Method for manufacturing guidewire and biosensor

Abstract

[Problem] To provide a guidewire which is coated with an insulating film on the conductive part without loss of diaphragm mobility, with a configuration in which the diaphragm and the conductive part are in a plane perpendicular to the axis direction. [Solution] This guidewire 10 is provided with a guidewire main body 30 which has a housing 34 with an internal space 34S, and a pressure sensor 11 which is positioned in the internal space 34S. The pressure sensor 11 is provided with: a sensor main body 12 which is perpendicular to the axial direction 30A of the guidewire main body 30 and has a distal end surface 12a that faces the distal end; a diaphragm 13 which is positioned on the distal end surface 12a; resistances 17 which, by deforming together with the diaphragm 13, change in electric resistance value; terminals 18 which are connected to the resistances 17; conductive wires 15 which are attached with solder 26 to the terminals 18; and an insulating film 23 which is electroplated on the portion of the terminals 18, the solder 26 and the conductive wires 15 exposed at the distal end surface 12a, and is not electroplated on the diaphragm 13.　

Description

[Technical Field]

[0001] The present invention relates to a guide wire that is inserted into a lumen of a living body and used to measure the pressure of a fluid within the lumen, and to a method for manufacturing a biosensor that is used in the guide wire. [Background technology]

[0002] A known method for measuring the pressure of a fluid within a lumen of a living body, for example, the blood pressure in a coronary artery, is to insert a guide wire equipped with a pressure sensor into the blood vessel. Patent Documents 1 and 2 disclose pressure measuring devices in which a pressure detection sensor is disposed inside a housing provided at the tip of a guide wire.

[0003] The above-mentioned sensor includes a diaphragm and a resistor attached to the diaphragm. When a guidewire is inserted into a blood vessel, blood pressure is applied to the diaphragm of the sensor. When the diaphragm bends due to blood pressure, the electrical resistance of each resistor changes. This changes the current flowing through the resistor. Furthermore, if multiple resistors are provided, a potential difference occurs between the resistors. Blood pressure is calculated based on this change in current and potential difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2010-540114 [Patent Document 2] Japanese Patent Application Publication No. 2018-38792 Summary of the Invention [Problem to be solved by the invention]

[0005] During measurement, a part of the sensor comes into contact with blood. Therefore, it is desirable to apply a waterproof and insulating coating to the sensor (especially the conductive part of the sensor). The conductive part is, for example, a terminal provided at the part where the conductive wire for connecting the sensor to the computing device is connected to the sensor.

[0006] However, the pressure measuring device disclosed in Patent Document 2 has the following problem: In this pressure measuring device, both the diaphragm and the terminal are located on a plane perpendicular to the axial direction of the guidewire. Therefore, if a coating is applied to this plane, the coating will be applied not only to the terminal but also to the diaphragm, making it difficult for the diaphragm to flex.

[0007] Therefore, it has been considered to coat only the terminals without coating the diaphragm. However, the surface on which the diaphragm and terminals are located is extremely small, less than the diameter of the lumen of the living body. In particular, by positioning the diaphragm on a surface perpendicular to the axial direction of the guidewire, there is an advantage that even if the diaphragm approaches the blood vessel wall, the pressure load on the blood vessel wall is less likely to affect the deformation of the diaphragm. However, on the other hand, it is difficult to mask and coat only a portion of such a surface (the diaphragm portion). Even if masking is possible, the masking accuracy is low, and there is a risk that part of the coating will end up on the diaphragm.

[0008] On the other hand, if a thin coating is applied to the entire surface where the diaphragm and terminals are located, the diaphragm becomes difficult to move, and the accuracy of pressure detection deteriorates.

[0009] The present invention was made in consideration of the above-mentioned circumstances, and its object is to provide a guide wire in which the diaphragm and the conductive portion are both located on a plane intersecting the axial direction of the guide wire, and in which the conductive portion is coated with an insulating film without impairing the mobility of the diaphragm. [Means for solving the problem]

[0010] (1) A pressure measurement wire according to the present invention comprises a guidewire body having a distal end portion with an internal space, and a sensor located in the internal space of the distal end portion. The sensor comprises a sensor body having a surface that intersects the axial direction of the guidewire body and faces the distal end, a diaphragm located on the surface, a resistor whose electrical resistance value changes when deformed together with the diaphragm, a terminal connected to the resistor, a conductive wire electrically connected to the terminal, and an insulating film that is electrodeposited on portions of the terminal and the conductive wire that are exposed at the surface but is not electrodeposited on the diaphragm.

[0011] According to the above configuration, the diaphragm is not coated with an insulating film, but the terminals and conductive wires, which are the conductive parts, are coated with an insulating film, so that the fluid can be prevented from coming into contact with the conductive parts without impairing the mobility of the diaphragm.

[0012] (2) The sensor body has a through hole that opens to the surface and extends in the axial direction, the terminal is located at least in the opening or the through hole, and the conductive wire is inserted through the through hole.

[0013] The portion of the conductive wire that is connected to the terminal can be coated with an insulating film, and the side of the conductive wire opposite the through hole relative to the surface can be easily covered with an insulator made of resin or the like.

[0014] (3) The sensor body is cylindrical, and the diameter of the surface is less than 0.5 mm.

[0015] Because the diameter of the surface is small, less than 0.5 mm, it is difficult to coat only the conductive parts on the surface. However, with the above configuration, the insulating film is electrocoated, so it is possible to coat only the conductive parts even on small surfaces, preventing coating on the diaphragm.

[0016] (4) Preferably, the insulating film is mainly composed of polyimide.

