JPH08247873A - Pressure sensor - Google Patents

Abstract

PURPOSE: To simplify actual packaging to a capillary, and thereby enhance operating performance by letting the back face side of a sensor tip be so constituted that a back pressure port is provided for keeping the aforesaid side at atmospheric pressure. CONSTITUTION: A detecting window section 11a is formed at the tip end section of a cathetel 11. A sensor tip 13 joined to a silicone pedestal 12 by anode joining is disposed at the inside of the detecting window section 11a. The diaphragm 13a of the sensor tip 13 is provided for a place faced to the detecting window section 11a. A groove section 12a communicated with a space section A at the back face side of the diaphragm 13a of the sensor tip 13, is formed at the silicone pedestal 12 by etching and the like, and the groove is formed into a back pressure port 15 in a bonded condition. Since the back pressure port 15 is released to atmospheric pressure through the inside of the cathetel 11, it is prevented from being adversely affected by temperature and the like when pressure is measured by the sensor tip 13. Adhesives 14 are also prevented from going around the back pressure port 15 side when the adhesives 14 are filled in at the time of assembly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention arranges a sensor chip inside a detection window formed at the tip of a thin tube via a pedestal and converts the pressure received by the diaphragm of the sensor chip into an electric signal. The present invention relates to a pressure sensor adapted to output as an output.

[0002]

2. Description of the Related Art As a pressure sensor of this type, for example,
There is one as shown in FIG. That is, this one is
For example, a detection window 1a is formed at the tip of a catheter 1 that can be inserted into an affected area to detect pressure such as blood pressure during inspection of circulatory function disease, and the pressure received by the detection window 1a is detected. It is a thing. Inside the catheter 1, a silicon-made sensor chip 2 is arranged via a pedestal 3 to convert a pressure signal into an electric signal corresponding to its size when pressure is applied to a portion corresponding to the detection window 1a. It is set up. The electrical signal of the sensor chip 3 is configured to be taken out to the outside by the lead wire 4 led to the proximal end side of the catheter 1.

The above-mentioned sensor chip 2 is provided with a diaphragm 2a formed in a thin film shape by etching or the like at a portion corresponding to the above-mentioned detection window 1a, and a bridge circuit by diffusion resistance is formed at this diaphragm 2a portion. . When the diaphragm 2a is displaced by the pressure received, the resistance value of the diffusion resistance changes according to the pressure received at that time, and a voltage signal according to the pressure can be obtained from the bridge circuit.

In this case, the diaphragm 2a of the sensor chip 2 is designed to be displaced by receiving pressure on the upper surface side, but when the space A on the lower surface side is hermetically closed, temperature fluctuations, etc. Due to the change in the pressure in the space portion A due to the above, the displacement cannot be accurately displaced in accordance with the pressure applied to the diaphragm 2a, and the accuracy of the detected pressure is lowered.

Therefore, conventionally, in order to maintain the pressure of the space portion A on the back side of the diaphragm 2a of the sensor chip 2 at the atmospheric pressure, a back pressure hole 4 penetrating to the lower surface side is provided at a corresponding portion of the pedestal 3. It is formed so as to communicate with the base end side of the catheter 1 through a gap between the bottom surface of the pedestal 3 and the inner wall of the catheter 1. As a result, the diaphragm 2a can be displaced according to the pressure received by the detection window portion 1a, and the pressure can be accurately detected.

[0006]

However, in the conventional structure as described above, when the sensor chip 2 is fixed to the pedestal 3 and fixed inside the catheter 1, the adhesive 5 is filled. Since it is performed, it is necessary to prevent the adhesive 5 from wrapping around the back pressure hole 4 on the bottom surface side of the pedestal 3, and performing such a work becomes a very troublesome work, and the assembling workability is poor. There is a problem that becomes.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a back pressure hole for maintaining the back side of the diaphragm of the sensor chip at atmospheric pressure, and to easily mount it on a thin tube. Another object of the present invention is to provide a pressure sensor capable of improving workability.

[0008]

According to the present invention, a sensor chip is arranged inside a detection window formed at the tip of a thin tube via a pedestal, and the pressure received by the diaphragm of this sensor chip is converted into an electric signal. It is intended for a pressure sensor that is converted and output, the space between the pedestal formed on the back side of the diaphragm of the sensor chip through the contact surface between the sensor chip and the pedestal. Is characterized in that a back pressure hole is formed so as to communicate with the base side of the thin tube (the invention of claim 1).

Further, the back pressure hole can be constituted by a groove portion formed in a contact surface portion of the pedestal with the sensor chip (the invention of claim 2).

Further, the back pressure hole may be constituted by a groove portion formed in a contact surface portion of the sensor chip with the pedestal (the invention of claim 3).

Further, a seat member may be interposed between the pedestal and the sensor chip, and the back pressure hole may be formed by a notch formed in the seat member (the invention of claim 4).

