KR100823319B1 - Hybrid oxygen gas sensor - Google Patents

Abstract

A hybrid oxygen gas sensor is provided to increase a responsive speed of oxygen gas in a cathode by increasing diffusion speed of the oxygen gas passing through a thin non-porous diffusion barrier. A hybrid oxygen gas sensor includes a housing(10), an oxygen inflow capillary tube(12), a pressure buffer film(40), a non-porous diffusion barrier(50), a cathode(60), and an anode(65). The housing is made of polymer for preventing damage by electrolyte, consists of upper and lower housings(10a,10b). The upper and lower housings are coupled to each other and contain the cathode, anode, and the electrolyte. The oxygen inflow capillary tube is formed on the housing for inflow of oxygen gas into the housing. The pressure buffer film is formed below the oxygen inflow capillary tube prevents elements inside the housing caused by sudden pressure change. The non-porous diffusion barrier is thin, is formed below the pressure buffer film, and controls amount of the oxygen gas which takes part in reduction at the cathode. The cathode is formed below the non-porous diffusion barrier where the reduction is occurred. Oxidation is occurred in the anode.

Description

Hybrid oxygen gas sensor

1 is a cross-sectional view of a hybrid oxygen gas sensor according to an embodiment of the present invention.

FIG. 2 is an exploded view of the hybrid oxygen gas sensor of FIG. 1.

3 is a graph measuring the output signal according to the oxygen concentration in the hybrid oxygen gas sensor according to an embodiment of the present invention.

Figure 4 is a graph measuring the output signal over time in the hybrid oxygen gas sensor according to an embodiment of the present invention.

5 is a graph measuring the response speed of the hybrid oxygen gas sensor according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: housing 10a: upper housing

10b: lower housing 12: capillary for oxygen inlet

14: jamming portion 20: filter

30: O-ring 40: pressure buffer film

50: non-porous diffusion barrier 60: cathode

65: anode wood 70: upper separator

71: engaging hole 72: lower separator

80: ion collector 82: opening

90: electrolyte solution 92: electrolyte solution receiving layer

100: hybrid oxygen gas sensor 110: printed circuit board

112: output terminal

The present invention relates to an electrochemical oxygen gas sensor, and more particularly, to provide a linear output value for the entire concentration range of the oxygen gas and to improve the stability against external pressure changes while reducing the response time for the oxygen gas. To a hybrid oxygen gas sensor.

In general, an electrochemical sensor is used to easily measure the concentration of a specific gas. The electrochemical sensor uses a phenomenon in which the amount of electrons generated during the oxidation and reduction of a gas to be measured is proportional to the concentration of the gas. In the case of oxygen measurement, the principle of a galvanic cell is used.

The galvanic oxygen gas sensor is composed of an oxygen inlet, a cathode, an anode, and an electrolyte. Oxygen that enters the sensor through the oxygen inlet is reduced by the reduction reaction in the cathode and the oxidation occurs at the anode. . As the ions generated by the oxidation and reduction reaction move between the electrodes through the electrolyte, current flows between the two electrodes. At this time, the amount of current flowing between the two electrodes is proportional to the amount of oxygen reduced at the cathode, and the amount of oxygen reduced at the cathode depends on the amount of oxygen introduced into the sensor from the outside, that is, the amount of external oxygen. The output shows the amount of external oxygen.

In the case of the gas sensor using oxygen diffusion through the diffusion barrier and the oxygen flow of the galvanic oxygen gas sensor is not directly introduced, the amount of current between the two electrodes has a linear relationship with the partial pressure of external oxygen, Since the diffusion rate of oxygen is too slow, the response speed of the gas sensor is remarkably slow, which makes it difficult to use in reality.

The technical problem to be achieved by the present invention is to provide a hybrid oxygen gas sensor that can provide a linear output value for the entire concentration range of the oxygen gas and improve the stability against external pressure changes while reducing the response time for the oxygen gas. It is.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Hybrid oxygen gas sensor according to an embodiment of the present invention for achieving the technical problem, the housing is formed with a capillary for oxygen inlet having a diameter of 0.1 to 1mm, and is located in the housing below the oxygen inlet capillary A porous pressure buffer membrane for buffering external pressure changes, and having a thickness of 1 to 50 μm, blocking electrolyte, permeating only gas components, and controlling the amount of oxygen gas participating in the reduction reaction, A non-porous diffusion barrier, a cathode located below the non-porous diffusion barrier, an electrolyte receiving layer positioned below the cathode and filled with the electrolyte, and an anode facing the cathode with the electrolyte receiving layer interposed therebetween. do.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a hybrid oxygen gas sensor according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a hybrid oxygen gas sensor according to an embodiment of the present invention, Figure 2 is an exploded view of the hybrid oxygen gas sensor of FIG.

