JPS61288828A - Converter for internal pressure of living body - 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 [Field of Industrial Application] The present invention relates to an in-vivo pressure transducer that can measure the absolute amount of pressure with extremely high reliability even when used for a long time.

[Prior art]

Accurate monitoring of volume is required. This measurement method includes a method in which a pressure transducer is installed outside the living body, and the pressure inside the living body is transmitted to the transducer by connecting the monitored area and the transducer with a medium such as physiological saline; 2 and 3 are diagrams showing examples of conventional in-vivo pressure transducers using the latter method, in which (a) is a top view, and (a) is a top view; (b) is a side sectional view. FIG. 2 shows an example in which a strain gauge or a semiconductor piezo element is used as a pressure-sensitive element, and the pressure-receiving plate 1 is connected to the fixed layer 2.
The displacement of the pressure-receiving plate, which is fixed to the casing 3 at its periphery through the in-vivo pressure 10, is controlled by the pressure-sensitive element via the connecting rod 4 whose one end is fixed to the pressure-receiving plate and the other end is fixed to the support part 6. The amount of electricity transmitted to the pressure sensitive element 5 and converted by the pressure sensitive element 5 is
It is led out of the living body by a cord 9 having a built-in signal line 7 connected to the casing and a guide tube 8 for releasing the internal pressure of the casing to atmospheric pressure. Furthermore, FIG. 3 shows an example in which a piezoelectric element is used as a pressure-sensitive element, and similarly to FIG. The displacement of the pressure-receiving plate 1 is directly transmitted to the pressure-sensitive element 5, and the amount of electricity converted by the pressure-sensitive element is led outside the living body by a cord 9 that has a built-in signal line 7 connected to the pressure-sensitive element 5. It's something to be attracted to. Note that in order to maintain the mechanical strength of the transducer and accurately respond to rapid changes in pressure, the housing 3 and the pressure receiving plate 1 are usually made of metal.

゛ In either case, the transducer is directly implanted in the body to be monitored, so it is important that such a transducer is small enough to be easily inserted into the body. It is. - Also, in order to improve the sensitivity of the transducer, it is necessary to apply as large a displacement as possible to the pressure-sensitive element, and it is desirable to select a shape and material for the pressure-receiving plate that has as little rigidity as possible against the internal pressure of the body. For this reason, the pressure-receiving plate must have a thickness of 5 to several tens of μm and an area the size of several pieces of steel.In order to fix such a pressure-receiving plate to the housing, organic or inorganic adhesives are required from the viewpoint of workability. Many drugs were used.

However, when such a transducer is implanted in a living body, it may be affected by humidity in the living body, displacement of the pressure plate due to swelling of the adhesive due to blood or body fluids, or changes in humidity within the housing due to moisture permeation of the adhesive. However, there is a drawback that the reference point of the converter's electrical quantity equivalent to atmospheric pressure, the so-called zero point, gradually changes, making it impossible to accurately measure the absolute value of the internal pressure, and improvements are desired.

[Purpose of the invention]

In view of the current state of pressure transducers for implantation in living bodies, the present invention was completed as a result of various studies on fixing methods for the pressure receiving plate and the housing. The present invention also aims to provide a transducer that can accurately measure pressure without changing its zero point.

[Structure of the invention]

That is, the present invention relates to a pressure transducer for implantation in a living body, in which a pressure-receiving plate is disposed on at least one side of a casing containing a pressure-sensitive element, which converts the detected pressure into a displacement amount, and This in-vivo pressure transducer is characterized in that the pressure receiving plate is fixed to a housing by welding in a pressure transducer that transmits the displacement amount to a pressure sensitive element and converts it into an electrical quantity.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a sectional view of an in-vivo pressure transducer according to an embodiment of the present invention.
1 is a pressure receiving plate, 3 is a housing, 4 is a connecting rod, 5 is a pressure sensitive element, 6
1 is a support part of the connecting rod, 7 is a signal line, 8 is a guide tube, 9 is a cord, and 11 is a welded part. Pressure receiving plate 1 and housing 3
are made of metal materials, such as stainless steel, phosphor bronze, chili radium, gold, and silver.
It can be mentioned as a material suitable for quality and processing, but
The pressure receiving plate 1 and the housing 3 do not need to be made of the same material.

