CN112326751A - Nitrogen oxide sensor, preparation method thereof and nitrogen oxide detection device - Google Patents
Nitrogen oxide sensor, preparation method thereof and nitrogen oxide detection device Download PDFInfo
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Abstract
The invention relates to the technical field of gas detection, and firstly provides a nitrogen oxide sensor which comprises a substrate and a heating layer arranged on the substrate, and further comprises: an insulating layer disposed on the heating layer, and; a first sensing unit disposed on the insulating layer, and; the second sensitive unit is arranged on the insulating layer, the surface of the second sensitive unit is covered with a passivation layer, and the passivation layer is used for isolating the second sensitive unit from the external environment; and the external circuit is connected with the first sensitive unit and the second sensitive unit together to form a bridge circuit. The invention further provides a method for preparing the sensor and a nitrogen oxide detection device comprising the sensor. The nitrogen oxide sensor can compensate the fluctuation interference of electrical signals caused by temperature fluctuation, thereby improving the detection precision in actual detection.
Description
Technical Field
The invention relates to the technical field of gas detection, in particular to a nitrogen oxide sensor, a preparation method thereof and a nitrogen oxide detection device.
Background
At present, nitrogen oxides are a key factor causing material corrosion, and the detection of nitrogen oxide gas is particularly important, since the nitrogen oxides mainly come from pollutants discharged from various enterprises, incineration treatment of household garbage, and the like.
Currently, the majority of commercially available devices for measuring low levels of nitrogen oxides are chemiluminescent analyzers. For example, patent specification CN103575695B discloses a device for detecting the content of nitrogen oxides in gas, which comprises: the device comprises a processor, a program-controlled current source, a laser, a gas absorption cell, a detector and a signal conditioner, wherein the gas absorption cell is provided with a broken line type gas chamber, the broken line type gas chamber is provided with a gas inlet hole and a gas outlet hole, gas to be detected enters the broken line type gas chamber from the gas inlet hole, flows along the broken line type gas chamber and flows out of the broken line type gas chamber from the gas outlet hole; the broken line type air chamber is also provided with a light incident hole and a light emergent hole; and the incident laser enters the fold line type air chamber from the light incident hole, is reflected along the fold line type air chamber and is emitted from the light emergent hole. According to the scheme, the concentration of the nitrogen oxide in the gas to be detected is obtained through the intensity of the second harmonic of the finally emitted laser, a traditional sensor is not needed, but the online analyzer is large in size and mass, very expensive in price and complex in maintenance.
One possible alternative at present is to use a gas-sensitive resistor to measure low-concentration nitrogen oxides. For example, patent specification CN102608183B discloses a nitroxide sensor, which comprises a zirconia substrate, two sensing electrodes and a reference electrode; the zirconia matrix is made of yttria-stabilized zirconia, two sensing electrodes are arranged on the zirconia matrix and used for being in contact with detected gas, one sensing electrode is sensitive to NO gas, the other sensing electrode is sensitive to NO2 gas, a reference electrode is arranged on the other side of the zirconia matrix and used for being in contact with air, and the two sensing electrodes are respectively and electrically connected with the reference electrode. However, when the working environment temperature fluctuates, the fluctuation interference of the electrical signal can be generated, and the measurement result is influenced, but the scheme does not consider that the base body is influenced by the environment temperature, and the fluctuation change of the electrical signal can be generated under the condition of the temperature fluctuation, so that the measurement result is not accurate enough.
Content of application
A first object of the present invention is to provide an nox sensor, which improves the accuracy of the measurement result by providing a passivation layer on one of two sensitive units and by forming a bridge circuit to compensate for the interference of the fluctuation of the electrical signal caused by the temperature fluctuation.
A second object of the present invention is to provide a method for manufacturing a nox sensor, which can rapidly manufacture the above-mentioned nox sensor.
A third object of the present invention is to provide a nitrogen oxide detection apparatus, which can detect the concentration of nitrogen oxide in an environment more accurately by using the above-mentioned nitrogen oxide sensor, and has better portability.
