Ultra-narrow probe with coil

Abstract

To provide a probe apparatus.SOLUTION: In one embodiment, a probe apparatus includes a shaft having a distal end, a tube containing separate powder granules of a ferrite, the tube being fixed to the distal end of the shaft, a coil disposed around the tube, and electrical wires connected to the coil so as to read out a signal generated across the coil by an externally applied magnetic field.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to medical instruments, particularly but not exclusively to probes having navigation features. [Background technology]

[0002] A wide range of medical procedures involve the placement of probes, such as guidewires and catheters, within a patient's body. Position sensing systems have been developed to track such probes. Magnetic position sensing is one method known in the art. In magnetic position sensing, magnetic field generators are typically placed at known locations outside the patient's body. A magnetic field sensor in the distal end of the probe generates electrical signals in response to these magnetic fields, which are processed to determine the coordinate position of the distal end of the probe. These methods and systems are described in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, and 6,332,089, WO 1996 / 005768, and U.S. Patent Application Publication Nos. 2003 / 0120150 and 2004 / 0068178, the disclosures of which are incorporated herein by reference in their entireties.

[0003] Navigable guidewires typically have a diameter on the order of 1 mm or greater, which limits the parts of the body through which they can be inserted to, for example, the tips of the lungs and some blood vessels in the brain.

[0004] U.S. Patent Publication No. 2016 / 0022154 to Warnking et al. describes a system for sensing blood pressure in a blood vessel that includes a guidewire and an LC resonant circuit disposed at a distal end of the guidewire. The resonant circuit may be a non-LC resonant circuit that responds to pressure changes in a fluid external to the guidewire such that the resonant circuit has a resonant frequency that varies in response to pressure changes in the external fluid.

[0005] U.S. Patent Publication No. 2014 / 0371709 to Allen et al. describes a catheter assembly having a catheter body and an inflatable balloon. The catheter body has a proximal end, a distal end, and a balloon inflation lumen. The inflatable balloon is attachable to the distal end of the catheter body. The balloon has an inner surface at least partially defining an interior volume. The balloon is configured such that the interior volume is in fluid communication with the inflation lumen of the catheter body to inflate the balloon. The balloon also has a proximal surface and a distal surface. The balloon is provided with a channel extending therethrough. The channel is configured to provide fluid communication between the proximal surface of the balloon and the distal surface of the balloon. Other catheter assemblies and methods of use are also disclosed.

[0006] U.S. Patent Publication No. 2019 / 0022363 to Grayzel et al. describes a medical guide element for use with a dilator for insertion into a patient's organ or body structure, such as a kidney. The guide element includes a proximal segment and a distal segment. The diameter of the distal segment is greater than the diameter of the proximal segment. When a discrete step transition occurs at a point along the filament, as exhibited by a proximally facing surface on the distal segment, the change in diameter is abrupt. When the proximal segment of the guide element is fully inserted into a dilator having a distal tip adapted for insertion into a patient, the distal tip of the dilator firmly contacts the proximally facing end surface of the distal segment. The relative dimensions of the tip of the dilator and the discrete step transitions of the guide element provide complete or full shielding of the dilator tip, facilitating passage of the dilator tip along the tissue tracker from the puncture hole into the orifice. Summary of the Invention [Means for solving the problem]

[0007] According to an embodiment of the present disclosure, a probe apparatus is provided that includes a shaft having a distal end, a tube containing loose powdered granules of ferrite, the tube being secured to the distal end of the shaft, a coil disposed around the tube, and electrical wires connected to the coil for reading a signal generated across the coil by an externally applied magnetic field.

[0008] Furthermore, according to an embodiment of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0009] According to a further embodiment of the present disclosure, the device includes a guidewire including a solid rod core wire including a distal end and a surface channel for accommodating an electrical wire therein, a moldable elongate member connected to the distal end of the core wire and configured to retain its shape after deformation, and an elastic elongate member disposed about the moldable elongate member, with a tube disposed distal to the elastic elongate member and the moldable elongate member.

[0010] Furthermore, in accordance with an embodiment of the present disclosure, the surface channel spirals around the core wire away from the distal end of the core wire.

[0011] Further, in accordance with an embodiment of the present disclosure, the moldable elongate member includes a flattened wire helical spring.

[0012] Further, in accordance with an embodiment of the present disclosure, the resilient elongate member includes an exterior surface including a plurality of cut grooves disposed about a periphery of the exterior surface.

[0013] Still further in accordance with an embodiment of the present disclosure, the guidewire includes a shrink sleeve disposed over the corewire that secures the electrical wires to the surface channels.

[0014] Furthermore, in accordance with an embodiment of the present disclosure, the tube is formed from plastic.

[0015] Furthermore, according to an embodiment of the present disclosure, the plastic includes polyimide.

