Assembly methods and apparatus for electrically stable connectors

Assembly methods and apparatus for electrically stable connectors are described herein where a conductive wire assembly generally comprises an insulative substrate having a length, one or more conductive elements formed along a first direction upon the substrate, an insulative coverlay formed upon the one or more conductive elements, and at least one opening or window defined through the insulative coverlay exposing a portion of the one or more conductive elements. A conductive coating is formed upon the insulative coverlay such that the conductive coating is in contact with the portion of the one or more conductive elements through the at least one opening or window and the conductive coating may have at least one region removed along a second direction in proximity to the at least one opening or window such that one or more conductive pads are formed and are electrically isolated from a remainder of the conductive coating.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for the assembly and construction of conducting elements in the form of wires or flexible cables for incorporation in space challenged applications. In particular, the present invention relates to methods and apparatus for the assembly and construction of conducting elements for electrical attachment such as connecting to sensors along the body of the guidewire.

BACKGROUND OF THE INVENTION

Guidewires may have a number of sensors or sensor assemblies integrated directly into the guidewire. Such sensor-equipped guidewires may be adapted for measuring various parameters within a patient's body. Sensors typically have one or more cables passed through the guidewire for electrically coupling the sensor element to an electronic assembly that is placed outside the patient body.

Guidewires are generally comprised of a hypotube or a solid core segment and coiled segment about a core wire which may extend through the length or a partial length of the guidewire. The core wire may be fabricated from stainless steel or Nitinol with the coiled segment fabricated from a wire or braid which provide for flexibility, pushability, and kink resistance to the guidewire. Nitinol wire, used by itself or braided with stainless steel, may further help to increase flexibility and allow the wire to spring back into shape.

Moreover, guidewires have a standard diameter of 0.014 inch (about 0.3 mm) and accommodating certain types of sensors or having multiple sensors may be limited by the relatively small space provided by the guidewire. Moreover, guidewires are typically used for insertion into and advancement through the vasculature which can present an extremely tortuous pathway. Therefore, the guidewire has to be optimized for having the best mechanical performance needing a construction closer to the conventional guidewires with core wire. This further put limitation on space. In addition, if conventional conducting elements are used, the stress generated due to flexing may cause shifts in the relative position of conductors giving rise to change in electrical coupling. Additionally, having a guidewire passing through different environments (such as a blood-filled environment within the vessels and the environment external to the patient's body) may cause electrical instability within any conducting wires which pass through the length of the guidewire. Such challenges may cause undesired artifacts in measurements thus affecting sensor performance.

Guidewires incorporating one or more electrodes along their length may present additional challenges to guidewire construction and use. For instance, the presence of a plurality of electrodes along the guidewire may require additional conductive wiring passed through the length of the guidewire. Because of the limited space and flexibility required from guidewires, any sensors and/or electrodes positioned along their length are desirably correspondingly constructed.

Consequently, there is a need to design conducting elements that take up minimal space, can be long or short depending on the need, have limited changes in electrical network during operation and offer most manufacturing and process flexibility to accommodate connections to a multitude of sensing elements.

SUMMARY OF THE INVENTION

Guidewires which are configured to sense or detect parameters within a patient body may be fabricated through a combination of various methods (e.g., chemical milling, lamination of coverlays, laser cutting, etc.) which can accommodate the micron-level electrical assemblies while still maintaining electrical stability throughout the length of the guidewire or instrument. The conductive wires which extend through the guidewire may be fabricated in a manner which enables the electrical coupling to micron-scale connections and which also provides electrical stability to the signals passing through the conductive wires.

Generally, one method of forming such a conductive wire may comprise forming one or more conductive elements along a first direction upon an insulative substrate, forming an insulative coverlay upon the one or more conductive elements, selectively forming at least one opening or window through the insulative coverlay to expose a portion of the one or more conductive elements, forming a conductive coating upon the insulative coverlay such that the conductive coating is in contact with the portion of the one or more conductive elements through the at least one opening or window, and removing at least one region of the conductive coating along a second direction in proximity to the at least one opening or window such that one or more conductive pads are formed and are electrically isolated from a remainder of the conductive coating.