[0017] (5) The present invention provides a method for manufacturing a biosensor located in the internal space of a distal end of a guidewire body having an internal space, the method comprising: applying an insulating coating to terminals and conductive wires exposed on a surface of the sensor facing the distal end, but not to a diaphragm exposed on the surface. The method includes an electrodeposition step of applying a potential to the terminals through the conductive wires while immersing at least the surface of the sensor in a coating liquid; a water-washing step of washing away coating components contained in the coating liquid that have adhered to at least the diaphragm of the sensor; and a baking step of heating the coating components adhering to the sensor after rinsing.

[0018] According to the above manufacturing method, since the insulating film is applied to the surface by electrodeposition coating, only the terminals and conductive wires, which are the conductive parts on the surface, are coated with the insulating film. In other words, the diaphragm is not coated with the insulating film. Therefore, it is possible to prevent the fluid from coming into contact with the conductive parts without impairing the mobility of the diaphragm.

[0019] In addition, a potential is applied to the terminal through the conductive wire during the electrodeposition process. This eliminates the need to use wires other than the conductive wire when applying a potential during the electrodeposition process, and the need to attach the conductive wire after the electrodeposition process. Furthermore, by monitoring the current during the electrodeposition process, it is possible to determine when the formation of the insulating film has been completed. [Effects of the Invention]

[0020] According to the present invention, in a configuration in which the diaphragm and the conductive portion are both on a plane intersecting the axial direction of the guide wire, the conductive portion can be coated with an insulating film without impairing the mobility of the diaphragm. [Brief explanation of the drawings]

[0021] [Figure 1]FIG. 1 is a schematic diagram of a guidewire 10 according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a perspective view of the pressure sensor 11. [Figure 5] 5A to 5C are cross-sectional views taken along the line VV in FIG. [Figure 6] FIG. 6 is a view taken along the arrow VI in FIG. [Figure 7] FIG. 7 is a circuit diagram of a bridge circuit according to an embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing the electrodeposition process. [Figure 9] FIG. 9 is a schematic diagram showing the baking step. DETAILED DESCRIPTION OF THE INVENTION

[0022] A preferred embodiment of the present invention will be described below. It should be noted that this embodiment is merely one example of the present invention, and it goes without saying that the example can be modified without departing from the spirit and scope of the present invention.

[0023] [Guidewire 10] As shown in FIG. 1, the guidewire 10 according to this embodiment includes a guidewire body 30 and a pressure sensor 11 (an example of a sensor, a biological sensor) provided on the guidewire body 30. An arithmetic and control unit 40 is electrically connected to one end of the guidewire body 30. In FIG. 1, of the two ends of the guidewire body 30, the fixed end (the end connected to the arithmetic and control unit 40) is the proximal end (the right side in FIG. 1), and the free end (the tip when inserted into a blood vessel) is the distal end (the left side in FIG. 1). Hereinafter, in the guidewire body 30, the side on which the proximal end is located will be referred to as the proximal side, and the side on which the distal end is located will be referred to as the distal side.

[0024] The guidewire main body 30 is a long, thin cord that can be inserted into a blood vessel such as a coronary artery. The pressure sensor 11 is provided at the distal end of the guidewire main body 30. The calculation control unit 40 calculates blood pressure based on electrical information (voltage value) output from the pressure sensor 11. In other words, the guidewire 10 is used to measure blood pressure.

[0025] 1 to 3 show the axial line 30L of the guidewire body 30. In this specification, the directions relating to the components constituting the guidewire body 30, i.e., the axial direction 30A, the radial direction 30R, and the circumferential direction 30C, are defined as follows. The axial direction 30A, the radial direction 30R, and the circumferential direction 30C are defined based on the axial line 30L when the guidewire body 30 is in a straight state without bending or curving, i.e., the axial line 30L is a straight line. The axial direction 30A is a direction parallel to the axial line 30L and includes both the distal and proximal directions. The radial direction 30R is any direction perpendicular to the axial line 30L. The circumferential direction 30C is a direction around the axial line 30L.

[0026] [Guidewire body 30] As shown in Fig. 1, the guidewire body 30 includes a core wire 31, a distal guide portion 32, a first helix 33, a housing 34, a second helix 35, and a guide tube 38. As shown in Fig. 2, the guidewire body 30 includes a tapered pin 39. As shown in Fig. 3, the guidewire body 30 includes a connecting wall 36 and a distal wire 37.

[0027] As shown in FIG. 1 , the core wire 31 is a component that constitutes the framework of the guidewire body 30. The core wire 31 provides the guidewire body 30 with a certain level of mechanical strength against bending, so that the guidewire body 30 can be inserted into a blood vessel without bending. The core wire 31 is a cylindrical wire that extends from the proximal end to the distal end. The core wire 31 is made of, for example, medical stainless steel. The axial center line of the core wire 31 is parallel to the axial center line 30L.

[0028] The core wire 31 is more flexible on the distal side than on the proximal side. The core wire 31 has a small-diameter portion 31a located on the distal side, a large-diameter portion 31b located on the proximal side, and a tapered portion 31c connecting the small-diameter portion 31a and the large-diameter portion 31b. The small-diameter portion 31a and the large-diameter portion 31b each have a constant outer diameter, and the outer diameter of the large-diameter portion 31b is larger than the outer diameter of the small-diameter portion 31a. The outer diameter of the tapered portion 31c is equal to the outer diameter of the large-diameter portion 31b at the proximal end, gradually decreases from the proximal end to the distal end, and is equal to the outer diameter of the small-diameter portion 31a at the distal end. As the outer diameter of the core wire 31 gradually decreases toward the distal side, the rigidity of the core wire 31 decreases in the order of the large-diameter portion 31b, the tapered portion 31c, and the small-diameter portion 31a.

[0029] 2, the tapered pin 39 is disposed distally from the distal end of the core wire 31. Like the core wire 31, the tapered pin 39 is a component that constitutes the framework of the guidewire body 30, and provides the guidewire body 30 with a certain level of mechanical strength against bending.

