JP2003130838A - Water quality sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water quality sensor that can be manufactured in simple construction and at low cost, and also that can easily reproduce deteriorated electrodes and further measure water quality of a small amount of liquid under test. SOLUTION: The water quality sensor measures the water quality of subject liquid electrochemically. Terminal electrodes 2 that are directly brought into contact with the subject liquid upon measurement are formed of metal wire. At least the tip portion of the terminal electrode 2 is buried in a sealing material 4 so that the tip surface of the sealing material 4 and the tip surfaces of the terminal electrode 2 are located on the same plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality sensor for measuring the water quality of a test liquid by an electrochemical method, and more specifically, it is small in size, low in cost, and regenerates electrode characteristics by a simple operation when the electrode deteriorates. The present invention relates to a water quality sensor that can be operated and is easy to maintain.

[0002]

2. Description of the Related Art Conventionally, a redox potential sensor for measuring a redox potential and a sensor for measuring residual chlorine have been widely marketed.

In a conventional general redox potential sensor, an insoluble metal electrode such as platinum is used as a working electrode, and
There is a method in which a reference electrode having a silver-silver chloride electrode as an internal electrode is used as a counter electrode, both electrodes are immersed in a test solution, and a relative potential difference generated between both electrodes is output as a redox potential.

Further, as a residual chlorine concentration measuring sensor using the polarographic method, two electrodes are arranged facing each other in drinking water, a constant voltage is applied between the electrodes in this state, and a current flowing between the electrodes is applied. Some measure residual chlorine concentration.

In addition, Japanese Unexamined Patent Publication No. 9-113483, Japanese Unexamined Patent Publication No. 10-296240, and Japanese Utility Model Publication No. 4-22875.
The publications and the like disclose structures of an oxidation-reduction potential sensor and a residual chlorine concentration sensor. According to these, a platinum electrode or a silver electrode is provided in a plate shape or a thick rod shape. The electrode has a structure protruding from a support body that supports the electrode.

However, in such a conventional water quality sensor, the structure of the reference electrode is complicated, the manufacturing cost is high, and the manufacturing is troublesome. Therefore, the water quality having a simple structure is required. A sensor was needed.

Further, when the water quality is repeatedly measured by the water quality sensor, the surface condition of the electrode is changed, an oxide film is formed on the surface due to surface oxidation by air or surface oxidation by the test solution, and redox in the test solution. The electrode deteriorates due to physical adsorption of substances and impurities. In this case, it is necessary to take out the electrode and polish and regenerate this electrode. With the electrode structure, the work of polishing the electrode is not easy and takes a lot of trouble.

Here, as a conventional electrode regeneration method, for example, chromium sulfuric acid, hot concentrated nitric acid, high hydrochloric acid solution or the like is used as a cleaning agent, and the surface of the working electrode is immersed in the cleaning agent. There is a method to clean the but the cleaning work is not easy because special and dangerous chemicals must be used. In addition, JP-A-10-296242
The publication discloses a method of removing dirt on an electrode by applying a reverse voltage treatment to one electrode of a pair of electrodes by applying a negative voltage to the other electrode. Since a mechanism for reverse charging has to be provided, the structure becomes complicated, leading to high cost.

Further, in the sensor structure as described above, the amount of the test liquid required to immerse the electrode protruding from the support is required, and the water quality of a very small amount of the test liquid cannot be measured. It was a thing.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, has a simple structure, can reduce the cost, and can easily regenerate a deteriorated electrode. Moreover, it is an object of the present invention to provide a water quality sensor capable of measuring the water quality of a small amount of test liquid.

[0011]

A water quality sensor according to claim 1 of the present invention is a water quality sensor for electrochemically measuring the water quality of a test liquid, wherein a terminal electrode 2 which is in direct contact with the test liquid during measurement is used. It is formed of a metal wire, and at least the tip portion of the terminal electrode 2 is embedded in the sealing material 4 so that the tip surface of the sealing material 4 and the tip surface of the terminal electrode 2 are flush with each other. It is characterized by.

According to a second aspect of the present invention, in the first aspect, the terminal electrode 2 is made of a pair of different kinds of metal wires, and at least the tip of each terminal electrode 2 is placed in the same sealing material 4. The front end surface of the sealing material 4 and the front end surface of each terminal electrode 2 are embedded so as to be flush with each other.

