CN1077687C - Hydrocarbon gas sensor and its producing method - Google Patents
Hydrocarbon gas sensor and its producing method Download PDFInfo
- Publication number
- CN1077687C CN1077687C CN97119278.2A CN97119278A CN1077687C CN 1077687 C CN1077687 C CN 1077687C CN 97119278 A CN97119278 A CN 97119278A CN 1077687 C CN1077687 C CN 1077687C
- Authority
- CN
- China
- Prior art keywords
- layer
- sensitive
- layers
- catalyst
- thickness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 86
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 86
- 239000004215 Carbon black (E152) Substances 0.000 title claims abstract description 81
- 238000000034 method Methods 0.000 title claims description 22
- 239000000758 substrate Substances 0.000 claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 claims abstract description 16
- 239000003054 catalyst Substances 0.000 claims description 53
- 238000001514 detection method Methods 0.000 claims description 25
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 20
- 239000000243 solution Substances 0.000 claims description 16
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 10
- -1 platinum (IV) hexachloride hydrate Chemical compound 0.000 claims description 10
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 10
- 239000011248 coating agent Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- NDBYXKQCPYUOMI-UHFFFAOYSA-N platinum(4+) Chemical compound [Pt+4] NDBYXKQCPYUOMI-UHFFFAOYSA-N 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 151
- 239000007789 gas Substances 0.000 description 134
- 239000004065 semiconductor Substances 0.000 description 19
- 230000035945 sensitivity Effects 0.000 description 11
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 9
- 229910002091 carbon monoxide Inorganic materials 0.000 description 9
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 230000003197 catalytic effect Effects 0.000 description 5
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- LJCFOYOSGPHIOO-UHFFFAOYSA-N antimony pentoxide Inorganic materials O=[Sb](=O)O[Sb](=O)=O LJCFOYOSGPHIOO-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910001260 Pt alloy Inorganic materials 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N SnO2 Inorganic materials O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 125000003158 alcohol group Chemical group 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000012858 packaging process Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Images
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
A kind of hydrocarbon gas sensing device and its manufacturing method. The sensing device includes a sensing layer for sensing only hydrocarbon gas is formed on an electrode formed on a substrate, and overcoating layers reacting with reducing gas are formed on the sensing layer. The reducing gas among various kinds of gas reacts with the overcoating layers and is removed, and only the hydrocarbon gas among remaining gas is sensed by the sensing layer and output via the electrode. Therein electode sensing layer and overcoating layers are formed by separated way each other, so that make testings more efficiently and selectively.
Description
The present invention relates to a multilayer hydrocarbon gas sensor and a method of manufacturing the same and a method of detecting hydrocarbons using the hydrocarbon gas sensor, and more particularly, to a multilayer hydrocarbon gas sensor selectively responding to different flammable gases and a method of manufacturing the same and a method of detecting hydrocarbons using the hydrocarbon gas sensor.
There are generally two types of gas sensors, one is a semiconductor-type or resistance-type gas sensor in which a semiconductor is used as a sensitive material, and the other is a pellistor-type gas sensor in which a catalyst such as palladium or platinum is used as a sensitive material. Semiconductor gas sensors are commonly used for detecting reducing gases such as carbon monoxide (CO), hydrogen and alcohols, and pellistor-type sensors are commonly used for detecting flammable gases such as LNG and LPG.
Fig. 1A and 1B schematically show a typical semiconductor-type gas sensor structure, fig. 1A showing a thick film-type gas sensor, and fig. 1B showing a tube-type gas sensor. As shown in the drawing, the thick film type gas sensor includes: a sensitive portion 3 having a heater 2 on one side of a substrate 1, the heater 2 constituting a main structure for heating the sensor to a predeterminedtemperature, an oxide semiconductor on the other side of the substrate and having a predetermined resistance value, an electrode 4 for guiding a signal detected by the sensitive portion 3 to an output side when a gas reacts with the sensitive portion 3, leads (not shown) leading to the heater 2 and the electrode 4, and packaging all of the above elements. The tube-type gas sensor includes: a tube 5 constituting a frame, a heater 6 for heating the sensor to a predetermined temperature, an oxide semiconductor sensitive portion 7 having a predetermined resistance value coated on an outer surface of the tube 5, an electrode 8 in contact with the sensitive portion 7 to guide a detection signal to an output side, and a lead wire 9 connected to the heater 6 and the electrode 8And 10. The wiring layout of the thick film type gas sensor shown in fig. 1A is shown in fig. 2A, which supplies power to the heater 2 and the sensitive part 3 and forms a detection circuit in which the sensitive part 3 and the resistor R are connected, respectively1Connected in series with a variable resistor VRO and connected with a resistor R2And (4) connecting in parallel.
