Medical equipment

Abstract

A medical device formed in an elongated shape and having a distal end side inserted into a body for use includes a magnetizing member having a magnetized portion formed at a portion of the distal end side, the magnetized portion including magnetized martensitic stainless steel.

Description

Technical Field

[0001] The present disclosure relates to medical devices. Background Art

[0002] In order to perform minimally invasive treatment or inspection in the lumens of biological bodies such as the circulatory system and the digestive system, medical devices such as guide wires and catheters are used. In such medical devices, it is desirable to be able to check the position of the medical device inserted into the body. For example, Patent Document 1 discloses a structure in which a plurality of magnet pieces are arranged on a medical tube to check the position of the medical tube. In addition, Patent Document 2 discloses a structure in which a source coil as a magnetic field generating element is arranged at the insertion portion of the medical device inserted into the body and the magnetic field generated by the source coil is detected, thereby detecting the lumen organ into which the insertion portion is inserted. In addition, Patent Document 3 discloses a structure in which a magnetic mechanism is provided in the medical device, and a magnetic mechanism (magnetic region) of a material such as a ferromagnetic body magnetized by a magnetic field applied from the outside, a paramagnetic body, etc. is detected to detect the position of the medical device. In addition, Patent Document 4 discloses a structure in which a magnet is buried at the front end of a medical device such as a guide wire.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-99713

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-280591

[0007] Patent Document 3: Japanese Patent Application No. 2019-520129

[0008] Patent Document 4: Japanese Patent Application Publication No. 2013-103075 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, the structure of configuring a magnet in a medical device as in Patent Document 1 and Patent Document 4, or the structure of configuring a coil as an electromagnet in a medical device as in Patent Document 2, is difficult to adopt because the properties of the medical device such as flexibility are affected, or the structure of the medical device is complicated and enlarged. In addition, in the structure of providing a magnetic region magnetized by a magnetic field applied from the outside as in Patent Document 3, it is difficult to adopt because a device for applying a magnetic field from the outside is required when detecting the position of the medical device, which causes the overall structure of the position detection system to be complicated and enlarged. Therefore, a technology for detecting the position of a medical device while suppressing the influence on the performance of the medical device and suppressing the complexity and enlargement of the device is desired.

[0011] Solutions to Solve Problems

[0012] The present disclosure can be implemented as the following aspects.

[0013] (1) According to one aspect of the present disclosure, there is provided a medical device formed in an elongated shape and having a distal end side inserted into a body for use. The medical device includes a magnetizing member having a magnetized portion formed at a portion of the distal end side, the magnetized portion comprising magnetized martensitic stainless steel.

[0014] The medical device according to this scheme is provided with a magnetized component having a magnetized portion formed on a part of the front end side, and the magnetized portion includes magnetized martensitic stainless steel, so that the magnetized portion that can be used to detect the position of the medical device can be set by magnetizing the magnetized component including the martensitic stainless steel. Therefore, unlike the case where a magnetized component such as a permanent magnet is further installed in the medical device, the complexity and enlargement of the structure of the medical device can be suppressed, and the position of the front end of the medical device can be detected. In addition, unlike the case where a magnetized component such as a permanent magnet is further installed in the medical device, the strength reduction of the medical device caused by the formation of the magnetized portion can be suppressed, and the risk of the magnetized portion being peeled off from the medical device can be suppressed. In addition, since the magnetized portion including the magnetized martensitic stainless steel is provided, it is not necessary to apply an external magnetic field when detecting the position of the medical device. Therefore, the complexity and enlargement of the structure of the medical device and the system including the position detection device of the medical device can be suppressed.

[0015] (2) In the medical device of the above scheme, the magnetized component is preferably a core shaft, and the magnetized portion is provided at the front end of the core shaft. If such a structure is adopted, the magnetized portion is formed by magnetizing the core shaft provided by the medical device, and the position of the front end of the core shaft can be detected.

[0016] (3) In the medical device of the above scheme, it is preferred that a high coercivity layer is further provided, which is formed in a manner covering at least a portion of the surface of the magnetized component and contains a material having an inherent coercivity higher than that of martensitic stainless steel, and the magnetized portion magnetizes the high coercivity layer together with the magnetized component. If such a structure is provided, since the magnetized portion magnetizes the high coercivity layer together with the magnetized component, the magnetic field intensity of the magnetized portion can be increased compared to a case where the high coercivity layer is not provided. As a result, the accuracy of detecting the position of the medical device using the magnetized portion can be improved.

[0017] (4) In the medical device of the above scheme, it is preferred that the magnetized portion is provided in plurality at intervals in the axial direction of the medical device. If such a structure is used, the three-dimensional movement of the front end of the medical device can be grasped with greater accuracy by detecting the positions of the plurality of magnetized portions separately.

[0018] (5) In the medical device of the above scheme, it is preferred that the magnetic force lines of at least two of the plurality of magnetized portions extend in mutually different directions. If such a structure is adopted, the accuracy of grasping the three-dimensional movement of the front end portion of the medical device can be further improved by detecting the extension directions of the magnetic force lines of the plurality of magnetized portions differently.

[0019] (6) In the medical device of the above scheme, it is preferred that a bending portion formed by bending the medical device in a specified direction is provided at the front end of the medical device, and a first magnetization portion as one of the plurality of magnetization portions is provided at a front end side relative to the bending portion, and a second magnetization portion as another of the plurality of magnetization portions is provided at a base end side relative to the bending portion. If such a structure is provided, the accuracy of grasping the three-dimensional movement of the front end of the medical device can be improved by distinguishing the positions of the first magnetization portion at the front end side of the bending portion and the second magnetization portion at the base end side relative to the bending portion and the extension direction of the magnetic force lines. For example, when a load is applied to the front end of the medical device and deformation such as bending occurs in the medical device, the deformation is mainly at the front end side compared with the bending portion. Therefore, by taking the position of the second magnetization portion at the base end side relative to the bending portion and the extension direction of the magnetic force lines as a reference, even when a load is applied to the front end of the medical device, the detection accuracy of the three-dimensional movement of the portion provided with the first magnetization portion can be improved.

[0020] (7) In the medical device of the above scheme, it is preferred that the magnetic force lines of the first magnetized portion and the second magnetized portion extend in different directions. If such a structure is adopted, the accuracy of grasping the three-dimensional movement of the front end portion of the medical device can be further improved by detecting the extending directions of the magnetic force lines of the first magnetized portion and the second magnetized portion separately.

[0021] (8) In the medical device of the above aspect, preferably, a pair of permanent magnets whose magnetic force lines extend in the same direction as the magnetized portion are provided on both sides of the magnetized portion. With such a structure, it is possible to suppress a decrease in the magnetic force of the magnetized portion.

[0022] The present disclosure can be implemented in various aspects other than the above, and can be implemented in aspects such as a method for manufacturing a medical device, a system including a medical device and for detecting the position of a medical device inserted into a body, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the first embodiment.

[0024] Figure 2 : is a flowchart showing the method of manufacturing the mandrel.

[0025] Figure 3A It is an explanatory diagram showing a state of a magnetizing step of magnetizing the front end portion of the mandrel.

[0026] Figure 3B Yes means through Figure 3A An explanatory diagram of the magnetized portion formed by the magnetization step.

[0027] Figure 4A It is an explanatory diagram showing a state of a magnetizing step of magnetizing the front end portion of the mandrel.

[0028] Figure 4B Yes means through Figure 4A An explanatory diagram of the magnetized portion formed by the magnetization step.

[0029] Figure 5 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the second embodiment.

[0030] Figure 6 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the third embodiment.

[0031] Figure 7 : is a flowchart showing the method of manufacturing the mandrel.

[0032] Figure 8 It is a partial cross-sectional view showing the structure of the distal end portion of a guide wire according to a modified example of the third embodiment.

[0033] Fig. 9 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the fourth embodiment.

[0034] Fig.10This is an explanatory diagram showing a state in which a change in magnetic flux density is measured in the axial direction in a magnetized portion in which the magnetization direction is parallel to the axial direction.

[0035] Fig.11 This is an explanatory diagram showing a state in which a change in magnetic flux density is measured in the axial direction in a magnetized portion in which the magnetization direction is perpendicular to the axial direction.

[0036] Fig.12 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the fifth embodiment.

