Contact force sensor and device including contact force sensor

Abstract

The present invention provides a contact force sensor and a device including the contact force sensor. The contact force sensor has high accuracy and sensitivity and can ensure strength. The contact force sensor has a sensor body (2) manufactured by processing a semiconductor material. The sensor body (2) includes: an annular portion (21); a central portion (22) formed substantially at the center of the annular portion (21); spoke portions (23) connecting from the central portion (22) to the outside of the annular portion (21); and stress electrical conversion elements (5) disposed at opposite positions on the front side and the back side of the spoke portions (23) to convert the displacement of the spoke portions (23) into an electrical signal.

Description

Technical Field

[0001] The present invention relates to a contact force sensor suitable for use in the field of medical machines, and a device including the contact force sensor. Background Art

[0002] Conventionally, for example, an ablation catheter has been used to treat atrial arrhythmia. In ablation treatment using such an ablation catheter, the electrode of the ablation catheter is brought into contact with an abnormal site on the inner wall of the heart, and a high-frequency current is passed through to perform cauterization.

[0003] Therefore, a catheter having a contact force sensor provided at its tip is known, and the contact force sensor senses the contact force of the electrode (see Patent Document 1 and Patent Document 2).

[0004] However, in the structure shown in Patent Document 1, the sensor (strain gauge) is mounted on the arm by an adhesive, and the mounting position of the sensor is likely to deviate, resulting in a problem that it is difficult to adjust the output of the sensor. Moreover, since it is a mounting structure with an adhesive interposed, there is also a problem that the sensitivity of the sensor is reduced.

[0005] In addition, in the structure shown in Patent Document 2, the first sensor structure and the second sensor structure are joined by welding in a manner of sandwiching the sensor and the wire, so it is possible that the positions of the first sensor structure and the second sensor structure deviate. Moreover, since the joining is performed by welding, there is a problem that the strength is insufficient.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 5913812 Gazette

[0009] Patent Document 2: Japanese Patent No. 5697186 Gazette Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] In view of the above problems, an object of the present invention is to provide a contact force sensor and a device including the contact force sensor, which have high accuracy and sensitivity and can ensure strength.

[0012] Means for Solving the Problems

[0013] An embodiment of the present invention is a contact force sensor, which includes a sensor body fabricated by processing a semiconductor material. The sensor body includes: a ring portion; a central portion formed substantially at the center of the ring portion; spoke portions connecting the central portion to the ring portion on the outside; and stress electrical conversion elements disposed at opposite positions on the front side and the back side of the spoke portions, which convert the displacement of the spoke portions into electrical signals.

[0014] According to the above structure, it has high precision and sensitivity, and can ensure strength.

[0015] Moreover, a device including the contact force sensor includes the contact force sensor.

[0016] The contact force sensor is suitable for use in devices such as medical devices, but is not limited thereto. It can be applied to various devices that require miniaturization, and the applicable devices are not particularly limited.

[0017] Effects of the Invention

[0018] According to the embodiment of the present invention, a contact force sensor with high precision and sensitivity and capable of ensuring strength, and a device including the contact force sensor can be provided. Description of the Drawings

[0019] Figure 1A A plan view of a catheter showing the contact force sensor to which the embodiment of the present invention is applied, Figure 1B A schematic cross-sectional view for explaining the tip portion of the catheter.

[0020] Figure 2 A perspective view showing the contact force sensor.

[0021] Figure 3 A perspective view showing the contact force sensor disassembled.

[0022] Figure 4 A plan view showing the front side of the sensor body of the contact force sensor.

[0023] Figure 5 A plan view showing the back side of the sensor body of the contact force sensor.

[0024] Figure 6 A cross-sectional view along Figure 4 line A-A' in

[0025] Figure 7 A cross-sectional view along Figure 4 line B-B' in

[0026] Figure 8 A cross-sectional view along Figure 4 line C-C' in

[0027] Figure 9 It is an entity explanatory diagram for explaining the wiring relationship of the sensor body of the contact force sensor.

[0028] Figure 10 It is a bridge circuit diagram showing the connection state of the stress electrical conversion element.

