third embodiment, the transition pad500is revised to include a recess580(or groove) between the base530and the extending post520. For example, the recess580has a smaller circumference than both the extending post520and the base530, such that an outer rim portion of the extending post520is separated from the base530in the Z-direction. Meanwhile, a slot595is cut into the conductive pad560. The slot595may face the Y-direction and is configured to substantially match the dimensions of the recess580, both in the X-direction and in the Z-direction.

In step 1 shown inFIG.18A, the third embodiment positions the transition pad500adjacent to the slot595. In step 2 shown inFIG.18B, the transition pad500is slid into the slot595. Since the slot595is smaller (e.g., in the X-direction) than the extending post520and the base530, the conductive pad560makes direct physical contact with the bottom surface of the outer rim portion of the extending post520, and/or with the top surface of the base530. In step 3 of the third embodiment shown inFIG.18C, crimping may be performed to further clamp the transition pad500with the conductive pad560. In addition, solder and/or conductive epoxy may be applied between the transition pad500and the conductive pad560to further ensure their electrical connection. In this manner, the transition pad500and the conductive pad560may collectively form a conductive via. Lastly, an epoxy encasement590is added to surround the electrically connecting components, such as the conductive pad560and the extending post520.

It is understood that although the embodiments illustrated inFIGS.16A-16C,17A-17C, and18A-18C use a circular extending post520for the transition pad500, that is not intended to be limiting. For example,FIG.19illustrates a three-dimensional perspective view of another embodiment of the transition pad500, where a ridged structure600is implemented (instead of the circular extending post520) on top of the base530that is connected to the supply wire510. The ridged structure600may be fitted through an opening similar to the opening540discussed above and protrudes over the top planar surface of the thin film substrate110. The ridged structure600may include a plurality of ridged segments, such as ridged segments600A and600B in the illustrated embodiment. Each of the ridged segments600A-600B has a flat surface620, which face each other in the X-direction. The ridged segments600A and600B may be crimped down, for example by pressing on the flat surfaces620, to make physical contact with traces140. Alternatively, conductive epoxy may be applied over the ridged segments600A-600B and over the traces140to establish the electrical connection between the ridged structure600(and therefore the supply wire510) and the traces140.

FIGS.20A-20Eillustrate the three-dimensional perspective views of several other connection techniques that make use of alternative structures designed into the thin film substrate110, in order to facilitate the macro-to-micro transition. For example, as shown inFIG.20A, the thin film substrate110may be manufactured to include a T-leg connection650, which is also made of the same polyimide material as the thin film substrate110itself. The T-leg connection650includes the trace140and a connection pad660, which is an extension of the conductive trace140. The connection pad660extends laterally away from the trace140in the Y-direction. To achieve electrical connection between the supply wire510and the T-leg connection650, both lateral extensions of the connection pad660are wrapped around the supply wire510. For example, a first lateral extension of the connection pad660may be wrapped around the supply wire510, and then the second lateral extension of the connection pad660may be wrapped around the first lateral extension of the connection pad660, which already has the supply wire510wrapped therein. The supply wire510may be considered a part of the T-leg connection650. As such, electrical connectivity between the supply wire510and the thin film substrate110(e.g., a corresponding one of the electrodes120) may be established.

FIG.20Billustrates an L-leg connection680, which is also made of the same polyimide material as the thin film substrate110itself. The L-leg connection680includes the trace140and a connection pad690, which is an extension of the trace140and that extends laterally to one side. To achieve electrical connection between the supply wire510and the L-leg connection680, portions of the connection pad690are wrapped around the supply wire510. The supply wire510may be considered a part of the L-leg connection680. As such, electrical connectivity between the supply wire510and the thin film substrate110(e.g., a corresponding one of the electrodes120) may be established.

FIG.20Cillustrates an I-leg connection700, which is also made of the same polyimide material as the thin film substrate110itself. The I-leg connection700includes the conductive trace140. In some embodiments, the trace140may define a trough or trench, through which the supply wire510is inserted in order to achieve electrical connection between the supply wire510and the I-leg connection700. The supply wire510may be considered a part of the I-leg connection700. It is understood that in the T-leg embodiment, the L-leg embodiment, and the I-leg embodiment, welding, soldering, or conductive epoxy may also be used to facilitate the electrical connections. Additionally, crimping mechanisms could also be used.