The invention is realized by the following technical scheme:
first, the present invention provides an nox sensor including a substrate and a heating layer provided on the substrate, and further including:
an insulating layer disposed on the heating layer;
a first sensing unit arranged on the insulating layer, and;
the surface of the second sensitive unit is covered with a passivation layer which is used for isolating the second sensitive unit from the external environment;
and the external circuit is connected with the first sensitive unit and the second sensitive unit together to form a bridge circuit.
According to the invention, the first sensitive unit and the second sensitive unit are arranged on the insulating layer, and it should be noted that the first sensitive unit and the second sensitive unit are identical in structure and function. The surface of the second sensitive unit is covered with a passivation layer which isolates the second sensitive unit from the external environment, and the first sensitive unit, the second sensitive unit and an external circuit are electrically connected, so that a finished bridge circuit is formed. When the temperature of the substrate fluctuates due to the influence of the temperature of the external environment, the resistance value of the electrical element arranged on the substrate changes, and then the change appears as fluctuation of current or voltage signals, and the change is not caused by the gas sensitivity of the material of the electrical element. Therefore, by adopting the above arrangement, after the first sensing unit, the second sensing unit and the external circuit are connected into the bridge circuit, even if the substrate temperature fluctuates, the resistance value changes of the first sensing unit and the second sensing unit are equal, so that the mutual cancellation effect can be generated, thereby reducing the influence of fluctuation interference of the electrical signals caused by temperature fluctuation and improving the measurement precision.
Optionally, the heating layer is a nickel-chromium alloy film, and a power supply electrode is arranged on the heating layer.
Optionally, the first sensing unit is a tin dioxide film, a zirconium dioxide film or a zirconium dioxide doped scandium film with a micro-nano porous structure.
Optionally, the passivation layer is made of silicon dioxide, silicon nitride or aluminum oxide.
Optionally, the external circuit includes a first resistor, an adjustable resistor, and a second resistor connected in parallel with the first sensing unit and the second sensing unit.
Optionally, the insulating layer is made of silicon dioxide.
Secondly, the invention provides a method for preparing the nitrogen oxide sensor, which comprises the following steps:
s1, manufacturing the heating layer on the substrate;
s2, manufacturing the insulating layer on the heating layer by adopting a PECVD method;
s3, respectively manufacturing the first sensitive unit and the second sensitive unit on the insulating layer by adopting a vacuum spraying method;
and S4, manufacturing a passivation layer on the surface of the second sensitive unit by adopting a PECVD method.
Optionally, the method for manufacturing the heating layer in step S1 adopts a vacuum cold spraying method.
Finally, the present invention provides a nitrogen oxide detection apparatus including the nitrogen oxide sensor described above, and further including:
an amplifier electrically connected to a bridge circuit formed by the NOx sensor;
an analog-to-digital converter electrically connected to the amplifier;
and the power supply control device is used for supplying electric energy to the nitrogen oxide sensor, the amplifier and the analog-to-digital converter.
Optionally, the detection device further includes a digital display device electrically connected to the analog-to-digital converter.
The technical scheme of the embodiment of the invention at least has the following advantages and beneficial effects:
1. the gas sensor is reasonable in design and simple in structure, the heating layer provides the first sensitive unit and the second sensitive unit with the working temperature of 100-250 ℃, the first sensitive unit is easy to adsorb gas molecules under the temperature condition, and the gas molecules are convenient to diffuse to the surface and the grain boundary of the first sensitive unit, so that the gas sensitivity of the first sensitive unit is higher. Meanwhile, symmetrical positive and negative voltages are provided for the first sensitive unit and the second sensitive unit, so that the potential between the first sensitive unit and the second sensitive unit is zero, and the interference of electric signal fluctuation caused by temperature fluctuation is overcome through a formed bridge circuit by using a bridge type differential amplification method, so that the measurement accuracy is improved.
2. The minimum measurement accuracy of the invention is reduced from the ppm level to the 10ppb level, considering that the typical nitrogen oxide concentration in urban atmosphere is about 10-50ppb (12-60 mug/m)3) Therefore, the method can be applied to monitoring the concentration of the nitrogen oxide in the atmospheric environment.
