Cantilever beam hydrogen sensor and calibration method thereof, hydrogen detection system

Abstract

The present application relates to a cantilever beam hydrogen sensor and its calibration method, and a hydrogen detection system. In the cantilever beam hydrogen sensor: a substrate is formed with a groove; two symmetrically arranged cantilever beam structures are arranged on the substrate and are located above the groove; a first gas-sensitive film and a first heating electrode are arranged on the side of one of the cantilever beam structures away from the groove, and the first gas-sensitive film includes a palladium alloy material; a second gas-sensitive film and a second heating electrode are arranged on the side of the other cantilever beam structure away from the groove, and the second gas-sensitive film includes a precious metal-modified metal oxide film; wherein the first heating electrode is connected to a first voltage corresponding to the optimal heating temperature of the first gas-sensitive film, and the second heating electrode is connected to a second voltage corresponding to the optimal heating temperature of the second gas-sensitive film, so as to output a signal representing the ambient hydrogen concentration through the first gas-sensitive film and the second gas-sensitive film, with high sensitivity and accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen sensor chips, and in particular to a cantilever beam hydrogen sensor and a calibration method thereof, and a hydrogen detection system. Background Art

[0002] Hydrogen sensors play a very important role in power transmission line fault detection, insulation aging and overheating detection of power equipment such as transformers, and monitoring of power grid energy storage systems. Monitoring can be achieved by monitoring the concentration of hydrogen. In other words, hydrogen sensors are widely used in various industries such as electricity and new energy. For hydrogen sensors, the sensitivity and accuracy of hydrogen sensors are important factors affecting the detection results, and efforts need to be made to improve the sensitivity and accuracy of hydrogen sensors. Summary of the invention

[0003] Based on this, it is necessary to provide a cantilever beam hydrogen sensor with high sensitivity and high precision and its calibration method and hydrogen detection system to address the above technical problems.

[0004] In a first aspect, a cantilever beam hydrogen sensor is provided, comprising:

[0005] A substrate, wherein a groove is formed on the substrate;

[0006] Two symmetrically arranged cantilever beam structures are arranged on the substrate and located above the groove;

[0007] The first gas-sensitive film and the first heating electrode are both arranged on a side of one of the cantilever beam structures away from the groove, and the first gas-sensitive film comprises a palladium alloy material;

[0008] The second gas-sensitive film and the second heating electrode are both arranged on a side of the other cantilever beam structure away from the groove, and the second gas-sensitive film comprises a noble metal-modified metal oxide film;

[0009] The first heating electrode is connected to a first voltage corresponding to the optimal heating temperature of the first gas-sensitive film, and the second heating electrode is connected to a second voltage corresponding to the optimal heating temperature of the second gas-sensitive film, so as to output a signal representing the concentration of hydrogen in the environment through the first gas-sensitive film and the second gas-sensitive film;

[0010] The optimum heating temperature of the first gas-sensitive film is a temperature within the range of 60° C. to 80° C., and the optimum heating temperature of the second gas-sensitive film is a temperature greater than or equal to 150° C.

[0011] In one embodiment, the palladium alloy material includes any one of PdAg, PdY, PdCu, PdMg, PdNi, and PdAu; and / or the metal oxide film includes any one of SnO2, TiO2, and NiO.

[0012] In one embodiment, the first gas-sensitive film, the second gas-sensitive film, the first heating electrode, and the second heating electrode are all zigzag structures, and a test terminal is provided on each cantilever beam structure;

[0013] The first gas-sensitive film and the first heating electrode are arranged with a spacing between the wirings, and the two ends of the first gas-sensitive film are connected to the two test terminals on the cantilever beam structure correspondingly;

[0014] The wiring of the second gas-sensitive film and the second heating electrode is arranged at intervals, and two ends of the second gas-sensitive film are correspondingly connected to two test terminals on the cantilever beam structure.

[0015] In one embodiment, the first heating electrode, the second heating electrode and the test terminal are all made of gold.

[0016] In one embodiment, the cantilever beam structure is trapezoidal.

[0017] In one embodiment, the noble metal modified metal oxide film is a gold modified nano-tin dioxide film.

[0018] In one embodiment, the cantilever beam structure is obtained by etching a first insulating layer on a substrate.

[0019] In one embodiment, the cantilever beam hydrogen sensor further comprises:

[0020] A second insulating layer is disposed between the substrate and the cantilever beam structure; and / or,

[0021] At least one third insulating layer is disposed on a side of the substrate away from the cantilever beam structure.