1 and 2, the hybrid oxygen gas sensor 100 according to an exemplary embodiment of the present invention may include a housing 10, an oxygen inlet capillary 12 formed on the housing 10, and And a pressure buffer film 40, a non-porous diffusion barrier 50, and a cathode 60 sequentially disposed below the capillary tube 12 for oxygen inflow in the housing 10. And an anode 65 facing the cathode 60 with the electrolyte receiving layer 92 therebetween in the housing 10.

Here, the housing 10 is a container made of a polymer material which is not damaged from the electrolyte solution 90, and consists of an upper housing 10a and a lower housing 10b, and the cathode 60, the anode wood 65, and the electrolyte solution therein. 90 can be accommodated. The upper housing 10a and the lower housing 10b may be completely sealed and coupled so that the electrolyte 90 therein does not leak out of the housing 10.

At least one capillary 12 for oxygen inflow is formed on the upper surface of the upper housing 10a so that external oxygen gas is introduced into the housing 10. The capillary 12 for oxygen inflow serves to prevent the components inside the housing 10 from being damaged due to a sudden change in the external environment, for example, a pressure change. Therefore, in order for the oxygen gas to diffuse in a mass flow controlled type through the oxygen inlet capillary tube 12, the diameter d of the oxygen inlet capillary tube 12 is preferably about 0.1 to 1 mm. When the diameter d is less than about 0.1 mm, the diffusion rate of the oxygen gas passing through the oxygen inlet capillary 12 may be too low, thereby slowing the response speed of the hybrid oxygen gas sensor 100. In addition, when the diameter (d) is larger than about 1mm, the oxygen partial pressure is the same in the outside and inside of the housing 10 with the capillary tube 12 for oxygen inflow therebetween, so that the sudden change in pressure of the housing 10 causes the There is a fear that the internal components, such as the non-porous diffusion barrier 50 formed of a thin film, are damaged.

The filter 20 positioned on the outer surface of the housing 10 to the upper side of the oxygen inlet capillary 12 serves to block foreign substances such as dust into the inside through the oxygen inlet capillary 12. For example, the filter 20 may be made of porous PTFE (PolyTetraFluoroEthylene).

The pressure buffer membrane 40 positioned inside the housing 10 below the oxygen intake capillary 12 is, like the oxygen intake capillary 12, due to a sudden change in the external environment, for example, due to a pressure change. (10) It acts as a cushioning material to prevent internal components from being damaged. The pressure buffer membrane 40 may be made of a porous membrane. For example, the pressure buffer membrane 40 may be made of porous PTFE, and the pores in the pressure buffer membrane 40 are preferably smaller in size than the pores in the filter 20. The pressure buffer film 40 may be formed to a thickness of about 10 to 1000 μm, and the pores of the pressure buffer film 40 may be formed to a diameter of about 0.1 to 10 μm.

A non-thick diffusion barrier 50 having a thin thickness t is disposed below the pressure buffer film 40. The non-porous diffusion barrier 50 may be made of FEP (tetrafluoroethylene-perfluoropropylene) without pores, and gas may have a property that the electrolyte 90 that permeates does not permeate. In addition, the non-porous diffusion barrier 50 serves to control the amount of oxygen gas participating in the reduction reaction in the cathode (70).

An o-ring 30 interposed between the non-porous diffusion barrier 50 and the upper housing 10a along the edge of the pressure buffer film 40 is an electrolyte 90 together with the non-porous diffusion barrier 50. The housing 10 serves to prevent the outflow to the outside.

Below the non-porous diffusion barrier 50, a cathode 60 in which a reduction reaction with oxygen occurs is formed. As the cathode 60, a material having catalytic properties for the reduction reaction of oxygen such as platinum black, platinum, gold, silver, or the like may be used. For example, PTFE powder may be mixed with a powder material made of platinum black or the like, and the cathode 60 may be formed by screen printing or compression coating on the non-porous diffusion barrier 50. In addition, a material such as platinum, gold, silver, or the like may be formed by sputtering or evaporating the non-porous diffusion barrier 50 to form the cathode 60.