In each of the above-described semiconductor-type gas sensors, oxygen ions (O) when adsorbed on the surface of the oxide semiconductor sensitive portion 3-Or O2-) When the sensor is brought into contact with a reducing gas in a state where the sensor is heated to a predetermined temperature (e.g., 300 to 500 ℃) by the heater 2, these oxygen ions react according to the following chemical reaction equation and generate electrons
[ chemical equation 1]
O-＋R-RO＋e-Or O2-＋R-RO＋2e-
In this case, since the resistance of the oxide semiconductor sensitive portion 3 changes with a change in the electron concentration therein, which accompanies a change in the output signal of the detection circuit, the gas can be detected by detecting the changed electric signal of the output terminal.
Fig. 2B shows a detection circuit of one tube-type gas sensor in which the heater 2 and the sensitive part 3 in the thick film gas sensor are replaced with a heater 6 and a sensitive part 7 of the tube-type gas sensor, and since other components of the two sensors are the same except for the above-described parts, the same reference numerals are used, and the description thereof is omitted.
In the tube-type gas sensor, when the sensitive portion 7 is heated to, for example, 300 ℃ and 400 ℃ by the heater 6, oxygen ions (O) adsorbed on the surface of the sensitive portion 7 and in contact with the reducing gas R-Or O2-) A chemical reaction takes place and electrons are generated, and a change in the concentration of the electrons subsequently causes a change in the resistance of the sensitive part 7, which changes the signal of the detection circuit, thereby generating an electrical signal corresponding to the concentration of the detection gas.
Meanwhile, the pellistor type gas sensor includes a sensor with a catalyst and a reference cell without a catalyst, and if a combustible gas (e.g., LNG or LPG) is brought into contact with the surface of the sensing cell heated to about 300 ℃. 400 ℃, a combustion reaction occurs with a temperature rise, so that the current flowing through the heater of the sensing cell composed of a metal resistor (typically platinum or a platinum alloy) becomes smaller than the current flowing through the heater of the reference cell which does not generate a combustion reaction because the reference cell has no catalyst. The gas combustion heat generated along with the change of the current of the heater is detected to detect whether a certain concentration of gas exists.
However, the conventional semiconductor gas sensor has a disadvantage of generating a false alarm because the semiconductor gas sensor is sensitive to non-selected hydrocarbon gases, not only hydrocarbon gases, but also reducing gases such as carbon monoxide when it is operated, and in addition, the pellistor type gas sensor has a disadvantage of being inoperable at low concentrations of gases.
Accordingly, it is an object of the present invention to provide a hydrocarbon gas sensor and a method of manufacturing the same that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a hydrocarbon gas sensor capable of efficiently and selectively detecting a hydrocarbon gas mixed with gases of different properties, and a method of manufacturing the same.
Another object of the present invention is to provide a hydrocarbon gas sensor capable of selectively detecting only a low concentration of hydrocarbon gas among gases of different properties, and a method of manufacturing the same.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. These objects and other advantages of the invention are achieved and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, a hydrocarbon gas sensor is provided, including: a substrate; a heater under the substrate; a plurality of electrodes on an upper portion of the substrate; a sensitive layer formed on the electrode; an outer cover layer formed on the sensitive layer,
each electrode is provided with a corresponding sensitive layer which is only sensitive to hydrocarbon; an insulating layer is arranged above each sensitive layer to cover the sensitive layers; forming a catalyst layer on the insulating layer corresponding to each of the sensitive layers, the catalyst layers being spaced apart from each other; the outer cover layer includes an insulating layer and each catalyst layer, and the outer cover layer reacts with a reducing gas.
According to another aspect of the present invention, there is also provided a method of manufacturing a hydrocarbon gas sensor, including the steps of: providing a substrate; forming a heater on a lower portion of the substrate; forming a plurality of electrodes on an upper portion of a substrate; forming a sensitive layer which is only sensitive to hydrocarbon on each electrode; forming an insulating layer over all of the sensitive layers; a catalyst layer is formed on the insulating layer corresponding to each sensitive layer, the catalyst layers being spaced apart from each other, the insulating layer and each catalyst layer constituting an outer covering layer reacting with a reducing gas.