[0016] According to another embodiment of the present disclosure, there is also provided a position tracking system including a probe configured to be inserted into a body part of a living subject, the probe including a shaft having a distal end, a tube containing loose powdered granules of ferrite, the tube being secured to the distal end of the shaft, a coil disposed around the tube, and an electrical wire connected to the coil to read a signal generated across the coil by an applied magnetic field, a location pad having at least one magnetic field emitter configured to transmit an alternating magnetic field to an area where the body part is located, and a processing circuit connected to the electrical wire, the processing circuit configured to receive a signal from the coil and calculate a position and orientation of the distal end in response to the received signal.

[0017] Furthermore, according to an embodiment of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0018] Still further in accordance with an embodiment of the present disclosure, the probe includes a guidewire including a solid rod core wire including a distal end and a surface channel for accommodating an electrical wire therein, a moldable elongate member connected to the distal end of the core wire and configured to retain its shape after deformation, and an elastic elongate member disposed around the moldable elongate member, with a tube disposed distal to the elastic elongate member and the moldable elongate member.

[0019] Furthermore, in accordance with an embodiment of the present disclosure, the tube is formed from plastic.

[0020] Furthermore, according to an embodiment of the present disclosure, the plastic includes polyimide.

[0021] According to yet another embodiment of the present disclosure, there is also provided a method of manufacturing a magnetic coil, the method including introducing loose powder granules of ferrite into a tube and disposing a coil around the tube.

[0022] Furthermore, according to an embodiment of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0023] Still further according to an embodiment of the present disclosure, while the powdered granules are being introduced into the tube, the tube has an outer diameter larger than the inner diameter of the coil, and the method further includes heat shrinking the tube to have an outer diameter smaller than the inner diameter of the coil.

[0024] Further according to an embodiment of the present disclosure, the method includes suspending powdered granules in a liquid, disposing a tube in the liquid such that a portion of the liquid containing the powdered granules is drawn into the tube by capillary action, and evaporating the liquid from the tube.

[0025] Further, according to an embodiment of the present disclosure, the liquid is alcohol.

[0026] Furthermore, in accordance with an embodiment of the present disclosure, the tube is formed from plastic.

[0027] Still further according to an embodiment of the present disclosure, the plastic comprises polyimide. [Brief description of the drawings]

[0028] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1A] 1 is a schematic diagram of a probe-based cerebrovascular position tracking system according to an embodiment of the present invention. [Figure 1B] 1 is a schematic diagram of a probe-based cerebrovascular position tracking system according to an embodiment of the present invention. [Diagram 2] FIG. 1C is a schematic diagram of a probe for use in the system of FIG. 1A or FIG. 1B. [Diagram 3] FIG. 3 is a schematic diagram of elements of the probe of FIG. 2. [Figure 4A] 1C is a flow chart including steps in a method of manufacturing a magnetic coil for use in the system of FIG. 1A or FIG. 1B. [Figure 4B]FIG. 4B is a schematic diagram illustrating the manufacturing method described with reference to the flow chart diagram of FIG. 4A. [Figure 4C] FIG. 4B is a schematic diagram illustrating the manufacturing method described with reference to the flow chart diagram of FIG. 4A. [Figure 4D] FIG. 4B is a schematic diagram illustrating the manufacturing method described with reference to the flow chart diagram of FIG. 4A. [Figure 5A] 1C is a flow chart including steps in an alternative method of manufacturing a magnetic coil for use in the system of FIG. 1A or FIG. 1B. [Figure 5B] FIG. 5B is a schematic diagram illustrating an alternative manufacturing method described with reference to the flow chart diagram of FIG. 5A. [Figure 5C] FIG. 5B is a schematic diagram illustrating an alternative manufacturing method described with reference to the flow chart diagram of FIG. 5A. [Figure 5D] FIG. 5B is a schematic diagram illustrating an alternative manufacturing method described with reference to the flow chart diagram of FIG. 5A. [Figure 5E] FIG. 5B is a schematic diagram illustrating an alternative manufacturing method described with reference to the flow chart diagram of FIG. 5A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Overview As already mentioned, navigable probes such as guidewires typically have a diameter on the order of 1 mm or more, which limits the parts of the body into which they can be inserted to, for example, the tip of the lung and some blood vessels in the brain.

[0030] Making smaller diameter probes, i.e., below 0.9 mm, such as about 300 microns or less, is not simply a matter of miniaturization by making the various elements of the probe smaller and smaller. One such challenge is producing a small enough magnetic core for the probe's navigation coils.

[0031] For example, magnetic antennas can use magnetic cores made of ferromagnetic or ferrimagnetic materials, such as iron or nickel-zinc ferrite or magnesium-zinc ferrite, to increase the permeability. The magnetic cores can increase the antenna sensitivity by up to several thousand times by increasing the magnetic field due to their higher magnetic permeability. Thus, coils used in navigable probes typically include coils with magnetic cores. Solid magnetic cores can be constructed by any suitable method, including binding magnetic core powders using binders and / or very high temperatures (sintering) to form a solid mass. However, the above manufacturing methods are generally not suitable for producing solid magnetic cores small enough to be inserted into coils having an inner diameter of about 500 microns or less.

