JPH04264248A - Manufacture of electrochemical electrode and its liquid junction - Google Patents

Abstract

PURPOSE:To obtain an extremely small electrochemical reference electrode whose liquid junction diameter at the tip of the electrode applicable to a very small electrolyte cell is extremely small. CONSTITUTION:A fine tube 13 is integrally formed at the lower end of a main body glass tube 1 whose inner diameter is equal to an outer diameter of a lead terminal 6, and a heat-resistant fine fiber is provided in the fine tube 13 to prevent electrode solution 4 from leaking to provide a liquid junction 2 applicable to a very small electrolyte cell, while the lead terminal 6 is directly connected to the main body glass tube 1 to make a reference electrode extremely small.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference electrode such as a silver-silver chloride electrode or a calomel electrode used as a reference electrode when measuring the electrode potential of a sample placed in an electrolytic solution.

0002

2. Description of the Related Art Conventionally, a silver-silver chloride electrode is manufactured by bonding a liquid junction 22 made of glass or ceramic with a hole 23 to the lower end of a glass tube 21, as shown in FIG.
A KCl aqueous solution 24 is put inside the tube 21, and an Ag
It is constructed by adhering a lid member 27 into which an Au-plated Cu lead terminal 26 to which a /AgCl-treated Ag wire 25 is connected is inserted and fixed.

0003

[Problems to be Solved by the Invention] The above conventional reference electrode is
Since the diameter of the liquid junction 22 is approximately 5 mm, an electrolytic cell large enough to accommodate this is required. Therefore, it is used when the sample liquid is expensive, or for scanning tunneling microscopes (STM), quartz crystal weighers (QCM), scanning vibrating electrodes (SVET), etc. that use electrolytic cells with extremely small volumes (for example, 1 cc or less). I can't.

[0004] As a method of reducing the size of the liquid junction as much as possible, an extremely thin glass tube is made and silver is placed inside it.
In the case of a silver chloride electrode, it is conceivable to make it by adding a KCl aqueous solution, but if it is made too thin, the electrolyte will not enter the liquid junction, making it impossible to perform measurements. Furthermore, if the diameter is too thick, the KCl aqueous solution will leak into the electrolytic cell, changing the characteristics of the sample solution, making it impossible to perform accurate measurements. Therefore, at present, it has not been possible to create a liquid junction consisting of a thin tube that conducts liquid but does not leak liquid.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to solve the problem of an extremely small diameter liquid junction at the tip of an electrode, which can be applied to a small electrolyte cell. An object of the present invention is to provide a microelectrochemical reference electrode and a method for manufacturing its liquid junction.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the electrochemical electrode of the present invention has a thin tube integrally formed at the lower end of the main glass tube, and a fiber is provided in the thin tube to form a liquid junction. It was established as a department.

[0007] In addition, the method for manufacturing the liquid junction includes integrally forming a small-diameter tube at one end of the main glass tube, inserting a heat-resistant fiber into the small-diameter tube, heating the small-diameter tube, and inserting a heat-resistant fiber along the fiber. It is made by stretching a small diameter tube to form a thin tube, bringing it into close contact with the outer periphery of the fiber material, and cutting it along with the fiber, leaving a predetermined length.

[0008]

[Operation] The liquid junction has a thin tube at the lower end of the main glass tube.
Since the fiber is contained therein, the electrolytic solution inside the cell can penetrate into the capillary due to the action of osmotic pressure and form a liquid junction, without the solution inside the electrode leaking to the outside. Since the liquid junction is a thin tube, it can be applied to devices that require extremely small electrolyte cells.

According to the above manufacturing method, a thin tube can be made by heating and stretching a small diameter tube so that the inner side is in close contact with the outer periphery of the fiber. You can get a link.

0010

EXAMPLE FIG. 1 shows a silver-silver chloride electrode. In FIG. 1, 1 is a main glass tube, 2 is a liquid junction formed at the tip of the main glass tube 1, and 4 is a KC placed in the main glass tube 1.
1 is a saturated aqueous solution, 5 is an Ag wire whose surface has been subjected to Ag/AgC1 treatment, and 6 is an Au wire partially inserted into the upper end of the glass tube 1 and bonded with, for example, an epoxy repair agent.
This is a plated lead terminal, and an Ag wire 5 is connected to it.