According to another aspect of the present invention, there is provided a method of detecting hydrocarbons using a hydrocarbon gas sensor including: a substrate; two electrodes on the substrate; a sensitive layer which is only sensitive to hydrocarbon is arranged on each electrode, so that a first sensitive layer and a second sensitive layer are formed; an insulating layer covers the two sensitive layers; forming a first catalyst layer and a second catalyst layer on the insulating layer corresponding to the first and second sensitive layers, the catalyst layers being spaced apart from each other, the insulating layer and the first catalyst layer forming a first outer capping layer, and the insulating layer and the second catalyst layer forming a second outer capping layer, the outer capping layers being reacted with a reducing gas;
the method comprises the following steps: comparing the voltages from the first sensitive layer and the second sensitive layer during detection with a preset first reference voltage and a preset second reference voltage respectively; if the voltage from the first sensing layer is greater than the first reference voltage, comparing the voltage from the second sensing layer with a predetermined second reference voltage, and if the voltage from the second sensing layer is less than the predetermined second reference voltage, determining that the detected gas is a hydrocarbon gas.
In the above-described hydrocarbon gas sensor of the present invention, when the hydrocarbon gas sensor is activated, before the gas reaches the oxide semiconductor under the blanket and is converted into an electric signal, since the reducing gas such as CO is chemically reacted with oxygen by the catalyst on the blanket to convert into CO2So that the contribution of the reducing gas in generating an electric signal is reduced, and only the hydrocarbon gas such as propane reaches the sensitive layer of the oxide semiconductor and reacts, thereby generating electrons that change the resistance of the sensitive portion, according to the electric signal from the electrodeThe electrical signal can selectively and accurately detect the hydrocarbon gas.
The advantages of the hydrocarbon gas sensor of the present invention are particularly reflected in: the sensor can selectively detect only hydrocarbon gas from different types of gases by providing a plurality of independent electrodes and sensing layers and forming an outer covering layer on each sensing layer.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
Fig. 1A shows a cross-sectional view of a conventional thick film type semiconductor gas sensor.
Fig. 1B shows a cross-sectional view of a conventional tube-type semiconductor gas sensor.
Fig. 2A to 2C show gas detection circuits of thick and thin type and tube type semiconductor gas sensors, respectively.
Fig. 3 shows a cross-sectional view of a hydrocarbon gas sensor according to a preferred embodiment of the present invention.
FIG. 4 illustrates the method steps for making a hydrocarbon gas sensor in accordance with a preferred embodiment of the present invention.
Fig. 5 shows a graph of the sensitivity of a hydrocarbon gas sensor to hydrocarbon gas and reducing gas in accordance with a preferred embodiment of the present invention.
Fig. 6A to 6C show a sectional view and a plan view of a hydrocarbon gas sensor with a plurality of electrodes according to a second embodiment of the present invention.
Fig. 7 shows a process for manufacturing a hydrocarbon gas sensor according to a preferred embodiment of the present invention.
Fig. 8 shows a detection circuit for a hydrocarbon gas sensor according to a preferred embodiment of the present invention.
Fig. 9shows a block diagram of a hydrocarbon gas sensor according to a preferred embodiment of the present invention.
Fig. 10 is a flowchart illustrating steps of a method for detecting hydrocarbon gas using a hydrocarbon gas detection device according to a preferred embodiment of the present invention.
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Fig. 3 shows a sectional view of a hydrocarbon gas sensor according to a first preferred embodiment of the present invention.
Referring to FIG. 3, the hydrocarbon gas sensor according to the first preferred embodiment of the present invention includes a heater 12 and electrodes 13 printed on both sides of a substrate 11 in a desired pattern, and a sensor electrode formed on the electrodes 13 with 5 to 10 wt% Zn added2O3，0.1～2.0wt％Sb2O5And 0.1 to 5.0 wt% Pd, 83.0 to 94.8 wt% SnO2A sensitive layer 14 of oxide semiconductor, an insulating layer 15 of silicon dioxide with a thickness of about 10-100 mu formed on the sensitive layer 14, a buffer layer 16 of silicon dioxide and palladium chloride with a thickness of about 10-50 mu formed on the insulating layer 15, and a conductive layer formed on the buffer layer 16A catalyst layer 17 made of palladium chloride and having a thickness of about 10 to 50 mu. The insulating layer 15, the buffer layer 16 and the catalyst layer 17, which are sequentially formed on the sensitive layer 14, constitute an outer cover layer. Although the outer cover layer includes the insulating layer 15, the buffer layer 16 and the catalyst layer 17 in the first embodiment, the catalyst layer 17 may be formed under the buffer layer 16 without the buffer layer 16The contact is formed on the insulating layer.
A method for manufacturing the above-described hydrocarbon gas sensor is explained below.
Fig. 4 shows steps of a method for manufacturing a hydrocarbon gas sensor according to a preferred embodiment of the present invention.
Referring to fig. 4, as a conventional example, the method starts with cleaning the substrate, and then printing electrodes and heaters in a predetermined pattern on both sides of the substrate, respectively, and performing heat treatment. Then adding 5-10 wt% of Zn2O3，0.1～2.0wt％Sb2O5And 83.0 to 94.8% SnO of 0.1 to 5.0 wt% Pd2The structured oxide semiconductor sensitive layer is screen-printed on the entire upper side of the substrate together with the electrodes and heat-treated in a temperature range of 400 to 800 ℃. Then the core step of the invention, the outer coating process, is completed. Firstly, coating a silica sol solution on a sensitive layer to form a coating with the thickness of 10-100 mu, drying at the temperature of 150 ℃, then carrying out heat treatment at the temperature of 600 ℃ to form an insulating layer, and mixing the silica sol solution with palladium chloride (PdCl) dissolved in the silica sol solution2) The mixture of ethanol (b) is coated on the insulating layer to form a coating layer having a thickness of about 10 to 50 mu, dried at a temperature of 150 ℃, and then subjected to a heat treatment at 600 ℃ to form a buffer layer. And coating the buffer layer with a palladium chloride ethanol solution with a coating thickness of 10-50 mu at the buffer layer, drying at 150 ℃, and then performing heat treatment at 600 ℃ to form a catalyst layer, thereby finishing the outer coating process. After completing the manufacture of a sensor element, leads are connected to package the element, thereby obtaining a sensor.
Inthe above-described hydrocarbon gas sensor of the present invention, when the heater 11 is heated to 300 to 500 ℃ by supplying power to the heater in order to excite the hydrocarbon gas sensor, before the gas reaches the oxide semiconductor under the outer cover layer and is converted into an electric signal, the reducing gas (e.g., CO) is converted into CO by a chemical reaction with oxygen as shown in the following chemical equation 2 by the palladium chloride catalyst in the outer cover layer2So that most of the reducing gas contributes less to the generation of the electric signal, only the hydrocarbon gas R (e.g., propane) reaches the sensitive layer 14 (oxide semiconductor), andand reacts with oxygen that has been adsorbed on the sensitive material, thereby generating electrons as shown in chemical equation 1
[ chemical equation 2]
As described above, when electrons are generated, the electrons flow through the variable resistor VRO and the resistance R because the resistance of the sensitive layer 14 decreases1Becomes large. Due to output signal, i.e. electricity at the output of the detection circuitThe pressure becomes large, so the detection circuit shown in fig. 2C can detect the hydrocarbon gas.
Fig. 5 shows sensitivity curves of the hydrocarbon gas sensor to the hydrocarbon gas and the reducing gas according to a preferred embodiment of the present invention, from which it can be seen that the sensitivity of the sensor to propane gas (O-500ppm) as a typical hydrocarbon gas is significantly higher than that of carbon monoxide gas (0 to 20000ppm) as a typical reducing gas, that is, the sensitivity of the sensor to the hydrocarbon gas is much higher than that of the reducing gas. In this case, the sensor resistance R used in airairWith resistanceR of the sensor in a gasgasThe ratio S of (a) represents the sensitivity.
Fig. 6A to 6C are a sectional view and a plan view of a hydrocarbon gas sensor with electrodes according to a second embodiment of the present invention, in which fig. 6A is a sectional view, fig. 6B is a plan view from above, and fig. 6C is a plan view from below. Fig. 7 shows a process of manufacturing a hydrocarbon gas sensor according to a preferred embodiment of the present invention, fig. 8 shows a gas detection circuit of the hydrocarbon gas sensor according to the preferred embodiment of the present invention, fig. 9 is a block diagram showing the hydrocarbon gas sensor according to the preferred embodiment of the present invention, and fig. 10 is a flowchart showing the method steps of detecting hydrocarbons using the hydrocarbon detection device according to the preferred embodiment of the present invention.
Referring to fig. 6A, a hydrocarbon gas sensor according to a second embodiment of the present invention includes: a substrate 21, a heater 22 printed on a lower portion of the substrate 21 in a pattern shown in fig. 6C, a first electrode 23 and a second electrode 24 formed on predetermined regions of an upper portion of the substrate 21 in a shape shown in fig. 6B, a first sensitive layer 25 formed on predetermined regions of the upper portion of the substrate 21 in conjunction with the first electrode 23, a second sensitive layer 26 formed on predetermined regions of the upper portion of the substrate 21 in conjunction with the second electrode 24, an insulating layer 27 formed on an entire surface of the substrate 21 in conjunction with the first and second sensitive layers 25 and 26, a first buffer layer 28 formed on the insulating layer 27 above the first sensitive layer 25, a first catalyst layer 30 formed on the insulating layer 27 above the second sensitive layer 26 spaced apart from the first buffer layer 28, and a second catalytic layer 31 formed on the second buffer layer 29. The insulating layer 27, the first buffer layer 28 and the first catalyst layer 30 on the first sensitive layer 25, and the insulating layer 27, the second buffer layer 29 and the second catalyst layer 31 on the second sensitive layer 26 each constitute an outer cover layer. The first buffer layer 28 and the second buffer layer 29 may be omitted as necessary. Although in this embodiment there are two electrodes spaced from each other, some electrodes may be added as required.
The above-described hydrocarbon gas sensor may be manufactured according to the process steps shown in fig. 7.
First, the substrate is cleaned, the heater 22 is printed in a predetermined pattern on the lower portion of the substrate 21, the first electrode 23 and the second electrode 24 are printed in predetermined regions on the upper portion of the substrate 21, and heat treatment is performed. Then, on the upper portion of the substrate 21 including the first and second electrodes 23 and 24, SnO is printed2And heat-treating at 400 to 800 ℃. So as to form a first sensitive layer 25And a second sensitive layer 26. The silica sol solution is coated on the entire surface of the substrate 21 including the first and second sensing layers 25 and 26 to a thickness of 10 to 100 μm, dried at 150 c, and treated at 600 c to form an insulating layer 27. Mixing the silica sol solution with palladium chloride (PdCl)2) The mixed solution of the ethanol solution is coated on the insulating layer 27 above the first sensitive layer 25 to a thickness of 10 to 50 μm, and dried and heat-treated to form the first buffer layer 28. Further using a silica sol solution and an aqueous solution (H) of platinum (IV) hexachloride hydrate2PtCl6＋H2O) is coated onA second buffer layer 29 is formed by coating a second sensitive layer 26 spaced apart from the first buffer layer 28 by apredetermined distance on the insulating layer 27, and drying and heat-treating the coated layer to a thickness of 10 to 50 μm. An ethanol solution in which palladium chloride is dissolved is coated on the first buffer layer 28 to a thickness of 10 to 50 μm, and the first catalyst layer 30 is formed after drying and heat treatment. An aqueous solution of platinum (IV) hexachloride hydrate is coated on the second buffer layer 29 to a thickness of 10 to 50 μ, and the second catalytic layer 31 is formed after drying and heat treatment. Next, a wire bonding process is performed in order to form the external electrodes, and a packaging process is completed, thereby completing the fabrication of the hydrocarbon gas sensor.
Referring to fig. 8, the wiring method of the thus formed hydrocarbon gas sensor is as follows: a predetermined power is supplied to the sensor having the heater 22, the first sensitive layer 25 and the second sensitive layer 26, and the resistance R is set4And a variable resistor VR2In series with the second sensitive layer 26, the resistance R3And a variable resistor VR1In series with the first sensing layer 25 to form a gas detection circuit. In this gas detection circuit, when the heater 22 is heated to 300 c to 500 c, and detection is started, the first sensing layer 25 and the second sensing layer 26 generate different electric signals from each other in proportion to respective changes in electric resistance caused by respective catalytic actions of the first catalyst layer 30 and the second catalyst layer 31, the catalytic actions being different between the first catalyst layer 30 and the second catalyst layer 31. Table 1 shows the sensitivity of the first sensitive layer 25 and the second sensitive layer 26, and from table 1 it can be seen that the first sensitive layer 25, which is connected to the first catalyst layer 30 and the first buffer layer 28, is particularly sensitive to hydrocarbon gases and ethanol, but not to carbon monoxide, whereas the second sensitive layer 26, which is connected to the second catalytic layer 31 and the second buffer layer 29, is particularly sensitive to ethanol. The resistance change ranges of the first sensitive layer 25 and the second sensitive layer 26 before and after detection are proportional to the gas sensitivity.