[0030] The tapered pin 39 includes a shaft portion 39a located on the proximal side and a tapered portion 39b extending distally from the shaft portion 39a. The outer diameter of the shaft portion 39a is constant. The shaft portion 39a is inserted into the small-diameter portion 31a of the core wire 31. The shaft portion 39a is fixed to the small-diameter portion 31a, for example, by laser welding or adhesive. The outer diameter of the tapered portion 39b tapers distally. Therefore, the rigidity of the tapered portion 39b gradually decreases distally. The distal end of the guidewire body 30, in which the tapered pin 39 is disposed, easily bends, allowing the guidewire body 30 to be easily guided along a blood vessel. In addition, a groove 39c opening on the outer peripheral surface of the tapered pin 39 is formed parallel to the axial direction 30A from the proximal end of the tapered pin 39 to the proximal portion of the tapered portion 39b. Four conductive wires 15 (described later) of the pressure sensor 11 pass through the core wire 31 via the groove 39c and are connected to the calculation control unit 40.

[0031] As shown in Figures 1 and 2, the guide tube 38 is located outside the small diameter portion 31a of the core wire 31 in the radial direction 30R and covers the distal portion of the small diameter portion 31a. The guide tube 38 is cylindrical in shape. The axis of the guide tube 38 is parallel to the axis 30L. The guide tube 38 is fixed to the outer peripheral surface of the small diameter portion 31a of the core wire 31. The guide tube 38 is flexible. The guide tube 38 is made of, for example, a medical synthetic resin and is, for example, heat-welded to the outer peripheral surface of the core wire 31.

[0032] As shown in Figures 1 and 3, the tip guide portion 32 is disposed at the distal end of the guidewire body 30. When the guidewire body 30 is inserted into a blood vessel, the tip guide portion 32 abuts against the blood vessel wall, thereby guiding the direction of travel of the guidewire body 30 along the blood vessel. The tip guide portion 32 includes a hemispherical portion 32a located on the distal side and a cylindrical portion 32b extending proximally from the hemispherical portion 32a. The hemispherical portion 32a has a hemispherical shape that protrudes distally so as not to damage the blood vessel wall. The outer diameter of the hemispherical portion 32a is approximately equal to the outer diameter of the second helix 35. The cylindrical portion 32b protrudes proximally from the hemispherical portion 32a and has a cylindrical shape with an outer diameter smaller than that of the hemispherical portion 32a. By inserting the cylindrical portion 32b into the second spiral body 35, the tip guide portion 32 is positioned relative to the second spiral body 35, and the outer surfaces of the hemispherical portion 32a and the second spiral body 35 are smoothly connected without any steps. The material of the tip guide portion 32 is, for example, medical stainless steel.

[0033] As shown in FIGS. 1 and 3, a first helix 33 and a second helix 35 are provided on the distal side of the guidewire body 30. The first helix 33 and the second helix 35 have lower bending rigidity than the tapered pin 39, i.e., are more easily bent. The first helix 33 is formed of a wire wound in a helical shape. The first helix 33 is made of, for example, medical stainless steel. The axial line of the first helix 33 is parallel to the axial line 30L. As shown in FIGS. 2 and 3, the tapered portion 39b of the tapered pin 39 is inserted into the first helix 33. The first helix 33 has a proximal end 33a (see FIG. 2) and a distal end 33b (see FIG. 3). As shown in FIG. 2, the proximal end 33a is fixed to the outer circumferential surface of the tapered portion 39b of the tapered pin 39 by, for example, laser welding or an adhesive. As a result, the bending rigidity of the first helical body 33 is reinforced by the tapered pin 39 .

[0034] As shown in FIG. 1, a housing 34 (an example of a distal end portion) is provided on the distal side of the guidewire body 30. As shown in FIGS. 1 and 3, the housing 34 is cylindrical and has an internal space 34S. The pressure sensor 11 is housed in the internal space 34S of the housing 34. The material of the housing 34 is, for example, medical stainless steel. The axial line of the housing 34 is parallel to the axial line 30L. The distal end portion 33b of the first helix 33 is fixed to the proximal end portion of the housing 34 by, for example, laser welding or an adhesive.

[0035] The housing 34 has a plurality of through holes 34a. In this embodiment, the housing 34 has two through holes 34a. The through holes 34a penetrate the cylindrical wall of the housing 34 along the radial direction 30R. An internal space 34S of the housing 34 communicates with the outside via the through holes 34a. The two through holes 34a are arranged along the circumferential direction 30C of the guidewire body 30, spaced 180 degrees apart around the axial line 30L. The number of through holes 34a is not limited to two. The distance between the through holes 34a is not limited to 180 degrees around the axial line 30L.

[0036] As shown in FIGS. 1 and 3, the second spiral 35 is formed of a wire wound in a spiral shape. The second spiral 35 is made of, for example, medical stainless steel. The axis of the second spiral 35 is parallel to the axis 30L. As shown in FIG. 3, the second spiral 35 has a proximal end 35a and a distal end 35b. The proximal end 35a of the second spiral 35 is fixed to the distal end of the housing 34. The second spiral 35 and the housing 34 are fixed to each other by, for example, laser welding or adhesive. The cylindrical portion 32b of the tip guide 32 is inserted into the distal end 35b of the second spiral 35. The distal end 35b is fixed to the outer circumferential surface of the cylindrical portion 32b. The second spiral 35 and the tip guide 32 are fixed to each other by, for example, laser welding or adhesive.

[0037] The connecting wall 36 is a member for connecting the tip wire 37 to the housing 34. The connecting wall 36 is fixed to the distal end of the housing 34. The connecting wall 36 is made of, for example, a metal solder material.

[0038] The tip wire 37 reinforces the bending rigidity of the second helix 35. The tip wire 37 is, for example, a wire made of medical stainless steel. The axial line of the tip wire 37 is parallel to the axial line 30L. The proximal end of the tip wire 37 is fixed to the connecting wall 36. The distal end of the tip wire 37 is fixed to the cylindrical portion 32b of the tip guide portion 32 by, for example, laser welding or adhesive.

[0039] With the above-described configuration, the tapered pin 39 and the distal guide portion 32 are connected via the first helix 33, the housing 34, and the second helix 35. Furthermore, the housing 34 and the distal guide portion 32 are connected via the distal wire 37. The tapered pin 39 is fixed to the core wire 31. In this way, the guide wire body 30 itself (excluding the core wire 31) is supported by the core wire 31, providing it with mechanical strength.

[0040] With this configuration, when the guidewire body 30 is advanced into a blood vessel at the proximal end, the guidewire body 30 follows this operation and advances through the blood vessel without bending. Furthermore, when the distal guide portion 32 comes into contact with the blood vessel wall, the guidewire body 30 curves along the blood vessel wall.

[0041] [Pressure sensor 11] 3, the pressure sensor 11 is disposed in an internal space 34S of the housing 34. The proximal portion of the internal space 34S is almost entirely filled with the pressure sensor 11. On the other hand, the distal portion of the internal space 34S, i.e., the internal space 34S located distal to the pressure sensor 11, remains open. The through-hole 34a of the housing 34 opens into the distal portion of the internal space 34S.

[0042] As shown in FIGS. 3 to 6, the pressure sensor 11 includes a sensor body 12, a diaphragm 13, a bridge circuit 14, four conductive wires 15, a covering member 16, and an insulating film 23.

[0043] As shown in FIG. 4, the sensor body 12 has a cylindrical shape. The axis of the sensor body 12 is parallel to the axis 30L. The sensor body 12 has a distal end face 12a (an example of a face), a proximal end face 12b, and an outer circumferential surface 12c. The distal end face 12a and the proximal end face 12b are surfaces that are perpendicular to the axial direction 30A. The distal end face 12a faces the distal end. The proximal end face 12b faces the proximal end. The outer circumferential surface 12c faces the radial direction 30R. The sensor body 12 is made of a material such as single crystal silicon.

[0044] In this embodiment, the diameter of the sensor body 12 (the diameter of the cylindrical circle) is approximately 0.3 mm. That is, the diameters of the distal end face 12a and the proximal end face 12b are approximately 0.3 mm or less. Note that the diameter of the sensor body 12 (the diameters of the distal end face 12a and the proximal end face 12b) is not limited to approximately 0.3 mm. The diameter of the sensor body 12 is preferably less than 0.5 mm, but may be 0.5 mm or more.

[0045] The sensor body 12 is fitted with a diaphragm 13, a bridge circuit 14, and four conductive wires 15.

[0046] As shown in Figure 5, the sensor body 12 has a recess 21 on its distal end surface 12a. The recess 21 is intended to make the diaphragm 13 more easily deformable by the pressure of the fluid in the lumen. When viewed from the distal side of the sensor body 12, the recess 21 has a circular shape. The depth of the recess 21 in the axial direction 30A is constant. The axis of the recess 21 coincides with the axis of the sensor body 12.

[0047] 4 to 6, the sensor body 12 has four through holes 22. The four through holes 22 are arranged at 90-degree intervals around the axial center line of the sensor body 12 along the circumferential direction 30C. Each through hole 22 extends along the axial direction 30A and opens to both the distal end face 12a and the proximal end face 12b of the sensor body 12. When viewed from the axial direction 30A, the through holes 22 have a circular shape.

[0048] As shown in Figures 4 to 6, the diaphragm 13 is disposed on and fixed to the distal end surface 12a of the sensor body 12. The diaphragm 13 is made of, for example, single-crystal silicon and is formed by partially etching the sensor body 12. The diaphragm 13 has a circular shape when viewed from the axial direction 30A and a rectangular shape when viewed from the radial direction 30R. The axial line of the diaphragm 13 coincides with the axial line of the sensor body 12. The distal end surface 12a, the diaphragm 13, and the recess 21 are arranged coaxially. The outer diameter of the diaphragm 13 is larger than the diameter of the inner circumferential surface of the recess 21. The diaphragm 13 covers the entire opening of the recess 21. The portion of the diaphragm 13 covering the opening of the recess 21 is elastically deformable when an external force is applied.

[0049] 4, 6, and 7, the bridge circuit 14 is disposed on and fixed to the distal end surface 12a of the sensor body 12. The bridge circuit 14 includes four resistors 17 (17A, 17B), four terminals 18 (18A, 18B, 18C, 18D), and four connecting bodies 19. The bridge circuit 14 surrounds the diaphragm 13.

[0050] The bridge circuit 14 is a full-bridge circuit in which all four resistors 17 function as strain gauges for measurement. Therefore, the four resistors 17 are made up of two types of resistors with different resistance change characteristics. The two types of resistors are first resistors 17A and second resistors 17B. In this specification, when there is no need to distinguish between the first resistor 17A and the second resistor 17B, they will be referred to as resistors 17.

[0051] The four resistors 17 are fixed to the distal surface of the diaphragm 13. The resistors 17 are made of, for example, boron. When viewed from the axial direction 30A, the four resistors 17 are fixed to the outer periphery of the diaphragm 13. The four resistors 17 are arranged at 90-degree intervals around the axial center line of the sensor body 12 along the circumferential direction 30C. Here, the first resistors 17A and the second resistors 17B are arranged alternately along the circumferential direction 30C. The resistors 17 are previously insulated.

[0052] Both the first resistor 17A and the second resistor 17B are semiconductors that utilize the piezoresistance effect. The resistor 17 is fixed to the diaphragm 13, and therefore elastically deforms in accordance with the elastic deformation of the diaphragm 13. When the resistor 17 elastically deforms, the electrical resistance value of the resistor 17 changes. In other words, the resistor 17 changes its electrical resistance value as it deforms together with the diaphragm 13.