[0037] Fig.13 It is a partial cross-sectional view showing the structure of the distal end portion of the guide wire according to the sixth embodiment. DETAILED DESCRIPTION

[0038] A. First Implementation Method:

[0039] (A-1) Overall structure of the guidewire:

[0040] Figure 1 1 is a partial cross-sectional view showing the schematic structure of the guide wire 10 of the first embodiment. The guide wire 10 is a medical device formed in a long strip shape and inserted into the body from the front end. For example, it is used when inserting a catheter into a blood vessel or a digestive tract. The guide wire 10 includes a core shaft 20, an outer coil 30, a front end joint 40, and a base end joint 42. Figure 1 In the figure, the axis passing through the center of the guide wire 10 is represented by the axis O (single-dot chain line). In the present embodiment, the axis passing through the center of the core shaft 20 and the axis passing through the center of the outer coil 30 are both consistent with the axis O. However, the axis passing through the center of at least one of the core shaft 20 and the outer coil 30 may be different from the axis O. The direction in which the axis O extends is simply referred to as the "axial direction". In addition, Figure 1 The arrangement of each component is schematically shown, and the ratio of the dimensions of each component is not accurately shown.

[0041] exist Figure 1 and the following Figure 3A to Figure 7 , Figure 8 , Fig.12 , Fig.13 In the figure, mutually orthogonal XYZ axes are shown. The X axis corresponds to the axial direction of the guide wire 10, the Y axis corresponds to the height direction of the guide wire 10, and the Z axis corresponds to the width direction of the guide wire 10. Figure 1 The left side (-X axis direction) is called the "front end side" of the guide wire 10 and each component. Figure 1The right side (+X-axis direction) is called the "base end side" of the guide wire 10 and each component. In addition, of the two ends in the axial direction (X-axis direction) of the guide wire 10 and each component, the end located on the front end side is called the "front end", and the other end located on the base end side is called the "base end". Furthermore, the end including the front end is called the "front end portion", and the end including the base end is called the "base end portion". The guide wire 10 is inserted into the body from the front end side, and is operated at the base end by a doctor or other surgeon. Figure 1 , a portion including the distal end portion of the guide wire 10 is shown.

[0042] The core shaft 20 is a long strip-shaped component extending along the axis O, and is arranged from the front end to the base end of the guide wire 10. In the present embodiment, the core shaft 20 has a circular cross section perpendicular to the axis O as a whole, but it can also be made into a different shape such as an elliptical cross section at least in part. The front end of the core shaft 20 is a tapered shape with a thick diameter on the base end side and a thin diameter on the front end side. Figure 1 , the case of a portion that is reduced in diameter toward the front end of the mandrel 20 is shown. At the front end of the mandrel 20, the degree of reduction in diameter toward the front end of the mandrel 20 does not need to be constant. For example, in addition to the portion that is reduced in diameter toward the front end, a portion with a constant cross-sectional diameter may also be provided, and as a whole, the mandrel 20 may be reduced in diameter toward the front end.

[0043] The mandrel 20 of the present embodiment is formed of stainless steel and has a martensite phase together with an austenite phase as a phase with a different crystal structure. Figure 1 As shown, the mandrel 20 is provided with a magnetized portion 22 at a portion of its front end side. The magnetized portion 22 includes magnetized martensitic stainless steel and is formed by magnetizing a portion of the mandrel 20. The mandrel 20 is also referred to as a "magnetized member". The magnetization of the mandrel 20 and the magnetized portion 22 are described in detail below.

[0044] The outer coil 30 is a substantially cylindrical member formed by spirally winding a wire 31 so that the core shaft 20 passes through the inner portion thereof. The outer coil 30 is provided to improve the flexibility and torque transmission performance of the distal end portion of the guide wire 10.

[0045] In the present embodiment, the outer coil 30 is a single coil formed by winding a single wire 31, but it may be a multi-wire coil formed by winding a plurality of wires 31, a single twisted wire coil formed by winding a single twisted wire formed by twisting a plurality of wires 31, or a multi-twisted wire coil formed by using a plurality of twisted wires formed by twisting a plurality of wires 31 and winding each twisted wire into a plurality of wires. In addition, a single coil, a plurality of coils, a single twisted wire coil, and a plurality of twisted wire coils may be arbitrarily combined to constitute the outer coil 30. The wire diameter of the wire 31 and the average coil diameter of the outer coil 30 (the average diameter of the outer diameter and the average diameter of the inner diameter of the outer coil 30) can be arbitrarily determined.

[0046] The wire 31 can be formed of, for example, a stainless steel alloy such as SUS304 or SUS316, a superelastic alloy such as a nickel-titanium alloy, a piano wire, a nickel-chromium alloy, a cobalt alloy, or other radio-transparent alloy. In addition, it can also be formed of a radio-opaque alloy such as gold, platinum, tungsten, tantalum, iridium, palladium, or an alloy containing these elements (e.g., platinum-nickel alloy). In addition, the wire 31 can also be formed of a known material other than the above.

[0047] The front end of the outer coil 30 is fastened to the front end of the core shaft 20 by the front end joint 40. On the other hand, the base end of the outer coil 30 is fastened to the core shaft 20 by the base end joint 42. The front end joint 40 and the base end joint 42 can be formed of metal brazing materials such as Ag-Sn alloy, Au-Sn alloy, Sn-Pb alloy, Pb-Ag alloy, etc. The front end joint 40 and the base end joint 42 can be formed of the same material or different materials. In addition, in order to fix the core shaft 20 and the outer coil 30, the guide wire 10 can also be provided with a fixing portion other than the front end joint 40 and the base end joint 42.

[0048] (A-2) Regarding the magnetization and magnetization part of the mandrel:

[0049] Next, the phase change of the stainless steel of the mandrel 20 and the formation of the magnetized portion 22 when the mandrel 20 is magnetized will be described.

[0050] Figure 2 2 is a flowchart showing a method for manufacturing the mandrel 20. When manufacturing the mandrel 20, first, a workpiece to be processed into the mandrel 20 is prepared (process T100). In the present embodiment, as the workpiece, a rod-shaped (solid) or tubular (hollow) part having a constant cross-sectional diameter and made of austenitic stainless steel (e.g., SUS304, SUS316, etc.) which is a paramagnetic body is prepared.

[0051] Next, the processed part is subjected to plastic working in such a manner that the processed part becomes a shape that is reduced in diameter toward the front end portion, thereby obtaining a magnetized part (process T110). Examples of plastic working include centerless grinding, drawing, spinning, and the like. By subjecting the processed part composed of austenitic stainless steel to the above-mentioned plastic working, austenite crystals undergo plastic-induced phase transformation to martensite crystals at locations where the processing strength is relatively strong, specifically, at locations where the degree of reduction in diameter is relatively large near the front end of the mandrel 20. That is, processing-induced martensitic phase transformation is induced, and at least a portion of the austenite phase becomes a martensitic phase that is a ferromagnetic body. Therefore, the magnetized part obtained by plastic working has a martensitic phase near its front end. In addition, the crystal structure of the stainless steel constituting the mandrel 20 and the magnetized part can be specified by X-ray diffraction measurement.

[0052] Then, near the front end of the magnetized member, an external magnetic field is applied to at least a portion of the portion subjected to plastic working to magnetize the magnetized portion 22 (step T120), thereby completing the mandrel 20. The magnetizing device for generating the external magnetic field may generate a magnetic field capable of forming the magnetized portion 22, and may be, for example, a permanent magnet or an air-core coil that generates a magnetic field by passing an electric current.

[0053] Figure 3A 1 is an explanatory diagram showing a magnetization process in which the front end portion of the magnetized member 21 is magnetized using a magnetization device having an air-core coil 60. Figure 3B Yes means through Figure 3A FIG. 2 is an explanatory diagram of the magnetization portion 22 formed by the magnetization step shown in FIG. Figure 3A In the process, the part of the magnetized component 21 where the magnetized portion 22 is to be formed is placed in the air-core coil 60 and magnetized. Figure 3A In FIG. 1 , as an example, a case where the direction of the magnetic field in the air-core coil 60 is in the −X axis direction parallel to the axis O is shown by a dotted arrow.

[0054] Figure 4A 62 is an explanatory diagram showing a magnetization process in which the front end portion of the magnetized member 21 is magnetized using a magnetization device having a permanent magnet 62. Figure 4B Yes means through Figure 4A FIG. 2 is an explanatory diagram of the magnetization portion 22 formed by the magnetization step shown in FIG. Figure 4A In the embodiment, the permanent magnet 62 is arranged and magnetized so that the part of the magnetized component 21 where the magnetized portion 22 is to be formed is interposed and opposed. Figure 4A In FIG. 1 , as an example, a situation where the direction of the magnetic field generated by the magnetizing device is in the −Y-axis direction perpendicular to the axis O is shown by a dotted arrow.