The pressure receiving plate 1 is installed in the pressure receiving opening of the casing 3, and only the periphery thereof is fixed by welding. As a means of welding, irradiation with a laser beam, an electron beam, etc. is used. The optimum irradiation conditions are selected depending on the material, thickness, etc. of the housing 3 and the pressure plate 1, but if the irradiation energy is too large, not only will the flatness of the welded part become poor, but also the pressure plate 1 may melt and come off. Furthermore, if the irradiation energy 1 is too small, even if welding is uniform in appearance, the depth of the weld between the pressure plate 1 and the housing 3 will be shallow, and the pressure plate 1 may peel off during use. In addition, in welding, a different type of welding metal material having good affinity for both may be interposed at the welding portion between the pressure receiving plate 1 and the housing 3.

The pressure sensitive element 5 may be a strain gauge, a semiconductor piezo element, a piezoelectric element, or the like, and the type thereof is not specified at all, and there is no limit to the number of the elements to be connected. Further, the connecting rod 4 is not necessarily required, and these pressure sensitive elements 5 may be directly fixed to the inside of the casing of the pressure receiving plate 1 using a suitable adhesive. After welding, the casing 3 and pressure plate 1 are sealed using an appropriate organic resin, taking into account the compatibility of the internal pressure transducer with the living body, reducing resistance during insertion, and protecting the pressure plate 1. It is okay to coat the surface.

〔Effect of the invention〕

By fixing the pressure receiving plate and the housing by welding, the in-vivo pressure transducer according to the present invention can prevent moisture, blood, body fluids, etc. from entering any part of the transducer. The problem of measurement errors caused by displacement of the pressure receiving plate due to K such as swelling of the fixed layer, moisture absorption, and moisture permeation, or changes in the zero point due to changes in humidity inside the housing, which were disadvantages of the previous model, can be improved. Extremely reliable measurement values can be obtained even when implanted in a living body.

〔Example〕

A semiconductor piezo element is used as the pressure-sensitive element, stainless steel is used as the material of the pressure-receiving plate and the housing, and the thickness of the pressure-receiving plate is 1.
In the biological pressure transducer having the structure shown in Fig. 1 of 0#I,
As a comparative example, silicon oxide powder (
49 parts) as additives, bisphenol A type epoxy In (10(1)) and trimellitic anhydride (64 parts).
A transducer case bonded with a mixed resin consisting of the following was fabricated, and a transducer (2) was fixed by electron beam irradiation as an example of the present invention.

The zero points were calibrated in distilled water at 37° C. (underwater pressure 10 μH20), and the temporal changes in the zero points under this condition were recorded. Table 1 shows the results. As can be seen from Table 1, in vivo pressure transducer B, in which the pressure receiving plate and the housing were fixed by electron beam irradiation, was able to significantly improve the change in zero point compared to transducer A, which was fixed with adhesive.

Chapter 1 Table (Unit: mHg)

[Brief explanation of drawings]

FIG. 1 is a sectional view of an internal pressure transducer according to an embodiment of the present invention, in which (a) is a front sectional view and (a) is a side sectional view. FIGS. 2 and 3 are diagrams showing an example of a conventional internal pressure transducer, in which (a) is a top view and (a) is a side sectional view.

Claims (2)

[Claims] (1) On at least one side of the casing containing the pressure-sensitive element,
A pressure receiving plate is arranged to convert the detected pressure into a displacement amount,
An in-vivo pressure transducer for transmitting the amount of displacement to a pressure sensing element and converting it into an amount of electricity, characterized in that the pressure receiving plate is fixed to a housing by welding. (2) The in-vivo pressure transducer according to claim 1, wherein electron beam welding or laser beam welding is used as the welding means.