According to a third aspect of the present invention, in the second aspect, the pair of terminal electrodes 2 are each formed of a platinum wire on one side, a silver wire on the other side, or a silver wire having a silver chloride coating formed on at least the tip surface. It is characterized by consisting of.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In the example shown in the figure, the water quality sensor 1 is formed as a portable and compact one having a housing 30, a sensor section, a power source section, a control section, an operation section and a display section.

The housing 30 is formed of a resin molded product, and has a power source section and a control section internally, and a main body section 33 having an operation section and a display section on the outer surface, and a front section of the main body section 33. Formed to project forward from the part,
The sensor unit 27 is provided with a sensor unit including a pair of terminal electrodes 2 (2a, 2b) at the tip. The housing 30 is formed of a resin molded product such as ABS resin.

FIG. 7 is a block diagram showing the operation of the water quality sensor. The power supply unit provided inside the main body unit 33 supplies driving power to the control unit, and a small battery such as a button type alkaline battery can be used. The control unit is configured by mounting electronic components such as resistors, transistors, capacitors, and IC chips on a printed wiring board on which a circuit is formed, and the output from the sensor unit is input to this input. Based on the water quality,
The display unit is controlled based on the detection result.

The display section displays the detection result of the water quality detected by the control section based on the output from the sensor section, and is composed of a plurality of light emitting diodes 31 in the example shown in FIG. . This display unit is controlled so that, for example, among a plurality of light emitting diodes 31 constituting the display unit, a specific light emitting diode 31 corresponding to the water quality detected by the control unit is turned on. Further, for example, a liquid crystal display panel is provided as a display unit to display the output value from the sensor unit as it is, or to display the value such as the redox potential derived by counting the output from the sensor unit. You can also

As the operation unit, an operation switch such as a power switch 32 and a setting switch for changing the measurement mode can be provided, and can be constituted by a push button type switch or the like.

The detecting portion 27 of the housing 30 is formed in a cylindrical shape elongated in the front-rear direction, and the hollow portion inside thereof communicates with the main body portion 33 at the rear end side.

As shown in FIG. 1, the tip of the detecting section 27 is provided with a sensor section in which the terminal electrodes 2 (2a, 2b) are sealed and supported by the sealing member 4 in the fixing member 5. . As shown in FIG. 2, the fixing member 5 is formed in a cylindrical shape, and a recess 10 that opens to the front surface is formed on the front end side, and the bottom surface of this recess 10 and the rear end surface of the fixing member 10 are penetrated. Two insertion holes 6 are formed. The insertion hole 6 has an inner diameter of 0.6 mm, for example.

As shown in FIG. 3, the terminal electrode 2 (2a,
2b) is arranged in the hollow portion of the detection portion 27 and is connected to the tips of the lead wires 3 (3a, 3b) each having a diameter smaller than the inner diameter of the insertion hole 6 (for example, 0.5 mm). As the lead wire 3 (3a, 3b), a wire made of an appropriate metal wire such as a copper wire or a nickel wire is used.
Here, the lead wires 3 (3a, 3b) are inserted into the insertion holes 6 of the fixing member 5, the rear end side is pulled out to the rear of the fixing member 5 and is arranged in the hollow portion. Lead wire 3 (3a, 3
b) and the terminal electrode 2 (2a, 2b) are joined by any method such as spot welding or crimping connection, and the inner diameter of the insertion hole 6 is formed at the connection portion between the lead wire 3 and the terminal electrode 2. A hump portion 8 having a larger diameter than that is formed. The tip of the lead wire 3 (3a, 3b) is locked to the bottom surface side of the recess 10 of the fixing member 5 by the bump 8 and the terminal electrode 2 (2a, 2b).
Is provided so as to project forward from the bottom surface of the recess 10 of the fixing member 5. In addition, without providing the lead wire 3, the terminal electrode 2 (2a, 2b) is arranged in the hollow portion of the detecting portion 27, and the tip end portion thereof is inserted into the insertion hole 6 of the fixing member 5, so that the terminal electrode 2 (2a , 2b) to the fixing member 5
It may be provided so as to project forward from the bottom surface of the recess 10.