[0053] The first resistor 17A and the second resistor 17B have different shapes. The first resistor 17A and the second resistor 17B also have different attitudes relative to the diaphragm 13. These differences in shape and attitude result in the difference in the resistance change characteristics described above between the first resistor 17A and the second resistor 17B.

[0054] When viewed from the axial direction 30A, the first resistor 17A has a Π-shape. In its orientation relative to the diaphragm 13, the first resistor 17A has a circumferential component 51 and two radial components 52. The circumferential component 51 extends generally along the circumferential direction of the diaphragm 13. The radial components 52 extend generally along the radial direction of the diaphragm 13. The first resistor 17A is configured so that its electrical resistance value increases as the diaphragm 13 deforms when pressure is applied.

[0055] When viewed from the axial direction 30A, the second resistor 17B has a rectangular shape. In terms of its orientation relative to the diaphragm 13, the second resistor 17B is configured with a circumferential component that extends generally along the circumferential direction of the diaphragm 13. The second resistor 17B is configured so that its electrical resistance value decreases as the diaphragm 13 deforms when pressure is applied.

[0056] As shown in FIGS. 6 and 7 , the four terminals 18 are two input terminals 18A and 18C and two output terminals 18B and 18D of the bridge circuit 14. In this specification, when it is not necessary to distinguish between the input terminals 18A and 18C and the two output terminals 18B and 18D, they are referred to as terminals 18. The terminals 18 are made of, for example, solder. As shown in FIG. 5 , the four terminals 18 are four conductive layers provided corresponding to the four through holes 22 of the sensor body 12. The conductive layers of the four terminals 18 are exposed so that the conductive wires 15 can be soldered to them. The terminals 18 are laminated on at least one of the inner surfaces of the through holes 22 and the periphery of the opening of each through hole 22 on the distal end face 12 a. In this embodiment, the terminals 18 are laminated on the periphery of the opening of each through hole 22 on the distal end face 12 a.

[0057] 4 and 6, the four terminals 18 are arranged on the outside of the diaphragm 13 in the radial direction 30R. The four terminals 18 are arranged at 90-degree intervals around the axial center line of the sensor body 12 along the circumferential direction 30C. The four terminals 18 and the four resistors 17 are arranged alternately in the circumferential direction 30C. Each terminal 18 is arranged between two adjacent resistors 17 among the four resistors 17.

[0058] As shown in FIGS. 4 to 6 , four connecting bodies 19 are provided corresponding to four terminals 18, respectively. Each connecting body 19 is a conductive layer laminated around the opening of each through-hole 22 in the distal end surface 12a. In this embodiment, the surface of each connecting body 19 is insulated before the terminal 18 is electrically connected. The terminal 18 is then electrically connected to the insulated connecting body 19. Each connecting body 19 electrically connects two adjacent resistors 17 to a terminal 18 located between the two adjacent resistors 17. In this manner, the four resistors 17 and the four terminals 18 are electrically connected alternately.

[0059] As shown in FIG. 6, in the bridge circuit 14, the two input terminals 18A and 18C are spaced 180 degrees apart, and the two output terminals 18B and 18D are spaced 180 degrees apart. As shown in FIGS. 6 and 7, the bridge circuit 14 has two paths, one path 27 and the other path 28, from the one input terminal 18A to the other input terminal 18C. The one path 27 passes through the first resistor 17A, the one output terminal 18B, and the second resistor 17B. The other path 28 passes through the second resistor 17B, the other output terminal 18D, and the first resistor 17A. Here, the one input terminal 18A is the high-voltage side, and the other input terminal 18C is the low-voltage side.

[0060] When a voltage is applied between the two input terminals 18A and 18C, a voltage drop occurs in one path 27 across the first resistor 17A and then the second resistor 17B, and in the other path 28, a voltage drop occurs in the second resistor 17B and then the first resistor 17A.

[0061] When the diaphragm 13 is not pressurized, the first resistor 17A and the second resistor 17B are not deformed. At this time, the first resistor 17A and the second resistor 17B have the same electrical resistance. Therefore, no potential difference occurs between the two output terminals 18B and 18D.

[0062] On the other hand, when the diaphragm 13 is pressurized, the first resistor 17A and the second resistor 17B are deformed. As described above, when pressure is applied, the electrical resistance of the first resistor 17A increases and the electrical resistance of the second resistor 17B decreases. In other words, the voltage drop across the first resistor 17A is greater than the voltage drop across the second resistor 17B. Therefore, a potential difference is generated between the two output terminals 18B and 18D.

[0063] When the guidewire main body 30 is inserted into a blood vessel and blood pressure is applied to the pressure sensor 11, a potential difference is generated between the two output terminals 18B and 18D in accordance with the blood pressure. The magnitude of the blood pressure can be determined based on this potential difference.

[0064] As shown in FIG. 5 , the four conductive wires 15 are electrically connected to four terminals 18, respectively. The conductive wire 15 has a conductive wire body 15a made of a conductor and an insulating cover 15b made of an insulator. The insulating cover 15b covers the conductive wire body 15a except for both ends of the conductive wire body 15a. At the distal end of the conductive wire 15, the conductive wire body 15a is electrically and mechanically connected to the terminal 18 by soldering. Solder 26 fills the gap between the conductive wire body 15a and the terminal 18 and may also cover part of the terminal 18. The solder 26 closes the openings of the four through-holes 22 on the distal end surface 12a of the sensor body 12. Note that part of the solder 26 may penetrate into the four through-holes 22 of the sensor body 12.

