JPH0561580B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reference electrode, particularly an ultrafine and stable silver/silver chloride reference electrode, and a method for manufacturing the same.

[Prior art] Conventionally, the reference electrode is a silver/silver chloride electrode containing a KCl saturated solution in an internal liquid chamber, and an electrode in a glass chamber with a diameter of 2 to 3 cm is generally used to allow good communication with the external solution. ing. In particular, in this case it is necessary that the internal Ag ⁺ Cl ^- ions and the external solution can come and go. Therefore, there are problems such as internal liquid contamination and external Cl ^- ions affecting the electrodes and changing the potential.

In order to solve these problems, (1) prevent the internal AgCl from flowing out as much as possible, (2) configure the in-phase system of Ag/AgCl, and (3) use the test solution (containing Cl ^- ), it is desired to be able to indicate a reference potential without being affected by Cl ^- ions.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problem in a solid type (hybrid type)
The purpose is to provide an ultra-small and stable reference electrode with almost no AgCl outflow.

[Means and effects for solving the problem] As a means for solving the problem, the reference electrode of the present invention includes a conductive substrate and an ion beam sputtering method for coating the surface of the conductive substrate. and an insulating material layer containing silver chloride dispersed therein.

[Example] First, the ion beam sputtering method used in this example will be explained. The ion beam sputtering method sends an inert gas such as argon, ionizes it with ionized plasma, accelerates the ions in a strong electric field, and uses the acceleration energy to eject target atoms and molecules. Deposit on substrate. The feature of this method is that it utilizes the principle of directly converting the kinetic energy of argon into the kinetic energy of the atoms or molecules of the target, so that it can form a film without much heating of the target. In particular, this method is suitable for forming organic films because the film can be formed without undergoing thermal denaturation of the film composition.

A schematic diagram of an ion beam sputtering apparatus and an ion gun is shown in FIG. 2a. The experimental conditions in this case are as follows.

Output: 10W (5KV, 2mA) Vacuum level: 3 x 10 ^-5 Torr or less Time: Any setting conditions Ion beam: Argon The insulating material layer containing dispersed silver chloride to be formed has a thickness of 500 Å to 100 μm, preferably 500 μm. ~1000 Å thick.

As the insulating material, tetrafluoroethylene (manufactured by Teflon Dubon), polystyrene, fluorine-based organic compounds, aromatic polyparaxylylene, etc. are used.

Example 1 FIG. 1 shows the reference electrode of this example.

In the argon ion beam sputtering apparatus shown in Fig. 2a, a silver layer 2 of about 2000 Å thick was formed on one side of an indium tin oxide glass (ITO) 1 by vapor deposition as a substrate, as shown in Fig. 2b. Using a target (a target made by embedding silver chloride in a pallet manufactured by Teflon Dubon), an insulating material layer 5 of approximately 1000 Å thick with silver chloride dispersed in Teflon was created.
An electrode was prepared in which the base was coated with a silver/silver chloride mixed film consisting of silver layer 2. Note that during the creation of the insulating material layer 5, the electrodes were protected by resist, and the copper wire 3 was connected as a lead wire with phosphor bronze 4 (contact).The periphery was sufficiently covered with epoxy resin 6 as an insulating material, and then acetone was applied. The resist was peeled off.

The creation conditions were: Output: 10W (5KV, 2mA) Vacuum degree: 3×10 ^-5 Torr Time: 8 hours.

Annealing the above electrodes (120℃, 10 hours)
As a result, we attempted to diffuse and stabilize the membrane.

Experimental Example 1 The electrode prepared by the method of Example 1 was used as a working electrode, and a saturated calomel electrode was used as a comparison station, and the PH concentration was adjusted to HCl−.
The potential of the electrode was measured when the PH concentration was varied from about 1 to about 10 while adjusting with KOH, but with [Cl ^- ] constant.

The results are shown in Figure 3. Almost no change in potential was observed, indicating that it can be used as a reference electrode.

