JPS6249827A - Production of optical fiber catheter pressure-sensitive part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a pressure sensitive part of an optical fiber catheter, and in particular to a pressure sensitive part of an optical fiber catheter having a structure suitable for eliminating drift due to moisture absorption of a pressure receiving plate. Relating to a manufacturing method.

[Prior Art and its Problems] FIGS. 1 to 3 are longitudinal cross-sectional views of a pressure sensitive part of a catheter tip type blood pressure transducer using a conventional optical fiber. In FIG. 1, an optical fiber bundle 9 inserted into a cylindrical body 8 is housed in the cylindrical body 2, and a light-reflecting pressure plate 1 is fixed to the tip with an adhesive 3 and hermetically sealed. When the pressure applied to the pressure plate 1 increases, the pressure plate 1 curves, and the distance between the end face of the optical fiber bundle 9 and the pressure plate 1 becomes smaller, the reflection is reflected by the pressure plate 1 and passes through the optical fiber bundle on the receiver side. The amount of light decreases. If the distance between the pressure receiving plate 1 and the fiber bundle 9 is determined so that this changes approximately linearly, accurate intracardiac pressure can be measured.

Now, the pressure receiving plate 1 is mainly made of stainless steel from a hygienic and industrial standpoint, and its thickness is approximately 10 to 20 μm depending on the outer diameter (approximately 2IIIF1), processing method, pressure deflection characteristics, etc. The deflection due to the pressure difference on both sides of the pressure plate 1 is 2
00mH (The difference in J is 5μmP￥ degree, for example, 1 shoe H
In order to ensure the accuracy of g, it becomes necessary to control the deflection of the pressure receiving plate 1 of 0.25 μm. 2 and 3 show that the pressure receiving plate 1 is sandwiched between an outer cylindrical body 4 and an inner cylindrical body 5 and an adhesive 3 is applied to prevent the pressure receiving plate 1 from falling off.
Alternatively, it is fixed with a sealing material 6 to maintain airtightness.

However, in this case, when the adhesive 3 and sealing material 6 applied to the clamping surfaces of the pressure plate 1 absorb moisture and swell, a phenomenon occurs in which the pressure plate 1 bends. Also, in order to insert it into the body, 37
When the temperature rises to around °C, the pressure receiving plate 1 also expands and bends. As mentioned above, 0.25 μm/IIrIIriH (
If it has a deflection characteristic of J, for example, moisture absorption of 1 μm,
If there is a temperature-dependent deflection characteristic, it is actually 4C)sHQ.
error, making it impractical. It is difficult to completely apply the adhesive inside a cylindrical body with an outer diameter of approximately 21M1, and if uneven application occurs on the circumference of the pressure receiving plate 1, moisture may enter between the pressure receiving plate and the optical fiber bundle. , which can significantly change the light level and cause drift. In FIG. 3, the area where the outer cylindrical body 4 and the pressure receiving plate 1 come into contact is usually machined (for example, by lathe processing) to ensure perpendicularity and flatness.
At the current Canadian level, it is difficult to process with a gap of less than 5μ, and the yield when processing parts is poor. According to experiments, the gap between the pressure receiving plate 1, the outer cylindrical body 4, and the inner cylindrical body 5 is 2.
~3μm, the hysteresis characteristic during processing and depressurization is 1
It is as large as 0 to 20 sHq, and errors occur in waveform observation during intracardiac pressure measurement, making accurate data collection difficult.

[Object of the Invention] The present invention eliminates the drawbacks of the prior art described above, and provides an optical fiber catheter pressure-sensitive section that is not affected by moisture absorption or temperature, has less variation in detection characteristics, and is excellent in mass production. The purpose is to provide a method.

[Summary of the Invention] That is, the gist of the present invention is to provide a pressure-sensitive portion of an optical fiber catheter having a pressure-receiving plate airtightly attached to the distal end thereof, which is a cylindrical body having a clamping surface in which the inner diameter portion is more protruded in the longitudinal direction than the outer diameter portion. It is characterized in that the pressure receiving plate is held from both sides and the cylindrical body and the outer peripheral surface of the pressure receiving plate are welded.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 4 and 5.

FIG. 4 is an explanatory diagram of a method of manufacturing an optical fiber catheter pressure-sensitive section according to an embodiment of the present invention, and FIG. 5 is a partially enlarged view thereof. The pressure receiving plate 1 includes a metal pipe 2 having a tapered clamping surface such that the outer diameter part is shorter than the inner diameter part by δ (1 to 5 μm) in the longitudinal direction, and a ring 1 having a similar clamping surface.
0, these pressure receiving plate 1, metal pipe 2, ring 1
The blank joint part 13 of 0 is welded using a laser such as COz or YAG or an electron beam 11.12. At this time, pressure receiving plate 1,
The metal pipe 2 and ring 10 are pressurized in the thrust direction to reduce deviation and eccentricity during rotation, and are surrounded by a dry box 16, and welding is performed while heating the inside of the dry box 16 with a heater 17. Moreover, if the inside of the dry box 16 is shielded with an inert gas such as argon, helium, or nitrogen during welding, oxidation of the welded portion can be prevented.

