A hydrogen sensor based on ceramic MEMS technology and a preparation method thereof

Abstract

The application discloses a hydrogen sensor based on a ceramic MEMS process and a preparation method thereof, and belongs to the technical field of hydrogen sensors. In order to improve the high strength and good heat dissipation performance of the hydrogen sensor, the application comprises a substrate, a hollow region, a triangular gas sensitive region, a measurement outer lead, a heating sensitive electrode and a pad; the upper region and the lower region in the substrate are of the same structure, the upper region serves as a sensitive region, and the lower region serves as a compensation region; the structure of the upper region and the lower region comprises the triangular gas sensitive region arranged at the center of the region, the outer side of the side of the triangular gas sensitive region is respectively arranged with the hollow region, the triangular gas sensitive region is covered on the heating sensitive electrode, and the heating sensitive electrode is connected with the pad through the measurement outer lead; the pad is arranged relative to the top corner line of the triangular gas sensitive region and is arranged between the hollow regions; and the heating sensitive electrode is a vortex line disc structure. The application has high reliability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen sensors, and particularly relates to a hydrogen sensor based on a ceramic MEMS process and a preparation method thereof. BACKGROUND

[0002] With the rapid development of hydrogen energy, hydrogen as a clean energy plays an increasingly important role in the energy structure. However, the high flammability and high explosiveness of hydrogen require strict monitoring and management during the production, storage and use of hydrogen energy. Therefore, it is of great significance to develop a hydrogen sensor with high sensitivity, high stability and high reliability for the safety of hydrogen energy.

[0003] At present, there are various hydrogen sensors on the market, such as electrochemical hydrogen sensors, catalytic combustion hydrogen sensors, infrared hydrogen sensors, etc. These sensors can meet the demand of hydrogen detection to some extent, but still have some limitations. For example, metal oxide semiconductor sensors are easily disturbed by other gases at high temperatures, electrochemical sensors have a short service life, and catalytic combustion sensors have high requirements for environmental conditions. In addition, the stability and reliability of existing sensors in harsh environments such as chemical industry, humidity and acid-base corrosion still need to be improved. SUMMARY

[0004] The problem to be solved by the present application is to improve the high strength and good heat dissipation performance of the hydrogen sensor, and a hydrogen sensor based on a ceramic MEMS process and a preparation method thereof are proposed.

[0005] To achieve the above-mentioned purpose, the technical scheme is as follows:

[0006] A hydrogen sensor based on a ceramic MEMS process, comprising a substrate, a hollow area, a triangular gas sensitive area, a measurement outer lead, a heating sensitive electrode and a pad;

[0007] The upper region and the lower region in the substrate have the same structure, the upper region serves as a sensitive region, and the lower region serves as a compensation region; the structure of the upper region and the lower region comprises a triangular gas sensitive area arranged at the center of the region, the outer side of the side of the triangular gas sensitive area is respectively arranged with a hollow area, the triangular gas sensitive area is covered on the heating sensitive electrode, and the heating sensitive electrode is connected to the pad through the measurement outer lead;

[0008] The pad is arranged relative to the top angle line of the triangular gas sensitive area and between the hollow areas;

[0009] The heating sensitive electrode is a vortex-shaped line disc structure.

[0010] Further, the shape of the hollow area is an isosceles trapezoid.

[0011] Further, the disc structure of the heating sensitive electrode constitutes an incircle of the triangular gas sensitive region.

[0012] A preparation method of a hydrogen sensor based on a ceramic MEMS process, comprising the following steps:

[0013] S1. Shearing high-purity aluminum foil according to the size of the substrate to obtain a substrate basic outline;

[0014] S2. Placing the high-purity aluminum foil in a sulfuric acid solution of a certain concentration, using an anodic oxidation method to additively manufacture an aluminum oxide film on the aluminum foil, and then using a MEMS micro-processing process to micro-process the aluminum oxide film to form a substrate with a hollow region;

[0015] S3. Using a magnetron sputtering film forming technology, using platinum of 99.99% purity as a target material, sputtering a 1-2 micrometer platinum film on the substrate obtained in step S2, and then using a thin film lithography etching process to manufacture a heating sensitive electrode, a measurement external lead and a pad;

[0016] S4. Measuring a certain mass of an aluminum oxide skeleton, a multi-layer titanium carbide, a graphdiyne quantum dot, a dispersing agent and a terpineol to prepare a stable slurry, and then printing the slurry on the heating sensitive electrode obtained in step S3 to prepare a triangular gas sensitive region;

[0017] S5. Preparing a lead nitrate solution of a certain concentration, covering a desensitizer on the triangular gas sensitive region in the lower region by drop coating to perform desensitization treatment, and then performing sintering treatment, repeating several times to complete the preparation of a hydrogen sensor based on a ceramic MEMS process.

[0018] Further, the thickness of the high-purity aluminum foil in step S1 is 0.25-0.3 mm, and the substrate basic outline is a rectangle.

[0019] Further, in step S2, the concentration of the sulfuric acid solution is 5wt%, and the process parameters of anodic oxidation are a constant voltage of 27-29V and a working time of 4-7h.

[0020] Further, in step S3, the line width of the vortex line of the heating sensitive electrode is 20 micrometers, and the line spacing is 80 micrometers; the pad is designed at the edge of the substrate in a symmetrical distribution manner; the thin film lithography etching process uses ion beam etching, the etching gas is argon, the etching rate is 20 nanometers per minute, the gold film not protected by the photoresist is etched away, and finally the photoresist is removed to obtain the heating sensitive electrode, the measurement external lead and the pad.

[0021] Further, the specific implementation method of step S4 comprises the following steps:

[0022] S4.1. Nanoscale alumina, multilayer titanium carbide, graphdiyne quantum dots, polyethylene glycol, terpineol are weighed according to a mass ratio of 70:15:5:3:7, the particle size of the nanoscale alumina is 30nm-50nm, and the particle size of the multilayer titanium carbide is 10nm-20nm;

[0023] S4.2. The weighed nanoscale alumina, multilayer titanium carbide, graphdiyne quantum dots are placed into a agate mortar, terpineol is added as a solvent, and polyethylene glycol is further added, and grinding and mixing are performed until a stable slurry is formed.

[0024] S4.3. The stable slurry is prepared on the heat-sensitive electrode obtained in step S3 by means of inkjet printing to form a triangular gas-sensitive area, and the thickness parameter of inkjet printing is 10-15 microns.

[0025] Further, the concentration of the lead nitrate solution in step S5 is 5wt%, the sintering treatment is that the desensitization treated substrate structure is placed into a sintering furnace, the furnace temperature is increased to 400-500 DEG C at a heating rate of 5 DEG C / minute, and then sintering is carried out for two hours, and then the temperature is naturally cooled to room temperature in air; the desensitization treatment and the sintering treatment are repeatedly carried out for 3-4 times, and the preparation of a hydrogen sensor based on a ceramic MEMS process is completed.

[0026] Further, the particle size of the copper powder selected as the raw material of the explosion-proof layer is 100 mesh, the copper powder is pretreated, water and volatile impurities in the copper powder are removed by heating at 150 DEG C for 3 hours in a vacuum environment, and the copper powder mixed with a binder is loaded into a mold to prepare an explosion-proof shell for being arranged at the periphery of the substrate.

[0027] The hydrogen sensor based on the ceramic MEMS process has the following beneficial effects:

[0028] The hydrogen sensor based on the ceramic MEMS process has the following beneficial effects:

[0029] The hydrogen sensor based on the ceramic MEMS process has the following beneficial effects: The hydrogen sensor based on the ceramic MEMS process adopts a ceramic alumina film manufactured based on an additive manufacturing technology and a MEMS microprocessing process as a substrate material, the substrate has a hollow structure design, good mechanical strength is ensured, heat dissipation efficiency is improved, and the performance of the sensor in a high-temperature environment is ensured. The triangular sensitive area structure design of the substrate maximizes the reduction of heat capacity in limited space, improves the response speed and sensitivity of the sensor, the vortex line sensitive electrode design reduces the interference of external electric fields, and stable work of the sensor in various environments is ensured.

[0030] The hydrogen sensor based on the ceramic MEMS process has a heating sensitive electrode located at the center of a triangular gas sensitive region of an upper part and a lower part of a substrate, and is made of a platinum thin film with a special structure through a photoetching etching process. The heating sensitive electrode in the sensor generates heat after being powered on to form a certain temperature field. The hydrogen sensitive material is closely attached to the measurement heating sensitive electrode. When the hydrogen concentration increases, the temperature field distribution changes due to the high thermal conductivity of hydrogen. The change can be detected by measuring the resistance change of the heating sensitive electrode.

[0031] The hydrogen sensor based on the ceramic MEMS process has a heating sensitive electrode located at the center of a triangular gas sensitive region of an upper part and a lower part of a substrate, and is made of a platinum thin film with a special structure through a photoetching etching process. The heating sensitive electrode in the sensor generates heat after being powered on to form a certain temperature field. The hydrogen sensitive material is closely attached to the measurement heating sensitive electrode. When the hydrogen concentration increases, the temperature field distribution changes due to the high thermal conductivity of hydrogen. The change can be detected by measuring the resistance change of the heating sensitive electrode.

[0032] The hydrogen sensor based on the ceramic MEMS process has a heating sensitive electrode located at the center of a triangular gas sensitive region of an upper part and a lower part of a substrate, and is made of a platinum thin film with a special structure through a photoetching etching process. The heating sensitive electrode in the sensor generates heat after being powered on to form a certain temperature field. The hydrogen sensitive material is closely attached to the measurement heating sensitive electrode. When the hydrogen concentration increases, the temperature field distribution changes due to the high thermal conductivity of hydrogen. The change can be detected by measuring the resistance change of the heating sensitive electrode.

[0033] The hydrogen sensor based on the ceramic MEMS process has a heating sensitive electrode located at the center of a triangular gas sensitive region of an upper part and a lower part of a substrate, and is made of a platinum thin film with a special structure through a photoetching etching process. The heating sensitive electrode in the sensor generates heat after being powered on to form a certain temperature field. The hydrogen sensitive material is closely attached to the measurement heating sensitive electrode. When the hydrogen concentration increases, the temperature field distribution changes due to the high thermal conductivity of hydrogen. The change can be detected by measuring the resistance change of the heating sensitive electrode. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The structure diagram of the hydrogen sensor based on the ceramic MEMS process is shown in the figure;

[0035] Figure 2 The structure diagram of the upper region of the hydrogen sensor based on the ceramic MEMS process is shown in the figure;

[0036] Figure 3 The structure diagram of the substrate and the hollow region of the hydrogen sensor based on the ceramic MEMS process is shown in the figure;

[0037] In the figure, 1 is the substrate, 2 is the hollow region, 3 is the triangular gas sensitive region, 4 is the measurement outer lead, 5 is the heating sensitive electrode, and 6 is the solder pad. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application, i.e., the specific embodiments described are only a part of the embodiments of the present application, but not all the specific embodiments. The components of the specific embodiments of the present application generally described and shown in the accompanying drawings can be arranged and designed in various different configurations, and the present application can also have other embodiments.

[0039] Therefore, the detailed description of the specific embodiments of the present application provided below in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected specific embodiments of the present application. Based on the specific embodiments of the present application, all other specific embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] In order to further understand the inventive content, characteristics and effects of the present application, the following specific embodiments are exemplified, and the accompanying drawings are used for the description. Figure 1 - the accompanying drawings Figure 3 The detailed description is as follows:

[0041] Embodiment 1:

[0042] A hydrogen sensor based on ceramic MEMS technology, comprising a substrate 1, a hollow area 2, a triangular gas sensitive area 3, a measurement outer lead 4, a heating sensitive electrode 5 and a pad 6;

[0043] The upper region and the lower region in the substrate 1 have the same structure, the upper region serves as a sensitive region, and the lower region serves as a compensation region; the structure of the upper region and the lower region comprises a triangular gas sensitive area 3 arranged at the center of the region, the outer side of the edge of the triangular gas sensitive area 3 is respectively arranged with a hollow area 2, the triangular gas sensitive area 3 is covered on the heating sensitive electrode 5, and the heating sensitive electrode 5 is connected to the pad 6 through the measurement outer lead 4 respectively;

[0044] The pad 6 is arranged relative to the top angle line of the triangular gas sensitive area 3 and between the hollow areas 2;

[0045] The heating sensitive electrode 5 is a vortex line disc structure.

[0046] Further, the shape of the hollow area 2 is isosceles trapezoidal.

[0047] Further, the disc structure of the heating sensitive electrode 5 constitutes an incircle of the triangular gas sensitive area 3.

[0048] Further, the heating sensitive electrode is located at the center of the triangular gas sensitive area on the upper and lower parts of the substrate, which is made of platinum thin film with a specific structure by photolithography etching process. The heating sensitive electrode in the sensor generates heat after being powered on, forming a certain temperature field. The hydrogen sensitive material is closely attached to the measurement heating sensitive electrode. When the hydrogen concentration increases, the temperature field distribution changes due to the high thermal conductivity of hydrogen. This change can be detected by measuring the resistance change of the heating sensitive electrode.

[0049] Embodiment 2:

[0050] A preparation method of a hydrogen sensor based on a ceramic MEMS process according to Embodiment 1, comprising the following steps:

[0051] S1. Shearing high-purity aluminum foil according to the size of the substrate to obtain a substrate basic outline;

[0052] Further, the thickness of the high-purity aluminum foil in step S1 is 0.25-0.3 mm, and the substrate basic outline is a rectangle.

[0053] S2. Placing the high-purity aluminum foil in a sulfuric acid solution of a certain concentration, using an anodization method to additively manufacture an aluminum oxide film on the aluminum foil, and then using a MEMS microfabrication process to microfabricate the substrate with a hollow area on the aluminum oxide film;

[0054] Further, the concentration of the sulfuric acid solution in step S2 is 5wt%, and the process parameters of the anodization process are a constant voltage of 27-29V and a working time of 4-7h;

[0055] Further, the process parameters of the MEMS microfabrication process are using a stereolithography (SLA) technology to prepare a photocuring slurry, mixing ceramic aluminum oxide powder and photosensitive resin containing acrylate at a mass ratio of 4:6, performing ultrasonic dispersion for 40 minutes at an ultrasonic frequency of 30kHz and a power of 800W to uniformly disperse the aluminum oxide powder in the resin to form a stable printing slurry; the substrate is designed as two parts with the same upper and lower structure, and the hollow area is combined as a whole to be manufactured at one time; after the substrate and the hollow area are manufactured, sintering treatment is performed in a high-temperature furnace; first, the furnace temperature is raised to 600℃ at a heating rate of 5℃ / min, and then kept at this temperature for 2 hours to remove the photocuring resin; then, the temperature is continuously raised to 1500℃ at a heating rate of 10℃ / min, and kept at 1500℃ for 4 hours to fully sinter the aluminum oxide particles and improve the density and strength of the substrate;

[0056] S3. Using a magnetron sputtering film forming technology, taking platinum with a purity of 99.99% as the target material, sputtering it onto the substrate obtained in step S2 to form a platinum film with a thickness of 1-2 microns, and then using a thin film photolithography etching process to manufacture a heating sensitive electrode, a measurement external lead, and a pad.

[0057] Further, the sputtering power is between 100-300W;

[0058] Further, in step S3, the line width of the vortex line of the heating sensitive electrode is 20 microns, and the line spacing is 80 microns; the pads are designed at the edge of the substrate in a symmetrical distribution manner; the thin film photoetching etching process adopts ion beam etching, the etching gas is argon, the etching rate is 20 nanometers per minute, the gold film not protected by the photoresist is etched away, and finally the photoresist is removed to obtain the heating sensitive electrode, the measurement outer lead and the pad.

[0059] S4. A certain mass of alumina skeleton, multi-layer titanium carbide, graphite yne quantum dots, dispersant, and terpineol are weighed to prepare a stable slurry, and then the slurry is printed on the heating sensitive electrode obtained in step S3 to prepare a triangular gas sensitive area;

[0060] Further, the specific implementation method of step S4 includes the following steps:

[0061] S4.1. Nanoscale alumina, multi-layer titanium carbide, graphite yne quantum dots, polyethylene glycol, and terpineol are weighed according to a mass ratio of 70:15:5:3:7, the particle size of the nanoscale alumina is 30-50 nm, and the particle size of the multi-layer titanium carbide is 10-20 nm;

[0062] S4.2. The weighed nanoscale alumina, multi-layer titanium carbide, and graphite yne quantum dots are put into an agate mortar, terpineol is added as a solvent, polyethylene glycol is added, and grinding and mixing are performed until a stable slurry is formed;

[0063] S4.3. The stable slurry is printed on the heating sensitive electrode obtained in step S3 to prepare a triangular gas sensitive area with a thickness parameter of 10-15 microns.

[0064] S5. A lead nitrate solution with a certain concentration is prepared, a desensitizer is coated on the triangular gas sensitive area in the lower area by drop coating to perform desensitization treatment, and then sintering treatment is performed, and after repeating several times, a hydrogen sensor based on a ceramic MEMS process is prepared.

[0065] Further, in step S5, the concentration of the lead nitrate solution is 5wt%; the sintering treatment is to place the substrate structure after desensitization treatment into a sintering furnace, to raise the furnace temperature to 400-500℃ at a heating rate of 5℃ / min, and to sinter for two hours, and then to naturally cool to room temperature in air; the desensitization treatment and the sintering treatment are repeated 3-4 times to complete the preparation of a hydrogen sensor based on a ceramic MEMS process.

[0066] Further, the desensitizer uses a 5% concentration of lead nitrate solution to print ink on the sensitive material and is heated to decompose lead oxide to inhibit hydrogen production catalytic combustion reaction;

[0067] Further, the particle size of 100 mesh copper powder is selected as the raw material of the explosion-proof layer, the copper powder is pretreated, heated at 150℃ for 3 hours in a vacuum environment to remove water and volatile impurities in the powder, and the copper powder mixed with the binder is loaded into the mold to prepare the explosion-proof shell for setting on the periphery of the base.

[0068] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0069] Although the present application has been described with reference to specific implementations, various modifications and changes can be made thereto without departing from the scope of the present application as set forth in the claims. In particular, features of the specific implementations disclosed herein can be combined with each other, unless there are structural contradictions, and the combinations are not described in the specification only for the purpose of omitting the description and saving resources. Therefore, the present application is not limited to the specific implementations disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for fabricating a hydrogen sensor based on ceramic MEMS technology, wherein the hydrogen sensor based on ceramic MEMS technology includes a substrate (1), a hollow area (2), a triangular gas sensitive area (3), a measurement lead (4), a heating sensitive electrode (5), and a pad (6). The upper and lower regions within the substrate (1) have the same structure, with the upper region serving as the sensitive region and the lower region serving as the compensation region. The structure of the upper and lower regions includes a triangular gas sensitive region (3) located at the center of the region. Hollowed-out regions (2) are arranged on the outer sides of the sides of the triangular gas sensitive region (3). The triangular gas sensitive region (3) covers the heating sensitive electrode (5), and the heating sensitive electrode (5) is connected to the pads (6) through the external measurement leads (4). The pad (6) is arranged relative to the apex line of the triangular gas-sensitive region (3) and is arranged between the hollowed-out regions (2); The heating sensitive electrode (5) has a spiral disk structure; Its features are, Includes the following steps: S1. Cut the high-purity aluminum foil according to the dimensions of the substrate to obtain the basic shape of the substrate; S2. High-purity aluminum foil is placed in a sulfuric acid solution of a certain concentration, and an aluminum oxide film is additively manufactured on the aluminum foil by anodizing. Then, a substrate with hollow areas is formed on the aluminum oxide film by MEMS micromachining process. S3. Using magnetron sputtering technology, 99.99% pure platinum is sputtered onto the substrate obtained in step S2 to form a 1-2 micrometer platinum film, which is then fabricated into a heating sensitive electrode, measurement lead wire and pad through thin film photolithography etching process. S4. Weigh a certain mass of alumina framework, multilayer titanium carbide, graphdiyne quantum dots, dispersant, and terpineol to prepare a stable slurry, and then use inkjet printing to prepare a triangular gas-sensitive region on the heating sensitive electrode obtained in step S3. S5. Prepare a lead nitrate solution of a certain concentration, and apply the desensitizing agent to the triangular gas-sensitive area in the lower region by drop coating to perform desensitization treatment. Then, perform sintering treatment. After repeating this process several times, a hydrogen sensor based on ceramic MEMS technology is fabricated.

2. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 1, characterized in that, In step S1, the thickness of the high-purity aluminum foil is 0.25-0.3 mm, and the basic shape of the substrate is rectangular.

3. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 2, characterized in that, In step S2, the concentration of the sulfuric acid solution is 5 wt%, and the process parameters for anodizing are a constant voltage of 27-29 V and a working time of 4-7 h.

4. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 3, characterized in that, In step S3, the linewidth of the spiral line of the heating sensitive electrode is 20 micrometers and the line spacing is 80 micrometers; the pads are designed at the edge of the substrate and are symmetrically distributed; the thin film photolithography etching process uses ion beam etching, the etching gas is argon, and the etching rate is 20 nanometers / minute to etch away the platinum film that is not protected by photoresist. Finally, the photoresist is removed to obtain the heating sensitive electrode, the measurement lead wire and the pad.

5. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 4, characterized in that, The specific implementation method of step S4 includes the following steps: S4.

1. Weigh nano-sized alumina, multilayer titanium carbide, graphdiyne quantum dots, polyethylene glycol, and terpineol according to a mass ratio of 70:15:5:3:7, wherein the nano-sized alumina has a particle size of 30nm-50nm and the multilayer titanium carbide has a particle size of 10nm-20nm. S4.

2. Place the weighed nano-sized alumina, multilayer titanium carbide, and graphylene quantum dots into an agate mortar, add terpineol as a solvent, then add polyethylene glycol, and grind and mix until a stable slurry is formed. S4.

3. The thickness parameter of the inkjet printing of the triangular gas-sensitive region on the heating-sensitive electrode obtained in step S3 is 10-15 micrometers. The stabilized slurry is prepared by inkjet printing.

6. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 5, characterized in that, In step S5, the concentration of lead nitrate solution is 5 wt%. The sintering process involves placing the desensitized substrate structure into a sintering furnace, raising the furnace temperature to 400-500℃ at a heating rate of 5℃ / min, and sintering at a constant temperature for two hours. Then, the substrate is naturally cooled to room temperature in air. The desensitization and sintering processes are repeated 3-4 times to complete the fabrication of a hydrogen sensor based on ceramic MEMS technology.

7. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 6, characterized in that, Copper powder with a particle size of 100 mesh was selected as the raw material for the explosion-proof layer. The copper powder was pretreated and heated at 150°C for 3 hours in a vacuum environment to remove moisture and volatile impurities from the powder. The copper powder mixed with binder was then loaded into a mold to prepare the explosion-proof shell, which was used to set on the periphery of the base.

8. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 7, characterized in that, The hollow area (2) is an isosceles trapezoid.

9. The method for fabricating a hydrogen sensor based on ceramic MEMS technology according to claim 8, characterized in that, The disk structure of the heating sensitive electrode (5) forms the inscribed circle of the triangular gas sensitive region (3).

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