Experimental Example 2 The electrode prepared in Example 1 was used as the working electrode, a saturated calomel electrode was used as the comparison electrode, and the Cl ^- ion concentration (KCl concentration was varied from 10 ^-2 M/l to 10 M/l).
When we examined the effects of this, the results were as shown in Figure 4.

In this way, it was found that the electrode of this example was hardly affected by the Cl ^- ion concentration, and that it could be used as a reference electrode even under Cl ^- ions.

As described above, the reference electrode of this example is (1) covered with Teflon (registered trademark) (insulating material film), and since the ion beam method is used, Teflon, which is designed in an atomic or molecular shape, (Registered Trademark) structure makes it difficult for AgCl to leak out.

(2) Moreover, the Teflon (registered trademark) film is a thin film of 1000 Å or less, preferably 500 Å to 1000 Å,
Response speed is quick. If it exceeds 100μm,
The response speed becomes slow and peeling tends to occur.

(3) The ITO glass surface is coated with AgCl and Ag (vapor deposition method), and Ag ⁺ ions are constantly supplied from the substrate. Further, AgCl exists in an island shape surrounded by a Teflon (registered trademark) base material. From the above, an AgCl/Ag electrode can be created using an in-phase configuration.

(4) Using this method (ion beam sputtering method), the AgCl site can be easily deposited even on ultra-small sensitive parts, so it can also be used as a reference electrode for ISFETs (ion-selective field-effect transistors). I can,
Other ultra-small sensors can also be expected to find wide use as hybrid reference electrodes.

[Effect of the invention] According to the present invention, a solid type (hybrid type)
There is almost no outflow of AgCl, and an ultra-small and stable reference electrode can be provided.

In more detail, (1) Since it is covered with Teflon (registered trademark) (insulating material film) and uses the ion beam method, AgCl is It has a characteristic that it is difficult to leak outside.

(2) The ITO glass surface is coated with AgCl and Ag (vapor deposition method), and Ag ⁺ ions are constantly supplied from the substrate. The AgCl is also present on islands surrounded by a Teflon matrix. From the above, an AgCl/Ag electrode can be created using an in-phase configuration.

(3) Using this method (ion beam sputtering method), the AgCl site can be easily deposited even on ultra-small sensitive parts, so it can also be used as a reference electrode for ISFETs (ion selective field effect transistors). I can,
It is expected that it will be widely used as a hybrid reference electrode for other ultra-small sensors.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of the reference electrode of this example, Fig. 2a is a schematic diagram of the ion beam sputtering apparatus and ion gun used in this example, and Fig.
Figure b is a diagram showing an example of the target used in this example, Figure 3 is a diagram showing changes in potential with respect to hydrogen ion concentration of the reference electrode of this example, and Figure 4 is a diagram showing chloride ions of the reference electrode of this example. FIG. 3 is a diagram showing changes in potential with respect to concentration. In the figure, 1...ITO, 2...silver layer, 3...copper wire,
4... Phosphor bronze, 5... Insulating material layer, 6... Epoxy resin.

Claims (1)

[Scope of Claims] 1. A reference electrode comprising an electrically conductive substrate and an insulating material layer containing dispersed silver chloride and covering the surface of the electrically conductive substrate. 2. The conductive substrate is made of a material selected from insulators, semiconductors, and conductors, and a thin layer of silver or a material partially containing silver is adhered to one side of the substrate. A reference electrode according to claim 1, characterized in that: 3 For targets where insulating material and silver chloride coexist,
A method for manufacturing a reference electrode, which comprises irradiating the target with an ion beam and sputtering the target to form an insulating material layer containing silver chloride on a desired conductive substrate at a low temperature. 4. The conductive substrate is made of a material selected from insulators, semiconductors, and conductors, and a thin layer of silver or a layer of material partially containing silver is adhered to one side of the substrate. A method for manufacturing a reference electrode according to claim 3, characterized in that: