JPS62137560A - Sensor body - Google Patents

Abstract

PURPOSE:To keep electrolytic liquid or the like from permeating into an electrode body, by a method wherein one of two electrode bodies is mainly composed of carbon and a water insoluble substance is added thereto. CONSTITUTION:An oxygen electrode 1 as base electrode is made up of, for example, an anode 2 made of silver/silver chloride, a cathode 3 comprising a carbon rod mainly composed of carbon and additionally containing water insoluble substance (e.g. fat), an electrolytic liquid 4, a cylinder 5 and oxygen permeating fluorine based high polymer film 6. Then, a sensitive film 7 converting the outside of the film 6 and a semi-permeable film 9 are sealed up with a seal material 8. This facilitate the making of the cathode 3 while inhibiting permeation of a electrolytic liquid or the like into cathode 3 thereby enabling analysis with a high accuracy for long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sensor body for detecting components in liquids such as blood, urine, and aqueous solutions.

[Technical background of the invention and its problems]

In addition to ion selectivity', sensor bodies such as enzyme polarization and microorganism electroluminescence have the feature of being able to selectively measure the concentration of components in liquid □, making it more suitable for water analysis and blood analysis than ever before.

It has been used in a wide range of fields such as urine analysis and reaction control IA1. These sensor bodies can measure the yield of specific components in the sample liquid with high precision by simply immersing them in the measurement liquid, so various measuring devices using these sensors have been proposed. has been done.

If you can use it, it's the basics for measuring crucose in a sample solution!
A sensor body is known that uses oxygen or hydrogen peroxide quadrupole as its base and has a sensor body whose sensitive part is covered with a sensitive membrane on which glucose oxidase is immobilized. At this time, glucose in the sample solution reacts under the specific action of the enzyme during the process of diffusing through the enzyme carrier layer, resulting in the following formula: % Formula % D-//L/Coneau σ-lactone + H, Q →As shown by gluconic acid, oxygen in the liquid is consumed and hydrogen peroxide is produced. Using this reaction, the consumption of oxygen can be detected at the J station where the basic electric power is oxygen electrode.

Further, when hydrogen peroxide is used as the electrode, the amount of hydrogen peroxide produced is detected. Since there is a correlation between the output of the basic electrode obtained in this way and the glucose concentration in the sample liquid, it is possible to measure the glucose concentration in the sample liquid by measuring the output of the basic electrode. can.

On the other hand, the biochemically active substances used in this way are also selected from a wide variety depending on the component to be detected. For example, redox enzymes such as glucose oxidase, tacalase, urate oxidase, peroxidase, cytochrome oxidase, ascorbate oxidase, amino acid oxidase, cholesterol oxidase,
Pseudomonas fluorescens
, nitrifying bacteria, Bacillus 5ubtiJis.

Escherichia coli and other microbial cells and cells.

Examples include organelles, antibodies, antigens, binding proteins such as avidin, hormone II receptors, and lectins.

For immobilization of the above biochemically active substances, conventional physical adsorption methods,
Encyclopedia removal, chemical bonding methods, etc. can be used, and the sensor body is constructed by combining with a polarographic type material, etc., in the form of nine film-like particles or supported on the inner wall surface of a tube.

However, in the process of repeatedly analyzing components in various sample solutions using the above-mentioned sesser bodies, the biochemically active substances were gradually immobilized. , a low activation F of the sensitive part such as a membrane-like sensitive part and a deterioration of the performance of the polarographic electrode will eventually come to an end and the sensor body will need to be replaced. That is, in the conventional polarographic electrode, the material of the electrode body forming the polarographic electrode is Wt.
platinum.

Noble metals such as gold and rhodium are used, and when an electrode body using such an electrode body is used to analyze a sample, its surface gradually gets dirty, resulting in a decrease in sensitivity and an increase in noise. Easily disposing of the entire structure that has deteriorated in this way poses a problem in terms of resource conservation and is also uneconomical. Therefore, the biochemically active substance was immobilized using the electrode body. Attempts have been made to replace only the carrier, such as a sensitive membrane, and use it repeatedly, but since the replacement of the carrier requires constant adhesion with the polarographic electrode, it is difficult to reproduce the carrier with the same characteristics. Very hard to get mature Iia
There were also problems in that it required % and the operation was complicated.