The terminal electrodes 2 (2a, 2b) are embedded in the sealing material 4 at least at their tips. In the example shown,
The recess 10 of the fixing member 5 is filled with the sealing material 4, and at this time, the front end surface of the sealing material 4 is flush with the opening of the recess 10, or is forward from the opening of the recess 10. It is formed at a position protruding. The terminal electrode 2 (2a, 2b) is embedded by the sealing material 4, and the front end face of the sealing material 4 is formed in a flat shape at this time, and the pair of terminal electrodes 2 (2a, 2b) is It is embedded in the sealing material 4 so that the front end surface is exposed so as to be flush with the front end surface of the sealing material 4. At this time, the terminal electrodes 2 (2a, 2b) are arranged in parallel and in parallel with an interval, and the interval is appropriately set. However, in order to reduce the size and prevent a short circuit in the bump portion 8, Is preferably in the range of 2 to 10 mm.

As described above, since the terminal electrodes 2 (2a, 2b) are embedded in and supported by the sealing material 4, deformation is unlikely to occur, and the terminal electrodes 2 are exposed to a strong water flow during water quality measurement or the terminals. It is possible to prevent the electrode 2 from being deformed or damaged by coming into contact with any object. Therefore, the thin terminal electrode 2 made of a metal wire.
By using (2a, 2b), the electrode material is reduced to reduce the cost, and at the same time, the terminal electrode 2 (2a, 2b)
It is possible to prevent deformation and damage of 2b). At this time, the terminal electrodes 2 (2a, 2b) are preferably formed to have a wire diameter of 0.1 to 1.0 mm in order to improve workability and handleability at the time of manufacturing the sensor portion and reduce cost. It is a thing.

The above-mentioned sealing material 4 is preferably made of a material made of a resin material having both insulation and water resistance, and for example, an epoxy resin can be used.

The pair of terminal electrodes 2 (2a, 2b)
Can be made of an appropriate metal wire depending on the application, but each terminal electrode 2 (2a, 2b) can be made of a different metal. For example, if one terminal electrode 2b is formed of a platinum wire and the other terminal electrode 2a is formed of a silver wire or a silver wire on which a silver chloride coating is formed, the oxidation-reduction potential and the free chlorine concentration of the test liquid are electrochemically determined. A water quality sensor to measure can be configured. When the terminal electrode 2a is formed by forming a silver chloride coating on the silver wire,
Since only the tip surface of the terminal electrode 2a is exposed to the outside, a silver chloride coating may be provided only on the tip surface of the silver wire.

With respect to the fixing member 5, the terminal electrodes 2 (2a, 2a
In providing b), first, for example, the end portion of the terminal electrode 2b made of a platinum wire is spot-welded or caulked to the tip of one lead wire 3b of the two lead wires 3 (3a, 3b) made of nickel wire or the like. In the same manner, the tip of the terminal electrode 2a made of a silver wire is embedded and connected to the tip of the other lead wire 3a by spot welding, caulking, or the like. At this time, the terminal electrode 2 (2a,
The ends of the lead wires 3 (3a, 3b) connected to 2b) are formed as bumps 8. However, the lead wires 3 (3a, 3a, 3b, Three
A platinum wire or a silver wire may be connected to b). At this time, since the silver chloride coating is not formed on the terminal electrode 2a made of a silver wire, electrical connection between the terminal electrode 2a made of a silver wire and the lead wire 3a can be easily ensured.

Next, as shown in FIG. 4, each lead wire 3
(3a, 3b) is inserted into the two insertion holes 6 of the fixing member 5 from the end side on the side where the terminal electrodes 2 (2a, 2b) are not connected. At this time, the lead wire 3 (3a, 3
b) is inserted into the insertion hole 6 from the recess 10 side of the fixing member 5. At this time, the bump 8 at the tip of the lead wire 3 (3a, 3b)
Is locked to the bottom surface side of the recess 10 of the fixing member 5, so that the terminal electrode 2 (2a, 2b) protrudes forward from the opening of the recess 10 of the fixing member 5, and the lead wire 3 (3a, 3b).
b) The rear end side is in a state of being pulled out rearward from the fixing member 5.

In this state, as shown in FIG. 5, the recess 10 of the fixing member 5 is filled with the sealing material 4 for sealing. The sealing material 4 can be filled in the recess 10 by a method such as potting, and can be hardened and molded if necessary. At this time, the sealing material 4 is formed so as to rise from the opening of the recess 10 to the tip side. .

