Array gas sensor and preparation method thereof

Abstract

The present invention provides an array gas sensor and a preparation method thereof, wherein the array gas sensor comprises a plurality of gas-sensitive units, which are arranged in an array, and each gas-sensitive unit comprises: a zirconia substrate; a heating electrode, which is arranged on the surface of the zirconia substrate, the heating electrode has an unclosed annular structure, and forms a first region inside the annular structure, and forms a second region outside the annular structure; a temperature measuring electrode, which is arranged on the surface of the zirconia substrate located in the second region; an insulating layer, which covers the surface of the heating electrode and the temperature measuring electrode away from the zirconia substrate; a plurality of measuring electrodes, which are arranged in a toothed distribution on the surface of the insulating layer located in the first region; and a gas-sensitive film, which covers the surface of the insulating layer between the plurality of measuring electrodes and is electrically connected to the measuring electrodes. The present invention integrates three kinds of electrodes on the zirconia substrate, thereby realizing the miniaturization, integration and practicality of the array gas sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of gas sensors, and in particular to an array type gas sensor and a preparation method thereof. Background Art

[0002] In the field of gas sensing, traditional semiconductor sensors, electrochemical sensors and optical gas analyzers are widely used. Although a single independent detector can work effectively in specific occasions, its detection range, cross-sensitivity and environmental adaptability often cannot meet actual needs in complex environments or when detecting mixed gases with complex components.

[0003] Micro-electromechanical system (MEMS) gas sensors respond to low concentrations of gas by converting the type and concentration of gas into measurable electrical signals. Setting up a sensor array on a MEMS gas sensor can detect single or multiple target gases through multiple sensing units, thereby improving the accuracy of detection and the type of gas identified. However, when related technologies attempt to integrate sensors on a substrate chip, it is difficult to integrate multiple sensors, and it is difficult to accurately control and measure the operating temperature of the heating electrode.

[0004] In addition, when the array-type micro-hotplate gas sensor prepared by the related technology performs gas-sensitive detection, the electrode film is easy to fall off during repeated heating, causing damage to the array-type micro-hotplate gas sensor and making it difficult to work continuously. Summary of the invention

[0005] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present invention provides an array gas sensor and a preparation method thereof.

[0006] According to an embodiment of one aspect of the present invention, there is provided an array gas sensor, comprising a plurality of gas-sensitive units, which are distributed in an array, and each gas-sensitive unit comprises: a zirconia substrate; a heating electrode, which is arranged on the surface of the zirconia substrate, the heating electrode having an unclosed annular structure, and forming a first region inside the annular structure and a second region outside the annular structure; a temperature measuring electrode, which is arranged on the surface of the zirconia substrate located in the second region; an insulating layer, which covers the surfaces of the heating electrode and the temperature measuring electrode away from the zirconia substrate; a plurality of measuring electrodes, which are arranged in a toothed distribution on the surface of the insulating layer located in the first region; and a gas-sensitive film, which covers the surface of the insulating layer between the plurality of measuring electrodes and is electrically connected to the measuring electrodes.

[0007] According to an embodiment of the present invention, in a direction parallel to the zirconia substrate, a first spacing distance between the temperature measuring electrode and the heating electrode is equal to a second spacing distance between the heating electrode and the measuring electrode; the first spacing distance and the second spacing distance are 5-15 μm.

[0008] According to an embodiment of the present invention, the material of the heating electrode and the temperature measuring electrode includes platinum, and the thickness of the heating electrode and the temperature measuring electrode is 80~120nm; the thickness of the zirconium oxide substrate is 80~120μm; the material of the insulating layer includes oxide, and the thickness of the insulating layer is 30~50nm; the material of the measuring electrode includes gold, and the thickness of the measuring electrode is 80~120nm; the material of the gas sensitive film includes metal oxide doped with sensitizing elements, wherein the sensitizing elements include at least one of platinum, gold, indium and silver; the line width range of the heating electrode, the temperature measuring electrode and the measuring electrode is each independently 10~40μm, preferably 15~30μm.

[0009] According to an embodiment of the present invention, the number of gas sensing units is 16.

[0010] According to an embodiment of the present invention, the zirconia substrate has a plurality of through-holes to form a bridge structure, the bridge structure includes a plurality of cantilever beams and a suspended membrane portion located between the plurality of cantilever beams, the cantilever beams providing support for the suspended membrane portion; the heating electrode, the temperature measuring electrode, the insulating layer, the measuring electrode and the gas sensitive film are respectively located on the suspended membrane portion.

[0011] According to an embodiment of the present invention, the heating electrode and the temperature measuring electrode are arranged coplanarly with the measuring electrode, and the heating electrode and the temperature measuring electrode are not in contact with the measuring electrode.

[0012] According to an embodiment of another aspect of the present invention, there is provided a method for preparing an array gas sensor as described above, comprising: forming a patterned photoresist mask on the surface of a zirconia substrate; forming a heating electrode and a temperature measuring electrode on the surface of the zirconia substrate by magnetron sputtering under the protection of the photoresist mask; sequentially forming an insulating layer and a measuring electrode on the surfaces of the heating electrode and the temperature measuring electrode away from the zirconia substrate by overlay; placing a gas-sensitive slurry in an electrostatic micro-spraying device, and driving the gas-sensitive slurry to deposit on the surface of the insulating layer between a plurality of measuring electrodes in a stretching manner under the action of an electric field; and patterning the gas-sensitive slurry on the surface of the insulating layer by laser direct writing to form a gas-sensitive film, thereby obtaining an array gas sensor.

[0013] According to an embodiment of the present invention, the intensity of the electric field is 0.5~2.5kV, preferably 1~2kV, and the power of laser direct writing is 0.1~1W; forming a patterned photoresist mask on the surface of the zirconia substrate includes: spin coating photoresist on the surface of the zirconia substrate, and sequentially performing soft baking, curing, exposure, post-baking, flooding, and development treatment; the soft baking temperature is 90~100°C, and the soft baking time is 180s; the exposure time is 90~200s.

[0014] According to an embodiment of the present invention, after the heating electrode, the temperature measuring electrode, the insulating layer and the measuring electrode are formed in sequence, the method further includes: hollowing out the zirconium oxide substrate by laser, and during the hollowing out etching, the galvanometer light emission distance is 12.1-14.4 mm.

[0015] According to an embodiment of the present invention, the gas-sensitive slurry includes a photocuring agent, a cross-linking agent, a leveling agent, a metal oxide powder doped with a sensitizing element, and an organic solution; the photocuring agent includes polyurethane acrylate, the cross-linking agent includes at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; the leveling agent includes phosphate-modified acrylate.

[0016] According to the embodiments of the present invention, the present invention uses a zirconium oxide substrate as a substrate material, and utilizes its thermal expansion coefficient to be close to that of the gas-sensitive film material and the metal electrode material, thereby effectively improving the situation where the electrode and the gas-sensitive film are easy to fall off, and extending the service life of the array gas sensor. On the basis of achieving good contact between the electrode and the substrate, the present invention divides the heating electrode and the temperature measuring electrode into zones, so that the heating electrode provides a more uniform heating zone for the first zone, which helps to more accurately control the operating temperature of the array gas sensor, and uses the temperature measuring electrode to monitor the actual temperature of the heating zone, which helps to improve the accuracy of the measured temperature and improve the centralization of the heating power. The present invention integrates multiple gas-sensitive units on a chip, thereby realizing the miniaturization, integration and practicality of the array gas sensor, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1a A top view of a gas sensing unit of an array gas sensor according to an embodiment of the present invention is shown;

[0018] Figure 1b A cross-sectional view of a gas sensing unit of an array gas sensor according to an embodiment of the present invention is shown;

[0019] Figure 2 A flow chart showing a method for preparing an array gas sensor according to an embodiment of the present invention;

[0020] Figure 3 A curve diagram showing the exposure time and photolithography line width of an array gas sensor according to an embodiment of the present invention is shown;

[0021] Figure 4Optical micrographs of the cured line width and morphology of the gas-sensitive slurry under laser direct writing at different powers in the embodiment of the present invention are shown, wherein a is an optical micrograph at a power of 0.05 W, b is an optical micrograph at a power of 0.1 W, c is an optical micrograph at a power of 0.15 W, d is an optical micrograph at a power of 0.3 W, e is an optical micrograph at a power of 0.45 W, f is an optical micrograph at a power of 0.6 W, g is an optical micrograph at a power of 0.75 W, and h is an optical micrograph at a power of 0.9 W;

[0022] Figure 5 A curve diagram showing the relationship between the laser etching light emission distance and the aperture size of the array type gas sensor according to the embodiment of the present invention is shown;

[0023] Figure 6 A flow chart showing the preparation of an array gas sensor according to an embodiment of the present invention is shown;

[0024] Figure 7 The cross-sectional micrographs of the photocuring conditions of the gas-sensitive films of the gas-sensitive units of Examples 1 to 5 of the present invention at 10 μm are shown, wherein a is a cross-sectional micrograph of Example 1, b is a cross-sectional micrograph of Example 2, c is a cross-sectional micrograph of Example 3, d is a cross-sectional micrograph of Example 4, and e is a cross-sectional micrograph of Example 5;

[0025] Figure 8 The graph shows the response time of each unit of the 16-unit Sr / SnO2 gas sensor array of Example 1 of the present invention to 100 ppm ethanol at 400° C.;

[0026] Fig. 9 The graphs show the response of each unit of the 16-unit Sr / SnO2 array gas sensor of Example 1 of the present invention to 0.1ppm, 1ppm, 10ppm, 50ppm and 100ppm ethanol concentrations at 400°C;

[0027] Fig.10a The pulse curves of the array gas sensors prepared in Examples 2 to 5 of the present invention changing with time between 200 and 400° C. are shown;

[0028] Fig.10b The response and recovery curves of the array gas sensors prepared in Examples 2 to 5 of the present invention to 500 ppb ethanol concentration under pulse temperature modulation of 200 to 400° C. are shown.

[0029] [Description of Reference Numerals]

[0030] 1-zirconia substrate;

[0031] 11-Hollowout;

[0032] 12-bridge structure;

[0033] 121-cantilever beam;

[0034] 122-suspensory membrane;

[0035] 2- Heating electrode;

[0036] 3- First area;

[0037] 4- Second area;

[0038] 5- Temperature measuring electrode;

[0039] 6-Insulation layer;

[0040] 7- Measuring electrodes;

[0041] 8-gas sensitive membrane;

[0042] W1-first spacing distance;

[0043] W2 - second spacing distance. DETAILED DESCRIPTION

[0044] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0045] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0046] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0047] In the present invention, the term "laser direct writing" refers to the use of a relatively concentrated laser beam to directly perform patterning on a zirconia substrate, which can achieve high pattern accuracy (sub-micron level or finer) through non-contact processing.

[0048] The research of MEMS gas sensors mainly adopts silicon-based technology (preparing silicon wafers first, and then carrying out oxidation, photolithography, doping, metallization, packaging and other processes in sequence). The prepared micro-hotplates and their array structures are usually divided into two typical structures: micro-hot film type and micro-hot bridge type. Micro-hot film type is also called closed film type, while micro-hot bridge type is also called cantilever beam type or suspended bridge type. Since semiconductor metal oxides need to be heated to show good gas sensitivity, microstructure sensing units are widely used in the development of gas sensors and arrays due to their advantages of low heating power consumption. The process of manufacturing MEMS micro-hotplate gas sensors mainly includes two important steps: micromachining and micro-film formation. Micromachining of silicon surface is mainly aimed at the dielectric film on the silicon surface, and functional patterns are prepared through processes such as photolithography and selective etching; bulk silicon etching processes the silicon substrate in three dimensions, and uses the difference in etching rate (anisotropy) of different crystal directions of single crystal silicon to manufacture micro-nano structures with high aspect ratio.

[0049] At present, the research on gas sensor arrays is mainly divided into two aspects: one is to integrate multiple identical or different sensors on the same substrate chip to form a sensor array to improve the detection accuracy, variety and selectivity of gas sensors; the other is to integrate signal processing circuits and multiple sensors on the same chip to build a monolithic fully integrated sensing system. For example, due to the complex process and diversity of sensitive materials, the micro-hotplate gas sensor array integrates multiple sensitive units on one chip to integrate an array gas sensor. Each unit in the array is called a sensitive unit or sensor unit. Related technologies use silicon-based surface micromachining technology to manufacture a silicon-based 4-unit micro-hotplate gas sensor as a platform for studying microscale effects to determine the microscale dependence of power consumption on temperature. However, during the preparation and use of the silicon-based 4-unit micro-hotplate gas sensor, due to repeated thermal shock, it is easier to cause the electrode film to fall off, making it difficult to use continuously. The related technology also proposed a multi-dimensional tunable temperature modulation method for chemical microsensor arrays to determine the optimal working temperature conditions and analyze a variety of sensitive materials through cyclic temperature modulation. By adjusting the temperature modulation frequency and sampling frequency, the repeatability and cross-selectivity of the target gas were improved.

[0050] Although the MEMS technology used in the related art has made great progress in the preparation of array micro-hotplate gas sensors, it is difficult to integrate multiple sensors, and it is difficult to accurately control the working temperature of the array micro-hotplate gas sensors.

[0051] In the process of realizing the concept of the present invention, it is found that by setting the measuring electrode in the first area of ​​the annular structure of the heating electrode and setting the temperature measuring electrode in the second area outside the annular structure of the heating electrode, the miniaturization and integration of the array gas sensor are achieved. And due to the above-mentioned integrated setting, it is helpful to read the working temperature of the heating electrode in time, ensuring the accuracy of temperature measurement and the concentration of heating power. In addition, by determining the substrate as zirconium oxide, it is closer to the thermal expansion coefficient of the gas-sensitive film material and the electrode material, which can improve the situation that the electrode and the gas-sensitive film are easy to fall off. At the same time, since good contact between the electrode and the substrate is achieved, it is also conducive to accurate temperature control.

[0052] Specifically, according to an embodiment of one aspect of the present invention, an array gas sensor is provided. Figure 1a A top view of a gas sensing unit of an array gas sensor according to an embodiment of the present invention is shown; Figure 1b FIG. 4 is a cross-sectional view of a gas sensing unit of an array gas sensor according to an embodiment of the present invention. Figure 1a~Figure 1b As shown, the array gas sensor includes a plurality of gas-sensitive units, which are distributed in an array, and each gas-sensitive unit includes: a zirconia substrate 1, a heating electrode 2, a temperature measuring electrode 5, an insulating layer 6, a measuring electrode 7 and a gas-sensitive film 8. The heating electrode 2 is arranged on the surface of the zirconia substrate 1, and the heating electrode 2 has an unclosed annular structure, and forms a first area 3 inside the annular structure, and forms a second area 4 outside the annular structure; the temperature measuring electrode 5 is arranged on the surface of the zirconia substrate 1 located in the second area 4; the insulating layer 6 covers the surfaces of the heating electrode 2 and the temperature measuring electrode 5 away from the zirconia substrate 1; a plurality of measuring electrodes 7 are arranged on the surface of the insulating layer 6 located in the first area 3 in a toothed distribution; the gas-sensitive film 8 covers the surface of the insulating layer located between the plurality of measuring electrodes 7, and is electrically connected to the measuring electrodes 7.

[0053] It should be noted that Figure 1b The cross-section direction is along Figure 1a A structural diagram of a cross section of the cantilever beam 121 taken from the center of the measuring electrode 7 in a 45° direction.

[0054] According to the embodiment of the present invention, the heating electrode 2 is suitable for providing a heating environment for the gas-sensing unit, and the temperature-measuring electrode 5 is suitable for real-time reading the temperature of the heating electrode 2 in the working state, so as to adjust and control the temperature in the working state. The provision of the insulating layer 6 prevents short circuits between circuits caused by the low resistance of the gas-sensitive material of the gas-sensitive film 8, and prevents unnecessary electrode interference between the heating electrode 2, the temperature-measuring electrode 5, and the measuring electrode 7, further improving the accuracy of temperature control.

[0055] Furthermore, the thermal expansion coefficient of the zirconia substrate 1 in a wide temperature range of 27 to 300° C. is 10.5×10 -6 / K, which is closer to the thermal expansion coefficient of the electrode material and the gas-sensitive film material, further improving the situation where the electrode and the gas-sensitive film are easy to fall off. By dividing the inside and outside of the unclosed annular structure into the first area 3 and the second area 4 respectively, the structure of the array gas sensor is more compact and integrated, and the device structure of the array gas sensor is simplified. By integrating multiple gas-sensitive units into an array gas sensor, it is helpful to detect a single gas or multiple target gases of different concentrations, thereby improving the detection accuracy and broadening the types of gases that can be identified. By arranging the measuring electrode 7 in the first area 3, it is convenient to use the heating electrode 2 to directly heat the gas-sensitive film 8 in the first area 3, and use the measuring electrode 7 to timely capture the resistance change caused by the adsorption of gas molecules by the gas-sensitive film 8. The unclosed annular structure is helpful to heat the gas-sensitive film 8 more evenly. By arranging the temperature measuring electrode 5 in the second area 4, it is helpful to realize real-time monitoring of the working temperature of the heating electrode 2 and improve the accuracy of temperature control.

[0056] The components of each part are integrated on the zirconia substrate 1, so that the entire array gas sensor has a compact structure, which is further conducive to miniaturization and integration, and is applied to a wider range of application fields. The relatively good electrical connection between the gas sensitive film 8 and the measuring electrode 7 helps to ensure the long-term working stability of the array gas sensor.

[0057] It should be noted that if Figure 1a As shown, a certain spacing distance is set between the heating electrode 2 and the temperature measuring electrode 5, and between the temperature measuring electrode 5 and the measuring electrode 7, so as to avoid electrode short circuit caused by errors in overlay accuracy during the electrode preparation process.

[0058] According to an embodiment of the present invention, a zirconium oxide substrate 1 is used as the substrate material, which gives the array gas sensor relatively excellent mechanical strength and thermal stability, enabling it to withstand frequent thermal shocks in the working state and the preparation process, thereby improving the reliability and service life of the device.

[0059] Preferably, please continue to refer to Figure 1a, in the direction parallel to the zirconia substrate 1, the first spacing distance W1 between the temperature measuring electrode 5 and the heating electrode 2, and the second spacing distance W2 between the heating electrode 2 and the measuring electrode 7 are equal. The temperature measuring electrode 5 and the measuring electrode 7 are arranged on both sides of the heating electrode 2, and the spacing distances W1 and W2 are set equal, which helps to ensure that the heat generated by the heating electrode 2 is distributed more evenly in the first area 3 and the second area 4 of the array gas sensor, and improves the consistency of temperature control. Since W1 is equal to W2, the temperature measuring electrode 5 can more accurately reflect the actual temperature near the heating electrode 2, which helps to further improve the accuracy of temperature measurement and ensure the accuracy and reliability of the output signal of the array gas sensor. The first spacing distance W1 and / or the second spacing distance W2 is 5~15μm, for example, it can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm or 15μm, preferably 15μm.

[0060] According to an embodiment of the present invention, the materials of the heating electrode 2 and the temperature measuring electrode 5 include platinum, and the thermal expansion coefficient of platinum in the range of 0 to 100° C. is 9.0×10 -6 / K, the difference in thermal expansion coefficient with the zirconia substrate 1 is small. In the repeated and frequent hot and cold shocks in the working state, the bonding strength between the above-mentioned electrode and the zirconia substrate 1 is stronger, ensuring that the heating electrode 2 and the temperature measuring electrode 5 have good bonding strength with the zirconia substrate 1, and extending the service life. The thickness of the heating electrode 2 and the temperature measuring electrode 5 is 80~120nm, for example, it can be 80nm, 90nm, 100nm, 110nm or 120nm. Preferably, the thickness of the heating electrode 2 and the temperature measuring electrode 5 is 100nm. The thickness of the zirconia substrate 1 is 80~120μm, for example, it can be 80μm, 90μm, 100μm, 110μm or 120μm, preferably 100μm. The material of the insulating layer 6 includes oxide, preferably aluminum oxide, and the insulating layer 6 is provided to reduce the circuit short circuit caused by the low resistance of the gas-sensitive material itself. The thickness of the insulating layer 6 is 30~50nm, for example, it can be 30nm, 40nm or 50nm, preferably 40nm. The material of the measuring electrode 7 includes gold, and the thermal expansion coefficient of gold in the range of 0 to 100°C is 14.2×10 -6 / K, the thermal expansion coefficients of the measuring electrode 7, the heating electrode 2, the temperature measuring electrode 5 and the zirconia substrate 1 are all of the same order of magnitude, and the difference between their thermal expansion coefficients is small, which can reduce the detachment between the electrode and the zirconia substrate 1 in the subsequent working state and the repeated thermal shock of the electrode preparation process. The thickness of the measuring electrode 7 is 80~120nm, for example, it can be 80nm, 90nm, 100nm, 110nm or 120nm, preferably 100nm. The material of the gas sensitive film 8 includes a metal oxide doped with a sensitizing element, and the sensitizing element includes at least one of platinum, gold, indium, and silver. The metal oxide can be tin oxide to enhance the sensitivity to the gas. The line width range of the heating electrode 2, the temperature measuring electrode 5, and the measuring electrode 7 is independently 10~40μm, for example, it can be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm or 40μm, preferably 15~30μm, and more preferably 27μm.

[0061] According to an embodiment of the present invention, there are 16 gas-sensitive units. The present invention can integrate 16 gas-sensitive units on a chip of an array gas sensor by highly integrating and miniaturizing the electrode system. The related art prepares a silicon-based 4-array micro-hotplate gas sensor by utilizing silicon-based surface micromachining technology. Compared with the related art, the present invention realizes the high-precision and high-reliability preparation of 16 units, which helps to promote the further miniaturization, integration and practical application of MEMS gas sensors, and has a broader application prospect.

[0062] According to an embodiment of the present invention, the zirconia substrate 1 has a plurality of through hollows 11, and the surface shape of the hollows 11 can be, for example, a trapezoid or a quasi-trapezoidal shape. To form a bridge structure 12, the bridge structure 12 includes a plurality of cantilever beams 121 and a suspended membrane portion 122 located between the plurality of cantilever beams 121, the cantilever beams 121 provide support for the suspended membrane portion 122; the heating electrode 2, the temperature measuring electrode 5, the insulating layer 6, the measuring electrode 7 and the gas sensitive film 8 are respectively located on the suspended membrane portion 122. The design of the hollows 11 helps to reduce the path of heat conduction, so that the newly generated heat of the heating electrode 2 is more easily concentrated in the area where the gas sensitive film 8 is located, reducing heat loss to other parts of the zirconia substrate 1, improving energy utilization efficiency, and reducing power consumption. The design of the cantilever beams 121 and the suspended membrane portion 122 helps to reduce the thermal stress caused by temperature changes caused by frequent hot and cold shocks, and prolongs the service life of the array gas sensor. Although the suspended design is used, the multiple cantilever beams 121 can provide sufficient support for the suspended membrane portion 122 to avoid mechanical deformation or damage during operation, thereby ensuring the mechanical stability of the array gas sensor. The design of the hollow 11 and the bridge structure 12 helps to achieve the integrity of the complex structure and function in a smaller space, further improving the miniaturization and integration of the entire sensor.

[0063] Furthermore, if Figure 1a As shown, the suspension membrane portion 122 may be, for example, a square, and the side length of the suspension membrane portion may be, for example, 300 μm. The zirconia substrate 1 of each gas sensing unit may be a square, and the side length of the zirconia substrate 1 may be, for example, 1300 μm.

[0064] According to an embodiment of the present invention, the heating electrode 2, the temperature measuring electrode 5 and the measuring electrode 7 are coplanarly arranged, and the heating electrode 2 and the temperature measuring electrode 5 are not in contact with the measuring electrode 7. The coplanar arrangement can be understood as arranging the heating electrode 2, the temperature measuring electrode 5 and the measuring electrode 7 on the same side of the zirconia substrate 1, respectively, and integrating the above three electrodes on the same side of the zirconia substrate 1, which simplifies the device structure, helps to improve production efficiency and reduce manufacturing costs. The coplanar arrangement can reduce interlayer interference between different electrodes, and effectively avoid short circuits, thereby improving the stability and reliability of the array gas sensor. In addition, the coplanar arrangement makes the space occupied by the electrodes more compact, which further contributes to the miniaturization and integration of the array gas sensor.

[0065] It should be noted that, in order to optimize the potential distribution of the heating electrode 2 and the temperature measuring electrode 5 and concentrate the heating power, a layer of gold electrode is added to the peripheral part of the gas sensing unit (not shown in the figure), and the gold electrode is used as a bonding point to connect with the external pin or the pad on the substrate, which is suitable for integrating the array gas sensor with external devices and reducing the circuit resistance of the peripheral part. The thickness of the gold electrode can be 400nm.

[0066] According to another embodiment of the present invention, a method for preparing the array gas sensor as described above is provided. Figure 2 A flow chart of a method for preparing an array gas sensor according to an embodiment of the present invention is shown. Figure 2 As shown, operations S201 to S205 are included.

[0067] In operation S201 , a patterned photoresist mask is formed on a surface of the zirconium oxide substrate 1 .

[0068] According to an embodiment of the present invention, a patterned photoresist mask may be formed by, for example, sequentially applying photoresist, pre-baking, exposing, developing, and post-baking, and the patterned photoresist mask may be applied to subsequent processing steps.

[0069] In operation S202 , a heating electrode 2 and a temperature measuring electrode 5 are formed on the surface of the zirconium oxide substrate 1 by magnetron sputtering under the protection of a photoresist mask.

[0070] According to an embodiment of the present invention, under the protection of the photoresist mask, the patterned area receives the deposition of sputtered material, thereby ensuring that the heating electrode 2 and the temperature measuring electrode 5 are deposited according to a predetermined pattern and size, and the position and shape of the heating electrode 2 and the temperature measuring electrode 5 can be controlled more accurately.

[0071] In operation S203 , an insulating layer 6 and a measuring electrode 7 are sequentially formed on the surfaces of the heating electrode 2 and the temperature measuring electrode 5 away from the zirconia substrate 1 by overlay.

[0072] According to an embodiment of the present invention, overlay can be understood as performing the next photolithography step on the basis of photolithography to ensure that the formed insulating layer 6 and the measuring electrode 7 are precisely aligned with the structure formed in the previous step, thereby achieving higher-precision position matching in the structure of the array gas sensor and improving the sensitivity, selectivity and stability of the array gas sensor.

[0073] In operation S204 , the gas-sensitive slurry is placed in an electrostatic micro-spraying device, and under the action of an electric field, the gas-sensitive slurry is driven to deposit on the surface of the insulating layer 6 between the plurality of measuring electrodes 7 in a stretching manner.

[0074] According to the embodiment of the present invention, electrostatic micro-spraying can be understood as using electric field force to drive liquid to form fine droplets, and depositing the droplets on the surface of the insulating layer 6 between the measuring electrodes 7. By guiding and regulating the deposition position of the gas-sensitive slurry through the electric field force, it is helpful to ensure that the gas-sensitive slurry is deposited between the measuring electrodes 7 (that is, the position of the suspended film portion 122), which helps to make the subsequently formed gas-sensitive film 8 more refined and confined inside the measuring electrodes 7, forming a conductive path, while saving the amount of gas-sensitive slurry and ensuring the stability of the conductive path.

[0075] In operation S205 , the gas-sensitive paste on the surface of the insulating layer 6 is patterned by laser direct writing to form a gas-sensitive film 8 , thereby obtaining an array-type gas sensor.

[0076] According to an embodiment of the present invention, by introducing laser direct writing to photo-cure the gas-sensitive film 8 , fine patterning can be achieved with an accuracy of micrometer or even submicrometer level, which helps to achieve in-situ precise deposition of the gas-sensitive slurry between multiple measuring electrodes 7 .

[0077] According to the embodiment of the present invention, through the process of photolithography and overlay, high-precision patterning of more than 5 μm can be achieved, meeting the high integration and high precision requirements of the electrode structure of the array gas sensor. By introducing electrostatic micro-spraying and laser direct writing, it is helpful to achieve the accuracy of gas-sensitive film slurry deposition, and to obtain a more uniform gas-sensitive film 8, thereby improving the sensitivity and selectivity of the array gas sensor.

[0078] Operation S201 specifically includes: spin coating photoresist on the surface of the zirconia substrate 1, and sequentially performing soft baking, curing, exposure, post-baking, flooding, and development treatments; the temperature of the soft baking is 90-100°C, for example, 90°C, 95°C, or 100°C, and the soft baking time is 180s; the line width range of the exposure is 20-25μm, for example, 20μm, 21μm, 22μm, 23μm, 24μm, or 25μm. Exposure accuracy can help determine the device manufacturing accuracy and the minimum achievable size, and the resolution of the photolithography pattern is a standard for measuring exposure accuracy. The smallest feature size of the extremely small pattern manufactured on the zirconia substrate 1 is regarded as a critical size. By adjusting the designed line width parameters, the minimum achievable critical size can be changed. And by changing the exposure time, it is helpful to achieve the adjustment of the photolithography line width.

[0079] Figure 3 FIG. 2 shows a curve diagram of the exposure time and the photolithography line width of the array gas sensor according to an embodiment of the present invention. Figure 3 As shown, the exposure time is 90 to 200 seconds, for example, it can be 90 seconds, 110 seconds, 130 seconds, 150 seconds, 170 seconds, 190 seconds or 200 seconds. The above-mentioned exposure time setting can realize the regulation of the photolithography line width. If the exposure time is too short, the development process will be affected first. Since the minimum energy value (or minimum exposure amount) of the photoresist required to form a clear pattern is a threshold value, the pattern cannot be correctly developed below this threshold value; in addition, the boundary of the pattern will not be clear enough because the transition between the exposure area and the non-exposure area is too gentle. If the exposure time is too long, the corrosion resistance of the photoresist will be reduced, resulting in jagged edges of the pattern after development, and wrinkles are easily generated on the surface of the film. The present invention helps to accurately control the characteristic dimensions of the three electrodes by optimizing the photolithography process parameters, and realize the miniaturization and high-density integration of the electrode structure.

[0080] According to an embodiment of the present invention, the intensity of the electric field is 0.5~2.5kV, for example, it can be 0.5kV, 1kV, 1.5kV, 2kV or 2.5kV, preferably 1~2kV. Adjusting the electric field intensity within the above range is conducive to driving the gas-sensitive slurry to be deposited more evenly on the surface of the insulating layer 6. The power of laser direct writing is 0.1~1W, for example, it can be 0.1W, 0.2W, 0.3W, 0.4W, 0.5W, 0.6W, 0.7W, 0.8W, 0.9W or 1W. The power of laser direct writing directly determines the intensity of the laser beam during the laser direct writing process, and ultimately determines the cured size of the gas-sensitive film layer.

[0081] Figure 4The optical micrographs of the cured line width and morphology of the gas-sensitive slurry under different laser powers are shown in the embodiment of the present invention, wherein a is an optical micrograph at 0.05W power, b is an optical micrograph at 0.1W power, c is an optical micrograph at 0.15W power, d is an optical micrograph at 0.3W power, e is an optical micrograph at 0.45W power, f is an optical micrograph at 0.6W power, g is an optical micrograph at 0.75W power, and h is an optical micrograph at 0.9W power. Figure 4 As shown, it can be seen that when the power is too small, the gas-sensitive slurry is difficult to solidify; when the power of laser direct writing is too large, it will cause overexposure when the laser beam scans the photocuring gas-sensitive slurry, making the laser direct writing line thicker and failing to achieve the highest dimensional accuracy of laser direct writing.

[0082] Preferably, the line width of the laser can be 20μm, the laser pulse frequency scanning speed is set to 1000mm / s, the number of scans is 100 times, the laser focal length is 46.71mm, and the laser power adjustment range at 1000ns is 0.15~0.90W, for example, it can be 0.15W, 0.30W, 0.45W, 0.60W, 0.75W and 0.90W.

[0083] According to an embodiment of the present invention, after operation S203, the process further includes: performing hollow etching on the zirconium oxide substrate 1 by laser, wherein during the hollow etching, the galvanometer light emission distance is 12.1-14.4 mm, for example, 12.1 mm, 12.6 mm, 13.1 mm, 13.6 mm or 14.4 mm. There is a certain gap between the actual via diameter of the laser etching and the set value, which is mainly caused by the line width factor of the laser itself.

[0084] Figure 5 A curve diagram showing the laser etching light emission distance and the aperture size of the array gas sensor of the embodiment of the present invention is shown. In the process of carrying out the relevant embodiments of the present invention, it was found that there is a linear correlation between the laser etching light emission distance and the aperture size, and the aperture size can be reasonably designed based on this relationship so as to accurately process the ideal micropore size. The aperture size can be regulated by the light emission distance, and the selection range of the light emission distance is: 12.1-14.4mm. Within the above light emission distance selection range, the corresponding light emission aperture size can be determined to be 20~60μm. The galvanometer light emission distance can be understood as the distance from the laser galvanometer to the zirconia substrate 1. The introduction of laser etching improves the flexibility and accuracy of the hollowing processing of the zirconia substrate 1.

[0085] According to an embodiment of the present invention, the gas-sensitive slurry includes a photocuring agent, a cross-linking agent, a leveling agent, a metal oxide powder doped with a sensitizing element, and an organic solution; the photocuring agent includes polyurethane acrylate, the cross-linking agent includes at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; the leveling agent includes phosphate-modified acrylate. In the experiments related to the present invention, it was found that when the above-mentioned gas-sensitive slurry is used, electrostatic micro-spraying and laser direct writing can be used together, and the micro-spraying hole blocking phenomenon can be avoided during the electrostatic micro-spraying process, and the laser direct writing can be cured and formed relatively quickly. By curing the gas-sensitive slurry into a gas-sensitive film 8, it is helpful to apply the 16-unit array gas sensor to gas sensing detection.

[0086] According to an embodiment of the present invention, before operation S201 , the method further includes: ultrasonically cleaning the zirconia substrate 1 to ensure the cleanliness of the surface of the zirconia substrate 1 .

[0087] Figure 6 The preparation flow chart of the array gas sensor of the embodiment of the present invention is shown. Figure 6 The figure shows a specific description of the preparation process of a 16-unit array gas sensor.

[0088] A polished ZrO2 substrate is selected and ultrasonically cleaned three times with acetone, alcohol and water respectively. After cleaning, a photoresist is spin-coated, for example, Az-5214 reverse glue can be selected. After spin coating, the ZrO2 substrate is soft-baked and cured, and then scanned and exposed using a concentrated linear ultraviolet light. After exposure, the ZrO2 substrate is post-baked, flood-exposed and developed, and then placed in a plasma cleaner for further cleaning.

[0089] After cleaning, a metal electrode layer is plated on the substrate by magnetron sputtering. After the electrode coating is completed, the ZrO2 substrate is placed in an acetone water bath and heated, and ultrasonic treatment is used to remove the photoresist. This completes the photolithography of a layer of electrode. By merging the electrodes in the low potential area of ​​the circuit, the frequency of use of the electrode pins is increased. In the subsequent manufacturing process, the insulating layer 6, the heating electrode 2, the temperature measuring electrode 5 and the measuring electrode 7 are overlaid three times, and each step requires strict position calibration. The process of three overlays is basically the same as that of the first layer of electrodes, which will not be repeated here.

[0090] Different gas-sensitive slurries were sprayed on the 16-unit array by micro-spraying-photocuring technology to complete the manufacture of 16-unit gas-sensitive chips. Glass needles with inner diameters of 40μm and 100μm were used for micro-spraying to form circular spray patterns with radii of 75μm and 150μm, respectively. A laser was used to perform trapezoidal hollow etching around the ZrO2 substrate. The distance from the laser galvanometer to the ceramic substrate was defined as the light-emitting distance, and the line width of a single straight line processed at this distance was used as a standard for evaluating the laser etching power density. The smaller the line width, the greater the power density. In order to adjust the light-emitting distance, the height of the sample table can be changed, with the spacing adjusted by 0.02mm each time, from the starting height of 12.1mm to 14.4mm.

[0091] The laser pulse frequency scanning speed was set to 1000 mm / s, the number of scans was 100, the laser focal length was 46.7 mm, and the laser power at 1000 ns ranged from 0.15 to 0.90 W. After laser direct writing, the linear light-cured gas-sensitive film 8 was obtained under different laser powers by dissolving and removing the glue.

[0092] It should be noted that the hollowing can be performed before or after spraying the gas-sensitive slurry, and is not particularly limited in the present invention.

[0093] The present invention is further described below by examples, drawings and related test experiments and results thereof. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, it is obvious that one or more embodiments may also be implemented without these specific details. And, in the absence of conflict, the details in the following embodiments may be combined arbitrarily into other feasible embodiments.

[0094] It should be noted that the following specific examples are only for illustration, and the protection scope of the present invention is not limited thereto. The chemicals and raw materials used in the following examples are all commercially available or homemade by recognized processing methods.

[0095] Embodiment 1:

[0096] Substrate cleaning: A polished ZrO2 ceramic substrate with a thickness of 100 μm was selected and ultrasonically cleaned in acetone, alcohol and deionized water for 10 minutes, followed by plasma cleaning for 5 minutes.

[0097] Spin coating exposure: Spin the photoresist at a speed of 3000r / min. After spin coating, the device is soft-baked to harden the film. According to the parameters of 100s of coating, soft baking: hot plate 95℃, 180s, exposure time: 200s, reverse baking: hot plate 100℃, 90s, development 90s; hardening: hot plate 110℃, 180s, the patterns of temperature measuring electrode and heating electrode, insulating layer and measuring electrode are obtained. Use beam linear ultraviolet light to scan and expose at a speed of 0.1mm / s. After flood exposure and development, put it into a plasma cleaner for cleaning.

[0098] Preparation of Pt heating electrode and Pt temperature measuring electrode: Use DC magnetron sputtering to form Pt with a thickness of 100 nm on the surface of the cleaned substrate. After taking it out, heat it to 40°C in an acetone water bath and ultrasonically peel off the film for 10 minutes. Clean the photoresist at the reverse pattern position to leave the required Pt electrode layer.

[0099] Preparation of Al2O3 insulating layer: RF magnetron sputtering is used to form an Al2O3 film with a thickness of 40nm on the surface of the substrate. After taking it out, it is heated to 40℃ in an acetone water bath and ultrasonically removed for 10 minutes to remove the film. The photoresist at the reverse pattern position is cleaned off, leaving the required Al2O3 insulating layer. Annealing at 500℃ for 2 hours to form a smoother and denser Al2O3 insulating layer.

[0100] Preparation of Au measuring electrode: Au with a thickness of 100 nm was formed on the surface of the Al2O3 insulating layer by DC magnetron sputtering. After taking it out, it was heated to 40°C in an acetone water bath and ultrasonically peeled off for 10 minutes to clean the photoresist at the reverse pattern position, leaving the required Au measuring electrode.

[0101] Substrate hollowing: After completing the above four photolithography processes, the galvanometer light output distance is set to 12.10 mm, and the substrate is laser hollowed out with a specific pattern to reduce the heat conduction of the device and reduce the power consumption of the device.

[0102] Preparation of gas-sensitive slurry: 30g polyurethane acrylate (PUA), 5g 1,6-hexanediol diacrylate (HDDA), 5g trimethylolpropane triacrylate (TMPTA) and 0.16g leveling agent phosphate-modified acrylate (BYK-354) were added to a 100mL beaker and magnetically stirred for 2h to obtain a photosensitive resin premix, 9g of the photosensitive resin premix, 6g Sr / SnO2 gas-sensitive material powder and 15mL of isopropanol were added to a ball mill, and ball milled at 350r / min for 4h. 0.47g of photoinitiator 184 was placed in 4mL of isopropanol for ultrasonic dispersion and added to the ball mill, and continued to ball mill at 350r / min for 1h to obtain a light-cured gas-sensitive slurry.

[0103] Integration of gas-sensitive layer: Place the photocurable gas-sensitive slurry into the syringe in the electrostatic micro-spraying device. The diameter of the syringe needle is 100μm. Place the micro-hotplate chip on the adsorption platform. Align the needle to the center of a single gas-sensitive unit. Apply air pressure to electrostatically spray the photocurable gas-sensitive slurry. The adsorption platform automatically moves to the center of the next gas-sensitive unit for electrostatic spraying. A total of 16 gas-sensitive units are electrostatically sprayed. After drying to remove the solvent in the photocurable gas-sensitive slurry on the micro-hotplate chip, read the laser direct writing pattern. The pattern is 16 100μm circles. Laser direct writing is performed with a laser power of 0.15W. Place the micro-hotplate chip in anhydrous ethanol and deionized water to dissolve and remove the glue to obtain a single-layer photocurable gas-sensitive slurry film. After sintering at 350℃ for 24h and removing the organic matter, 16 single-layer gas-sensitive films are obtained, and a 16-unit array gas sensor 1 is obtained.

[0104] Embodiment 2:

[0105] The process of this embodiment 2 is substantially the same as that of embodiment 1, except that the exposure time in the spin coating exposure is adjusted to 180 s, the galvanometer light output distance when the substrate is hollowed out is set to 12.6 mm, the gas-sensitive material powder in the gas-sensitive slurry is adjusted to 6 gRu / SnO2, and the laser power in the gas-sensitive layer integration is adjusted to 0.30 W, thereby preparing a 16-unit array gas sensor 2.

[0106] Embodiment 3:

[0107] The process of this embodiment 3 is substantially the same as that of embodiment 1, except that the exposure time in the spin coating exposure is adjusted to 150 s, the galvanometer light output distance when the substrate is hollowed out is set to 13.1 mm, the gas-sensitive material powder in the gas-sensitive slurry is adjusted to 6 g Pd / SnO2, and the laser power in the gas-sensitive layer integration is adjusted to 0.45 W, thereby preparing a 16-unit array gas sensor 3.

[0108] Embodiment 4:

[0109] The process of this embodiment 4 is substantially the same as that of embodiment 1, except that the exposure time in the spin coating exposure is adjusted to 100 s, the galvanometer light output distance when the substrate is hollowed out is set to 13.6 mm, the gas-sensitive material powder in the gas-sensitive slurry is adjusted to 6 gRh / SnO2, and the laser power in the gas-sensitive layer integration is adjusted to 0.75 W, thereby preparing a 16-unit array gas sensor 4.

[0110] Embodiment 5:

[0111] The process of this embodiment 5 is substantially the same as that of embodiment 1, except that the exposure time in the spin coating exposure is adjusted to 90 s, the galvanometer light output distance when the substrate is hollowed out is set to 14.4 mm, the gas-sensitive material powder in the gas-sensitive slurry is adjusted to 6 gCd / SnO2, and the laser power in the gas-sensitive layer integration is adjusted to 0.90 W, thereby preparing a 16-unit array gas sensor 5.

[0112] Figure 7 The cross-sectional micrographs of the photocuring of the gas-sensitive film of the gas-sensitive unit of Examples 1 to 5 of the present invention at 10 μm are shown, wherein a is the cross-sectional micrograph of Example 1, b is the cross-sectional micrograph of Example 2, c is the cross-sectional micrograph of Example 3, d is the cross-sectional micrograph of Example 4, and e is the cross-sectional micrograph of Example 5. Figure 7 As shown in a~e in the figure, it can be seen that Examples 1~5 can prepare dense and uniform electrode layers and gas-sensitive layers, and the electrode layer and the gas-sensitive layer can fit tightly, which is helpful for subsequent applications in gas-sensitive response.

[0113] Figure 8 The figure shows the response time curve of each unit of the 16-unit Sr / SnO2 gas sensor array of Example 1 of the present invention to 100 ppm ethanol at 400°C. Figure 8 As shown, it can be seen that at an ethanol concentration of 100 ppm, the overlap between the first unit to the sixteenth unit is relatively good, indicating that each gas-sensitive unit has good consistency.

[0114] Fig. 9 The figure shows the response of each unit of the 16-unit Sr / SnO2 array gas sensor of Example 1 of the present invention to 0.1ppm, 1ppm, 10ppm, 50ppm and 100ppm ethanol concentrations at 400°C. Fig. 9 As shown, it means that under different concentrations of ethanol, the first to sixteenth units still have good response consistency, and still have good response when the ethanol concentration is low, indicating that the 16-unit Sr / SnO2 array gas sensor has higher sensitivity to lower concentrations of ethanol.

[0115] Fig.10a The pulse curves of the array gas sensors prepared in Examples 2 to 5 of the present invention at 200 to 400°C over time are shown. Fig.10a As shown, it means that between 200~400℃, the performance of sensor chips made of different gas-sensitive materials does not decay or change under different heating temperatures, indicating that the chip has a strong tolerance to thermal shock. Fig.10bThe response and recovery curves of the array gas sensors prepared in Examples 2 to 5 of the present invention to 500 ppb ethanol concentration under pulse temperature modulation of 200 to 400°C are shown. Fig.10b As shown, S=R gas / R air In, R air It can be understood as the resistance of air entering the gas sensor, R gas It can be understood as the resistance of the target gas passing into the gas sensor, and the sensitivity calculation formula R gas / R air The sensitivity value to the target gas is obtained. It shows that different gas-sensitive materials have different responses to ethanol gas. For 500ppb ethanol, the response change of Cd / SnO2 to ethanol is the highest, and its response change is 0.34.

[0116] It can be understood that the present invention adopts a zirconium oxide substrate, combined with multiple processes such as photolithography, magnetron sputtering, laser etching and electrostatic micro-spraying, to achieve the manufacture of high-precision, high-reliability, and multifunctional array gas sensors. By optimizing process parameters, such as exposure time and line width design in photolithography, light output distance in laser etching, and laser power in micro-spray-photocuring, it helps to accurately control the electrode characteristic size, micropore diameter and gas-sensitive film curing size, obtain a uniform and dense gas-sensitive film, improve the sensitivity and selectivity of the device, and meet the high integration and high precision requirements of the electrode structure of the micro gas sensor. In addition, the present invention adopts a coplanar stacked electrode design, which simplifies the device structure and reduces the manufacturing cost. The reasonable electrode layout ensures the accuracy of temperature measurement and the concentration of heating power. And through an array-type integrated manufacturing method, a variety of gas-sensitive materials are integrated on a single chip, and the preparation of a 16-unit gas-sensitive array is realized, which expands the versatility and application range of the device. The present invention optimizes the process parameters, including the exposure time (90-200s) and line width parameters in photolithography, the light emission distance (12.1-14.4mm) in laser etching, and the laser power (0.15-0.90W) in micro-spray-photocuring, to achieve precise control of the electrode characteristic size, micropore diameter and gas-sensitive film curing size. The present invention realizes the preparation of high-performance and multifunctional array gas sensors, and provides an innovative technical path for promoting the miniaturization, integration and practical application of array gas sensors.

[0117] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An array gas sensor, characterized in that: The invention comprises a plurality of gas sensing units, which are distributed in an array, and each of the gas sensing units comprises: Zirconia substrate; A heating electrode is arranged on the surface of the zirconia substrate, wherein the heating electrode has an unclosed annular structure, and a first area is formed inside the annular structure, and a second area is formed outside the annular structure; A temperature measuring electrode, the temperature measuring electrode is arranged on the surface of the zirconia substrate located in the second area; An insulating layer, covering the surfaces of the heating electrode and the temperature measuring electrode away from the zirconia substrate; A plurality of measuring electrodes are arranged in a tooth-shaped distribution on the surface of the insulating layer located in the first area; A gas-sensitive film, covering the surface of the insulating layer between the plurality of measuring electrodes and electrically connected to the measuring electrodes; In a direction parallel to the zirconia substrate, a first spacing distance between the temperature measuring electrode and the heating electrode is equal to a second spacing distance between the heating electrode and the measuring electrode; The first spacing distance and / or the second spacing distance is 5-15 μm.

2. The array gas sensor according to claim 1, characterized in that: The material of the heating electrode and the temperature measuring electrode includes platinum, and the thickness of the heating electrode and the temperature measuring electrode is 80-120 nm; The thickness of the zirconia substrate is 80-120 μm; The material of the insulating layer includes oxide, and the thickness of the insulating layer is 30-50 nm; The material of the measuring electrode includes gold, and the thickness of the measuring electrode is 80-120 nm; The material of the gas-sensitive film includes a metal oxide doped with a sensitizing element, wherein the sensitizing element includes at least one of platinum, gold, indium, and silver; The line width ranges of the heating electrode, the temperature measuring electrode, and the measuring electrode are independently 10 to 40 μm.

3. The array gas sensor according to claim 1, characterized in that: The number of the gas sensing units is 16.

4. The array gas sensor according to claim 1, characterized in that: The zirconia substrate has a plurality of through hollows to form a bridge structure, wherein the bridge structure includes a plurality of cantilever beams and a suspended membrane portion located between the plurality of cantilever beams, and the cantilever beams provide support for the suspended membrane portion; Wherein, the heating electrode, the temperature measuring electrode, the insulating layer, the measuring electrode and the gas sensitive film are respectively located on the suspended film part.

5. The array gas sensor according to claim 1, characterized in that: The heating electrode and the temperature measuring electrode are arranged on the same plane as the measuring electrode, and the heating electrode and the temperature measuring electrode are not in contact with the measuring electrode.

6. A method for preparing an array gas sensor as claimed in any one of claims 1 to 5, characterized in that: The preparation method comprises: forming a patterned photoresist mask on a surface of a zirconium oxide substrate; Under the protection of the photoresist mask, a heating electrode and a temperature measuring electrode are formed on the surface of the zirconium oxide substrate by magnetron sputtering; By overlaying, an insulating layer and a measuring electrode are sequentially formed on the surfaces of the heating electrode and the temperature measuring electrode away from the zirconium oxide substrate; The gas-sensitive slurry is placed in an electrostatic micro-spraying device, and under the action of an electric field, the gas-sensitive slurry is driven to deposit on the surface of the insulating layer between the plurality of measuring electrodes in a stretching manner; The gas-sensitive slurry on the surface of the insulating layer is patterned by laser direct writing to form a gas-sensitive film, thereby obtaining the array-type gas sensor.

7. The preparation method according to claim 6, characterized in that: The intensity of the electric field is 0.5~2.5kV, and the power of the laser direct writing is 0.1~1W; Forming the patterned photoresist mask on the surface of the zirconium oxide substrate comprises: Spin-coat a photoresist on the surface of a zirconium oxide substrate, and sequentially perform soft baking, curing, exposure, post-baking, flood exposure, and development processes; The soft baking temperature is 90-100°C and the soft baking time is 180s; The exposure time is 90 to 200 seconds.

8. The preparation method according to claim 6, characterized in that: After the insulating layer and the measuring electrode are sequentially formed on the surfaces of the heating electrode and the temperature measuring electrode away from the zirconium oxide substrate, the method further comprises: The zirconium oxide substrate is hollowed out and etched by laser, wherein during the hollowing out and etching, the galvanometer light emission distance is 12.1-14.4 mm.

9. The preparation method according to claim 6, characterized in that: The gas-sensitive slurry comprises a photocuring agent, a cross-linking agent, a leveling agent, a metal oxide powder doped with a sensitizing element, and an organic solution; The photocuring agent includes polyurethane acrylate, the crosslinking agent includes at least one of 1,6-hexanediol diacrylate and trimethylolpropane triacrylate; and the leveling agent includes phosphate-modified acrylate.

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