[0029] [Explanation of symbols]

[0030] 1: Contact force sensor

[0031] 2: Sensor body

[0032] 21: Ring part

[0033] 22: Central part

[0034] 22a: Opening

[0035] 23: Spoke part

[0036] 23a: Protrusion

[0037] 24: Through hole

[0038] 3: Holding body

[0039] 4: Contact force transmission body

[0040] 4a: Interpenetrating hole

[0041] 5: Stress electrical conversion element (piezoresistive element)

[0042] 6: Wiring pattern

[0043] 61: Inner wiring pattern

[0044] 62: Outer wiring pattern

[0045] 7: Electrode

[0046] 7a: Electrode layer

[0047] 7b: Invasive part

[0048] 8: Insulating layer

[0049] 9: Conducting wire

[0050] 91: Insulating coating

[0051] 92: Conductor core wire part

[0052] 10: Duct

[0053] 11: Control handle

[0054] 12: Spindle

[0055] 13: Biasing member

[0056] 14: Tip electrode

[0057] S1-a to S4-d: Piezoresistive elements Detailed implementation manners

[0058] Hereinafter, with reference to Figures 1A to 10 the contact force sensor according to the embodiments of the present invention will be described. Figure 1A FIG. is a plan view showing an outline of a catheter to which the contact force sensor is applied, Figure 1B FIG. is a cross-sectional view for explaining a tip portion of the catheter, Figure 2 FIG. is a perspective view showing the contact force sensor, Figure 3 FIG. is a perspective view showing the contact force sensor disassembled. Figure 4 FIG. is a plan view showing a front side of a sensor body of the contact force sensor, Figure 5 FIG. is a plan view showing a back side of the sensor body. Figure 6 FIG. is a cross-sectional view along the Figure 4 A-A' line in Figure 7 FIG. is a cross-sectional view along the Figure 4 B-B' line in Figure 8 FIG. is a cross-sectional view along the Figure 4 C-C' line in. Moreover, Figure 9 FIG. is an entity explanatory view for explaining a connection relationship of a sensor body of the contact force sensor, Figure 10 FIG. is a bridge circuit diagram showing a connection state of stress electrical conversion elements. In addition, in each figure, the scales of the respective members are appropriately changed so that the respective members can be made recognizable sizes. Moreover, sometimes the tip side of the catheter is referred to as the front side, and the rear end side is referred to as the back side.

[0059] Regarding the contact force sensor according to the present embodiment, the following case is exemplified: incorporated into an ablation catheter, for performing ablation treatment, the contact force of the electrode of the ablation catheter against an abnormal part of the heart inner wall is measured, and thus it is applied to diagnosis and treatment.

[0060] As Figure 1A and Figure 1B shown, the catheter 10 is an ablation catheter, including a control handle 11 and a main shaft 12 led out from one end side of the control handle 11. Moreover, a biasing member 13 is provided on the control handle 11, and a tip electrode 14 is provided at the tip portion 12a of the main shaft 12. Further, a contact force sensor 1 is disposed inside the main shaft 12 at the tip portion 12a of the main shaft 12.

[0061] The biasing member 13 provided on the control handle 11 is a member for biasing and moving the top end portion 12a of the main shaft 12. By stretching an operation wire (not shown) disposed within the main shaft 12, the top end portion 12a of the main shaft 12 is biased and moved in two directions.

[0062] From the rear portion of the control handle 11, a cable 15 connected to a high-frequency generating device or a controller, or an infusion tube 16 connected to a fluid source is led out. The high-frequency generating device is connected to the tip electrode 14 to supply high-frequency energy to the tip electrode 14. Moreover, the controller has the following functions: controlling an electrical output signal or input signal to control the state of high-frequency energization to the tip electrode 14, or receiving an output signal from the contact force sensor 1 to measure the contact force.

[0063] The main shaft 12 is long and has a lumen, and has appropriate rigidity and flexibility. Moreover, within the lumen, hollow wire insertion tubes 17 and 18 are disposed along the length direction. The outer diameter dimension of the main shaft 12 is 8 French or less, and the length dimension is formed to be 900 mm to 1100 mm.

