WO2007066891A1 - Carbon dioxide sensing packaging apparatus comprising carbon dioxide sensor, carbon dioxide sensor module and electrical circuit board - Google Patents

Carbon dioxide sensing packaging apparatus comprising carbon dioxide sensor, carbon dioxide sensor module and electrical circuit board Download PDF

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Publication number
WO2007066891A1
WO2007066891A1 PCT/KR2006/004309 KR2006004309W WO2007066891A1 WO 2007066891 A1 WO2007066891 A1 WO 2007066891A1 KR 2006004309 W KR2006004309 W KR 2006004309W WO 2007066891 A1 WO2007066891 A1 WO 2007066891A1
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Prior art keywords
sensor
carbon dioxide
sensor module
heater
circuit board
Prior art date
Application number
PCT/KR2006/004309
Other languages
French (fr)
Inventor
Chong Ook Park
Jun-Woong Kim
Jang Soo Moon
Original Assignee
Korea Advanced Institute Of Science And Technology
Cios Inc.
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Publication date
Application filed by Korea Advanced Institute Of Science And Technology, Cios Inc. filed Critical Korea Advanced Institute Of Science And Technology
Publication of WO2007066891A1 publication Critical patent/WO2007066891A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4073—Composition or fabrication of the solid electrolyte
    • G01N27/4074—Composition or fabrication of the solid electrolyte for detection of gases other than oxygen
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/406—Cells and probes with solid electrolytes
    • G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
    • G01N27/4075—Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/004—CO or CO2

Definitions

  • This invention relates a carbon dioxide sensor and a module with the carbon dioxide sensor, and particularly, to a new structure of packaging the carbon dioxide sensor module adopting solid electrolyte, the sensor, a support, a heater and an outer cover to form a sensor assembly, which is designed for the sensor to be easily installed to and removed from the sensor assembly.
  • Carbon dioxide as a by-product of the combustion of fossil fuel becomes environmentally and industrially important because it is not only one of the main source of global warming to give a green house effects but also it can help the growth of the plant by managing the respiration of the plants through the control of CARBON DIOXIDE concentration in the ambient .
  • an optical absorption method has been conventionally used to measure the concentration of carbon dioxide in the ambient.
  • CARBON DIOXIDE absorbs only infrared rays having a specific wave length
  • the concentration of carbon dioxide can be measured just by measuring the amount of absorption of the corresponding wave length of the light.
  • This method offers excellent selectivity and reproducibility as well as relatively good accuracy.
  • it is generally bulky and expensive for an accurate measurement due to the need of large light-absorption chamber and many sophisticated optical filters and parts, which limits the application of the NDIR-carbon dioxide meter in the field.
  • the optical parts like window are vulnerable to be damaged when it is exposed to the hostile environments of outdoor. Therefore its use is mainly found in the indoors.
  • Another way of detecting carbon dioxide is to use semiconducting oxide ceramics such as tin oxide and titanium oxide as a resistor, because the adsorption of CARBON DIOXIDE on the surface of the oxide induces a change in resulting resistance of the ceramics depending on the amount of the carbon dioxide in the ambient. It has an advantage of small size, simple electronic circuits and cheap price but it is hard to find selectiveness due to a random character of the adsorption of gases on the surface.
  • the electrochemical sensor of solid electrolyte type has many merits of simple structure, small size, cheap price and excellent selectivity by using a sensor which can detect only specific gas. Furthermore, because it is composed of oxide ceramics, it can stand harsh environments of outdoors.
  • an object of the present invention is to provide a new structure of the bulk type carbon dioxide sensor with a new packaging of heater which guarantees the long term operation of the sensor, and a easily replaceable circuit board (sensor module) containing the sensor assembly, temperature sensor and the memory chip.
  • Another object of the present invention is to provide a new structure of packaging the bulk type carbon dioxide sensor with its support and heater, and the concept and the contents of the parts contained in the easy-replaceable sensor-imbedded circuit module.
  • This invention relates to a new structure of the sensor assembly containing new structured bulk type carbon dioxide sensor, its support and heater, and the concept and the packaging method of the parts contained in the easy- replaceable sensor-imbedded circuit module.
  • the carbon dioxide meter of this invention consists of the bulk type electrochemical carbon dioxide sensor, its support to hold the thermocouple in contact with the sensor, heater to heat the sensor up to the operating temperature and sensor module containing the sensor assembly.
  • Figs. Ia and Ib are views showing a structure of an electrochemical carbon dioxide sensor, and a photo of the electrochemical carbon dioxide sensor;
  • Fig. 2 is a view showing a schematic structure of the sensor support according to the invention.
  • Fig. 3 is a view showing a schematic structure of the heater according to the invention.
  • Fig. 4 is a graph showing change of the power consumption and the temperature with the voltage applied to the heater according to the invention.
  • Fig. 5 is a graph showing a time to reach an operating temperature of the heater according to the invention.
  • Figs, ⁇ a and ⁇ b are views showing a structure of the heater and a heater pedestal, and a photo thereof according to the invention
  • Figs. 7a and 7b are views showing a shape of the sensor assembly with an outer cover, and a Photo of the sensor assembly according to the invention
  • Fig. 8 is a graph showing the comparison of performance of the sensor with zeolite filler with the one without zeolite filler;
  • Figs. 9a and 9b are views showing a schematic structure of the sensor-imbedded circuit module (sensor module) equipped with the sensor assembly, and a photo of the sensor module disposed at a lower side of the outer cover according to the invention.
  • Fig. 10 is a graph showing long term stability of the carbon dioxide sensor of this invention.
  • the electrochemical carbon dioxide sensor has a
  • Galvanic structure where the voltage measured from the two electrodes deposited on both sides of the electrolytes gives an EMF which is logarithmically dependent on the concentration of carbon dioxide in the ambient (Nernst equation).
  • the electrochemical sensor of this invention composes of the reference electrode formed on one side of the electrolytes, the sensing electrode formed on the other side of the electrode, the filter cap which cover the sensing electrode, and the a pair of lead wires which is connected to the sensing and reference electrode as shown in Fig. 1.
  • the electrolytes mentioned above can be sodium ion (Na + ) conductors such as NASICON (Na 3 Zr 2 Si 2 POi 2 ) and beta-alumina ( ⁇ - alumina, Na 2 ODAIaO 3 ) etc. and the lead wires can be made of gold or Pt and the reference electrode is composed of a mixture of Na 2 Ti 6 Oi 3 and TiO 2 , whereas the sensing electrode is a salt containing Na 2 CO 3 such as a mixture of Na 2 CO 3 and BaCO 3 .
  • the electrochemical sensor as an essential part of this invention is vulnerable to the humid and other interfering gases in the environment, which results in an error in the measurement-reading.
  • the filter cap is introduced as shown in Fig. l(a) .
  • the filter cap above is designed to encapsulate the sensing layer as a porous ceramics containing sodium component, which enable the gases in the ambient to penetrate with ease and maintain a constant sodium environment.
  • the interface of the filter cap and the electrolyte is hermetically sealed with special sealant.
  • the filter cap with the bulk type sensor provide a long term stability of the sensor as well as to minimize the interference effects from the outside.
  • Fig. Ib shows the photo of the electrochemical sensor manufactured as mentioned above.
  • the sensor support for the bulk type electrochemical sensor of the above invention is designed such that it give a further stability in the operation and in the treatment during the manufacturing process as shown in Fig. 2. It composes of the same material with the electrolytes of the sensor and can be separated into two parts where the sensor is located in the middle.
  • the lead wire for the sensor is connected to the outside along the longitude of the support.
  • the thermocouple In contact with the sensor, the thermocouple resides to measure and control the temperature of the sensor and the thermocouple lead wire is longitudinally taken to the outside of the support to connect to the measuring instrument.
  • the two parts of the support is sealed with the ceramic bond after the sensor and the thermocouple is safely installed inside of the support. In order to operate the sensor, it has to be heated to a certain temperature of about 400-500 0 C, for which the cylindrical tube wound with heating coil is designed as shown in Fig. 3.
  • the temperature-read from the thermocouple is different from the real temperature of the sensor such that it gives an error in the measurement as well as an overheating of the sensor which can result in a permanent damage of the sensor.
  • the sensor with support gives a better reproducibility and longer life time than the one without it.
  • the heater is made of high purity alumina (>99.9%) tube with a diameter of 2.5cm and it is wound more than 20 times with a Kanthal heating coil (the alloy of Fe, Cr, Al, and Co). In order to give a uniform temperature throughout the sensor, the heater is covered with another alumina cylinder with a thickness of lmm.
  • the sensor assembly of this invention consists of the heater pedestal on which heater containing the sensor and the sensor support rests and the outer cover which encapsulates the heater to separate it from the outside as shown in Figs. 6 and 7.
  • the outer cover plays a role of reducing power consumption and helping to improve the stability of the sensor.
  • the outer cover is made of porous alumina or mullite(3Al 2 0 3 D2Si ⁇ 2 ) which can stand the heat of 300-500 0 C emanating from the heater and maintain a constant temperature of the sensor with changing the environmental temperature.
  • the heater pedestal is shown in Figs. 6 (a) and (b) where 6 pins are taken from the sensor: 2 pins from the heater, 2 pins from the thermocouple and 2 pins from the sensor itself. These pins are fixed to the pedestal using ceramic bond.
  • the heater pedestal is covered and sealed with the outer cover as shown in Figs. 7a and b and the space inside is packed with zeolite or silica gel to prevent from the interferences of humidity and other gases.
  • These packing materials help to reduce the time to reach a stabilization of the sensor. For example, it is shown in Fig. 8 for the zeolite powder as a packing material.
  • a circuit board to place a sensor assembly. 6 pins from the heater pedestal are connected to the 6 pins of PCB circuit board to form a sensor module as shown in Figs. 9a and b.
  • the above sensor module designed for an easy-attachment and easy-detachment equips with memory devices such as EEPROM which contains data on the sensor like the sensor engagement time, sensitivity value, and sensor constant as well as the temperature sensor to compensate the temperature of the sensor.
  • Figure 10 shows the long-term stability performance of the such-made prototype carbon dioxide meter equipped with the above sensor assembly. The EMF reading when it is operated at 7V with 16W power gives a stable value over 250 days.
  • the bulk type electrochemical carbon dioxide sensor of this invention exhibits superior performance in terms of its stability and life time to the conventional electrochemical carbon dioxide meter mainly because it adopts new packaging structure of the sensor assembly having a filter cap in sensor, sensor support, heater and PCB circuit board with memory chip and temperature sensor.
  • it has an easy-detachment and easy-attachment scheme such that user as an inexpert in the analytical instruments can easily install or replace the old sensor with a new part without a difficult calibration process.
  • the system reads automatically the data of the corresponding sensor stored in the memory chip in the sensor module to set up and calibrate the algorithm of the measurement.
  • the optimum structure of the heater also makes the temperature of the sensor stable irrespective of the environment, which helps the stability and the life time of the sensor.