[0032] An embodiment of the present invention provides a probe that includes a shaft having a distal end and a tube secured to the distal end of the shaft. The tube contains loose powdered granules of ferrite and the coil is placed around the tube, for example, by inserting the tube into the coil. The coil is then covered with a sheath that keeps the coil in place and acts as a biocompatible cover. The wire used for the coil can have any suitable gauge, for example, but not limited to, 60 gauge, which is about 8 microns in diameter. The powdered granules are held in place by the tube. The powdered granules are not fired to form a single mass, but may be bonded together using a bonding material such as an epoxy. The tube may be formed from any suitable material, such as a wide range of thermoplastics, for example, polyimide, polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP) or polyvinyl chloride (PVC), or other materials such as developed ceramics, carbon materials or non-ferromagnetic metals. The tube provides a controlled outer diameter surface over which the coil slides.

[0033] Electrical wires connect to the coil to read a signal generated across the coil by an externally applied magnetic field. The signal produced by the coil is used to calculate the position and orientation of the distal end of the probe. The powdered granules increase the magnetic permeability of the coil, thereby increasing the amplitude of the signal produced by the coil.

[0034] The powdered granules can have a size of about 40 microns, making it difficult to place the powdered granules in a tube that may have an inner diameter down to 100 in some embodiments. In some cases, the powdered granules have a size approximately the same as the radius of the tube. The present invention, in its embodiments, provides a novel method for introducing the powdered granules into a tube.

[0035] As used herein, the term "about" or "approximately" in reference to any numerical value or range of values ​​indicates an appropriate and suitable dimensional tolerance that enables a portion of a component or a collection of components to function according to its intended purpose as described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±20% of the recited value, for example, "about 90%" may refer to a range of values ​​of 71% to 99%.

[0036] In some embodiments, the powdered granules are placed into a heat shrinkable tube having an outer diameter larger than the inner diameter of the coil. For example, the powdered granules may be placed into a tube having an inner diameter of about 180 microns and an outer diameter of about 250 microns. It is much easier to place the powdered granules into a tube having an inner diameter of about 180 microns than into a tube having an inner diameter of 150 microns or less. Heat is then applied to the tube to heat shrink the tube until the outer diameter is equal to the inner diameter of the coil. The heat shrunk tube is then inserted into the coil. The tube may be formed from any suitable material, such as a wide range of thermoplastics, for example, polyimide, polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP), or polyvinyl chloride (PVC).

[0037] In some embodiments, the powdered granules are suspended in a liquid, such as alcohol, e.g., isopropyl alcohol, using, for example, a vibrating table. The end of a tube having an outer diameter smaller than the inner diameter of the coil is then placed in the liquid, and the suspension of powdered granules is drawn into the tube by capillary action. An evaporation process is then started to evaporate the liquid in the tube, leaving the powdered granules in the tube. The filled tube of powdered granules is inserted into the coil. The tube may be formed from any suitable material, such as a wide range of thermoplastics, e.g., polyimide, polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP), or polyvinyl chloride (PVC).

[0038] System Description Documents incorporated herein by reference are to be considered as integral parts of this application and, unless any term is defined in those incorporated documents to the contrary, either expressly or impliedly, in this specification, only the definition in this specification should be considered.

[0039] 1A and 1B are schematic diagrams of probe-based cerebrovascular position tracking systems 20a and 20b, according to an embodiment of the present invention.

[0040] In some embodiments, a CT image of the patient 32 is acquired prior to performing the medical procedure. The CT image is stored in memory 42 by processing circuitry 40 for subsequent retrieval. Processing circuitry 40 uses the image to present, for example, a brain cross-sectional image 59 on display 56. In another embodiment, during the disclosed medical procedure, tracking systems 20a and 20b align the position and orientation of the distal end of probe 28 within the patient's brain with a frame of reference of a brain image of patient 32, which is assumed herein to include, by way of example, a real-time fluoroscopic image. The position and orientation of the distal end of probe 28 is tracked using a magnetic tracking subsystem 23, which tracks the position and orientation coordinates of a magnetic sensor mounted on the distal end of probe 28. The magnetic tracking subsystem 23 may form part of the tracking subsystem 33. The physician 54 uses the magnetic position and orientation tracking subsystem 23 to advance the distal end of probe 28 from the vessel.