[0012]

According to the pressure sensor of the first aspect, since the back pressure hole is formed between the sensor chip and the base along the axial direction of the thin tube, the sensor fixed to the base. Even when the chip is mounted in the thin tube, even if the adhesive is filled, the adhesive does not wrap around the opening of the back pressure hole, and it is not necessary to assemble while paying attention to such wraparound. As a result, the assembling work can be easily performed, and the assembling workability can be improved.

According to the pressure sensor of the second aspect, a groove is formed in the pedestal in advance, and when the sensor chip is fixed, a space formed by the groove and the sensor chip is formed as a back pressure hole. It can be done easily and inexpensively.

According to the pressure sensor of the third aspect, the groove portion is formed in advance in the sensor chip, and the space book formed by the groove portion with the pedestal when the sensor chip is fixed is formed as the back pressure hole. Therefore, it is not necessary to process the pedestal, and it can be easily and inexpensively performed.

According to the pressure sensor of the fourth aspect, since the back pressure hole is formed by interposing the sheet having the cutout between the sensor chip and the pedestal, it is necessary to process the sensor chip and the pedestal. Can be easily assembled, and workability can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. In FIG. 1 showing the tip portion, a catheter 11 as a thin tube having a tube diameter (for example, about 1 mm) that can be inserted into an affected part of a human body has a detection window portion 11a formed at the tip portion. A silicon sensor chip 13 fixed to a silicon pedestal 12 is adhesively fixed inside the position corresponding to the detection window portion 11a of the catheter 11. In this case, the sensor chip 1
3 is an anodic bonding (Anodic B) which will be described later on the silicon pedestal 12.
It is fixed by adhesion so that it becomes one by
It is mounted by filling an adhesive agent 14 from the tip end portion of the catheter 11 inserted into the catheter 11.

The sensor chip 13 is formed with a diaphragm 13a which receives pressure, and the diaphragm 13 is formed.
A diffused resistor having a piezoresistive characteristic in which the resistance value changes when it is distorted by the applied pressure is formed in the portion a, and the electrode terminals are led out in a bridge connection state. The above-mentioned diaphragm 13a is a thin film formed by subjecting the silicon forming the sensor chip 13 to etching from the back side by anisotropic etching or the like, and a space A is formed on the back side of the diaphragm 13a. It will be in the formed state.

As shown in FIG. 2, the silicon pedestal 12 is made of silicon and has a block shape, and is formed in a size corresponding to the sensor chip 13. The silicon pedestal 12 is provided on the rear surface of the diaphragm 13a of the sensor chip 13. A groove portion 12 is formed along the proximal end side of the catheter 11 from a portion corresponding to the space portion A.
a is formed. When the sensor chip 13 is bonded by anodic bonding, the groove 12 of the silicon pedestal 12 is bonded.
The back pressure hole 15 is formed by a. To the electrode terminals of the sensor chip 13, a large number of lead wires for taking out signals formed on the flexible printed circuit board 16 inserted into the catheter 11 are electrically connected, respectively, and from the base end portion of the catheter 11. The detection signal can be obtained.

Further, the inside of the catheter 11 is hollow, and the back pressure hole 15 is held from the base end side through the inside of the catheter 11 so as to be equal to the atmospheric pressure. There is. As a result, the sensor chip 1
When the diaphragm 13a receives the pressure received from the detection window 11a of the catheter 11, the space 3 is always open to the atmospheric pressure, so that an accurate detection signal corresponding to the pressure can be output. Like

The above-mentioned anodic bonding is a general bonding method in which glass and silicon or metal are bonded by electrostatic force without using an adhesive. For example, the two are brought into contact with each other under high temperature and high voltage application. As a result, they are bonded by fusion due to the movement of glass ions at the interface. Further, such anodic bonding has advantages that distortion and thermal stress are smaller than solder bonding, high bonding strength is obtained, and further corrosion resistance is excellent.

According to the above structure, since the back pressure hole 15 is formed in the contact surface portion between the sensor chip 13 and the silicon pedestal 12, when the silicon pedestal 12 is mounted in the catheter 11, the adhesive back pressures. Since it does not go around the hole 15 and it is not necessary to pay attention to that, the assembly workability is improved.

Further, the sensor chip 13 is attached to the silicon pedestal 1
Since it is bonded to No. 2 by anodic bonding, it is not necessary to use an adhesive and the workability is improved, and the sensor chip can be diced while the silicon pedestal 12 and the sensor chip 13 are bonded. The assembly process can also be simplified. Further, since the silicon pedestal 12 is used as the pedestal, the same material as that of the sensor chip 13 has the same expansion coefficient so that it is not subjected to thermal distortion and an accurate detection operation can be performed.

FIGS. 3 and 4 show a second embodiment of the present invention. The difference from the first embodiment is that instead of forming the groove 12a in the silicon pedestal 12, the sensor chip 13 is prepared in advance. That is, the groove portion 17 is formed on the side.

That is, as shown in FIG. 4, on the back side of the sensor chip 13, a groove 17 is formed by a method such as alkali etching so as to communicate with the space A on the back side of the diaphragm 13a. , This allows
When the sensor chip 13 is bonded to the silicon pedestal 12 by anodic bonding, the back pressure hole 18 can be formed by the groove portion 17.

Therefore, according to this embodiment, the same effect as that of the first embodiment can be obtained, and when the diaphragm 13a of the sensor chip 13 is formed instead of separately etching the silicon pedestal 12. By adding the step of forming the groove portion 17 to the back pressure hole 1
8 can be formed.

5 and 6 show a third embodiment of the present invention. The difference from the first embodiment is that the resin as shown in FIG. 6 is provided between the silicon pedestal 12 and the sensor chip 13. The sheet member 19 made of metal is interposed. As shown in the drawing, the sheet member 19 has a cutout portion 20 formed along the lengthwise direction of the catheter 11 to have a substantially U-shape, and between the silicon pedestal 12 and the sensor chip 13. The cutout portion 20 functions as the back pressure hole 21 in the arranged state.

Therefore, also in the third embodiment, the same effect as in the first embodiment can be obtained, and it is sufficient to interpose the sheet member 19 separately prepared, so that the assembling workability is further improved. . Note that such a sheet member 19 may be made of resin, or may be made of metal or silicon.

FIG. 7 shows a fourth embodiment of the present invention. The difference from the first embodiment is that the sensor chip 13 is mounted on the porous catheter 22 instead of the catheter 11. . This porous catheter 22
Has, for example, two lumens (holes) 22a and 22b, which are separated by a partition wall 22c. A partition wall 22 is provided inside the distal end of the porous catheter 22.
A detection window portion 23 is formed in c.

The sensor chip 13 is bonded to the silicon pedestal 12 by anodic bonding, and the diaphragm 13a.
The portion is arranged inside the one lumen 22a so as to face the detection window portion 23, and the adhesive 24 is filled and fixed. The flexible printed board 16 is arranged in the same lumen 22a along the surface of the partition wall 22c. As a result, the back pressure hole 15 can be opened to the atmospheric pressure on the proximal end side of the porous catheter 22 via the lumen 22a.

According to the fourth embodiment as described above, even when the sensor chip 13 is mounted on the porous catheter 22, the back pressure hole 15 is formed between it and the silicon pedestal 12, so that the adhesive 24 Since it is not adversely affected by the wraparound, the assembly workability can be improved, and the back side of the sensor chip 13 can be protected and reinforced by the silicon pedestal 12.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. The sensor chip 13 may be adhesively fixed to the pedestal 12 with an adhesive. The sensor chip 13 may be other than the piezoresistive type. In order to connect to the electrode terminals of the sensor chip 13, a normal lead wire may be connected instead of the flexible printed board 16.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view and a vertical sectional front view of an essential part showing a first embodiment of the present invention.

FIG. 2 is an external perspective view of a pedestal

FIG. 3 is a diagram corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 4 is an external perspective view showing the back side of the sensor chip.

FIG. 5 is a diagram corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 6 is a plan view of the seat.

FIG. 7 is a view corresponding to FIG. 1 showing a fourth embodiment of the present invention.

FIG. 8 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

11 is a catheter (capillary tube), 11a is a detection window, 12
Is a silicon pedestal (base), 12a is a groove, 13 sensor chips, 13a is a diaphragm, 15 is a back pressure hole, 16 is a flexible printed circuit board, 17 is a groove, 18 is a back pressure hole,
19 is a sheet member, 20 is a notch, 21 is a back pressure hole, 22
Is a porous catheter, 22a and 22b are lumens, 22
c is a partition wall, 23 is a detection window, and 24 is an adhesive.

Claims (4)

[Claims] 1. A sensor chip is arranged inside a detection window formed at the tip of a thin tube via a pedestal, and the pressure received by the diaphragm of this sensor chip is converted into an electric signal and output. In the pressure sensor, a back pressure hole is formed so that the space between the pedestal formed on the back side of the diaphragm of the sensor chip and the pedestal is communicated with the base side of the thin tube via the contact surface between the sensor chip and the pedestal. A pressure sensor characterized by being formed. 2. The pressure sensor according to claim 1, wherein the back pressure hole is formed by a groove portion formed in a contact surface portion of the pedestal with the sensor chip. 3. The pressure sensor according to claim 1, wherein the back pressure hole is formed by a groove portion formed in a contact surface portion of the sensor chip with the pedestal. 4. A seat member is interposed between the pedestal and the sensor chip, and the back pressure hole is formed by a cutout portion formed in the seat member. Pressure sensor.