Such a conductive wire assembly may generally comprise an insulative substrate having a length, one or more conductive elements formed along a first direction upon the substrate, an insulative coverlay formed upon the one or more conductive elements, at least one opening or window defined through the insulative coverlay exposing a portion of the one or more conductive elements, a conductive coating formed upon the insulative coverlay such that the conductive coating is in contact with the portion of the one or more conductive elements through the at least one opening or window, and wherein the conductive coating has at least one region removed along a second direction in proximity to the at least one opening or window such that one or more conductive pads are formed and are electrically isolated from a remainder of the conductive coating.

One variation may include a multi-strand flat wire with conductive wires (e.g., copper or other conductive material) having a diameter of, e.g., 0.0014 inch, which are individually insulated by corresponding layers of insulation (e.g., polyimide). These individual insulated wires may be bonded together, e.g., via polyimide, butryl, or other adhesive) such that the wires are aligned as a flat wire. The distal portion and proximal portion of the flat wire may have portions of the insulative layer ablated (e.g., etching, laser ablation, etc.) to form windows or openings along the distal portion and windows or openings along the proximal portion to expose the underlying conductive wires. These windows or openings may be formed so that they are staggered relative to one another along the length of the flat wire to provide sufficient spacing between the windows or openings for connection to sensors or other components.

Because the flat wire may be routed along the length of the guidewire or instrument, the flat wire is desirably electrically stable as signals pass through the length of the wire. As the guidewire or instrument may extend in use from sensors positioned within an aqueous environment (such as within a blood-filled environment within the patient body) to an environment external to the patient body such as a surgical suite or operating room, the transmission of signals through the wire may be electrically stabilized by coating the length of the wire by a conductive material such as metal (e.g., copper, palladium, gold, aluminum, etc.) which may be applied, e.g., via vapor deposition or electro-less coating methods. Application of such a conductive material makes the conducting elements housed within a constant network which is agnostic to the outside environment. For example, having a conductive saline medium versus a de-ionized water or air medium will not affect the electrical network between the distal and proximal ends of the conducting element.

This metal coating may fill in the individual windows or openings along both the distal and proximal portions. However, to prevent shorting of any electrical signals, the portions just proximal and distal to each of the windows or openings may be etched in a transverse direction relative to the length of the wire to form non-conductive barriers between adjacent windows or openings. These regions form electrically isolated pads which are electrically coupled to the respective conductive wires exposed through their respective windows or openings along both the distal and proximal portions. Because these isolated pads are also enlarged relative to the window or opening, electrically coupling sensors or other devices to individual conductive wires is greatly facilitated along both distal and proximal portions.

The flat wire assembly may be used to form flex circuit assemblies by taking an inverted flat wire and electrically coupling the exposed windows or openings to another flat wire having corresponding exposed windows or openings.

In another variation, rather than using individually insulated conducting wires, conductive traces (e.g., gold, nickel, copper, etc.) having a thickness of, e.g., 0.0005 inch to 0.002 inch, and a width of, e.g., 0.001 inch, may be electro-deposited upon an insulative substrate such as a polyimide film (e.g., Kapton®, E. I. du Pont de Nemours) having a thickness of, e.g., 0.0005 inch to 0.002 inch. The traces may be aligned to have a gap between adjacent traces of, e.g., 0.001 inch or more, and a second insulative layer coverlay such as another polyimide film (e.g., Kapton®) may be overlaid upon the traces such that the traces are sandwiched between the substrate and coverlay. These traces may be deposited upon the substrate either through an additive process or subtractive process (e.g., etching, milling, etc.) where the substrate may be initially surface-treated and cured prior to having the traces deposited upon the substrate using a suitable photo-imaging mask to the desired height and width. Once the coverlay has been deposited over the traces, the appropriate window or opening, as described herein, may be etched or ablated over the desired portion of each trace to create the staggered openings along the length of the flat wire.

Additionally, a metal coating may be further deposited upon the length of the resulting flex wire and the appropriate window or opening may be formed to create a larger surface area for electrically connecting to other elements. The coating may be deposited via a process such as vapor deposition.

Rather than having each of the traces aligned along a first or upper surface of the substrate, the traces may also be positioned along a second or lower surface of the substrate as well. While the upper surface has coverlay, the lower surface may also have a coverlay deposited upon the traces although either one or both coverlay may be optionally omitted. The traces may be positioned to be aligned directly in apposition to one another while another variation may have the traces aligned in an alternating pattern relative to one another while on respective upper and lower surfaces. In yet another variation, the traces may be aligned at a first distance from one another while the traces may be aligned at a second distance from one another where the traces on the lower surface are closer relative to the traces on the upper surface.