[0022] In a second aspect, a calibration method for a cantilever beam hydrogen sensor is provided, which is applied to the cantilever beam hydrogen sensor, and the method comprises:

[0023] Acquiring a first hydrogen concentration and a second hydrogen concentration, wherein the first hydrogen concentration is determined based on a first resistance of the first gas-sensitive film, and the second hydrogen concentration is determined based on a second resistance of the second gas-sensitive film;

[0024] If the difference between the first hydrogen concentration and the second hydrogen concentration is greater than a preset threshold, the test is performed under different hydrogen concentration environments, and at least three first hydrogen concentrations and corresponding at least three second resistances are recorded, wherein the largest first hydrogen concentration is at least 1 times greater than the smallest first hydrogen concentration;

[0025] Substitute the first hydrogen concentration and the corresponding second resistance obtained from multiple sets of tests into the following formula to obtain a new baseline resistance R20 and sensitivity coefficients a and b:

[0026] R2=R20+ax 2+bx, where x is the hydrogen concentration and R2 is the second resistor.

[0027] In a third aspect, a hydrogen detection system is provided, the hydrogen detection system comprising:

[0028] The cantilever beam hydrogen sensor described above;

[0029] The conditioning circuit is respectively connected to the first gas-sensitive film and the second gas-sensitive film of the cantilever beam hydrogen sensor. The conditioning circuit is used to receive a first electrical signal from the first gas-sensitive film and a second electrical signal from the second gas-sensitive film. The first electrical signal is used to characterize the resistance of the first gas-sensitive film, and the second electrical signal is used to characterize the resistance of the second gas-sensitive film:

[0030] The controller is connected with the conditioning circuit and is used for:

[0031] Acquire and determine a first resistance of the first gas-sensitive film and a second resistance of the second gas-sensitive film according to the first electrical signal and the second electrical signal;

[0032] Determining a first hydrogen concentration according to a mapping relationship between the first resistor, the resistance of the first gas-sensitive film, and the hydrogen concentration;

[0033] The second hydrogen concentration is determined according to the second resistor, the baseline resistance of the second gas-sensitive film and the following formula:

[0034] R2=R20+ax 2 +bx, where a and b are sensitivity coefficients, R20 is the baseline resistor, R2 is the second resistor, and x is the hydrogen concentration;

[0035] If the difference between the first hydrogen concentration and the second hydrogen concentration is less than or equal to a preset threshold, a hydrogen detection result is determined according to the first hydrogen concentration and the second hydrogen concentration.

[0036] The above cantilever beam hydrogen sensor and its calibration method, hydrogen detection system. The first gas-sensitive film and the second gas-sensitive film are independently arranged on the two cantilever beam structures, wherein the first gas-sensitive film comprises a palladium alloy material, has stable performance, high precision, and is calibration-free for a long time, and the second gas-sensitive film comprises a noble metal-modified metal oxide film, has a low detection limit and a fast response, and the advantages of the two are combined, and the first heating electrode and the second heating electrode are respectively arranged on the two cantilever beam structures, and the first gas-sensitive film and the second gas-sensitive film are respectively applied with their corresponding optimal heating temperatures, which can take into account the advantages of the two sensitive elements. In addition, the first gas-sensitive film can be calibrated based on its hydrogen measurement results by utilizing the long-term calibration-free characteristic of the first gas-sensitive film, and the second gas-sensitive film can be comprehensively realized with high sensitivity, high precision, and rapid hydrogen detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is one of the structural schematic diagrams of a cantilever beam hydrogen sensor in one embodiment;

[0039] Figure 2 This is a second structural schematic diagram of a cantilever beam hydrogen sensor in one embodiment;

[0040] Figure 3 for Figure 2 Exploded view of the cantilever beam hydrogen sensor;

[0041] Figure 4 for Figure 2 Top view of the cantilever hydrogen sensor;

[0042] Figure 5 for Figure 2 Bottom view of the mid-cantilever hydrogen sensor;

[0043] FIG6 is a schematic diagram showing the principle of realizing hydrogen detection using a palladium-gold alloy material in one embodiment;

[0044] Figure 7 This is a schematic diagram of the structure of gold-modified nano-tin dioxide film;

[0045] Figure 8 is a hydrogen-sensitive characteristic diagram of a first gas-sensitive film based on a palladium-gold alloy material in one embodiment;

[0046] Fig. 9 This is a hydrogen-sensitive characteristic diagram of a second gas-sensitive film based on a gold-modified nano-tin dioxide film in an embodiment;

[0047] Fig.10 A schematic diagram showing that the accuracy of a second gas-sensitive film based on a noble metal-modified metal oxide film decreases over time in one embodiment;

[0048] Fig.11 Schematic diagram of the structure of a hydrogen detection system in one embodiment. DETAILED DESCRIPTION

[0049] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0051] It can be understood that the terms "first", "second", etc. used in the present application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0052] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0053] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0054] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0055] In response to the demand for high-precision and rapid detection of trace hydrogen in scenarios such as leakage during hydrogen storage and transportation, battery thermal runaway, and oil-immersed transformers, the existing MEMS (Micro Electro Mechanical System) palladium-gold alloy sensors still have problems such as small low-concentration detection response, long recovery time, and relatively low sensitivity. MEMS metal oxide hydrogen sensors have problems such as poor stability and low accuracy due to baseline drift and poor selectivity.

[0056] To solve the above problems, the present application provides a cantilever beam hydrogen sensor, such as Figure 1 As shown, it includes: a substrate 10 , two symmetrically arranged cantilever beam structures 20 , a first gas-sensitive film 30 , a second gas-sensitive film 40 , a first heating electrode 50 , and a second heating electrode 60 .

[0057] The substrate 10 is formed with a groove C. Optionally, the groove may be through.

[0058] like Figure 1-Figure 5 As shown, two symmetrically arranged cantilever beam structures 20 are arranged on the substrate 10 and are located above the groove C. Optionally, the two cantilever beam structures can be composed of dielectric films of silicon dioxide or silicon nitride.

[0059] The first gas-sensitive film and the first heating electrode are both arranged on the side of one of the cantilever beam structures away from the groove, and the first gas-sensitive film comprises a palladium alloy material. The second gas-sensitive film and the second heating electrode are both arranged on the side of the other cantilever beam structure away from the groove, and the second gas-sensitive film comprises a noble metal-modified metal oxide film.

[0060] The first heating electrode is connected to a first voltage corresponding to the optimal heating temperature of the first gas-sensitive film, and the second heating electrode is connected to a second voltage corresponding to the optimal heating temperature of the second gas-sensitive film, so as to output a signal representing the ambient hydrogen concentration through the first gas-sensitive film and the second gas-sensitive film.

[0061] The optimal heating temperature of the first gas-sensitive film is within the range of 60°C-80°C, and the optimal heating temperature of the second gas-sensitive film is greater than or equal to 150°C. For example, the optimal heating temperature of the second gas-sensitive film may be within the range of 150°C-200°C.

[0062] The cantilever beam hydrogen sensor provided in the embodiment of the present application has a first gas-sensitive film and a second gas-sensitive film independently arranged on two cantilever beam structures, wherein the first gas-sensitive film includes a palladium alloy material, has stable performance, high precision, and is calibration-free for a long time, and the second gas-sensitive film includes a precious metal-modified metal oxide film, has a low detection limit and a fast response. By combining the advantages of the two, and in conjunction with the first heating electrode and the second heating electrode respectively arranged on the two cantilever beam structures, the first gas-sensitive film and the second gas-sensitive film are respectively applied with their corresponding optimal heating temperatures, thereby taking into account the advantages of the two sensitive elements. In addition, the first gas-sensitive film can be calibrated based on the hydrogen measurement result output by the first gas-sensitive film by utilizing the long-term calibration-free characteristic. High-sensitivity, high-precision, and rapid hydrogen detection can be comprehensively achieved.

[0063] The cantilever beam hydrogen sensor provided in the embodiment of the present application loads a first voltage corresponding to the optimal heating temperature of the first gas-sensitive film through the first heating electrode, so that the first gas-sensitive film works at its corresponding optimal heating temperature, collects the resistance of the first gas-sensitive film in a hydrogen environment, and transmits it to the conditioning circuit in the form of an electrical signal. Similarly, a second voltage corresponding to the optimal heating temperature of the second gas-sensitive film is loaded through the second heating electrode, so that the second gas-sensitive film works at its corresponding optimal heating temperature, collects the resistance of the second gas-sensitive film in a hydrogen environment, and transmits it to the conditioning circuit in the form of an electrical signal. Optionally, the conditioning circuit can convert the resistance into a voltage signal for analysis and calculation.

[0064] In one embodiment, the palladium alloy material includes any one of PdAg, PdY, PdCu, PdMg, PdNi, and PdAu; and / or the metal oxide film includes any one of SnO2, TiO2, and NiO.

[0065] Among them, the first gas-sensitive film formed based on the palladium alloy material can be made of alloy materials such as PdAg, PdY, PdCu, PdMg, PdNi, PdAu, etc. Among these palladium alloy materials, PdAu alloy has better hydrogen detection sensitivity and long-term stability, and can be used as a preferred solution. Taking the palladium-gold alloy material as an example, the working principle of the first gas-sensitive film to realize hydrogen detection is shown in Figure 6. It is mainly that the hydrogen in the measured mixed gas is adsorbed on the surface of the alloy, and decomposes into hydrogen atoms under a certain temperature and adsorption energy. The hydrogen atoms can diffuse into the interior of the alloy and react with the palladium in the alloy, causing the alloy lattice to expand and the electrical properties to change. When other conditions are constant, the greater the concentration of hydrogen in the detected gas, the greater the concentration of hydrogen entering the palladium-gold alloy, which leads to a greater change in the resistance of the palladium-gold alloy structure. Therefore, the resistance of the first gas-sensitive film based on the palladium-gold alloy can reflect the concentration of hydrogen in the gas. Generally, only hydrogen can diffuse into palladium-gold alloys, and the crystal phase of the material is very stable after reasonable heat treatment. Therefore, when detecting the concentration of hydrogen in the mixed gas, there is little cross-interference and good long-term stability, thus ensuring the accuracy of hydrogen detection. In actual use, after calibration, no recalibration is required to ensure high accuracy.

[0066] Among them, metal oxide semiconductors can be prepared into nano-thin films through MEMS processes such as sputtering and electron beam evaporation, and can be modified with precious metals to detect trace amounts of hydrogen. Figure 7 As shown in the figure, since the depletion layer and Debye length are comparable, high-sensitivity and fast-response detection of hydrogen can be achieved.

[0067] For example Figure 8 The hydrogen sensitive characteristic diagram of the first gas sensitive film based on palladium-gold alloy material shown in FIG. Fig. 9 From the hydrogen-sensitive characteristic diagram of the second gas-sensitive film based on Au-modified nano-tin dioxide film, it can be seen that the gas-sensitive film of precious metal-modified nano-metal oxide has higher sensitivity and faster response recovery speed, and has obvious advantages in the detection of trace hydrogen, especially in early warning, it can provide more advance warning.

[0068] As shown in Table 1, the first gas-sensitive film based on palladium alloy material and the second gas-sensitive film based on precious metal modified metal oxide film have their own advantages. The cantilever beam hydrogen sensor provided in the embodiment of the present application truly utilizes the complementary advantages of the two to achieve long-term detection of hydrogen with high sensitivity, high precision, rapidity, and real-time calibration.

[0069] Table 1

[0070]

[0071] In one embodiment, the first gas-sensitive film, the second gas-sensitive film, the first heating electrode and the second heating electrode are all in a zigzag structure, and as Figure 2-Figure 4 As shown, each cantilever beam structure 20 is provided with a test terminal TP;

[0072] The first gas-sensitive film 30 and the first heating electrode 50 are arranged with a spacing, and the two ends of the first gas-sensitive film 30 are connected to the two test terminals TP on the cantilever beam structure.

[0073] The second gas-sensitive film 40 and the second heating electrode 60 are arranged at intervals, and two ends of the second gas-sensitive film 40 are correspondingly connected to two test terminals TP on the cantilever beam structure.

[0074] Under the zigzag structure, the heating electrodes are distributed more evenly, providing a more uniform heating field. In addition, under the zigzag structure, the heating electrodes and the corresponding gas-sensitive films can be arranged in a cross-interval, which is conducive to reducing the volume of the sensor.

[0075] In one embodiment, the first heating electrode and the second heating electrode can be any one of gold, platinum, tungsten, and nickel-chromium alloy. Under this selection, the heating electrode can provide a stable and uniform temperature field for the cantilever hydrogen sensor, thereby improving the sensitivity of the gas-sensitive film, and further improving the sensitivity and response efficiency of the cantilever hydrogen sensor. Exemplarily, the first heating electrode, the second heating electrode, and the test terminal are all made of gold material, so that the heating electrode can provide a uniform temperature field while also having the advantages of high temperature stability and chemical stability, further improving the reliability of the cantilever hydrogen sensor in hydrogen monitoring and detection.

[0076] In one embodiment, Figure 2 and Figure 4 As shown, each cantilever beam structure 20 is provided with a heating terminal HP. Two ends of the first heating electrode 50 are connected to two heating terminals HP on the cantilever beam structure on which it is located, so as to connect a first voltage from the heating terminals HP. Two ends of the second heating electrode 60 are connected to two heating terminals HP on the cantilever beam structure on which it is located, so as to connect a second voltage from the heating terminals HP.

[0077] The test terminal TP and the heating terminal HP may be lead wires PAD formed on the substrate, and may be in various shapes such as round, square, etc., which are not limited here. Optionally, the heating terminal HP may also be made of gold material.

[0078] In one embodiment, if Figure 3-Figure 4As shown, the cantilever beam structure 20 is a trapezoid. The projection of the cantilever beam structure 20 on the plane where the substrate 10 is located is a trapezoid, and the cantilever beam structure 20 extends toward the center of the groove C, and the width of the cantilever beam structure 20 along this direction becomes smaller and smaller. The cantilever beam structure 20 with a trapezoidal structure can have the same stress distribution characteristics in each cross section of the beam. When the first heating electrode and the second heating electrode are working, the cantilever beam structure corresponding to the electrode is warped due to the thermal expansion coefficient, which reduces the stress of the alloy and the heating film, that is, reduces the stress between the gas-sensitive film and the heating electrode, and keeps the strain at each position equal, thereby improving the reliability of the cantilever beam hydrogen sensor.

[0079] Optionally, the cantilever beam structure can be formed by depositing a dielectric film of silicon dioxide or silicon nitride.

[0080] In one embodiment, the noble metal modified metal oxide film is a gold modified nano-tin dioxide film.

[0081] In one embodiment, if Figure 2-Figure 4 As shown, the cantilever beam structure 20 is obtained by etching the first insulating layer 2 on the substrate. Optionally, the first insulating layer 2 may be a silicon nitride insulating layer, which provides better insulation performance while taking into account the film compatibility characteristics.

[0082] In one embodiment, if Figure 2 , Figure 3 and Figure 5 As shown, the cantilever beam hydrogen sensor also includes:

[0083] A second insulating layer 70 is disposed between the substrate 10 and the cantilever beam structure 20; and / or,

[0084] At least one third insulating layer 80 is disposed on a side of the substrate 10 facing away from the cantilever beam structure 20 .

[0085] The second insulating layer may be a silicon oxide insulating layer, which provides better insulating performance while taking into account thin film compatibility characteristics.

[0086] Optional, such as Figure 2-Figure 3 As shown, the third insulating layer 80 is a two-layer stacked layer. The third insulating layer 81 close to the substrate 10 can be a silicon oxide insulating layer, which provides better insulation performance while taking into account the film compatibility characteristics. The third insulating layer 82 away from the substrate 10 is a silicon nitride insulating layer, which provides better insulation performance while taking into account the film compatibility characteristics.

[0087] In order to better illustrate the application of the cantilever beam hydrogen sensor provided in the embodiment of the present application, the following specific embodiments are used as examples, but it should be emphasized that the specific materials used in the examples here do not limit the protection scope of the present application.

[0088] On one cantilever beam structure, a zigzag gas-sensitive film of a PdAu alloy material (a specific form of a first gas-sensitive film) is arranged, and at both ends and the periphery of the first gas-sensitive film, a test end made of Au and a first heating electrode (the heating electrode exists in the form of a film) are arranged respectively; on another cantilever beam structure, a zigzag gas-sensitive film of a noble metal-modified tin dioxide (SnO2) material (a specific form of a second gas-sensitive film) is arranged, and at both ends and the periphery of the sensitive structure, a test end made of Au and a second heating electrode (the heating electrode exists in the form of a film) are arranged respectively; the above-mentioned gas-sensitive film and the heating electrode are both zigzag structures, and the position distribution between the gas-sensitive film and the corresponding heating electrode is as follows: Figure 1-Figure 4 The fork-tooth electrode form shown; the test end is correspondingly connected to the two ends of the fold line of the gas-sensitive film to perform hydrogen concentration testing.

[0089] The substrate of the cantilever beam hydrogen sensor can be a silicon substrate, the silicon wafer is double-sided polished, and the silicon dioxide and silicon nitride insulating layers are prepared by double-sided thermal oxidation and nitridation processes. Figure 4 The deposition of the front material PdAu (the constituent material of the first gas-sensitive film), SnO2 (the metal oxide material of the second gas-sensitive film), and Au (the constituent material of the heating electrode and the test end) under the viewing angle shown can be completed by magnetron sputtering or electron beam evaporation. The release of the front silicon nitride, silicon oxide, and silicon substrate (corresponding to the substrate and the first insulating layer) is completed by dry etching combined with wet etching to form a cantilever beam.

[0090] When used, the voltage corresponding to the optimal working temperature of the palladium-gold alloy (PdAu) and the noble metal modified tin dioxide gas-sensitive material is applied to the first heating electrode and the second heating electrode on the corresponding two cantilever beam structures. The disadvantages of the gas-sensitive thin film element of palladium-gold alloy are slow response speed and relatively high detection limit, and the advantages are stable performance, high precision, and no calibration is required after long-term work; the advantages of the gas-sensitive element of the noble metal modified tin dioxide film are low detection limit (as low as sub-ppm) and fast response (low concentration can be better than 10s), and the disadvantages are that the baseline is easy to drift during long-term work, the sensitivity is easy to degrade, and the cross-interference is serious under complex gas background. To this end, in view of the shortcomings of the two sensitive materials, a calibration method of the cantilever beam hydrogen sensor described in the following embodiment is adopted, so that the hydrogen sensor can be compatible with the advantages of the components prepared by the two sensitive materials, and achieves high sensitivity, high precision, and rapid hydrogen concentration detection.

[0091] A cantilever beam hydrogen sensor provided in an embodiment of the present application realizes accurate detection of hydrogen without calibration through the sensitive part of the palladium alloy, and further utilizes the hydrogen detection result of the palladium alloy to dynamically calibrate the sensitive part of the precious metal modified metal oxide film, so that it has high sensitivity and fast response while ensuring the accuracy of measurement, thereby realizing fast, highly sensitive and high-precision detection of hydrogen concentration.

[0092] The baseline of the second gas-sensitive film based on the noble metal-modified metal oxide film is prone to drift, and it is difficult to recalibrate in practical applications. As time goes by, the accuracy of the hydrogen sensor will be significantly reduced. Fig.10 In view of this, in one embodiment, a calibration method for a cantilever beam hydrogen sensor is also provided, which is applied to the above cantilever beam hydrogen sensor, and the method is used to calibrate the second gas sensitive film in the hydrogen sensor. Specifically, the method includes:

[0093] Acquiring a first hydrogen concentration and a second hydrogen concentration, wherein the first hydrogen concentration is determined based on a first resistance of the first gas-sensitive film, and the second hydrogen concentration is determined based on a second resistance of the second gas-sensitive film;

[0094] If the difference between the first hydrogen concentration and the second hydrogen concentration is greater than a preset threshold, the test is performed under different hydrogen concentration environments, and at least three first hydrogen concentrations and corresponding at least three second resistances are recorded, wherein the largest first hydrogen concentration is at least 1 times greater than the smallest first hydrogen concentration;

[0095] Substitute the first hydrogen concentration and the corresponding second resistance obtained from multiple sets of tests into the following formula to obtain a new baseline resistance R20 and sensitivity coefficients a and b:

[0096] R2=R20+ax 2 +bx, where x is the hydrogen concentration and R2 is the second resistor.

[0097] In a certain small range of precious metal modified metal oxide film, the relationship between the hydrogen concentration and resistance in the environment can be simplified as follows:

[0098] R2=R20+ax 2 +bx

[0099] During use, due to the long-term stability of palladium alloy, it can be considered that the corresponding relationship R1=f1(c) between the resistance and concentration of the first gas-sensitive film based on the palladium alloy material does not change; however, as time goes by, the baseline resistance R20 of the noble metal-modified metal oxide film, and the coefficients a and b reflecting its sensitivity will change, resulting in a certain error in the result of converting the second resistance measured by the noble metal-modified metal oxide film into the second hydrogen concentration; during use, for the output result of the same concentration of hydrogen, when the difference between the first hydrogen concentration measured based on the first gas-sensitive film and the second hydrogen concentration measured based on the second gas-sensitive film is greater than a preset threshold value (for example, 10%), it means that the noble metal-modified metal oxide film has a certain drift error. At this time, it is necessary to recalibrate the relationship between the second resistance of the noble metal-modified metal oxide film and the hydrogen concentration measured according to the first hydrogen concentration. The calibration steps are as follows:

[0100] At least three first hydrogen concentrations x1, x2, x3 measured by the first gas-sensitive film under different concentration environments are recorded, and the maximum concentration is at least 1 times greater than the minimum concentration.

[0101] At the same time, the second resistance R2I, R2II, and R2III measured by the second gas-sensitive film are recorded to form three groups of data (x1, R2I), (x2, R2II), and (x3, R2III) and substituted into the formula R2=R20+ax2+bx for solution to obtain new R20, a, and b.

[0102] By utilizing the hydrogen detection results of the first gas sensitive film with good long-term stability, the hydrogen detection of the second gas sensitive film based on the precious metal modified metal oxide film is dynamically calibrated, and the rapid, high-sensitivity and high-precision detection of hydrogen is achieved in combination with the precious metal modified metal oxide film.

[0103] In one embodiment, Fig.11 As shown, a hydrogen detection system is provided, which includes: the above-mentioned cantilever beam hydrogen sensor 100, a conditioning circuit 200, and a controller 300.

[0104] The conditioning circuit is respectively connected to the first gas-sensitive film and the second gas-sensitive film of the cantilever beam hydrogen sensor. The conditioning circuit is used to receive a first electrical signal from the first gas-sensitive film and a second electrical signal from the second gas-sensitive film. The first electrical signal is used to characterize the resistance of the first gas-sensitive film, and the second electrical signal is used to characterize the resistance of the second gas-sensitive film:

[0105] The controller is connected to the conditioning circuit and is used to:

[0106] Acquire and determine a first resistance of the first gas-sensitive film and a second resistance of the second gas-sensitive film according to the first electrical signal and the second electrical signal;

[0107] Determine a first hydrogen concentration according to a mapping relationship between the first resistor, the first resistance of the first gas-sensitive film, and the hydrogen concentration;

[0108] The second hydrogen concentration is determined according to the second resistor, the baseline resistance of the second gas-sensitive film and the following formula:

[0109] R2=R20+ax 2 +bx, where a and b are sensitivity coefficients, R20 is the baseline resistor, R2 is the second resistor, and x is the hydrogen concentration;

[0110] If the difference between the first hydrogen concentration and the second hydrogen concentration is less than or equal to a preset threshold, a hydrogen detection result is determined according to the first hydrogen concentration and the second hydrogen concentration.

[0111] Through multi-point calibration before use, the relationship between the output resistance and hydrogen concentration of the two gas-sensitive films can be obtained, which are:

[0112] R1=f1(c) (1)

[0113] R2=f2(c). This establishes the relationship between the resistance and concentration of the two components.

[0114] In a certain small range of precious metal modified metal oxide films, the relationship between concentration and resistance can be simplified as follows:

[0115] R2=R20+ax 2 +bx (2)

[0116] To better illustrate the working process of the hydrogen detection system provided in the embodiment of the present application, Figure 4 The working process of the above hydrogen detection system is introduced under the cantilever beam hydrogen sensor shown in the figure. Under this view:

[0117] On the left cantilever beam structure, a zigzag sensitive structure made of a gas-sensitive film of a palladium alloy, a heating electrode composed of gold, and a test end are designed; on the right cantilever beam structure, a zigzag sensitive structure made of a gas-sensitive film of a noble metal-modified tin dioxide, a heating electrode composed of gold, and a test end are designed. The heating electrodes of the cantilever beam structures on the left and right sides are independently loaded with voltage to achieve different optimal heating temperature controls, and the resistance of the palladium-gold alloy sensitive structure and the noble metal-modified tin dioxide is connected to a dedicated conditioning circuit through the corresponding test end, which can read the resistance value and convert it into a voltage signal.

[0118] The hydrogen concentration in the measured air is x, the first resistance of the first gas sensitive film is R1, and the second resistance of the second gas sensitive film is R2. If the hydrogen concentration is 0, the outputs are the respective baseline resistances R10 and R20.

[0119] If the first gas-sensitive film detects that the first hydrogen concentration is extremely low or no hydrogen, and the second gas-sensitive film detects that there is a large hydrogen concentration output, then only baseline calibration is required. That is, the hydrogen concentration in formula (2) is set to zero. At this time, the second resistance of the second gas-sensitive film is the new baseline resistance R20. In this way, the second gas-sensitive film can be dynamically corrected in real time, so that its output has the same stability as the first gas-sensitive film, and its rapidity and high sensitivity during detection are maintained.

[0120] During the detection process, voltage is applied to the heating electrodes on the corresponding two cantilever beam structures according to the optimal operating temperatures of the palladium alloy material and the precious metal modified metal oxide film, so as to obtain the first resistance and the second resistance through the conditioning circuit, and the first hydrogen concentration is determined according to the first resistance, and the second hydrogen concentration is determined according to the second resistance. Based on the two concentration detection results, the hydrogen detection result is finally determined, and the detection speed is fast and has high sensitivity and high precision.

[0121] In one embodiment, the controller is further connected to the first heating electrode and the second heating electrode to provide the first voltage and the second voltage.

[0122] In one embodiment, a method for preparing the cantilever beam hydrogen sensor is provided, comprising:

[0123] Providing a substrate, wherein the substrate has a groove;

[0124] A first insulating layer is formed on the substrate, and the first insulating layer is processed by dry etching combined with wet etching to form two symmetrical cantilever beam structures;

[0125] On one side of the cantilever beam structure away from the groove, a first gas-sensitive film and a first heating electrode are formed by magnetron sputtering or electron beam evaporation, wherein the first gas-sensitive film comprises a palladium alloy material;

[0126] On the side of the other cantilever beam structure away from the groove, a second gas sensitive film and a second heating electrode are formed by magnetron sputtering or electron beam evaporation, wherein the second gas sensitive film includes a noble metal modified metal oxide film to form a cantilever beam hydrogen sensor.

[0127] In one embodiment, the preparation method further comprises:

[0128] A first gas-sensitive film and a first heating electrode in the form of a zigzag line are formed on the cantilever beam structures at both sides, and a second gas-sensitive film and a second heating electrode in the form of a zigzag line are formed.

[0129] Two pairs of test ends are formed correspondingly at two ends of the fold line of the first gas-sensitive film and two ends of the fold line of the second gas-sensitive film on the cantilever beam structures at both sides;

[0130] Two pairs of heating ends are formed at both ends of the fold line of the first heating electrode and at both ends of the fold line of the second heating electrode.

[0131] The cantilever beam hydrogen sensor has a simple processing technology, reliable performance, and convenient use. It can be widely used in high-precision detection of hydrogen concentration in various scenarios to avoid false alarms and false reports during hydrogen detection warnings.

[0132] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0133] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0134] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A cantilever beam hydrogen sensor, characterized in that: include: A substrate, wherein a groove is formed on the substrate; Two symmetrically arranged cantilever beam structures are arranged on the substrate and located above the groove; The first gas-sensitive film and the first heating electrode are both arranged on a side of one of the cantilever beam structures away from the groove, and the first gas-sensitive film comprises a palladium alloy material; A second gas-sensitive film and a second heating electrode are both arranged on a side of the other cantilever beam structure away from the groove, and the second gas-sensitive film comprises a noble metal-modified metal oxide film; The first heating electrode is connected to a first voltage corresponding to the optimal heating temperature of the first gas-sensitive film, and the second heating electrode is connected to a second voltage corresponding to the optimal heating temperature of the second gas-sensitive film, so as to output a signal representing the ambient hydrogen concentration through the first gas-sensitive film and the second gas-sensitive film; The optimum heating temperature of the first gas-sensitive film is a temperature within a range of 60° C. to 80° C., and the optimum heating temperature of the second gas-sensitive film is a temperature greater than or equal to 150° C.

2. The cantilever beam hydrogen sensor according to claim 1, characterized in that: The palladium alloy material includes any one of PdAg, PdY, PdCu, PdMg, PdNi, and PdAu; and / or the metal oxide film includes any one of SnO2, TiO2, and NiO.

3. The cantilever beam hydrogen sensor according to claim 1, characterized in that: The first gas-sensitive film, the second gas-sensitive film, the first heating electrode and the second heating electrode are all zigzag structures, and each of the cantilever beam structures is provided with a test terminal; The first gas-sensitive film and the first heating electrode are arranged at intervals, and two ends of the first gas-sensitive film are connected to two test terminals on the cantilever beam structure correspondingly; The wiring of the second gas-sensitive film and the second heating electrode is arranged at intervals, and two ends of the second gas-sensitive film are correspondingly connected to two test terminals on the cantilever beam structure.

4. The cantilever beam hydrogen sensor according to claim 3, characterized in that: The first heating electrode, the second heating electrode and the test terminal are all made of gold.

5. The cantilever beam hydrogen sensor according to claim 1, characterized in that: The cantilever beam structure is trapezoidal.

6. The cantilever beam hydrogen sensor according to claim 1, characterized in that: The noble metal modified metal oxide film is a gold modified nano tin dioxide film.

7. The cantilever beam hydrogen sensor according to any one of claims 1 to 6, characterized in that: The cantilever beam structure is obtained by etching the first insulating layer on the substrate.

8. The cantilever beam hydrogen sensor according to any one of claims 1 to 6, characterized in that: Also includes: A second insulating layer is disposed between the substrate and the cantilever beam structure; and / or, At least one third insulating layer is disposed on a side of the substrate away from the cantilever beam structure.

9. A method for calibrating a cantilever beam hydrogen sensor, characterized in that: Applied to the cantilever beam hydrogen sensor according to any one of claims 1 to 8, the method comprising: Acquiring a first hydrogen concentration and a second hydrogen concentration, wherein the first hydrogen concentration is determined based on a first resistance of the first gas-sensitive film, and the second hydrogen concentration is determined based on a second resistance of the second gas-sensitive film; If the difference between the first hydrogen concentration and the second hydrogen concentration is greater than a preset threshold, test under different hydrogen concentration environments, and record at least three first hydrogen concentrations and corresponding at least three second resistances, wherein the largest first hydrogen concentration is at least 1 times greater than the smallest first hydrogen concentration; Substitute the first hydrogen concentration and the corresponding second resistance obtained from multiple sets of tests into the following formula to obtain a new baseline resistance R20 and sensitivity coefficients a and b: R2=R20+ax 2 +bx, where x is the hydrogen concentration and R2 is the second resistor.

10. A hydrogen detection system, characterized in that: The hydrogen detection system comprises: The cantilever beam hydrogen sensor according to any one of claims 1 to 8; A conditioning circuit is respectively connected to the first gas-sensitive film and the second gas-sensitive film of the cantilever beam hydrogen sensor, and the conditioning circuit is used to receive a first electrical signal from the first gas-sensitive film and a second electrical signal from the second gas-sensitive film, wherein the first electrical signal is used to characterize the resistance of the first gas-sensitive film, and the second electrical signal is used to characterize the resistance of the second gas-sensitive film: A controller connected to the conditioning circuit, the controller being used for: Acquire and determine a first resistance of the first gas-sensitive film and a second resistance of the second gas-sensitive film according to the first electrical signal and the second electrical signal; Determine a first hydrogen concentration according to a mapping relationship between the first resistor, the resistance of the first gas-sensitive film, and the hydrogen concentration; The second hydrogen concentration is determined according to the second resistor, the baseline resistance of the second gas-sensitive film and the following formula: R2=R20+ax 2 +bx, where a and b are sensitivity coefficients, R20 is the baseline resistance, R2 is the second resistance, and x is the hydrogen concentration; If the difference between the first hydrogen concentration and the second hydrogen concentration is less than or equal to a preset threshold, a hydrogen detection result is determined according to the first hydrogen concentration and the second hydrogen concentration.

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