[ Table 1]
Sensitivity: resistance in clean air/resistance in the gas to be detected. Concentration of the gas to be detected: 500 ppm.
| Propane | CO | Ethanol | |
| First sensitivity | 20～50 | 2～3 | 10～30 |
| Second sensitivity | 1～2 | 1～2 | 10～50 |
Utilizing these characteristics, there is provided a hydrocarbon detection device that can selectively detect an alcohol gas and a hydrocarbon gas, as shown in fig. 9, including: a first comparing portion 51 for comparing the voltage from the first sensing layer 25 with a preset reference voltage and generating a comparison signal, a second comparing portion 52 for comparing the voltage from the second sensing layer 26 with a preset reference voltage and generating a comparison signal, a determining portion 53 for determining the presence of hydrocarbon gas in response to the signals from the first and second comparing portions 51 and 52 and generating a determination signal, and an alarm generating portion 54 for generating an alarm based on the signal from the determining portion 53.
The operation of the above-described hydrocarbon detection device is explained below with reference to fig. 10.
The first comparing part 51 compares the voltage from the first sensing layer 25 with a preset first reference voltage after the sensing (S11), and the second comparing part 52 compares the voltage from the second sensing layer 26 with a preset second reference voltage after the sensing (S12). If the voltage from the first sensing layer 25 is greater than the first reference voltage after the detection and the voltage from the second sensing layer 26 is less than the second reference voltage after the detection, the determining part 53 determines that the gas present is a hydrocarbon gas (S14) and the alarm generating part 54 generates an alarm to the user (S15). If the voltages from the first and second sensitive layers 25 and 26 are greater than the first and second reference voltages, respectively, after the detection, the determination section 53 determines that the gas present is an alcohol gas (S13), and the alarm section 54 gives an alarm to the user.
Since the sensor of the present invention can accurately separate combustible gas from different ambient gases and can selectively detect it, the sensor can be used for various gas detection systems.
In an alarm application for detecting LNG and LPG leaks, the sensor of the present invention can prevent the disadvantages of a false alarm of a conventional semiconductor gas sensor and improve the sensitivity to a low concentration gas as compared with a pellitator type gas sensor. The sensor of the invention can be used not only in exhaust gas analyzers for cars, but also in combination with other types of semiconductor sensors to form an array, so that the signals from the sensor array are processed by means of software library technology using a microprocessor, whereby only hydrocarbon gases can be detected accurately and selectively in different gas mixtures.
It will be apparent to those skilled in the art that various changes and modifications can be made in the hydrocarbon gas sensor and the method of manufacturing the same of the present invention without departing from the spirit or scope of the invention. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Claims (9)
1. A hydrocarbon gas sensor comprising: a substrate; a heater under the substrate; a plurality of electrodes on an upper portion of the substrate; a sensitive layer formed on the electrode; an outer cover layer formed on the sensitive layer, characterized in that,
each electrode is provided with a corresponding sensitive layer which is only sensitive to hydrocarbon;
an insulating layer is arranged above each sensitive layer to cover the sensitive layers;
forming a catalyst layer on the insulating layer corresponding to each of the sensitive layers, the catalyst layers being spaced apart from each other;
the outer cover layer includes an insulating layer and each catalyst layer, and the outer cover layer reacts with a reducing gas.
2. The hydrocarbon gas sensor of claim 1,
the outer cover layer may further include a buffer layer disposed between the insulating layer and each of the catalyst layers, the buffer layers being spaced apart from each other corresponding to each of the sensitive layers.
3. The hydrocarbon gas sensor of claim 1,
the insulating layer is formed by silicon dioxide with the thickness of 10-100 mu m;
some of the catalyst layers are formed of palladium chloride having a thickness of 10 to 50 μm, and the remaining catalyst layers are formed of platinum (IV) hexachloride hydrate having a thickness of 10 to 50 μm.
4. The hydrocarbon gas sensor of claim 2,
the insulating layer is formed by silicon dioxide with the thickness of about 10-100 mu m;
some of the buffer layers are formed of a mixture of silicon dioxide and palladium chloride having a thickness of about 10 to 50 μm, and the rest of the buffer layers are formed of a mixture of silicon dioxide and palladium chloride having a thickness of 10 to 50 μm;
some of the catalyst layers are formed of palladium chloride having a thickness of 10 to 50 μm, and the remaining catalyst layers are formed of platinum (IV) hexachloride hydrate having a thickness of 10 to 50 μm.