Next, the encapsulating material 4 is cut by cutting it at a portion rising from the opening of the recess 10.
1 is formed by forming the front end face of the above into a plane shape that is substantially orthogonal to the terminal electrode 2 (2a, 2b), and cutting the terminal electrode 2 (2a, 2b) along with the cutting of this sealing material 4, as shown in FIG. In this manner, the front end face of the terminal electrode 2 (2a, 2b) after cutting is flush with the front end face of the sealing material 4 after cutting. The cutting of the sealing material 4 and the cutting of the terminal electrodes 2 (2a, 2b) can be performed by an appropriate method.

At this time, the pair of terminal electrodes 2 (2a, 2b)
Are arranged in parallel and in parallel at intervals, and the entire terminal electrode 2 (2a, 2b) including the tip portion is embedded in the sealing material 4, and the tip surface of the sealing material 4 and each terminal electrode. 2 (2a,
The tip surface of 2b) is flush with the terminal electrodes 2 (2a, 2
The tip surface of b) is exposed to the outside at the tip surface of the sealing material 4.

Next, a silver chloride film is formed on the front end face of the terminal electrode 2a made of a silver wire. At this time, the front end face of each terminal electrode 2 (2a, 2b) is immersed in an aqueous solution of an electrolyte containing chlorine such as an aqueous solution of sodium hypochlorite, an aqueous solution of lithium chloride, an aqueous solution of potassium chloride, etc.
A silver chloride film can be formed on the front end face of the terminal electrode 2a made of a silver wire by causing an electric current to flow between (2a, 2b). For example, 0.01 to 1 of chlorine-containing electrolyte
The front end face of each terminal electrode 2 (2a, 2b) is dipped in a mol / L aqueous solution, and two lead wires 3 (3a, 3b) are formed.
When a voltage of 1.4 to 2 V is applied between b) for 1 to 3 minutes so that the side of the terminal electrode 2a made of silver wire has a higher potential, the front end face of the terminal electrode 2a made of silver wire is A silver chloride film is formed by an electrochemical reaction.

When the silver chloride film is formed only on the front end surface of the terminal electrode 2a made of a silver wire after filling the sealing material 4 in this way, the lead wire 3a and the terminal electrode 2a are separated by the sealing material 4. Lead wire 3 because the connection is sealed
It is surely prevented that a and 3b are immersed in the electrolytic solution,
It is possible to prevent the occurrence of an electrochemical reaction in the lead wires 3a and 3b and to efficiently form the silver chloride film.

Water quality sensor 1 constructed as described above
When the water quality of the test liquid is measured using, the tip of the terminal electrode 2 (2a, 2b) exposed on the tip surface of the sealing material 4 by bringing the tip surface of the sealing material 4 into contact with the test liquid. The surface is brought into contact with the test liquid, and the power switch 32 is turned on. At this time, even if the amount of the test liquid is very small, the tip of the sealing material 4 is simply applied to the surface of the test liquid, and the terminal electrode 2 (2
The tip surface of a, 2b) can be brought into contact with the test liquid.

In this state, a potential difference is generated between the terminal electrodes 2 (2a, 2b) due to the redox potential of the test solution and the concentration of free chlorine, and electromotive force is generated.
The voltage generated between (2a, 2b) is detected, and the light emitting diode 31 of the display section is turned on based on the detection result.
Notify the user of the water quality of the test liquid.

Further, when the front end face of the terminal electrode 2 (2a, 2b) is contaminated by repeatedly measuring the test liquid, the front end face of the sealing material 4 is polished so that the terminal electrode 2 ( The front end faces of 2a and 2b) can be easily cleaned and regenerated. At this time, the terminal electrodes 2 (2a, 2b)
When a silver wire having a silver chloride coating formed on the front end surface is used, the silver chloride coating may be peeled off. In this case, the pair of terminal electrodes 2 (2a, 2b) may be removed. Each terminal electrode 2 (2a, 2a) in tap water containing sodium hypochlorite for sterilization in a short-circuited state
By dipping the front end surface of b), the silver chloride film can be easily reformed by an electrochemical reaction.

In the above-described embodiment, a pair of linear terminal electrodes 2 (2a, 2b) are provided as detection electrodes,
By embedding and supporting the terminal electrodes 2 (2a, 2b) at least at the tips in the same sealing material 4, it is easy to simultaneously contact the two terminal electrodes 2 (2a, 2b) with the test liquid. In this state, the two terminal electrodes 2 (2
The water quality can be measured by an electrochemical method such as measuring an electromotive force generated between a and 2b), but the present invention is not limited to such a form, and is not limited to the electrochemical water quality sensor. It is only necessary to adopt such a configuration for the electrode that is in direct contact with the test liquid.