The liquid junction part 2 of this embodiment is formed by forming the tip of the glass tube 1 into a thin tube shape with an outer diameter φ2 of about 0.1 to 0.3 mm, for example, and a tube with a thickness of about 0.1 μm or less inside the thin tube. It is constructed by filling threads 3 made of quartz fibers.

This reference electrode has an inner diameter of the main glass tube 1 and an outer diameter of the terminal φ1=1.5 mm, and a length L2 of the glass tube=2.
0mm, length of liquid junction L3 = 5mm, length of lead terminal 6 L4 = 13mm, length of exposed part of terminal 5 L5 = 8mm
, famous pixel of liquid junction L3 = 5mm, total length L1 = 28m
It is made in m.

Liquid junction part 2 of the reference electrode constructed as above
Since the tip has a thin tube shape with an outer diameter of about 0.1 to 0.3 mm, it can be applied to devices using extremely small electrolyte cells, and the inside of the thin tube is filled with fibers. In addition, since the internal solution is filled with a saturated solution of KC1, liquid junction can be performed without the internal solution leaking into the cell due to osmotic pressure or the like.

Next, the method for manufacturing the liquid junction of the reference electrode is shown in FIG.
The explanation will be based on.

First, as shown in FIG. 2A, a glass tube 11 having a tapered tube section 12 at one end and a small diameter tube section 131 at its tip is prepared. The glass tube 11 may have the tapered tube section 2 and the small diameter tube section 131 formed in advance, or may be formed each time by heating one end of the glass tube.

Next, as shown in FIG. 2(b), the small diameter pipe portion 1
A heat-resistant fiber (thread) 31 made of, for example, quartz is inserted into the fiber 31 . The thread 31 may be made of a material that is more heat resistant than the glass used for the glass tube, and is not limited to quartz, but may also be made of alumina, carbon, or the like.

Then, as shown in FIG.
1 is softened, its end is stretched along the thread 31 in the direction of arrow a in the figure. As a result, as shown in FIG. 2(d), a thin tube portion 132 is formed, and its inner periphery is brought into close contact with the outer periphery of the thread 31.

Finally, as shown in FIG. 2(e), it is cut leaving a portion necessary as a liquid junction.

According to the above manufacturing method, the small diameter tube portion 131 serving as the liquid junction can be formed to have an extremely thin outer diameter φ2 of about 0.1 to 0.3 mm.
Preferably, the fiber 1 is made of a fiber having a thickness of about 0.1 μm or less. The thicknesses of the fibers and threads are appropriately set depending on the diameter of the liquid junction to be formed.

[0020]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

(1) Since the diameter of the liquid junction is small, it can be applied to extremely small cells. Therefore, in addition to ordinary electrochemical experimental cells, the present invention can be applied particularly to devices requiring microcells such as STM, QCM, and SVET.

(2) According to the manufacturing method of claim 2, an extremely thin liquid junction can be easily produced.

[Brief explanation of the drawing]

FIG. 1 (A) A side sectional view of a reference electrode according to an embodiment of the present invention, (B) An enlarged view of part A in (A).

[Figure 2] A manufacturing process diagram of the same liquid junction.

FIG. 3 is a side sectional view of a conventional reference electrode.

[Explanation of symbols]

1, 21... Main body glass tube, 11... Glass tube, 2, 22...
Liquid junction, 3... Heat-resistant fiber, 4, 24... KCl aqueous solution, 5, 25... Ag wire, 6, 26... Lead terminal, 7... Adhesion, 27... Lid member.

Claims (2)

[Claims] [Claim 1] An ultra-compact electrochemical reference electrode used as a reference electrode, characterized in that a thin tube is integrally formed at the lower end of a main glass tube, and a fiber is provided in this thin tube. . 2. A small-diameter tube is integrally formed at one end of the main glass tube, a heat-resistant fiber is inserted into the small-diameter tube, the small-diameter tube is heated, and the small-diameter tube is extended along the fiber to form a fiber. A method for manufacturing a liquid junction of an electrochemical electrode, characterized in that the liquid junction is made by closely adhering to the outer periphery of a material and cutting it along with fibers, leaving a predetermined length.