Electromagnetic Tracking Sensor with Flexible Core and Method for Manufacturing the Same

Abstract

An electromagnetic tracking sensor for a medical device includes a flexible hollow cylindrical core having an inner surface and an outer surface. The flexible hollow cylindrical core has a layer of magnetic material attached to the inner surface of the flexible hollow cylindrical core. A coil is adjacent to the outer surface of the flexible hollow cylindrical core and circumferentially surrounds the outer surface of the flexible hollow cylindrical core.

Description

[0001] Cross - reference to related applications

[0002] None. Technical field

[0003] The present invention relates to an electromagnetic tracking sensor, and more particularly, to an electromagnetic tracking sensor having a flexible core. Background art

[0004] Inductors and transformers are typically composed of magnetic core materials such as iron, nickel, or iron - containing materials. The magnetic core allows for a higher inductance to be generated in a smaller volume and improves the magnetic coupling between coils. The problem with most magnetic materials is that they are rigid and thus cannot undergo significant mechanical deformation without permanent damage.

[0005] Another example of a device with a magnetic core is a tracking sensor used with an elongate invasive medical device such as a catheter, guide wire, sheath, or core wire. For example, such a tracking coil can be used to determine the position of the distal end of an elongate invasive medical device within a patient's body, enabling position determination for diagnostic purposes. Tracking sensors with a rigid magnetic core surrounded by a coil are known for medical applications. However, it has been found that even with very small axial or torsional deflections, the rigid core can break, thus reducing the sensing ability of the tracking sensor, if not rendering it completely inoperable.

[0006] There is a need in the art for an electromagnetic tracking sensor that can have a flexible hollow core and / or a core having channels formed in the core surface to improve the flexibility of the core and the resulting electromagnetic tracking sensor. Summary of the invention

[0007] The present invention provides an electromagnetic tracking sensor that can have a flexible hollow core and / or a core having channels formed in the core surface to improve the flexibility of the core and the resulting electromagnetic tracking sensor.

[0008] One form of the present invention relates to an electromagnetic tracking sensor for a medical device, the medical device including a flexible hollow cylindrical core having an inner surface and an outer surface. The flexible hollow cylindrical core has a layer of magnetic material attached to the inner surface of the flexible hollow cylindrical core. A coil is adjacent to the outer surface of the flexible hollow cylindrical core and circumferentially surrounds the outer surface of the flexible hollow cylindrical core.

[0009] Another form of the present invention relates to a method of manufacturing an electromagnetic tracking sensor, including providing a flexible polymer substrate having a thickness defined by a first surface spaced apart from a second surface and a width defined by a first longitudinal edge spaced apart from a second longitudinal edge; forming a magnetic material layer on the flexible polymer substrate by adhering a magnetic powder material to the first surface of the flexible polymer substrate; forming a hollow cylindrical core by positioning the first longitudinal edge of the flexible polymer substrate near the second longitudinal edge of the flexible polymer substrate, wherein the magnetic material layer is located inside the hollow cylindrical core; and winding a wire around the outside of the hollow cylindrical core to form a coil adjacent to the second surface of the flexible polymer substrate of the hollow cylindrical core and circumferentially surrounding the second surface of the flexible polymer substrate of the hollow cylindrical core.

[0010] Another form of the present invention relates to an invasive medical device including a flexible elongate member having a distal portion. A flexible electromagnetic tracking sensor is connected to the distal portion of the elongate member. The flexible electromagnetic tracking sensor includes a flexible hollow cylindrical core having an inner surface and an outer surface, and a magnetic material layer attached to the inner surface of the flexible hollow cylindrical core. A coil is adjacent to the outer surface of the flexible hollow cylindrical core and circumferentially surrounds the outer surface of the flexible hollow cylindrical core.

[0011] Another form of the present invention relates to an invasive medical device having a flexible elongate member having a distal portion. A flexible electromagnetic tracking sensor is connected to the distal portion of the elongate member. The electromagnetic tracking sensor includes a flexible iron core having an outer surface. The outer surface includes a plurality of channels. A coil is adjacent to the outer surface of the flexible core and circumferentially surrounds the outer surface of the flexible core.