[0064] Moreover, the tip electrode 14 is formed in a bullet shape and fixed to the top end portion 12a of the main shaft 12. The tip electrode 14 has a cylindrical concave portion 14a on the back side. The contact force sensor 1 is connected to the concave portion 14a. Further, on the back side of the tip electrode 14, an electrode wire 14b is connected. The electrode wire 14b is inserted through the wire insertion tube 18 and connected to the high-frequency generating device. That is, the tip electrode 14 is electrically connected to the high-frequency generating device, and high-frequency energy is supplied from the high-frequency generating device to the tip electrode 14.

[0065] The outer diameter dimension of the tip electrode 14 is preferably substantially the same as the outer diameter dimension of the main shaft 12 and is formed to be 8 French or less. Moreover, as the material constituting the tip electrode 14, for example, a metal material having good thermal conductivity such as platinum, gold, stainless steel, or titanium alloy can be used.

[0066] In addition, in the tip electrode 14, a flow path (not shown) for sending out a fluid such as physiological saline conveyed from the infusion tube 16 to the outside is formed.

[0067] In such a catheter 10, when the tip electrode 14 contacts an abnormal portion of the heart inner wall, the stress applied to the tip electrode 14 due to the contact is transmitted to the contact force sensor 1, and the contact force can be measured.

[0068] Next, with reference to Figure 2 and Figure 3 the contact force sensor 1 will be described in detail.

[0069] The contact force sensor 1 is made of silicon semiconductor material by using the Micro ElectroMechanical System (MEMS) technology of semiconductor processing. The contact force sensor 1 includes a sensor body 2, a holding body 3, and a contact force transmission body 4.

[0070] The sensor body 2 is generally in a substantially short cylindrical shape and has: an annular portion 21; a central portion 22 formed substantially at the center of the annular portion 21; spoke portions 23 connecting from the central portion 22 to the outside to the annular portion 21; and a stress-electricity conversion element 5 disposed in the spoke portions 23.

[0071] The annular portion 21 is a cylindrical portion forming the outer contour of the sensor body 2. Inside the annular portion 21 and substantially at the center, a central portion 22 having a smaller diameter than the annular portion 21 is formed. In other words, an opening 22a is formed in the central portion 22 along the front-back direction.

[0072] The spoke portions 23 are formed from the outer wall side of the central portion 22 to the inner wall side of the annular portion 21 in the radial direction. Moreover, protrusions 23a are formed on both sides of the middle portion of the spoke portions 23, specifically, on both sides in the circumferential direction intersecting the radial direction. A plurality of spoke portions 23 are formed. Specifically, four spoke portions 23 are radially formed at intervals of 90 degrees around the central portion 22.

[0073] As shown in conjunction with Figure 4 and Figure 5 The stress-electricity conversion element 5 is formed on both the front side and the back side of the spoke portions 23. For the convenience of explanation, the stress-electricity conversion element 5 is represented by a solid line, but actually the stress-electricity conversion element 5 is formed in a manner of being integrally built into the sensor body 2. The stress-electricity conversion element 5 converts the displacement of the spoke portions 23 into an electric signal and is a piezoresistive element having a strain gauge function. When a strain is applied, the resistance changes according to the displacement.

[0074] The piezoresistive elements (S1-a, S1-b), (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b) are arranged on one side of the spoke portions 23, specifically, the front side, and are arranged on the center side and the outer peripheral side of each spoke portion 23. That is, a pair of piezoresistive elements (S1-a, S1-b), (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b) are arranged for each spoke portion 23. Moreover, electrodes 7 are formed on the protrusions 23a of the spoke portions 23 on which the piezoresistive elements (S1-a, S1-b), (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b) are arranged. The electrodes 7 are electrically connected to the power supply side.

[0075] Furthermore, on the front side, a wiring pattern 6 serving as a conductive layer is formed. On the inner peripheral side, an annular inner wiring pattern 61 is formed, and on the outer peripheral side, an annular outer wiring pattern 62 is similarly formed.