The amount of oxygen reduced in the cathode 60 is proportional to the diffusion rate of oxygen passing through the non-porous diffusion barrier 50, and the diffusion rate of oxygen is proportional to the partial pressure difference of oxygen across the non-porous diffusion barrier 50. . Therefore, substantially the amount of oxygen reduced in the cathode 60, that is, the output value from the output terminal 112 is proportional to the partial pressure of the external oxygen. Therefore, the output value and the oxygen concentration in the hybrid oxygen gas sensor 100 have a linear proportional relationship as follows.

Sensor output = k × C

Where k is the proportionality constant and C is the concentration fraction of oxygen.

As described above, when the oxygen concentration is measured using the non-porous diffusion barrier 50, a linear output value can be obtained for the entire range (0 to 100%) of the oxygen concentration.

Furthermore, in order to obtain structural stability while improving the diffusion rate of oxygen with respect to the non-porous diffusion barrier 50, the thickness t of the non-porous diffusion barrier 50 is preferably about 1 to 50 μm.

Below the cathode 60, an ion collector 80 for measuring the ion current by the reduction reaction of the cathode 60 and the oxidation reaction of the anode 65 is disposed, and the ion collector 80 is a printed circuit. It is electrically connected to the substrate 110. The portion of the ion collector 80 adjacent to the cathode 60 has a disk shape having one or more openings 82 formed at the center thereof so that the cathode 60 and the electrolyte 90 may contact each other.

Below the ion collector 80, an upper isolation membrane 70 is disposed to prevent the electrolyte solution 90 from flowing upward. The upper separator 70 has an annular shape such that the opening 82 of the ion collector 80 can be exposed to the electrolyte 90. In addition, the upper isolation layer 70 is coupled to the locking fixing portion 14 formed at least one inside the upper portion of the upper housing 10a. That is, the locking hole 71 into which the locking fixing part 14 is inserted is formed in the upper isolation layer 70. The upper separator 70 and the O-ring 30 physically compress the non-porous diffusion barrier 50, the cathode 60, and the ion collector 80 interposed therebetween to allow the electrolyte 90 to flow out. It serves to prevent. The upper separator 70, the upper housing 10a, and the locking fixture 14 may be made of substantially the same material, and may be combined by ultrasonic fusion or thermal fusion.

Under the upper separator 70, the electrolyte 90, in which metal oxides generated by the oxidation of the anode 65 are dissolved, and the electrolyte 90 are absorbed under the upper separator 70 to absorb evaporation of the electrolyte 90. And an electrolyte receiving layer 92 which prevents electrical short between the cathode 60 and the anode 65. Under the electrolyte 90, a lower isolation layer 72 is formed to prevent the electrolyte 90 from flowing out. The printed circuit board 110 is disposed below the lower separator 72, and the anode 65 connected to the printed circuit board 110 passes through the lower separator 72 and is disposed in the electrolyte receiving layer 92. The lower separator 72 and the upper housing 10a may be made of substantially the same material, and may be combined by ultrasonic fusion or thermal fusion.

Examples of the electrolyte 90 include organic acids such as formic acid, acetic acid, propionic acid, n-butyric acid, maleic acid, and glutamic acid. Mixtures of these organic acid salts, wherein the salts include Li, K, Na, and the like can be used. Here, the organic acid serves to dissolve PbO formed through the reaction on the surface of the Pb electrode, which is the anode 65, and the organic acid salt increases the ion conductivity of the electrolyte so that the reaction can be made quickly and smoothly. As such, the electrolyte 90 composed of a mixture of organic acids and organic acid salts has a high solubility in PbO, thereby maximizing the life of the hybrid oxygen gas sensor 100.

The electrolyte receiving layer 92 is in close contact with each surface of the ion collector 80 and the anode 65 to facilitate the movement of ions between the ion collector 80 and the anode 65, and the absorption rate of the electrolyte 90 The high may be made of a porous polymer sponge that does not react with the electrolyte (90).

The anode 65 may be made of a material such as lead (Pb), and may be made of a plate shape, metal wire, or sintered metal powder to increase the surface area.

