CN107677707B - LTCC-based substrate integrated waveguide type wireless passive gas sensor and preparation method thereof - Google Patents
LTCC-based substrate integrated waveguide type wireless passive gas sensor and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of gas sensing, and particularly relates to a LTCC-based substrate integrated waveguide type wireless passive gas sensor and a preparation method thereof. The problem of current gas sensor wired connection, it is inconvenient to install, life cycle short scheduling is solved, including the upper surface metal level, lower surface metal level and the LTCC aluminium oxide potsherd of setting in the middle of, the upper surface metal level, the substrate is constituteed to lower surface metal level and LTCC aluminium oxide potsherd, the substrate week side is equipped with the lateral wall metal cylinder through-hole of the integrated waveguide of round substrate, constitute the structure based on the integrated waveguide of substrate with this, the lateral wall metal cylinder through-hole intussuseption of the integrated waveguide of substrate is filled with silver thick liquids, the substrate middle part is equipped with gaseous sensitive structure, upper surface metal layer surface is. The invention fully utilizes the advantages of high quality factor, low loss and the like of the substrate integrated waveguide resonator, and can effectively increase the distance of wireless test.
Description
Technical Field
The invention belongs to the technical field of gas sensing, and particularly relates to a LTCC-based substrate integrated waveguide type wireless passive gas sensor and a preparation method thereof.
Background
Under the drive of the rapid development of scientific technology and petrochemical industry, flammable, explosive and toxic gases are widely used. When the gas leaks in the processes of transportation, storage and use, the gas can cause personnel poisoning, cause atmospheric pollution, fire and even explosion, and cause people to be poisonedThe safety of lives and assets of people is threatened greatly. For example: during the mining process of some mine holes and mines, a large amount of H is generated2S, CO, which is a dangerous hazard to personnel. When some chemical plants transport and store inflammable and volatile poisonous and harmful chemical raw materials, leakage accidents often occur, and if the leakage accidents cannot be found in time, great danger is caused, and the health of people is directly influenced or the environment is polluted. In addition, at present, haze in many cities in China is very serious, the haze causes great damage to respiratory tracts of human bodies, and death can even be caused if the haze is inhaled for a long time, so that the problem of air pollution becomes a problem which is highly concerned and urgently needed to be solved by people. Therefore, the detection of these harmful gases is very significant, and the research of corresponding gas-sensitive detection sensors is becoming more and more significant.
The existing gas sensors generally adopt a wired connection mode, and have high detection sensitivity and short detection response time. However, the installation of the wired sensor causes great inconvenience, and the service life of the sensor is seriously affected by great power consumption. The problems of power consumption and installation can be well solved due to the appearance of the wireless passive gas sensor, so that the design and preparation of the wireless passive gas sensor have great research significance. In addition, the integrated structure based on the substrate has the advantages of high quality factor and low loss, and can realize wireless test at a longer distance.
Disclosure of Invention
The invention provides a substrate integrated waveguide wireless passive gas sensor based on LTCC and a preparation method thereof, aiming at solving the problems of the existing gas sensor such as wired connection, inconvenient installation, short service cycle and the like.
The invention adopts the following technical scheme: the utility model provides a wireless passive gas sensor of substrate integrated waveguide formula based on LTCC, including the upper surface metal level, lower surface metal level and the LTCC aluminium oxide potsherd of setting in the middle of, the upper surface metal level, the substrate is constituteed to lower surface metal level and LTCC aluminium oxide potsherd, substrate week side is equipped with the lateral wall metal cylinder through-hole of the integrated waveguide of round substrate, constitute the structure based on the integrated waveguide of substrate with this, the lateral wall metal cylinder through-hole intussuseption of the integrated waveguide of substrate is filled with silver thick liquids, the substrate middle part is equipped with gaseous sensitive structure, upper surface metal layer surface is equipped with.
Further, the gas sensitive structure comprises a cylindrical hole formed in the LTCC alumina ceramic chip, a layer of silver paste is coated on the inner surface of the cylindrical hole, and a graphene oxide coating is coated on the outer side of the silver paste.
Furthermore, the LTCC alumina ceramic sheet is provided with 6 layers.
A preparation method of a substrate integrated waveguide type wireless passive gas sensor based on LTCC comprises the following specific steps:
1) firstly, 6 pieces of LTCC green tapes are prepared, the numbers from the first layer to the sixth layer are 9-14, 9-11 three layers of LTCC green tapes are laminated for 20 minutes under the parameters of 70 ℃ and 21MPa, and then 25 cylinders are cut off at the middle position of the laminated 9-11 layers of green tapes.
2) And continuously laminating 9-11 layers of the cylindrical green porcelain tapes and 12-14 layers of the cylindrical green porcelain tapes, wherein the lamination is carried out for 20 minutes under the condition that the lamination parameters are 70 ℃ and 21 MPa.
3) Cutting off a series of small cylindrical through holes at the position of one circle on the peripheral side of the laminated 9-14 layers of green porcelain tapes, filling the cut small cylindrical through holes with silver paste, and brushing the inner walls of the 25 small cylindrical through holes cut off in the first step with the silver paste.
4) And (4) sintering the green porcelain tape printed with the silver paste in the third step in a high-temperature furnace at 850 ℃ to obtain 9-14 layers of cooked porcelain.
5) Printing silver paste on the upper surfaces of 9-14 layers of the porcelain by adopting a screen printing process, and sintering at 850 ℃ in a high-temperature furnace to obtain an upper metal surface of the substrate integrated waveguide and a slot antenna structure; and printing silver paste on the lower surfaces of the 9-14 layers of the porcelain, and sintering to obtain the lower metal surface of the substrate integrated waveguide.
6) Preparing graphene oxide, namely adding 100mL of concentrated sulfuric acid and 10mL of phosphoric acid into a three-necked bottle in sequence; placing the mixed acid in an ice-water bath, adding 0.8g of crystalline flake graphite and 5g of potassium permanganate, and stirring for 45 min; placing the mixture in a constant temperature water tank of 45-55 ℃ to be stirred for 35min, and then placing the mixture in a constant temperature water tank of 60 ℃ to react for 16h, wherein the mixture is dark green; dropwise adding 50mL of 5% hydrogen peroxide, and fully stirring until the mixture turns golden yellow; transferring the product to a beaker, standing at normal temperature, cooling, and washing with deionized water for multiple times until the product is neutral; and (3) drying the washed product in a drying oven at 60 ℃, wherein the obtained product is graphene oxide.
7) And doping the graphene oxide prepared in the sixth step with zinc oxide in a mass ratio of 5%, uniformly grinding the graphene oxide and the zinc oxide by using an agate mortar, adding deionized water, and preparing into slurry serving as the gas-sensitive material.
8) And (4) uniformly spin-coating the gas-sensitive material prepared in the seventh step on the side walls and the lower surfaces of the 25 cylindrical holes cut out in the first step to prepare the final wireless passive gas sensor.
In the actual test process, the gas sensitive materials on the side walls and the lower surfaces of the 25 cylindrical holes in the middle of the sensor adsorb ethanol gas, the effective dielectric constant of the cylindrical hole parts is changed, the resonant frequency of the sensor is changed according to the medium perturbation theory of the substrate integrated waveguide, and the gas with different concentrations causes the resonant frequency of the sensor to generate different-degree shifts, so that the detection of the gas concentration is realized.
Compared with the prior art, the invention has the following beneficial effects:
1) the invention provides a method for integrating a slot antenna on a substrate integrated waveguide structure to realize wireless and passive electromagnetic wave coupling, and a cylindrical hole for bearing a gas-sensitive material is prepared at the center of the structure under the condition of not changing the electromagnetic field distribution of the substrate integrated waveguide.
2) According to the gas sensor prepared by doping the prepared graphene oxide and the zinc oxide, the gas-sensitive material is prepared, so that the adsorption area of the gas is effectively increased, and the gas sensor has higher test sensitivity compared with a gas sensor prepared by taking the zinc oxide as a sensitive material.
