Very narrow probe with coil

Abstract

The present invention is entitled "Very Narrow Probe with Coil." In one embodiment, the present invention discloses a probe device comprising: a shaft having a distal end; a tube containing individual powder particles of ferrite, the tube being secured to the distal end of the shaft; a coil disposed around the tube; and wires connected to the coil for sensing a signal generated across the coil due to an externally applied magnetic field.

Description

Technical Field

[0001] The present invention relates to medical devices and, in particular, but not exclusively, to probes having navigation features. Background Art

[0002] A large number of medical operations involve placing probes such as guidewires and catheters in the patient's body. Position sensing systems have been developed to track such probes. Magnetic position sensing is a method known in the art. In magnetic position sensing, a magnetic field generator is usually placed at a known position 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, and the electrical signals are processed to determine the coordinate position of the distal end of the probe. These methods and systems are described in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT International Patent Publication WO 1996 / 005768, and in U.S. Patent Application Publication 2003 / 0120150 and 2004 / 0068178, the disclosures of which are all incorporated herein by reference.

[0003] Navigable guidewires typically have a diameter of about 1 mm or more, and this limits the parts of the body they can access, such as the distal end of the lungs and some blood vessels in the brain.

[0004] US Patent Publication No. 2016 / 0022154 to Warnking et al. describes a system for detecting blood pressure in a blood vessel, the system including 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 of a fluid external to the guidewire, such that the resonant circuit has a resonant frequency that changes according to pressure changes of 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 expansion lumen. The inflatable balloon can be attached to the distal end of the catheter body. The balloon has an inner surface that at least partially defines an internal volume. The balloon is configured so that the internal volume can be in fluid communication with the expansion 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 through the balloon. 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 2019 / 0022363 to Grayzel et al. describes a medical guide element for use with a dilator to be inserted into an organ or body structure (such as a kidney) of a patient. 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. The change in diameter is abrupt, thereby providing a discrete step transition at a point along the filament, which presents a proximal-facing surface on the distal segment. When the proximal segment of the guide element is fully inserted into a dilator having a distal tip suitable for insertion into the patient's body, the dilator distal tip firmly abuts the proximal-facing end surface of the distal segment. The relative size of the dilator tip and the discrete step-like transition of the guide element provide complete shielding or over-shielding of the dilator tip, thereby facilitating the dilator tip to pass through the puncture hole and enter the orifice along the tissue track. Summary of the Invention

[0007] According to an embodiment of the present disclosure, a probe device is provided, comprising: a shaft having a distal end; a tube containing individual powder particles of ferrite, the tube being fixed to the distal end of the shaft; a coil disposed around the tube; and a wire connected to the coil for reading a signal generated across the coil due to an externally applied magnetic field.

[0008] According to further embodiments of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0009] Still further according to an embodiment of the present invention, the device includes a guide wire, the guide wire comprising: a solid rod core wire, the solid rod core wire comprising a distal end and a surface channel for receiving the wire therein; a formable slender member, the formable slender member being connected to the distal end of the core wire and being configured to maintain a shape after deformation; and a resilient slender member disposed around the formable slender member, wherein the tube is disposed distally of the resilient slender member and the formable slender member.

[0010] Additionally, 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] Furthermore, according to an embodiment of the present disclosure, the formable elongated member comprises a flat wire coil spring.

[0012] In further accordance with an embodiment of the present disclosure, the resilient elongated member includes an outer surface including a plurality of cut grooves disposed therearound.

[0013] Still further in accordance with an embodiment of the present invention, the guidewire includes a shrink sleeve disposed over the core wire, thereby retaining the wire in the surface channel.

[0014] Additionally, according to embodiments of the present disclosure, the tube is formed of plastic.

