JPH03140858A - Ion electrode - Google Patents

Abstract

PURPOSE:To reduce the cost of the title electrode, to make the performance thereof stable and to facilitate handling thereof by providing an insulating film which covers and insulates a titanium nitride electrode except a sensitive part, and an ion-selective film which covers the sensitive part of the titanium nitride electrode at least. CONSTITUTION:A material having insulative and heat-resistive properties is selected for an electrode support base 1 and the material of appropriate dimensions for operation is used. A working electrode 2 is formed of a titanium nitride film of a thickness 1 mum on the whole surface of the electrode support base 1. A platinum thin film 3 is formed on the working electrode 2, while grooves 4 are formed in the electrode support base 1, and the platinum thin film 3 forms a connecting part for a lead wire. The grooves 4 are provided for dividing the electrode support base 1 into separate bases 1 later and they are formed by dicing from the working electrode 2 side. After an insulative protection film 5 is formed on the electrode support base 1, the base 1 is divided into separate electrode support bases 1 along the grooves 4. Moreover, an ion-selecting film 7 is formed on each of the electrode support bases 1 and a sensitive part 2a of the working electrode is covered therewith. According to this constitution, it is possible to reduce the cost of the electrode and to make the performance thereof stable.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an ion electrode using titanium nitride as an electrode material.

(b) Prior Art Conventionally, in order to electrically measure the concentration of a specific ion in a solution to be measured, a glass electrode using a glass sensitive membrane having selectivity for the specific ion has been used. This glass electrode is made by wrapping an electrode with a glass sensitive film and filling the space between the electrode and the glass sensitive film with an internal liquid.

(c) Problems to be Solved by the Invention The above glass electrode has the problems listed in (1) to (3) below.

■Since it is made of glass, it has poor mechanical strength and is easily damaged, so great care must be taken when handling it.

■Due to use, it tends to get dirty easily and the response speed tends to decrease.

■It is difficult to miniaturize, and many parts of the solution to be measured are required.

■The manufacturing process is complicated and expensive.

■Sufficient care must be taken in storage and management.

■Easy to be affected by the temperature of the solution to be measured.

■Long-term fluctuations in electrode output can be seen.

This invention was made in view of the above, and aims to provide an ion electrode that is low in price, has stable performance, and is easy to handle.

(d) Means and operation for solving the problems In order to solve the above problems, the ion electrode of the present invention includes an electrode support base material, a titanium nitride electrode formed on the electrode support base material,
The device includes an insulating film that covers and insulates the titanium nitride electrode except for the sensitive portion thereof, and an ion-selective film that covers at least the sensitive portion of the titanium nitride electrode.

Since the ion electrode of the present invention does not require the use of easily breakable materials such as glass, it has excellent mechanical strength and is easy to handle. Further, an internal liquid is not required, it is easy to downsize, and even a small amount of the solution to be measured can be measured.

On the other hand, the ion electrode of the present invention has a high response speed because the ion-selective membrane and the titanium nitride electrode are in close contact with each other, and the ion-selective membrane is a thin polymer film and is not easily soiled.
This response speed is unlikely to deteriorate. Furthermore, titanium nitride is a chemically stable substance, does not elute into the solution to be measured, and almost no long-term fluctuations in electrode output are observed.

In terms of manufacturing, the ion electrode of the present invention can be fabricated simultaneously on a large substrate by applying techniques such as photolithography, making it easy to mass produce and reducing the price. can be lowered.

If the price of ion electrodes decreases, they will become disposable and there will be no need to manage them.

(Po) Example An embodiment of the present invention will be described below based on the drawings.

In this example, the present invention is applied to the measurement of potassium ions [K゛]. The following will explain the manufacturing process of the example ion electrode.

FIGS. 2(a) and 2(b) show a state in which the working electrode 2 is formed on the surface of the electrode support substrate 1°. The electrode supporting substrate 1° is made of an insulating and heat resistant material, and is of a suitable size for the work.

In this example, the electrode supporting substrate is 54 mm x 1°.
An alumina ceramic plate with a diameter of 54 mm and a thickness of 0.4 mm is used. Note that the size of the electrode support substrate 1° is not limited to this, and other insulating materials may be used as the material.

The working electrode 2 is a titanium nitride film with a thickness of 1 μm, and the working electrode 2 is a titanium nitride film with a thickness of 1 μm. It is formed over the entire surface. A thin film forming technique such as ion blating or sputtering is applied to this working electrode 2.

3(a)(bl) shows a state in which a platinum thin film 3 is formed on the working electrode 2, and grooves 4, . . . , 4 are formed in the electrode support substrate 1°. , is for forming the connection part of the lead wire (or connector) described later, and is made into a strip shape (width 3 mm) using sputtering or vacuum evaporation method.
, approximately 1000 mm thick).

The grooves 4, . . . , 4 are for later dividing the electrode support substrate 1° into individual substrates 1, and are formed by dicing from the working electrode 2 side. In this embodiment, grooves 4,...
, 4 has a depth of 10 μm and a width of 600 μm.

FIGS. 4(a) and 4(b) show a state in which an insulating protective film 5 is formed on the electrode support substrate 1°. The insulating protective film 5 is
The surface of the electrode support substrate 1° is coated with a polyimide-based photosensitive resin film, and a photomask (not shown) is applied to this photosensitive resin film.
After exposure, unnecessary portions were removed by development and rinsing, and the thickness was 5 μm in this example. After removing unnecessary parts, the working electrode sensitive part 2a and the platinum thin film 3 are sprayed out from the parts 5a and 5b, respectively. In this embodiment, the sensitive part 2a is 2 mm x 2
Although the shape and area of the sensitive portion are not limited to this, the design can be changed as appropriate.

