Pressure Sensors

Abstract

The present invention provides a pressure sensor which is small and has high reliability while ensuring insulation. The pressure sensor (1) comprises: a sensor body (2); a pressure sensor element (21) provided on one side of the sensor body (2); a through hole (24) formed from one side of the sensor body (2) to the other side, through which a wire (3) connected to the pressure sensor element (21) for supplying electricity passes; and an insulating layer (24a) formed on the inner wall of the through hole (24). In the through hole (24), a conductor core wire portion (32) from which the insulation coating of the wire (3) has been removed passes.

Description

Technical Field

[0001] The present invention relates to a pressure sensor suitable for use in the field of medical equipment. Background Art

[0002] Conventionally, for example, in the medical field, in the diagnosis by measuring the intracoronary pressure, a thin and flexible guide wire with a pressure sensor at the tip is inserted into the coronary artery to measure the blood pressure. When there is stenosis in the coronary artery, the blood pressure in the coronary artery is measured, and the ratio of the blood pressure inside the stenosis to the blood pressure just before the stenosis, that is, the myocardial blood flow reserve fraction, is evaluated.

[0003] When measuring the blood pressure of a human body and performing a diagnosis, in order to reduce the burden on the patient, the pressure sensor used must be small, have good insulation and be more reliable.

[0004] However, the structure of the conventional pressure sensor has a problem that it is difficult to realize a pressure sensor that satisfies the desired requirements.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Publication No. 61-168969

[0008] Patent Document 2: Japanese Patent Laid-Open No. 9-187515

[0009] Patent Document 3: Japanese Patent Publication No. 10-505269

[0010] Patent Document 4: Japanese Patent Publication No. 2010-540114

[0011] Patent Document 5: Japanese Patent Application Publication No. 2018-38792

[0012] Patent Document 6: Japanese Utility Model Publication No. 56-172954 Summary of the invention

[0013] Problems to be solved by the invention

[0014] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a pressure sensor which is compact, has insulation properties ensured, and has high reliability.

[0015] Technical means of solving problems

[0016] The pressure sensor of this embodiment includes: a sensor body; a pressure sensor element, which is arranged on one side of the sensor body; a through hole formed from one side of the sensor body to the other side, through which a wire connected to the pressure sensor element for supplying power passes; and an insulating layer formed on the inner wall of the through hole.

[0017] Furthermore, a conductor core portion of a lead wire electrically connected to the pressure sensor element, from which the insulation coating has been removed, passes through the through hole.

[0018] Effects of the Invention

[0019] According to the embodiment of the present invention, it is possible to provide a compact pressure sensor that ensures insulation and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view showing a pressure sensor according to an embodiment of the present invention.

[0021] Figure 2 It is a plan view showing the top end portion of the pressure sensor.

[0022] Figure 3 For along Figure 2 Cross-sectional view of line XX in .

[0023] Figure 4 A bridge circuit diagram showing the connection status of the pressure sensor.

[0024] Figure 5 A front view showing a system including a pressure sensor.

[0025] Figure 6 Also shown is a front view of a system including a pressure sensor.

[0026] [Explanation of Symbols]

[0027] 1: Pressure sensor

[0028] 2: Sensor body

[0029] 3: Wire

[0030] 31: Insulation coating

[0031] 32: Conductor core

[0032] 4: Connection terminal

[0033] 41: Connector terminal

[0034] 5: Adhesive material

[0035] 6: Insulation coating

[0036] 7: Guidewire

[0037] 21: Pressure sensor element

[0038] 22: Hollow

[0039] 23: Diaphragm

[0040] 24: Through hole

[0041] 24a: Insulation layer

[0042] 25: Conductive layer

[0043] 26: Electrode layer

[0044] 27: Electrode

[0045] 27a: Invasion

[0046] 100: System

[0047] 101: Control Devices

[0048] Amp: Amplifier DETAILED DESCRIPTION

[0049] Below, refer to Figures 1 to 5 A pressure sensor according to an embodiment of the present invention will be described. Figure 1 This is a front view of the pressure sensor. Figure 2 is a plan view of the top end of the pressure sensor, Figure 3 For along Figure 2 The cross-sectional view of line XX in FIG. Moreover, Figure 4 This is a bridge circuit diagram showing the connection status of the pressure sensor. Figure 5 and Figure 6 1 is a front view showing a system including a pressure sensor. In each figure, the scale of each component is appropriately changed to make each component a recognizable size.