3) The invention further increases the gas adsorption area by spin coating the gas sensitive materials on the upper and lower bottom surfaces of the metal surfaces of the 25 cylindrical side walls, thereby effectively ensuring the test sensitivity of the gas sensor. In addition, the gas sensor based on the substrate integrated waveguide resonator can conveniently change the conductive gas-sensitive material which is spin-coated on the metal surface of the cylindrical side wall, and the gas sensor sensitive to different gases is prepared.
4) The sensor disclosed by the invention is smaller in size, lower in thickness of the substrate material, more beneficial to installation of the sensor in a complex environment and more convenient to carry. In addition, the gas sensor fully utilizes the advantages of high quality factor, low loss and the like of the substrate integrated waveguide resonator, and can effectively increase the distance of wireless test.
Drawings
FIG. 1 is a top view of a sensor structure of the present invention;
FIG. 2 is a bottom view of the sensor structure of the present invention;
FIG. 3 is an anatomical view A-A of FIG. 1;
FIG. 4 is a top view of FIG. 1 at 2;
FIG. 5 is an anatomical view of B-B of FIG. 1 at 2;
FIG. 6 is a schematic view of a sensor manufacturing process;
FIG. 7 is a schematic diagram of the microwave scattering test of the present invention;
in the figure: the method comprises the following steps of 1, a slot antenna, 2, a gas sensitive structure, 3, a side wall metal cylinder through hole of a substrate integrated waveguide, 4, an upper surface metal layer, 5, a lower surface metal layer, 6, a cylinder hole, 7, a gas sensitive material coating, 9-14, 15, a wireless passive gas sensor, 16, an interrogation antenna, 17, a frequency sweeping emission signal, 18, an echo reflection signal, 19, a gas test platform and a wireless passive gas sensor, wherein the first layer to the sixth layer of the LTCC ceramic are respectively represented.
Detailed Description
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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.
As shown in fig. 1, 2 and 3, the LTCC-based substrate integrated waveguide type wireless passive gas sensor comprises an upper surface metal layer 4, a lower surface metal layer 5 and an LTCC alumina ceramic chip arranged in the middle, wherein the upper surface metal layer 4, the lower surface metal layer 5 and the LTCC alumina ceramic chip form a substrate, a circle of substrate integrated waveguide side wall metal cylindrical through hole 3 is formed in the periphery of the substrate, silver paste is filled in the substrate integrated waveguide side wall metal cylindrical through hole 3, a gas sensitive structure 2 is arranged in the middle of the substrate, and a slot antenna 1 is arranged on the surface of the upper surface metal layer 4.
As shown in fig. 4 and 5, the gas sensitive structure 2 comprises a cylindrical hole 6 formed in an LTCC alumina ceramic sheet, wherein a layer of silver paste is coated on the inner surface of the cylindrical hole 6, and a graphene oxide coating 7 is coated on the outer side of the silver paste.
The LTCC alumina ceramic sheet is provided with 6 layers.
As shown in fig. 6, a method for manufacturing a substrate integrated waveguide type wireless passive gas sensor based on LTCC specifically includes the following steps:
1) firstly, 6 pieces of LTCC green tapes are prepared, the numbers from the first layer to the sixth layer are 9-14, 9-11 three layers of LTCC green tapes are laminated for 20 minutes under the parameters of 70 ℃ and 21MPa, and then 25 cylinders are cut off at the middle position of the laminated 9-11 layers of green tapes.
2) And continuously laminating 9-11 layers of the cylindrical green porcelain tapes and 12-14 layers of the cylindrical green porcelain tapes, wherein the lamination is carried out for 20 minutes under the condition that the lamination parameters are 70 ℃ and 21 MPa.
3) Cutting off a series of small cylindrical through holes at the position of one circle on the peripheral side of the laminated 9-14 layers of green porcelain tapes, filling the cut small cylindrical through holes with silver paste, and brushing the inner walls of the 25 small cylindrical through holes cut off in the first step with the silver paste.