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

[0016] According to another embodiment of the present disclosure, a position tracking system is also provided, which includes: a probe, which is configured to be inserted into a body part of a living subject and includes an axis having a distal end; a tube, which contains separate powder particles of ferrite and is fixed to the distal end of the axis; a coil, which is arranged around the tube; and a wire, which is connected to the coil so as to read out a signal generated across the coil due to an applied magnetic field; a position pad, which has at least one magnetic field radiator, which is configured to transmit an alternating magnetic field to an area where the body part is located; and a processing circuit, which is coupled to the wire and configured to receive the signal from the coil and calculate the position and orientation of the distal end in response to the received signal.

[0017] According to further embodiments of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0018] Still further according to an embodiment of the present invention, the probe includes a guide wire, which includes: a solid core wire, the solid core wire including a distal end and a surface channel for receiving the wire therein; a formable slender member, the formable slender member is connected to the distal end of the core wire and is configured to maintain a shape after deformation; and an elastic slender member, the elastic slender member is arranged around the formable slender member, wherein the tube is arranged distally of the elastic slender member and the formable slender member.

[0019] Additionally, according to embodiments of the present disclosure, the tube is formed of plastic.

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

[0021] According to yet another embodiment of the present disclosure, there is also provided a method for producing a magnetic coil, the method comprising introducing individual powder particles of ferrite into a tube, and disposing a coil around the tube.

[0022] According to further embodiments of the present disclosure, the tube has an inner diameter of less than 150 microns.

[0023] Still further in accordance with an embodiment of the present invention, upon introducing the powder particles into the tube, the tube has an outer diameter greater than an inner diameter of the coil, the method further comprising heat shrinking the tube to have an outer diameter smaller than the inner diameter of the coil.

[0024] Additionally, according to an embodiment of the present invention, the method includes suspending the powder particles in a liquid, placing the tube in the liquid such that capillary action draws some of the liquid with the powder particles into the tube, and causing the liquid to evaporate from the tube.

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

[0026] According to further embodiments of the present disclosure, the tube is formed of plastic.

[0027] Still further in accordance with an embodiment of the present invention, 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, in which:

[0029] Figure 1A and Figure 1B is a schematic diagram of a probe-based cerebral blood vessel position tracking system according to an embodiment of the present invention;

[0030] Figure 2 is Figure 1A or Figure 1B Schematic diagram of the probe used in the system;

[0031] Figure 3 yes Figure 2 A schematic diagram of the components of the probe;

[0032] Figure 4A Including manufacturing Figure 1A or Figure 1B A flow chart of the steps in a method of using a magnetic coil in a system;

[0033] Figures 4B to 4D Reference Figure 4A A schematic diagram of a manufacturing method described in a flowchart;

[0034] Figure 5A Including manufacturing Figure 1A or Figure 1B A flowchart of the steps in the method of using an alternative magnetic coil in a system; and

[0035] Figures 5B to 5E Reference Figure 5A Flowchart describing a schematic diagram of an alternative fabrication method. DETAILED DESCRIPTION

[0036] Overview

[0037] As previously mentioned, navigable probes such as guidewires typically have a diameter of about 1 mm or more, and this limits the parts of the body they can access, such as the distal end of the lungs and some blood vessels in the brain.

[0038] Making probes with smaller diameters equal to or less than 0.9 mm (such as about 300 microns or less) is not simply a miniaturization task achieved by making the various elements of the probe smaller. One such challenge is producing a sufficiently small magnetic core for the probe's navigation coil.

[0039] For example, a magnetic antenna may use a magnetic core made of a ferromagnetic material or ferrimagnetic material (such as iron or nickel-zinc ferrite or magnesium-zinc ferrite) to increase the magnetic permeability. The magnetic core can increase the sensitivity of the antenna by up to several thousand times by increasing the magnetic field due to its higher magnetic permeability. Therefore, the coils used in navigable probes typically include coils with magnetic cores. Solid magnetic cores can be constructed by any suitable method, including using a binder and / or very high temperatures (sintering) to combine magnetic core powders to form a solid block. However, the above-mentioned production methods are generally not suitable for preparing solid magnetic cores that are small enough to be inserted into coils with an inner diameter of about 500 microns or less.

[0040] Embodiments of the present invention provide a probe comprising a shaft having a distal end and a tube fixed to the distal end of the shaft. The tube contains individual powder particles of ferrite, and a coil is placed around the tube, for example, by inserting the tube into the coil. The coil is then covered with a covering that holds the coil in place and acts as a biocompatible covering. The wire used in the coil may have any suitable specification, such as, but not limited to, 60 gauge with a diameter of approximately 8 microns. The powder particles are held in place by the tube. The powder particles are not sintered to form a single block, but they can be bonded together using a binder material (such as epoxy). The tube can be formed of any suitable material, such as a wide range of thermoplastics, such as polyimide, polyamide, polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP) or polyvinyl chloride (PVC), or other materials, such as engineering ceramics, carbon materials or non-ferromagnetic metals. The tube provides a controlled outer diameter surface on which the coil slides.

[0041] Wires are connected to the coil to read the signal generated across the coil due to an externally applied magnetic field. The signal provided by the coil is used to calculate the position and orientation of the distal tip of the probe. The powder particles increase the magnetic permeability of the coil and increase the amplitude of the signal provided by the coil.

[0042] Because the powder particles may have a size of about 40 microns, it is difficult to place the powder particles into the tube, which in some embodiments may have an inner diameter as low as 100. In some cases, the powder particles have a size that is approximately the radius of the tube. The present invention, in its embodiments, provides a novel method for introducing powder particles into the tube.

[0043] As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows the component or collection of elements to achieve its intended purpose as described herein. More specifically, "about" or "approximately" can refer to a range of ±20% of the value of the recited value, for example, "about 90%" can refer to a range of values ​​from 71% to 99%.

[0044] In some embodiments, the powder particles are placed in a heat-shrinkable tube having an outer diameter greater than the inner diameter of the coil. For example, the powder particles can be placed in a tube having an inner diameter of about 180 microns and an outer diameter of about 250 microns. Compared to placing the powder particles in a tube having an inner diameter of 150 microns or less, placing the powder particles in a tube having an inner diameter of about 180 microns is significantly easier. Heat is then applied to the tube to cause it to heat shrink until the outer diameter equals the inner diameter of the coil. The heat-shrinkable tube is then inserted into the coil. The tube can be formed of 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).

[0045] In some embodiments, the powder particles are suspended in a liquid (such as an alcohol, for example, isopropyl alcohol) using, for example, a vibrating table. The end of a tube having an outer diameter less than the inner diameter of the coil is then placed in the liquid, and the powder particle suspension is drawn into the tube by capillary action. The evaporation process is then started to evaporate the liquid in the tube, thereby leaving the powder particles in the tube. The powder particle-filled tube is inserted into the coil. The tube can be formed of 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).

[0046] System Description

[0047] Documents incorporated herein by reference are to be considered an integral part of this application, except that, to the extent any term is defined in these incorporated documents in a manner that contradicts a definition explicitly or implicitly set forth in this specification, only the definition in this specification shall prevail.

[0048] Figure 1A and Figure 1B is a schematic illustration of probe-based cerebral blood vessel position tracking systems 20a and 20b according to an embodiment of the present invention.

[0049] In some embodiments, before performing a medical procedure, a CT image of patient 32 is acquired. The CT image is stored in memory 42 for subsequent retrieval by processing circuit 40. Processing circuit 40 uses the image to present, for example, an image 59 of a portion of the brain on display 56. In another embodiment, during the disclosed medical procedure, tracking systems 20a and 20b register the position and orientation of the distal end of probe 28 within the patient's brain, where the reference frame of the patient's 32 brain image (assumed herein by way of example) includes a real-time fluoroscopic image. The position and orientation of the distal end of probe 28 is tracked using a magnetic tracking subsystem 23 that tracks the position and orientation coordinates of a magnetic sensor mounted at the distal end of probe 28. Magnetic tracking subsystem 23 can form part of tracking subsystem 33. Using magnetic position and orientation tracking subsystem 23, physician 54 advances the distal end of probe 28 through the vascular system.