[0041] In the system 20a shown in FIG. 1A, the localization pad 24a included in the magnetic tracking subsystem 23 is implemented as a collar around the neck of the patient 32. By placing the localization pad 24a around the neck, the localization pad 24a is configured to automatically compensate for the patient's head movement. The localization pad 24a includes a magnetic field emitter 26a, which is fixed in a fixed position relative to the head of the patient 32 and transmits an alternating sinusoidal magnetic field to the area 30 where the head of the patient 32 is located. The console 50 electrically drives the emitter 26a via cable 25. In an embodiment, the head movement is further compensated for by attaching a reference sensor 21 to the patient's forehead. The console 50 is configured to receive a signal from the reference sensor 21 via cable 27. A position tracking system including a cervical collar location pad is described in U.S. patent application Ser. No. 16 / 248,393, filed Jan. 15, 2019, entitled "Position Sensor on Brain Clot Sheath and Location Pad Collar," which is assigned to the assignee of this patent application, the disclosure of which is incorporated herein by reference.

[0042] A physician 54 operating the system 20a holds a controller handle 29 connected to the proximal end of the probe 28. The controller handle 29 enables the physician to enter and navigate the probe 28 into the brain, for example from an entry point 22 in the femoral artery of the patient 32. As described above and below, the physician 54 navigates the distal end of the probe 28 using position and orientation signals from a magnetic sensor mounted on the distal end of the probe 28. The console 50 receives the magnetic sensor signals via a cable 19 that connects to the probe 28 through the handle 29.

[0043] The elements of the system 20a, including the emitter 26a, are controlled by a processing circuit 40, which comprises a processing unit in communication with one or more memories (e.g., memory 42). The processing circuit 40 may be mounted in a console 50 with operational controls 58, typically including a keypad and / or a pointing device such as a mouse or trackball. A physician 54 can use the operational controls on a handle 29 to interact with the processing circuit 40 while simultaneously registering the system 20a. During the registration process, a brain cross-sectional image 59 is displayed on a display 56. Following the registration process described above, the physician 54 uses the operational controls to advance the distal end of the probe 28 to one or more desired locations within the brain.

[0044] The processing circuitry 40 operates the system 20a using software stored in memory 42. In practice, some or all of the functionality of the processing circuitry 40 may be integrated into a single physical component, or alternatively implemented using multiple physical components. These physical components may comprise hardwired or programmable devices, or a combination of the two. In some embodiments, at least some of the functionality of the processing circuitry 40 may be performed by a programmable processor under the control of suitable software. The software may be downloaded to the device in electronic form, for example over a network. Alternatively or additionally, the software may be stored in a tangible, non-transitory computer-readable medium, such as optical, magnetic, or electronic memory.

[0045] System 20b shown in FIG. 1B has a different magnetic localization pad design, namely localization pad 24b. As can be seen, localization pad 24b is fixed to the bed and illuminator 26b surrounds the patient's headrest horizontally. In this example, system 20b does not have a reference sensor 21, and therefore the patient's head must be fixed to prevent head movement. Other components of system 20b are generally identical to those of system 20a. A position tracking system using a localization pad similar to localization pad 24b is described in U.S. Patent Application No. 15 / 674,380, filed August 10, 2017, entitled "ENT Image Registration," which is assigned to the assignee of the present patent application and the disclosure of which is incorporated herein by reference.

[0046] The systems 20a and 20b shown in Figures 1A and 1B have been selected solely for purposes of conceptual clarity, and additional controls may be included on the handle 29 to control other system elements, e.g., additional devices, such as for drug delivery.

[0047] The CARTO® magnetic tracking system is manufactured by Biosense-Webster (Irvine, California) which uses technology similar to that applied by systems 20a and 20b to track the position and orientation of magnetic position sensors within body organs. In general, position sensing using current distribution measurements and / or external magnetic fields is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612, 6,332,089, 7,756,576, 7,869,865 and 7,848,787, WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455(A1), 2003 / 0120150(A1) and 2004 / 0068178(A1), the disclosures of which are all incorporated herein by reference.

[0048] The above description describes navigating a probe in the blood vessels of the brain. Systems 20a and 20b may be suitably adapted to navigate a probe in a suitable body part within a living subject, for example, within the sinuses, the heart, or the kidneys. Probe 28 may be implemented as any suitable probe equipped with a magnetic coil for navigation purposes. The probe may include, by way of example only, a guidewire and / or a catheter. If probe 28 is implemented as a guidewire, a guidewire may be used to catheterize into the living subject over the guidewire once the guidewire is correctly positioned. For example, in some cases, a catheter may be too bulky and / or too soft to insert itself into the living subject without first using a guidewire.

[0049] Reference is now made to Figures 2 and 3. Figure 2 is a schematic diagram of a probe 28 for use in the systems 20a and 20b of Figures 1A or 1B. Figure 3 is a schematic diagram of elements of the probe 28 of Figure 2.