[0012] One advantage of the present invention is that, compared with an electromagnetic tracking sensor having a non-flexible core, the flexible electromagnetic tracking sensor of the present invention with a flexible core is less likely to be damaged during use for tracking an invasive medical device.

[0013] Another advantage is that, compared with an electromagnetic tracking sensor having a non-flexible core, the flexible electromagnetic tracking sensor of the present invention with a flexible core provides improved tracking performance when used to track the position of a flexible elongate invasive medical device (such as a catheter) through a tortuous path (such as a blood vessel), because the flexible electromagnetic tracking sensor can bend and flex as the flexible elongate invasive medical device passes through the tortuous path. Description of the Drawings

[0014] The above and other features and advantages of the present invention and the manner of achieving them will become more apparent, and the present invention will be better understood by reference to the following description of embodiments of the present invention in conjunction with the drawings, in which:

[0015] Figure 1Schematic diagram of an electromagnetic device tracking system for an invasive medical device having an electromagnetic (EM) field generator, a sensing circuit, and a flexible electromagnetic tracking sensor configured in accordance with one aspect of the present invention;

[0016] Figure 2 is Figure 1 An enlarged side view of the flexible electromagnetic tracking sensor of;

[0017] Figure 3 is Figure 1 A further enlarged end view of the flexible electromagnetic tracking sensor of;

[0018] Figure 4 is Figure 3 taken along line 4-4 of Figure 1 A cross-sectional view of the flexible electromagnetic tracking sensor of;

[0019] Figure 5 is a flowchart depicting a method of manufacturing Figure 1 the flexible electromagnetic tracking sensor of;

[0020] Figure 6 is an illustration of a spin coating process for forming a magnetic material layer on a substrate and forming the substrate onto a flexible hollow cylindrical core according to one aspect of the method depicted in the flowchart of Figure 5 ;

[0021] Figure 7 is an illustration of a screen printing process for forming a magnetic material layer on a substrate and forming the substrate onto a flexible hollow cylindrical core according to one aspect of the method depicted in the flowchart of Figure 5 ;

[0022] Figure 8 is Figure 6 and Figure 7 An enlarged end view of the assembled flexible hollow cylindrical core of;

[0023] Figure 9 is Figure 8 A side view of the assembled flexible hollow cylindrical core of;

[0024] Figures 10A - 10F shows a side view of an alternative flexible iron core having various patterns of a plurality of channels formed in the outer surface of the core to improve flexibility, which can replace the flexible hollow cylindrical core of the flexible electromagnetic tracking sensor as shown in Figures 1 - 4 wherein:

[0025] Figure 10A is a side view of the flexible iron core, wherein the plurality of channels are in the form of a plurality of ellipses formed in the outer surface of the cylindrical circumference surrounding the flexible iron core;

[0026] Figure 10Bis a side view of a flexible iron core, where multiple channels are in the form of multiple S-shaped grooves formed in the outer surface of the cylindrical circumference surrounding the flexible iron core;

[0027] Figure 10C is a side view of a flexible iron core, where multiple channels are in the form of multiple helical grooves formed in the outer surface of the cylindrical circumference surrounding the flexible iron core;

[0028] Figure 10D is a side view of a flexible iron core, where multiple channels are in the form of multiple T-shaped grooves formed in the outer surface of the cylindrical circumference surrounding the flexible iron core;

[0029] Figure 10E is a side view of a flexible iron core, where multiple channels are in the form of multiple staggered radial grooves formed in the outer surface of the cylindrical circumference surrounding the flexible iron core; and

[0030] Figure 10F is a side view of a flexible iron core, where multiple channels are in the form of multiple V-shaped grooves formed in the outer surface of the cylindrical circumference surrounding the flexible iron core.

[0031] Corresponding reference numerals indicate corresponding parts in several views. The example illustrations listed herein illustrate at least one embodiment of the present invention, and these examples should not be construed as limiting the scope of the present invention in any way. Detailed Description

[0032] Now referring to the drawings, and more particularly to Figure 1 , there is shown an electromagnetic device tracking system 10 having an electromagnetic (EM) field generator 12, a sensing circuit 14, and an invasive medical device 16 configured to include a flexible electromagnetic tracking sensor 18 according to one aspect of the present invention.

[0033] The EM field generator 12 is typical as known in the art. In practice, the EM field generator 12 is placed near the area of interest of the patient and is used to triangulate the position of one or more tracking elements (i.e., the flexible electromagnetic tracking sensor 18) disposed on or in the invasive medical device 16. The EM field generator 12 can be, for example, the field generator of an electromagnetic tracking system available from Northern Digital Inc. (NDI), which generates a base electromagnetic field radiating in a known orientation to facilitate electromagnetic space measurement.

[0034] The invasive medical device 16 includes a flexible elongate member 20. The invasive medical device 16 can be, for example, a catheter, a sheath, or a guide wire.

[0035] In Figure 1In the present embodiment depicted, the invasive medical device 16 is in the form of a catheter, which further includes a body 22 connected to a flexible elongate member 20. The body 22 may include ports, such as a fluid port 22-1, an electrical connection port 22-2, and an auxiliary port 22-3. The fluid port 22-1 may be used to facilitate connection to a fluid source (not shown), such as a saline source. The electrical connection port 22-2 may be used to facilitate electrical connection to the flexible electromagnetic tracking sensor 18. The flexible elongate member 20 is configured such that, for example, its size and shape are adapted to be inserted into a patient. The flexible elongate member 20 has a distal portion 20-1 that terminates at a distal tip 20-2.

[0036] In the present embodiment, the flexible electromagnetic tracking sensor 18 is mounted on the distal portion 20-1 of the invasive medical device 16 near the distal tip 20-2. In the context of the previous sentence, the term "near" is in the range of 0 to 2 centimeters (cm), and the extension of the distal portion 20-1 is in the range of 1 millimeter (mm) to 3 cm. However, those skilled in the art will recognize that the exact placement of the flexible electromagnetic tracking sensor 18 on the invasive medical device 16 will depend on the portion of the invasive medical device 16 to be tracked. Due to the interaction between the EM field generator 12 and the flexible electromagnetic tracking sensor 18, the flexible electromagnetic tracking sensor 18 allows determination of the position of the invasive medical device 16.

[0037] The flexible electromagnetic tracking sensor 18 can be used to generate position data defining five degrees of freedom based on the EM field generated by the EM field generator 12. The five degrees of freedom are the X-axis, Y-axis, Z-axis, pitch, and yaw. If desired, a sixth degree of freedom, i.e., roll, can also be included.

[0038] The flexible electromagnetic tracking sensor 18 of the invasive medical device 16 is communicatively coupled to the sensing circuit 14 via a cable 24. The sensing circuit 14 may include a processor circuit configured to execute program instructions to process the electrical signals received from the flexible electromagnetic tracking sensor 18 to determine the position of the flexible electromagnetic tracking sensor 18 relative to the field generated by the EM field generator 12, and may in turn associate the position information with a 2D or 3D imaging space, as is known in the art.

[0039] In the present example, the flexible electromagnetic tracking sensor 18 is connected to the distal portion 20-1 of the flexible elongate member 20 for medical device applications. The flexible electromagnetic tracking sensor 18 can be fully or partially embedded in the flexible elongate member 20, or can be attached to the flexible elongate member 20 by an adhesive.

[0040] Also referring Figures 2 - 4 to, in the present embodiment, the flexible electromagnetic tracking sensor 18 includes a flexible hollow cylindrical core 26 and coils 28.

[0041] The flexible hollow cylindrical core 26 has an inner surface 26-1 and an outer surface 26-2. The flexible hollow cylindrical core 26 further includes a magnetic material layer 30 attached to the inner surface 26-1 of the flexible hollow cylindrical core 26.

[0042] The flexible hollow cylindrical core 26 has a side wall 26-3 having a thickness 26-4, wherein the coil 28 is spaced from the magnetic material layer 30 of the flexible hollow cylindrical core 26 by the thickness 26-4 of the side wall 26-3 of the flexible hollow cylindrical core 26. The flexible hollow cylindrical core 26 can be in the form of, for example, a polymer tube.

[0043] The magnetic material layer 30 can be, for example, a ferromagnetic material layer, which is applied to the inner surface 26-1 of the flexible hollow cylindrical core 26. Materials suitable for forming the magnetic material layer 30 include, for example, samarium cobalt containing iron, NdFeB, ferrite, CoFeSiB, CoFeCrSiB, and FeNi alloys that may contain other elements (such as Mn, Mo, Co, Si, and B), where the Ni content ranges from 60-95% of the volume of the material. These materials can be provided in various forms, such as powder-binder mixtures, for forming the magnetic material layer 30.

[0044] For example, the magnetic material layer 30 can be formed as a ferromagnetic material layer, where the ground ferrite powder is applied as a ferromagnetic powder coating to the inner surface 26-1 of the flexible hollow cylindrical core 26. Alternatively, the magnetic material layer 30 can be formed as a ferromagnetic material layer, where the ground ferrite powder is mixed with a polymer binder that is flexible when cured and can be applied, for example, by printing to form a film on the inner surface 26-1 of the flexible hollow cylindrical core 26.

[0045] The coil 28 is adjacent to the outer surface 26-2 of the flexible hollow cylindrical core 26 and circumferentially surrounds the outer surface 26-2 of the flexible hollow cylindrical core 26. The coil 28 can be formed, for example, by winding a wire 28-1 around the outer surface 26-2 of the flexible hollow cylindrical core 26, thereby circumferentially surrounding the outer surface 26-2 of the flexible hollow cylindrical core 26 with multiple turns of the wire 28-1. In some applications, the wire 28-1 can be wound around the outside of the flexible hollow cylindrical core 26 such that the longitudinal ends of the wire coil 28 are tapered relative to the diameter of the central portion of the wire coil 28.

[0046] The wire 28-1 is a wire having an insulating coating to prevent short circuits between adjacent longitudinal and radial windings of the wire 28-1 that form the wire coil 28. In addition, the wire 28-1 is made of a metal conductor having high electrical conductivity, such as copper. The opposite ends of the wire 28-1 form a set of electrical leads 28-2, 28-3 of the coil 28. This set of electrical leads 28-2, 28-3 of the coil 28 is connected to a cable 24 to electrically couple the coil 28 of the flexible electromagnetic tracking sensor 18 to the sensing circuit 14.

[0047] Reference Figure 5 and also reference Figure 6 and Figure 7 depicts a method of manufacturing Figures 2 - 4 the flexible electromagnetic tracking sensor 18 shown in

[0048] At step S100, a flexible polymer substrate 126, such as a polyimide substrate, is provided for forming a flexible hollow cylindrical core 26. The flexible polymer substrate 126 has a first surface 126-1, a second surface 126-2, a sidewall 126-3, a thickness 126-4, a first longitudinal edge 126-5, a second longitudinal edge 126-6, and a width 126-7.

[0049] The thickness 126-4 of the flexible polymer substrate 126 defines the distance by which the first surface 126-1 is spaced apart from the second surface 126-2. The width 126-7 defines the distance by which the first longitudinal edge 126-5 is spaced apart from the second longitudinal edge 126-6.

[0050] At step S102, a magnetic material layer 30 is formed on the flexible polymer substrate 126 by adhering a magnetic powder material 128 to the first surface 126-1 of the flexible polymer substrate 126.

[0051] The step of forming the magnetic material layer 30 can be performed, for example, by spin coating (see Figure 6 ) or screen printing (see Figure 7 ) of the magnetic powder material 128 onto the first surface 126-1 of the flexible polymer substrate 126.

[0052] A polyimide coating can be applied on the magnetic material layer 30. Additionally, if desired, a polyethylene layer can be applied to the second surface 126-2.

[0053] At step S104, a flexible hollow cylindrical core 26 is formed by positioning the first longitudinal edge 126-5 of the flexible polymer substrate 126 adjacent to the second longitudinal edge 126-6 of the flexible polymer substrate 126 such that the magnetic material layer 30 is located inside the flexible hollow cylindrical core 26.

[0054] For example, the step S104 of forming the flexible hollow cylindrical core 26 can be performed by the following sequential sub-steps:

[0055] 1) The flexible polymer substrate 126 is formed into a rectangular flexible polymer substrate 126 having a first longitudinal edge 126-5 spaced apart from the second longitudinal edge 126-6;

[0056] 2) defining a fold line 126-8 between the first longitudinal edge 126-5 and the second longitudinal edge 126-6 (see Figure 6 and Figure 8 ), wherein the fold line separates the rectangular flexible polymer substrate 126 to define a first portion 126 - 9 and a second portion 126 - 10;

[0057] 3) Each of the first portion 126-9 and the second portion 126-10 is rolled into two semi-cylindrical portions 26-5, 26-6 (see Figure 6 and Figure 7 ), for example, symmetrical semi-cylindrical portions, wherein semi-cylindrical portion 26-5 and semi-cylindrical portion 26-6 are separated by fold line 126-8; and

[0058] 4) Folding the rectangular flexible polymer substrate 126 having the semi-cylindrical portions 26-5, 26-6 at the fold line 126-8 to position the first longitudinal edge 126-5 adjacent to the second longitudinal edge 126-6 (see FIG. Figure 8 and Figure 9 ), thereby completing the formation of the shape of the flexible hollow cylindrical core 26, and wherein the second surface 126-2 of the rectangular flexible polymer substrate 126 becomes the outer surface 26-2 of the flexible hollow cylindrical core 26.

[0059] Optionally, the first longitudinal edge 126-5 may be adhered to the second longitudinal edge 126-6, for example, by an adhesive such as epoxy.

[0060] Alternatively, it is contemplated that the step S104 of forming the flexible hollow cylindrical core 26 may be performed by the aforementioned sub-step of defining the fold line 126-8, wherein the rectangular flexible polymer substrate 126 is forced into a cylindrical shape so as to position the first longitudinal edge 126-5 adjacent to the second longitudinal edge 126-6. In doing so, the second surface 126-2 of the rectangular flexible polymer substrate 126 becomes the outer surface 26-2 of the flexible hollow cylindrical core 26.

[0061] At step S106, refer to Figures 2 - 4 , the wire 28-1 is wound around the outside of the flexible hollow cylindrical core 26 to form a wire coil 28 adjacent to and circumferentially surrounding the cylindrical second surface 126-2 of the flexible polymer substrate 126, i.e., adjacent to and circumferentially surrounding the outer surface 26-2 of the flexible hollow cylindrical core 26. In one embodiment, the wire 28-1 can be wound around the outside of the flexible hollow cylindrical core 26 so that the longitudinal ends of the coil 28 are tapered relative to the diameter of the central portion of the coil 28.

[0062] Optionally, further steps may be performed to encapsulate the flexible electromagnetic tracking sensor 18 with an electrically insulating and thermally insulating coating (e.g., a polyimide coating). For example, a coating of insulating material may be applied to any exposed portions of the coil 28 and the second surface 126-2 of the outer surface 26-2 that forms the flexible hollow cylindrical core 26, and if desired, may also be applied to the magnetic material layer 30 that adheres to the first surface 126-1 of the inner surface 26-1 that forms the flexible hollow cylindrical core 26.

[0063] Reference Figures 10A - 10F , as an alternative to the flexible electromagnetic tracking sensor 18 having a flexible hollow cylindrical core 26, it is contemplated that a flexible iron core 200 may replace the flexible hollow cylindrical core 26. Materials suitable for forming the flexible iron core 200 include, for example, samarium cobalt containing iron, NdFeB, ferrite, CoFeSiB, CoFeCrSiB, and FeNi alloys having other elements such as Mn, Mo, Co, Si, and B, where Ni is in the range of 60-95% of the material. These materials may be provided in various forms, such as a powder-binder mixture, for forming the flexible iron core 200.

[0064] The flexible iron core 200 may be a flexible ferrite hollow core configuration or may be in the form of a solid flexible ferrite core. In a hollow core configuration, the entire body of the core may be made of iron material, or an iron material layer may be applied to the inner or outer surface of a polymer tube.

[0065] In Figures 10A - 10F the embodiment shown, the flexibility of the flexible iron core 200 is at least partially attributed to a plurality of channels 202 formed on the outside of the flexible iron core 200. As Figures 10A - 10F shown, for example, the plurality of channels 202 may take the form of a plurality of different groove patterns. Additionally, optionally, as described above, the flexible hollow cylindrical core 26 may be modified to include a plurality of channels 202 on the outer surface 26-2 to further enhance the flexibility of the flexible hollow cylindrical core 26. In all embodiments having a plurality of channels 202, for example, the channel depth may be in the range of, for example, 10 micrometers (μm) to 20,000 μm, and the channel width may be in the range of, for example, 1 μm to 1000 μm.