Because the traces may be formed into a wire extending over a distance, e.g., 72 inches or more, the traces may be formed (e.g., photo-etched) upon the substrate in a circular spiral pattern with connection pads formed on either end of the traces for distal and proximal connections. The traces may be arranged in the circular spiral pattern to allow for the packing of a long flex cable in a relatively small footprint.

A laser such as a femto-second laser may be used for singulation or an instrument such as a slitter tool (blade or roller type) may be used. An optical system may be used to track the traces and correct the slitter (or laser) path through a feedback control system. In another variation, one of the conducting traces can be used a sacrificial trace used for cutting. This may be done by injecting calculated amount of electric current that causes the conducting element to heat up beyond the glass transition temperature of the base and coverlay polymer. A slight amount of lateral pressure can be used simultaneously to form the cut. One advantage of this method would be that the trace is self-aligning potentially obviating the need for a closed loop feedback vision system. It is also noted that the holding down of the part in a precise location is desirable as a slight misalignment can lead to the cutting elements (slitter or laser) to travel into one of the traces and destroy the part. The parts may be made with fiducials that help the cutting tools to make initial alignment. Additionally, when the cutting progresses the part may have a tendency to lift off or warp locally. One method to prevent this is by using a porous vacuum chuck and another method is to mount the part on a gel pack (or similar adhesive backed surface) that keeps the part from lifting off locally. Yet another method that can be used in a laser cutting operation is to sandwich the part between two sheets of glass.

Depending up the application in which the wire is used, the length of the flex needed can vary between, e.g., 78 inches to 118 inches, depending on the length of the guidewire. There can be tooling or process limitations of getting a flex of that length. In such cases a hybrid approach may be useful where short flexes are used on both ends and these are connected to conductors. The flex pads offer the flexibility and versatility of size and configuration of pads and circuitry appropriate to the application (e.g., to attach to a corresponding pads of a MEMS sensor). The conductor wires allow the use of mass manufacturing processes.

In another variation, the conductive traces may be formed as a waveguide having active traces and ground traces arranged in various configurations. In yet another variation, the assembly may be formed for connection to multiple sensors. In another variation, each of the active traces may be aligned along the upper surface and the sensor traces may be aligned along the lower surface such that the active and sensor traces are arranged in an alternating pattern.

With the electrical traces or flat wire formed, the assembly may then be integrated within a guidewire assembly. In one method, the flat wire or flex wire assembly may be attached to a core wire such that the distal pad assembly is aligned near or at distal end of the core wire, e.g., along the reduced distal section of the core wire such that the exposed pads face away from the surface of the distal section. The traces or wires extending from the distal pad assembly may be wound or wrapped around the core. Conductive ring elements may be positioned over the distal section of the core wire and over the distal pad assembly such that each ring element corresponds to each conductive pads along the distal pad assembly. The ring elements may be soldered or otherwise attached via a conductive adhesive (such as conductive epoxy) such that each ring element is in electrical communication with each respective conductive pad. The ring elements may be made of any metal or conductive material and may serve as an electrode terminal exposed along the guidewire surface. With the ring elements desirably positioned and attached along the distal section, an electrically insulative polymer may be reflowed or molded in-between the ring elements and the resulting electrode assembly may be sized (e.g., via center-less grinding, laser ablation, etc.) to yield a seamless transition between the ring surface and polymer to produce an electrode assembly upon the guidewire.

In another variation, rather than utilizing an electrically insulative polymer, pre-cut and pre-sized polymeric spacers may be positioned upon the distal section in-between each of the ring elements to electrically isolate the resulting electrodes.

In yet another variation, rather than forming the electrode assembly directly upon the core wire, an electrode subassembly may be assembled separately and then attached to the core wire. In this variation, the base tube may also include the polymeric spacers positioned and secured between the adjacent ring elements. Alternatively, the electrode subassembly, may be similarly formed but without the polymeric spacers.

In either case, the electrode subassembly may be positioned collinearly at the distal end of the distal section of the core wire such that the distal end of the core wire is in direct apposition with the proximal end of the electrode subassembly. A collar (e.g., stainless steel, nitinol, etc.) may be positioned to surround the distal section of core wire and the proximal section of the subassembly such that the interface between distal section and proximal end is contained within the collar. The traces or wires extending from the subassembly may be passed through the interior of collar and secured around the core wire. This interface, as well as the portions of the distal section and subassembly may be secured within the collar through any number of mechanisms, e.g., solder, adhesive, crimping, etc., such that the core wire and subassembly are joined to one another in a secure manner.