[0055] like Figure 3B as well as Figure 4B As shown in FIG. 1 , the magnetized portion 22 is formed in a magnetization direction corresponding to the direction of the applied magnetic field. Figure 3A or Figure 4B By changing the direction of the magnetic field generated by the magnetizing device, the magnetization direction of the magnetized portion 22 can be arbitrarily adjusted. The stronger the external magnetic field applied by the magnetizing device, the stronger the magnetization of the magnetized portion 22. The stronger the magnetization of the magnetized portion 22, the better. It is best that the magnetization state of the magnetized portion 22 is saturation magnetization.

[0056] As the stainless steel constituting the processed part that becomes the mandrel 20, as long as stainless steel that is easy to undergo martensitic transformation by processing is used, it is easy to form the magnetized portion 22 with stronger magnetism. Even among austenitic stainless steels, for example, SUS304 is easy to undergo martensitic transformation by processing compared to SUS316, and SUS302 is more likely to undergo martensitic transformation. In addition, as stainless steel that is easy to undergo martensitic transformation by processing, stainless steel other than austenitic stainless steel can also be used. As stainless steel other than austenitic stainless steel that is easy to undergo martensitic transformation, for example, SUS444 and SUS434, which are ferrite stainless steels, or SUS630, which is precipitation hardening stainless steel, can be cited.

[0057] After the core shaft 20 is manufactured as described above, the front end of the core shaft 20 is inserted into the outer coil 30, and the front end of the core shaft 20 and the front end of the outer coil 30 are brazed to form the front end joint 40. In addition, the base end of the outer coil 30 and the core shaft 20 are brazed to form the base end joint 42. Thus, the guide wire 10 is obtained.

[0058] By inserting the guide wire 10 having the magnetized portion 22 at the front end into the body as described above, the strength and direction of the magnetic field in the body are detected, thereby being able to detect the position of the front end of the guide wire 10 in the body. In order to detect whether the guide wire 10 has invaded a certain position in the body, it is desirable that the position of the magnetized portion 22 is close to the front end of the guide wire 10.

[0059] In order to detect the position of the magnetized portion 22, a known magnetic sensor that can detect the intensity and direction of the magnetic field generated by the magnetized portion 22 can be used. As a magnetic sensor, for example, a GSR sensor (GHz-Spin-Rotation Sensor), a magnetoresistive element (MR), a magnetoresistive element (MI), and a superconducting quantum interference element (SUQUID) can be exemplified. In order to detect the position of the magnetized portion 22, for example, a magnetic sensor array that arranges multiple such magnetic sensors vertically and horizontally and is configured in a matrix shape can be used. The magnetic sensor array, for example, is configured on a table on which a human body lying as a treatment object using the guide wire 10 can be disposed. Alternatively, the magnetic sensor array can also be configured to be worn on a human body as a treatment object using the guide wire 10. When worn on the human body, the magnetic sensor array can be configured as a belt to be wound around the human body, or it can be configured as a clothing shape or a hat shape. In the above case, the magnetic sensor can be configured along the shape of the human body. In addition, a plate-shaped magnetic sensor array can also be configured three-dimensionally on at least one of the front and back surfaces of the human body and at least one of the two side surfaces of the human body.

[0060] According to the guide wire 10 of the present embodiment configured as described above, the magnetized portion 22 is formed by magnetizing the core shaft 20 originally provided in the guide wire 10. Therefore, unlike the case where a magnetized component such as a permanent magnet is further incorporated into the guide wire, the complexity and enlargement of the structure of the guide wire 10 can be suppressed, and the position of the front end portion of the guide wire 10 can be detected.

[0061] Furthermore, according to the present embodiment, since the magnetized portion 22 is formed by magnetizing the core shaft 20, it is possible to suppress the decrease in strength of the guide wire 10 caused by the formation of the magnetized portion 22, unlike the case where a member composed of a permanent magnet or the like is further inserted into the guide wire to form the magnetized portion. In addition, unlike the case where a member composed of a permanent magnet or the like is further inserted into the guide wire to form the magnetized portion, the risk of the formed magnetized portion being peeled off from the guide wire 10 can be suppressed.

[0062] Furthermore, according to this embodiment, since the magnetized portion 22 is provided, which includes magnetized martensitic stainless steel, it is not necessary to apply an external magnetic field when detecting the position of the guide wire 10. Therefore, the overall structure of the guide wire 10 and the system including the position detection device of the guide wire 10 can be suppressed from becoming complicated and large.

[0063] In the present embodiment, the magnetization process of magnetizing the magnetized component 21 to form the magnetized portion 22 is performed before the assembly process of the guide wire 10, but a different structure may be used. For example, after the assembly process, specifically, after the magnetized component 21 without the magnetized portion 22 is brazed to the outer coil 30 to form the front end joint 40 and the base end joint 42, an external magnetic field may be applied to the core shaft 20 to which the outer coil 30 is joined. At this time, as long as the outer coil 30 is a component made of a material different from the ferromagnetic body, the outer coil 30 will not be magnetized, and only the core shaft 20 will be magnetized. In addition, in the case where the outer coil 30 contains a ferromagnetic body, the outer coil 30 can also be magnetized, and such a structure will be described later as the fifth embodiment.

[0064] B. Second Implementation Method:

[0065] Figure 5 is with Figure 1 The schematic structure of the front end of the guide wire 110 of the second embodiment is similarly shown in a partial cross-sectional view. In the second embodiment, the same reference numerals are used for the common parts of the guide wire 10 of the first embodiment. The guide wire 110 has a plurality of (in Figure 5 The guide wire 10 is different from the guide wire 10 in that the core shaft 120 (two magnetized portions 122a and 122b) replaces the magnetized portion 22.

[0066] In the guide wire 110, the magnetized portion 122a and the magnetized portion 122b are provided at a distance from each other in the axial direction of the guide wire 110. In the second embodiment, the magnetized portion 122a and the magnetized portion 122b are magnetized in different directions.

[0067] The magnetized portion 122a and the magnetized portion 122b can be formed by applying external magnetic fields of different directions to a specified portion of the magnetized component 21, specifically, to the portion where the magnetized portion 122a and the magnetized portion 122b are to be formed. Figure 3A as well as Figure 4A Specifically, for example, the magnetization portion 122a can be used Figure 3A The magnetized portion 122b can be formed by using the method shown in FIG. Figure 4A Thus, a magnetized portion that generates magnetic lines of force extending in the same direction as the direction of the applied external magnetic field is formed, and a magnetized portion 122a and a magnetized portion 122b are formed in which the directions in which the magnetic lines of force extend are different from each other. Figure 5 In each of the magnetized portions 122a and 122b, the extending direction of the magnetic lines of force, that is, the direction of the external magnetic field applied to the magnetized component 21, is shown by a blank arrow. Figure 5As an example, the extension direction of the magnetic force lines of the magnetized portion 122a is the -X direction (axial direction), and the extension direction of the magnetic force lines of the magnetized portion 122b is the -Y direction. In addition, as described in the first embodiment, the magnetization process for forming the magnetized portion 122a and the magnetized portion 122b can be performed before the assembly process of the guide wire 110 or after the assembly process.

[0068] If such a structure is used, the magnetized portions 122a and 122b are formed by magnetizing the core shaft 120 originally provided with the guide wire 110, so the same effect as the first embodiment can be obtained. In addition, in the core shaft 120, a plurality of magnetized portions 122a and 122b are provided at intervals in the axial direction, so the positions of these magnetized portions 122a and 122b are detected separately, so that the three-dimensional movement of the front end of the guide wire 110 (for example, the position of the front end of the guide wire 110, the direction and angle of the front end of the guide wire 110, etc.) can be grasped with better accuracy. The distance between the magnetized portion 122a and the magnetized portion 122b can be appropriately set according to the sensitivity of the magnetic sensor so that the magnetized portion 122a and the magnetized portion 122b can be distinguished.