FIGS.20D and20Eillustrate three-dimensional perspective views of two alternative crimp connection techniques to facilitate the macro-to-micro transition. As shown inFIGS.20D-20E, a portion of the I-leg connection700(which includes the trace140and the supply wire510) is inserted into a sleeve720. Different materials may be used to implement the sleeve720in different embodiments. For example, in some embodiments, the sleeve720may be made of polyimide, or another type of electrically insulating material, such as a polymer, silicon, or pellethane material. In other embodiments, the sleeve720may be made of a metal material instead. As shown inFIG.20D, the supply wire510may already be in physical contact with the trace140. In embodiments where the sleeve720is made of a metal material, the sleeve720may be crimped, so as to establish physical and electrical contact between the sleeve720, the trace140, and the supply wire510. In embodiments where the sleeve720is made of the electrically insulating material such as polyimide, the sleeve720is not crimped. Rather, a conductive epoxy material may be injected into the sleeve720to establish electrical connections between the trace140and the supply wire510(e.g., since both the trace140and the supply wire510are in physical and electrical contact with the conductive epoxy injected into the sleeve720). The sleeve720may act as a barrier to hold the conductive epoxy in place and may provide electrical isolation between the different supply wires510(associated with different electrodes). As shown inFIG.20E, the supply wire510may be spaced apart from the trace140. Again, in embodiments where the sleeve720is made of metal, the sleeve720may be double crimped (one crimp between the sleeve720and the trace140, and another crimp between the sleeve720and the supply wire510) to help establish electrical connections between the supply wire510and the trace140. In embodiments where the sleeve720is made of the electrically insulating material such as polyimide, the sleeve720is not crimped, and conductive epoxy is injected into the sleeve720to help establish electrical connections between the trace140and the supply wire510.

FIGS.21A and21Billustrate three-dimensional perspective views of alternative crimp techniques to facilitate the macro-to-micro transition. Similar to the embodiments illustrated inFIG.20E, a sleeve720is provided to house the trace140and the supply wire510therein. In addition, the embodiments illustrated inFIGS.21A and21Bmay further implement a conductive cable740within the sleeve720. In the embodiment ofFIG.21A, the conductive cable740is located on the top surface of the trace140. In the embodiment ofFIG.21B, the conductive cable740is located on the bottom surface of the trace140. The conductive cable740may provide additional electrical connections to other components. In addition, the conductive cable740provides additional rigidity, since its presence within the sleeve720gives the sleeve720another body to grab onto. The sleeve720is then double crimped, with a first crimp at the conductive trace within the sleeve720, and a second crimp at the supply wire510within the sleeve720. As such, the trace140(as a part of the thin film substrate110) is crushed between the conductive cable740and the sleeve720, thereby reinforcing the electrical connection. In the embodiment described above, the sleeve720is made of a metal material. It is understood that in alternative embodiments, the sleeve720may be made of a non-conductive material such as polyimide, in which case conductive epoxy may be injected into the sleeve720to establish the electrical connection between the trace140, the supply wire510, and the conductive cable740, with no crimping involved.

FIG.22illustrates a three-dimensional perspective view of a connection mechanism to facilitate the macro-to-micro transition according to yet another embodiment of the present disclosure. In this embodiment, the supply wire510is bonded to a conductive pad760. The conductive pad760is connected to, or implemented as an extension of, the trace140. The conductive pad760may include platinum, or at least has a platinum surface. In the embodiment illustrated inFIG.22, the supply wire510is directly bonded to the conductive pad760using a laser welding process. As the inventors of this present disclosure have recognized, due to the extreme thinness of a typical conductive pad formed on the thin film substrate110, the energy required to bond the supply wire510to the conductive pad760directly via the laser welding process would exceed what a conductive pad (that is typically implemented on a thin film substrate110) can tolerate. In other words, the energy associated with laser welding the supply wire510to a typical conductive pad would likely damage the typical conductive pad, thereby degrading its performance or rendering it unusable.

To address this issue, the present disclosure increases the thickness (e.g., in the vertical Z-direction) of the conductive pad760, before laser welding is performed to bond the supply wire510to the conductive pad760. In some embodiments, an electroplating process is performed to form the conductive pad760with an enhanced thickness on the thin film substrate110, or alternatively, thicken a typical conductive pad that is already formed on the thin film substrate110. As such, the thickness of the conductive pad760is substantially greater than a thickness of the rest of the trace140. In some embodiments, the thickness of the trace140is in a range between about 2.5 microns and about 3 microns, and the thickness of the conductive pad760(after electroplating) is in a range between about 50 microns and about 70 microns. With the increased thickness, the conductive pad760can now tolerate the energy associated with the laser welding process, thus allowing the supply wire510to be directly bonded to the conductive pad760.

FIGS.23A-23Billustrate three-dimensional perspective views of another embodiment of a connection mechanism to facilitate the macro-to-micro transition. In more detail, the I-leg connection700(as the “micro” component and discussed above with reference toFIG.20C) is inserted directly to the lumen160of the multi-lumen lead150(as the “macro” component discussed above with reference toFIG.5). The electrically insulating material of the multi-lumen lead150is illustrated non-transparently inFIG.23Aand transparently inFIG.23B. The supply wire510coming out of each of the lumens is placed on the trace140of the corresponding I-leg connection700that is inserted into the lumen. The lumen is then backfilled with a conductive epoxy material to lock the I-leg connection700in place with the supply wire510and to ensure their electrical connection is firmly established. It is understood that a plurality of the I-leg connections700may be implemented, for example, one for each of the lumens160. However, for reasons of simplicity, only one such I-leg connection700is shown herein.

FIG.24illustrates a top view of a staggered legs arrangement for the lead assembly100on a mask according to an embodiment of the present disclosure. In more detail, the mask may be a lithography mask used in a lithography process to define the shapes and sizes of the various components of the lead assembly100. Thus, the patterns of the mask shown inFIG.24are labeled the same as their corresponding components in the fabricated lead assembly100.

The embodiment ofFIG.24implements four instances of the L-leg connection680discussed above with reference toFIG.20B, which are illustrated inFIG.24as the L-leg connections680A,680B,680C, and680D. Each of the L-leg connections680A-680D includes a respective one of the traces140that are routed to the thin film substrate110. Each of the L-leg connections680A-680D also includes a respective conductive pad690A,690B,690C, and690D, that is connected to the respective trace140. As discussed above, each of the conductive pads690A-690D may receive a respective supply wire510(i.e., the “macro” component) from the multi-lumen lead150. A conductive epoxy may be applied to the supply wire510and the respective conductive pad690A/B/C/D located below in order to physically and electrically connect them together. It will be recognized that in some alternative embodiments, the conductive pads690A/B/C/D could also be connected to their respective supply wires510using techniques such as crimping, welding, or soldering.

The conductive pads690A-690D are arranged in a staggered configuration. For example, the conductive pad690A is located the closest to the thin film substrate110in the X-direction and is located “above” the rest of the conductive pads690B,690C, and690D in the Y-direction. The conductive pad690B is located farther away from the thin film substrate110in the X-direction than the conductive pad690A and is located “below” the conductive pad690A in the Y-direction, but it is located above the rest of the conductive pads690C and690D in the Y-direction. The conductive pad690C is located farther away from the thin film substrate110in the X-direction than the conductive pads690A-690B and is located “below” the conductive pads690A-690B in the Y-direction, but it is located above the conductive pad690D in the Y-direction. The conductive pad690D is located the farthest away from the thin film substrate110in the X-direction and is located “below” all the conductive pads690A-690C in the Y-direction.