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Abstract

This invention is about the new method of packaging the electrochemical carbon dioxide sensor and its concept of sensor-imbedded module as a replaceable part which contains the memory chip and the temperature sensor as a temperature compensation elements on the circuit board. The module consists of the electrochemical carbon dioxide sensor assembly containing the solid electrolyte carbon dioxide sensor, sensor support, heating element and cover, and the easily replaceable circuit board containing the memory chip and the temperature sensor.

Description

CARBON DIOXIDE SENSING PACKAGING APPARATUS COMPRISING CARBON DIOXIDE SENSOR, CARBON DIOXIDE SENSOR MODULE AND ELECTRICAL
CIRCUIT BOARD
[Technical Field]
This invention relates a carbon dioxide sensor and a module with the carbon dioxide sensor, and particularly, to a new structure of packaging the carbon dioxide sensor module adopting solid electrolyte, the sensor, a support, a heater and an outer cover to form a sensor assembly, which is designed for the sensor to be easily installed to and removed from the sensor assembly.
[Background Art] Carbon dioxide as a by-product of the combustion of fossil fuel becomes environmentally and industrially important because it is not only one of the main source of global warming to give a green house effects but also it can help the growth of the plant by managing the respiration of the plants through the control of CARBON DIOXIDE concentration in the ambient .
So far, an optical absorption method (NDIR) has been conventionally used to measure the concentration of carbon dioxide in the ambient. Because CARBON DIOXIDE absorbs only infrared rays having a specific wave length, the concentration of carbon dioxide can be measured just by measuring the amount of absorption of the corresponding wave length of the light. This method offers excellent selectivity and reproducibility as well as relatively good accuracy. However it is generally bulky and expensive for an accurate measurement due to the need of large light-absorption chamber and many sophisticated optical filters and parts, which limits the application of the NDIR-carbon dioxide meter in the field. Especially the optical parts like window are vulnerable to be damaged when it is exposed to the hostile environments of outdoor. Therefore its use is mainly found in the indoors.
Another way of detecting carbon dioxide is to use semiconducting oxide ceramics such as tin oxide and titanium oxide as a resistor, because the adsorption of CARBON DIOXIDE on the surface of the oxide induces a change in resulting resistance of the ceramics depending on the amount of the carbon dioxide in the ambient. It has an advantage of small size, simple electronic circuits and cheap price but it is hard to find selectiveness due to a random character of the adsorption of gases on the surface.
As an alternative way of detecting carbon dioxide, the electrochemical sensor of solid electrolyte type has many merits of simple structure, small size, cheap price and excellent selectivity by using a sensor which can detect only specific gas. Furthermore, because it is composed of oxide ceramics, it can stand harsh environments of outdoors. The study on the carbon dioxide sensor mentioned above had been first studied by Gauthier and Chamberland in 1970s. They used a potassium carbonate as a sensing material. From that on, many researchers devoted their efforts to the development of electromotive carbon dioxide sensors, combining various solid electrolytes such as NASICON, LISICON and beta alumina (NBA) . But these methods were lack of stability mainly because of the gradual chemical reactions with the carbon dioxide gas occurring at the sensing material. Therefore it is known in the market as having a short life time and needing periodic calibrations to compensate for the degradation of the output of the sensor. For example, in case of a carbon dioxide sensor using the NASICON developed and come out by Figaro corp. located in Japan, since a signal from the sensor is constantly changed with the lapse of time, there is a technical problem that it should be compensated every day.
[Disclosure] [Technical Problem] In order to overcome the conventional stability problem of the carbon dioxide sensor, especially in the thick film type sensors, an object of the present invention is to provide a new structure of the bulk type carbon dioxide sensor with a new packaging of heater which guarantees the long term operation of the sensor, and a easily replaceable circuit board (sensor module) containing the sensor assembly, temperature sensor and the memory chip.
Another object of the present invention is to provide a new structure of packaging the bulk type carbon dioxide sensor with its support and heater, and the concept and the contents of the parts contained in the easy-replaceable sensor-imbedded circuit module.
[Technical Solution]
This invention relates to a new structure of the sensor assembly containing new structured bulk type carbon dioxide sensor, its support and heater, and the concept and the packaging method of the parts contained in the easy- replaceable sensor-imbedded circuit module.
The carbon dioxide meter of this invention consists of the bulk type electrochemical carbon dioxide sensor, its support to hold the thermocouple in contact with the sensor, heater to heat the sensor up to the operating temperature and sensor module containing the sensor assembly.
[Description of Drawings]
Figs. Ia and Ib are views showing a structure of an electrochemical carbon dioxide sensor, and a photo of the electrochemical carbon dioxide sensor; Fig. 2 is a view showing a schematic structure of the sensor support according to the invention;
Fig. 3 is a view showing a schematic structure of the heater according to the invention; Fig. 4 is a graph showing change of the power consumption and the temperature with the voltage applied to the heater according to the invention;
Fig. 5 is a graph showing a time to reach an operating temperature of the heater according to the invention;
Figs, βa and βb are views showing a structure of the heater and a heater pedestal, and a photo thereof according to the invention;
Figs. 7a and 7b are views showing a shape of the sensor assembly with an outer cover, and a Photo of the sensor assembly according to the invention; Fig. 8 is a graph showing the comparison of performance of the sensor with zeolite filler with the one without zeolite filler;
Figs. 9a and 9b are views showing a schematic structure of the sensor-imbedded circuit module (sensor module) equipped with the sensor assembly, and a photo of the sensor module disposed at a lower side of the outer cover according to the invention; and
Fig. 10 is a graph showing long term stability of the carbon dioxide sensor of this invention.
[Mode for Invention]
Following is the detailed description of the invention;
In general, the electrochemical carbon dioxide sensor has a