[0069] Furthermore, according to the second embodiment, the extension directions of the magnetic lines of force of the magnetizing portion 122a and the magnetizing portion 122b are different. Therefore, by detecting the extension directions of the magnetic lines of force of the magnetizing portion 122a and the magnetizing portion 122b separately, the accuracy of grasping the three-dimensional movement of the front end portion of the guide wire 110 can be further improved. In addition, in the present embodiment, the extension directions of the magnetic lines of force of the magnetizing portion 122a and the magnetizing portion 122b are different, but the directions in which the magnetic lines of force extend can also be the same. In this case, by providing a plurality of magnetizing portions spaced apart from each other in the axial direction, the accuracy of grasping the three-dimensional movement of the front end portion of the guide wire 110 can be improved compared to the case of providing a single magnetizing portion.

[0070] The magnetization directions of the magnetized portions 122a and 122b may also be different from Figure 5 Different. In addition, when the magnetization direction of the magnetization portion 122a is different from the magnetization direction of the magnetization portion 122b, the magnetization direction of the magnetization portion 122a and the magnetization direction of the magnetization portion 122b may not be orthogonal. However, in order to accurately distinguish the magnetization portion 122a from the magnetization portion 122b, it is preferred that the angle formed by the extension direction of the magnetic force lines of the magnetization portion 122a and the extension direction of the magnetic force lines of the magnetization portion 122b is 20° or more, and more preferably 45° or more.

[0071] For example, when the magnetization directions of the magnetization parts 122a and 122b are parallel to the axial direction and in the same direction, there is a possibility that the magnetization parts 122a and 122b are magnetically coupled and the boundary becomes unclear. In contrast, when the magnetization directions of the magnetization parts 122a and 122b are parallel to the axial direction and in the opposite direction, there is a possibility that the attenuation of the magnetic force and the resulting performance degradation of the detection related to the magnetization parts are accelerated by canceling the magnetic forces between the magnetization parts 122a and 122b. In addition, when the magnetization directions of the magnetization parts 122a and 122b are perpendicular to the axial direction and in the same direction, there is a possibility that the magnetic force repulsion is caused between the magnetization parts 122a and 122b, and twist is applied to the guide wire 110, thereby reducing the operability of the guide wire 110. In view of this, when the magnetization directions of the magnetized portion 122a and the magnetized portion 122b are perpendicular to the axial direction and in opposite directions, there is the possibility that the magnetized portion 122a and the magnetized portion 122b form a magnetic circuit, the amount of magnetic lines of force reaching the magnetic sensor is attenuated, and the precision of the position specified by the magnetic sensor is reduced. In order to suppress the above-mentioned undesirable conditions and improve the precision of the three-dimensional movement of the front end portion of the guide wire 110, it is preferred that the angle formed by the extension direction of the magnetic lines of force of the magnetized portion 122a and the extension direction of the magnetic lines of force of the magnetized portion 122b is close to 90°.

[0072] In the second embodiment, regardless of whether the magnetization directions of the magnetization portion 122a and the magnetization portion 122b are the same, it is preferred that the magnetization direction of the magnetization portion 122a provided at the front end side is parallel to or closer to the axial direction. The core shaft 120 is a shape that decreases in diameter toward the front end, so the magnetization direction of the magnetization portion 122a formed at the front end side of the core shaft 120 with a relatively small diameter is close to the axial direction, thereby making it easy to ensure the distance between the N pole and the S pole of the magnetization portion 122a. Therefore, it is easy to form the magnetization portion 122a that generates a stronger magnetic field.

[0073] In the second embodiment, two magnetized portions 122a and 122b are provided, but three or more magnetized portions may be provided. In this case, in order to improve the accuracy of grasping the three-dimensional movement of the front end portion of the guide wire 110, it is preferred that the magnetic lines of force of at least two of the three or more magnetized portions extend in mutually different directions.

[0074] C. Third Implementation Method:

[0075] Figure 6 is with Figure 1A partial cross-sectional view schematically showing the structure of the front end portion of the guide wire 210 of the third embodiment is similarly shown. In the third embodiment, the same reference numerals are used for the common portions of the guide wire 10 of the first embodiment. The guide wire 210 is different from the guide wire 10 in that it includes a core shaft 220 formed with plating portions 224a, 224b instead of the core shaft 20. In the guide wire 210, magnetized portions 222a, 222b are formed in the region where the core shaft 220 and the plating portions 224a, 224b overlap.

[0076] The plating portions 224a and 224b are plating layers covering a designated portion of at least a portion of the surface of the core shaft 220, and are arranged at intervals from each other in the axial direction, and are formed of a magnetic material, that is, a ferromagnetic metal. Considering the stability of the guide wire 210 when inserted into the body, the magnetic material constituting the plating portions 224a and 224b is preferably a magnetic material of a platinum magnet, for example. Specifically, the magnetic material of the platinum magnet is an alloy with platinum as the main component and containing iron (Fe), niobium (Nb), cobalt (Co), etc. However, the plating portions 224a and 224b can also be formed by a ferromagnetic metal other than the above-mentioned platinum alloy. The plating portions 224a and 224b contain a material having a higher coercive force (intrinsic coercive force) HCJ than martensitic stainless steel. The coercive force HCJ of the plating portions 224a and 224b can be higher than the coercive force HCJ of the core shaft 220, and preferably the coercive force HCJ is higher than that of the martensitic stainless steel. The plated portions 224a and 224b are also referred to as “high coercivity layers.” The magnetized portions 222a and 222b are formed together with the mandrel 220 by magnetizing at least a portion of each of the plated portions 224a and 224b.

[0077] Figure 7 2 is a flowchart showing a method for manufacturing the mandrel 220. When manufacturing the mandrel 220, first, a workpiece to be processed into the mandrel 20 is prepared (step T200), and the prepared workpiece is subjected to plastic working to obtain a magnetized part 21 (step T210). Steps T200 and T210 are related to Figure 2 The process T100 and the process T110 are the same process.

[0078] Next, the front end of the magnetized member 21 subjected to plastic working is masked (step T220). In step T220, the magnetized member 21 is masked so as to cover a larger range than the range where the magnetized member 21 is immersed in the plating bath in the plating process described later. Then, a part of the mask formed in step T220 is removed (step T230). In step T230, the mask provided in the region where the plated portions 224a and 224b are to be formed in the magnetized member 21 is removed.

[0079] Then, a plating treatment is performed (process T240). In the present embodiment, the aforementioned platinum alloy film is formed by electrolytic plating, but a non-electrolytic plating treatment may also be used. The plating bath may be appropriately selected in such a manner that the aforementioned platinum alloy film can be formed. The plating treatment is performed by immersing the magnetized component 21 in the plating bath in process T240, thereby forming the plated portions 224a and 224b in the region where a portion shielded in process T230 is removed. After the plated portions 224a and 224b are formed, the magnetized component 21 is cleaned (process T250), the plating solution attached to the magnetized component 21 is removed, and the shielding on the magnetized component 21 is removed.

[0080] Then, an external magnetic field is applied to the portion of the magnetized component 21 where the plated portions 224a and 224b are formed, and the magnetized portions 222a and 222b are formed in the region overlapping with the plated portions 224a and 224b (step T260), thereby completing the mandrel 220. Step T260 is the same as Figure 2 The process of applying an external magnetic field is similar to the process T120 of the previous process. In the region where the external magnetic field is applied, the core shaft 220 and the plated portions 224a and 224b made of martensitic stainless steel are magnetized to form magnetized portions 222a and 222b. The application of the external magnetic field can be similar to the process T120 of the previous process. Figure 3A as well as Figure 4A The method is the same as described in Figure 6 In FIG. 1 , the direction in which the magnetic force lines extend in each of the magnetized portions 222a and 222b, that is, the direction of the external magnetic field applied to the magnetized component 21 to form the magnetized portions 222a and 222b, is shown by blank arrows. Figure 6 As an example, the magnetic force lines of the magnetized portion 222a extend in the -X direction (axial direction) and the magnetic force lines of the magnetized portion 222b extend in the -Y direction. However, the magnetization directions of the magnetized portion 222a and the magnetized portion 222b may also be different. Figure 6 At this time, the magnetization directions of the magnetized portion 222a and the magnetized portion 222b may be the same or different. In addition, as described in the first embodiment, the magnetization process (process T260) for forming the magnetized portions 222a and 222b may be performed before or after the assembly process of the guide wire 210.

