JPH0244724Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a chemical substance measuring device for measuring gas and electrolyte concentrations in body fluids such as blood.

(Conventional technology) Partial pressure of gases such as oxygen and carbon dioxide in blood, hydrogen,
The concentration of ions such as sodium, potassium, calcium, chlorine, etc. is extremely important as a measure of the respiratory and metabolic functions of living organisms. Conventionally, these measurements have been carried out using blood sampling and analysis devices, but there are problems such as the time it takes from blood sampling to completion of the measurement, the impossibility of continuous measurement, and the loss of blood from the patient. The dot was hot.

In order to solve these problems, the present applicant connected a cylindrical cell 5 to a catheter 4 inserted into a blood vessel 1, as shown in FIG. 4, and housed a sensor main body 6 within the cell. Cell and infusion bag 12
A suction means (roller pump) 1 for injecting the infusion into the patient through the cell and storing the infusion in the cell during measurement.
proposed a device that measures chemical substances in the blood by aspirating the infusion fluid in the cell 5 using No. 1, then suctioning the patient's blood from the catheter 4, and bringing the blood into contact with the sensor. (Unexamined Japanese Patent Publication No. 55-76639) (Problem to be solved by the present invention) In this measurement method, the sensor is exposed alternately to infusion fluid and blood, so the next measurement may be started before a complete equilibrium state is reached. become. Therefore, the response speed of the sensor has a large effect on the measured value. For example, if the response speed of the sensor is slow, the next measurement will start before the change in sensor output is sufficient, and the difference in output between infusion and blood will become smaller.

In particular, since the amount of change in substance concentration in living organisms is small, it is absolutely necessary to avoid using sensors with slow response speeds. For this reason, in the infusion-based measurement method, a sensor with a high response speed and stable sensitivity and response speed is used. However, even when such a sensor is used, there is a problem in that the response speed may change and the measured values may vary.

(Means and effects for solving the problem) As a result of examining the causes of the above-mentioned response variations, the present inventors found that the cause was that the sensor body changed within the cell, and the sensor body changed the infusion flow path within the cell. It was found that the state of liquid replacement changes in order to cause the deformation. In particular, if the sensitive part of the sensor comes into contact with the inner wall of the cell, the liquid replacement will be poor and the response will be small. Since the size of the sensor body and cell are very small, slight distortion during the fabrication of the sensor body will cause such distortion and cause variations in response. However, it is difficult to completely prevent deformation of the sensor body.

The present inventors solved this problem by making the cross section of the sensor body an irregularly shaped cross section. In other words, the present invention is a sensor in which a sensor is embedded and fixed at the tip of a polygonal column-shaped resin molding, the sensitive part is made to protrude from the tip of the resin molding, and the lead wire is embedded in the resin molding and extends. a main body; a cylindrical cell having an opening for injecting liquid into a side wall; the sensor main body is accommodated so that each corner of the polygonal columnar resin molding is substantially inscribed therein; and the resin molding. This chemical substance measuring device comprises a connector fluid-tightly attached to the end of the cylindrical cell, to which a lead wire embedded and extending is connected.

(Example) Next, an example of the chemical substance measuring device of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the device of the present invention, which is composed of a sensor body 6, a cylindrical cell 5, and a connector 8.

Sensors 2 and 2' are embedded in the sensor body 6 with a sensing portion 9 protruding from the tip of a polygonal columnar resin molding 7. The lead wire 13 connected to this sensor is embedded in the resin molded product 7 and is taken out from the other end.

The sensor embedded in the resin molded product 7 has an elongated shape and has a sensing portion 3 at one end.
For example, there are Clark-type oxygen sensors, sensors for ions, gases, enzymes, etc. using FETs (field-effect transistors), coated wire-type electrodes, etc., and Clark-type oxygen sensors and FET sensors are particularly suitable. Further, in the case of an ion sensor, a comparison electrode 3 is also required.

After the sensors 2, 2' and the comparison electrode 3 are bundled, they are embedded in a columnar resin 7 having an irregular cross section with the sensitive portion of each sensor protruding. The resin to be molded into the polygonal column shape is preferably one with high rigidity, and one that dissolves oxygen or carbon dioxide is not preferable. Usually, epoxy resin, urethane resin, polyester resin, acrylic resin, etc. are used.
Among them, epoxy resin is particularly preferably used.

Sensors 2, 2' and reference electrode 3 are molded in resin 7.
The embedding can be done by extruding or potting the resin using a polygonal mold.

In addition, the sensitive part 9 of the sensor must protrude from the tip of the resin molded article 7, but if the length of this protrusion is too long, the protruding part will be deformed and cause errors, and if it is too short, the liquid replacement will be poor and the sensor will be damaged. Response becomes slow. It is usually appropriate to project a length of 2 to 10 mm. The cross-section of the resin molded product 7 is not particularly limited as long as it is triangular or more, but in order to ensure a flow path for infusion and blood, the cross-sectional area should be 80% or less of the internal cross-sectional area of the cell described later. Preferably, the shape is free of sharp indentations to prevent stagnation. If the resin molded body 7 has a polygonal cross-section at least at the tip end of the sensor body 6, the movement of the sensing part within the cell will be restricted.

The cylindrical cell 5 has an opening 14 in its side wall for injecting an infusion solution. The above-mentioned sensor main body 6 is housed within this cell 5. The inner diameter of the cell is shown in Figure 2 a, b,
As shown in c, each corner of the polygonal column-shaped resin molding 7 forming the sensor body must be large enough to be substantially inscribed in the inner wall of the cell. Substantially inscribed means that when the sensor body 6 is accommodated in the cell 5, the tip of the sensor body is unevenly distributed within the cell, causing the sensor 2,
2' and the sensitive part 9 of the comparison electrode 3 do not contact the inner wall of the cell, and the gap between the corner of the sensor body and the inner wall of the cell is usually 0.25 mm or less.

A connector 8 is attached to the end of the cell 5, and a lead wire 13 taken out from the other end of the sensor body 6 housed in the cell is connected to the connector pin 15. Inside the connector 8 is an electrically insulating resin 1 for holding the connection between the lead wire and the connector pin.
6 is filled. Additionally, O-rings 1 are attached to the ends of the cell 5 and the sensor body 6 to prevent leakage of liquid within the cell.
7 is provided. A screw member 18 is attached to the tip of the cell 5, and the screw member connects the cell to the catheter 4 in a fluid-tight manner as shown in FIG.

(Function) The sensor main body 6 housed in the cell 5 has its end connected to the connector 8, and the connector 8 and the cell 5 are connected with a screw so that their relative positions do not change. However, no matter how rigid the sensor body is made, the diameter of the sensor body is, for example, 2 to 5 mm.
Because it is very thin, a slight external force (for example, blood flow or thermal strain during autoclave sterilization) causes the axis to shift as shown in FIG. 3, causing the tip of the sensor 2 to come into contact with the inner wall of the cell 5.

In the present invention, by using a polygonal resin molding 7, a gap is formed between the sensor body and the inner wall of the cell when the sensor body is housed in the cell, thereby ensuring an infusion or blood flow path with a constant flow path cross section at all times. can do.

(Effects of the invention) As described above, in the chemical substance measuring device of the invention, by embedding the sensor in a polygonal columnar resin molding, the gap formed between the sensor body and the inner wall of the cell can be kept constant. A chemical substance measuring device with stable response speed can be provided.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the device of the present invention, FIG. 2 is a cross-sectional view of the tip of the device of the present invention, FIG. 3 is a longitudinal cross-sectional view of the tip of the conventional device, and FIG. 1 is a partial cross-sectional view showing an example of use of an infusion type chemical substance measuring device. 2, 2'...sensor, 3...comparison electrode, 4...
catheter, 5... cylindrical cell, 6... sensor body, 7... resin composition, 8... connector, 9...
Sensing part, 13...Lead wire.

Claims (1)

[Scope of utility model registration request] A sensor body is provided, in which a sensor is embedded and fixed in the tip of a resin molded product formed in the shape of a polygonal column, a sensing portion of the sensor is made to protrude from the tip of the resin molded product, and a lead wire is embedded in the resin molded product and extends; A sensor body is housed in a polygonal columnar resin molding such that each corner thereof is substantially inscribed therein, and a cylindrical cell having an opening for injecting a ring fluid in a side wall; A chemical substance measuring device comprising a connector liquid-tightly attached to an end of the cylindrical cell to which a lead wire is connected.