Galvanic structure where the voltage measured from the two electrodes deposited on both sides of the electrolytes gives an EMF which is logarithmically dependent on the concentration of carbon dioxide in the ambient (Nernst equation).
The electrochemical sensor of this invention composes of the reference electrode formed on one side of the electrolytes, the sensing electrode formed on the other side of the electrode, the filter cap which cover the sensing electrode, and the a pair of lead wires which is connected to the sensing and reference electrode as shown in Fig. 1.
The electrolytes mentioned above can be sodium ion (Na+) conductors such as NASICON (Na3Zr2Si2POi2) and beta-alumina (β- alumina, Na2ODAIaO3) etc. and the lead wires can be made of gold or Pt and the reference electrode is composed of a mixture of Na2Ti6Oi3 and TiO2, whereas the sensing electrode is a salt containing Na2CO3 such as a mixture of Na2CO3 and BaCO3. The electrochemical sensor as an essential part of this invention is vulnerable to the humid and other interfering gases in the environment, which results in an error in the measurement-reading. Furthermore, the evaporation of the sodium component from the sensing material can be a reason of degradation of the sensor which gives a permanent damage and stability problem. In order to prevent from the evaporation of sodium component and the interfering gases, the filter cap is introduced as shown in Fig. l(a) . The filter cap above is designed to encapsulate the sensing layer as a porous ceramics containing sodium component, which enable the gases in the ambient to penetrate with ease and maintain a constant sodium environment. In addition, the interface of the filter cap and the electrolyte is hermetically sealed with special sealant. The filter cap with the bulk type sensor provide a long term stability of the sensor as well as to minimize the interference effects from the outside. Fig. Ib shows the photo of the electrochemical sensor manufactured as mentioned above. The sensor support for the bulk type electrochemical sensor of the above invention is designed such that it give a further stability in the operation and in the treatment during the manufacturing process as shown in Fig. 2. It composes of the same material with the electrolytes of the sensor and can be separated into two parts where the sensor is located in the middle. The lead wire for the sensor is connected to the outside along the longitude of the support. In contact with the sensor, the thermocouple resides to measure and control the temperature of the sensor and the thermocouple lead wire is longitudinally taken to the outside of the support to connect to the measuring instrument. The two parts of the support is sealed with the ceramic bond after the sensor and the thermocouple is safely installed inside of the support. In order to operate the sensor, it has to be heated to a certain temperature of about 400-5000C, for which the cylindrical tube wound with heating coil is designed as shown in Fig. 3.
Without sensor support, the temperature-read from the thermocouple is different from the real temperature of the sensor such that it gives an error in the measurement as well as an overheating of the sensor which can result in a permanent damage of the sensor. As a result, the sensor with support gives a better reproducibility and longer life time than the one without it.
The heater is made of high purity alumina (>99.9%) tube with a diameter of 2.5cm and it is wound more than 20 times with a Kanthal heating coil (the alloy of Fe, Cr, Al, and Co). In order to give a uniform temperature throughout the sensor, the heater is covered with another alumina cylinder with a thickness of lmm. It needs 7.8V-2.9A for the above heater to reach an operating temperature of 5000C, which corresponds to a power consumption of 2OW as shown in Fig. 4. And it takes about 15 minutes to reach 5000C as shown in Fig. 5.
The sensor assembly of this invention consists of the heater pedestal on which heater containing the sensor and the sensor support rests and the outer cover which encapsulates the heater to separate it from the outside as shown in Figs. 6 and 7. The outer cover plays a role of reducing power consumption and helping to improve the stability of the sensor. The outer cover is made of porous alumina or mullite(3Al203D2Siθ2) which can stand the heat of 300-500 0C emanating from the heater and maintain a constant temperature of the sensor with changing the environmental temperature. The heater pedestal is shown in Figs. 6 (a) and (b) where 6 pins are taken from the sensor: 2 pins from the heater, 2 pins from the thermocouple and 2 pins from the sensor itself. These pins are fixed to the pedestal using ceramic bond. The heater pedestal is covered and sealed with the outer cover as shown in Figs. 7a and b and the space inside is packed with zeolite or silica gel to prevent from the interferences of humidity and other gases. These packing materials help to reduce the time to reach a stabilization of the sensor. For example, it is shown in Fig. 8 for the zeolite powder as a packing material. In addition, in order to connect the sensor assembly to the main body conveniently, we devise a circuit board (sensor module) to place a sensor assembly. 6 pins from the heater pedestal are connected to the 6 pins of PCB circuit board to form a sensor module as shown in Figs. 9a and b. The above sensor module designed for an easy-attachment and easy-detachment equips with memory devices such as EEPROM which contains data on the sensor like the sensor engagement time, sensitivity value, and sensor constant as well as the temperature sensor to compensate the temperature of the sensor. Figure 10 shows the long-term stability performance of the such-made prototype carbon dioxide meter equipped with the above sensor assembly. The EMF reading when it is operated at 7V with 16W power gives a stable value over 250 days.
[industrial Applicability]
The bulk type electrochemical carbon dioxide sensor of this invention exhibits superior performance in terms of its stability and life time to the conventional electrochemical carbon dioxide meter mainly because it adopts new packaging structure of the sensor assembly having a filter cap in sensor, sensor support, heater and PCB circuit board with memory chip and temperature sensor. In addition, it has an easy-detachment and easy-attachment scheme such that user as an inexpert in the analytical instruments can easily install or replace the old sensor with a new part without a difficult calibration process. When the sensor is installed, the system reads automatically the data of the corresponding sensor stored in the memory chip in the sensor module to set up and calibrate the algorithm of the measurement. The optimum structure of the heater also makes the temperature of the sensor stable irrespective of the environment, which helps the stability and the life time of the sensor.