[0081] In addition, in the magnetization step of step T260, Figure 3ASimilarly, when the portion of the magnetized component 21 where the plating portion is formed is arranged in the air-core coil 60 for magnetization, it is preferred that the length of the plating portions 224a and 224b in the axial direction is longer than the length of the air-core coil 60 in the axial direction. For example, the plating portions 224a and 224b only need to be about 1 mm longer in the axial direction, i.e., the +X direction and the -X direction, respectively, compared with the air-core coil 60. Thus, the expansion of the magnetic flux in the magnetized portion formed in the magnetization process can be suppressed. However, it is also possible to make the length of the plating portions 224a and 224b in the axial direction shorter than the length of the air-core coil 60 in the axial direction. In this case, the portion of the magnetized component 21 that is not covered by the plating portions 224a and 224b is also magnetized to form a magnetized portion.

[0082] According to such a structure, since the magnetized portions 222a and 222b are formed by magnetizing the core shaft 220 originally provided with the guide wire 210, the same effect as the first embodiment can be obtained. In addition, in the core shaft 220, a plurality of magnetized portions 222a and 222b are provided at intervals in the axial direction, so the same effect as the second embodiment can be obtained. Furthermore, the plated portions 224a and 224b made of a magnetic material are provided on the surface of the core shaft 220, and the magnetized portions 222a and 222b are formed by applying an external magnetic field to the portion where the plated portions 224a and 224b are formed, so that the magnetic field strength of the magnetized portions 222a and 222b can be increased compared to the case where the plated portions 224a and 224b are not provided. As a result, the difference between the magnetic field strength of the magnetized portions 222a and 222b and the magnetic field strength around the magnetized portions 222a and 222b can be increased, so the accuracy of detecting the position of the distal end portion of the guide wire 210 can be improved.

[0083] Furthermore, in this embodiment, since the plated portions 224a and 224b serving as the high coercivity layer are formed as metal plating layers, it is easy to reduce the thickness of the plated portions 224a and 224b, and it is possible to reduce the size of the core shaft 220 caused by the formation of the high coercivity layer. In addition, since the core shaft 220 is prevented from becoming thicker due to the plated portions 224a and 224b, it is possible to reduce the rigidity of the core shaft 220 from becoming undesirably high. In particular, in this embodiment, if Figure 6 As shown, at least a portion of the plated portion 224a is covered by the front end joint portion 40 and included in the front end joint portion 40. Therefore, the effect of suppressing the enlargement of the mandrel 220 caused by the provision of the plated portion 224a can be further improved. However, if the degree of enlargement of the mandrel 220 caused by the plated portion 224a is within the allowable range, the plated portion 224a may not be included in the front end joint portion 40. Alternatively, the base end portion of the plated portion 224b may be included in the base end joint portion 42 to suppress the enlargement of the mandrel 220 caused by the formation of the plated portion 224b.

[0084] In addition, if the enlargement and increase in rigidity of the core shaft 220 caused by the formation of the plated portions 224a and 224b are within the allowable range, the high coercivity layer can be formed by a method other than plating, or can be formed by a magnetic body other than metal. For example, the high coercivity layer can also be formed by magnetic ceramics such as ferrite. In addition, in a structure in which the high coercivity layer is formed by metal plating as in the present embodiment, the control of size and physical properties is relatively easy, and thus it is preferred.

[0085] Figure 8 is with Figure 1 Similarly, a partial cross-sectional view showing a schematic structure of the distal end portion of a guide wire 310 as a modified example of the third embodiment is shown. Figure 8 In Figure 6 The common parts of the guide wire 210 of the third embodiment shown are marked with the same reference symbols. The guide wire 310 is different from the guide wire 210 in that it also includes an intermediate joint 44. The intermediate joint 44 is arranged between the front end joint 40 and the base end joint 42 in the axial direction, and is made of the same metal brazing material as the front end joint 40 and the base end joint 42, so that the middle part of the outer coil 30 is fastened to the core shaft 220. The intermediate joint 44 is arranged between the plating part 224a and the plating part 224b in the axial direction. In addition, Figure 8 In the embodiment, the plating portion 224a and the magnetized portion 222a are arranged in a ratio Figure 6 The plating portion 224a and the magnetized portion 222a may be closer to the distal end than the intermediate joint portion 44. Figure 6 Similarly, the plated portion 224 a and the magnetized portion 222 a are formed to overlap with the front end joint portion 40 .

[0086] According to such a structure, the flux applied to the joint portion before brazing for forming the intermediate joint portion 44 is easily accumulated in the area between the plating portion 224a and the plating portion 224b by the portion where the diameter of the core shaft 220 is partially thickened. In addition, when a metal brazing filler metal is arranged in the area between the plating portion 224a and the plating portion 224b to form the intermediate joint portion 44, it is possible to suppress the molten metal brazing filler metal from flowing beyond the portion where the diameter of the core shaft 220 is partially thickened.

[0087] In the third embodiment and the modification of the third embodiment, two plating parts 224a and 224b are provided as high-coercivity layers, but the number of high-coercivity layers may be one or more than three. By magnetizing the high-coercivity layer together with the core shaft 220, the same effect of increasing the magnetic field strength of the magnetized part is obtained compared with the case where the high-coercivity layer is not provided. In the case where a plurality of high-coercivity layers are provided, the magnetized parts provided corresponding to at least two high-coercivity layers preferably have magnetic lines of force extending in mutually different directions as described in the second embodiment.

[0088] In addition, in the third embodiment, an external magnetic field is applied to each high-coercivity layer to form a magnetized portion in each high-coercivity layer, but a different structure may be adopted. For example, in the front end portion of the core shaft 220, in the region where the high-coercivity layer is formed in a larger range and overlaps with the continuously arranged high-coercivity layer, an external magnetic field may be applied individually at multiple locations spaced apart in the axial direction to set multiple magnetized portions. In this case, it is also preferred that the magnetic lines of force of at least two of the multiple magnetized portions extend in different directions.

[0089] D. Fourth Implementation Method:

[0090] Fig. 9 is with Figure 1 Similarly, a partial cross-sectional view showing a schematic structure of the distal end portion of a guide wire 410 according to the fourth embodiment is shown. Fig. 9 In Figure 5 The same reference numerals are used for the common parts of the guide wire 110 of the second embodiment. The guide wire 410 is different from the guide wire 110 in that the guide wire 410 has a bent portion γ at the front end portion, where the guide wire 410 is bent in a predetermined direction. Fig. 9 In the figure, the position of the bending portion γ is indicated by the black arrow γ. The bending portion γ refers to the portion where the axis extending from the base end side to a certain direction begins to bend. In the guide wire 410, the front end side of the bending portion γ is called the "pre-formed portion α", and the base end side of the bending portion γ is called the "straight portion β". By providing the pre-formed portion α at the front end of the guide wire, the operability of the front end of the guide wire is improved. For example, when the guide wire is inserted into a blood vessel for use, the blood vessel selectivity is improved. In addition, Fig. 9 It is shown in Figure 1 The XYZ axes are mutually orthogonal, but Fig. 9 , the X-axis corresponds to the axial direction of the preformed portion α of the guide wire 410 , the Y-axis corresponds to the height direction of the preformed portion α, and the Z-axis corresponds to the width direction of the preformed portion α.

[0091] In the guide wire 410, a magnetized portion 122a is provided in the preformed portion α, and a magnetized portion 122b is provided in the straight portion β. The magnetized portion 122a is also referred to as a "first magnetized portion", and the magnetized portion 122b is also referred to as a "second magnetized portion". In the present embodiment, the magnetized portion 122a is formed in a portion including the front end of the core shaft 120. The magnetized portion 122a may not include the front end of the core shaft 120, but as described later, it is preferred that the position of the magnetized portion 122a is close to the front end of the guide wire 410. In the present embodiment, the magnetized portion 122b is formed in a position where the end portion on the front end side of the magnetized portion 122b overlaps with the bend γ. The end portion on the front end side of the magnetized portion 122b may also be spaced apart from the bend γ, but as described later, it is preferred that the position of the magnetized portion 122b is close to the bend γ in the straight portion β.

[0092] Specifically, the distance from the bend γ to the second magnetized portion 122b can be set to a distance such that the direction of the straight portion β and the position of the bend γ can be determined with sufficient accuracy by detecting the second magnetized portion 122b with a magnetic sensor. For example, it is preferred that the distance between the end of the front end side of the magnetized portion 122b and the bend γ is shorter than the length of the preformed portion α in the axial direction. In addition, it is preferred that the distance between the end of the front end side of the magnetized portion 122b and the bend γ is shorter than the length of the magnetized portion 122b in the axial direction in the straight portion β. That is, it is preferred that the distance between the end of the front end side of the magnetized portion 122b and the bend γ is shorter than at least one of the length of the preformed portion α in the axial direction and the length of the magnetized portion 122b in the axial direction. In addition, in the fourth embodiment, the axial direction of the guide wire 410 is changed in the bend γ, but in such a manner, the magnetized portion 122a and the magnetized portion 122b are also set to be "spaced apart from each other in the axial direction".