In the example shown in FIG. 8, as the detection electrode,
A liquid junction part in which an internal electrode 9 having a silver chloride coating formed on silver is placed in a standard solution 10 consisting of a 0.1 mol / L KCl solution in a container 13 and a continuity between the standard solution 10 and a test solution is established. The sensor unit is configured by providing the standard electrode provided with 11 as a reference electrode and the terminal electrode 2 that is brought into direct contact with the test liquid as a working electrode.

In the example shown, in the working electrode, the lead wire 3
And a terminal electrode 2 made of a platinum wire connected to the tip of the lead wire 3 are sealed in a columnar sealing material 4, and at the front end face of this sealing material 4, the terminal is formed. The front end surface of the electrode 2 is exposed so as to be flush with the front end surface of the sealing material 4.
Further, the rear end of the sealing material 4 and the rear end of the lead wire 3 are
It is supported by the fixed member 5. On the other hand, in the comparison electrode, the inner electrode 9 and the container 13 are fixed members 1 provided on the rear end side.
2 is supported by the liquid junction 11 at the front end of the container 13.
Is provided. The fixing members 5 and 12 for the working electrode and the reference electrode are adjacently formed integrally with each other, whereby the working electrode and the reference electrode are provided adjacent to each other.
Further, the front end face of the sealing material 4 in the working electrode and the front end face exposed to the outside of the liquid junction 11 in the comparison electrode are formed flush with each other.

At the time of measuring the water quality of the test liquid, the front end face of the sealing material 4 of the working electrode and the front end face of the liquid junction 11 of the reference electrode are simultaneously contacted with the test liquid. The water quality can be measured electrochemically by, for example, measuring the electromotive force between the electrodes using a voltmeter.

[0041]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Production of sensor part) Lead wire 3 (3a, 3)
For b), use two nickel wires with a wire diameter of 0.5 mm,
The tip of each lead wire 3 (3a, 3b) is tapped to have a diameter of 0.
A bump portion 8 having a size of 6 to 0.7 mm was formed.

As the platinum wire and the silver wire to be the terminal electrode 2, a platinum wire having a wire diameter of 0.1 mm and a silver wire having a wire diameter of 0.2 mm were used because they are easy to handle and inexpensive.

Then, the bump portion 8 of the one lead wire 3b and the end portion of the platinum wire are connected by spot welding, and the end portion of the platinum wire is embedded in the bump portion 8 of the one lead wire 3b. The terminal electrode 2b made of a platinum wire is connected to the wire 3b, and the bump portion 8 of the other lead wire 3a and the end portion of the silver wire are connected by spot welding, so that the bump portion 8 of the other lead wire 3a is silver. A terminal electrode 2a made of a silver wire was connected to the lead wire 3a by embedding the end portion of the wire.

The fixing member 5 is made of vinyl chloride, has an outer dimension of 7 mm, and the insertion hole 6 has an inner diameter of 0.6 m.
m, and the distance between the insertion holes 6 was 2 mm.

Then, the lead wire 3 (3a, 3b) is inserted into the insertion hole 6 of the fixing member 5 from the end on the side where the terminal electrode 2 (2a, 2b) is not connected, and the lead wire 3 (3a, 3a, 3b) is inserted.
The bump 8 at the tip of 3b) was locked to the bottom surface of the recess 10.

Next, an epoxy resin (100: 15 mixture of a base compound and a curing accelerator of "Epoxy ME-352" manufactured by Nippon Pernox Co., Ltd.) was filled in the recess 10 of the fixing member 5 and heated at 100 ° C. for 30 minutes. .

At this time, the sealing material 4 projects from the recess 10 of the fixing member 5, and each terminal electrode 2 (2
The a and 2b) are in a protruding state.

Next, the projecting portion of the sealing material 4 is cut by an end mill mounted on a slicing machine to form a front end face thereof into a flat surface and the terminal electrode 2 (2a, 2b) is cut to obtain a terminal. The front end surface of the electrode 2 (2a, 2b) was formed so as to be flush with the front end surface of the sealing material 4 and exposed.