In order to solve these problems, the present inventor has already filed an application for a sensor body in which the electrode body is made of a material containing carbon as a main component. (Japanese Patent Application No. 60-61831) By using such a material in which carbon is the main component, the sensor body can be manufactured more easily and at a lower cost than when conventional precious metals are used. Furthermore, H generated when measuring glucose using glucose oxidase, etc.
! 0! However, by using RN mainly composed of carbon, it is not directly decomposed on the surface and does not produce an O phenomenon, so it is difficult to measure the percentage.
A drop in v1 degree is prevented, and furthermore, the ML pole is long-lived because there is no [(lot left).Also, since it is electrochemically stable, for example, if the voltage is applied in the opposite direction by mistake, However, in the case of electrodes whose main component is carbon, no problem occurs.Furthermore, no dirt is observed to adhere to the electrode surface, preventing the reduction in sensitivity that conventionally occurs due to such adhesion. I was able to do that.

However, in an electrode body made of a material mainly composed of carbon, the electrolyte may penetrate due to its structure, and when such penetration occurs, a short circuit occurs and the sensor body loses its role. There remained the problem that the hair would no longer be exposed.

[Purpose of the invention]

The present invention has been made to address these problems, and it is an object of the present invention to provide a sensor body that is easy to manufacture, inexpensive, and has sufficient accuracy and service life.

[Summary of the invention]

The sensor body of the present invention is characterized in that one of the two electrode bodies of the polarographic electrode, which is the basic electrode of the sensor body, has carbon as a main component and contains a water-insoluble substance. It is said that

In accordance with the present invention, a simulated sectional view showing one row of such sensor bodies is shown in FIG. In the figure, the basic electrode in the case of one example is oxygen, and the anode 2 is made of % silver/silver chloride. Cathode consisting of a carbon rod containing carbon as a main component and a water-insoluble substance 3. 'f pole body I of these anodes and cathodes
'Bff, an electrolytic solution 4 made of, for example, a saturated KCit solution, an insulating cylindrical body 5 containing these, and an #R element provided in close contact with the lower end surface of the cathode 3 and the cylindrical body 5. It is composed of a transparent fluorine-based polymer @6. And the outside of this fluoropolymer film 6
Sensitive membrane 7 and semi-permeable which cover l and immobilize biochemically active substances! 9 is installed and the sealing material 8 is securely sealed. In this example, the side surface of the cathode 3 is covered with thermosetting epoxy resin 3a for insulation. In this way, one ′
The sensor body according to the present invention, in which the electrode body (the cathode 3 in the example shown in FIG. 1) is made of a conductive material mainly composed of carbon and contains a water-insoluble substance, is different from the conventional electrode body made of noble metal. The rigidity is also improved compared to the sensor body with 1
It does not cause dirt to adhere to the surface, the manufacturing method can be simplified, and it is economical enough to be easily disposable.

Furthermore, the electrode body made of carbon containing a water-insoluble substance according to the present invention is a sensor body that exhibits long incision characteristics by suppressing the infiltration of liquid into the body mainly composed of carbon. can be made.

Furthermore, by adding trace amounts of metal compounds such as iron, copper, cobalt, and calcium to the electrode body whose main component is carbon, it is possible to produce a stable polarographic electrode that generates little abnormal noise over a long period of time.

In the present invention, the electrode body made of such a material mainly composed of carbon includes oils and fats, fatty acid derivatives, and wax.

To impregnate a water-insoluble substance selected from wax, polymer materials, pigments, etc., for example, after forming an electrode body, place it in a reduced pressure environment to release the internal gas, and then use the method described above. A method such as impregnating a water-insoluble substance by heating it and immersing it in a molten liquid is used. Although a certain effect can be obtained by such impregnation only in the vicinity of the surface of the electrode body, it is preferable to impregnate the inside of the electrode body from the viewpoint of preventing infiltration of liquid.

FIG. 2 shows an example of a sensor body having another structure according to the present invention. In the figure, an electrode body 3 made of a large number of carbon fibers molded with resin and an electrode body 2 made of silver/silver chloride with a silver chloride layer formed on the outside are both fixed to an insulating body 5a, and further sealed. It is attached to the insulating body 5b by a threaded portion 12.13 with the material 11 in between. The electrode body 3, which is made of a carbon fiber with a resin bottom, is connected to I through a metal spring 14.
The electrode body 2 made of silver/silver chloride is connected to the lead wire 16 via a threaded portion 12.13. A sensitive membrane 17 made of acrylamide gel containing M containing glucose oxidase is supported on the tip. The structure shown in this Figure 2! With the sensor body (;, as shown in Figure 1, the 'rt solution is not used, and the sensitive film is directly bonded to the electrode body, and the electrical signal generated by contact with the measurement sample is read. Take it out from the line and perform measurement analysis.

Even in a sensor body that does not have such an electrolyte,
By impregnating the IE electrode body made of a carbon-based material that makes up the sensor body with a water-insoluble substance to make it water-repellent, leakage caused by infiltration of sample liquid, cleaning liquid, etc. Decrease in measurement accuracy can be suppressed.