[0050] exist Figure 1A In the illustrated system 20a, the location pad 24a included in the magnetic tracking subsystem 23 is implemented as a collar around the neck of patient 32. By placing the location pad 24a around the neck, it is configured to automatically compensate for patient head movement. The location pad 24a includes a magnetic field radiator 26a, which is fixed in position relative to the head of patient 32 and transmits a sinusoidal alternating magnetic field into the region 30 where the head of patient 32 is located. The console 50 electrically drives the radiator 26a via a cable 25. In one embodiment, further compensation for head movement is provided by attaching a reference sensor 21 to the patient's forehead. The console 50 is configured to receive signals from the reference sensor 21 via a cable 27. A position tracking system including a neck collar location pad is described in U.S. patent application Ser. No. 16 / 248,393, entitled "Position Sensor on BrainClot Sheath and Location Pad Collar," filed on January 15, 2019, which is assigned to the assignee of the present patent application and whose disclosure is incorporated herein by reference.

[0051] Physician 54, operating system 20a, holds controller handle 29, which is connected to the proximal end of probe 28. Controller handle 29 allows the physician to advance and navigate probe 28 in the brain, for example, through entry point 22 at the femoral artery of patient 32. As described above and below, physician 54 uses position and orientation signals from a magnetic sensor mounted at the distal end of probe 28 to navigate the distal end of probe 28. Console 50 receives the magnetic sensor signals via cable 19, which is connected to probe 28 via handle 29.

[0052] The elements of the system 20a including the radiator 26a are controlled by a processing circuit 40 that includes a processing unit in communication with one or more memories (e.g., memory 42). The processing circuit 40 can be mounted in a console 50 that includes operating controls 58 that typically include a keypad and / or a pointing device, such as a mouse or trackball. A physician 54 can interact with the processing circuit 40 using the operating controls on the handle 29 when performing registration of the system 20a. During the registration process, an image 59 of the brain portion is presented on the display 56. Following the registration process, the physician 54 uses the operating controls to advance the distal end of the probe 28 to one or more desired locations in the brain.

[0053] The processing circuit 40 uses software stored in the memory 42 to operate the system 20a. In implementation, some or all of the functions of the processing circuit 40 can be combined in a single physical component, or alternatively, multiple physical components can be used to implement it. These physical components may include hard-wired or programmable devices, or a combination of the two. In some embodiments, at least some of the functions of the processing circuit 40 can be implemented by a programmable processor under the control of appropriate software. The software can be downloaded to the device in electronic form over a network, for example. Alternatively or in addition, the software can be stored in a tangible, non-transitory computer-readable storage medium, such as an optical, magnetic, or electronic memory.

[0054] Figure 1B The system 20b shown in FIG has a different magnetic position pad design, namely position pad 24b. As seen, position pad 24b is secured to the bed and irradiator 26b is resting horizontally around the patient's headrest. In this example, system 20b lacks reference sensor 21, so the patient's head must be harnessed to prevent head movement. The other components of system 20b are generally the same as those of system 20a. A position tracking system using a position pad similar to position pad 24b is described in U.S. patent application 15 / 674,380, entitled "ENT Image Registration," filed on August 10, 2017, which is assigned to the assignee of the present patent application and the disclosure of which is incorporated herein by reference.

[0055] Figure 1A and Figure 1B The systems 20a and 20b shown in FIG. 2 are chosen solely for conceptual clarity. Other system elements may be included, such as additional controls on the handle 29 for controlling additional tools such as for drug delivery.

[0056] Tracking the position and orientation of magnetic position sensors in organs of the body using techniques similar to those employed by systems 20a and 20b Magnetic tracking systems are manufactured by Biosense-Webster (Irvine, California). Generally, position sensing using current distribution measurements and / or external magnetic fields is described in detail in U.S. Patents 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, PCT Patent Publication No. WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455A1, 2003 / 0120150A1, and 2004 / 0068178A1, the disclosures of which are incorporated herein by reference in their entirety.