[0065] One end of the conductive wire 15 is electrically connected to the pressure sensor 11 by connecting the conductive wire body 15a to the terminal 18. The conductive wire 15 extends from the one end and is inserted into the through-hole 22. Proximal to the through-hole 22, the conductive wire 15 passes through the core wire 31 via the groove 39c and is connected to the calculation control unit 40. In other words, one end of the conductive wire 15 is connected to the pressure sensor 11, and the other end of the conductive wire 15 is connected to the calculation control unit 40.

[0066] As shown in FIGS. 3 to 5 , the covering member 16 is provided on the proximal side of the sensor main body 12. In this embodiment, the covering member 16 is made of an adhesive. The covering member 16 may be made of an insulating material such as silicone, rubber, or resin, rather than an adhesive. The covering member 16 is fixed to the proximal end face 12b of the sensor main body 12 and protrudes proximally from the proximal end face 12b. The covering member 16 blocks the openings of the four through holes 22 in the proximal end face 12b of the sensor main body 12. In other words, the openings on both sides of the through hole 22 are each blocked by the solder 26 and the covering member 16. Note that a portion of the covering member 16 may extend into the four through holes 22 in the sensor main body 12.

[0067] 4, the covering member 16 is connected to and fixed to the tapered pin 39. As a result, the sensor body 12 is fixed to the tapered pin 39.

[0068] [Insulating film 23] 5, the insulating film 23 is electrodeposited on a portion of the distal end face 12a. Specifically, the insulating film 23 is electrodeposited on the terminals 18, solder 26, and conductive wires 15 arranged on the distal end face 12a, which are exposed at the distal end face 12a. In this embodiment, the conductive wires 15 and the terminals 18 are covered with solder 26 except for their peripheral edges, and the peripheral edges of the terminals 18 are not covered with solder 26. In other words, the insulating film 23 is electrodeposited on the peripheral edges of the terminals 18 and the solder 26 of the terminals 18, solder 26, and conductive wires 15 arranged on the distal end face 12a.

[0069] On the other hand, the insulating film 23 is not electrodeposited on the diaphragm 13 and the connector 19 arranged on the distal end surface 12a.

[0070] 4 and 6, the insulating films 23 are indicated by hatching. As shown in the figures, four insulating films 23 exist independently of each other on the distal end surface 12a.

[0071] The insulating film 23 is mainly composed of polyimide. However, the insulating film 23 may be mainly composed of any insulator other than polyimide, such as epoxy or urethane.

[0072] [Calculation control unit 40] As shown in Figure 1, the calculation control unit 40 has a power supply unit 41 that supplies current to the pressure sensor 11, a calculation unit 42 that processes the electrical information output from the pressure sensor 11, and a connector 43 connected to the four conductive wires 15.

[0073] The power supply unit 41 is configured to apply a voltage to the bridge circuit 14 of the pressure sensor 11 through two conductive wires 15 connected to two input terminals 18A, 18C (see FIGS. 6 and 7).

[0074] The calculation unit 42 acquires the voltage value output from the bridge circuit 14 of the pressure sensor 11 through two conductive wires 15 connected to two output terminals 18B, 18D (see FIGS. 6 and 7). The calculation unit 42 calculates the blood pressure acting on the pressure sensor 11 based on changes in the acquired output voltage value. The calculation unit 42 includes a memory 42a. More specifically, the calculation unit 42 calculates the blood pressure as follows.

[0075] The memory 42a stores the correspondence between the output voltage value and the blood pressure, for example, as one-to-one correspondence data. Therefore, when an output voltage value is obtained, the calculation unit 42 can identify the blood pressure corresponding to that output voltage value based on the correspondence stored in the memory 42a. In this way, the calculation unit 42 can calculate the blood pressure acting on the pressure sensor 11 based on the voltage value output from the pressure sensor 11.

[0076] [Example of using Guidewire 10] The guidewire 10 is used, for example, to measure blood pressure in a coronary artery. The guidewire main body 30 is inserted into the coronary artery with its distal end, on which the tip guide portion 32 is provided, at the forefront when inserting into the blood vessel. The position of the guidewire main body 30 in the coronary artery is determined based on the position of the tip guide portion 32 displayed on an X-ray fluoroscopic image of the blood vessel.

[0077] When pressure sensor 11 reaches the blood pressure measurement position in the coronary artery, insertion of guidewire main body 30 is interrupted. In this state, a constant voltage is supplied to pressure sensor 11 from power supply unit 41 by the user's operation.

[0078] In the blood vessel, blood flows into the internal space 34S of the housing 34, and the blood pressure acts on the surface of the diaphragm 13 of the pressure sensor 11. This causes the diaphragm 13 to elastically deform, and the electrical resistance values ​​of the four resistors 17 change accordingly.

[0079] The blood flow pulsates due to the movement of the heart, causing the blood pressure to repeatedly rise and fall. The four resistors 17 elastically deform in response to the pulsation of the blood flow. As a result, the electrical resistance values ​​of the four resistors 17 change in response to the pulsating blood pressure.

[0080] The calculation unit 42 of the calculation control unit 40 acquires the electrical information output from the pressure sensor 11. As described above, the calculation unit 42 calculates the blood pressure acting on the pressure sensor 11 based on this electrical information.

[0081] [Method of manufacturing pressure sensor 11] Hereinafter, a method for electrodeposition coating the insulating film 23 in the manufacturing process of the pressure sensor 11 will be described with reference to FIGS.

[0082] 8, the conductive wire 15 of the pressure sensor 11 is wound around a spool 90. At this time, a distal end 91 (the portion where the sensor body 12 is provided) and a proximal end 92 (the portion connected to the connector 43) of the conductive wire 15 are not wound around the spool 90. The spool 90 is rotatably fixed or supported by a plate 93. In this embodiment, the plate 93 is made of glass epoxy, but is not limited to glass epoxy.