4) And (4) sintering the green porcelain tape printed with the silver paste in the third step in a high-temperature furnace at 850 ℃ to obtain 9-14 layers of cooked porcelain.
5) Printing silver paste on the upper surfaces of 9-14 layers of the porcelain by adopting a screen printing process, and sintering at 850 ℃ in a high-temperature furnace to obtain an upper metal surface of the substrate integrated waveguide and a slot antenna structure; and printing silver paste on the lower surfaces of the 9-14 layers of the porcelain, and sintering to obtain the lower metal surface of the substrate integrated waveguide.
6) Preparing graphene oxide, namely adding 100mL of concentrated sulfuric acid and 10mL of phosphoric acid into a three-necked bottle in sequence; placing the mixed acid in an ice-water bath, adding 0.8g of crystalline flake graphite and 5g of potassium permanganate, and stirring for 45 min; placing the mixture in a constant temperature water tank of 45-55 ℃ to be stirred for 35min, and then placing the mixture in a constant temperature water tank of 60 ℃ to react for 16h, wherein the mixture is dark green; dropwise adding 50mL of 5% hydrogen peroxide, and fully stirring until the mixture turns golden yellow; transferring the product to a beaker, standing at normal temperature, cooling, and washing with deionized water for multiple times until the product is neutral; and (3) drying the washed product in a drying oven at 60 ℃, wherein the obtained product is graphene oxide.
7) And doping the graphene oxide prepared in the sixth step with zinc oxide in a mass ratio of 5%, uniformly grinding the doped graphene oxide and the zinc oxide by using an agate mortar, adding a proper amount of deionized water, and preparing into slurry serving as the gas sensitive material.
8) And (4) uniformly spin-coating the gas-sensitive material prepared in the seventh step on the side walls and the lower surfaces of the 25 cylindrical holes cut out in the first step to prepare the final wireless passive gas sensor.
As shown in FIG. 7, in the operation mode of the substrate integrated wireless passive gas sensor based on microwave scattering, an interrogation antenna 16 (a coplanar waveguide-fed ultra-wideband antenna, an open-circuit waveguide antenna, etc.) emits a sweep frequency signal 17 containing the resonant frequency of the sensor, which is received by the slot antenna 1 of the metal layer 4 on the upper surface of the substrate integrated waveguide, the slot antenna couples the signal into the substrate integrated waveguide, a limit signal close to the resonant frequency of the waveguide forms a standing wave in the substrate integrated waveguide, and other frequency signals 18 are reflected back to be received by the interrogation antenna, and the resonant frequency of the echo reflected signal to the substrate integrated waveguide of the interrogation antenna is analyzed. In the working engineering of the gas sensor, after the gas sensitive structure 2 coated with graphene oxide in a spinning mode absorbs gas, the resistivity of the inner wall of the structure changes, and the resonant frequency of the substrate integrated waveguide changes according to the perturbation principle of the substrate integrated waveguide, so that the concentration change condition of the detected gas can be obtained by analyzing the resonant frequency of the substrate integrated waveguide received by the interrogation antenna by using a network analyzer.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.