[0050] 2 and 3 includes a guidewire with various elements. In some embodiments, probe 28 may be implemented with different elements than those described below, while in some embodiments probe 28 may be provided with an integrated magnetic coil for navigation purposes in a deflectable probe. In some embodiments, probe 28 may be any suitable probe, such as a catheter or ENT instrument, with an integrated magnetic coil for navigation purposes.

[0051] The probe 28 is configured to be inserted into any suitable body portion of a living subject. The probe 28 includes a shaft 60 having a distal end 62.

[0052] The probe 28 includes a tube 64 containing loose powdered granules of ferrite. The tube 64 may have any suitable inner diameter. The inner diameter of the tube 64 is generally less than 150 microns, usually in the range of 100-750 microns. The tube 64 may have any suitable outer diameter, such as, but not limited to, less than 170 microns. The tube is formed of any suitable plastic or other suitable material that is thin enough and strong enough for the purpose, such as, but not limited to, polyimide. The tube 64 may be made of any suitable material, such as, but not limited to, a wide range of thermoplastics, such as polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP), or polyvinyl chloride (PVC). The powdered granules are not baked together to form a single solid mass, but in some embodiments may be held together using a binder such as an epoxy. The tube 64 is secured to the distal end 62 of the shaft 60. The tube 64 and powder granules are described in more detail with reference to FIGS.

[0053] The probe 28 includes a coil 66 disposed around the tube 64. The coil 66 may include any suitable insulated wire. In some embodiments, the coil 66 is wound with insulated copper wiring. The gauge of the wire may be any suitable gauge. In some embodiments, the wire is 60 gauge insulated copper wiring, which has an outer diameter of about 8 microns. The coil is covered by any suitable covering (not shown), for example, but not limited to, a plastic covering, such as a plastic tube, or a coating, such as an enamel or epoxy paint, a shrink sleeve, or a metal covering. The metal covering may also provide shielding from high frequency electromagnetic interference.

[0054] Probe 28 includes wires 68 connected to coil 66 to read signals generated across coil 66 by an externally applied magnetic field. In FIG. 2, wires 68 are shown spiraling down shaft 60. Wires 68 may be twisted pair conductors. Wires 68 may be disposed within a cable. Conductors of wires 68 may include any suitable conductor, such as, but not limited to, a copper alloy with 3% silver. Wires 68 connect coil 66 to a proximal end of probe 28, described in more detail below.

[0055] The externally applied magnetic field may be applied by a localization pad 24a or 24b (Figures 1a and 1b, respectively) having at least one magnetic field emitter 26a or 26b (Figures 1a and 1b, respectively) configured to transmit an alternating magnetic field to the area where the body part is located.

[0056] Processing circuitry 40 (FIGS. 1a and 1b) is coupled to electrical wires 68 (FIGS. 1a and 1b) via cable 19. Processing circuitry 40 is configured to receive signals from coil 66 and to calculate the position and orientation of distal end 62 in response to the received signals.

[0057] Additional elements of probe 28 will now be described. Figure 2 shows probe 28 in its assembled form, while Figure 3 shows the elements of the probe prior to assembly. Probe 28 includes a guidewire 70, which comprises the following: a solid rod core-wire 72, wires 68 arranged in a single cable, a formable elongate member 74 (Figure 3), a resilient elongate member 76, a shrink sleeve 78 (Figure 3), and a coil 66 around tube 64.

[0058] The solid rod core-wire 72 includes a distal end 80 and a surface channel 82 cut into the solid rod core-wire 72 for accommodating the electrical wire 68 therein (as shown in FIG. 2). In some embodiments, the surface channel 82 spirals around the core wire 72 away from the distal end 80 of the core wire 72 toward the proximal end of the probe 28. The solid rod core-wire 72 can be formed from any suitable material, such as, but not limited to, stainless steel, cobalt chrome, or nitinol. The solid rod core-wire 72 can have any suitable length. In some embodiments, the solid rod core-wire 72 has a length in the range of 1 to 3 meters, for example, about 2 meters. The solid rod core-wire 72 can have any suitable outer diameter. In some embodiments, the solid rod core-wire 72 can have an outer diameter in the range of 200 to 900 microns, for example, 300 microns. The distal end 80 of the solid rod core-wire 72 may be tapered (as shown in FIG. 3), for example, by grinding the distal end 80. The tapered portion of the solid rod core-wire 72 can be used to accommodate the proximal end of the elastic elongate member 76 thereon.