In the enlarged view of FIG. 5, a metal pipe 2 has a tapered clamping surface in which the outer diameter part is shorter than the inner diameter part by δ (1 to 5 μm) in the longitudinal direction, and a ring 10 has a similar clamping surface. The pressure receiving plate 1 is held and pressurized in the axial direction. As a result, the pressure receiving plate 1 has complete sandwiching surfaces 14 and 15, and by welding with a laser or electron beam, the metal pipe 2, pressure receiving plate 1, and ring 10 are completely fused on the circumference, and a sufficient Airtightness is obtained, and the pressure receiving plate 1 does not bend due to moisture absorption, temperature changes, etc. Further, since the deformation of the pressure receiving plate 1 during pressurization and depressurization occurs with reference to the complete clamping surfaces -14, 15, the hysteresis characteristic at the zero point midpoint is also greatly improved.

A receiver for the welding part 13 during laser or electron beam welding,
The energy generated rises to the metal melting temperature, and since the pressure receiving plate 13 is very thin at 5 to 20 μm, it is easily thermally deformed. To prevent this, the laser beam diameter is narrowed down as much as possible.
It is also necessary to use the minimum amount of energy. However, if the energy is reduced, the strength of the welded portion 13 will decrease, and there is a risk that a serious defect such as separation of the pressure receiving plate 1 and the ring 10 will occur. Experiments have shown that by preheating the welded part, a high-strength weld can be obtained with less energy.
This time, good results were obtained by preheating to 70 to 300'C (more than 300'C causes brittleness) and welding in a high temperature atmosphere. In addition, in a high-temperature atmosphere, the pressure plate 1 may elongate at high temperatures, and if it bends slightly or is returned to the chamber base after welding, the pressure plate 1 will bend due to the difference in heat capacity between the metal pipe, the ring 10, and the pressure plate 1. A pressure sensitive part that is stretched in the outer circumferential direction and has good linear characteristics and hysteresis characteristics can be obtained.

[Effects of the Invention] As explained above, according to the present invention, when sandwiching the saucer plate, no adhesive resin or the like is used to protect the airtightness, and the process is completed only by welding, which is affected by moisture absorption and temperature. Hysteresis characteristics during pressurization and depressurization are also significantly improved. Further, since the component parts of the present invention can be easily obtained by ordinary processing methods such as lathe processing and wire cutting, visual inspection is easy, and welding can be performed in a short time, making it a processing method that facilitates mass production. When welding, by placing the workpiece in an atmosphere that is higher than room temperature and preheating it, it is possible to form a strong welded part by 1q with less energy.

[Brief explanation of the drawing]

1 to 3 are longitudinal cross-sectional views of a conventional optical fiber catheter pressure sensitive section, FIG. 4 is an explanatory diagram of a method for manufacturing the optical fiber catheter pressure sensitive section according to the present invention, and FIG. 5 is a part thereof. This is an enlarged view. 1: Pressure plate, 2: Metal pipe, 10: Ring, 16: Dry box. Agent Patent attorney Sato Fujio 1 Figure o 2 Mouth break 3r21 → 4 Figure r Oral procedure amendment (White 56\○,'; 2.24 Showa year)
May 11th, 1st Edition Director General, 1st matter (1 Indication 1985 Patent Application No. 190680)
Bow 2 Name of the invention 9] I. Ibakaartel Pressure-sensitive part manufacturing method 3 What is the relationship between corrections 1) Mi 1 Applicant Address 1 Marunouchi 2-chome, Chiyoguchi 1-ku, Tokyo?
No. 62 name fF (512) IX:, 1 standing f'
Ui*”5J4”SL+j:'S-kai? =1, -1, 1-1, (・i'1., '2 ro 5, Amendment pair 9 Detailed explanation column of the invention in the specification. 6. Contents of the amendment (1) Specification number 2nd page 1971st r0.25μm1 I
Corrected to "Q, 025 μm". (2) Specification page 3, line 9 r0.25μm/1mHQ
'Correct J to rO, 025μm/1mmHQJ. that's all

Claims (2)

[Claims] (1) In an optical fiber catheter pressure-sensitive section having a pressure-receiving plate airtightly attached to the distal end, the pressure-receiving plate is held from both sides by a cylindrical body having a clamping surface in which the inner diameter part protrudes in the longitudinal direction than the outer diameter part, and the pressure-receiving plate is held from both sides. A method for manufacturing a pressure sensing part of an optical fiber catheter, characterized by welding the outer peripheral surface of the body and the pressure sensing plate. (2) The manufacturing method according to claim 1, wherein during the welding, the outer peripheral surfaces of the cylinder and the pressure receiving plate are welded in an atmosphere at a temperature higher than room temperature.