The electrode support substrate 1° is divided into individual electrode support substrates 1 along grooves 4 after forming an insulating protective film 5 thereon. This division is performed by dicing the center of the groove 4 (width 150 μm).

A lead wire 6 is connected to the platinum thin film 3 using solder or adhesive paste [see FIG. 1(a)]. This connection location is filled with epoxy resin 8 to provide insulation and reinforcement.

Furthermore, an ion-selective membrane 7 is formed on the electrode support substrate 1, and the working electrode sensitive part 2a is covered with it [Fig. 1(a)
(b)]. This ion-selective membrane 7 is composed of a base layer 7a and an ion-selective layer 7b. Base layer 7a
is 20 ml of polyvinyl chloride in 3 ml of tetrahydrofuran.
The electrode supporting substrate 1 is deep-coated in a solution containing 0 mg of 0 mg of the fluorine-containing material dissolved therein (dip coating) and dried at 60° C. for 60 minutes.

The ion selective layer 7b was prepared by adding 10 mg of bis[(benzo-15-crown-5)-4'methyl]pimelate and 200 mg of polyhinyl chloride to 3 ml of tetrahydrofuran. The solution was dissolved, dipped in 0-nitrophenyl octyl ether 1, and dried at 60°C for 60 minutes. The above screw [(Hense 15-Crown 5)-4'
-Methyl] Pimeley!・ becomes a neutral carrier.

Next, the characteristics of the example ion electrode 10 will be explained, but before that, the measurement system II) F: used for measuring the characteristics will be explained with reference to FIG. 12 is a constant temperature bath, inside which is a 0.1 molar phosphate buffer solution 1 adjusted to pH 6.9.
3 are stored. This phosphate buffer solution 13 is stirred by a Stark 14, and 15 is a rotor of this Stark 14.

The ion electrode 10 is immersed in this phosphate buffer solution 13 together with the saturated Calimero electrode 16 . The ion electrode 10 and the saturated Calimero electrode 16 are connected to a potentiometer 18 via lead wires 6 and 17, respectively, and the potential (electrode output) of the ion electrode 10 with respect to the saturated Calimero electrode 16 is measured.

A predetermined amount of potassium ion solution is injected into the phosphate buffer 13 using a micropipette (not shown). This potassium ion is captured by the potassium ion neutral carrier in the ion-selective membrane 7. The potential difference generated by this trapping is measured with the working electrode 2, and the phosphate buffer 1 is
You can know the potassium ion concentration in 3.

FIG. 6 shows the electrode output [mV] for several potassium ion concentrations. By connecting the plotted points in the diagram to form a calibration curve, unknown samples such as potassium ions in blood can be quantified.

FIG. 7 is a longitudinal cross-sectional view showing a modified example ion electrode 10°. This ion electrode 10' has a platinum thin film 3 exposed and is connected to the outside through a connector 20.

When the ion electrode 10° is inserted into the insertion port 21 of the connector 20, the spring-like contact 21 comes into pressure contact with the platinum thin film 3, and an electrical connection is established.

Note that in the above embodiment, a potassium ion neutral carrier is used, but the carrier is not limited to this, and the design can be changed as appropriate.

(f) Detailed Description of the Invention As described in detail, the ion electrode of the present invention includes an electrode support base material, a titanium nitride electrode formed on the electrode support base, and a titanium nitride electrode covered except for the sensitive part. Since it comprises an insulating film for insulation and an ion-selective film covering at least the sensitive part of the titanium nitride electrode, it has the following effects.

■It has excellent mechanical strength and is easy to handle.

■Response speed is fast, and there is little deterioration in response speed due to dirt.

■Easily miniaturized and can be measured with a small amount of sample.

■Chemically stable, with little long-term fluctuation in electrode output ■It has excellent productivity and can be lowered in price.

■ [Disposable] is possible, and there is no need to manage the electrodes.

[Brief explanation of the drawing]

FIG. 1(a) is an external perspective view of an ion electrode according to an embodiment of the present invention, and FIG. 1(b) is a cross-sectional view of the same ion electrode taken along line 1b-1b in FIG. 1(a). Figures 2 to 4
The figures are diagrams explaining the manufacturing process of the same ion electrode, and FIG. 2(a) is a perspective view showing a state in which a working electrode is formed on the electrode supporting substrate, and FIG. 2(b) is a diagram illustrating the same electrode supporting substrate. Figure 2 (
a) Cross-sectional view of main parts along the middle nb-nb line, Figure 3 (
a) is a perspective view showing a state in which grooves are formed on the electrode support substrate, and Figure 3, etc.) are views of the same electrode support substrate in Figure 3 (a) and ■b.
4(a) is a perspective view showing a state in which an insulating protective film is formed on the electrode support substrate, and FIG. 4(b) is a sectional view of the main part taken along the ~mb line. (IVb in al.
5 is a sectional view of the main part along the -IVb line, FIG. 5 is a measurement system applied to the ion electrode of the example, FIG. 6 is a diagram showing the characteristics of the ion electrode, and FIG. 7 is a modification of the ion electrode. FIG. 1: Electrode supporting substrate, 2: Working electrode, 2a: Working electrode sensitive part, 5: Insulating protective film, 7: Ion selective membrane. Patent applicant

Claims (1)

[Claims] (1) An electrode support base material, a titanium nitride electrode formed on the electrode support base material, an insulating film that covers and insulates the titanium nitride electrode except for the sensitive part thereof, and at least the sensitive part of the titanium nitride electrode. An ion electrode comprising a covering ion selective membrane.