3. The invention adopts the vacuum cold spraying and mask technology to manufacture the nichrome film as the heating layer, can accurately control the size of the nichrome film and is convenient for batch manufacturing; meanwhile, the first sensitive unit and the second sensitive unit with the micro-nano porous structure are manufactured by a vacuum spraying method to serve as the sensitive units of the nitrogen oxide gas, the sizes of the first sensitive unit and the second sensitive unit can be accurately controlled, and the method has the characteristics of high sensitivity, quick response, high material repeatability and small resistance value dispersity and is convenient for batch manufacturing.
4. The nitrogen oxide detection device has the advantages of simple structure, good detection effect on nitrogen oxide, small volume, convenient maintenance and low maintenance cost.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a sectional view of a nitrogen oxide sensor provided in embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a nox sensor provided in embodiment 1 of the present invention;
FIG. 3 is an electrical block diagram of an apparatus for detecting NOx provided in embodiment 5 of the present invention;
fig. 4 is a circuit diagram of an nox detection apparatus according to embodiment 5 of the present invention.
Icon: the sensor comprises a nitrogen oxide sensor, 101-a substrate, 102-a heating layer, 103-a power supply electrode, 104-an insulating layer, 105-a first sensitive unit, 106-a second sensitive unit, 107-a passivation layer, 108-a first resistor, 109-an adjustable resistor, 1010-a second resistor, 1011-a pin, a 2-amplifier, a 3-analog-digital converter, a 4-power supply control device and a 5-digital display device.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually placed when the product of this application is used, the description is merely for convenience and simplicity of description, and it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1 and 2, the present embodiment provides an nox sensor 1 including a substrate 101 and a heating layer 102 provided on the substrate 101. The substrate 101 may be, but is not limited to, aluminum oxide, the heating layer 102 may be a nickel-chromium alloy thin film, and a power supply electrode 103 is disposed on the heating layer 102, so as to connect the heating layer 102 with an external power supply, and supply power to the external power supply to realize heating.
In this embodiment, the nichrome film has the advantages of strong oxidation resistance, good heating performance and the like, and is designed into a reciprocating and zigzag 'snake' -shaped structure, the thickness of the nichrome film is 300nm, the width of the nichrome film is 0.1-0.5mm, and the reciprocating interval is 0.1-0.5mm, so that the heating area can be effectively increased, and sufficient and stable working temperature is provided for the nitrogen oxide sensor 1.
Further, the nox sensor 1 includes:
the insulating layer 104 is arranged on the heating layer 102, and the material of the insulating layer 104 can be silicon dioxide, so that the insulating layer has excellent insulating property, and the first sensitive unit 105 and the second sensitive unit 106 which are arranged on the insulating layer are effectively prevented from being in electrical contact with the heating layer 102, thereby influencing actual measurement. In this embodiment, the thickness of the insulating layer 104 is 300 nm.
The first sensing unit 105 and the second sensing unit 106 are disposed on the insulating layer 104 at intervals. The surface of the second sensing unit 106 is covered with a passivation layer 107, and the passivation layer 107 is used for isolating the second sensing unit 106 from the external environment, so as to prevent the second sensing unit 106 from contacting the gas to be measured in the environment. The first sensing unit 105 and the second sensing unit 106 are made of an oxide gas-sensitive resistor material, which can be, but not limited to, a tin dioxide thin film, a zirconium dioxide thin film, or a zirconium dioxide-doped scandium thin film, and have a thickness of 200-. And the material of the passivation layer 107 can be, but is not limited to, silicon dioxide, silicon nitride, aluminum oxide, or the like.
Meanwhile, the first sensing unit 105 is a tin dioxide film, a zirconium dioxide film or a zirconium dioxide doped scandium film with a micro-nano porous structure. The structure can be compact in a high-temperature working environment for a long time, and the problems that the gas is difficult to diffuse in the first sensitive unit 105, the gas sensitivity of the first sensitive unit 105 is reduced and the like are avoided.