[0083] The distal end 91 is immersed in a coating liquid 94 stored in a container 95. In this embodiment, the coating liquid 94 contains polyimide fine particles. The coating liquid 94 is appropriately selected depending on the type of insulating film 23 to be electrodeposited. The coating liquid 94 may also contain a substance other than polyimide.

[0084] The proximal end 92 is fastened to a plate 93 by a metal clip 96. A conductive wire 98 connected to the negative electrode of a power source 97 is also fastened to the clip 96. As a result, the proximal end 92 is electrically connected to the negative electrode of the power source 97 via the clip 96 and the conductive wire 98. An electrode 100 is connected to the positive electrode of the power source 97 via a conductive wire 99. The electrode 100 is immersed in the coating liquid 94 stored in a container 95. In this embodiment, the electrode 100 is made of stainless steel, but the material is not limited to stainless steel.

[0085] In the circuit configured as described above, the power supply 97 applies a predetermined voltage (50 V in this embodiment). As a result, a potential of 50 V is applied to the terminals 18 and solder 26 arranged on the distal end surface 12a of the sensor body 12. In this embodiment, the current is applied for 20 seconds. Also, in this embodiment, during the current application, the coating liquid 94 is stirred using a stirrer or the like. This causes the polyimide particles to diffuse. The application of the potential causes the polyimide particles to adhere to the distal end 91 immersed in the coating liquid 94. This process of applying the potential corresponds to the electrodeposition process.

[0086] Next, the distal end portion 91 is removed from the coating liquid 94 and washed. In this embodiment, the washing is performed with pure water. This washing washes away the polyimide particles adhering to areas other than the conductive portions (terminals 18 and solder 26) of the distal end surface 12a. In other words, while the polyimide particles adhering to the diaphragm 13 and the connecting body 19, which are non-conductive portions, are washed away, the polyimide particles remain adhering to the terminals 18 and solder 26. Note that the connecting body 19 is covered with an insulator, and therefore the polyimide particles do not adhere directly to the non-conductive portions. This washing process corresponds to the water washing process.

[0087] Next, the sensor body 12 at the distal end 91 is heated. In this embodiment, as shown in FIG. 9 , the distal end 91 is placed on a plate 93, and a weight 101 is placed near the distal end 91. In this state, the sensor body 12 is heated. The sensor body 12 is heated, for example, by blowing hot air toward the sensor body 12 or by placing the sensor body 12 in an oven or on a hot plate. When hot air is used as the heating method, placing the weight 101 near the distal end 91 prevents the sensor body 12 from shaking due to the blowing of hot air. Heating is performed, for example, at approximately 170 to 200°C for 30 minutes. The heating melts the polyimide particles adhering to the terminals 18 and solder 26, and the insulating film 23 is formed by subsequent cooling. Note that the heating time, temperature, and heating method for the pressure sensor 11 can be selected as appropriate from those described above. This heating process corresponds to the baking process.

[0088] [Effects of this embodiment] According to this embodiment, the diaphragm 13 is not coated with the insulating film 23, but the terminals 18, which are conductive parts (and, if the conductive wires 15 and solder 26 are exposed, the conductive wires 15 and solder 26 in addition to the terminals 18), are coated with the insulating film 23. This prevents the conductive parts from coming into contact with the fluid without impairing the mobility of the diaphragm 13.

[0089] Furthermore, according to this embodiment, the connection portion of the conductive wire 15 with the terminal 18 can be coated with the insulating film 23, while the opposite side of the through hole 22 from the distal end face 12a of the conductive wire 15 can be covered with the covering member 16.

[0090] Furthermore, if the diameter of the distal end face 12a is small, less than 0.5 mm (0.28 mm in this embodiment), it is difficult to coat only the conductive portion on the distal end face 12a. However, according to this embodiment, the insulating film 23 is electrocoated, so that even on the small distal end face 12a, only the conductive portion can be coated, and coating on the diaphragm 13 can be prevented.

[0091] Furthermore, according to this embodiment, the insulating film 23 can be thinned to, for example, about 1 to 5 μm. Also, the insulating film 23 is formed with a uniform thickness that follows the uneven shape even in portions having uneven shapes such as the terminals 18 and the solder 26. Furthermore, the presence or absence of the insulating film 23 can be clearly seen from the outside.

[0092] Furthermore, according to the above-described method for manufacturing the pressure sensor 11, the insulating film 23 is coated on the distal end face 12a by electrodeposition coating. This allows only the conductive portions of the distal end face 12a, namely, the terminals 18, the solder 26, and the conductive wires 15, to be coated with the insulating film 23. In other words, the diaphragm 13 is not coated with the insulating film 23. This prevents fluid from contacting the conductive portions without impairing the mobility of the diaphragm 13. Furthermore, by adjusting the potential and time in the electrodeposition process, the thickness of the insulating film 23 can be controlled in 1 μm increments. This prevents polyimide particles adhering to the distal end 91 from dripping onto the diaphragm 13 during the electrodeposition process. Furthermore, the insulating film 23 can achieve an insulation resistance value of 1 MΩ or higher during the electrodeposition process. This reduces the likelihood of pinholes forming in the insulating film 23 and facilitates the achievement of a uniform thickness.

[0093] Furthermore, according to the above-described method for manufacturing the pressure sensor 11, in the electrodeposition step, a potential is applied to the terminal 18 through the conductive wire 15. In other words, there is no need to use an electric wire other than the conductive wire 15 when applying a potential in the electrodeposition step, and then to attach the conductive wire 15 after the electrodeposition step.

[0094] [Variations] Although the embodiments of the present invention have been described in detail above, the above description is merely illustrative of the present invention in every respect. It goes without saying that various improvements and modifications can be made without departing from the scope of the present invention. Regarding each component of the guidewire 10 according to the above-described embodiment, components may be omitted, replaced, or added as appropriate depending on the embodiment. Furthermore, the shape and size of each component of the guidewire 10 may also be set as appropriate depending on the embodiment. For example, the following modifications are possible.