[0050] The pressure sensor of this embodiment is configured to be miniaturized and suitable for incorporation into a catheter (a guide wire). The pressure sensor measures the blood pressure in the coronary artery, which is a body cavity.

[0051] like Figure 1 As shown, the pressure sensor 1 includes a sensor body 2, a wire 3, and a connection terminal 4. The wire 3 is connected to the sensor body 2, and the end of the wire 3 is connected to the connection terminal 4. The length of the pressure sensor 1 from the sensor body 2 to the end of the wire 3 is about 2000 mm, and is in a long strip shape.

[0052] like Figure 2 and Figure 3As shown, the sensor body 2 in the pressure sensor 1 is a semiconductor pressure sensor having a pressure sensor element 21, and the pressure sensor element 21 has a function of a strain gauge in which the resistance value changes according to its displacement when pressure is applied. The pressure sensor element 21 is a piezoresistance element, and the piezoresistance element is formed on one side of the sensor body 2 containing silicon material. In addition, the sensor body 2 is roughly quadrangular prism-shaped, and the size is preferably about 160μm to 240μm on one side, and is formed to 200μm in this embodiment. Moreover, similarly, the axial size is preferably about 160μm to 240μm, and is formed to 200μm in this embodiment.

[0053] By setting it as such a size of a sensor body, it can be easily inserted into a guide wire with an outer diameter of 360 micrometers and an inner diameter of 300 micrometers.

[0054] In detail, the sensor body 2 is manufactured by processing a silicon semiconductor material using MEMS (Micro Electro Mechanical System) technology. The sensor body 2 has a cavity 22 formed on one side (top side), a circular diaphragm 23 formed on the cavity 22, and a piezoresistance element as a pressure sensor element 21 formed on the diaphragm 23. When forming the piezoresistance element, an ion implantation method, which is a semiconductor process technology for implanting impurity ions into a silicon layer, is applied to implant boron into the silicon layer.

[0055] Furthermore, the piezoresistance element as the pressure sensor element 21 is formed in two pairs with different shapes on the outer periphery of the diaphragm 23, and a plurality of them are formed, a total of four. Specifically, each pair of pressure sensor elements 21a, 21a and 21b, 21b are arranged and formed in line symmetry. The reason for this is that, as will be described below, a full bridge circuit is formed as a bridge circuit in the connection of the pressure sensor 1 to achieve high sensitivity.

[0056] When pressure is applied to the pressure sensor 1 , the piezoresistive element is deformed by deformation of the diaphragm 23 caused by the cavity 22 , and the resistance value of the piezoresistive element changes according to the deformation. The electronic circuit processes the change to detect pressure.

[0057] The shape of the sensor body 2 is not limited to a quadrangular prism, and may be a polygonal prism, or may be a cylindrical shape. The shape is not particularly limited.

[0058] Furthermore, the sensor body 2 has a through hole 24 formed from one side (top side) to the other side (rear side). The through hole 24 is a hole through which the lead wire 3 connected to the pressure sensor element 21 passes, and a plurality of through holes 24 are formed on the outer peripheral side of the diaphragm 23, specifically four through holes. Figure 2 As shown, the four through holes 24 are arranged at intervals of 90 degrees on a circumference centered at the center of the quadrangular column shape and between the pressure sensor elements 21. That is, they are arranged at the corners of the square shape.

[0059] In addition, the through holes are not limited to four, and three through holes may be formed, for example, and two pressure sensor elements may be formed. In this case, as will be described below, a half-bridge circuit is formed as a bridge circuit in the connection of the pressure sensor 1. Furthermore, in a simplified structure, two through holes may be formed and one pressure sensor element may be provided.

[0060] Therefore, in the above-mentioned structure, at least two through holes are formed. The number of through holes and pressure sensor elements is not particularly limited. Moreover, the diameter of the through hole 24 is preferably In this embodiment,

[0061] On one surface side of the sensor body 2 , a wiring pattern is formed by diffusion as a conductive layer 25 . The conductive layer 25 is electrically connected to the pressure sensor element 21 .

[0062] Next, if Figure 3 As shown, an insulating layer 24a is formed on the inner wall of the through hole 24, and the inner wall is covered by the insulating layer 24a. Therefore, the insulation inside the through hole 24 is ensured. Moreover, the insulating layer 24a is also formed to extend to one side and the other side of the sensor body 2. For the insulating layer 24a on one side of the sensor body 2, since the conductive layer 25 (pressure sensor element 21) is electrically connected to the wire 3 via the electrode 27, the conductive layer 25 is covered in a manner that a part of the conductive layer 25 is exposed. In addition, the insulating layer 24a is formed of a material such as silicon dioxide, and the thickness dimension is 1μm to 2μm.

[0063] In addition, an electrode layer 26 is formed on the insulating layer 24a around one side of the through hole 24 by a thin film forming technique such as a sputtering method. The electrode layer 26 is connected to the conductive layer 25 at a partially exposed portion and is formed so as to slightly protrude toward the inner wall side of the through hole 24. As for the material forming the electrode layer 26, for example, titanium / copper (Ti / Cu), aluminum-silicon alloy (Al-Si), titanium / tungsten (Ti / W), etc. can be used. In the case of a three-layer structure electrode layer, titanium / copper / gold (Ti / Cu / Au) and the like are used.

[0064] The electrode 27 electrically connects the lead wire 3 to the pressure sensor element 21. The electrode 27 of this embodiment includes a solder plated brazing material. For example, tin (Sn) (melting point is 231.1°C) which is a low melting point metal can be used as the brazing material. In addition, nickel (Ni) can be used for the bottom plating. In addition, indium (In) (melting point is 156.6°C) which is a low melting point metal and a common solder can be used as the brazing material.

[0065] The conductor 3 is an insulated coated electric wire formed of a copper-silver alloy (Cu-Ag) wire as a conductor core wire, and has high flexural strength and tensile strength, and can greatly improve strength compared to a case where the conductor core wire is usually copper (Cu). In particular, it is known that if the silver content is set to 3% to 15%, the strength is greatly improved. The conductor 3 has an insulating coating 31 of a perfluoroalkoxyalkane (PFA) resin as a fluororesin, and the bare conductor core wire portion 32 from which the insulating coating 31 is peeled off and removed is introduced from the other side of the sensor body 2 through the through hole 24 to the one side of the sensor body 2, and the top end portion is not bent but is straight.

[0066] The conductor core part 32 of the wire 3 does not prevent direct contact with the electrode layer 26, but does not directly contact the electrode layer 26, but is joined via the solder as the electrode 27, and the solder is joined to the electrode layer 26, and is connected to the conductive layer 25 and the pressure sensor element 21. Moreover, the electrode 27 enters a part of the interior of one side of the through hole 24 to form an intrusion part 27a. This kind of wire 3 is led out to the other side of the sensor body 2, and the terminal end is connected to the connection terminal part 4. In addition, regarding the diameter size of the conductor core part 32 of the wire 3, it is preferred to use In this embodiment, Therefore, a gap of about 10 μm is formed between the outer periphery of the conductor core portion 32 passing through the through-hole 24 and the inner wall of the through-hole 24 .

[0067] Furthermore, the lead wire 3 led out from the other surface side of the sensor body 2 is fixed at its lead-out portion by an adhesive material 5. The adhesive material 5 can be made of, for example, epoxy resin.

[0068] Furthermore, the outer surface of the sensor body 2 and the outer surface of the portion fixed by the adhesive material 5 are insulated by a flexible insulating material 6 to ensure waterproofness, insulation and flexibility. For example, Parylene (registered trademark) or silicone coating material ( Figure 2 For the sake of convenience, the insulating coating 6 and the like are omitted in the figure.) In addition, the thickness of the insulating coating 6 is 2 μm to 3 μm.