[0076] Moreover, the structure on the other side of the spoke portion 23, specifically the back side, is substantially the same as that on the front side. On the center side and the outer peripheral side of each spoke portion 23, a pair of piezoresistive elements (S1-c, S1-d), (S2-c, S2-d), (S3-c, S3-d), (S4-c, S4-d) are respectively arranged in the same manner as on the front side. Also, an electrode 7 is formed on the protruding portion 23a of the spoke portion 23. In addition, a wiring pattern 6 is similarly formed.

[0077] Such a stress electrical conversion element 5 is arranged at positions facing each other on the front side and the back side of the spoke portion 23. For example, taking the piezoresistive elements (S1-a, S1-b) on the front side and the piezoresistive elements (S1-c, S1-d) on the back side as a representative example to illustrate the arrangement relationship, the piezoresistive element (S1-a) and (S1-c) are arranged at facing positions, and the piezoresistive element (S1-b) and (S1-d) are arranged at facing positions. Also, the electrode 7 is arranged at positions facing each other on the front side and the back side.

[0078] Under the above arrangement relationship, as Figure 4 shown, the piezoresistive elements (S1-a) and (S1-b) on the front side are connected via the wiring pattern 6, and an electrode 7 is connected between the piezoresistive element (S1-a) and the piezoresistive element (S1-b). Furthermore, the piezoresistive element (S1-a) is connected to the inner wiring pattern 61, and the piezoresistive element (S1-b) is connected to the outer wiring pattern 62.

[0079] According to the connection relationship of such piezoresistive elements (S1-a, S1-b), (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b), the piezoresistive elements (S1-a, S1-b), (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b) are commonly connected to the inner wiring pattern 61 and the outer wiring pattern 62, so that the number of wires can be reduced and the wiring can be simplified. Also, as Figure 5 shown, regarding the piezoresistive elements (S1-c, S1-d), (S2-c, S2-d), (S3-c, S3-d), (S4-c, S4-d) on the back side, the same connection relationship is formed.

[0080] Next, with reference to Figures 6 to 8 the connection structure of the electrode and the wire will be described.

[0081] In the sensor body 2, a through hole 24 is formed from one surface side (front side) to the other surface side (back side). The through hole 24 is a hole through which a wire 9 for supplying power to the stress electrical conversion element 5 passes, and is formed between opposing electrodes 7 disposed on the front side and the back side.

[0082] Therefore, the through hole 24 is formed on the plane as Figure 4 and Figure 5 shown, on both sides of each piezoresistive element (S1-a, S1-b) and (S1-c, S1-d), (S2-a, S2-b) and (S2-c, S2-d), (S3-a, S3-b) and (S3-c, S3-d), (S4-a, S4-b) and (S4-c, S4-d), and specifically, on both sides in the circumferential direction intersecting the radial direction. Moreover, through holes 24a for connecting to the power supply line are formed facing each other in the radial direction. Specifically, there are eight through holes 24 formed on both sides of the piezoresistive element, and two through holes 24a for connecting to the power supply line, for a total of ten through holes 24, 24a formed.

[0083] The diameter size of the through hole 24 is preferably about, and in this embodiment, it is formed as μm.

[0084] On the front side and the back side surfaces of the sensor body 2, a wiring pattern 6 is formed by diffusion as a conductive layer. This conductive layer is electrically connected to the stress electrical conversion element 5.

[0085] Moreover, an insulating layer 8 is formed on the inner wall of the through hole 24, and the inner wall is covered by the insulating layer 8. Therefore, the inside of the through hole 24 is in a state where insulation is ensured. The insulating layer 8 also extends to the front side and the back side of the sensor body 2 and is formed. Regarding the insulating layer 8 on the front side and the back side of the sensor body 2, since the wiring pattern 6 and the wire 9 are electrically connected via the electrode 7, the wiring pattern 6 is covered in such a manner that a part of it is exposed as a part of the conductive layer. In addition, the insulating layer 8 is formed of a material such as silicon dioxide, and the thickness size is 1 μm to 2 μm.

[0086] Moreover, on the periphery of the front side and the back side of the through hole 24 and on the insulating layer 8, an electrode layer 7a is formed by a thin film forming technique such as sputtering. The electrode layer 7a is connected to the wiring pattern 6 at a partially exposed portion and is formed to extend slightly toward the inner wall side of the through hole 24. Regarding the material for forming the electrode layer 7a, for example, titanium / copper (Ti / Cu), aluminum-silicon alloy (Al-Si), and titanium / tungsten (Ti / W) can be used. In the case of a three-layer structure electrode layer, there is titanium / copper / gold (Ti / Cu / Au), etc.

[0087] The electrode 7 electrically connects the wire 9 to the stress electrical conversion element 5. The electrode 7 in this embodiment is composed of solder-plated filler metal. As the filler metal, for example, tin (Sn) which is a low melting point metal (melting point: 231.1 °C) can be used. Moreover, for the underlying plating, nickel (Ni) can be used. In addition, as the filler metal, indium (In) which is a low melting point metal (melting point: 156.6 °C) and ordinary welding materials can be used.

[0088] The wire 9 is an insulated coated wire in which the conductor core wire is formed of a copper-silver alloy (Cu-Ag) wire, has high buckling strength and tensile strength, and can greatly improve the strength compared with the case where the ordinary conductor core wire is made of copper (Cu). In particular, it is known that if the silver content is set to 3% to 15%, the strength is greatly improved. The wire 9 has an insulation coating 91 of perfluoroalkoxy alkane (PFA) resin which is a fluororesin. The bare conductor core wire portion 92 from which this insulation coating 91 has been peeled off is introduced through the through-hole 24 of the sensor body 2 in a manner that the tip portion is not bent and is straight.

[0089] Although the conductor core wire portion 92 of this wire 9 does not prevent direct contact with the electrode layer 7a, it does not directly contact the electrode layer 7a, but is joined by the filler metal which is the electrode 7. The filler metal is joined to the electrode layer 7a and is connected to the wiring pattern 6 and the stress electrical conversion element 5. Moreover, a part of the electrode 7 enters the inside of the through-hole 24 to form an intrusion portion 7b. Such a wire 9 is led out to the back side of the sensor body 2, and the end portion is connected to the control handle 11. In addition, regarding the diameter size of the conductor core wire portion 92 of the wire 9, it is preferably about, and in this embodiment, Therefore, a gap of about 10 μm is formed between the outer periphery of the conductor core wire portion 92 passing through the through-hole 24 and the inner wall of the through-hole 24.

[0090] Moreover, regarding the wire 9 led out from the back side of the sensor body 2, the led-out portion thereof can also be fixed using an adhesive such as epoxy resin.

[0091] Furthermore, the outer surface of the sensor body 2 and the outer surface of the portion fixed by the adhesive are preferably insulated and coated with a flexible insulating material in order to ensure waterproofness, insulation, and flexibility. At this time, Parylene (registered trademark) or a silicone coating material can be suitably used. In addition, the thickness dimension of the insulation coating becomes 2 μm to 3 μm.

[0092] Regarding machines for catheters and the like that are medical machines, in cases where the risk of these machines being exposed in the living body is high, for the materials used, it is required to be composed of materials that take into account biocompatibility. This is achieved by the following means: at least the outer surface of the sensor body 2 is coated with parylene (registered trademark), and the wire 9 is insulated and coated 91 with a fluororesin. In addition, the sensor body 2 uses a silicon material. It is confirmed that these materials have biocompatibility, ensuring safety.

[0093] According to the structure as described above, an insulating layer 8 is formed on the inner wall of the through-hole 24. Therefore, for the bare conductor core wire portion 92 from which the insulating coating 91 has been peeled off, insulation can be ensured while passing through the through-hole 24. Thus, under the limitation that the size of the through-hole 24 is extremely small in diameter, since the insulating coating 91 is peeled off and removed, a thick wire 9 with a conductor core wire diameter corresponding to the diameter of the through-hole 24 can be used. That is, a thick wire 9 with a core wire thickness close to the aperture diameter of the through-hole 24 can be used, increasing the tensile strength and improving the reliability.

[0094] Since the conductor core wire portion 92 of the wire 9 is thickened, after inserting and passing the conductor core wire portion 92 into the through-hole 24, by melting the solder for solder plating of the electrode 7, the wire 9 can be joined to the electrode layer 7a, making the joining process easier.

[0095] Moreover, the electrode 7 enters the inside of the through-hole 24 to form an intrusion portion 7b. Therefore, the connection state of the wire 9 becomes reliable, preventing the connection of the wire 9 from falling off.

[0096] Furthermore, the tip portion of the conductor core wire portion 92 of the wire 9 is not bent but is straight, and the electrode 7 is formed by solder plating. Thus, the protrusion amount to the one side of the sensor body 2 can be reduced. Moreover, the amount of solder obtained by solder plating can be reduced, reducing the stress applied to the spoke portion 23 of the sensor body 2.

[0097] Refer again to Figure 2 and Figure 3 The contact force sensor 1 will be described.

[0098] The sensor body 2 is mounted on a holding body 3 as a base member by bonding or wafer bonding, etc. Moreover, on the front side of the sensor body 2, a contact force transmission body 4 is mounted and provided by bonding or wafer bonding, etc.

[0099] The holding body 3 holds the sensor body 2, is in a substantially cylindrical shape with a hollow central portion, and is formed with an outer diameter dimension substantially the same as the outer diameter dimension of the sensor body 2. Moreover, a pair of claw-shaped portions 31 are formed on the front side, and when the sensor body 2 is combined with the holding body 3, the sensor body 2 is supported.

[0100] The contact force transmitter 4 has an insertion hole 4a formed in the central portion in the front-back direction, and is a two-stage member including a small-diameter portion 41 and a large-diameter portion 42. The small-diameter portion 41 is fitted into the opening 22a of the central portion 22 of the sensor body 2, and is arranged and joined to the sensor body 2 in such a manner that the back side of the large-diameter portion 42 is placed on the central portion 22.

[0101] Moreover, the diameter dimension of the sensor body 2 is formed The thickness dimension is formed to be 0.20 mm, the outer diameter dimension of the holding body 3 is formed The thickness dimension is formed to be 0.35 mm, the outer diameter dimension of the contact force transmitter 4 is formed The thickness dimension is formed to be 0.35 mm, and the dimension of the insertion hole 4a is formed In addition, it is preferably formed within a range of ±20% of the respective dimensions of the sensor body 2, the holding body 3, and the contact force transmitter 4.

[0102] Next, with reference to Figure 9 and Figure 10 The electrical connection state of the stress electrical conversion element (piezoresistive element) 5 will be described. Figure 9 This is an actual and schematic explanatory diagram for explaining the wiring relationship, showing the connection state of the wire 9 on the front side and the back side of the sensor body 2. In addition, regarding the piezoresistive element or the wiring pattern 6 on the back side of the sensor body 2, it shows the state of viewing the back side from the front side in perspective.

[0103] The piezoresistive elements (S1-a, S1-b) on the front side and the piezoresistive elements (S1-c, S1-d) on the back side are taken as representative examples for explanation. As Figure 9 shown, the wire 9 connected to the intermediate electrode 71a (right side in the drawing) between the piezoresistive elements (S1-a) and (S1-b) connected to the front side is connected to the electrode 72a (right side in the drawing) on the back side and led out. Moreover, the wire 9 connected to the electrode 71b (left side in the drawing) on the front side is connected to the electrode 72b (left side in the drawing) on the back side and led out. In addition, the voltage between the wires 9 is detected as the output voltage V 1 . In addition, the electrode 71b and the electrode 72a are insulated electrodes not electrically connected to the piezoresistive element. In addition, regarding the piezoresistive elements (S2-a, S2-b), (S3-a, S3-b), (S4-a, S4-b), (S2-c, S2-d), (S3-c, S3-d), (S4-c, S4-d), the same connection relationship also applies.

[0104] Moreover, electrodes 73a and 73b for connection to a power supply line are formed on the front side, and electrodes 74a and 74b for connection to the power supply line are similarly formed on the back side. A wire 9 connected to electrode 73a is led out by connecting to electrode 74a on the back side. A wire 9 connected to electrode 73b on the front side is led out by connecting to electrode 74b on the back side. In addition, a power supply E is connected between the wires 9. Further, electrodes 73a and 74a are connected to an outer wiring pattern 62, and electrodes 73b and 74b are connected to an inner wiring pattern 61.

[0105] As Figure 10 shown, a bridge circuit (full bridge circuit) is formed by four elements of piezoresistive elements (S1-a, S1-b) and (S1-c, S1-d), and an output voltage V is detected. 1 Similarly, a full bridge circuit is formed by four elements of piezoresistive elements (S2-a, S2-b) and (S2-c, S2-d), and an output voltage V is detected. 2 A full bridge circuit is formed by four elements of piezoresistive elements (S3-a, S3-b) and (S3-c, S3-d), and an output voltage V is detected. 3 A full bridge circuit is formed by four elements of piezoresistive elements (S4-a, S4-b) and (S4-c, S4-d), and an output voltage V is detected. 4 These four full bridge circuits are connected in parallel. The output voltage is output as strain is applied to the piezoresistive elements, and the output voltage is sent to a controller for arithmetic processing.

[0106] As described above, a full bridge circuit is constituted by a total of four stress electrical conversion elements 5, with two formed at opposite positions on each of the front and back sides of one spoke portion 23.

[0107] Next, a method of ablation therapy using the catheter 10 will be described. In ablation therapy, an abnormal site of the heart is determined in advance by mapping, and then the abnormal site of the inner wall tissue of the heart is cauterized to cause coagulative necrosis.

[0108] When cauterizing the abnormal site using the catheter 10, the catheter 10 is mainly inserted through the femoral vein or femoral artery located at the root of the thigh, and the tip of the catheter 10 is advanced into the heart while performing fluoroscopy by X-ray photography (roentgenography). Then, the control handle 11 is operated to bring the tip electrode 14 of the catheter 10 into contact with the abnormal site of the inner wall tissue of the heart, and a high-frequency current of, for example, 13.56 MHz is passed between the tip electrode 14 and the counter electrode located on the patient's back from a high-frequency generating device to cauterize the abnormal site.

[0109] At this time, the contact force sensor 1 is provided in the catheter 10, so that the contact force (stress) of the tip electrode 14 contacting the inner wall tissue of the heart can be detected. Specifically, the stress electrical conversion element (piezoresistive element) 5 formed in the contact force sensor 1 responds to minute strain and changes its resistance due to the applied strain.

[0110] If a contact force is applied to the tip electrode 14, the contact force is directly transmitted to the stress electrical conversion element (piezoresistive element) 5 via the contact force transmission body 4 and the spoke portion 23. In addition, the stress electrical conversion element (piezoresistive element) 5 three-dimensionally senses compressive / tensile strain.

[0111] For example, when stress is applied to the spoke portion 23 from a certain direction, the resistance value decreases when the piezoresistive element is compressed, and the resistance value increases when the piezoresistive element is stretched.

[0112] Therefore, the controller can be used to detect the Figure 10 output voltage V of the bridge circuit shown 1 、V 2 、V 3 and V 4 obtained three-dimensional differential output to measure the contact force. By measuring the contact force in this way, it can be applied to the diagnosis and treatment of ablation therapy.

[0113] As described above, according to the structure of the present embodiment, a contact force sensor with high precision, high sensitivity and ensured strength can be realized.

[0114] In addition, an insertion hole 4a is formed in the contact force transmission body 4, but a physical quantity sensor such as a temperature sensor or a pressure sensor may be arranged on the inner wall of the insertion hole 4a. Thus, physical quantities such as temperature or pressure can be detected in addition to the contact force. Furthermore, a flow path member for delivering the fluid conveyed from the perfusion tube 16 may be inserted into the insertion hole 4a. Therefore, the use of the insertion hole 4a formed in the contact force transmission body 4 is not particularly limited and can function effectively as appropriate.

[0115] Furthermore, for example, the contact force transmission body of the above-described embodiment is preferably provided, but it is not necessarily required. The contact force can also be directly sensed by the sensor body.

[0116] Moreover, the contact force sensor is suitable for devices such as ablation catheters or guiding catheters used as medical devices, but is not limited thereto. It is also possible to apply it not only in the field of medical devices but also to various devices including a contact force sensor and requiring miniaturization. The applicable devices are not particularly limited.

[0117] The present invention is not limited to the structure of the described embodiments, and various modifications can be made without departing from the gist of the invention. Moreover, the described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made. These embodiments or their modifications are included in the scope or gist of the invention and are included in the invention described in the claims and its equivalent scope.

Claims

1. A contact force sensor, characterized in that, it includes: A sensor body, which is fabricated by processing a semiconductor material, wherein the sensor body includes: a ring portion; a central portion formed substantially at the center of the ring portion; spoke portions connecting from the central portion to the outside of the ring portion; and stress electrical conversion elements disposed at opposite positions on the front side and the back side of the spoke portions, converting the displacement of the spoke portions into electrical signals; The sensor body has: a through hole formed from one side to the other side, through which a wire electrically connected to the stress electrical conversion element passes, a gap is formed between the wire and the inner wall of the through hole, and an insulating layer is formed on the inner wall of the through hole, The wire is introduced in a manner passing through the through hole and is soldered to electrode layers around the through hole on the front side and the back side, thereby forming the gap.

2. The contact force sensor according to claim 1, characterized in that, Two stress electrical conversion elements are respectively formed on the front side and the back side of the spoke portions.

3. The contact force sensor according to claim 2, characterized in that, The stress electrical conversion elements are disposed on the center side and the outer peripheral side of the spoke portions.

4. The contact force sensor according to any one of claims 1 to 3, characterized in that, Electrodes are formed in the circumferential direction on both sides of the stress electrical conversion element disposed on the spoke portion.

5. The contact force sensor according to any one of claims 1 to 3, characterized in that, A plurality of spoke portions are formed.

6. The contact force sensor according to any one of claims 1 to 3, characterized in that, A wiring pattern for commonly connecting a plurality of stress electrical conversion elements is formed on the sensor body.

7. The contact force sensor according to any one of claims 1 to 3, characterized in that, An opening is formed in the central portion of the sensor body.

8. The contact force sensor according to any one of claims 1 to 3, characterized in that it includes: A holding body for holding the sensor body.

9. The contact force sensor according to any one of claims 1 to 3, characterized in that, A contact force transfer body is provided on the sensor body.

10. The contact force sensor according to claim 9, characterized in that, An insertion hole is formed in the contact force transfer body.

11. The contact force sensor according to claim 10, characterized in that, A physical quantity sensor is disposed in the insertion hole.

12. The contact force sensor according to any one of claims 1 to 3, characterized in that, The stress electrical conversion elements are bridged to form a bridge circuit.

13. The contact force sensor according to claim 1, characterized in that, In the through hole, a conductor core wire portion with the insulating coating removed, which is electrically connected to the stress electrical conversion element, passes through.

14. The contact force sensor according to claim 13, characterized in that, The top end portion of the conductor core wire portion passing through the through hole is linear.

15. The contact force sensor according to claim 13, It is characterized in that the conductor core wire of the wire is formed of a copper-silver alloy wire.

16. The contact force sensor according to claim 1, it is characterized in that the wire electrically connected to the stress electrical conversion element is connected by an electrode containing solder.

17. The contact force sensor according to claim 16, it is characterized in that the electrode is a low melting point metal.

18. The contact force sensor according to claim 16, it is characterized in that the electrode enters the inside of the through hole to form an intrusion part.

19. The contact force sensor according to claim 1, it is characterized in that the electrode layer is formed by extending toward the periphery of the through hole and the inner wall side of the through hole.

20. The contact force sensor according to any one of claims 1 to 3, it is characterized in that the outer surface of the sensor body is insulated.

21. The contact force sensor according to claim 20, it is characterized in that the insulation coating has flexibility.

22. The contact force sensor according to claim 20, it is characterized in that a material with biocompatibility is used for the insulation coating.

23. A device including a contact force sensor, it is characterized in that it includes: the contact force sensor according to any one of claims 1 to 22.

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