[0095] In the above embodiment, the sensor body 12 has a cylindrical shape, and the distal end face 12a is perpendicular to the axial direction 30A of the guidewire body 30. The sensor body 12 only needs to have the distal end face 12a facing the distal side, and the shape of the sensor body 12 and the angle of the distal end face 12a relative to the axial direction 30A are not limited. The sensor body 12 may have, for example, a rectangular column shape, and the distal end face 12a may be inclined relative to the axial direction 30A.

[0096] In the above embodiment, the shape of the diaphragm 13 is a disk shape. The shape of the diaphragm 13 is not limited as long as the diaphragm 13 can be elastically deformed in response to changes in pressure applied to the diaphragm 13. The diaphragm 13 is a plate-like member, and the shape of this plate-like member when viewed from the axial direction 30A may be any shape. The any shape may be, for example, a polygonal shape, including a square, a hexagon, an octagon, etc.

[0097] In the above embodiment, the four resistors 17 are arranged at 90-degree intervals around the axial line of the sensor body 12. The arrangement of the four resistors 17 is not limited to this. For example, the four resistors 17 may be arranged at uneven intervals around the axial line of the sensor body 12, such as intervals of 120 degrees, 60 degrees, 120 degrees, and 60 degrees, or intervals of 60 degrees, 90 degrees, 30 degrees, or 180 degrees.

[0098] In the above embodiment, the four through holes 22 for providing the four terminals 18 are arranged at 90-degree intervals around the axial line of the sensor body 12. The arrangement of the four through holes 22 is not limited to this. For example, the four through holes 22, like the four resistors 17, may be arranged at uneven intervals around the axial line of the sensor body 12, such as intervals of 120 degrees, 60 degrees, 120 degrees, and 60 degrees, or intervals of 60 degrees, 90 degrees, 30 degrees, and 180 degrees. Furthermore, in the above embodiment, the shape of the through holes 22 as viewed from the axial direction 30A is circular. The shape of the through holes 22 as viewed from the axial direction 30A may be, for example, a polygonal shape, and is not limited to this.

[0099] In the above embodiment, four resistors 17 and four terminals 18 are provided, but the number of resistors 17 and terminals 18 is not limited to four. The number of conductive wires 15 is determined depending on the number of resistors 17 and terminals 18. When the number of resistors 17 and terminals 18 is other than four, the pressure sensor 11 has a circuit different from the bridge circuit 14 of the above embodiment that causes all of the resistors 17 to function as strain gauges. Furthermore, the number of insulating films 23 is not limited to four.

[0100] In the above embodiment, the surface of each connecting body 19 is insulated before the terminal 18 is electrically connected. However, like the terminal 18, the insulating film 23 may be coated by electrodeposition coating. Furthermore, the electrical connection between the terminal 18 and the conductive wire 15 is not limited to the solder 26. For example, instead of the solder 26, the terminal 18 and the conductive wire 15 may be electrically connected by a conductive adhesive, or a member in which the terminal 18 and the conductive wire 15 are integrally formed in an electrically connected state may be used. [Explanation of symbols]

[0101] 10. Guidewire 11. Pressure sensor (sensor, biosensor) 12. Sensor body 12a... Distal end surface (surface) 13. Diaphragm 15 Conductive wire 17. Resistor 18... terminal 22...Through hole 23. Insulating film 30 Guidewire body 30A...Axial direction 34 Housing (distal end) 34S...Internal space

Claims

1. a guidewire body having a distal end with an interior space; a sensor located in the interior space of the distal end; The sensor is a sensor body having a surface that intersects the axial direction of the guidewire body and faces the distal end; a diaphragm located on the surface; a resistor whose electrical resistance value changes when deformed together with the diaphragm; a terminal connected to the resistor; a conductive wire electrically connected to the terminal; the sensor body has a through hole that opens to the surface and extends in the axial direction, the terminal is located at least one of a periphery of the opening on the surface and an inner surface of the through hole, the conductive wire is inserted into the through hole and electrically connected to the terminal by a conductive material that closes the opening; The guide wire further comprises an insulating film that is electroplated in the shape of the conductive parts, including the terminals, the conductive wires, and the conductive material, among the exposed parts on the surface, and that is not electroplated on parts other than the conductive parts, including the diaphragm.

2. 2. The guidewire of claim 1, wherein the sensor body is cylindrical and the diameter of the surface is less than 0.5 mm.

3. 3. The guide wire according to claim 1, wherein the insulating film is mainly composed of polyimide.

4. A method for manufacturing a biological sensor, the method comprising: a sensor body having a surface facing the distal end of a guide wire body having a distal end with an internal space, the sensor body having a surface facing the distal end; a diaphragm located on the surface; a resistor whose electrical resistance value changes when deformed together with the diaphragm; a terminal connected to the resistor; and a conductive wire electrically connected to the terminal; the sensor body having a through hole that opens into the surface and extends in the axial direction; the terminal is located around the opening in the surface or on at least one of the inner surfaces of the through hole; the conductive wire is inserted into the through hole and electrically connected to the terminal by a conductive material that closes the opening; and a method for manufacturing a biological sensor, the method further comprising: electro-depositing a conductive portion, including the terminal, the conductive wire, and the conductive material, in the exposed portion of the surface in the shape of the conductive portion; and providing an insulating film that is not electro-deposited on portions other than the conductive portion, including the diaphragm, an electrodeposition step of applying a potential to the terminal through the conductive wire while at least the surface of the biosensor is immersed in a coating solution; a water washing step of washing away coating components contained in the coating liquid adhering to at least the diaphragm in the biological sensor; a baking step of heating the coating film components adhering to the biosensor after washing with water.

Images