Such a staggered arrangement for the conductive pads690A-690D helps defer the “bulk” attributed to the “legs” of the L-leg connections (e.g., the “legs” are the conductive pads690A-690D). Had the conductive pads690A-690D not been staggered, the spacing between their corresponding traces140would have to be significantly widened in the Y-direction, in order to ensure that the conductive pads690A-690D do not short into each other. But by staggering the conductive pads690A-690D, the bulk attributed to the conductive pads690A-690D does not rise very much above just the size (e.g., in the Y-direction) of one of the conductive pads690A-690D. Consequently, mask space and/or actual device space, which may be valuable, may be conserved by the staggered L-leg connections shown inFIG.24.

In some embodiments, an assembly fixture is used to align the staggered conductive pads690A/B/C/D, so that the supply wires510can be attached thereto using conductive epoxy.FIGS.25A-25Eillustrate top views several embodiments of such assembly fixtures800A,800B,800C, and800D. The assembly fixtures800A (shown inFIG.25A) and800C (shown inFIG.25C) each surrounds an entirety of the thin film lead assembly100in the top view, whereas the assembly fixtures800B (shown inFIG.25B) and800D (shown inFIG.25D) each surrounds a portion of the thin film lead assembly100in the top view. The assembly fixtures800A-800D reduce the complexity or difficulty in handling the traces140, for example, the “legs” of the T-leg. L-leg, or I-leg connections discussed above.

In more detail, due to the fact that the traces140are thin, narrow, and light in weight, they could curl up or down (e.g., in the Z-direction), or otherwise flop around and potentially get entangled with one another after the thin film lead assembly100is taken out of a box or a tray. This makes the handling of the thin film lead assembly100more difficult. Furthermore, the curling/flopping/entanglement of the traces140may potentially damage or the trace or degrade its electrical performance. Unfortunately, conventional thin film leads have not devised a satisfactory solution to this problem.

The present disclosure overcomes the problems discussed above by implementing the assembly fixtures800A-800D that help secure the traces140in place until the traces are ready for bonding (e.g., with the other connection mechanisms discussed above). For example, the assembly fixtures800A-800D are fabricated from the same material (e.g., polyimide) as the thin film substrate110. In other words, the assembly fixtures800A-800D and the thin film substrate110come from the same sheet of thin film substrate material, and their respective outlines or contours are defined by a laser cut process subsequently. However, such a laser cut process is specifically configured to leave “bridges”820(labeled and shown more clearly in the magnified view of a bottom portion of the thin film lead assembly100inFIG.25E) that connect the assembly fixtures800A-800D to their respective thin film substrates110. The bridges820are portions of the thin film substrate material (e.g., polyimide) that are not cut or etched and that are remain between the thin film substrate110and the assembly fixtures800A-800D after the laser cut process. Through these bridges820, the assembly fixtures800A-800D can weigh down, or hold planar, the portions of the thin film substrate110on which the conductive pads (such as the conductive pads690A-690D discussed above with reference toFIG.24) will be formed. And since these portions of the thin film substrate110are tied to respective ones of the traces140, the traces140are also weighed down or held planar via the bridges820to the assembly fixtures800A-800D. When the traces140are ready to be bonded to the connection mechanisms discussed above, the bridges820may be removed, for example, using a scalpel, a knife, a blade, or another suitable cutting mechanism. The removal of the bridges820then free up the corresponding trace140for attachment with other structures, such as the connection mechanisms discussed above. In some embodiments, the bridges820are removed one at a time, so that the associated trace140may be bonded to a suitable connection mechanism before the next bridge820is removed. In this manner, the assembly fixtures800A-800D can effectively prevent the undesirable curling, flopping, or entanglement of the traces140.

FIGS.26A-26Cillustrate perspective, top, and side views of the thin film lead assembly100, respectively, according to another embodiment of the present disclosure. This embodiment of the thin film lead assembly100is a cuff lead, similar to the cuff lead illustrated inFIGS.11-15. However, compared to the embodiment of the cuff lead inFIGS.11-15, the embodiment of the cuff lead inFIGS.26A-26Chas a substantially longer body portion100A. In that regard, the thin film lead assembly100includes the body portion100A, a macro-to-micro transition portion100B, and a therapy-delivery portion100C. The macro-to-micro transition portion100B may refer to the various embodiments of mechanisms that are discussed above in association withFIGS.16-24. In other words, the macro-to-micro transition portion100B is where the conductors from the multi-lumen lead are connected to the conductors (e.g., the traces) of the thin film lead assembly100. The therapy-delivery portion100C may refer to the portion of the thin film assembly100containing the electrodes, as well as the attachment structures discussed above in association withFIGS.1-15. Via the electrodes, the therapy-delivery portion100C may apply electrical stimulation therapy to a target issue of a patient's body, for example, to a peripheral nerve, a spinal cord, or a pelvic nerve or a pudendal nerve.

The body portion100A connects the macro-to-micro transition portion100B to the therapy-delivery portion100C, and it may include a thin film substrate and a trace implemented thereon. The substantially greater dimension (in the X-direction) of the body portion100A herein may offer certain advantages. For example, the macro-to-micro transition portion100B may be bulky. If the body portion100A is too short, the macro-to-micro transition portion100B would be implemented very close to the therapy-delivery portion100C. Such a close proximity between the macro-to-micro transition portion100B and the therapy-delivery portion100C may exert excessive pressure on the therapy-delivery portion100C, which in turn exerts undue pressure to the target nerve tissue. This may degrade the efficacy of the electrical stimulation therapy or cause patient discomfort, which is undesirable. Here, by implementing a long body portion100A, the bulk associated with the macro-to-micro transition portion100B is deferred away from the therapy-delivery portion100C. As such, even if the macro-to-micro transition portion100B is bulky, the amount of pressure it exerts to the therapy-delivery portion100C (and thus to the target nerve tissue) may be negligible. Therefore, the efficacy of the electrical stimulation therapy may be substantially improved.

In some embodiments, the length of the body portion100A shown inFIGS.26A-26Cmay be in a range between about 1 inch and about 6 inches, for example, between about 4 inches and about 6 inches in some embodiments. In comparison, the length of the corresponding body portion in the embodiment shown inFIGS.11-15may be in a range between about ¼ inch and about 1 inch. As such, it can be seen that the body portion100A herein is substantially longer (e.g., multiple times longer) than the corresponding body portion in a similar thin film lead assembly. Another metric of describing the “long” thin film lead assembly100of the embodiment ofFIGS.26A-26Cis via a ratio between the length of body portion100A and the length of the therapy-delivery portion100C. In some embodiments, the ratio between the length of body portion100A and the length of the therapy-delivery portion100C (both measured in the X-direction) is in a range between about 10:1 and about 30:1. In other words, the body portion100A may be 10 times to 30 times longer than the therapy-delivery portion100C. It is understood that these numerical ranges are not randomly chosen but rather are specifically configured to optimize performance. If the body portion100A is too short, the bulk of the macro-to-micro transition portion100B would not be sufficiently deferred away from the therapy-delivery portion100C, and the target nerve tissue may still experience too much undue pressure from the macro-to-micro transition portion100A. On the other hand, if the body portion100A is too long, it may lead to not only a waste of materials (to implement such a long lead), but also an increased difficulty in fabricating and/or handling the thin film lead assembly100. By configuring the length of the body portion100A to be within the ranges described above, the present disclosure ensures that the “bulk” can be adequately deferred in order to reduce the undue pressure on the target nerves, while still making the fabrication and handling of the thin film lead assembly100sufficiently simple. It is understood that these ranges may be customized for a specific patient. In other words, depending on the specific anatomy of the patient, different dimensions and/or ranges may be configured to optimize the therapeutic efficacy.

In some embodiments, different amounts of silicone may be applied to the body portion100A and the therapy-delivery portion100C. For example, instead of applying equal amounts of silicone (or another type of molding material that provides rigidity to the structure of the thin film lead assembly100) to both the body portion100A and the therapy-delivery portion100C, the present disclosure may apply a thinner layer of silicone to the body portion100A and a thicker layer of silicone to the therapy-delivery portion100C. The thinner layer of silicone for the body portion100A may provide more flexibility to the body portion100A and reduce the amount of pressure it may exert against the therapy-delivery portion100C, and thus also reduce the pressure load against the target nerve tissue.

It is understood that althoughFIGS.26A-26Cillustrate a cuff lead as an embodiment of the “long body” embodiment of the thin film lead assembly100, the “long body” concept may apply to other types of thin film lead assemblies as well, for example to planar paddle thin film lead assemblies.

FIG.27is a flowchart illustrating a method1000of fabricating a thin film lead assembly. The method1000includes a step1010to provide a thin film substrate having a plurality of electrodes disposed thereon. The electrodes are exposed from a front side of the thin film substrate. The thin film substrate contains polyimide or another suitable type of thin film material and includes a plurality of tabs that extend outwards.

The method1000includes a step1020to fold each of the tabs toward a back side of the thin film substrate.

The method1000includes a step1030to apply a molding material to the back side of the thin film substrate. The molding material encases each of the tabs therein, thereby promoting adhesion between the thin film substrate and the molding material.

In some embodiments, the step1010comprises fabricating the thin film substrate and the tabs simultaneously at least in part via one or more lithography processes, wherein the tabs are fabricated as integral parts of the thin film substrate.

FIG.28is a flowchart illustrating a method1100of implementing a macro-to-micro connection for a thin film lead assembly. The method1100includes a step1110to provide a thin film substrate having an electrode and a trace disposed thereon. The electrode is connected to the trace, and wherein the thin film substrate contains polyimide or another suitable type of thin film material.

The method1100includes a step1120to provide a supply wire that is substantially larger than the trace. A first end of the supply wire is configured for insertion into a lumen of a multi-lumen lead.

The method1100includes a step1130to couple a second end of the supply wire to the trace via a coupling structure.

In some embodiments, the coupling structure includes a transition pad having a base and an extending post. The step1130may further include the following steps: forming an opening in the thin film substrate; maneuvering the transition pad partially through the opening such that the extending post is disposed above the thin film substrate and the base is disposed below the thin film substrate; and attaching the extending post to the trace via wire bonding or via direct physical contact.

In some embodiments, the step1130may include the following steps: performing electroplating to increase a thickness of a conductive pad on the thin film substrate, wherein the conductive pad is connected to the trace; and laser welding the second end of the supply wire to the conductive pad after the electroplating.

In some embodiments, the coupling structure includes a T-leg connection structure or an L-leg connection structure that each have a connection pad that extends laterally outwards. The step1130may include wrapping the connection pad around the supply wire.

In some embodiments, the coupling structure includes a polyimide tube and an I-leg connection structure. The step1130may include the following steps: inserting the supply wire and the I-leg connection structure into the polyimide tube, and filling the polyimide tube with a conductive epoxy.

In some embodiments, the coupling structure further includes a conductive wire. The step1130may further include the inserting the conductive wire into the polyimide tube such that the conductive wire is located between the I-leg connection structure and the polyimide tube.

The devices and methods implemented in the manner described in the present disclosure may offer advantages over conventional devices and methods. However, it is understood that not all advantages are discussed herein, different embodiments may offer different advantages, and that no particular advantage is required for any embodiment. One advantage is that the attachment structures (e.g., the T-shaped attachment structures200and210discussed above) may enhance adhesion between the thin film substrate and a molding material such as silicone. Instead of relying on just the adhesion between a planar surface of a thin film substrate and silicone to prevent potential delamination, the attachment structures of the present disclosure offer additional connection points for the silicone material. For example, the attachment structures may extend into the silicone, and their encasement in the silicone makes it more difficult for the thin film substrate to be pulled off of the silicone, or vice versa. As a result, the likelihood of delamination between the thin film substrate and the silicone is substantially reduced. Another advantage is a feasible macro-to-micro transition. Since the sizes and dimensions of the macro component (e.g., the supply wire from the lumen) are so much larger than the traces on the thin film substrate, it is typically very difficult to establish a connection between them without damaging some of the components involved. The present disclosure overcomes this problem by implementing a plurality of feasible structures that could each be used to facilitate such a macro-to-micro transition. For example, the macro-to-micro coupling structures may include transition pads and/or bond wires, T-leg/L-leg/I-leg connections, sleeves/tubes filled with conductive epoxy, staggered arrangements of L-legs, etc. Another advantage is that the fixture discussed above helps weigh down the traces to facilitate the manipulation and handling of the thin film leads. Other advantages include low costs and case of implementation.