[0069] The connection terminal portion 4 is a portion to which the lead-out terminal portion of the wire 3 is connected, and electronic components such as a circuit substrate are housed in a resin-made, substantially rectangular box body to form an electronic circuit. Specifically, the connection terminal portion 4 is provided with a detection control circuit or an amplifier circuit of the pressure sensor 1. In addition, a connector terminal 41 is provided on one side of the connection terminal portion 4 as an input / output terminal. By connecting the connector terminal 41 to a control device such as a monitor, the detection information obtained from the output of the pressure sensor 1 can be measured.

[0070] Next, refer to Figure 4 Describe the connection status of the pressure sensor. Figure 4 As shown, the pressure sensor 1 is connected to a power supply V + , bridged to form a full-bridge circuit. As described above, the pressure sensor 1 has four pressure sensor elements 21, and the series circuit of the pressure sensor elements 21a and 21b and the series circuit of the pressure sensor elements 21b and 21a are connected to the power supply V + In addition, an output terminal is connected in the middle of each series circuit, and the output terminal is connected to an amplifier Amp, and a differential output can be detected in the form of an output voltage Vout. Therefore, even a signal of a tiny pressure change can be detected, and high-sensitivity detection can be performed.

[0071] In addition, the bridge circuit may also be formed by a half-bridge circuit. In this case, two pressure sensor elements 21 of the pressure sensor 1 and two standard resistors are provided. Specifically, two series circuits of the pressure sensor element 21 and the standard resistor are connected to the power supply V + The output terminals are connected in parallel and connected in the middle of each series circuit. The output terminals are connected to the amplifier Amp, and the differential output is detected in the form of the output voltage Vout. In this connection state, the pressure sensor element 21 of the pressure sensor 1 is arranged in the sensor body 2, and the standard resistor and the amplifier Amp are accommodated in the connection terminal part 4.

[0072] According to the above structure, the insulating layer 24a is formed on the inner wall of the through hole 24, so that the bare conductor core part 32 from which the insulating coating 31 is stripped can pass through the through hole 24 while ensuring insulation. Therefore, under the limitation that the size of the through hole 24 is extremely small, since the insulating coating 31 is stripped and removed, the conductor core wire 3 with a correspondingly large diameter and thick can be used. That is, the conductor core wire 3 with a thick core wire close to the hole diameter of the through hole 24 can be used, and the tensile strength can be increased to improve reliability.

[0073] Since the conductor core 32 of the lead 3 can be made thicker, the conductor core 32 can be inserted into the through hole 24 and then the solder plated brazing material serving as the electrode 27 is melted, thereby joining the lead 3 to the electrode layer 26 , thereby facilitating the joining process.

[0074] Furthermore, since the electrode 27 enters the inside of the through hole 24 to form the intrusion portion 27 a , the connection state of the lead wire 3 becomes reliable, and the connection of the lead wire 3 can be prevented from being disconnected.

[0075] Furthermore, the tip of the conductor core wire portion 32 of the lead wire 3 is not bent but is straight, and the electrode 27 is formed by solder plating, so that the protrusion amount to one side of the sensor body 2 can be reduced. In addition, the amount of solder obtained by solder plating can be reduced, and the stress applied to the diaphragm 23 of the sensor body 2 can be reduced.

[0076] Furthermore, for medical devices such as catheters, when there is a high risk of exposure of these devices to the living body, the materials used are required to be made of materials that take into account compatibility with the living body. In this embodiment, at least the outer surface of the sensor body 2 and the outer surface of the portion fixed by the adhesive material 5 are coated with parylene (registered trademark), and the lead wire 3 is insulated with a fluororesin coating 31. In addition, the sensor body 2 uses a silicon material, and the adhesive material 5 uses an epoxy resin. These materials have been confirmed to have compatibility with the living body and can ensure safety.

[0077] Next, refer to Figure 5 , a system including a guide wire 7 incorporating the pressure sensor 1 will be described.