[0066] Reference Figures 10A - 10F , the flexible iron core 200 has an outer surface 204, where a plurality of channels 202 are formed in the outer surface 204 to enhance the flexibility of the flexible iron core 200. The plurality of channels 202 may be cut, for example, by laser cutting, into the outer surface 204.

[0067] The plurality of channels 202 may extend longitudinally along the flexible iron core 200 and be arranged as a repeating pattern of grooves around the cylindrical circumference of the flexible iron core 200. Advantageously, Figures 10A - 10FEach pattern among the patterns of the plurality of channels 202 depicted promotes longitudinal and torsional flexibility.

[0068] Figure 10A A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of ellipses 202-1 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0069] Figure 10B A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of S-shaped grooves 202-2 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0070] Figure 10C A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of helical grooves 202-3 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0071] Figure 10D A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of T-shaped grooves 202-4 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0072] Figure 10E A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of staggered radial grooves 202-5 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0073] Figure 10F A flexible iron core 200 is shown, where the plurality of channels 202 are in the form of a plurality of V-shaped grooves 202-6 formed in the outer surface 204 of the cylindrical circumference around the flexible iron core 200.

[0074] To complete the construction of the flexible electromagnetic tracking sensor 18 using the flexible iron core 200, a coil 28 adjacent to the outer surface 204 of the flexible iron core 200 and circumferentially surrounding the outer surface 204 of the flexible iron core 200 needs to be formed according to the above process step S106. Also refer to Figure 1 , and then the flexible electromagnetic tracking sensor 18 can be attached, such as, embedded in the distal portion 20-1 of the flexible elongated member 20.

[0075] The following items are also related to the present invention:

[0076] In one form, the present invention relates to an electromagnetic tracking sensor for a medical device. The electromagnetic tracking sensor can include a flexible hollow cylindrical core having an inner surface and an outer surface, and can have a layer of magnetic material attached to the inner surface of the flexible hollow cylindrical core. A coil can be adjacent to the outer surface of the flexible hollow cylindrical core and / or at least partially circumferentially surround the outer surface of the flexible hollow cylindrical core.

[0077] In the embodiment of the preceding paragraph, the flexible hollow cylindrical core has a sidewall having a thickness, and the coil can be spaced from the magnetic material layer of the flexible hollow cylindrical core by the thickness of the sidewall of the flexible hollow cylindrical core.

[0078] In any embodiment having a layer of magnetic material, the layer of magnetic material can be a ferromagnetic material.

[0079] In any embodiment having a layer of magnetic material, the layer of magnetic material can be a ferromagnetic powder coating.

[0080] In any embodiment, the coil can be a copper coil.

[0081] In another form, the present invention relates to a method of manufacturing an electromagnetic tracking sensor, the method can include the following steps: providing a flexible polymer substrate having a thickness defined by a first surface spaced from a second surface and a width defined by a first longitudinal edge spaced from a second longitudinal edge; forming a layer of magnetic material on the flexible polymer substrate by adhering a magnetic powder material to the first surface of the flexible polymer substrate; forming a hollow cylindrical core by positioning the first longitudinal edge of the flexible polymer substrate near the second longitudinal edge of the flexible polymer substrate, wherein the layer of magnetic material can be located inside the hollow cylindrical core; and winding a wire around the outside of the hollow cylindrical core to form a coil adjacent to the second surface of the flexible polymer substrate of the hollow cylindrical core and / or at least partially circumferentially around the flexible polymer substrate of the hollow cylindrical core.

[0082] In the above method, the step of forming the layer of magnetic material can be performed by spin coating or screen printing the magnetic powder material onto one of the first surfaces of the flexible polymer substrate.

[0083] In the method, the step of forming the hollow cylindrical core can include the following sequential steps: forming the flexible polymer substrate into a rectangular flexible polymer substrate having a first longitudinal edge spaced from the second longitudinal edge; defining a fold line between the first longitudinal edge and the second longitudinal edge, the fold line separating the rectangular flexible polymer substrate to define a first portion and a second portion; rolling each of the first portion and the second portion into a semi-cylindrical portion spaced by the fold line; and folding the rectangular flexible polymer substrate at the fold line to position the first longitudinal edge adjacent to the second longitudinal edge.