With the subassembly joined to the core wire, the portions between the adjacent ring members may be filled with a reflowed or molded polymer to electrically isolate the adjacent electrodes from one another. In the event that subassembly having the polymeric spacers is used, the attachment between the core wire and subassembly may be made without having to reflow any polymer. Using either subassembly, the subassembly (and core wire) may be sized (e.g., grinding, laser ablation, etc.) to ensure that the transition between the two assemblies is flush and seamless.

DETAILED DESCRIPTION OF THE INVENTION

In assembling guidewires which are configured to sense or detect parameters within a patient body, the guidewire assemblies may be fabricated through a combination of various methods (e.g., chemical milling, lamination of coverlays, laser cutting, etc.) which can accommodate the micron-level assemblies while still maintaining electrical stability throughout the length of the guidewire or instrument. Examples of guidewire instruments which may utilize such assemblies may include a combination intravascular fractional flow resistance (FFR) and cross-sectional area (CSA) measurement instrument utilizing via multi-frequency electrical excitation via a guidewire as shown and described in further detail in U.S. Pat. Nos. 8,798,712; 8,374,689; 8,494,794; 8,825,151; U.S. Pat. Pubs. 2013/0123694; 2014/0142398; and U.S. patent application Ser. Nos. 14/535,165; and 14/535,204. Each of these references is incorporated herein by reference in its entirety and for any purpose.

One variation is illustrated in the cross-sectional end and top views ofFIGS. 1A and 1Bwhich show an exemplary multi-strand flat wire10having conductive wires12A,12B,12C,12D (e.g., copper or other conductive material) having a diameter of, e.g., 0.0014 inch, which may be individually insulated by corresponding layers of insulation14A,14B,14C,14D (e.g., polyimide). These individual insulated wires may be bonded together, e.g., via polyimide, butryl, or other adhesive) such that the wires are aligned as a flat wire as shown. As shown in the top view ofFIG. 2A, the distal portion16and proximal portion18of the flat wire10may have portions of the insulative layer ablated (e.g., etching, laser ablation, etc.) to form windows or openings20A,20B,20C,20D along the distal portion16and windows or openings22A,22B,22C,22D along the proximal portion18to expose the underlying conductive wires. These windows or openings may be formed so that they are staggered relative to one another along the length of the flat wire10to provide sufficient spacing between the windows or openings for connection to sensors or other components.

Because the flat wire10may be routed along the length of the guidewire or instrument, the flat wire10is desirably electrically stable as signals pass through the length of the wire10. As the guidewire or instrument may extend in use from sensors positioned within an aqueous environment (such as within a blood-filled environment within the patient body) to an environment external to the patient body such as a surgical suite or operating room, the transmission of signals through the wire10may be electrically stabilized by coating the length of the wire10by a conductive material such as metal (e.g., copper, palladium, gold, aluminum, etc.) which may be applied, e.g., via vapor deposition or electro-less coating methods. Application of such a conductive material makes the conducting elements housed within a constant network which is agnostic to the outside environment. For example, having a conductive saline medium versus a de-ionized water or air medium will not affect the electrical network between the distal and proximal ends of the conducting element.

FIG. 2Bshows a top view of the wire10coated along its length from the distal portion16to the proximal portion18by a metal coating24. This metal coating24may also fill in the individual windows or openings along both the distal and proximal portions16,18. However, to prevent shorting of any electrical signals, the portions just proximal and distal to each of the windows or openings may be etched in a second direction (e.g., transverse) relative to the length of the wire10to form non-conductive barriers26between adjacent windows or openings. These regions form electrically isolated pads which are electrically coupled to the respective conductive wires12A,12B,12C,12D exposed through their respective windows or openings along both the distal and proximal portions16,18. Because these isolated pads are also enlarged relative to the window or opening, electrically coupling sensors or other devices to individual conductive wires is greatly facilitated along both distal and proximal portions16,18.

The flat wire10assembly may be used to form flex circuit assemblies by taking an inverted flat wire10and electrically coupling the exposed windows or openings to another flat wire30having corresponding exposed windows or openings. An example is shown in the top and side views ofFIGS. 3A and 3Bwhich show an inverted flat wire10having staggered windows or openings32,36,40,44aligned with correspondingly staggered windows or openings34,38,42,46along flat wire30. Solder48,50,52,54may be flowed between the corresponding windows or openings to create an electrical connection between individual conductive wires. Alternatively, a material such as conductive epoxy may be dispensed upon the ablated portions of the wires and then cured using heat. Precuring adhesive on the wires may create a pad-like surface to help accommodate any alignment errors and to alleviate any assembly challenges. Furthermore, curing the adhesive may effect positive electrical contact.

In another variation, rather than using individually insulated conducting wires, conductive traces34(e.g., gold, nickel, copper, etc.) having a thickness of, e.g., 0.0005 inch to 0.002 inch, and a width of, e.g., 0.001 inch, may be electro-deposited upon an insulative substrate32such as a polyimide film (e.g., Kapton®, E. I. du Pont de Nemours) having a thickness of, e.g., 0.0005 inch to 0.002 inch, as shown in the cross-sectional end view ofFIG. 4which illustrates four traces34aligned adjacent to one another to form a flex wire assembly. The traces34may be aligned to have a gap between adjacent traces of, e.g., 0.001 inch or more, and a second insulative layer coverlay36such as another polyimide film (e.g., Kapton®) may be overlaid upon the traces34such that the traces34are sandwiched between the substrate32and coverlay36. These traces34may be deposited upon the substrate32either through an additive process or subtractive process (e.g., etching, milling, etc.) where the substrate32may be initially surface-treated and cured prior to having the traces34deposited upon the substrate32using a suitable photo-imaging mask to the desired height and width. Once the coverlay36has been deposited over the traces34, the appropriate window or opening, as previously described, may be etched or ablated over the desired portion of each trace34to create the staggered openings along the length of the flat wire (as shown above inFIG. 2A).

Additionally, a metal coating24may be further deposited upon the length of the resulting flex wire and the appropriate window or opening may be formed (as shown above inFIG. 2B) to create a larger surface area for electrically connecting to other elements. The coating24may be deposited via a process such as vapor deposition.

Rather than having each of the traces34aligned along a first or upper surface of the substrate32, as shown inFIG. 4, the traces34may also be positioned along a second or lower surface of the substrate32as well.FIG. 5Ashows a cross-sectional end view where two traces34are aligned upon the upper surface of substrate32while two additional traces38are aligned upon the lower surface of substrate32. While the upper surface has coverlay36, the lower surface may also have a coverlay40deposited upon the traces38although either one or both coverlay36,40may be optionally omitted. In this variation, the traces34and38are positioned to be aligned directly in apposition to one another while another variation, as shown inFIG. 5B, may have the traces34and38aligned in an alternating pattern relative to one another while on respective upper and lower surfaces. In yet another variation as shown inFIG. 5C, the traces34may be aligned at a first distance from one another while the traces38may be aligned at a second distance from one another where the traces38on the lower surface are closer relative to the traces34on the upper surface.

In yet another variation,FIG. 6Ashows a cross-sectional end view of a substrate32having additional traces34along the upper surface (e.g., total of four traces34) and additional traces38along the lower surface (e.g., total of four traces38) where the traces34and38are aligned in an alternating and staggered pattern.FIG. 6Bshows a cross-sectional end view where each of the traces34and38are aligned in apposition to one another along respective upper and lower surfaces. While a total of eight traces are shown, the number of traces along the upper surface and/or lower surface may be varied in any number of combinations and positions to accommodate the desired electrical configuration and application.

Because the traces may be formed into a wire extending over a distance, e.g., 72 inches or more, the traces may be formed (e.g., photo-etched) upon the substrate50in a circular spiral pattern60with connection pads formed on either end of the traces for distal and proximal connections. The traces may be arranged in the circular spiral pattern60to allow for the packing of a long flex cable in a relatively small footprint.FIG. 7Ashows an example where individual traces52,54,56,58may are formed upon the substrate50and extend to corresponding pads1d,2d,3d,4dstaggered longitudinally relative to one another.FIG. 7Bshows an example of how the individual traces64may be aligned in parallel while arranged in a circular pattern upon the substrate62. These individual traces may be singulated to form a viable flex cable or wire, i.e., the individual traces may be singled out to form into a flex circuit element, as described above.

FIGS. 8A and 8Bshow top views of a flex circuit trace print removed from the substrate where the traces are arranged in the circular spiral pattern60. A laser such as a femto-second laser may be used for singulation or an instrument such as a slitter tool (blade or roller type) may be used. An optical system may be used to track the traces and correct the slitter (or laser) path through a feedback control system. In another variation, one of the conducting traces can be used a sacrificial trace used for cutting. This may be done by injecting calculated amount of electric current that causes the conducting element to heat up beyond the glass transition temperature of the base and coverlay polymer. A slight amount of lateral pressure can be used simultaneously to form the cut. One advantage of this method would be that the trace is self-aligning potentially obviating the need for a closed loop feedback vision system. It is also noted that the holding down of the part in a precise location is desirable as a slight misalignment can lead to the cutting elements (slitter or laser) to travel into one of the traces and destroy the part. The parts may be made with fiducials that help the cutting tools to make initial alignment. Additionally, when the cutting progresses the part may have a tendency to lift off or warp locally. One method to prevent this is by using a porous vacuum chuck and another method is to mount the part on a gel pack (or similar adhesive backed surface) that keeps the part from lifting off locally. Yet another method that can be used in a laser cutting operation is to sandwich the part between two sheets of glass.

The terminal distal end and proximal end of the traces are shown extending in their respective pads1d,2d,3d,4dand1p,2p,3p,4p. An additional pad5pat the proximal end is shown as a floating pad. In applications where multiple conductors are desired but have to be packed in a tight space, dual clad traces may be laid out, as described above. This may be particularly advantageous when the sensors can be longitudinally displaced.

Depending up the application in which the wire is used, the length of the flex needed can vary between, e.g., 78 inches to 118 inches, depending on the length of the guidewire. There can be tooling or process limitations of getting a flex of that length. In such cases a hybrid approach may be useful where short flexes are used on both ends and these are connected to conductors. The flex pads offer the flexibility and versatility of size and configuration of pads and circuitry appropriate to the application (e.g., to attach to a corresponding pads of a MEMS sensor). The conductor wires allow the use of mass manufacturing processes.

As shown in the top and detail views ofFIGS. 9A and 9B, an example is shown of the distal pads1d,2d,3d,4dmay be aligned relative to one another such that the pads are longitudinally spaced apart along the wire. While the variation shown may accommodate four individual traces (or wires aligned on the same surface of the substrate,FIGS. 9C to 9Eshow cross-sectional end and top views of another variation of an assembly which may accommodate multiple traces34(e.g., four traces) along an upper surface of substrate32and multiple traces38(e.g., four traces) along a lower surface of substrate32, as previously described. The traces34,38may be correspondingly spaced along the distal portion70and proximal portion72of the assembly such that the traces may be longitudinally aligned on either the upper or lower surface for electrical connection to multiple sensors or components.

As described above, the traces may be formed along either or both of the upper and/or lower surfaces of the substrate32. In another variation, the conductive traces may be formed as a waveguide having active traces and ground traces arranged in various configurations.FIG. 10Ashows a cross-sectional end view of one variation where the active traces80,82,84,86may be aligned in a staggered arrangement over both the upper and lower surfaces of substrate32with ground traces90,92,94,96interspersed in an alternating pattern between the adjacent active traces80,82,84,86. Each of the upper and lower surfaces may be overlaid with coverlay36,40.FIG. 10Bshows another variation where the active traces80,82,84,86may be aligned along the upper surface of substrate32while each of the ground traces90,92,94,96may be aligned along the lower surface while staggered relative to the active traces on the upper surface.

In yet another variation, the assembly may be formed for connection to multiple sensors.FIG. 11Ashows one variation in a cross-sectional end view where active traces80,84may be aligned on the upper surface and active traces82,86may be aligned on the lower surface of substrate32such that these active traces are aligned alternatingly relative to a first edge of the substrate32. The sensor traces100,104may be aligned on the upper surface adjacent to one another while sensor traces102,106may be aligned on the lower surface adjacent to another such that these sensor traces are aligned alternatingly relative to a second edge of the substrate32which is opposite to the first edge.

In another variation as shown in the cross-sectional end view ofFIG. 11B, each of the active traces80,82,84,86may be aligned along the upper surface and the sensor traces100,102,104,106may be aligned along the lower surface such that the active and sensor traces are arranged in an alternating pattern.

