KR102012473B1 - Electrochemical gas sensor having flexible curved electrode - Google Patents

Abstract

The present invention relates to an electrochemical gas sensor. The electrochemical gas sensor comprises: a case including an empty accommodation space inside and formed for gas to be directed to flow into the accommodation space; an electrolyte installed in the accommodation space; a flexible electrode unit installed in the accommodation space and performing electrolysis by coming in contact with the electrolyte, wherein the flexible electrode unit includes a work electrode, a relative electrode, and a reference electrode to detect a change in the electric current generated in accordance with the gas concentration dissolved in the electrolyte; and three metallic electrodes electrically connecting each electrode of the electrode unit to the outside. The case includes: one or more upper protruding units protruding from the upper surface of the accommodation space to the lower part; and one or more lower protruding units protruding from the lower surface of the accommodation space to the upper part. The electrode unit is installed in the accommodation space in the shape of being bent one or more times by the upper and lower protruding units. A fixing protrusion is formed at an end of the lower protruding unit or the upper protruding unit. The fixing protrusion is fixed by being inserted into a groove formed in the electrode unit. According to the present invention, the fixing protrusion is formed at the end of the protruding unit, and the fixing protrusion is fixed by being inserted into the groove formed in the electrode unit. The flexible electrode unit installed in the accommodation space in the shape of being bent one time or more is stably fixed. So, the electrochemical gas sensor enables a design which widens the accommodation space in which the electrolyte is positioned.

Description

ELECTROCHEMICAL GAS SENSOR HAVING FLEXIBLE CURVED ELECTRODE with Flexible Curved Electrode

The present invention relates to a gas sensor for detecting a gas in the atmosphere, and more particularly to an electrochemical gas sensor for detecting the gas by an electrochemical method.

In general, gas sensors for detecting gases in the atmosphere include semiconductor gas sensors in which a catalyst is added to a metal oxide semiconductor base material such as tin oxide, solid electrolyte gas sensors mainly composed of zirconia oxide, and absorption wavelength of infrared rays. (B) optical gas sensors for viewing the wavelengths of ultraviolet light emission characteristics, and electrochemical gas sensors for measuring the current intensity generated by the redox electrode reaction in the gas electrolyte.

Among them, the electrochemical gas sensor is capable of detecting a large number of gases such as flammable gas, toxic gas, and environmental gas, and can measure even low concentrations of PPP. There is also active research.

The electrochemical gas sensor includes three electrodes and an electrolyte, which are divided into a working electrode, a counter electrode, and a reference electrode, and the electrolyte is maintained at a constant potential between the working electrode and the reference electrode. The electrolysis is performed, and the presence or absence of gas and its concentration are detected by detecting the magnitude of the electrolytic current generated between the working electrode and the counter electrode. At this time, by changing the specific potential according to the type of gas to be detected, the specific gas can be quantitatively detected by selectively proceeding oxidation and reduction reactions.

On the other hand, a number of technologies have been developed to increase the detection sensitivity, reaction speed, coherence, reproducibility, safety, and lifespan of electrochemical gas sensors. Most electrochemical gas sensors have one well-type reservoir or electrolyte in a reservoir. The support is installed or the three electrodes are overlapping, but the structure is installed flat on the top of the reservoir. All use dipping to allow the electrode to come in contact with the electrolyte or to invade.

However, such a conventional structure is difficult to improve the gas detection characteristics of the electrochemical sensor because the electrolyte reservoir is left as an unnecessary space or the large area of the electrode is impossible.

In addition, as the trend toward miniaturization of gas sensors has recently been emphasized, the demand for small electrochemical gas sensors having sufficient detection characteristics is increasing, but there is a limit in miniaturization in conventional structures.

United States Patent No. 4,017,373 European Patent No. 126623 Japanese Patent No. 04544605

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide an electrochemical gas sensor having an improved gas detection characteristic and suitable for miniaturization.

Electrochemical gas sensor with a flexible curved electrode according to the present invention for achieving the above object, the case comprising an empty receiving space therein, the case configured to allow the gas to be detected to enter the receiving space; An electrolyte located in the accommodation space; A working electrode, a counter electrode, and a reference electrode, which are installed in the accommodation space and capable of detecting the change of current generated according to the concentration of the gas to be detected in the electrolyte while performing electrolysis by contacting the electrolyte. An electrode part of a flexible material; And three metal electrodes electrically connecting the electrodes of the electrode unit to the outside, wherein the case includes one or more upper protrusions protruding downward from the upper surface of the accommodation space and protrudes upward from the bottom surface of the accommodation space. It is provided with one or more lower protrusions, the electrode portion is installed in the receiving space in a shape bent at least one time by the upper protrusion and the lower protrusion, the fixing protrusion is formed at the end of the upper protrusion or the lower protrusion, The dragon protrusion is characterized in that the insertion is fixed to the groove formed in the electrode portion.

In the electrochemical gas sensor, the following equation (1) is established between the electrolytic current and the detected gas concentration.

I = (n, F, A, D, C) / δ ---------------------------- (1)

Where I is the electrolytic current, n is the number of electrons generated per mole of gas, F is the Faraday constant, A is the size of the gas diffusion area, D is the diffusion coefficient, δ is the thickness of the diffusion layer, and C is the electrolyte Gas concentration. In the same electrochemical gas sensor, since n, F, A, D, and δ are constant, the electrolytic current is proportional to the gas concentration, so that the gas concentration can be detected by measuring the electrolytic current.

The inventors of the present invention install the flexible electrode portion in the accommodating space one or more times to increase the area of the electrode compared to the flat electrode installed in the accommodating space of the same width. By increasing the A, the electrochemical gas sensor has been developed and applied for a new structure that increases the output sensitivity of the electrochemical gas sensor and shortens the reaction time.

The present invention forms a fixing projection at the end of the upper protrusion or the lower protrusion, to broaden the receiving space in which the electrolyte is located by stably fixing the flexible electrode portion installed in the receiving space in a bent shape one or more times, the groove formed in the electrode portion Fixing protrusion was configured to be inserted into the fixing.

To this end, it is preferable that the upper protrusion or the lower protrusion formed with the fixing protrusion is configured such that two or more structures spaced apart from each other constitute one upper protrusion or the lower protrusion so that the electrolyte can move freely between the structures. If each of the upper and lower protrusions has a wall-like structure, the receiving space in which the electrolyte is located is narrowed, and the movement of the electrolyte and the inflow gas is not smooth. In the present invention, each of the protrusions is composed of a plurality of structures, the electrolyte is located between the structures to ensure the receiving space and at the same time the movement of the electrolyte and gas is easy. At this time, the problem that the electrode part of the flexible material is rolled between the structures can be prevented by fixing the electrode part using a fixing projection.

The electrode part includes a first electrode body having a working electrode formed on a substrate made of a flexible material and a second electrode body formed by separating a counter electrode and a reference electrode from a substrate made of a flexible material, wherein the first electrode body is positioned above the second electrode body. The sieve may be positioned below, and a fixing protrusion may be formed at the end of the lower protrusion, and a groove into which the fixing protrusion is inserted and fixed may be formed on the substrate of the second electrode body.

Preferably, the substrate of the second electrode body is a glass fiber substrate, and the fixing protrusion may be fixed by heat fusion in a state of being inserted into the groove.

The case is composed of a lower case having a lower protrusion and an upper case having an upper protrusion, and the lower case and the upper case are ultrasonically fused to seal the contact surface.

At least the metal electrode has a flat surface in contact with the electrode portion, and preferably has a flat cross section. Preferably, the metal electrode is injection molded and fixed together with the lower case, and the inside of the metal electrode is made of titanium or copper, and the outside of the metal electrode is made of platinum or gold.

According to the present invention configured as described above, by forming a fixing protrusion at the end of the protrusion and allowing the fixing protrusion to be inserted into the groove formed in the electrode portion, the flexible electrode portion installed in the receiving space in a curved shape at least one time is stably fixed. Therefore, it is possible to design a wider accommodating space in which the electrolyte is located.

In addition, the present invention is coupled to the case of the upper and lower by ultrasonic welding, there is an effect that can prevent the leakage of the electrolyte while preventing the air and moisture to enter the side.

In addition, the present invention has the effect of injection molding a metal electrode manufactured in a flat plate shape with the lower case to increase the contact area with the substrate electrode and to be stably fixed to the lower case.

1 is a cross-sectional view showing the structure of an electrochemical gas sensor according to an embodiment of the present invention.
Figure 2 is a perspective view showing a lower case of the electrochemical gas sensor according to an embodiment of the present invention.
Figure 3 is an exploded perspective view of the electrode portion of the electrochemical gas sensor according to an embodiment of the present invention.
4 is a plan view illustrating an upper case of an electrochemical gas sensor according to an exemplary embodiment of the present invention.

With reference to the accompanying drawings will be described embodiments of the present invention;

1 is a cross-sectional view showing the structure of an electrochemical gas sensor according to an embodiment of the present invention, Figure 2 is a perspective view showing a lower case of the electrochemical gas sensor according to an embodiment of the present invention.

As shown, the electrochemical gas sensor of the present embodiment is configured to include a case 100, an electrolyte 200 located in the accommodation space inside the case 100 and an electrode portion 300 installed in the accommodation space.

The case 100 is a body constituting the electrochemical gas sensor, and comprises an upper case 110 and a lower case 120 for ease of assembly. In this embodiment, the accommodation space is formed in the upper case 110, the lower case 120 constitutes a bottom of the accommodation space, the detection target gas in the atmosphere is introduced into the accommodation space through the upper case 110. A gas passage hole 116 is formed in the upper case 110 so that air containing a gas to be detected is introduced, and a plurality of filters 116 are installed to block inflow of external moisture or dust. . The configuration of the gas passage hole and the filter for the gas inlet can be applied without limitation the general gas sensor technology in a range that does not impair the features of the present invention, a detailed description thereof will be omitted.

The upper case 110 and the lower case 120 by ultrasonic welding the contact portion in the assembling process to form a fusion splicing unit 130, thereby completely sealing between the upper case 110 and the lower case 120 to prevent air and moisture It is effective in blocking and preventing electrolyte leakage.

Electrochemical gas sensor of the present invention is characterized in that it comprises a protrusion protruding into the interior of the receiving space, in the present embodiment four upper protrusions protruding downward from the lower surface of the upper case 110 that is the upper portion of the receiving space ( 112 and five lower protrusions 122 protruding upward from the upper surface of the lower case 120 which is a lower portion of the accommodation space are alternately positioned. The protrusions 112 and 122 have a function of supporting the shape so that the electrode part 300 of the flexible material can maintain a curved shape in the accommodation space. The length of the protrusions 112 and 122 protruding may be configured to leave only a gap enough to allow the electrode 300 to pass in order to bend the electrode 300 as much as possible. The distance between the protrusions 112 and 122 can be appropriately adjusted according to the size of the electrochemical gas sensor.

In the electrochemical gas sensor of this embodiment, the fixing protrusion 124 is formed at the end of the lower protrusion 122. The fixing protrusion 124 is inserted into the groove formed in the electrode 300 to stably fix the electrode 300 and to facilitate the assembly process.

On the other hand, in the present embodiment, in order to form a receiving space more wide, as shown in Figure 2, a pair of lower protrusions 122 supporting the electrode portion 300 is bent in the middle and spaced apart from each other at both ends Configured. As such, when the lower protrusions 122 are formed at both ends so that the center thereof is empty, the electrode part 300 is rolled into the space therebetween, and thus the curved shape cannot be maintained when viewed from the side. However, in the present embodiment, since the fixing protrusion 124 formed at the end of the lower protrusion 122 is inserted into the groove formed in the electrode 300, the electrode 200 is rolled into the center empty space. Do not.

In the lower case 120, a support 126 for supporting the electrode 300 is formed around the lower protrusion 122.

The electrolyte 200 is electrolyzed by the current applied between the working electrode and the reference electrode, while the detection target gas introduced through the gas passage hole 116 of the upper case 110 is dissolved to form a gap between the working electrode and the counter electrode. A change occurs in the current.

In this embodiment, the liquid electrolyte 200 is positioned in the receiving space, and when the amount of the electrolyte 200 is too small, there is a problem that the electrode unit 300 does not perform a sufficient function, and the detection is excessively large. It is difficult to introduce the air including the target gas, or the introduced air is difficult to move inside the receiving space. The amount of the electrolyte 200 can be appropriately adjusted in a range in which the above problem does not occur. In the present embodiment, as described above, by positioning the lower protrusions 122 so as to empty the center and spaced apart from each other at both ends, the space of the lower protrusions 122 is secured as a receiving space, so that a sufficient amount of the electrolyte 200 is accommodated. It can be located in, the movement of the electrolyte 200 is free and is not fixed to a certain portion.

The electrode unit 300 is installed in the receiving space 130 and is electrically connected to the outside by the metal electrode 400, and has a structure as shown in the exploded perspective view of FIG. 3. The electrode unit 300 according to the present exemplary embodiment includes a first electrode body 310 having a working electrode 314 formed on a first substrate 312 made of PTFE and a counter electrode on a second substrate 322 made of glass fiber. 324 and a reference electrode 326 are formed together, the first electrode body 310 is positioned above and the second electrode body 320 is located below. 3 is exaggerated to show the thickness of the substrate for the description of the electrode portion, the first substrate 312 of the actual Teflon material and the glass fiber second substrate 322 of the composite glass fiber material is thick enough to bend freely It is a thin enough flexible material.

Both the first electrode body 310 and the second electrode body 320 were overlapped in a state in which the surface on which the electrode was formed was disposed downward, and the counter electrode 324 was interposed between the working electrode 314 and the glass fiber. ) And the reference electrode 326. The second substrate 322 made of glass fiber allows the electrolyte 200 to penetrate and connect the working electrode 314, the counter electrode 324, and the reference electrode 326 through the electrolyte 200.

In this case, the counter electrode 324 and the reference electrode 326 were coated with a conductive carbon material so as to be spaced apart from each other, and the efficiency was improved by arranging the interdigitate shape in which the protruding portions are alternately placed, such as a finger clip. . In addition, the groove 328 formed in the second substrate 322 of the second electrode body 320 is a portion in which the fixing protrusion 124 is inserted and fixed, and the counter electrode 324 and the reference electrode 326 are formed. It was formed where it is not located. As a result, the groove 328 may be strongly coupled to the fixing protrusion 124 irrespective of the counter electrode 324 and the reference electrode 326.

In addition, the fixing protrusion 124 is not simply inserted into the groove 328 formed in the second substrate 322, and an additional configuration for increasing the coupling force may be applied. In the present embodiment, the fixing protrusion 124 is inserted into the groove 328 formed in the second substrate 322 and then positioned, and then pressurized from the top with a heated plate to heat the fixing protrusion 124 to about 200 ° C. The fixing protrusions 124 are slightly melted and thermally fused so as to be bonded to the glass fiber substrate which is the second substrate 322 in a viscous state, so that the fixing protrusions 124 are strongly bonded to the second substrate 322. .

The shape in which the working electrode 314, the counter electrode 324, and the reference electrode 326 are formed is not limited to the illustrated form, and the electrode part structure of the electrochemical gas sensor may be freely applied within the scope of not impairing the characteristics of the present invention. As such, further description is omitted.

Since the electrode part 300 is made of a flexible material, the electrode part 300 may be installed and maintained in a bent form by the protrusions 112 and 122 protruding from the upper case 110 and the lower case 120. As a result, the electrode portion 300 is configured to be longer than the total size of the accommodating space, and the area of the electrode is greatly increased as compared with the case in which the electrode portion is formed in a flat plate type in the accommodating space. At this time, only a part of the electrode part 300 is immersed in the electrolyte 200, but because the electrolyte 200 in a liquid state is invaded along the glass fiber second substrate 322 by a capillary phenomenon, the electrode part ( 300) The whole comes into contact with the electrolyte.

The working electrode 314, the counter electrode 324, and the reference electrode 326 included in the electrode part 300 are electrically connected to the metal electrodes 410, 420, and 430, respectively.

The metal electrode 400 of the present embodiment has a plate shape, not a circular cross section, to improve the contact area with the electrode part 300, and one end of the metal electrode 400 is bent in the lower case 120. Located and the other end is exposed to the outside of the case (100). The metal electrode 400 is injection molded together during the injection process of the lower case 120, and is fixed to the lower case 120 and does not move inside.

The metal electrode 400 according to the present embodiment uses a general metal such as titanium or copper inside and a noble metal such as platinum or gold to improve the chemical resistance and durability, and the entire precious metal such as platinum. The manufacturing cost can be lowered as compared with the case of manufacturing. The external noble metal is preferably formed in a range of several micrometers thick by plating so as not to change the total surface area of the metal electrode.

4 is a plan view illustrating an upper case of an electrochemical gas sensor according to an exemplary embodiment of the present invention.

Figure 4 is a plan view of the upper case with the filter removed, the left side of Figure 4 is a conventional structure, the right side of Figure 4 is a structure according to the invention.

In the upper case 110 from which the filter is removed, a through hole into which gas is introduced into the accommodation space is positioned, and in the related art, a circular through hole 118 is formed, but there is a disadvantage in that the amount of gas inflow is insufficient due to insufficient space utilization. In this embodiment, by forming the fan-shaped or triangular through-holes 119, a wide portion in the same area can be utilized as the through-holes, and the gas inflow efficiency is greatly improved.

As described above, the present invention is formed in the receiving space in which the electrolyte is located in the electrochemical gas sensor, the electrode portion is installed, by forming a protrusion to be installed and maintained in the curved form of the electrode, the maximum length is the width of the receiving space Compared to the flat plate-type structure, the electrode has a longer electrode than the accommodating space, so that the output sensitivity is improved and the reaction time is shortened.

In particular, by inserting and fixing the fixing protrusion fixing protrusion fixing groove formed at the end of the protrusion, there is an excellent effect that can secure the receiving space by changing the structure of the protrusion in various ways.

Furthermore, compared to the conventional electrochemical gas sensor, when the width of the electrode is the same, since the width of the receiving space can be made relatively small, it can be seen that the size of the sensor is small, and finally the configuration suitable for the ultra-small electrochemical gas sensor have.

While the present invention has been described through the preferred embodiments, the above-described embodiments are merely illustrative of the technical idea of the present invention, and various changes may be made without departing from the technical idea of the present invention. Those of ordinary skill will understand. Therefore, the protection scope of the present invention should be interpreted not by the specific embodiments, but by the matters described in the claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

100: case 110: upper case
112: upper protrusion 116: gas passage opening
117: filter 120: lower case
122: lower protrusion 124: fixing protrusion
126: support 130: joint
200: electrolyte
300: electrode portion 310: first electrode body
312: first substrate 314: working electrode
320: second electrode body 322: second substrate
324: counter electrode 326: reference electrode
328: home
400, 410, 420, 430: metal electrode

Claims (10)

A case including an empty accommodation space therein and configured to allow a gas to be detected to flow into the accommodation space;
An electrolyte located in the accommodation space;
A working electrode, a counter electrode, and a reference electrode, which are installed in the accommodation space and capable of detecting the change of current generated according to the concentration of the gas to be detected in the electrolyte while performing electrolysis by contacting the electrolyte. An electrode part of a flexible material; And
Comprising three metal electrodes for electrically connecting each electrode of the electrode unit with the outside,
The case may include one or more upper protrusions protruding downward from the upper surface of the accommodation space and one or more lower protrusions protruding upward from the bottom of the accommodation space, such that the electrode portion is bent at least once by an upper protrusion and a lower protrusion. Installed in the receiving space in the shape,
A fixing protrusion is formed at an end of the upper protrusion or the lower protrusion, and the fixing protrusion is inserted into a groove formed in the electrode part and fixed to the electrochemical gas sensor.
The method according to claim 1,
The electrode part includes a first electrode body having a working electrode formed on a substrate made of a flexible material and a second electrode body formed by separating a counter electrode and a reference electrode from a substrate made of a flexible material.
The first electrode body is located above and the second electrode body is located below,
A fixing protrusion is formed at an end of the lower protrusion, and a groove having a fixing protrusion inserted into and fixed to a substrate of the second electrode body is formed.
The method according to claim 2,
And the substrate of the second electrode body is a glass fiber substrate, and the substrate of the first electrode body is a Teflon (PTFE) substrate.
The method according to claim 3,
The fixing projections are electrochemical gas sensors with a flexible curved electrode, characterized in that the heat-sealed fixed in the state inserted into the groove.
The method according to claim 1,
The upper protrusion or the lower protrusion formed with the fixing protrusion has two flexible structures spaced apart from each other to form one upper protrusion or the lower protrusion, so that the electrolyte can freely move between the structures. Electrochemical Gas Sensors.
The method according to claim 1,
The case includes a lower case having a lower protrusion and an upper case having an upper protrusion,
The lower case and the upper case is ultrasonically welded electrochemical gas sensor with a flexible curved electrode, characterized in that the contact surface is sealed.
The method according to claim 1,
The metal electrode is an electrochemical gas sensor having a flexible curved electrode, characterized in that at least the surface in contact with the electrode portion.
The method according to claim 7,
The metal electrode has a flexible curved electrode having an electrochemical gas sensor, characterized in that the cross-sectional shape.
The method according to claim 6,
The metal electrode is an electrochemical gas sensor with a flexible curved electrode, characterized in that the injection molded with the lower case.
The method according to claim 1,
The metal electrode is an electrochemical gas sensor having a flexible curved electrode, characterized in that the inside is composed of titanium or copper, the outside is composed of platinum or gold.

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