Claims (1)
1. A preparation method of a substrate integrated waveguide type wireless passive gas sensor based on LTCC is characterized by comprising the following steps: the LTCC-based substrate integrated waveguide type wireless passive gas sensor comprises an upper surface metal layer (4), a lower surface metal layer (5) and an LTCC alumina ceramic chip arranged in the middle, wherein the upper surface metal layer (4), the lower surface metal layer (5) and the LTCC alumina ceramic chip form a substrate, a circle of side wall metal cylindrical through holes (3) of a substrate integrated waveguide are formed in the periphery side of the substrate, silver paste is filled in the side wall metal cylindrical through holes (3) of the substrate integrated waveguide, a gas sensitive structure (2) is arranged in the middle of the substrate, and a slot antenna (1) is arranged on the surface of the upper surface metal layer (4); the gas sensitive structure (2) comprises a cylindrical hole (6) formed in an LTCC alumina ceramic chip, a layer of silver paste is coated on the inner surface of the cylindrical hole (6), and a gas sensitive material coating (7) formed by mixing graphene oxide and zinc oxide is coated on the outer side of the silver paste; the LTCC alumina ceramic sheet is provided with 6 layers;
the preparation method comprises the following specific steps:
1) firstly, preparing 6 LTCC green ceramic tapes, wherein the numbers from the first layer to the sixth layer are 9-14, laminating 9-11 three layers of LTCC green ceramic tapes for 20 minutes at the temperature of 70 ℃ and under the pressure of 21MPa, and cutting off 25 cylinders at the middle position of the laminated 9-11 layers of green ceramic tapes;
2) continuously laminating 9-11 layers of the cylindrical green porcelain tapes and 12-14 layers of the cylindrical green porcelain tapes, wherein the lamination is carried out for 20 minutes under the condition that the lamination parameters are 70 ℃ and 21 MPa;
3) cutting a series of small cylindrical through holes at the position of one circle on the peripheral side of the laminated 9-14 layers of green porcelain tapes, filling silver paste into the cut small cylindrical through holes, and brushing the inner walls of the 25 small cylinders cut in the first step with the silver paste;
4) placing the green porcelain tape printed with the silver paste in the third step into a high-temperature furnace to be sintered at 850 ℃ to obtain 9-14 layers of cooked porcelain;
5) printing silver paste on the upper surfaces of 9-14 layers of the porcelain by adopting a screen printing process, and sintering at 850 ℃ in a high-temperature furnace to obtain an upper metal surface of the substrate integrated waveguide and a slot antenna structure; printing silver paste on the lower surfaces of the 9-14 layers of the cooked porcelain, and sintering to obtain a lower metal surface of the substrate integrated waveguide;
6) preparing graphene oxide, namely adding 100mL of concentrated sulfuric acid and 10mL of phosphoric acid into a three-necked bottle in sequence; placing the mixed acid in an ice-water bath, adding 0.8g of crystalline flake graphite and 5g of potassium permanganate, and stirring for 45 min; placing the mixture in a constant temperature water tank of 45-55 ℃ to be stirred for 35min, and then placing the mixture in a constant temperature water tank of 60 ℃ to react for 16h, wherein the mixture is dark green; dropwise adding 50mL of 5% hydrogen peroxide, and fully stirring until the mixture turns golden yellow; transferring the product to a beaker, standing at normal temperature, cooling, and washing with deionized water for multiple times until the product is neutral; drying the washed product in a drying oven at 60 ℃ to obtain a product, namely graphene oxide;
7) doping the graphene oxide prepared in the sixth step with zinc oxide in a mass ratio of 5%, uniformly grinding the graphene oxide and the zinc oxide by using an agate mortar, adding deionized water, and preparing into slurry serving as a gas-sensitive material;
8) and (4) uniformly spin-coating the gas-sensitive material prepared in the seventh step on the side walls and the lower surfaces of the 25 cylindrical holes cut out in the first step to prepare the final wireless passive gas sensor.
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| CN108387971B (en) * | 2018-03-13 | 2019-09-20 | 清华大学 | Tunable directional couple device based on graphene and nanotube antenna array |
| CN111272831B (en) * | 2020-02-24 | 2021-10-15 | 大连理工大学 | Based on MXene/SnO2Heterojunction passive wireless ammonia gas sensor and preparation method thereof |
| RU2770861C1 (en) * | 2021-07-22 | 2022-04-22 | федеральное государственное автономное образовательное учреждение высшего образования «Московский физико-технический институт (национальный исследовательский университет)» | Thermocatalytic sensor based on ceramic mems platform and method for its manufacture |
| CN113884542B (en) * | 2021-09-06 | 2024-02-06 | 中国科学院上海硅酸盐研究所 | Wireless micro-fluidic sensor based on multilayer ceramic technology |
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| CN103675040A (en) * | 2013-11-20 | 2014-03-26 | 中北大学 | Non-contact passive gas sensor based on low-temperature co-fired ceramic technology |
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