[0057] Above description has described the navigation probe in cerebral blood vessels.System 20a and 20b can be suitably adapted to the navigation probe in the suitable body part (such as sinus cavity, heart or kidney) in the living subject.Probe 28 can be implemented as any suitable probe with the magnetic coil for navigation purposes.Only by way of example, probe can comprise guide wire and / or conduit.If probe 28 is implemented as guide wire, then once guide wire is correctly positioned, guide wire just can be used for entering the living subject on the guide wire top as conduit.For example, in some cases, conduit may be too large and / or too soft and can't voluntarily insert in the living subject body when not first using guide wire.

[0058] Now refer to Figure 2 and Figure 3 . Figure 2 is used for Figure 1A or Figure 1B Schematic diagram of probe 28 of systems 20a and 20b. Figure 3 yes Figure 2 Schematic diagram of the components of the probe 28.

[0059] refer to Figure 2 and Figure 3 The probe 28 described includes a guidewire having various elements. In some embodiments, the probe 28 can be implemented with elements different from those described below, while still providing a deflectable probe with an integrated magnetic coil for navigation purposes. In some embodiments, the probe 28 can be any suitable probe with an integrated magnetic coil for navigation purposes, such as a catheter or ENT tool.

[0060] Probe 28 is configured to be inserted into any suitable body part of a living subject.Probe 28 includes a shaft 60 having a distal end 62.

[0061] The probe 28 includes a tube 64 containing individual powder particles of ferrite. The tube 64 can have any suitable inner diameter. The inner diameter of the tube 64 is typically less than 150 microns and is typically in the range of 100 microns to 750 microns. The tube 64 can 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 can 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 powder particles are not sintered together to form a single solid block, but in some embodiments, can be held together by a binder (such as an epoxy resin). The tube 64 is fixed to the distal end 62 of the shaft 60. Reference Figure 4A -D and Figure 5A -E describes the tube 64 and the powder particles in more detail.

[0062] The probe 28 includes a coil 66 disposed around the tube 64. The coil 66 may comprise any suitable insulated wire. In some embodiments, the coil 66 is wound from insulated copper wire. The wire may be of any suitable specification. In some embodiments, the wire is a 60 gauge insulated copper wire having an outer diameter of approximately 8 microns. The coil may be covered with any suitable covering (not shown), such as, but not limited to, a plastic covering such as a plastic tube, or covered with a coating such as enamel or epoxy paint, a shrink sleeve, or a metal cover. The metal cover may also provide shielding to prevent high frequency electromagnetic interference.

[0063] The probe 28 includes wires 68 connected to the coil 66 for reading the signal generated across the coil 66 due to the externally applied magnetic field. Figure 2 , wire 68 is shown coiled down shaft 60. Wire 68 may be a twisted pair of conductors. Wire 68 may be disposed in a cable. The conductor of wire 68 may include any suitable conductor, such as, but not limited to, a copper alloy with 3% silver. Wire 68 connects coil 66 to the proximal end of probe 28, as described in more detail below.

[0064] The externally applied magnetic field can be generated by the position pad 24a or 24b ( Figure 1A and Figure 1B , respectively) are applied, the position pad has at least one magnetic field radiator 26a or 26b ( Figure 1A and Figure 1B , respectively), the magnetic field radiator is configured to transmit an alternating magnetic field into an area where the body part is located.

[0065] Processing circuit 40 ( Figure 1A and Figure 1B ) via cable 19( Figure 1A and Figure 1B ) is coupled to wire 68. Processing circuit 40 is configured to receive signals from coil 66 and calculate the position and orientation of distal end 62 in response to the received signals.

[0066] Additional elements of the probe 28 will now be described. Figure 2 The probe 28 is shown in its assembled form, and Figure 3 The probe 28 includes a guide wire 70 comprising a solid rod core wire 72, an electric wire 68 arranged in a single cable, a shapeable elongated member 74 ( Figure 3 )、Elastic elongated member 76、Shrink sleeve 78( Figure 3 ); and a coil 66 surrounding the tube 64.

[0067] The solid core wire 72 includes a distal end 80 and a surface channel 82 cut into the solid core wire 72 for receiving the wire 68 (e.g., Figure 2 ). In some embodiments, the surface channel 82 spirals around the core wire 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 of any suitable material, such as, but not limited to, stainless steel, cobalt chromium, or nickel titanium alloy. 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 meter 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 microns to 900 microns, for example, 300 microns. The distal end 80 of the solid rod core wire 72 can be tapered (such as by grinding the distal end 80), for example. Figure 3 ). The tapered portion of the solid rod core wire 72 may be used to receive the proximal end of the resilient elongated member 76 thereon.

[0068] The proximal end of the elastic elongated member 76 is disposed above and connected to the tapered distal end 80 of the solid rod core wire 72. The formable elongated member 74 is disposed in the elastic elongated member 76 so that the elastic elongated member 76 is disposed around the formable elongated member 74. The tube 64 is disposed distally of the elastic elongated member 76 and the formable elongated member 74. The tube 64 is connected to the elastic elongated member 76 at the distal end of the elastic elongated member 76. The elastic elongated member 76 includes an outer surface that includes a plurality of laser or mechanically 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 can be formed from any suitable material. In some embodiments, the elastic elongated member 76 is formed from nitinol. The elastic elongated member 76 can have any suitable length. In some embodiments, the elastic elongated member 76 has a length ranging from 1 cm to 30 cm, for example, approximately 15 cm. The elastic elongated member 76 can have any suitable outer width. In some embodiments, the elastic elongated member 76 can have an outer width in the range of 275 microns to 900 microns, for example 325 microns. The elongated member 76 can have any suitable inner diameter, for example in the range of 150 microns to 800 microns (such as 200 microns), and be large enough to accommodate the formable elongated member 74 therein.

[0069] The formable elongated member 74 is connected to the distal end 80 of the core wire 72. The formable elongated member 74 is configured to maintain its shape after being deformed by a physician who may intentionally deform the distal end of the probe 28 in order to navigate the probe 28 in one or more body parts. In some embodiments, the formable elongated member 74 comprises a flat wire coil spring. The formable elongated member 74 may be formed from any suitable material. In some embodiments, the formable elongated member 74 may be formed from stainless steel. The formable elongated member 74 may be any suitable length. In some embodiments, the formable elongated member 74 has a length in the range of 1 cm to 30 cm, for example, about 15 cm. The formable elongated member 74 is sized to fit within the hollow portion of the elastic elongated member 76. In some embodiments, the formable elongated member 74 has an outer diameter in the range of 100 microns to 750 microns.

[0070] The wires 68 extending from the coil 66 are disposed through the center of the formable elongate member 74 and then around the surface passage 82 of the solid core wire 72 until reaching the proximal end of the probe 28 .

[0071] A shrink sleeve 78 is disposed over the solid core wire 72. The shrink sleeve 78 helps to retain the wire 68 in the surface channel 82. The shrink sleeve 78 can be formed from any suitable material, such as polyethylene terephthalate (PET) or a fluoropolymer. The shrink sleeve 78 typically covers the solid core wire 72 over its entire length. In some embodiments, the shrink sleeve 78 may only partially cover the solid core wire 72. In some embodiments, the shrink sleeve 78 may also cover the resilient elongated member 76. For simplicity, Figure 2 The shrink sleeve 78 is not shown.

[0072] Now see Figures 4A to 4D . Figure 4A Including manufacturing Figure 1A or Figure 1B Flowchart 84 of the steps in a method of using the magnetic coil 66 in the systems 20a and 20b. Figures 4B to 4D Reference Figure 4A The flowchart 84 is a schematic diagram of a description of the manufacturing method.

[0073] The manufacturing method includes introducing (block 88) individual powder particles 86 of ferrite (only some are labeled for simplicity) into the tube 64, as shown in FIG. Figure 4B As shown. Tube 64 can be made of any suitable heat-shrinkable 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). When powder particles 86 are introduced into tube 64, the outer diameter of the plastic tube is larger than the inner diameter of coil 66. For example, if the inner diameter of the coil is 180 microns, the outer diameter of tube 64 into which powder particles 86 are placed has an outer diameter of 250 microns and an inner diameter of approximately 180 microns. The outer diameter of tube 64 shrinks to 180 microns after heat shrinking, as described in more detail below. Depending on the inner diameter of coil 66 and the heat shrinkage properties of the plastic tube, pre-shrink tube 64 can have any suitable outer diameter. Pre-shrink tube 64 can have any suitable outer diameter, for example, in the range of 150 to 1200 microns. Powder particles 86 are placed in tube 64 as individual particles and are not bonded together to form a solid block using heat and / or pressure after placement in tube 64. The powder particles 86 can be bonded together after being placed in the tube 64 using a binder, such as a low viscosity epoxy, which can wick into the tube 64 by capillary action after or before the tube 64 shrinks and then shrink the tube 64 while the epoxy is still liquid, as it cannot shrink the tube 64 once the epoxy cures. The powder particles 86 can have any suitable size that is smaller than the inner diameter of the tube 64 into which the powder particles 86 are placed.

[0074] Any suitable method can be used to introduce the powder particles 86 into the tube 64. For example, the powder particles 86 can be introduced into the tube 64 using a funnel aligned with the tube opening. The funnel is filled with the powder particles 86 and vibrated up and down and / or side to side using any suitable vibration method, such as an ultrasonic method. The funnel can be connected to the tube 64 and vibrated in unison with the tube 64 to facilitate the introduction of the powder particles 86 into the tube 64.

[0075] Additionally or alternatively, one or more magnets (electromagnets and / or permanent magnets) may be attached to the tube 64 to facilitate the introduction of the powder particles 86 into the tube 64. For example, a magnetic member attached to the bottom of the tube 64 and / or a ring-shaped magnetic member attached around the tube 64 may be used. The magnets may allow for movement (upward and downward, and / or sideways), vibration (upward and downward, and / or sideways), and / or rotation of the tube 64.

[0076] The method includes heat shrinking the tube 64 (block 90) to have an outer diameter equal to the inner diameter of the coil 66, as shown. Figure 4C As shown. For example, the tube 64 is shrunk from an outer diameter of 250 microns to 180 microns. The inner diameter of the shrunk tube 64 is typically less than 150 microns and is typically in the range of 100 to 750 microns. The heat applied during the heat shrinking process is sufficient to shrink the tube 64, but not enough to cause the powder particles 86 to form a solid block through sintering.

[0077] The method then includes disposing the coil 66 around the tube 64, typically by inserting (block 92) the tube 64 into the coil 66, as in Figure 4D shown.

[0078] Now see Figure 5A -E, Figure 5A Including manufacturing Figure 1A or Figure 1B Flowchart 94 of the steps in an alternative method of using the magnetic coil 66 in systems 20a and 20b. Figures 5B to 5E Reference Figure 5A Flowchart 94 is a schematic diagram of an alternative manufacturing method.

[0079] The manufacturing method includes introducing (box 96) individual powder particles 86 of ferrite (only some are labeled for simplicity) into the tube 64. The steps of box 96 are described in more detail with reference to the sub-steps of boxes 98 to 102.

[0080] The method includes suspending (block 98) powder particles 86 in a liquid 106, such as an alcohol (e.g., but not limited to, isopropyl alcohol), or any other liquid having a sufficiently low viscosity and a sufficiently high evaporation rate, such as Figure 5BAs shown. Suspension can be performed using any suitable method, such as, but not limited to, placing the powder particles 86 with the liquid in a container on a vibrating table (not shown), or by using any other vibration method (such as ultrasound). The volume percentage of the powder particles in the suspension can be any suitable value, for example, in the range of 30-70%.

[0081] The method includes placing (block 100) the end of the tube 64 in a liquid 106 such that capillary action draws some of the liquid 106 with the powder particles 86 into the tube 64, as shown. Figure 5C As shown. The outer diameter of tube 64 is smaller than the inner diameter of coil 66, for example, ranging from 150 microns to 800 microns. The inner diameter of tube 64 is typically less than 150 microns and typically ranges from 100 microns to 750 microns. Tube 64 can be made of any suitable material, such as, but not limited to, plastic, engineered ceramics, carbon materials, or non-ferromagnetic metals.

[0082] The method includes causing liquid 106 to evaporate from tube 64 (block 102), as Figure 5D Any suitable method, such as using heat and / or blowing air over the tube 64, may be used to induce evaporation. After evaporation, a binder, such as a low viscosity epoxy resin, may be wicked into the tube 68 by capillary action to bond the powder particles 86 together.

[0083] The method includes disposing the coil 66 around the tube 64, typically by inserting (block 104) the tube 64 into the coil 66, as in Figure 5E shown.

[0084] For clarity, various features of the invention described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for simplicity, various features of the invention are described in the context of a single embodiment and may also be provided separately or in any suitable subcombination.

[0085] The above embodiments are cited by way of example, and the present invention is not limited by what has been specifically shown and described hereinabove. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description and which are not disclosed in the prior art.

Claims

1. A probe device comprising: a shaft having a distal end; a tube comprising unbound and uncompressed powder particles of ferrite, the tube being secured to the distal end of the shaft; a coil disposed around the tube; as well as An electrical wire is connected to the coil for sensing a signal generated across the coil due to an externally applied magnetic field.

2. The device according to claim 1, characterized in that The tube has an inner diameter of less than 150 microns.

3. The device according to claim 1, characterized in that The device further comprises a guide wire comprising: a solid core wire including a distal end and a surface channel for receiving the wire therein; a shapeable elongate member connected to the distal end of the core wire and configured to retain a shape after deformation; and A resilient elongated member is disposed about the shapeable elongated member, wherein the tube is disposed distally of the resilient elongated member and the shapeable elongated member.

4. The device according to claim 3, characterized in that The surface channel spirals around the core wire away from the distal end of the core wire.

5. The device according to claim 3, characterized in that The formable elongated member comprises a flat wire coil spring.

6. The device according to claim 3, characterized in that The resilient elongated member includes an outer surface comprising a plurality of cut grooves disposed therearound.

7. The device according to claim 3, characterized in that The guidewire includes a shrink sleeve disposed over the core wire, thereby retaining the wire in the surface channel.

8. The device according to claim 1, characterized in that The tube is formed from plastic.

9. The device according to claim 8, characterized in that The plastic comprises polyimide.

10. A location tracking system comprising: A probe configured to be inserted into a body part of a living subject and comprising: a shaft having a distal end; a tube comprising unbound and uncompressed powder particles 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 for sensing a signal generated by an applied magnetic field across the coil; a location mat having at least one magnetic field radiator configured to transmit an alternating magnetic field into the region where the body part is located; and A processing circuit is coupled to the electrical wire and is configured to: receive the signal from the coil; and calculate the position and orientation of the distal end in response to the received signal.

11. The system according to claim 10, wherein: The tube has an inner diameter of less than 150 microns.

12. The system according to claim 10, wherein: The probe includes a guide wire, and the guide wire includes: a solid core wire including a distal end and a surface channel for receiving the wire therein; a shapeable elongate member connected to the distal end of the core wire and configured to retain a shape after deformation; and A resilient elongate member is disposed about the shapeable elongate member, wherein the tube is disposed distally of the resilient elongate member and the shapeable elongate member.

13. The system according to claim 10, wherein: The tube is formed from plastic.

14. The system according to claim 13, wherein: The plastic comprises polyimide.

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