[0084] Optionally, the method may include adhering the first longitudinal edge to the second longitudinal edge.

[0085] Optionally, the method may include applying a coating of insulating material to any exposed portions of the second surface of the coil and the hollow cylindrical core.

[0086] In another form, the present invention relates to an invasive medical device that may include a flexible elongate member and a flexible electromagnetic tracking sensor having a flexible hollow cylindrical core, namely the flexible electromagnetic tracking sensor of paragraph

[0075] . The flexible elongate member has a distal portion. The flexible electromagnetic tracking sensor may be connected to the distal portion of the elongate member. The flexible electromagnetic tracking sensor may include a flexible hollow cylindrical core and a coil. The flexible hollow cylindrical core has an inner surface and an outer surface, and may have a layer of magnetic material attached to the inner surface of the flexible hollow cylindrical core. The coil may be adjacent to the outer surface of the flexible hollow cylindrical core and / or at least partially circumferentially surround the outer surface of the flexible hollow cylindrical core. Further contemplated embodiments are disclosed in paragraphs

[0076] to

[0079] .

[0087] In another form, the present invention relates to an invasive medical device that may include a flexible elongate member and a flexible electromagnetic tracking sensor having a flexible iron core. The present invention may also relate to a flexible electromagnetic tracking sensor having a flexible iron core, as described below, without a flexible elongate member having a distal portion; and without the need to connect the flexible electromagnetic tracking sensor to the distal portion of the elongate member. The flexible elongate member has a distal portion. The flexible electromagnetic tracking sensor may be connected to the distal portion of the elongate member. The flexible electromagnetic tracking sensor may include a flexible iron core having an outer surface, and wherein the outer surface includes a plurality of channels. The coil may be adjacent to the outer surface of the flexible core and / or at least partially circumferentially surround the outer surface of the flexible core.

[0088] In any embodiment having a flexible elongate member, the flexible elongate member may be one of a catheter, a sheath, and a guide wire.

[0089] In any embodiment having a flexible iron core, the flexible iron core may be one of a flexible hollow cylindrical core and a flexible solid core.

[0090] In any embodiment in which the flexible iron core is a flexible hollow cylindrical core, the flexible hollow cylindrical core has an inner surface and an outer surface, wherein the outer surface may be the outer surface of the flexible core. A ferromagnetic material layer may be attached to the inner surface.

[0091] In any embodiment having a flexible hollow cylindrical core, the flexible hollow cylindrical core has a sidewall having a thickness. In some embodiments, the coil may be spaced from the ferromagnetic material layer of the flexible hollow cylindrical core by the thickness of the sidewall.

[0092] In any embodiment having a ferromagnetic material layer, the ferromagnetic material layer can be a ferromagnetic powder coating.

[0093] In any embodiment, the coil can be a copper coil.

[0094] In any embodiment having a plurality of channels, the plurality of channels can be arranged as a repeating pattern of slots along the longitudinal extent of the flexible iron core.

[0095] In any embodiment having a repeating pattern of slots, the repeating pattern of slots can be one or more of, for example, a plurality of oval slots, a plurality of S-shaped slots, a plurality of helical slots, a plurality of T-shaped slots, a plurality of staggered slots, and a plurality of V-shaped slots.

[0096] In any embodiment having a flexible elongate member, the flexible electromagnetic tracking sensor can be embedded in the distal portion of the flexible elongate member.

[0097] As used herein, the term "flexible" means that an object is capable of withstanding a certain amount of axial deflection and / or torsional deformation without breaking, where the amount can be at least a certain degree of axial deflection and / or torsional deformation.

[0098] As used herein, any degree of a word is a relative modifier and is intended to indicate an allowable variation of the property so modified.

[0099] Although the invention has been described for at least one embodiment, the invention can be further modified within the spirit and scope of the present disclosure. Accordingly, this application is intended to cover any variations, uses, or adaptations of the invention using its general principles. Additionally, this application is intended to cover departures from the present disclosure that come within known or customary practice in the art to which this invention pertains and fall within the limits of the appended claims.

Claims

1. An electromagnetic tracking sensor for a medical device, comprising: a flexible polymer core having an inner surface and an outer surface, and having a layer of magnetic material attached to the inner surface of the flexible polymer core; and a coil adjacent to and circumferentially surrounding the outer surface of the flexible polymer core, wherein the electromagnetic tracking sensor is flexible in the axial and / or torsional directions.

2. The electromagnetic tracking sensor according to claim 1, wherein the flexible polymer core has a sidewall having a thickness, and wherein the coil is spaced from the magnetic material layer of the flexible polymer core by the thickness of the sidewall of the flexible polymer core.

3. The electromagnetic tracking sensor according to any one of claims 1 to 2, wherein the magnetic material layer is a ferromagnetic material.

4. The electromagnetic tracking sensor according to any one of claims 1 to 2, wherein the magnetic material layer is a ferromagnetic powder coating.

5. The electromagnetic tracking sensor according to any one of claims 1 to 2, wherein the coil is a copper coil.

6. The electromagnetic tracking sensor according to any one of claims 1 to 2, wherein the magnetic material layer comprises a mixture of magnetic powder - binder.

7. A method of manufacturing an electromagnetic tracking sensor, comprising: providing a flexible polymer substrate having a thickness defined by a first surface spaced from a second surface and a width defined by a first longitudinal edge spaced from a second longitudinal edge; forming a magnetic material layer on the flexible polymer substrate by adhering a magnetic powder material to the first surface of the flexible polymer substrate; forming a hollow cylindrical core by positioning the first longitudinal edge of the flexible polymer substrate adjacent to the second longitudinal edge of the flexible polymer substrate, wherein the magnetic material layer is located inside the hollow cylindrical core; and wrapping a wire around the outside of the hollow cylindrical core to form a coil adjacent to and circumferentially surrounding the second surface of the flexible polymer substrate of the hollow cylindrical core, wherein the electromagnetic tracking sensor is flexible in the axial and / or torsional directions.

8. The method according to claim 7, wherein the step of forming the magnetic material layer is performed by spin - coating or screen - printing the magnetic powder material onto one of the first surfaces of the flexible polymer substrate.

9. The method according to any one of claims 7 to 8, wherein the step of forming the hollow cylindrical core comprises the following sequential steps: forming the flexible polymer substrate into a rectangular flexible polymer substrate having a first longitudinal edge spaced from a second longitudinal edge; defining a fold line between the first longitudinal edge and the second longitudinal edge, the fold line separating the rectangular flexible polymer substrate to define a first part and a second part; rolling each of the first part and the second part into a semi - cylindrical part spaced by the fold line; and folding the rectangular flexible polymer substrate at the fold line to position the first longitudinal edge adjacent to the second longitudinal edge.

10. The method according to any one of claims 7 to 8, comprising adhering a first longitudinal edge to a second longitudinal edge.

11. The method according to any one of claims 7 to 8, comprising applying a coating of insulating material to any exposed portions of the second surface of the coil and the hollow cylindrical core.

12. An invasive medical device comprising: a flexible elongate member having a distal portion; and a flexible electromagnetic tracking sensor connected to the distal portion of the flexible elongate member, wherein the flexible electromagnetic tracking sensor comprises: a flexible polymer core having an inner surface and an outer surface, and having a layer of magnetic material attached to the inner surface of the flexible polymer core; and a coil adjacent to and circumferentially surrounding the outer surface of the flexible polymer core, wherein the electromagnetic tracking sensor is flexible in the axial and / or torsional directions.

13. The invasive medical device according to claim 12, wherein the flexible polymer core has a sidewall having a thickness, and wherein the coil is spaced from the magnetic material layer of the flexible polymer core by the thickness of the sidewall of the flexible polymer core.

14. The invasive medical device according to any one of claims 12 to 13, wherein the magnetic material layer is a ferromagnetic material.

15. The invasive medical device according to any one of claims 12 to 13, wherein the magnetic material layer is a ferromagnetic powder coating.

16. The invasive medical device according to any one of claims 12 to 13, wherein the coil is a copper coil.

17. The invasive medical device according to any one of claims 12 to 13, wherein the magnetic material layer comprises a mixture of magnetic powder and binder.

18. The invasive medical device according to claim 12, wherein the flexible elongate member is one of a catheter, a sheath, and a guide wire.

19. The invasive medical device according to any one of claims 12 to 13, wherein the flexible electromagnetic tracking sensor is embedded in the distal portion of the flexible elongate member.

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