One aspect of the present disclosure involves an apparatus. The apparatus includes an elongate thin film body extending from a first end to a second end. The apparatus includes a plurality of electrodes disposed on the thin film body. The apparatus includes a plurality of electrode connection traces that are each coupled to a respective one of the electrodes. The apparatus includes a plurality of attachment structures placed at predetermined locations about the thin film body. The apparatus includes an outer molding surrounding the thin film body, the attachment structures providing connection points for the outer molding, thus allowing for adhesion between the outer molding and the thin film body.

Another aspect of the present disclosure involves an apparatus. The apparatus includes a substrate that contains polyimide or another suitable type of thin film material. The apparatus includes a plurality of electrodes disposed on the substrate, wherein the electrodes are configured to deliver electrical stimulation to nerve issue located on a first side of the substrate. The apparatus includes a molding material disposed on a second side of the substrate opposite the first side, wherein the disposition of the molding material on the substrate provides rigidity to the substrate. The apparatus includes a plurality of attachment structures disposed on the substrate, wherein the attachment structures each protrude into, and are surrounded by, the molding material on the second side.

Yet another aspect of the present disclosure involves a method. The method includes providing a thin film substrate having an electrode and a trace disposed thereon, wherein the electrode is connected to the trace, and wherein the thin film substrate contains polyimide or another suitable type of thin film material. The method includes providing a supply wire that is substantially larger than the trace, wherein a first end of the supply wire is configured for insertion into a lumen of a multi-lumen lead. The method includes coupling a second end of the supply wire to the trace via a coupling structure.

Yet another aspect of the present disclosure involves a lead assembly. The lead assembly includes a thin film body supporting a plurality of stimulation electrodes, wherein the thin film body includes a polyimide substrate or another suitable type of thin film substrate. The lead assembly includes a plurality of electrode connection traces situated on the thin film body and electrically connected to respective ones of the plurality of stimulation electrodes. The lead assembly includes a connection wire configured to provide stimulation signals for transmission to the plurality of stimulation electrodes, wherein the connection wire extends from a lumen of a multi-lumen lead and is substantially larger than each of the electrode connection traces. The lead assembly includes a coupling structure configured to provide electrical connection between the connection wire and the electrode connection traces.

Yet another aspect of the present disclosure involves a lead assembly. The lead assembly includes a polyimide substrate or another suitable type of thin film substrate. The lead assembly includes an electrode and a connection trace situated on the polyimide substrate, wherein the electrode is connected to the connection trace. The lead assembly includes a supply wire extending from a lumen of a multi-lumen lead, wherein the supply wire is substantially larger than the connection trace. The lead assembly includes a coupling structure configured to mechanically and electrically couple the electrode and the connection trace together.

Yet another aspect of the present disclosure involves a method. The method includes providing a thin film substrate having an electrode and a trace disposed thereon, wherein the electrode is connected to the trace, and wherein the thin film substrate contains polyimide. The method includes providing a supply wire that is substantially larger than the trace, wherein a first end of the supply wire is configured for insertion into a lumen of a multi-lumen lead. The method includes coupling a second end of the supply wire to the trace via a coupling structure.

Various embodiments of the invention have been described above for purposes of illustrating the details thereof and to enable one of ordinary skill in the art to make and use the invention. The details and features of the disclosed embodiment [s] are not intended to be limiting, as many variations and modifications will be readily apparent to those of skill in the art. Accordingly, the scope of the present disclosure is intended to be interpreted broadly and to include all variations and modifications coming within the scope and spirit of the appended claims and their legal equivalents.