In addition, the nox sensor 1 comprises an external circuit, which is connected to the first sensor unit 105 and the second sensor unit 106 together to form a bridge circuit. Wherein the external circuit comprises a first resistor 108, an adjustable resistor 109 and a second resistor 1010 connected in parallel with the first sensing cell 105 and the second sensing cell 106. The first resistor 108, the adjustable resistor 109 and the second resistor 1010 provide a bypass reference voltage, and form a bridge circuit together with the first sensing unit 105 and the second sensing unit 106, and the adjustable resistor 109 is used for calibrating and zeroing the differential voltage.
In this way, in the present embodiment, by disposing the first sensing unit 105 and the second sensing unit 106 on the insulating layer 104, it should be noted that the first sensing unit 105 and the second sensing unit 106 are identical in structure and function. The surface of the second sensing unit 106 is covered with a passivation layer 107 for isolating the second sensing unit 106 from the external environment, and the first sensing unit 105, the second sensing unit 106 and the external circuit are electrically connected to form a completed bridge circuit. When the temperature of the substrate 101 fluctuates due to the temperature of the external environment, the resistance of the electrical element disposed on the substrate 101 changes, and thus the change is represented as a fluctuation of the current or voltage signal, and the change is not caused by the gas sensitivity of the material of the electrical element. Therefore, by adopting the above arrangement, after the first sensing unit 105, the second sensing unit 106 and the external circuit are connected to form a bridge circuit, even if the temperature of the substrate 101 fluctuates, the resistance changes of the first sensing unit 105 and the second sensing unit 106 are equal, so that the mutual cancellation effect can be generated, thereby reducing the influence of fluctuation interference of the electrical signal caused by the temperature fluctuation and improving the measurement accuracy.
In an actual test, the heating layer 102 can be used to provide an operating temperature of 100-. Meanwhile, symmetrical positive and negative voltages are provided for the first sensitive unit 105 and the second sensitive unit 106, so that the potential between the first sensitive unit and the second sensitive unit is zero, and the fluctuation interference of electrical signals caused by temperature fluctuation is overcome by a formed bridge circuit and a bridge type differential amplification method, so that the measurement accuracy is improved.
In addition, the minimum measurement accuracy of the NOx sensor 1 is reduced from the ppm level to the 10ppb level, considering that the typical NOx concentration in urban atmosphere is about 10-50ppb (12-60 μ g/m)3) Therefore, the nitrogen oxide sensor 1 can be applied to monitoring the nitrogen oxide concentration in the atmospheric environment.
Example 2
The present embodiment provides a method for manufacturing the nox sensor 1 according to embodiment 1, including the following steps:
s1, manufacturing a heating layer 102 on a substrate 101 by adopting a vacuum cold spraying method and a mask technology, wherein the heating layer 102 is manufactured by adopting a laser etching technology to manufacture a mask plate, the distance between the mask and a sample is 0mm, the vacuum spraying distance is 20mm, the gun moving speed is 50mm/s, the vacuum degree is 10Pa, the pressure of accelerating gas and helium is 0.6MPa, the flow is 9L/min, the thickness of the heating layer is 300nm, the width of the heating layer is 0.1mm, the reciprocating interval is 0.1mm, and the total size of the heating layer is 0.6mm3The reciprocating zigzag nickel-chromium alloy film is in a snake shape, and is manufactured at two end points of the nickel-chromium alloy filmA metal power supply electrode 103 for supplying electric energy to the nichrome film to heat it;
s2, manufacturing a silicon dioxide insulating layer 104 with the thickness of 300nm on the heating layer 102 by adopting a PECVD method;
s3, respectively manufacturing a first sensitive unit 105 and a second sensitive unit 106 on the insulating layer 104 by adopting a vacuum spraying method; specifically, spraying is carried out according to the parameters of a vacuum spraying distance of 15mm, a gun moving speed of 30mm/s, a vacuum degree of 10Pa, an accelerating gas helium pressure of 0.5MPa and a flow rate of 12L/min, wherein a base material is tin dioxide doped with 10% graphene micro-nano powder, two independent tin dioxide thin films with the thickness of 200nm are prepared on the top of a silicon dioxide insulating layer 104, graphene in the thin films is decomposed by introducing oxygen at the temperature of 300 ℃ for annealing for 1 hour, the tin dioxide thin films with the micro-nano porous structure are obtained, and two independent tin dioxide thin film table tops with the thickness of 200nm are prepared on the top of the silicon dioxide insulating layer 104 and are used as a first sensitive unit 105 and a second sensitive unit 106;
and S4, manufacturing a passivation layer 107 on the surface of the second sensitive unit 106 by adopting a PECVD method.
In addition, metal electrodes are required to be manufactured at the positive and negative power supply ends and the signal ends of the first sensing unit 105 and the second sensing unit 106, so that the metal electrodes can be conveniently connected with an external circuit to form a bridge circuit. Meanwhile, the power supply electrode 103 on the heating layer 102 and the metal electrodes of the first sensing unit 105 and the second sensing unit 106 are welded to the pins 1011 using a silicon-aluminum alloy wire.
The nichrome film manufactured by adopting the vacuum cold spraying and mask technology is used as the heating layer 102, so that the size of the nichrome film can be accurately controlled, and the batch manufacturing is facilitated; meanwhile, the first sensitive unit 105 and the second sensitive unit 106 with the micro-nano porous structure are manufactured by a vacuum spraying method and used as sensitive units for detecting nitrogen oxide gas, the sizes of the first sensitive unit 105 and the second sensitive unit 106 can be accurately controlled, and the method has the characteristics of high sensitivity, quick response, high material repeatability and small resistance value dispersity and is convenient for batch manufacturing.
Example 3
The present embodiment provides a method for manufacturing the nox sensor 1 according to embodiment 1, including the following steps:
s1, manufacturing a heating layer 102 on a substrate 101 by adopting a vacuum cold spraying method and a mask technology, wherein the heating layer 102 is manufactured by adopting a laser etching technology to manufacture a mask plate, the distance between the mask and a sample is 0mm, the vacuum spraying distance is 20mm, the gun moving speed is 50mm/s, the vacuum degree is 10Pa, the pressure of accelerating gas and helium is 0.6MPa, the flow is 9L/min, the thickness of the heating layer is 300nm, the width of the heating layer is 0.2mm, the reciprocating interval is 0.2mm, and the total size of the heating layer is 1mm3The reciprocating zigzag nickel-chromium alloy film is in a snake shape, and metal power supply electrodes 103 are manufactured at two end points of the nickel-chromium alloy film so as to provide electric energy for the nickel-chromium alloy film to heat the nickel-chromium alloy film;
s2, manufacturing a silicon dioxide insulating layer 104 with the thickness of 300nm on the heating layer 102 by adopting a PECVD method;
s3, respectively manufacturing a first sensitive unit 105 and a second sensitive unit 106 on the insulating layer 104 by adopting a vacuum spraying method; specifically, spraying is carried out according to the parameters of a vacuum spraying distance of 15mm, a gun moving speed of 30mm/s, a vacuum degree of 20Pa, an accelerating gas helium pressure of 0.8MPa and a flow rate of 15L/min, wherein a base material is 15% graphene micro-nano powder doped zirconium dioxide, two independent zirconium dioxide thin films with the thickness of 1000nm are prepared on the top of a silicon dioxide insulating layer 104, graphene in the thin films is decomposed by introducing oxygen at 300 ℃ and annealing for 1 hour, the zirconium dioxide thin films with a micro-nano porous structure are obtained, and two independent zirconium dioxide thin film table tops with the thickness of 200nm are prepared on the top of the silicon dioxide insulating layer 104 and are used as a first sensing unit 105 and a second sensing unit 106;
and S4, manufacturing a passivation layer 107 on the surface of the second sensitive unit 106 by adopting a PECVD method.
In addition, metal electrodes are required to be manufactured at the positive and negative power supply ends and the signal ends of the first sensing unit 105 and the second sensing unit 106, so that the metal electrodes can be conveniently connected with an external circuit to form a bridge circuit. Meanwhile, the power supply electrode 103 on the heating layer 102 and the metal electrodes of the first sensing unit 105 and the second sensing unit 106 are welded to the pins 1011 using a silicon-aluminum alloy wire.