[0059] The proximal end of the elastic elongated member 76 is disposed over and connected to the tapered distal end 80 of the solid rod core-wire 72. The formable elongated member 74 is disposed on the elastic elongated member 76 such that the elastic elongated member 76 is disposed around the formable elongated member 74. The tube 64 is disposed distal to the elastic elongated member 76 and the formable elongated member 74. The tube 64 is connected to the elastic elongated member 76 at its distal end. The elastic elongated member 76 has an outer surface that includes a plurality of laser or machine cut grooves (or cut using any suitable method) disposed around the outer surface. The grooves make the elastic elongated member 76 more flexible. The elastic elongated member 76 may be formed from any suitable material. In some embodiments, the elastic elongated member 76 is formed from Nitinol. The elastic elongated member 76 may have any suitable length. In some embodiments, the elastic elongate member 76 has a length in the range of 1-30 cm, for example about 15 cm. The elastic elongate member 76 may have any suitable outer width. In some embodiments, the elastic elongate member 76 may have an outer width in the range of 275-900 microns, for example 325 microns. The elongate member 76 may have any suitable inner diameter, for example in the range of 150-800 microns, such as 200 microns, that is large enough to accommodate the moldable elongate member 74 therein.

[0060] The moldable elongate member 74 is connected to a distal end 80 of the core wire 72. The moldable elongate member 74 is configured to maintain its shape after being deformed by a physician who may purposefully deform the distal end of the probe 28 to navigate the probe 28 in one or more body parts. In some embodiments, the moldable elongate member 74 comprises a flattened wire helical spring. The moldable elongate member 74 may be formed from any suitable material. In some embodiments, the moldable elongate member 74 may be formed from stainless steel. The moldable elongate member 74 may have any suitable length. In some embodiments, the moldable elongate member 74 has a length in the range of 1-30 cm, for example about 15 cm. The moldable elongate member 74 is sized to fit within the hollow interior of the elastic elongate member 76. In some embodiments, the moldable elongate member 74 has an outer diameter in the range of 100-750 microns.

[0061] An electrical wire 68 extends from the coil 66 through the center of the moldable elongate member 74 and then is disposed around a surface channel 82 in the solid rod core-wire 72 until it reaches the proximal end of the probe 28 .

[0062] A shrink sleeve 78 is disposed over the solid rod core-wire 72. The shrink sleeve 78 helps retain the wires 68 in the surface channels 82. The shrink sleeve 78 may be formed from any suitable material, such as polyethylene terephthalate (PET) or a fluoropolymer. The shrink sleeve 78 typically covers the solid rod core-wire 72 for its entire length. In some embodiments, the shrink sleeve 78 may only partially cover the solid rod core-wire 72. In some embodiments, the shrink sleeve 78 may also cover the elastic elongate member 76. For simplicity, the shrink sleeve 78 is not shown in FIG. 2.

[0063] Reference is now made to Figures 4A-4D. Figure 4A is a flow chart 84 including steps in a method of manufacturing a magnetic coil 66 for use in the systems 20a and 20b of Figures 1A or 1B. Figures 4B-4D are schematic diagrams illustrating the manufacturing method described with reference to flow chart 84 of Figure 4A.

[0064] The method includes introducing loose powder granules 86 of ferrite (only some of which are labeled for simplicity) into tube 64 (block 88), as illustrated in FIG. 4B. Tube 64 may be made of any suitable material, which may be heat shrinkable, such as, but not limited to, a wide range of thermoplastics, such as polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP), or polyvinyl chloride (PVC). While powder granules 86 are being introduced into tube 64, the plastic tube has an outer diameter larger than the inner diameter of coil 66. For example, if the inner diameter of the coil is 180 microns, then the outer diameter of tube 64 in which powder granules 86 are disposed has an outer diameter of 250 microns and an inner diameter of about 180 microns. The outer diameter of tube 64 shrinks to 180 microns after heat shrinking, as described in more detail below. The preshrunk tube 64 may have any suitable outer diameter, depending on the inner diameter of the coil 66 and the heat shrink properties of the plastic tube. The preshrunk tube 64 may have any suitable outer diameter, for example, in the range of 150 to 1200 microns. The powdered granules 86 are disposed as loose granules within the tube 64 and are not bonded together to form a solid mass using heat and / or pressure after being placed in the tube 64. The powdered granules 86 may be bonded together using a binder such as a low viscosity epoxy after being placed in the tube 64, and the powdered granules may be carried into the tube 64 by capillary action after the tube 64 shrinks. Alternatively, it is contemplated that the tube 64 will not shrink once the epoxy has set, and therefore the epoxy may be carried into the tube 64 by capillary action before the tube 64 shrinks, and then the tube 64 shrinks while the epoxy is still liquid. The powder granules 86 may have any suitable size that is smaller than the inner diameter of the tube 64 in which the powder granules 86 are disposed.

[0065] The powdered granules 86 may be introduced into the tube 64 using any suitable method. For example, the powdered granules 86 may be introduced into the tube 64 through a funnel that matches an opening in the tube. The funnel is filled with the powdered granules 86 and vibrated up and down and / or side to side using any suitable vibration method, such as ultrasonic methods. The funnel may be coupled to the tube 64 and vibrated in coordination with the tube 64 to facilitate the introduction of the powdered granules 86 into the tube 64.