5. A method of manufacturing a hydrocarbon gas sensor, comprising the steps of:
providing a substrate;
forming a heater on a lower portion of the substrate;
forming a plurality of electrodes on an upper portion of a substrate;
forming a sensitive layer which is only sensitive to hydrocarbon on each electrode;
forming an insulating layer over all of the sensitive layers;
forming a catalyst layer on the insulating layer corresponding to each sensitive layer, the catalyst layers being spaced apart from each other,
the insulating layer and each catalyst layer constitute an outer cover layer that reacts with one reducing gas.
6. The method of claim 5, further comprising the steps of:
a buffer layer is formed between the insulating layer and each catalyst layer, the buffer layers being spaced apart from each other with respect to each sensitive layer, the insulating layer, each catalyst layer and the respective buffer layer constituting an outer cover layer.
7. The method of claim 5, wherein,
the insulating layer is formed by coating a silica sol solution with a thickness of 10-100 mu m, drying at 180 ℃ and performing heat treatment at 600 ℃;
some of the catalyst layers are formed by coating an ethanol solution in which palladium nitride is dissolved in a thickness of 10 to 50 μ, and the remaining catalyst layers are formed by dissolving an aqueous solution (H) in which platinum (IV) hexachlorohydride hydrate is dissolved2PtCl6＋H2O) is coated to a thickness of 10 to 50 mu and then passed throughDried at 180 ℃ and heat treated at 600 ℃.
8. The method of claim 6, wherein,
the insulating layer is formed by coating a silica sol solution to a thickness of 10-100 μm;
some of the buffer layers are formed by applying a mixed solution of a silica sol solution and an ethanol solution in which palladium chloride is dissolved to a thickness of 10 to 50 μm, and the remaining buffer layers are formed by applying a mixed solution of a silica sol solution and an aqueous solution in which platinum (IV) hexachloride hydrate is dissolved to a thickness of 10 to 50 μm;
some of the catalyst layers are formed by applying an ethanol solution in which palladium chloride is dissolved to a thickness of 10 to 50 mu, and the remaining catalyst layers are formed by applying an aqueous solution in which platinum (IV) hexachloride hydrate is dissolved to a thickness of 10 to 50 mu, and then are dried at a temperature of 180 ℃ and heat-treated at a temperature of 600 ℃ respectively.
9. A method of detecting hydrocarbons using a hydrocarbon gas sensor, the hydrocarbon gas sensor comprising: a substrate; two electrodes on the substrate; a sensitive layer which is only sensitive to hydrocarbon is arranged on each electrode, so that a first sensitive layer and a second sensitive layer are formed; an insulating layer covers the two sensitive layers; forming a first catalyst layer and a second catalyst layer on the insulating layer corresponding to the first and second sensitive layers, the catalyst layers being spaced apart from each other, the insulating layer and the first catalyst layer forming a first outer capping layer, and the insulating layer and the second catalyst layer forming a second outer capping layer, the outer capping layers being reacted with a reducing gas;
the method comprises the following steps:
comparing the voltages from the first sensitive layer and the second sensitive layer during detection with a preset first reference voltage and a preset second reference voltage respectively;
if the voltage from the first sensing layer is greater than the first reference voltage, comparing the voltage from the second sensing layer with a predetermined second reference voltage, and if the voltage from the second sensing layer is less than the predetermined second reference voltage, determining that the detected gas is a hydrocarbon gas.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019960032834A KR0166931B1 (en) | 1996-08-07 | 1996-08-07 | Hydrocarbon gas sensor and its manufacturing method |
| KR32834/96 | 1996-08-07 | ||
| KR66229/1996 | 1996-12-16 | ||
| KR32834/1996 | 1996-12-16 | ||