Next, the front end face of the sealing material 4 was dipped in a 6-fold diluted solution of a cleaning agent (“Pure Soft” manufactured by Inei Morieidou) for 30 seconds, and then dipped in distilled water for 30 seconds. Next, the front end surface of the sealing material 4 was dipped in a 1 mol / L solution of sodium hydroxide for 30 seconds and then dipped in distilled water for 30 seconds.
Next, the front end surface of the sealing material 4 was immersed in a 1 mol / L solution of hydrochloric acid.
After soaking for 0 second, it was soaked in distilled water for 30 seconds. Furthermore, the front end face of the sealing material 4 was immersed again in distilled water for 30 seconds. Here, while the front end face of the sealing material 4 was immersed in these liquids, ultrasonic vibration was applied to the liquid by using an ultrasonic cleaning machine.

Then, the front end face of the sealing material 4 was immersed in a 10% aqueous solution of sodium hypochlorite for 30 minutes to form a silver chloride coating film on the front end face of the terminal electrode 2a made of a silver wire.

(Evaluation of chlorine concentration dependence) From 0 ppm to 2 p
The front end of the above-mentioned sensor part is immersed in an aqueous solution of sodium hypochlorite having a chlorine concentration in the range of pm, and the electromotive force generated between the terminal electrodes 2 (2a, 2b) at this time is applied to the lead wire 3 (3a). , 3b), and the correlation between the chlorine concentration and the electromotive force generated between the terminal electrodes 2 (2a, 2b) was investigated.

The results are shown in Table 1 and FIG.

[0054]

[Table 1]

As is clear from this result, there is a strong correlation between the chlorine concentration and the electromotive force generated between the terminal electrodes 2 (2a, 2b), and the water quality sensor 1 having such a sensor unit can be used. It can be seen that it can be suitably used for detecting the free chlorine concentration of tap water.

(Evaluation of reproducibility) Sample A (sodium hypochlorite solution having a concentration of 0.4 ppm), sample B (alkali ionized water), sample C (trade name "Pocari Sweat") were used for the front end of the above-mentioned sensor section. Otsuka Pharmaceutical Co., Ltd.), sample D
(Product name “Soukenbicha”; Kinki Coca-Cola Bottling) is repeatedly dipped into the terminal electrode 2 (2
The electromotive force generated between a and 2b is applied to the lead wire 3 (3a, 3b).
It was derived by measuring the potential difference between b) and the reproducibility of the electromotive force generated between the terminal electrodes 2 (2a, 2b) was investigated.

Here, the alkaline ionized water of the sample B is an alkaline ionized water conditioner (trade name "Miztopia TK74
5 "; manufactured by Matsushita Electric Works, Ltd.) was used.

The results are shown in Table 2.

[0059]

[Table 2]

As is clear from this result, even if the measurement of the aqueous solution is repeated, there is no significant change in the electromotive force generated between the terminal electrodes 2 (2a, 2b), and there is a high reproducibility. Recognize.

(Evaluation of Detection Performance for Small Samples) The front end surface of the above-mentioned sensor portion is applied to the surfaces of Sample A, Sample B, Sample E (saliva) and Sample F (sweat), and at this time, the terminal electrode 2 (2a , 2b) the electromotive force generated between the lead wire 3 (3
derived by measuring the potential difference between a, 3b),
The electromotive force generated between the terminal electrodes 2 (2a, 2b) was measured.

Here, regarding Sample A and Sample B, 0.
A 1 cm ³ sample was dropped on a glass substrate, and the measurement was performed while the front end surface of the fixing member 5 was in contact with the surface of this sample. For the saliva of sample E, the front end surface of the fixing member 5 was brought into contact with the tongue, and for the sweat of sample F, the front end surface of the fixing member 5 was brought into contact with the surface of the human skin that had sweated. It was measured at.

The results are shown in Table 3.

[0064]

[Table 3]

As is clear from this result, Samples A and B
With respect to the above, no significant change was observed in comparison with the results of the above reproducibility evaluation even with a small amount of sample, and accurate measurement can be performed even with a small amount of sample. In addition, it is possible to measure even a small amount of sample such as sweat or saliva that is difficult to obtain.

(Evaluation of maintainability) First, the electromotive force generated between the terminal electrodes 2 (2a, 2b) was measured while the front end portion of the above-mentioned sensor portion was immersed in the sample A and the sample B.

Then, after the sensor portion was subjected to a treatment for deteriorating the electrode performance, the front end surface of the sealing member 4 of the sensor portion was rubbed while lightly pressing a paper towel moistened with water with fingers. After that, measurement was performed on Sample A and Sample B in the same manner as above.

As the treatment for deteriorating the electrode performance, NO poisoning treatment in which the sensor portion is exposed to an atmosphere of 30 ° C., 80% RH and NO concentration of 100 ppm for 1 hour, and blood is dropped on the front end surface of the sealing material 4. After that, the blood-drying and sticking treatment that was made possible was performed, and the above-described measurement was performed for the sensor unit that has undergone each treatment.

The results are shown in Table 4.

[0070]

[Table 4]

As is clear from these results, even if the electrode performance was deteriorated, the electrode performance could be recovered by performing a simple polishing operation.

[0072]

As described above, the water quality sensor according to claim 1 of the present invention is a water quality sensor for electrochemically measuring the water quality of a test liquid, and the terminal electrode which is in direct contact with the test liquid at the time of measurement is made of metal. Since it is formed of a wire, and at least the tip of the terminal electrode is embedded in the sealing material so that the tip surface of the sealing material and the tip surface of the terminal electrode are flush with each other, the water quality is simple. A sensor can be formed, and the water quality sensor can measure the water quality such as the redox potential and the chlorine concentration of the test liquid. Further, the cost can be reduced by forming the terminal electrode with the metal wire, and the terminal electrode made of the metal wire can be prevented from being damaged or deformed by supporting the terminal electrode with the sealing material. . Further, even when the electrode polarity is deteriorated due to contamination or the like, it is possible to easily polish the terminal electrode and restore the electrode polarity by polishing the tip surface of the sealing material. Further, even when the amount of test liquid is small, the terminal electrode exposed on the end face of the sealing material is brought into contact with the test liquid by simply applying the tip surface of the sealing material to the surface of the test liquid, and It is something that can be measured.

According to a second aspect of the present invention, in the first aspect, a terminal electrode made of a pair of different kinds of metal wires is used, and at least the tip of each terminal electrode is sealed in the same sealing material. Since the tip end surface of the material and the tip end surface of each terminal electrode are embedded at intervals so as to be flush with each other, the electrode structure can be further simplified and the tip end surface of the sealing material It is possible to easily measure the water quality of the test solution by contacting the test solution with two terminal electrodes at the same time just by applying it to the surface and detecting the electromotive force generated between these terminal electrodes. .

According to a third aspect of the present invention, in the second aspect, the pair of terminal electrodes are formed by using a platinum wire on one side and a silver wire on the other side or a silver wire having a silver chloride coating formed on at least the tip surface. In particular, it can be suitably used for measuring the redox potential or the free chlorine concentration of the test liquid.

[Brief description of drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A) is some sectional drawings, (b) is a front view of (a).

FIG. 2 shows a fixing member, (a) is a sectional view,
(B) is a front view.

FIG. 3 is a side view showing a lead wire and a terminal electrode.

FIG. 4 is a cross-sectional view showing a manufacturing process of the sensor unit.

FIG. 5 is a cross-sectional view showing the manufacturing process of the sensor unit, which is subsequent to FIG. 4;

FIG. 6 is a side view showing the overall configuration of the water quality sensor.

FIG. 7 is a block diagram showing the operation of the water quality sensor.

FIG. 8 shows another example of the embodiment of the present invention,
(A) is sectional drawing which shows an outline, (b) is a front view.

FIG. 9 is a graph showing test results of chlorine concentration dependency evaluation.

[Explanation of symbols]

1 Water quality sensor 2 terminal electrode 4 Sealant

Claims (3)

[Claims] 1. In a water quality sensor for electrochemically measuring the water quality of a test liquid, a terminal electrode which is in direct contact with the test liquid at the time of measurement is formed of a metal wire, and at least the tip of this terminal electrode is sealed. A water quality sensor characterized in that a tip end surface of a sealing material and a tip end surface of a terminal electrode are embedded in a material so as to be flush with each other. 2. A terminal electrode comprising a pair of dissimilar metal wires is used, and at least the tip portion of each terminal electrode is placed in the same encapsulating material, and the tip surface of the encapsulating material and the tip surface of each terminal electrode. The water quality sensor according to claim 1, wherein the water quality sensor is embedded so as to be flush with the space. 3. A pair of terminal electrodes are formed of a platinum wire on one side and a silver wire on the other side, or a silver wire having a silver chloride coating formed on at least the tip surface.
Water quality sensor described in.