[0066] Additionally or alternatively, one or more magnets (electromagnets and / or permanent magnets) may be connected to the tube 64 to facilitate the introduction of the powdered granules 86 into the tube 64. For example, using a magnet connected to the bottom of the tube 64 and / or a ring-type magnet connected to the periphery of the tube 64. The magnets may allow the tube 64 to move (up and down and / or side to side), vibrate (up and down and / or side to side), and / or rotate.

[0067] The method includes heat shrinking (block 90) the tube 64 to have an outer diameter equal to the inner diameter of the coil 66, as illustrated in FIG. 4C. For example, the tube 64 shrinks from an outer diameter of 250 microns to 180 microns. The inner diameter of the shrink tube 64 is generally less than 150 microns, usually in the range of 100-750 microns. The heat applied in the heat shrink process is sufficient to shrink the tube 64, but not enough to cause the powder granules 86 to sinter and form a solid mass.

[0068] The method next includes disposing the coil 66 around the tube 64, typically by inserting the tube 64 into the coil 66 (block 92), as illustrated in FIG. 4D.

[0069] Reference is now made to Figures 5A-5E. Figure 5A is a flow chart 94 including steps in an alternative method of manufacturing a magnetic coil 66 for use in the systems 20a and 20b of Figures 1A or 1B. Figures 5B-5E are schematic diagrams illustrating the alternative method of manufacturing described with reference to the flow chart 94 of Figure 5A.

[0070] The method includes introducing (block 96) loose powdered granules of ferrite 86 (only some of which are labeled for simplicity) into tube 64. The process of block 96 will now be described in more detail with reference to the sub-processes of blocks 98-102.

[0071] The method includes suspending (block 98) powdered granules 86 in a liquid 106, such as, for example, but not limited to, an alcohol, such as isopropyl alcohol, or any other liquid having a sufficiently low viscosity and a sufficiently high evaporation rate, as illustrated in FIG. 5B. The suspending may be performed using any suitable method, such as, but not limited to, placing the powdered granules 86 with the liquid in a container on a vibration table (not shown), or using any other vibration method, such as using ultrasound. The volume percentage of the powdered granules in the suspension may be any suitable value, for example, in the range of 30-70%.

[0072] The method includes disposing an end of a tube 64 in a liquid 106 such that capillary action draws a portion of the liquid 106 containing the powdered granules 86 into the tube 64 (block 100), as illustrated in Figure 5C. The tube 64 has an outer diameter smaller than the inner diameter of the coil 66, for example in the range of 150-800 microns. The inner diameter of the tube 64 is generally smaller than 150 microns, and typically in the range of 100-750 microns. The tube 64 may be made of any suitable material, such as, but not limited to, a plastic, engineered ceramic, a carbon material, or a non-ferromagnetic metal.

[0073] The method includes evaporating the liquid 106 from the tube 64 (block 102), as illustrated in Figure 5D. The evaporation may be induced using any suitable method, such as using heating and / or blowing air over the tube 64. After evaporation, a bonding material, such as a low viscosity epoxy, may be carried by capillary action into the tube 68 to bond the powder granules 86 together.

[0074] The method typically involves disposing a coil 66 around a tube 64 by inserting the tube 64 into the coil 66 (block 104), as illustrated in FIG. 5E.

[0075] Various features of the invention that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0076] The embodiments described above are cited by way of example, and the present invention is not limited to what has been particularly shown and described in the above specification. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the above specification, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description.

[0077] [Embodiment] (1) a shaft having a distal end; a tube containing loose powder granules of ferrite, the tube being secured to the distal end of the shaft; a coil disposed around the tube; an electrical wire connected to the coil for reading a signal generated across the coil by an externally applied magnetic field; A probe device comprising: (2) The apparatus of embodiment 1, wherein the tube has an inner diameter of less than 150 μm (150 microns). (3) a solid rod core wire including a distal end and a surface channel for receiving said wire therein; a moldable elongate member connected to the distal end of the core wire and configured to retain a shape after deformation; a resilient elongate member disposed about the moldable elongate member, the tube being disposed distally relative to the resilient elongate member and the moldable elongate member; 2. The device of embodiment 1, further comprising a guidewire comprising: (4) The device of embodiment 3, wherein the surface channel spirals around the core wire away from the distal end of the core wire. (5) The device of claim 3, wherein the moldable elongate member comprises a flattened wire helical spring.