With the electrical traces or flat wire formed, the assembly may then be integrated within a guidewire assembly. In one method, the flat wire or flex wire assembly may be attached to a core wire110such that the distal pad assembly116is aligned near or at distal end of the core wire110, e.g., along the reduced distal section114of the core wire110such that the exposed pads face away from the surface of the distal section114. The traces or wires118extending from the distal pad assembly116may be wound or wrapped around the core112, as shown in the side view ofFIG. 12A. Conductive ring elements120,122,124,126may be positioned over the distal section114of the core wire110and over the distal pad assembly116such that each ring element120,122,124,126corresponds to each conductive pads1d,2d,3d,4dalong the distal pad assembly116, as shown inFIG. 12B. The ring elements may be soldered or otherwise attached via a conductive adhesive (such as conductive epoxy) such that each ring element is in electrical communication with each respective conductive pad, as shown inFIG. 12C. The ring elements may be formed to maintain distances between adjacent ring elements to within 50 μm accuracy. The distance between each ring element may be uniform or arbitrary or they may be set at specified distances. For instance, the distance between ring element120and122may be set at, e.g., 1.6 mm, the distance between ring element122and124may be set at, e.g., 1.3 mm, and the distance between ring element124and126may be set at, e.g., 1 mm.

The ring elements120,122,124,126may be made of any metal or conductive material and may serve as an electrode terminal exposed along the guidewire surface. The end128of the distal section114may also be cut to length depending upon the desired length of the core wire110. With the ring elements desirably positioned and attached along the distal section114, an electrically insulative polymer130may be reflowed or molded in-between the ring elements120,122,124,126and the resulting electrode assembly may be sized (e.g., via center-less grinding, laser ablation, etc.) to yield a seamless transition between the ring surface and polymer130to produce an electrode assembly upon the guidewire, as shown inFIG. 12D.

In another variation, rather than utilizing an electrically insulative polymer130, pre-cut and pre-sized polymeric spacers140,142,144,146,148may be positioned upon the distal section114in-between each of the ring elements120,122,124,126to electrically isolate the resulting electrodes, as shown in the side view ofFIG. 13A.

In yet another variation, rather than forming the electrode assembly directly upon the core wire, an electrode subassembly150may be assembled separately and then attached to the core wire.FIG. 13Bshows a side view of one variation where a separate base tube152(e.g., polyimide or other polymer, insulated metal, etc.) may be formed with the distal pad assembly116and ring elements120,122,124,126, as previously described. Traces or wires118may be seen extending from the distal pad assembly116located within the ring elements. In this variation, base tube152may also include the polymeric spacers142,144,146,148positioned and secured between the adjacent ring elements. Alternatively, electrode subassembly150′, as shown in the side view ofFIG. 13C, may be similarly formed but without the polymeric spacers.

In either case, the electrode subassembly150′ may be positioned collinearly at the distal end of the distal section114of core wire112such that the distal end162of core wire112is in direct apposition with the proximal end164of electrode subassembly150′, as shown in the side view ofFIG. 14A. A collar160(e.g., stainless steel, nitinol, etc.) may be positioned to surround the distal section114of core wire112and the proximal section of subassembly150′ such that the interface between distal section114and proximal end162is contained within the collar160. The traces or wires118extending from subassembly150′ may be passed through the interior of collar160and secured around the core wire112. This interface, as well as the portions of the distal section114and subassembly150′ may be secured within the collar160through any number of mechanisms, e.g., solder, adhesive, crimping, etc., such that the core wire112and subassembly150′ are joined to one another in a secure manner.

With the subassembly150′ joined to the core wire112, the portions between the adjacent ring members may be filled with a reflowed or molded polymer166to electrically isolate the adjacent electrodes from one another, as shown in the side view ofFIG. 14B. In the event that subassembly150having the polymeric spacers142,144,146,148is used, as shown in the side view ofFIG. 14C, the attachment between the core wire112and subassembly150may be made without having to reflow any polymer. An additional space168may also be incorporated for the attachment between the subassembly150and collar160. Using either subassembly150or150′, the subassembly (and core wire112) may be sized (e.g., grinding, laser ablation, etc.) to ensure that the transition between the two assemblies is flush and seamless.

Once the electrodes have been formed or attached to the core wire110using any of the methods described herein, the conductive traces or wires118extending from the electrode assembly may be attached to the remainder of the core wire110using a core wire110having a grooved shaft portion170proximal to the distal section114, as shown in the side view ofFIG. 15A. The grooved shaft portion170may extend over a partial length or a majority of the length of the core wire110and define a single helically configured groove172having a first pitch.FIG. 15Bshows a side assembly view with electrode assembly150attached to the distal section114of the core wire110and a proximal electrode assembly174attached to a proximal section of the core wire110. The conductive traces or wires118may be seen wrapped in a helical pattern over the core wire110. As the conductive traces or wires118extend over the grooved shaft portion170, which may have a relatively larger diameter than the remainder of the core wire, the traces or wires118may lie within the groove172over the length of the core wire110, as shown inFIG. 15B.

The traces or wires118may be wound directly over the portions of the core wire which have a relatively smaller diameter than the grooved shaft portion170. With the electrode assemblies and traces or wires118positioned, the distal coil assembly176may be attached to the distal end of the core wire110and the distal portion of the core wire110having the traces or wires118wound directly upon the core wire surface may have a polymer material reflowed upon the assembly to secure it. A covering178, such as a heat shrink covering made of polyethylene terephthalate (PET), may be disposed over the shaft portion170of the core wire over the traces or wires118positioned within the grooves172, as shown in the side view ofFIG. 15C. Optionally, the covering178may disposed over the entire length of the core wire assembly. With the traces or wires118positioned within the groove172, the resulting guide wire assembly may present a smooth outer surface.

While the traces or wires118may be wound upon the core wire at a uniform pitch, they may also be wound upon the core wire at a variable pitch.FIG. 16Ashows a side view of one variation where a distal portion of the traces or wires118may be wound along the distal portion of the core wire where the electrodes are positioned at a second pitch180which is higher and more tightly wound than the first pitch over the remainder of the core wire. The proximal end of the traces or wires118where the proximal electrode assembly is positioned upon the core wire may be wound at a third pitch182which may be equal to the second pitch180at the distal end or different from either the first or second pitch.FIGS. 16B and 16Cshow cross-sectional end views of the second pitch180and third pitch182illustrating the core wire184, an insulative tubing186positioned over the core wire184, and the relatively tightly wound traces or wires118.

FIG. 17Ashows an example of a cross-sectional side view of a core wire having the traces or wires118wound helically upon the outer surface of the core wire and examples of distal ring elements190secured over the distal portion of the traces or wires118as well as proximal ring elements192secured over the proximal portion of the traces or wires118where the ring elements190,192may be secured upon the assembly utilizing any of the methods described herein.FIG. 17Bshows a cross-sectional side view of an example of the resulting overall assembly of the core wire having the wound traces or wires118, ring elements190,192secured upon the assembly, distal coil176attached, and covering178disposed over the shaft portion170, as described above. An additional hydrophilic coating194may be disposed over the entire length of the guide assembly assembly.

Generally,FIG. 18shows a flow diagram of a summary of one variation for assembling the resulting guide wire which may be implemented utilizing any of the methods described herein. Once the core wire and electrode assembly for the distal end of the core wire are assembled together200, the conductive traces or wires may be wound upon the core wire202at a uniform pitch or variable pitches. The electrode assembly for the proximal end of the core wire may also be assembled204. The distal coil may then be attached206to the core wire. The main shaft of the core wire may then have a heat shrink covering disposed upon the core wire208and the distal and proximal ends of the core wire having the traces or wires positioned over the outer surface of the core wire may have a polymer reflowed upon them210. An additional hydrophilic coating212may be applied over the guidewire assembly and the electrodes and the hydrophilic coating (and/or heat shrink coating if also applied over the distal and/or proximal electrode assemblies) may then be removed from over the electrode assemblies214for use.

In yet another variation for assembling the resulting guide wire,FIG. 19shows a flow diagram which may also utilize any of the methods as described herein. Similar to the flow diagram shown inFIG. 18, the core wire and electrode assembly for the distal end (and/or proximal end) of the core wire may be assembled together220. The ring elements may be attached soldered222to form electrodes, as previously described. The portions of the core wire between the ring elements and over the portions of the core wire having the traces or wires may have a polymer reflowed224and the assembly may then have a hydrophilic coating applied over the entire guidewire assembly226. The portions of the hydrophilic coating over the ring elements/electrodes may then be removed to expose the electrodes228for use.

The applications of the devices and methods discussed above are not limited to use in guidewires but may include use in any number of other instruments. Modification of the above-described assemblies and methods for carrying out the invention, combinations between different variations as practicable, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the claims.