[0078] The system 100 of this embodiment includes a well-known guide wire 7 incorporating a pressure sensor 1 and a control device 101. The control device 101 is a monitor equipped with a microcomputer, which can be connected to the connector terminal 41 of the connection terminal portion 4 of the pressure sensor 1. The microcomputer includes a display unit, a central processing unit (CPU) including a calculation unit and a control unit, a read-only memory (ROM) and a random access memory (RAM) as a storage unit, and an input-output control unit. Therefore, by connecting the pressure sensor 1 to the control device 101, the blood pressure in the coronary artery in the body cavity can be measured and the living body information can be displayed.

[0079] In addition, a Universal Serial Bus (USB) terminal may be provided as the connector terminal. In this case, by connecting the USB terminal to the control device 101, detection information obtained from the output of the pressure sensor 1 can be displayed.

[0080] Figure 6 The structure of the system 100a in which the pressure sensor 1 is connected to the control device 101a connected to the pressure sensor 1 via a wireless circuit is shown. The control device 101a is provided with a wireless transceiver, and the connection terminal portion 4a is provided with a wireless module or an internal battery. Therefore, the living body information can be wirelessly transmitted from the connection terminal portion 4a to the control device 101a, and the living body information can be displayed on the control device 101a.

[0081] Therefore, by wirelessly connecting the pressure sensor 1 and the control device 101a, there is an advantage that wires and the like do not become obstacles when measuring blood pressure, and the operation becomes easy.

[0082] As described above, according to the present embodiment, it is possible to provide the pressure sensor 1 which is compact, has insulation properties ensured, and has high reliability.

[0083] In addition, the pressure sensor of the present invention is suitable for measuring the blood pressure of the human body, and can also be used for pressure management during diagnosis or treatment of the brain, kidney, bladder, abdominal cavity, uterus, esophagus and stomach. Moreover, the pressure sensor of the present invention is suitable for use in catheters (guidewires), but is not limited to this. It can also be applied to other medical machines. Furthermore, it is not limited to the field of medical machines, but it can also be applied to machines and devices that include pressure sensors and need to be miniaturized.

[0084] The present invention is not limited to the structure of the embodiment described above, and various modifications can be made without departing from the scope of the invention. Moreover, the embodiment described above is provided as an example, but is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made. These embodiments or their modifications are included in the scope or spirit of the invention, and are also included in the invention described in the claims and their equivalents.

Claims

1. A pressure sensor, characterized in that: include: Sensor body; A pressure sensor element is disposed on one side of the sensor body; a through hole formed from one side of the sensor body to the other side, through which a wire connected to the pressure sensor element for supplying power passes; and an insulating layer formed on the inner wall of the through hole, The conductor core wire portion of the wire comprises: an insulated conductor core portion covered by an insulating coating; and a bare conductor core portion not covered by the insulating coating, Only the bare conductor core part of the wire core part passes through the through hole and is electrically connected to the pressure sensor element via an electrode containing solder, The electrode enters the through hole to form an intrusion portion, which covers the portion of the insulating layer close to the one side, and the bare conductor core wire portion contacts and connects the intrusion portion in the through hole, and forms a gap between the electrode and the inner wall of the through hole.

2. The pressure sensor according to claim 1, characterized in that: At least two through holes are formed.

3. The pressure sensor according to claim 2, characterized in that: The electrode is a low melting point metal.

4. The pressure sensor according to claim 1, characterized in that: The leading end portion of the conductor core portion passing through the through hole is linear.

5. The pressure sensor according to claim 1, characterized in that: The conductor core wire of the wire is formed of a copper-silver alloy wire.

6. The pressure sensor according to claim 1 or 2, characterized in that: An electrode layer is formed to extend around one surface side of the through hole and on an inner wall side of the through hole.

7. The pressure sensor according to claim 1 or 2, characterized in that: The outer surface of the sensor body is covered with insulation.

8. The pressure sensor according to claim 7, characterized in that: The insulating coating is flexible.

9. The pressure sensor according to claim 7, characterized in that: For the insulating coating, a material having living body compatibility is used.

10. The pressure sensor according to claim 1 or 2, characterized in that: The sensor bodies are bridge-connected to form a bridge circuit.

11. The pressure sensor according to claim 10, characterized in that: An amplifier is connected to the output end of the bridge circuit.

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