Claims

[Claims] [Claim l]
An electrochemical carbon dioxide sensor, comprising: a solid electrode; a reference electrode and a sensing electrode formed in the said solid electrode; a filter cap enclosing the said sensing electrode or the said reference electrode or the both; and a pair of thermocouple lead wires which are respectively connected to and are extended from the said sensing electrode and the said reference electrode.
[Claim 2]
The sensor according to Claim 1, further comprising a sealing layer in contact with the filter cap or with the solid electrolyte or with the both.
[Claim 3]
The sensor according to Claim 1 or Claim 2, wherein the said filter cap is made of porous ceramics material.
[Claim 4] An electrochemical carbon dioxide sensor module, comprising: an electrochemical carbon dioxide sensor according to any one of Claim 1 to Claim 3; and a sensor support that fixes the electrochemical carbon dioxide sensor. [Claim 5]
The sensor module according to Claim 4, wherein the said sensor support is made of porous ceramics material which can be separated into more than two pieces.
[Claim βl The sensor module according to Claim 5, wherein the said sensor support has a thermocouple, and a pair of thermocouple lead wire inside the electrochemical carbon dioxide sensor to measure and control temperature and voltage of the sensor.
[Claim 7] The sensor module according to Claim 6, wherein the said thermocouple lead wire and the said voltage-reading lead wire is extended outside of the said sensor support.
[Claim 8]
The sensor module according to any one of Claim 5 to 7, further comprising a heater formed with a hollow portion for receiving the sensor support, and a heating coil disposed at an outside thereof.
[Claim 9]
The sensor module according to Claim 8, wherein the said heater has a cylindrical shaped ceramic tube and a heating coil wrapped around the said tube with a constant distance.
[Claim 10]
The sensor module according to Claim 9, wherein the said heater has another cylindrical alumina tube having a thickness of lmm which covers intimately over the heating coil.
[Claim 11]
The sensor module according to Claim 9, wherein the electrochemical carbon dioxide sensor module has a packaging structure in which a heater pedestal on which the heater containing the carbon dioxide sensor and the sensor support rests and the outer cover which encapsulates the heater to separate it from the outside is placed.
[Claim 12]
The sensor module according to Claim 11, wherein dehumidifying powder is filled in the said outer cover.
[Claim 13]
A circuit board which can be easily detachable, as a part, from a main circuit board so as to be electrically connected with a lower side of the support of the outer cover according to Claim 4.
[Claim 14]
The circuit board according to Claim 13, further comprising a memory chip for storing data of a carbon dioxide sensor.
[Claim 15] The circuit board according to Claim 13 and 14, further comprising a temperature circuit and sensor to compensate a temperature of the sensor.
PCT/KR2006/004309 2005-10-31 2006-10-23 Carbon dioxide sensing packaging apparatus comprising carbon dioxide sensor, carbon dioxide sensor module and electrical circuit board WO2007066891A1 (en)

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KR1020050102891A KR20070046327A (en) 2005-10-31 2005-10-31 Carbon dioxide sensing packaging apparatus comprising carbon dioxide sensor, carbon dioxide sensor module and electrical circuit board
KR10-2005-0102891 2005-10-31

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109752036A (en) * 2019-03-05 2019-05-14 河南艾牧智能设备有限公司 A kind of dust-proof anti-condensation sensor

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