Example 4
The present embodiment provides a method for manufacturing the nox sensor 1 according to embodiment 1, including the following steps:
s1, manufacturing a heating layer 102 on a substrate 101 by adopting a vacuum cold spraying method and a mask technology, wherein the heating layer 102 is manufactured by adopting a laser etching technology to manufacture a mask plate, the distance between the mask and a sample is 0mm, the vacuum spraying distance is 20mm, the gun moving speed is 50mm/s, the vacuum degree is 10Pa, the pressure of accelerating gas and helium is 0.6MPa, the flow is 9L/min, the thickness of the heating layer is 300nm, the width of the heating layer is 0.5mm, the reciprocating interval is 0.5mm, and the total size of the heating layer is 3mm3The reciprocating zigzag nickel-chromium alloy film is in a snake shape, and metal power supply electrodes 103 are manufactured at two end points of the nickel-chromium alloy film so as to provide electric energy for the nickel-chromium alloy film to heat the nickel-chromium alloy film;
s2, manufacturing a silicon dioxide insulating layer 104 with the thickness of 300nm on the heating layer 102 by adopting a PECVD method;
s3, respectively manufacturing a first sensitive unit 105 and a second sensitive unit 106 on the insulating layer 104 by adopting a vacuum spraying method; specifically, spraying is carried out according to the parameters of a vacuum spraying distance of 10mm, a gun moving speed of 30mm/s, a vacuum degree of 10Pa, an accelerating gas helium pressure of 0.8MPa and a flow rate of 12L/min, wherein a base material is 20% graphene micro-nano powder doped zirconium dioxide, two independent zirconium dioxide doped scandium thin films with the thickness of 2000nm are prepared on the top of a silicon dioxide insulating layer 104, graphene in the thin films is decomposed by introducing oxygen and annealing for 1 hour at 300 ℃, the zirconium dioxide doped scandium thin films with a micro-nano porous structure are obtained, and two independent zirconium dioxide doped scandium thin film table tops with the thickness of 200nm are prepared on the top of the silicon dioxide insulating layer 104 and are used as a first sensing unit 105 and a second sensing unit 106;
and S4, manufacturing a passivation layer 107 on the surface of the second sensitive unit 106 by adopting a PECVD method.
In addition, metal electrodes are required to be manufactured at the positive and negative power supply ends and the signal ends of the first sensing unit 105 and the second sensing unit 106, so that the metal electrodes can be conveniently connected with an external circuit to form a bridge circuit. Meanwhile, the power supply electrode 103 on the heating layer 102 and the metal electrodes of the first sensing unit 105 and the second sensing unit 106 are welded to the pins 1011 using a silicon-aluminum alloy wire.
Example 5
Finally, referring to fig. 3 and 4, the present embodiment provides a nitrogen oxide detection apparatus including the nitrogen oxide sensor 1 as described in embodiment 1 above, and further including:
an amplifier 2 for the method analog signal, which is electrically connected to the bridge circuit formed by the nox sensor 1, and;
the analog-to-digital converter 3 is electrically connected with the amplifier 2 and is used for converting the analog signal into a digital signal;
a power supply control device 4 for supplying electrical energy to the nox sensor 1, the amplifier 2 and the analog-digital converter 3, wherein the power supply control device 4 is also capable of controlling the heating power of the heating layer 102.
In addition, the detection device also comprises a digital display device 5 electrically connected with the analog-to-digital converter 3 so as to display the detection result in real time.