In addition to this, we also created a porous shape with carbon as the main component! It can also be a polar body. In such an electrode body, a biochemically active substance such as an enzyme is supported in the pores, and a water-insoluble substance is supported in the other parts, thereby creating a sensor body in which the sensitive membrane and the electrode body are integrated. is configured. In this configuration, in areas other than those carrying biochemically active substances,
No liquid penetration occurs.

On the other hand, when performing measurements using these sensor bodies,
Two similar sensor bodies may be prepared and one of the sensor bodies may not support a biochemically active substance, and these two bodies may be used simultaneously for measurement. In other words, if only a sensor body carrying a sensitive membrane with immobilized biochemically active substances is used, substances other than the analyte contained in the sample solution may interfere with the presence or absence of the sensitive membrane and generate a detection signal. As a result, accurate measurement and analysis of the target substance may not be possible.In such cases, the signal output of a sensor body that does not carry a biochemically active substance and the output signal of a sensor body that carries a biochemically active substance may differ. By taking the difference, the influence of substances other than the target substance to be tested can be canceled out, and accurate measurement and analysis of the target substance to be tested can be performed.

[Embodiments of the invention]

Example 1 Using a material mainly composed of petroleum pitch and asphalt, a raw material containing approximately 0.01 to 0.5 wt% of each of iron, calcium, aluminum, and silicon, with the balance substantially consisting of carbon was molded. After, about 1100-140
It was fired at 0° C. to obtain a rod-shaped body (hereinafter referred to as a carbon rod) with a diameter of 3 mm. Further, this was impregnated with paraffin wax having a melting point of around 80° C. to form an electrode body. After connecting a lead wire to one end of this electrode body, the side surface was coated with a thermosetting epoxy resin. And using this, the first
It was assembled into a sensor body as shown in the cross-sectional view of the figure.

Next, 6. a fluoropolymer membrane with a thickness of about 25 μm is placed in contact with the other end of the cathode 3 made of a carbon rod impregnated with wax. 7. A photosensitive membrane with immobilized glucose oxidase approximately 50 μm thick. Semi-transparent membranes made of cellulose diacetate with a thickness of about 50 μm and having asymmetric pore diameters of 8 and 9 were respectively loaded and prepared in this order. The cathode 3 made of a carbon rod impregnated with wax was used by applying a voltage of -0.8 V to the anode 2 made of a silver/silver chloride electrode. This sensor body was mixed with a pH 5 phosphate buffer solution for 40 m! When contacted alternately with glucose solutions of I/dl, a good response was obtained as shown in the characteristic diagram of FIG. In the figure, a indicates the point of contact with the glucose solution, and b indicates the point of contact with the buffer solution.

Also, the sensor body used in this way can be used for approximately 80 minutes without replacing the membrane.
It was possible to measure up to 00 samples, that is, until the membrane deteriorated and became unusable. This indicates that the lifespan can be extended by approximately 20% compared to the conventional sensor body equipped with an electrode body using platinum. On the other hand, V using this platinum
In the sensor body equipped with the ta body, the sensitivity gradually decreased and the noise increased as measurements continued. When it deteriorated and became unusable, it was disassembled and the platinum electrode body inside was examined, and deposits that were not present when it was first manufactured were found on the surface of the body.

On the other hand, no such deposits were observed on the carbon rod used in the sensor body according to the present invention even after measurement under similar conditions.

〔Effect of the invention〕

The sensor body according to the present invention can be easily manufactured by using a material whose main component is carbon containing a water-insoluble substance instead of the conventional noble metal 'qL, It provides sufficient reaction and stable output over a long period of time for analysis, making it possible to conduct inexpensive and highly accurate analysis.

[Brief explanation of drawings]

1 and 2 are simulated cross-sectional views showing an example of a sensor body according to the present invention, and FIG. 3 is a characteristic diagram showing an output response when a specific component in a sample liquid is measured. 1... Oxygen 1t%, 2... Anode, 3... Cathode. 4... Electrolyte, 5... Insulator cylinder, 5a, 5b...
・Insulating body, 6... Teflon membrane, 7.17...
・Sensitive membrane 8.11...Sealing material, 9...Semipermeable membrane, 1
0,15°16...Lead! ! , 12.13... Threaded part % 14... Metal spring. Agent: Patent Attorney Norihiro H. Kikuo Takehana Figure 1 Figure 2

Claims (2)

[Claims] (1) In a sensor body in which a biochemically active substance is immobilized on the sensitive part of a polarographic electrode used as a basic electrode, one of the two electrode bodies of the polarographic electrode has carbon as a product, A sensor body characterized by containing a substance that is insoluble in water. (2) The sensor body according to claim 1, wherein the water-insoluble substance is selected from oils and fats, fatty acid derivatives, waxes, polymeric materials, and pigments.