[0093] The following describes a method for measuring the distance from the bend γ to the second magnetized portion 122b in the guide wire 410. For example, a magnetic sensor is used to measure the magnetic flux density along the surface of the guide wire 410 in the axial direction, and the distance from the bend γ to the second magnetized portion 122b can be known from the pattern of the change in the magnetic flux density. Specifically, first, a magnetized portion in the target guide wire is specified. The magnetized portion can be specified as a portion where magnetic particles are concentrated, for example, by configuring the target guide wire on a sheet encapsulated with magnetic particles. In addition, for an area larger than the specified magnetized portion, the magnetic flux density can be measured along the surface of the guide wire in the axial direction using a magnetic sensor.

[0094] Fig.10 This is an explanatory diagram showing, as an example, a situation where a change in magnetic flux density is measured in the axial direction in a magnetized portion where the magnetization direction is parallel to the axial direction. Fig.10 and the following Fig.11In the figure, the horizontal axis represents the distance from a predetermined origin to the base end side at the front end side of the magnetized portion of the object to be measured in the straight portion β of the guide wire, and the vertical axis represents the magnetic flux density. After the magnetized portion is designated as described above, the guide wire is rotated on the magnetic sensor about the axis in such a way that the magnetic sensor is in contact with the magnetized portion. At this time, if the direction of the magnetic flux density is not reversed, it can be determined that the magnetization direction is parallel to the axis direction. In the case where the magnetization direction is parallel to the axis direction, if the magnetic sensor is moved in the axis direction along the surface of the guide wire from the origin to the base end side, as shown in FIG. Fig.10 As shown in FIG. 1 , the magnetic flux density gradually increases to reach a positive peak value, then decreases, reverses to reach a negative peak value, and then increases again. The position a1 of the positive peak value is the end of the front end side of the magnetized portion, and the position a2 of the negative peak value is the end of the base end side of the magnetized portion. In addition, the distance L between the position a1 and the position a2 is the length of the magnetized portion in the axial direction. In addition, when the magnetization direction in the magnetized portion is opposite, the magnetic flux density is opposite in positive and negative.

[0095] Fig.11 As another example, in a magnetized portion where the magnetization direction is perpendicular to the axial direction, Fig.10 This is an illustration of a case where the change in magnetic flux density is measured in the same manner. After the magnetized portion is designated as described above, the guide wire is rotated on the magnetic sensor with the axis as the center in such a way that the magnetic sensor is in contact with the magnetized portion. At this time, if the direction of the magnetic flux density is reversed, it can be determined that the magnetization direction is perpendicular to the axis direction. If the magnetization direction is perpendicular to the axis direction, if the magnetic sensor is moved along the surface of the guide wire from the origin to the base end side in the axis direction, as shown in FIG. Fig.11 As shown, the magnetic flux density gradually increases and reaches the first positive peak, then sharply decreases and reverses positive and negative to reach the first negative peak. After that, the magnetic flux density increases to nearly 0, then decreases and reaches the second negative peak, then sharply increases and reverses positive and negative to reach the second positive peak, and then gradually decreases. The position b1 where the magnetic flux density becomes 0 between the first positive peak and the first negative peak is the end of the front end side of the magnetized portion, and the position b2 where the magnetic flux density becomes 0 between the second negative peak and the second positive peak is the end of the base end side of the magnetized portion. In addition, the distance L between the position b1 and the position b2 is the length of the magnetized portion in the axial direction.

[0096] In this way, the position of the end on the front end side and the end on the base end side in the axial direction of the magnetized portion are specified according to the pattern in which the magnetic flux density changes in accordance with the direction of magnetization, and the length of the magnetized portion in the axial direction can be specified as the distance between the end on the front end side and the end on the base end side. The positional relationship between the above-mentioned bend portion γ and the second magnetized portion 122b, in other words, the region from the bend portion γ to the position on the base end side corresponding to the length of the preformed portion α in the axial direction, or the region from the bend portion γ to the position on the base end side corresponding to the length of the second magnetized portion 122b in the axial direction can overlap with the second magnetized portion 122b. However, according to the above-mentioned positional relationship, the second magnetized portion 122b can be spaced apart from the bend portion γ toward the base end side.

[0097] exist Fig. 9 In the figure, the direction of the external magnetic field applied to the magnetized component 21 to form the magnetized portions 122a and 122b is shown by a blank arrow. In the fourth embodiment, the magnetization directions of the magnetized portions 122a and 122b are different, but they may be the same direction. However, as described in the second embodiment, in order to suppress the undesirable condition caused by the extension direction of the magnetic lines of force of the magnetized portion 122a being parallel to the extension direction of the magnetic lines of force of the magnetized portion 122b, the angle formed by the above two directions is preferably greater than 20°, more preferably greater than 45°, and preferably close to 90°. Here, the angle formed by the extension direction of the magnetic lines of force of the magnetized portion 122a and the extension direction of the magnetic lines of force of the magnetized portion 122b refers to the angle after the guide wire 410 is bent at the bending portion γ.

[0098] To manufacture the guide wire 410, for example, similar to the second embodiment, after manufacturing a guide wire having magnetized portions 122a and 122b, the manufactured guide wire is bent in a specified direction at a specified position to form a bent portion γ and set as the guide wire 410. Here, when magnetizing a predetermined portion of the magnetized component 21, specifically, a portion where the magnetized portion 122a and the magnetized portion 122b are to be formed, the bending angle of the bent portion γ to be formed later is considered, and the magnetization direction is set in such a way that the angle formed by the extension direction of the magnetic lines of force of the magnetized portion 122a and the extension direction of the magnetic lines of force of the magnetized portion 122b becomes a desired angle. The range where the magnetized portions 122a and 122b are formed is the range of the magnetized component 21 that is the same as the air-core coil 60 (see Figure 3A ), permanent magnet 62 (refer to Figure 4A ) etc. in a range that overlaps in a direction perpendicular to the axial direction of the magnetized component 21.

[0099] Alternatively, if the guide wire 410 is to be manufactured, the magnetization process may be performed after the bending portion γ is formed to form the magnetized portions 122a and 122b. In addition, the guide wire 410 may be shipped without the bending portion γ, and a doctor or other operator may bend the guide wire before use to form the bending portion γ. In this case, in order to specify the position where the bending portion γ is to be formed, a mark that allows visual confirmation of the position of the magnetized portion 122b from the outside may be attached to the surface of the guide wire. In addition, information related to the recommended bending angle may be provided together with the guide wire.

[0100] With such a structure, the magnetized portions 122a and 122b are formed by magnetizing the core shaft 120 originally provided with the guide wire 410, so that the same effect as the first embodiment can be obtained. In addition, since a plurality of magnetized portions 122a and 122b are provided at intervals in the axial direction of the core shaft 120, the same effect as the second embodiment can be obtained. Furthermore, since the bending portion γ is provided, the magnetized portion 122a is provided in the pre-formed portion α, and the magnetized portion 122b is provided in the straight portion 122β, the accuracy of grasping the three-dimensional movement of the front end portion of the guide wire 410 can be further improved. This effect will be further described.

[0101] For example, when the guide wire 410 is inserted into the body and used, when a load is applied to the front end of the guide wire 410 to cause deformation such as bending, the deformation is mainly caused on the front end side of the bend portion γ. In addition, the location where the magnetized portion 122b is formed in the straight portion β (specifically, the distance from the bend portion γ to the magnetized portion 122b) and the direction of magnetization in the magnetized portion 122b can be predicted. Therefore, by detecting the intensity and direction of the magnetic field of the magnetized portion 122b by the magnetic sensor, the axial direction of the straight portion β and the position of the bend portion γ can be known. In the fourth embodiment, the position of the bend portion γ obtained as described above and the axial direction of the straight portion β are used as a reference, and the intensity and direction of the magnetic field of the magnetized portion 122a detected by the magnetic sensor are used, so that the three-dimensional movement of the front end of the preformed portion α provided with the magnetized portion 122a can be detected with good accuracy.

[0102] In addition, at this time, as described above, by arranging the magnetized portion 122b at a position closer to the bent portion γ in the straight portion β, the magnetized portion 122b can be detected by the magnetic sensor, thereby improving the accuracy of specifying the position of the bent portion γ. As a result, the accuracy of detecting the state of the front end of the guide wire 410 can be further improved.

[0103] Furthermore, by making the extension direction of the magnetic force lines of the magnetized portion 122a different from the extension direction of the magnetic force lines of the magnetized portion 122b, the distance between the magnetized portions 122a and 122b can be made shorter. When the extension direction of the magnetic force lines of the magnetized portions 122a and 122b is parallel to the axial direction and in the same direction, in order to easily distinguish the two by the magnetic sensor, it is necessary to ensure the distance between the magnetized portions 122a and 122b to a certain extent. When the extension direction of the magnetic force lines of the magnetized portions 122a and 122b is parallel to the axial direction and in opposite directions, in order to suppress the magnetic forces of the magnetized portions 122a and 122b from canceling each other, it is necessary to ensure the distance between the magnetized portions 122a and 122b to a certain extent. In the case where the extension direction of the magnetic force lines of the magnetized parts 122a and 122b is different from the axial direction and is in the same direction as each other, in order to suppress the repulsion of the magnetic force between the magnetized parts 122a and 122b, it is necessary to ensure the distance between the magnetized parts 122a and 122b to a certain extent. In the case where the extension direction of the magnetic force lines of the magnetized parts 122a and 122b is different from the axial direction and is in the opposite direction to each other, in order to suppress the formation of a magnetic circuit between the magnetized parts 122a and 122b, it is necessary to ensure the distance between the magnetized parts 122a and 122b to a certain extent. If the extension direction of the magnetic force lines of the magnetized parts 122a and 122b is different as in the fourth embodiment, the above-mentioned undesirable condition can be suppressed and the distance between the magnetized parts 122a and 122b can be shortened. Therefore, the preformed part α can be made shorter. Depending on the object for which the guide wire is used (for example, whether it is inserted into any part of the body such as a blood vessel of the heart or a blood vessel of the lower limbs for use), the length of the preformed part α is sometimes limited. Since the length of the preformed portion α can be shortened, when the guide wire 410 is used, it is possible to suppress restrictions on the application and the object, and to exhibit higher performance.

[0104] In the guide wire 410 of the fourth embodiment, similarly to the third embodiment, a high coercivity layer may be provided in a region of the surface of the core shaft 120 that overlaps with a portion where the magnetized portions 122a and 122b are formed.

[0105] In the fourth embodiment, two magnetized portions 122a and 122b are provided, but three or more magnetized portions may be provided. In this case, in addition to the magnetized portion 122a provided at the front end of the preformed portion α and the magnetized portion 122b provided at the straight portion β, other magnetized portions are provided at the base end side of the magnetized portion 122a in the preformed portion α, so that the accuracy of detecting the state of the preformed portion α that is easily deformed can be improved.

[0106] E. Fifth Implementation Method:

[0107] Fig.12 is with Figure 1A partial cross-sectional view showing the schematic structure of the front end portion of the guide wire 510 of the fifth embodiment is shown in the same manner. In the fifth embodiment, the same reference symbols are given to the common portions with the guide wire 10 of the first embodiment. The guide wire 510 also includes an inner coil 50, and in addition to the magnetized portion 22 formed on the core shaft 20, it also includes a magnetized portion 522a formed on the outer coil 30, and a magnetized portion 522b formed on the inner coil 50, which is different from the guide wire 10. In the fifth embodiment, in addition to the core shaft 20, the outer coil 30 and the inner coil 50 are equivalent to "magnetized components". Fig.12 In FIG. 1 , the inner coil 50 is shown as an external shape rather than a cross section.

[0108] The inner coil 50 is a substantially cylindrical member arranged inside the outer coil 30 in a manner that the core shaft 20 passes through the inside. In the present embodiment, the inner coil 50 is a single coil formed by winding a wire 51, but it may be a multiple coil formed by winding a plurality of wires 51 into a plurality of wires, or a single twisted wire coil formed by winding a single twisted wire formed by twisting a plurality of wires 51, or a multiple twisted wire coil formed by using a plurality of twisted wires formed by twisting a plurality of wires 51 and each twisted wire is wound into a plurality of wires. In addition, the inner coil 50 may be formed by arbitrarily combining a single coil, a plurality of coils, a single twisted wire coil, and a plurality of twisted wire coils. The wire 51 constituting the inner coil 50 is formed to be thinner than the wire 31 constituting the outer coil 30, and the length of the inner coil 50 in the axial direction is formed to be shorter than the length of the outer coil 30 in the axial direction.

[0109] The wire 51 constituting the inner coil 50 of the present embodiment is formed of stainless steel, and has an austenite phase and a martensite phase as phases with different crystal structures. The inner coil 50 is formed by forming the wire 51 composed of stainless steel that causes a process-induced martensitic transformation into a coil shape, and causing a martensitic transformation in at least a portion of the metal structure constituting the wire 51. The magnetized portion 522b is formed by applying an external magnetic field to such an inner coil 50.

[0110] As the stainless steel causing the work-induced martensitic transformation constituting the wire material 51 , for example, austenitic stainless steels such as SUS304, SUS316, and SUS302, ferritic stainless steels such as SUS444 and SUS434, or precipitation-hardening stainless steel such as SUS630 can be used.

[0111] In the fifth embodiment, the wire 31 constituting the outer coil 30 is also formed of stainless steel that causes work-induced martensitic transformation, similar to the wire 51 , and martensitic transformation occurs in at least a portion of the metal structure constituting the wire 31 .

[0112] When assembling the guide wire 510, the front end of the core shaft 20 is inserted into the inner coil 50, and the inner coil 50 and the core shaft 20 are housed in the outer coil 30. Then, the front end of the core shaft 20 and the front ends of the outer coil 30 and the inner coil 50 are brazed to form a front end joint 40. In addition, the base end of the outer coil 30 and the core shaft 20 are brazed to form a base end joint 42, thereby completing the assembly of the guide wire 510. Then, an external magnetic field is applied to the assembled guide wire 510 to form a magnetized portion 22 on the core shaft 20, a magnetized portion 522a on the outer coil 30, and a magnetized portion 522b on the inner coil 50, thereby completing the guide wire 510. The application of the external magnetic field can be, for example, Figure 3A or Figure 4A The direction of the applied magnetic field can be set arbitrarily by the same method as described in . Thus, the magnetized portions 22, 522a, 522b can be formed at the same position in the axial direction in the core shaft 20, the outer coil 30, and the inner coil 50.

[0113] With such a structure, the magnetized portion 22 is formed by magnetizing the core shaft 20 originally provided on the guide wire 510, thereby obtaining the same effect as the first embodiment. In addition, in addition to the magnetized portion 22, the magnetized portion 522a of the outer coil 30 and the magnetized portion 522b of the inner coil 50 are provided, so that the magnetic field strength at the front end of the guide wire 510 is increased, and the accuracy of detecting the position of the front end of the guide wire 510 can be improved.

[0114] exist Fig.12 In the embodiment, magnetized portions 22, 522a, and 522b are formed on the core shaft 20, the outer coil 30, and the inner coil 50, respectively. In view of this, the core shaft 20, the outer coil 30, and a part of the inner coil 50 may be formed of a material different from the ferromagnetic body, and the magnetized portion may be provided only on other parts including martensitic stainless steel as a ferromagnetic body. For example, the core shaft 20 may be formed of a material different from the ferromagnetic body, and the magnetized portion may be provided only on the outer coil 30 and the inner coil 50. Alternatively, the magnetized portion 22 may be provided on the core shaft 20, or the magnetized portion 22 may not be provided on the core shaft 20, or the magnetized portion may be provided only on one of the outer coil 30 and the inner coil 50. As long as a magnetized portion including magnetized martensitic stainless steel is formed at the front end of the guide wire, the enlargement and increase in rigidity of the guide wire can be suppressed, and the position of the front end of the guide wire can be detected.

[0115] In addition, the inner coil 50 may not be provided as in the first embodiment, but the magnetized portion 22, 522a may be formed on the core shaft 20 and the outer coil 30. Alternatively, the external magnetic field may be applied only to the magnetized member 21 that becomes the core shaft 20, and the guide wire 510 may be assembled using the core shaft 20 formed with the magnetized portion 22. In this case, the outer coil 30 and the inner coil 50 can be magnetized by the magnetic force of the magnetized portion 22 formed on the core shaft 20.