| KR1019960066229A KR0179263B1 (en) | 1996-12-16 | 1996-12-16 | Hydrocarbon gas sensor |
| KR66229/96 | 1996-12-16 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1178903A CN1178903A (en) | 1998-04-15 |
| CN1077687C true CN1077687C (en) | 2002-01-09 |
Family
ID=26632078
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN97119278.2A Expired - Fee Related CN1077687C (en) | 1996-08-07 | 1997-08-07 | Hydrocarbon gas sensor and its producing method |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH1082755A (en) |
| CN (1) | CN1077687C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20040043132A (en) * | 2001-11-14 | 2004-05-22 | 마츠시타 덴끼 산교 가부시키가이샤 | Gas sensor, and production method for gas sensor |
| JP2010185774A (en) * | 2009-02-12 | 2010-08-26 | Fuji Electric Systems Co Ltd | Membrane gas sensor |
| EP2278309B1 (en) * | 2009-07-21 | 2019-05-15 | ams international AG | A Sensor |
| EP3343212B1 (en) * | 2015-08-28 | 2019-11-06 | Panasonic Intellectual Property Management Co., Ltd. | Gas sensor and fuel cell vehicle |
| CN108061741B (en) * | 2017-11-14 | 2021-03-19 | 苏州慧闻纳米科技有限公司 | Multi-channel array sensor |
| KR102641207B1 (en) * | 2019-03-26 | 2024-02-28 | 엘지전자 주식회사 | A sensor module |
| CN111272828B (en) * | 2020-03-26 | 2022-04-12 | 微纳感知(合肥)技术有限公司 | MEMS gas sensor, array thereof and preparation method thereof |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5710446A (en) * | 1980-06-20 | 1982-01-20 | Nec Corp | Gas detecting element |
| JPS5766347A (en) * | 1980-10-09 | 1982-04-22 | Hitachi Ltd | Detector for mixture gas |
| JPS6029651A (en) * | 1983-07-27 | 1985-02-15 | Hitachi Ltd | Gas sensor for detecting many kinds of gases |
| JPH0382945A (en) * | 1989-08-25 | 1991-04-08 | Fuji Electric Co Ltd | Semiconductor gas sensor |
| JP2570440B2 (en) * | 1989-11-20 | 1997-01-08 | 富士電機株式会社 | Gas sensor |
| JPH03248054A (en) * | 1990-02-27 | 1991-11-06 | Fuji Electric Co Ltd | Gas sensor |
| JP2876793B2 (en) * | 1991-02-04 | 1999-03-31 | トヨタ自動車株式会社 | Semiconductor type hydrocarbon sensor |
-
1997
- 1997-08-07 CN CN97119278.2A patent/CN1077687C/en not_active Expired - Fee Related
- 1997-08-07 JP JP9212971A patent/JPH1082755A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN1178903A (en) | 1998-04-15 |
| JPH1082755A (en) | 1998-03-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4629665B2 (en) | Method and apparatus for sensing hydrogen gas | |
| CN101939639B (en) | Gas sensor with improved selectivity | |
| US5635628A (en) | Method for detecting methane in a gas mixture | |
| CN1077687C (en) | Hydrocarbon gas sensor and its producing method | |
| JPH09503587A (en) | Sensor for detecting nitrogen oxides | |
| JP2007121173A (en) | Gas sensor element and its manufacturing method | |
| JPH08261970A (en) | Device and method for sensing gas | |
| RU2532428C1 (en) | Manufacturing method of gas sensor with nanostructure, and gas sensor on its basis | |
| JPH10502428A (en) | Automotive catalyst performance monitoring system | |
| KR100252935B1 (en) | Apparatus for alarming and measuring gas-leakage | |
| KR0179263B1 (en) | Hydrocarbon gas sensor | |
| KR0166931B1 (en) | Hydrocarbon gas sensor and its manufacturing method | |
| JPH07260728A (en) | Carbon monoxide gas sensor | |
| WO2016148500A1 (en) | Hydrogen detection sensor for detecting hydrogen of wide concentration range | |
| US6638406B2 (en) | Hydrocarbon sensor and method for producing the same | |
| KR101133820B1 (en) | Electrochemical sensor | |
| JP2946090B2 (en) | Manufacturing method of ammonia gas sensor | |
| KR100771526B1 (en) | Gas sensor and manufactutring method thereof | |
| JP3170396B2 (en) | Semiconductor type ammonia gas sensor and method of manufacturing the same | |
| JP4507438B2 (en) | Gas detection method using a gas sensor | |
| KR100246719B1 (en) | Nox gas sensor using wo3 sensing layer and its manufacturing method | |
| US20030217921A1 (en) | Gas sensor | |
| KR100780076B1 (en) | Method for forming sensitizer for semiconductor type gas sensor and semiconductor type gas sensor array | |
| JP2021032649A (en) | Oxygen sensor | |
| JP2004294127A (en) | Humidity sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |