A differential decoupling double-spiral gas-sensitive gap sensor element and a preparation method thereof

Abstract

The application discloses a differential decoupling double-spiral gas-sensitive gap sensing element and a preparation method thereof, and belongs to the technical field of sensors. The differential decoupling double-spiral gas-sensitive gap sensing element comprises a substrate, a lower layer gas-sensitive material spiral film, a lower layer insulating film, a center electrode, a middle layer gas-sensitive material wire film, an upper layer insulating film and an upper layer gas-sensitive material spiral film. The upper layer gas-sensitive material spiral film is exposed to the environment, and a change in a gas atmosphere will cause a change in the conductivity of the upper layer gas-sensitive material spiral film. The lower layer gas-sensitive material spiral film is completely covered by the lower layer insulating film and will not change. A differential structure formed by the center electrode and the middle layer gas-sensitive material wire film can decouple the gas signal and calculate the gap signal. The differential decoupling double-spiral gas-sensitive gap sensing element can be used for simultaneous measurement of gas and gap, and is suitable for fields such as electronic skin or complex instrument narrow and small curved surface interval parameter measurement.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology, and specifically relates to the fabrication of a gap gas sensor. Background Technology

[0002] With the advent of Industry 4.0, global economic and technological levels are rapidly developing, but the accompanying environmental problems are becoming increasingly severe. Humanity is focusing more and more on environmental and health issues upon which survival depends. Air is essential for the survival of most living organisms. Air pollution can lead to stroke, heart disease, lung cancer, chronic obstructive pulmonary disease (COPD), and respiratory infections, including pneumonia. According to the latest estimates from the World Health Organization (WHO), 7 million people die from air pollution each year. In the chemical industry and biopharmaceuticals, monitoring flammable, explosive, toxic, and harmful gases is a prerequisite for ensuring production and personnel safety. In the food industry and agricultural production, monitoring volatile organic compounds (VOCs) is crucial for food safety. In traffic safety and daily life, monitoring combustible gases is essential for ensuring social safety and the safety of people and property. Furthermore, in disease diagnosis, monitoring VOCs exhaled or exhaled by humans can enable early disease prediction and diagnosis. Therefore, research on high-performance gas sensors has attracted significant attention.

[0003] With the advent of Microelectromechanical Systems (MEMS), the demand for sensor integration is increasing. Integrating sensors with different functions and sensitivity directions, and exploring new principles and functions through miniaturization and integration, leads to components and systems that elevate automation, intelligence, and reliability to a new level, significantly impacting industry, agriculture, information technology, environment, bioengineering, medicine, space technology, and scientific development. The limited space between curved surfaces in large equipment makes it unsuitable to install multiple sensors for monitoring parameters such as ambient gases, gap changes, amplitude changes, and workpiece wear. Therefore, research on using a single sensor element to achieve multi-parameter measurement has attracted considerable attention. Summary of the Invention

[0004] The purpose of this invention is to realize multi-parameter measurement and signal decoupling of sensors, and to obtain relevant parameters in a limited installation environment. This invention proposes a differential decoupled dual-helix gas-sensitive gap sensing element and its manufacturing method.

[0005] The differentially decoupled dual-helix gas-sensitive gap sensing element of this invention includes a substrate, a lower gas-sensitive material spiral film, a lower insulating film, a lower central electrode, a middle gas-sensitive material wire film, an upper insulating film, an upper central electrode, and an upper gas-sensitive material spiral film. The upper gas-sensitive material spiral film is exposed to the environment; changes in the gas atmosphere cause changes in its conductivity. The lower gas-sensitive material spiral film, completely covered by the lower insulating film, remains unchanged. The differential structure formed by the central electrode and the middle gas-sensitive material film wires allows for decoupling of the gas signal and calculation of the gap signal. This differentially decoupled dual-helix gas-sensitive gap sensing element can be used for simultaneous measurement of gas and gap, and is suitable for applications such as parameter measurement between narrow curved surfaces in electronic skin or complex instruments.

[0006] The technical solution of the method for developing a differentially decoupled dual-helix gas-sensitive gap sensing element proposed in this invention is as follows:

[0007] Step (1) Cleaning of substrate and mask: Ultrasonically clean the substrate and the first spiral mask, the second spiral mask, the first insulating mask, the second insulating mask, the center electrode mask, and the wire mask for 20 minutes each in acetone, anhydrous ethanol, and deionized water respectively; dry them with nitrogen and place them in a fume hood for later use.

[0008] Step (2) Preparation of the lower gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first spiral mask is covered on the substrate described in step (1) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the substrate, which is the lower gas-sensitive material spiral film.

[0009] Step (3) Preparation of the lower insulating film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first insulating mask is used to cover the sample prepared in step (2) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the insulating material. Finally, the insulating film is prepared on the sample in step (2), which is the lower insulating film.

[0010] Step (4) Preparation of the lower center electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, a center electrode mask is used to cover the sample prepared in step (3) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material center electrode is prepared on the sample in step (3), which is the lower center electrode. The thickness of the lower center electrode is consistent with the thickness of the insulating film in step (2).

[0011] Step (5) Preparation of the middle layer gas-sensitive material wire film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, cover the sample prepared in step (4) with the wire mask and place it at the sample deposition position of the vapor deposition equipment. Turn on the vacuum acquisition device to obtain the background vacuum required by the process, introduce the process gas, adjust the gate valve of the vacuum acquisition device to control the working pressure required during deposition, turn on the power source, and after the pre-deposition is completed, open the baffle to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material wire film is prepared on the sample in step (4), which is the middle layer gas-sensitive material wire film.

[0012] Step (6) Preparation of the upper insulating film: Using vapor deposition technology and raw materials for preparing insulating materials with a purity of 99.99% or higher, a second insulating mask is used to cover the sample prepared in step (5) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the gate valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of the insulating material. Finally, the insulating film prepared on the sample in step (5) is the upper insulating film.

[0013] Step (7) Preparation of the upper central electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, a central electrode mask is used to cover the sample prepared in step (6) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required for deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material central electrode is prepared on the sample in step (6), which is the upper central electrode. The thickness of the upper central electrode is consistent with the thickness of the insulating film in step (6).

[0014] Step (8) Preparation of the upper gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the second spiral mask is placed on the sample prepared in step (7) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the gate valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the sample in step (7), which is the upper gas-sensitive material spiral film, and the differential decoupled double spiral gas-sensitive gap sensing element is obtained.

[0015] The working mode and principle of the differential decoupled dual-helix gas-sensitive gap sensing element developed using the method proposed in this invention are explained below:

[0016] When an alternating current is applied to the electrodes of the upper and lower gas-sensitive material spiral films of the sensing element, both layers of gas-sensitive material spiral films generate magnetic fields. Since the spirals rotate in the same direction and their centers coincide, the magnetic fields generated by the two layers are superimposed, increasing the magnetic field strength and thus enhancing the gap-sensing effect of the sensing element. The upper gas-sensitive material spiral film is exposed; when it is in an oxidizing or reducing gas environment, the oxygen molecules adsorbed by the gas-sensitive material undergo an oxidation-reduction reaction with the gas molecules, altering parameters such as the conductivity of the gas-sensitive material, thereby exhibiting a gas-sensing effect. The voltage across the upper and lower gas-sensitive material spiral films is obtained using a measuring device, and the voltage difference is obtained using a differential method. Based on the "gas concentration-voltage difference" calibration relationship of the sensing element, the concentration signal of the measured gas can be obtained. The gap signal can be obtained by combining the voltage across the lower gas-sensitive material spiral film with the "gap-voltage" calibration relationship of the sensing element.

[0017] Features and effects of the present invention:

[0018] 1. The sensing element prepared by the present invention includes two spirals with the same rotation direction, forming a differential structure through a central conductor. The upper gas-sensitive material spiral film is exposed to the atmosphere and has gas-sensitive effect and gap-sensitive effect, while the lower gas-sensitive material spiral film is covered by an insulating layer and only has a gap-sensitive effect. With the help of relevant measurement equipment and data processing methods, the gas-sensitive signal and the gap-sensitive signal can be decoupled.

[0019] 2. The sensing element developed in this invention has two helices. When alternating current is applied, a superimposed magnetic field is formed. The magnetic field strength is enhanced, and the eddy current effect is enhanced accordingly, which enhances the gap sensitivity effect.

[0020] 3. The sensing element developed in this invention is composed entirely of gas-sensitive materials and insulating materials, without the introduction of metal electrodes, thus avoiding the electromagnetic influence of metal wires. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a differentially decoupled double-helix gas-sensitive gap sensing element.

[0022] Figure 2 This is a schematic diagram of the fabrication of the spiral thin film of the lower gas-sensitive material.

[0023] Figure 3 This is a schematic diagram of the lower insulating film preparation process.

[0024] Figure 4 This is a schematic diagram of the fabrication of the lower layer center electrode.

[0025] Figure 5 This is a schematic diagram of the fabrication of a thin film for a mid-layer gas-sensitive material conductor.

[0026] Figure 6 This is a schematic diagram of the upper insulating film preparation process.

[0027] Figure 7 This is a schematic diagram of the fabrication of the upper central electrode.

[0028] Figure 8 This is a schematic diagram of the fabrication of the spiral thin film of the upper gas-sensitive material.

[0029] In the attached diagram, the components represented by each number are as follows: a) upper gas-sensitive material spiral film; b) upper insulating film; c) upper center electrode; d) middle gas-sensitive material conductive film; e) lower center electrode; f) lower insulating film; g) lower gas-sensitive material spiral film; h) substrate; 1) first spiral mask; 2) second spiral mask; 3) first insulating mask; 4) second insulating mask; 5) center electrode mask; 6) conductive film mask. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] A schematic diagram of a differentially decoupled dual-helix gas-sensitive gap sensing element is shown below. Figure 1 As shown, its preparation method includes the following eight steps:

[0032] Step (1) Cleaning of substrate and mask: Ultrasonically clean the substrate and the first spiral mask, the second spiral mask, the first insulating mask, the second insulating mask, the center electrode mask, and the wire mask for 20 minutes each in acetone, anhydrous ethanol, and deionized water respectively; dry them with nitrogen and place them in a fume hood for later use.

[0033] Step (2) Preparation of the lower gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first spiral mask is covered on the substrate described in step (1) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the substrate, which is the lower gas-sensitive material spiral film.

[0034] Step (3) Preparation of the lower insulating film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first insulating mask is used to cover the sample prepared in step (2) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the insulating material. Finally, the insulating film is prepared on the sample in step (2), which is the lower insulating film.

[0035] Step (4) Preparation of the lower center electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, a center electrode mask is used to cover the sample prepared in step (3) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material center electrode is prepared on the sample in step (3), which is the lower center electrode. The thickness of the lower center electrode is consistent with the thickness of the insulating film in step (2).

[0036] Step (5) Preparation of the middle layer gas-sensitive material wire film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, cover the sample prepared in step (4) with the wire mask and place it at the sample deposition position of the vapor deposition equipment. Turn on the vacuum acquisition device to obtain the background vacuum required by the process, introduce the process gas, adjust the gate valve of the vacuum acquisition device to control the working pressure required during deposition, turn on the power source, and after the pre-deposition is completed, open the baffle to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material wire film is prepared on the sample in step (4), which is the middle layer gas-sensitive material wire film.

[0037] Step (6) Preparation of the upper insulating film: Using vapor deposition technology and raw materials for preparing insulating materials with a purity of 99.99% or higher, a second insulating mask is used to cover the sample prepared in step (5) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the gate valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of the insulating material. Finally, the insulating film prepared on the sample in step (5) is the upper insulating film.

[0038] Step (7) Preparation of the upper central electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, a central electrode mask is used to cover the sample prepared in step (6) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required for deposition, the power source is turned on, and after the pre-deposition is completed, the baffle is turned on to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material central electrode is prepared on the sample in step (6), which is the upper central electrode. The thickness of the upper central electrode is consistent with the thickness of the insulating film in step (6).

[0039] Step (8) Preparation of the upper gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the second spiral mask is placed on the sample prepared in step (7) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the gate valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the sample in step (7), which is the upper gas-sensitive material spiral film, and the differential decoupled double spiral gas-sensitive gap sensing element is obtained.

[0040] Example – Physical Vapor Deposition – Magnetron Sputtering Technology

[0041] The fabrication of a differentially decoupled twin-helix gas-sensitive gap sensing element includes the following eight steps:

[0042] Step (1) Cleaning of ceramic substrate and mask: The ceramic substrate h and the first spiral mask 1, second spiral mask 2, first insulating mask 3, second insulating mask 4, center electrode mask 5, and wire mask 6 were ultrasonically cleaned for 20 minutes each in acetone, anhydrous ethanol, and deionized water, respectively. They were then dried with nitrogen and placed in a fume hood for later use. The acetone and anhydrous ethanol used were AR (Analytical Reagent) grade and were not further purified. The dimensions of the first spiral mask 1 were 50mm × 38.5mm × 0.01mm, with a line width and spacing of 0.5mm, 10 turns, a center inner diameter of φ4mm, a spiral lead wire width of 1mm, and a circular terminal diameter of φ4mm. Figure 2 As shown; the first insulating mask 3 used consists of a rectangular mask with a diameter of 10mm × 12.8mm × 0.01mm and a circular mask with a diameter of φ4mm × 0.01mm, as shown. Figure 3 As shown; the dimensions of the center electrode mask 5 used are 50mm × 38.5mm × 0.01mm, and it has a circular hole with a diameter of φ4mm. The center of the circular hole coincides with the center of the inner diameter of the first helical mask 1, as shown. Figure 4 As shown; the dimensions of the center electrode mask 5 used are 50mm × 38.5mm × 0.01mm. It has two circular holes with a diameter of φ4mm, and the distance between the centers of the two holes is 25.75mm. One of the holes coincides with the center of the inner diameter of the first helical mask 1. The two holes are connected by a 1mm wide gap, as shown. Figure 5 As shown; the second insulating mask 4 used consists of a rectangular mask with a diameter of 10mm × 25.6mm × 0.01mm and a circular mask with a diameter of φ4mm × 0.01mm, as shown. Figure 6 As shown; the dimensions of the second helical mask 2 used are 50mm × 38.5mm × 0.01mm, with a line width and spacing of 0.5mm, 10 turns, a center inner diameter of φ4mm, a helical lead wire width of 1mm, and a circular terminal diameter of φ4mm. Its helical rotation direction is opposite to that of the first helical mask 1, which can be considered as the helical mask 1 being rotated 180° along its long centerline. To prevent contact contamination, the first helical mask 1 cannot be used in reverse. Therefore, the first helical mask 1 and the second helical mask 2 are considered as two independent masks, as shown... Figure 8 As shown;

[0043] Step (2) Preparation of the lower gas-sensitive material spiral film, as shown in the schematic diagram. Figure 2 As shown: Magnetron sputtering, a physical vapor deposition technique, and a 99.99% pure Sn metal target are used as raw materials for preparing the n-type gas-sensitive material SnO2. A first spiral mask 1 is placed on the ceramic substrate h described in step (1) and positioned on the sample stage of the magnetron sputtering equipment. The stage rotation speed is set to 10 r / min. The vacuum acquisition device is turned on, and the vacuum level is maintained at 8 × 10⁻⁶. -4 At Pa, the gas-sensitive material SnO2 was prepared by reactive sputtering. Argon gas at 45 sccm and oxygen gas at 1.2 sccm were introduced, both with a purity of 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure stabilized at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 25 W. When the power was stable, the sputtering voltage was about 380 V and the sputtering current was about 66 mA. After pre-sputtering for 1 hour, the baffle was turned on and sputtering was performed for 20 minutes. After sputtering was completed, the equipment was turned off and the sample was taken out. At this time, a gas-sensitive material SnO2 spiral film was prepared on the ceramic substrate h, which is the lower gas-sensitive material spiral film g.

[0044] Step (3) Preparation of the lower insulating film, as shown in the schematic diagram. Figure 3 As shown: Magnetron sputtering, a physical vapor deposition technique, and aluminum targets with a purity of 99.99% or higher are used as raw materials for preparing alumina insulating films. A first insulating mask 3 is used to cover the sample prepared in step (2), and the sample is placed on the sample stage of the magnetron sputtering equipment. The stage rotation speed is set to 10 r / min. The vacuum acquisition device is turned on, and the vacuum level is maintained at 8 × 10⁻⁶. -4 At Pa, the alumina insulating film was prepared by reactive sputtering. Argon gas at 40 sccm and oxygen gas at 1.5 sccm were introduced, and the purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 150 W. When the power was stable, the sputtering voltage was about 400 V and the sputtering current was about 375 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 120 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the alumina insulating film was prepared based on step (2), which is the lower insulating film f.

[0045] Step (4) Fabrication of the lower central electrode, as shown in the schematic diagram. Figure 4As shown: Magnetron sputtering, a physical vapor deposition technique, and a 99.99% pure Sn metal target were used as raw materials for preparing the n-type gas-sensitive material SnO2. A central electrode mask 5 was used to cover the sample prepared in step (3), and the sample was placed on the sample stage of the magnetron sputtering equipment. The stage rotation speed was set to 10 r / min. The vacuum acquisition device was turned on, and the vacuum level was allowed to reach 8 × 10⁻⁶. -4 At Pa, the gas-sensitive material SnO2 was prepared by reactive sputtering. Argon gas at 45 sccm and oxygen gas at 1.2 sccm were introduced, and the purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 25 W. When the power was stable, the sputtering voltage was about 380 V and the sputtering current was about 66 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 60 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the gas-sensitive material SnO2 center electrode was prepared based on step (3), which is the lower center electrode e. The thickness of the lower center electrode e is the same as the thickness of the lower insulating film f prepared in step (2).

[0046] Step (5) Preparation of the thin film of the gas-sensitive material wire in the middle layer, as shown in the schematic diagram. Figure 5 As shown: Magnetron sputtering, a physical vapor deposition technique, and a 99.99% pure Sn metal target were used as raw materials for preparing the n-type gas-sensitive material SnO2. A wire mask 6 was used to cover the sample prepared in step (4) and placed on the sample stage of the magnetron sputtering equipment. The stage rotation speed was set to 10 r / min. The vacuum acquisition device was turned on, and the vacuum degree was allowed to reach 8 × 10⁻⁶. - 4 At Pa, the gas-sensitive material SnO2 was prepared by reactive sputtering. Argon gas at 45 sccm and oxygen gas at 1.2 sccm were introduced, and the purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 25 W. When the power was stable, the sputtering voltage was about 380 V and the sputtering current was about 66 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 20 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the gas-sensitive material SnO2 wire film was prepared based on step (4), which is the middle layer gas-sensitive material wire film d.

[0047] Step (6) Preparation of the upper insulating film, as shown in the schematic diagram. Figure 6As shown: Magnetron sputtering, a physical vapor deposition technique, and aluminum target material with a purity of 99.99% or higher are used as raw materials for preparing the insulating alumina film. A second insulating mask 4 is used to cover the sample prepared in step (5) and placed on the sample stage of the magnetron sputtering equipment. The rotation speed of the sample stage is set to 10 r / min. The vacuum acquisition device is turned on, and the vacuum degree is waited until it reaches 8 × 10⁻⁶. -4 At Pa, the insulating layer aluminum oxide film was prepared by reactive sputtering. Argon gas at 40 sccm and oxygen gas at 1.5 sccm were introduced, and the purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 150 W. When the power was stable, the sputtering voltage was about 400 V and the sputtering current was about 375 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 120 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the aluminum oxide insulating film was prepared based on step (5), which is the upper insulating film b.

[0048] Step (7) Fabrication of the upper central electrode, as shown in the schematic diagram. Figure 7 As shown: Magnetron sputtering, a physical vapor deposition technique, and a 99.99% pure Sn metal target were used as raw materials for preparing the n-type gas-sensitive material SnO2. A central electrode mask 5 was used to cover the sample prepared in step (6), and the sample was placed on the sample stage of the magnetron sputtering equipment. The stage rotation speed was set to 10 r / min. The vacuum acquisition device was turned on, and the vacuum level was allowed to reach 8 × 10⁻⁶. -4 At Pa, the gas-sensitive material SnO2 was prepared by reactive sputtering. Argon gas at 45 sccm and oxygen gas at 1.2 sccm were introduced, and the purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 25 W. When the power was stable, the sputtering voltage was about 380 V and the sputtering current was about 66 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 60 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the gas-sensitive material SnO2 central electrode, i.e. the upper central electrode c, was prepared based on step (6).

[0049] Step (8) Preparation of the upper gas-sensitive material spiral film, as shown in the schematic diagram. Figure 8 As shown: Magnetron sputtering, a physical vapor deposition technique, and a 99.99% pure Sn target were used as raw materials for preparing the n-type gas-sensitive material SnO2. A second spiral mask 2 was used to cover the sample prepared in step (7) and placed on the sample stage of the magnetron sputtering equipment. The stage rotation speed was set to 10 r / min. The vacuum acquisition device was turned on, and the vacuum degree was allowed to reach 8 × 10⁻⁶.-4 At Pa, the gas-sensitive material SnO2 was prepared by reactive sputtering. Argon gas at 45 sccm and oxygen gas at 1.2 sccm were introduced. The purity of both gases was 99.999%. The working pressure during deposition was controlled by adjusting the vacuum acquisition device. When the working pressure was stable at 0.5 Pa, the DC power supply was turned on and the sputtering power was set to 25 W. When the power was stable, the sputtering voltage was about 380 V and the sputtering current was about 66 mA. After pre-sputtering for 1 h, the baffle was turned on and sputtered for 20 min. After sputtering was completed, the equipment was turned off and the sample was taken out. Finally, the gas-sensitive material SnO2 spiral film was prepared based on step (7), which is the upper gas-sensitive material spiral film a, and the differential decoupled double spiral gas-sensitive gap sensing element was obtained.

[0050] Finally, the method of this invention is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A differentially decoupled dual-helix gas-sensitive gap sensing element, characterized in that... The system comprises a substrate, a lower gas-sensitive material spiral film, a lower insulating film, a lower central electrode, a middle gas-sensitive material conductive film, an upper insulating film, an upper central electrode, and an upper gas-sensitive material spiral film. The lower gas-sensitive material spiral film is situated between the substrate and the lower insulating film, the lower central electrode is located above the lower insulating film, the middle gas-sensitive material conductive film is located between the lower central electrode and the upper insulating film, the upper central electrode is located above the upper insulating film, and the upper gas-sensitive material spiral film is located above the upper central electrode. The upper gas-sensitive material spiral film is exposed to the environment, and changes in the gas atmosphere will lead to… The conductivity of the upper gas-sensitive material spiral film changes; the lower gas-sensitive material spiral film is completely covered by the lower insulating film, so changes in the gas atmosphere do not cause changes in the conductivity of the lower gas-sensitive material spiral film; the voltage across the upper gas-sensitive material spiral film and the voltage across the lower gas-sensitive material spiral film are obtained by a measuring device, and the voltage difference is obtained by differential measurement. According to the "gas concentration-voltage difference" calibration relationship of the sensing element, the concentration signal of the gas being measured can be obtained; the gap signal can be obtained by combining the voltage across the lower gas-sensitive material spiral film with the "gap-voltage" calibration relationship of the sensing element.

2. A method for fabricating the differentially decoupled dual-helix gas-sensitive gap sensing element as described in claim 1 using magnetron sputtering, characterized in that, Includes the following steps: (1) Cleaning of substrate and mask: The substrate and the first spiral mask, the second spiral mask, the first insulating mask, the second insulating mask, the center electrode mask and the wire mask were ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 20 minutes each, and then dried with nitrogen and placed in a fume hood for later use. (2) Preparation of the lower gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first spiral mask is covered on the substrate described in step (1) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the substrate, which is the lower gas-sensitive material spiral film. (3) Preparation of the lower insulating film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the first insulating mask is used to cover the sample prepared in step (2) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the insulating material. Finally, the insulating film is prepared on the sample in step (2), which is the lower insulating film. (4) Preparation of the lower center electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher to prepare gas-sensitive materials, a center electrode mask is used to cover the sample prepared in step (3) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material center electrode is prepared on the sample in step (3), which is the lower center electrode. The thickness of the lower center electrode is consistent with the thickness of the insulating film in step (3). (5) Preparation of intermediate gas-sensitive material wire film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, cover the sample prepared in step (4) with a wire mask and place it at the sample deposition position of the vapor deposition equipment. Open the vacuum acquisition device to obtain the background vacuum required by the process, introduce the process gas, adjust the gate valve of the vacuum acquisition device to control the working pressure required during deposition, turn on the power source, and open the baffle after pre-deposition to realize the deposition of gas-sensitive material. Finally, the gas-sensitive material wire film is prepared on the sample in step (4), which is the intermediate gas-sensitive material wire film. (6) Preparation of the upper insulating film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the sample prepared in step (5) is covered with a second insulating mask and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of the insulating material. Finally, the insulating film is prepared on the sample in step (5), which is the upper insulating film. (7) Preparation of the upper central electrode: Using vapor deposition technology and raw materials with a purity of 99.99% or higher for preparing gas-sensitive materials, a central electrode mask is used to cover the sample prepared in step (6) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after pre-deposition to realize the deposition of gas-sensitive materials. Finally, the gas-sensitive material central electrode is prepared on the sample in step (6), which is the upper central electrode. The thickness of the upper central electrode is consistent with the thickness of the insulating film in step (6). (8) Preparation of upper gas-sensitive material spiral film: Using vapor deposition technology and raw materials with a purity of 99.99% or higher, the second spiral mask is placed on the sample prepared in step (7) and placed at the sample deposition position of the vapor deposition equipment. The vacuum acquisition device is turned on to obtain the background vacuum required by the process, the process gas is introduced, the gate valve of the vacuum acquisition device is adjusted to control the working pressure required during deposition, the power source is turned on, and the baffle is turned on after the pre-deposition is completed to realize the deposition of gas-sensitive material. Finally, the gas-sensitive material spiral film is prepared on the sample in step (7), which is the upper gas-sensitive material spiral film, and the differential decoupled double spiral gas-sensitive gap sensing element is obtained.

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