[0116] When the core shaft 20 is provided with the magnetized portion 22 , a high coercivity layer may be provided in a region of the core shaft 20 that overlaps with a portion where the magnetized portion 22 is formed, similarly to the third embodiment.

[0117] In the fifth embodiment, the magnetized portion 22, 522a, 522b may be provided at one position in the axial direction, and the magnetized portion may be provided at the core shaft 20, the outer coil 30, and the inner coil 50 at multiple positions in the axial direction. The magnetized portions provided at the same position in the axial direction can be formed simultaneously as magnetized portions with the same magnetization direction. When the magnetized portions are provided at multiple positions in the axial direction, it is preferred that the magnetization directions are different in at least two positions, and the directions of the magnetic lines of force extending from the formed magnetized portions are different from each other.

[0118] In addition, when the magnetized portion is provided in multiple parts such as the core shaft 20 and the outer coil 30 among multiple parts in the axial direction, the guide wire may be provided with a bent portion γ as in the fourth embodiment. In this case, one of the multiple parts may be provided at the front end side than the bent portion γ, and another part may be provided at the base end side than the bent portion γ.

[0119] F. Sixth Implementation Method:

[0120] Fig.13 is with Figure 1 Similarly, a partial cross-sectional view schematically shows the structure of the distal end portion of a guide wire 610 according to the sixth embodiment. In the sixth embodiment, the same reference numerals are used for the common portions with the guide wire 10 according to the first embodiment. The guide wire 610 is different from the guide wire 10 in that it further includes magnets 70 and 72 .

[0121] The magnets 70 and 72 are permanent magnets, and are arranged on both sides of the magnetized portion 22 in the axial direction so as to sandwich the magnetized portion 22, and are fastened to the core shaft 20. The magnetic lines of force of the magnets 70 and 72 extend in the same direction as the magnetized portion 22. Fig.13In the figure, as an example, the direction of the external magnetic field applied to the magnetized part 21 as the core shaft 20 in order to form the magnetized portion 22 is shown by a blank arrow, and the direction of the magnetic poles of the magnets 70 and 72 is shown. As permanent magnets constituting the magnets 70 and 72, various known permanent magnets such as neodymium magnets, samarium cobalt magnets, ferrite magnets, and alnico magnets can be used. The structure of configuring the magnets 70 and 72 can be variously adopted. For example, the magnets 70 and 72 can be formed into a ring shape, and the core shaft 20 can be embedded in the annular hole. Alternatively, the magnets 70 and 72 can be configured in a manner that is in contact with the surface of the core shaft 20 and bonded to the surface of the core shaft 20.

[0122] If such a structure is used, magnets 70 and 72 having the same extension direction of magnetic lines of force as the magnetized portion 22 are arranged across the magnetized portion 22, thereby suppressing the decrease in the magnetic force of the magnetized portion 22. In this embodiment, the magnets 70 and 72 only need to suppress the demagnetization of the magnetized portion 22, and do not need to assist in the detection of the position of the front end of the guide wire 610, so that the guide wire 610 can be more compact. In particular, in this embodiment, as Fig.13 As shown, the magnet 70 is arranged in a manner embedded in the front end joint 40, so that the size increase and the increase in rigidity of the guide wire 610 caused by the installation of the magnet 70 can be suppressed. In addition, if the size increase and the increase in rigidity of the guide wire 610 are within the allowable range, the magnet 70 can also be arranged outside the front end joint 40. Although the magnets 70 and 72 do not need to be in contact with the magnetized portion 22, in order to improve the effect of suppressing the demagnetization of the magnetized portion 22, it is preferred that the distance between the magnets 70 and 72 and the magnetized portion 22 is close.

[0123] In addition, as in the third embodiment, a high coercivity layer may be provided in a region overlapping with the portion where the magnetized portion 22 is formed on the surface of the core shaft 20. Alternatively, as in the fifth embodiment, an outer coil 30 made of martensitic stainless steel may be used, and a magnetized portion 522a may be formed in the outer coil 30. In addition, as in the fifth embodiment, an inner coil 50 made of martensitic stainless steel may be further provided, and a magnetized portion 522b may be provided in the inner coil 50.

[0124] In the sixth embodiment, a magnetized portion 22 is provided on the core shaft 20, but a plurality of magnetized portions spaced apart from each other in the axial direction may also be provided. In this case, as in the fourth embodiment, a bending portion γ may be provided on the guide wire, one of the plurality of magnetized portions is provided on the front end side of the bending portion γ, and another magnetized portion is provided on the base end side of the bending portion γ. In the case where magnetized portions are provided at a plurality of locations in the axial direction of the core shaft 20, it is preferred that the directions of magnetization are different in at least two locations, and the directions of magnetic lines of force extending from the formed magnetized portions are different from each other. In the case where magnetized portions are provided at a plurality of locations in the axial direction, the magnets 70 and 72 fastened to the core shaft may be arranged in such a manner that the extension direction of the magnetic lines of force is parallel to the axial direction across the magnetized portions.

[0125] G. Other implementations:

[0126] (G1) In each of the above-mentioned embodiments, the processed part is formed of stainless steel that causes a processing-induced martensitic transformation, and an external magnetic field is applied to the magnetized part that undergoes a martensitic transformation as a result of processing to form a magnetized portion, but a different structure may be used. For example, stainless steel that is a ferromagnetic body, such as martensitic stainless steel (e.g., SUS410) or ferrite stainless steel (e.g., SUS430), may be used to make the entire part such as the core shaft, the outer coil, and the inner coil that are used to form the magnetized portion.

[0127] (G2) In each of the above-mentioned embodiments, the medical device provided with the magnetized portion for position detection is set as a guide wire, but a different structure may be adopted. The medical device may be, for example, a catheter, a catheter core, etc. in addition to the guide wire. In a medical device formed in a long strip shape and inserted into the body from the front end for use, a magnetized portion including magnetized martensitic stainless steel may be formed at the front end.

[0128] The present disclosure is not limited to the above-mentioned embodiments, and can be implemented in various structures within the scope of the main purpose. For example, in order to solve part or all of the above-mentioned problems, or to achieve part or all of the above-mentioned effects, the technical features in the embodiments corresponding to the technical features in each mode recorded in the summary column of the invention can be appropriately replaced or combined. In addition, if the technical features are not the content that must be described in this specification, they can be appropriately deleted.

[0129] Explanation of symbols

[0130] 10, 110, 210, 310, 410, 510, 610—guide wire, 20, 120, 220—core shaft, 21—magnetized component, 22, 122a, 122b, 222a, 222b, 522a, 522b—magnetized portion, 30—outer coil, 31—wire, 40—front end joint, 42—base end joint, 44—middle joint, 50—inner coil, 51—wire, 60—air core coil, 62—permanent magnet, 70, 72—magnet, 224a, 224b—plated portion.

Claims

1. A medical device, which is formed in an elongated shape and has a front end side inserted into the body for use, the medical device being characterized by comprising: A magnetized component having a magnetized portion formed at a portion of the front end side, the magnetized portion comprising magnetized martensitic stainless steel; A high coercivity layer, the high coercivity layer is formed in a manner covering at least a portion of the surface of the magnetized component, and comprises a material having a higher intrinsic coercivity than martensitic stainless steel, wherein: The magnetizing section and the magnetizing component together magnetize the high-coercivity layer; as well as A pair of permanent magnets are provided on both sides of the magnetized portion, and magnetic lines of force of the permanent magnets extend in the same direction as the magnetized portion.

2. The medical device according to claim 1, characterized in that: The magnetized component is a mandrel, The magnetized portion is provided at the front end portion of the core shaft.

3. The medical device according to claim 1, characterized in that: A plurality of the magnetized portions are provided at intervals from each other in the axial direction of the medical device.

4. The medical device according to claim 2, characterized in that: A plurality of the magnetized portions are provided at intervals from each other in the axial direction of the medical device.

5. The medical device according to claim 3, characterized in that: The magnetic force lines of at least two of the plurality of magnetized portions extend in directions different from each other.

6. The medical device according to claim 3, characterized in that: A bent portion formed by bending the medical device in a specified direction is provided at the front end of the medical device. A first magnetized portion, which is one of the plurality of magnetized portions, is provided on the front end side of the bent portion. The second magnetized portion, which is another one of the plurality of magnetized portions, is provided on the proximal side of the bent portion.

7. The medical device according to claim 6, characterized in that: The magnetic lines of force of the first magnetized portion and the second magnetized portion extend in directions different from each other.

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