The printed circuit board 110 may include a thermistor capable of correcting the change in the output signal according to the resistance and the temperature to increase the stability of the output signal by reducing the change in the output signal due to the change in the internal resistance. The signal input portion of the printed circuit board 110 is connected to the ion collector 80 and the anode 65, and the signal output portion is connected to the output terminal 112.

According to the hybrid oxygen gas sensor 100 having such a structure, it is possible to increase the diffusion rate of oxygen passing through the non-porous diffusion barrier 50 having a thin thickness to increase the response speed in the cathode 60, and to provide a small hole. By using the oxygen inlet capillary 12 and the pressure buffer film 40 can be prevented from damage to the non-porous diffusion preventing film 50 due to a sudden external pressure change.

Hereinafter, the characteristics of the hybrid oxygen gas sensor according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3 to 5. 3 is a graph measuring the output signal according to the oxygen concentration in the hybrid oxygen gas sensor according to an embodiment of the present invention, Figure 4 is a flow of time in the hybrid oxygen gas sensor according to an embodiment of the present invention 5 is a graph measuring an output signal, and FIG. 5 is a graph measuring a response speed of a hybrid oxygen gas sensor according to an exemplary embodiment.

First, as shown in FIG. 3, it can be seen that the output signal of the hybrid oxygen gas sensor increases linearly as the oxygen concentration increases. Therefore, the oxygen concentration can be measured accurately.

Referring to FIG. 4, it can be seen that the output signal is constantly measured over time with respect to a specific oxygen concentration, and the output signal linearly increases over the entire range (0 to 100%) of the oxygen concentration.

Referring to the response time of the hybrid oxygen gas sensor with reference to Figure 5, once the change in the oxygen concentration is very closely related to the safety of the operator, it is very important to apply as a safety device to detect as soon as possible. 5 is a graph measuring response time when the space in which the hybrid oxygen gas sensor is placed is changed from 0% to 20.9% oxygen concentration. As shown in FIG. 5, the time at which 90% of the output signal value corresponding to the changed concentration was output was measured within about 10 seconds, and it can be seen that the response characteristic is very fast in response to the change in the external oxygen concentration.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments but may be manufactured in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, according to the hybrid oxygen gas sensor according to the present invention, by increasing the diffusion rate of oxygen passing through the thin non-porous diffusion barrier, the response speed in the cathode can be increased, and oxygen inflow composed of small holes The capillary tube and the pressure buffer film can be used to prevent damage to the non-porous diffusion barrier due to a sudden external pressure change.

Claims (7)

A housing in which a capillary tube for oxygen inflow having a diameter of 0.1 to 1 mm is formed; A porous pressure buffer membrane positioned below the oxygen inlet capillary in the housing to buffer an external pressure change; A non-porous diffusion barrier layer having a thickness of 1 to 50 μm, blocking electrolyte solution, permeating only gas components, and controlling the amount of oxygen gas participating in a reduction reaction, and located below the pressure buffer layer; A cathode located below said non-porous diffusion barrier; An electrolyte receiving layer under the cathode and filled with the electrolyte; And And an anode facing the cathode with the electrolyte receiving layer therebetween. According to claim 1, Further comprising an upper separator and a lower separator respectively disposed on the upper and lower portions of the electrolyte receiving layer, And the upper separator has an annular shape that exposes at least a portion of the cathode and is coupled to a locking fixture formed inside the upper portion of the housing. The method of claim 2, And an ion collector disposed between the cathode and the upper separator and having an opening formed in the center thereof. And the ion collector has a disk shape in which at least one opening is formed to allow the cathode and the electrolyte to contact each other. The method of claim 3, wherein O-ring interposed between the non-porous diffusion barrier and the housing along the edge of the pressure buffer film, And the O-ring and the upper separator physically compress the non-porous diffusion barrier, the cathode and the ion collector interposed therebetween. According to claim 1, The non-porous diffusion barrier is a hybrid oxygen gas sensor made of FEP. According to claim 1, The pores formed in the porous pressure buffer membrane has a diameter of about 0.1 to 10㎛ hybrid oxygen gas sensor. According to claim 1, The electrolyte solution is a hybrid oxygen gas sensor which is a mixed liquid of an organic acid consisting of formic acid, acetic acid, propionic acid, n-butyric acid, maleic acid and glutamic acid, and salts thereof.

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