[0078] (6) The device of claim 3, wherein the elastic elongated member has an exterior surface including a plurality of cut grooves disposed about the periphery of the exterior surface. (7) The device of embodiment 3, wherein the guidewire includes a shrink sleeve disposed over the core wire that secures the electrical wire to the surface channel. (8) The device of embodiment 1, wherein the tube is formed from plastic. 9. The device of claim 8, wherein the plastic comprises polyimide. (10) A location tracking system, comprising: 1. A probe configured for insertion into a body part of a living subject, comprising: a shaft having a distal end; a tube containing loose powder granules of ferrite, the tube being secured to the distal end of the shaft; a coil disposed around the tube; wires connected to the coil for reading a signal generated across the coil by an applied magnetic field; A probe comprising: a location pad having at least one magnetic field emitter configured to transmit an alternating magnetic field to an area in which the body part is located; a processing circuit connected to the wire and configured to receive the signal from the coil and to calculate a position and orientation of the distal tip in response to the received signal; A location tracking system comprising:

[0079] (11) The system of claim 10, wherein the tube has an inner diameter of less than 150 μm (150 microns). (12) The probe, a solid rod core wire including a distal end and a surface channel for receiving said wire therein; a moldable elongate member connected to the distal end of the core wire and configured to retain a shape after deformation; a resilient elongate member disposed about the moldable elongate member, the tube being disposed distally relative to the resilient elongate member and the moldable elongate member; 11. The system of embodiment 10, comprising a guidewire comprising: (13) The system of embodiment 10, wherein the tube is formed from plastic. 14. The system of claim 13, wherein the plastic comprises polyimide. (15) introducing loose powdered granules of ferrite into the tube; disposing a coil around the tube; 13. A method for manufacturing a magnetic coil, comprising:

[0080] 16. The method of claim 15, wherein the tube has an inner diameter of less than 150 microns. 17. The method of claim 15, wherein the tube has an outer diameter greater than an inner diameter of the coil while the powdered granules are being introduced into the tube, the method further comprising heat shrinking the tube to have an outer diameter less than the inner diameter of the coil. (18) suspending the powdered granules in a liquid; disposing the tube in the liquid such that a portion of the liquid containing the powdered granules is drawn into the tube by capillary action; evaporating the liquid from the tube; and 16. The method of embodiment 15, further comprising: 19. The method of claim 18, wherein the liquid is alcohol. 20. The method of claim 15, wherein the tube is formed from plastic.

[0081] 21. The method of claim 20, wherein the plastic comprises a polyimide.

Claims

1. a shaft having a distal end; a tube comprising a thermoplastic material, the tube being secured to the distal end of the shaft, the tube having an inner diameter and an outer diameter, the inner diameter and the outer diameter being reduced by a heat shrink process such that the inner diameter is less than 150 microns; unbound powdered granules of ferrite contained within the inner diameter of the tube; a coil disposed about the outer diameter of the tube; an electrical wire connected to the coil for reading a signal generated across the coil by an externally applied magnetic field; A probe device comprising:

2. a solid rod core wire including a distal end and a surface channel for receiving said wire therein; a moldable elongate member connected to the distal end of the solid rod core wire and configured to retain a shape after deformation; a resilient elongate member disposed about the moldable elongate member, the tube being disposed distally relative to the resilient elongate member and the moldable elongate member; The apparatus of claim 1 , further comprising a guidewire comprising:

3. The device of claim 2 , wherein the surface channel spirals around the solid rod core wire away from the distal end of the solid rod core wire.

4. The device of claim 2 , wherein the moldable elongate member comprises a flattened wire helical spring.

5. The device of claim 2 , wherein the resilient elongate member has an exterior surface including a plurality of cut grooves disposed about a periphery of the exterior surface.

6. The device of claim 2 , wherein the guidewire comprises a shrink sleeve disposed over the solid rod core wire that secures the electrical wire to the surface channel.

7. The device of claim 1 , wherein the tube is formed from plastic.

8. The device of claim 7 , wherein the plastic comprises a polyimide.

9. 1. A location tracking system, comprising:

1. A probe configured for insertion into a body part of a living subject, comprising: a shaft having a distal end; a tube comprising a thermoplastic material, the tube being secured to the distal end of the shaft, the tube having an inner diameter and an outer diameter, the inner diameter and the outer diameter being reduced by a heat shrink process such that the inner diameter is less than 150 microns; unbound powdered granules of ferrite contained within the inner diameter of the tube; a coil disposed about the outer diameter of the tube; wires connected to the coil for reading a signal generated across the coil by an applied magnetic field; A probe comprising: a location pad having at least one magnetic field emitter configured to transmit an alternating magnetic field to an area where the body part is located; a processing circuit connected to the wire and configured to receive the signal from the coil and to calculate a position and orientation of the distal tip in response to the received signal; A location tracking system comprising:

10. The probe is a solid rod core wire including a distal end and a surface channel for receiving said wire therein; a moldable elongate member connected to the distal end of the solid rod core wire and configured to retain a shape after deformation; a resilient elongate member disposed about the moldable elongate member, the tube being disposed distally relative to the resilient elongate member and the moldable elongate member; 10. The system of claim 9, comprising a guidewire comprising:

11. The system of claim 9 , wherein the tube is formed from plastic.

12. The system of claim 11 , wherein the plastic comprises a polyimide.

Images