During actual detection, the nitrogen oxide sensor 1 adsorbs nitrogen oxide molecules in the environment at high temperature, and after the nitrogen oxide molecules acquire electrons on the surface layer of the material of the nitrogen oxide sensor 1 and inject holes, the resistance of the nitrogen oxide sensor 1 is reduced, so that a differential electrical signal is provided, the gas concentration is converted into a voltage analog signal, and the detection of the nitrogen oxide is realized. The amplifier 2 and the analog-to-digital converter 3 are used for amplifying the analog signal and converting the analog signal into a digital signal, and the digital display device 5 is used for displaying the measurement result.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a nitrogen oxide sensor, includes the substrate and locates zone of heating on the substrate which characterized in that still includes:
an insulating layer disposed on the heating layer;
a first sensing unit arranged on the insulating layer, and;
the surface of the second sensitive unit is covered with a passivation layer which is used for isolating the second sensitive unit from the external environment;
and the external circuit is connected with the first sensitive unit and the second sensitive unit together to form a bridge circuit.
2. The nox sensor of claim 1, wherein: the heating layer is a nickel-chromium alloy film, and a power supply electrode is arranged on the heating layer.
3. The nox sensor of claim 1, wherein: the first sensitive unit is a tin dioxide film, a zirconium dioxide film or a zirconium dioxide doped scandium film with a micro-nano porous structure.
4. The nox sensor of claim 1, wherein: the passivation layer is made of silicon dioxide, silicon nitride or aluminum oxide.
5. The nox sensor of claim 1, wherein: the external circuit comprises a first resistor, an adjustable resistor and a second resistor which are connected with the first sensing unit and the second sensing unit in parallel.
6. The nox sensor of claim 1, wherein: the insulating layer is made of silicon dioxide.
7. A method of manufacturing a nox sensor according to any one of claims 1 to 6, comprising the steps of:
s1, manufacturing the heating layer on the substrate;
s2, manufacturing the insulating layer on the heating layer by adopting a PECVD method;
s3, respectively manufacturing the first sensitive unit and the second sensitive unit on the insulating layer by adopting a vacuum spraying method;
and S4, manufacturing a passivation layer on the surface of the second sensitive unit by adopting a PECVD method.
8. The method for producing a nitrogen oxide sensor according to claim 7, wherein: the method for manufacturing the heating layer in the step S1 adopts a vacuum cold spraying method.
9. A nitrogen oxide detection apparatus including the nitrogen oxide sensor according to any one of claims 1 to 6, characterized by further comprising:
an amplifier electrically connected to a bridge circuit formed by the NOx sensor;
an analog-to-digital converter electrically connected to the amplifier;
and the power supply control device is used for supplying electric energy to the nitrogen oxide sensor, the amplifier and the analog-to-digital converter.
10. The nitrogen oxide detection device according to claim 9, characterized in that: the digital display device is electrically connected with the analog-to-digital converter.
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| CN110426422A (en) * | 2019-09-12 | 2019-11-08 | 中国工程物理研究院总体工程研究所 | Membrane bridge pressure type nitrogen atmosphere sensor |
| CN111024777A (en) * | 2019-12-25 | 2020-04-17 | 广州钰芯传感科技有限公司 | Sensor for modifying tin oxide, preparation method thereof and application of sensor in gas-sensitive detection of nitric oxide |
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2020
- 2020-11-09 CN CN202011242164.7A patent/CN112326751A/en active Pending
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| WO2009051180A1 (en) * | 2007-10-18 | 2009-04-23 | Alps Electric Co., Ltd. | Offset adjusting circuit for bridge circuit output voltage |
| CN201159726Y (en) * | 2007-11-19 | 2008-12-03 | 比亚迪股份有限公司 | Titanium oxide type oxygen sensor |
| CN102608183A (en) * | 2012-03-13 | 2012-07-25 | 华中科技大学 | Nitrogen-oxygen sensor |
| CN206583845U (en) * | 2017-03-24 | 2017-10-24 | 湖北大学 | Adaptive density of hydrogen detection circuit based on hydrogen gas sensor |
| CN110426422A (en) * | 2019-09-12 | 2019-11-08 | 中国工程物理研究院总体工程研究所 | Membrane bridge pressure type nitrogen atmosphere sensor |
| CN111024777A (en) * | 2019-12-25 | 2020-04-17 | 广州钰芯传感科技有限公司 | Sensor for modifying tin oxide, preparation method thereof and application of sensor in gas-sensitive detection of nitric oxide |
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