Thermal conductivity gas sensor, preparation method, and method for measuring thermal conductivity of gas

Abstract

A thermal conductivity gas sensor, a preparation method, and a method for measuring thermal conductivity of a gas. The thermal conductivity gas sensor comprises a substrate (1) provided with a suspension recess (11), and a temperature field layer (2) that is at least partially suspended on the suspension recess (11); the temperature field layer (2) comprises a constant-temperature heat source (21) and at least two temperature measurement units (22) that are arranged at intervals; the suspension recess (11) is used for accommodating a gas to be measured; at least some of the at least two temperature measurement units (22) are arranged at unequal distances from the constant-temperature heat source (21). By using the asymmetric temperature field measurement technology, the at least two temperature measurement units (22) are arranged at unequal distances from the constant-temperature heat source (21) in the suspended temperature field layer (2), and the temperature field of the gas to be measured in the suspension recess (11) is measured, so that the thermal conductivity of said gas can be calculated by means of the drift of isothermal lines in the temperature field.

Description

Thermal conductivity gas sensor, preparation method and gas thermal conductivity detection method TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal conductivity measurement, in particular to a thermal conductivity gas sensor, a preparation method and a gas thermal conductivity detection method. BACKGROUND

[0002] The measurement of the thermal conductivity of a gas usually adopts a hot-wire method, and the basic method is to place a thin and long wire (usually a resistance wire) in the gas to be measured, heat the wire through an electric current, raise the temperature of the wire, and generate a temperature field in the gas to be measured around the wire; then, by measuring the change of the wire temperature (usually the resistance) over time, the thermal conductivity of the gas to be measured can be calculated according to the heat conduction equation; however, the devices using the hot-wire method principle for measurement in the prior art are extremely susceptible to environmental temperature interference, and even if temperature compensation is used, the compensation effect is very limited, and the lower limit of detection and the precision of the sensor cannot be further improved.

[0003] SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a thermal conductivity gas sensor, a preparation method and a gas thermal conductivity detection method, and the technical solution is as follows:

[0005] In one aspect, the present application provides a thermal conductivity gas sensor, comprising a substrate provided with a suspended slot and a temperature field layer at least partially suspended on the suspended slot, the temperature field layer comprising a constant temperature heat source and at least two temperature measurement units arranged at intervals; the suspended slot is used to accommodate the gas to be measured, and the distance between at least part of the temperature measurement units in the at least two temperature measurement units and the constant temperature heat source is arranged at unequal intervals.

[0006] Further, the constant temperature heat source and the at least two temperature measurement units are located in the same plane.

[0007] Further, the temperature measurement unit comprises a plurality of temperature measurement points, and in the same temperature measurement unit, at least part of the temperature measurement points in the plurality of temperature measurement points are located on a plurality of isotherms in the same plane; in different temperature measurement units, at least part of the temperature measurement points of the at least two temperature measurement units are located on the same isotherm.

[0008] Further, the at least two temperature measurement units are located on the same side of the constant temperature heat source; or

[0009] At least two temperature measurement units are distributed on both sides of the constant temperature heat source.

[0010] Further, the temperature field layer satisfies at least one of the following characteristics:

[0011] In the at least partially non-equidistantly arranged temperature measuring units, a distance between at least one of the temperature measuring units and the constant temperature heat source is 1-10 μm, and a distance between at least another of the temperature measuring units and the constant temperature heat source is 2-50 μm.

[0012] In the at least partially non-equidistantly arranged temperature measuring units, a difference between the distance between at least one of the temperature measuring units and the constant temperature heat source and the distance between at least another of the temperature measuring units and the constant temperature heat source is 1-40 μm.

[0013] Further, the constant temperature heat source and the at least two temperature measuring units are in a strip shape, and are arranged in parallel in the same plane.

[0014] Further, the temperature field layer comprises a composite dielectric layer and a patterned metal layer, the composite dielectric layer comprises mutually connected suspended parts and support parts, the support parts are located on the substrate, the suspended parts are located on the suspended grooves, and the metal layer is located in the suspended parts, and the metal layer comprises the constant temperature heat source and the at least two temperature measuring units.

[0015] Further, the composite dielectric layer comprises a first dielectric layer, a second dielectric layer and a third dielectric layer, the first dielectric layer is located on the substrate, the metal layer is located between the first dielectric layer and the second dielectric layer, and the third dielectric layer is located on the second dielectric layer; and the temperature field layer satisfies at least one of the following characteristics:

[0016] The thickness of the first dielectric layer is 0.5-1.5 μm;

[0017] The thickness of the second dielectric layer is 0.5-1.5 μm;

[0018] The thickness of the third dielectric layer is 0.1-0.3 μm;

[0019] The thickness of the metal layer is 200-800 nm.

[0020] Further, the metal layer further comprises at least one reinforcing structure, the reinforcing structure is located on a side of the temperature measuring unit away from the constant temperature heat source, the reinforcing structure penetrates the suspended groove and is connected to an end of the support part located on a side wall of the suspended groove.

[0021] Further, the thermal conductivity gas sensor further comprises a pad, the pad is located on the support part of the composite dielectric layer, and the pad is electrically connected to an end of the metal layer.

[0022] In another aspect, the application further provides a preparation method of the thermal conductivity gas sensor, comprising:

[0023] Forming a temperature field layer on a substrate with a suspended groove; the temperature field layer is at least partially suspended in the suspended groove, and the temperature field layer comprises a constant temperature heat source and at least two temperature measuring units arranged at intervals; the suspended groove is used to accommodate a gas to be measured, and at least part of the at least two temperature measuring units is arranged at a non-equidistant distance from the constant temperature heat source.

[0024] Further, the forming of the temperature field layer on the substrate with the suspended groove comprises:

[0025] forming a first initial medium layer on the surface of the initial substrate;

[0026] forming a patterned metal layer on the first initial medium layer;

[0027] forming a second initial medium layer and a third initial medium layer on the metal layer to obtain an initial temperature field layer; the initial temperature field layer comprises the first initial medium layer, the metal layer, the second initial medium layer and the third initial medium layer;

[0028] performing a patterning process on the initial temperature field layer to obtain the temperature field layer; the temperature field layer comprises the constant temperature heat source and the at least two temperature measuring units arranged at intervals;

[0029] performing wet etching on the initial substrate to remove the substrate material at the bottom of the temperature field layer to form a suspended groove, thereby obtaining a thermal conductivity gas sensor; the thermal conductivity gas sensor comprises the substrate with the suspended groove and the temperature field layer at least partially suspended in the suspended groove.

[0030] In another aspect, the application also provides a gas thermal conductivity detection method based on the thermal conductivity gas sensor according to any one of the above, which comprises:

[0031] passing the gas to be measured into the suspended groove and obtaining a temperature measurement data set of the at least two temperature measuring units during the heating of the constant temperature heat source; the temperature measurement data set comprises temperature information of multiple positions in the suspended groove;

[0032] performing temperature field calculation based on the temperature measurement data set and distance information between the at least two temperature measuring units to obtain temperature field information of the constant temperature heat source in the suspended groove; the distance information is used to indicate the distance between the at least two temperature measuring units and the constant temperature heat source; and the temperature field information is used to indicate the isotherm distribution state of the gas to be measured around the constant temperature heat source;

[0033] performing thermal conductivity conversion calculation based on the temperature field information to obtain the thermal conductivity of the gas to be measured.

[0034] The implementation of the application has the following beneficial effects:

[0035] 1、The application adopts asymmetric temperature field measurement technology, at least two temperature measurement units are arranged non-equidistantly with the constant temperature heat source in the suspended temperature field layer, the temperature field of the to-be-measured gas in the suspended groove is measured, the thermal conductivity of the to-be-measured gas can be calculated through the drift of each isotherm in the temperature field, the interference caused by the ambient temperature is effectively eliminated, temperature compensation is not needed, and the detection sensitivity and detection precision of the thermal conductivity gas sensor can be greatly improved.

[0036] 2、The at least two temperature measurement units of the application are distributed on both sides of the constant temperature heat source, the arrangement is convenient and low in difficulty, the temperature measurement units are distributed relatively dispersedly, which is beneficial to improving the accuracy of temperature measurement, and can avoid that part of the temperature measurement units are located between the constant temperature heat source and the remote temperature measurement units, thereby producing adverse effects on the isotherm distribution of the constant temperature heat source in the to-be-measured gas and the temperature detection results of the remote temperature measurement units, which is beneficial to further improving the measurement accuracy and measurement reliability of the overall temperature and temperature field, and further improving the measurement accuracy and measurement reliability of the thermal conductivity of the to-be-measured gas. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the application, the drawings used in the embodiments will be briefly introduced as follows, wherein the same parts are denoted by the same reference numerals. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0038] Fig. 1 is a top view of a thermal conductivity gas sensor provided by an embodiment of the application;

[0039] Fig. 2 is a schematic diagram of the principle of a thermal conductivity gas sensor provided by an embodiment of the application;

[0040] Fig. 3 is a sectional view of a thermal conductivity gas sensor provided by an embodiment of the application;

[0041] Fig. 4 is a logic structure diagram of a gas thermal conductivity detection method provided by an embodiment of the application.

[0042] Among them, the reference numerals are:

[0043] 1-substrate, 11-suspended groove, 2-temperature field layer, 21-constant temperature heat source, 22-temperature measurement unit, 23-composite dielectric layer, 230-suspended part, 231-supporting part, 24-metal layer, 240-strengthening structure, 3-pad. DETAILED DESCRIPTION

[0044] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and therefore should not be considered as limitations to the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0045] It should be noted that in the description of the present application, the following defined terms should be applied to the description unless a different definition is provided in the claims or elsewhere in the specification. All numerical values are defined as being "about" unless explicitly indicated otherwise. The term "about" generally means a range of values that one of ordinary skill in the art would consider as the equivalent of the value stated to produce substantially the same property, function, result, etc. A numerical range expressed by a low value and a high value is defined to include all numerical values falling within the range, and all sub-ranges included within the range.

[0046] It should be noted that the terms "first", "second", and the like in the description of the present application are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the objects thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated below or described below. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product including a series of steps or units does not necessarily limit to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, or product.

[0047] In order to solve the problem that the way of measuring the thermal conductivity of gas by using hot-wire method in the prior art is easily disturbed by ambient temperature, even if temperature compensation is used, the compensation effect is very limited, resulting in low detection sensitivity and detection accuracy, the embodiments of the present application provide a thermal conductivity gas sensor, a preparation method and a gas thermal conductivity detection method, as shown in FIG. 1, the thermal conductivity gas sensor comprises a substrate 1 provided with a suspended groove 11 and a temperature field layer 2 at least partially suspended on the suspended groove 11, the temperature field layer 2 comprises a constant temperature heat source 21 and at least two temperature measuring units 22 arranged at intervals, at least part of the at least two temperature measuring units 22 is arranged at a non-equal distance from the constant temperature heat source 21, the constant temperature heat source 21 is used to emit heat, the suspended groove 11 is used to accommodate the gas to be measured and provide heat generated by the constant temperature heat source 21 for heat conduction in the gas to be measured, and the temperature measuring unit 22 is used to measure the temperature field (referred to as temperature field) at the position where the temperature measuring unit 22 is located.

[0048] The heat-conducting gas sensor is supplied with a to-be-detected gas, which can be distributed in the overhanging groove 11 and the space between the constant-temperature heat source 21 and the at least two temperature measuring units 22. During the heating of the constant-temperature heat source 21, heat can be conducted in the to-be-detected gas around the constant-temperature heat source 21, so as to form a temperature field in the to-be-detected gas, which has a plurality of isotherms with different temperatures. The isotherms are densely distributed in a position close to the constant-temperature heat source 21, and the density of the isotherms gradually decreases with the increase of the distance from the constant-temperature heat source 21. Then, the temperature in the temperature field can be asymmetrically detected by the at least two temperature measuring units 22 arranged in a non-equidistant manner. The number or density of the isotherms measured by the at least two temperature measuring units 22 arranged in a non-equidistant manner is different, and then the thermal conductivity of the to-be-detected gas is calculated according to the difference in the temperature field between the at least two temperature measuring units 22. The interference of the ambient temperature can be effectively eliminated, and temperature compensation is not required, so that the detection sensitivity, detection accuracy and detection stability of the heat-conducting gas sensor can be greatly improved. In some exemplary embodiments, the heat-conducting gas sensor can be a MEMS heat-conducting gas sensor.

[0049] As shown in FIG. 2, the thermal conductivities (or thermal conductive coefficients) of the plurality of to-be-detected gases are different, and correspondingly, the temperature fields formed by the constant-temperature heat source 21 in different to-be-detected gases are also different, i.e., the distribution densities of the isotherms in the temperature fields are different. If the thermal conductivity of the to-be-detected gas increases, the distribution sparseness of the isotherms in the temperature field in space increases. Conversely, if the thermal conductivity of the to-be-detected gas decreases, the distribution density of the isotherms in the temperature field in space increases. The temperature field is formed in the to-be-detected gas around the constant-temperature heat source 21, and asymmetric measurement is performed by the at least two temperature measuring units arranged in a non-equidistant manner from the constant-temperature heat source 21, so as to obtain the isotherm distribution state of the temperature field, i.e., the temperature changing with the distance in the to-be-detected gas. The isotherm distribution state is associated with the thermal conductivity of the to-be-detected gas, and then the thermal conductivity of the to-be-detected gas can be solved according to the isotherm distribution state.

[0050] It can be understood that the number of temperature measurement units 22 in the temperature field layer 2 can be any positive integer greater than or equal to 2; for example, the number of temperature measurement units 22 in the temperature field layer 2 can be 2, 3, 4, 5, etc.; in some exemplary embodiments, the temperature field layer 2 includes two temperature measurement units 22, and the spacing between the two temperature measurement units 22 and the constant temperature heat source 21 is non-equidistant, that is, the spacing between one temperature measurement unit 22 and the constant temperature heat source 21 is less than or greater than the spacing between the other temperature measurement unit 22 and the constant temperature heat source, which is simple and convenient to arrange, and is conducive to reducing the cost of the thermal conductivity gas sensor, and the two temperature measurement units 22 have high measurement accuracy and are not easily disturbed; in other exemplary embodiments, the temperature field layer 2 includes three temperature measurement units 22, at least two of which are non-equidistantly arranged with the constant temperature heat source 21, and the three temperature measurement units 22 include a first temperature measurement unit, a second temperature measurement unit, and a third temperature measurement unit, which can be non-equidistantly arranged with the constant temperature heat source 21, that is, the spacing between the first temperature measurement unit and the constant temperature heat source 21, the spacing between the second temperature measurement unit and the constant temperature heat source 21, and the spacing between the third temperature measurement unit and the constant temperature heat source 21 are all different; in other exemplary embodiments, two of the three temperature measurement units 22 are non-equidistantly arranged with the constant temperature heat source 21, for example, the spacing between the first temperature measurement unit and the constant temperature heat source 21 is equal to the spacing between the second temperature measurement unit and the constant temperature heat source 21, which is conducive to improving the temperature measurement accuracy of the first temperature measurement unit and the second temperature measurement unit, and the spacing between the third temperature measurement unit and the constant temperature heat source 21 is greater than the spacing between the first temperature measurement unit and the constant temperature heat source 21, which is convenient for asymmetric measurement with the first temperature measurement unit (or the second temperature measurement unit), eliminates the interference of the ambient temperature, and improves the overall detection accuracy and detection sensitivity of the thermal conductivity gas sensor.

[0051] Specifically, the constant temperature heat source 21 and the at least two temperature measurement units 22 are located in the same plane, which can avoid the difference in the influence of different environmental conditions in different three-dimensional space directions on heat conduction, is conducive to improving the accuracy of the measured temperature field and each isotherm therein, and further improves the detection accuracy, detection stability, and detection reliability of the thermal conductivity of the gas to be measured; in some exemplary embodiments, the constant temperature heat source 21 and the at least two temperature measurement units 22 are located in the same vertical plane; in other exemplary embodiments, the constant temperature heat source 21 and the at least two temperature measurement units 22 are located in the same horizontal plane, which is convenient for detection, has high detection accuracy, and is simple and convenient to arrange, and has low cost.

[0052] Specifically, in some exemplary embodiments, the at least two temperature measurement units 22 are located on the same side of the constant temperature heat source 21; for example, the temperature field layer 2 includes two temperature measurement units 22, and the two temperature measurement units 22 are located on the same side of the constant temperature heat source 21; for example, the temperature field layer 2 includes three temperature measurement units 22, and the three temperature measurement units 22 are all located on the same side of the constant temperature heat source 21, which is flexible in arrangement.

[0053] Specifically, in some exemplary embodiments, at least two temperature measuring units 22 are distributed on both sides of the constant temperature heat source 21, that is, at least one of the at least two temperature measuring units 22 is located on one side of the constant temperature heat source 21, and another temperature measuring unit 22 is located on the other side of the constant temperature heat source 21. The arrangement is convenient and low in difficulty, and the temperature measuring units 22 are distributed relatively dispersedly, which is beneficial to improve the accuracy of temperature measurement. In addition, it can avoid the temperature measuring unit 22 located between the constant temperature heat source 21 and the remote temperature measuring unit 22 to have an adverse effect on the isothermal line distribution of the constant temperature heat source 21 in the gas to be measured, and also avoid the temperature detection result of the remote temperature measuring unit 22 to have an adverse effect, which is beneficial to further improve the measurement sensitivity, measurement accuracy and measurement reliability of the overall temperature and temperature field, and further improve the measurement accuracy and measurement reliability of the thermal conductivity of the final gas to be measured. For example, the temperature field layer 2 includes two temperature measuring units 22, and the two temperature measuring units 22 are distributed on both sides of the constant temperature heat source 21. For example, the temperature field layer 2 includes three temperature measuring units 22, two of which are located on one side of the constant temperature heat source 21, and the other is located on the other side of the constant temperature heat source 21. The arrangement is flexible.

[0054] Specifically, the temperature measuring unit 22 includes a plurality of temperature measuring points. In the same temperature measuring unit 22, at least part of the plurality of temperature measuring points are respectively located on a plurality of isothermal lines in the same plane, that is, the temperature measuring unit 22 has a certain length and / or width, so that the same temperature measuring unit 22 can measure different temperatures at different positions, obtain a plurality of isothermal lines with different temperatures, and improve the sensitivity, accuracy and reliability of the thermal conductivity detection. For example, as shown in FIG. 2, in the same temperature measuring unit 22, there are temperature measuring point A, temperature measuring point B and temperature measuring point C. The temperature measured by the temperature measuring point A is higher than the temperature measured by the temperature measuring point B, and the temperature measured by the temperature measuring point B is higher than the temperature measured by the temperature measuring point C. The temperature measuring point A, the temperature measuring point B and the temperature measuring point C are respectively on three different isothermal lines.

[0055] In addition, in some example embodiments, in the same temperature measurement unit 22, at least some of the temperature measurement points can also be located on the same isotherm, which is beneficial to improve the accuracy and precision of the isotherm, and further improve the detection sensitivity, detection accuracy and detection reliability of the thermal conductivity of the gas to be measured. For example, as shown in FIG. 2, in the case of a linear temperature measurement unit 22, there are temperature measurement points D and E in the same temperature measurement unit 22, and the temperatures measured by the temperature measurement points D and E are the same, i.e., the temperature measurement points D and E are located on the same isotherm. For another example, in the case of a temperature measurement unit 22 with a certain width, there can also be temperature measurement points D, E and F in the same temperature measurement unit 22, and the temperatures measured by the temperature measurement points D, E and F are the same, i.e., the temperature measurement points D, E and F are located on the same isotherm.

[0056] Specifically, in some example embodiments, in different temperature measurement units 22, at least two temperature measurement units 22 have at least some of the temperature measurement points located on the same isotherm, i.e., in the plurality of temperature measurement units 22, at least one temperature measurement point in one temperature measurement unit 22 can be located on the same isotherm as at least one temperature measurement point in another temperature measurement unit 22 (the temperatures measured by the two temperature measurement points are the same), which is beneficial to improve the measurement accuracy and reliability of isotherm measurement or temperature field measurement.

[0057] For example, as shown in FIG. 2, the temperature field layer 2 includes two temperature measurement units 22, wherein the temperature measurement point C is located in one temperature measurement unit 22, and the temperature measurement point D is located in another temperature measurement unit 22, and the temperatures measured by the temperature measurement points C and D are the same, i.e., the temperature measurement points C and D are located on the same isotherm, which is beneficial to improve the measurement accuracy of the isotherm and the temperature field.

[0058] For another example, in some example embodiments, the temperature field layer 2 includes three temperature measuring units 22, namely a first temperature measuring unit, a second temperature measuring unit and a third temperature measuring unit, the first temperature measuring unit and the third temperature measuring unit are located on the same side of the constant temperature heat source 21, and the second temperature measuring unit is located on the other side of the constant temperature heat source 21, wherein at least part of the temperature measuring points of the first temperature measuring unit and the second temperature measuring unit are located on the same isotherm, such as temperature measuring point C and temperature measuring point D, at least part of the temperature measuring points of the second temperature measuring unit and the third temperature measuring unit can also be located on the same isotherm, or the temperature measuring points of the second temperature measuring unit and the third temperature measuring unit are located on different isotherms, respectively; optionally, at least part of the temperature measuring points of the third temperature measuring unit can also be located on the same isotherm as at least part of the temperature measuring points of the first temperature measuring unit; preferably, the temperature measuring points of the third temperature measuring unit and the temperature measuring points of the first temperature measuring unit are located on different isotherms, in this way, there is a certain spacing between the third temperature measuring unit and the first temperature measuring unit, which can avoid the adverse effects of the first temperature measuring unit and the third temperature measuring unit on the temperature field distribution, and further improve the measurement accuracy.

[0059] Specifically, in some example embodiments, in the at least partially non-equidistantly arranged temperature measuring units 22, the spacing between at least one temperature measuring unit 22 and the constant temperature heat source 21 is 1 μm to 10 μm, and the spacing between at least another temperature measuring unit 22 and the constant temperature heat source 21 is 2 μm to 50 μm; it can be understood that the spacing between at least one temperature measuring unit 22 and the constant temperature heat source 21 can be any point value in 1 μm to 10 μm, and the spacing between at least another temperature measuring unit 22 and the constant temperature heat source 21 can be any point value in 2 μm to 50 μm; for example, in the at least partially non-equidistantly arranged temperature measuring units 22, the spacing between at least one temperature measuring unit 22 and the constant temperature heat source 21 can be 1 μm, 2 μm, 2.5 μm, 5 μm, 5.5 μm, 7 μm, 10 μm, etc., and the spacing between at least another temperature measuring unit 22 and the constant temperature heat source 21 can be 2 μm, 5 μm, 10 μm, 15 μm, 25 μm, 30 μm, 40 μm, 45 μm, 50 μm, etc.; in this way, the preparation difficulty of the temperature field layer 2 is relatively low, which is beneficial to improve the forming precision of the temperature field layer 2, and more importantly, at least two temperature measuring units 22 can be located in the temperature field formed by the constant temperature heat source 21 in the to-be-measured gas, which greatly improves the effectiveness and accuracy of temperature detection by the temperature measuring unit 22, and is beneficial to improve the measurement effectiveness, measurement accuracy, measurement precision and measurement stability of the temperature field and each isotherm thereof, and is suitable for measuring the thermal conductivity of various to-be-measured gases, which greatly expands the application range of the thermal conductivity gas sensor.

[0060] Specifically, in some exemplary embodiments, in the non-equidistantly arranged at least part of the temperature measuring units 22, the difference between the distance between at least one temperature measuring unit 22 and the constant temperature heat source 21 and the distance between at least another temperature measuring unit 22 and the constant temperature heat source 21 is 1-40 μm; it can be understood that the difference can be any point value in 1-40 μm; for example, in the non-equidistantly arranged at least part of the temperature measuring units 22, the difference between the distance between at least one temperature measuring unit 22 and the constant temperature heat source 21 and the distance between at least another temperature measuring unit 22 and the constant temperature heat source 21 can be 1 μm, 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, etc.; in this way, the temperature data measured by the at least two temperature measuring units 22 respectively has a certain difference, which is beneficial to improve the accuracy of the temperature field and each isothermal line thereof, and further improve the detection sensitivity, detection accuracy and detection reliability of the to-be-detected gas; in addition, the temperature field layer 2 under the distance and the distance difference has a lower preparation difficulty, which is beneficial to improve the forming accuracy of the temperature field layer 2, and further improve the detection sensitivity, detection accuracy and detection reliability of the thermal conductivity gas sensor.

[0061] For example, the temperature field layer 2 includes a first temperature measuring unit and a second temperature measuring unit, the distance between the first temperature measuring unit and the constant temperature heat source 21 is a first distance, the first distance is 1-10 μm, the distance between the second temperature measuring unit and the constant temperature heat source 21 is a second distance, the second distance is 2-50 μm, the difference between the first distance and the second distance is 1-40 μm, and the arrangement distance of the constant temperature heat source 21, the first temperature measuring unit and the second temperature measuring unit in the temperature field layer 2 is moderate, which can enable the non-equidistantly arranged second temperature measuring unit and the second temperature measuring unit to effectively measure the temperature data, and improve the measurement effectiveness, measurement accuracy and measurement reliability of the temperature measurement, the temperature field measurement and each isothermal line thereof.

[0062] Specifically, in some exemplary embodiments, the constant temperature heat source 21 is in a strip structure, and the at least two temperature measuring units 22 and the constant temperature heat source 21 are located in the same plane, and the strip structure of the constant temperature heat source 21 is beneficial to form a temperature field, thereby facilitating the measurement of temperature by the at least two temperature measuring units 22 and the measurement of the number and density of isothermal lines, improving the measurement effectiveness, sensitivity and measurement accuracy of the thermal conductivity gas sensor, and also facilitating the balance between the temperature field and the force field formed by the constant temperature heat source 21, and improving the measurement effectiveness and measurement stability.

[0063] In some example embodiments, the at least two temperature measuring units 22 are in a plate structure, i.e. in a direction perpendicular to the length direction of the strip structure of the constant temperature heat source 21, the temperature measuring unit 22 has a certain width, which can increase the number of isotherms measured by the temperature measuring unit 22, expand the measurement range, and improve the measurement accuracy; in other example embodiments, the at least two temperature measuring units 22 are in a strip structure, which is convenient for measurement.

[0064] In addition, in the case where the temperature measuring unit 22 is in a strip structure, the temperature measuring unit 22 can be arranged parallel or non-parallel to the constant temperature heat source 21; in some example embodiments, the temperature measuring unit 22 is arranged non-parallel to the constant temperature heat source 21, i.e. there is an included angle between the temperature measuring unit 22 and the constant temperature heat source 21, and the included angle is not 0° or 180°; in other example embodiments, at least part of the at least two temperature measuring units 22 are distributed radially asymmetrically around the constant temperature heat source 21; in some preferred embodiments, the temperature measuring unit 22 is arranged parallel to the constant temperature heat source 21, which facilitates the temperature measuring unit 22 to measure different temperature data to obtain the isotherm distribution state in the temperature field.

[0065] Specifically, as shown in FIG. 3, the temperature field layer 2 includes a composite dielectric layer 23 and a patterned metal layer 24, the composite dielectric layer 23 includes mutually connected suspended parts 230 and support parts 231, the support parts 231 are located on the substrate 1, the suspended parts 230 are located in the suspended grooves 11, and the metal layer 24 is located in the suspended parts 230; then, through the connection relationship between the suspended parts 230 and the support parts 231, the suspended part 230 suspended above the suspended groove 11 can be connected with the substrate 1 at the edge of the suspended groove 11, the composite dielectric layer 23 can play a good protection and support role on the metal layer 24, improve the structural stability of the suspended part 230, and be beneficial to improving the measurement stability and reliability in the measurement process.

[0066] The metal layer 24 includes the constant temperature heat source 21 and the at least two temperature measuring units 22, and the metal layer 24 can generate a thermal effect in a powered state; then, a constant current can be passed through the metal layer 24, so that the temperature of the constant temperature heat source 21 is in a constant temperature state; in this embodiment, the constant temperature heat source 21 can use a self-feedback circuit to maintain a constant temperature, and the temperature of the constant temperature heat source 21 is 120℃-450℃; it can be understood that the temperature of the constant temperature heat source 21 can be any point value in 120℃-450℃, which will not be enumerated here, so as to effectively form a temperature field in the gas to be measured around the constant temperature heat source 21.

[0067] In addition, in some example embodiments, the material of the metal layer 24 can include at least one of platinum-tantalum alloy, platinum-nickel alloy, titanium-tungsten alloy, and nickel-chromium alloy, and can also use silicon material, which is not limited in the present application, as long as the material can conduct electricity to produce a thermal effect, which is within the protection scope of the present application.

[0068] Specifically, the thermal conductivity of the composite medium layer 23 is 0.8 W / (m·K) to 1.1 W / (m·K); it can be understood that the thermal conductivity of the composite medium layer 23 can be any point value in 0.8 W / (m·K) to 1.1 W / (m·K), which is not enumerated here; in this way, the thermal conductivity of the composite medium layer 23 is relatively low, which can reduce the heat conduction in the solid as much as possible, the heat loss in the solid is extremely low, and at the same time, the heat is conducted through the to-be-measured gas in the suspended groove 11 as much as possible, which reduces the interference of the composite medium layer 23 on the formed temperature field, and is beneficial to improve the accuracy of the formed temperature field, and further improve the sensitivity, accuracy and reliability of the temperature measurement, temperature field measurement and thermal conductivity detection.

[0069] In some example embodiments, the material of the composite medium layer 23 includes at least one of silicon oxide, aluminum oxide, hafnium oxide, and silicon nitride, which can effectively protect the metal layer 24 and has a low thermal conductivity and little interference with the temperature field.

[0070] In some example embodiments, the thickness of the composite medium layer 23 is 100 nm to 5 μm; it can be understood that the thickness of the composite medium layer 23 can be any point value in 100 nm to 5 μm; for example, the thickness of the composite medium layer 23 can be 100 nm, 500 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm, etc.; in this way, the thickness of the composite medium layer 23 is relatively thin, which can effectively reduce the heat conduction in the composite medium layer 23, reduce the interference of the composite medium layer 23 on the formed temperature field, greatly improve the detection sensitivity, detection accuracy and detection reliability of the thermal conductivity gas sensor, and the composite medium layer 23 can provide good heat bearing capacity and compensation coefficient, improve the durability of the suspended part 230 and the whole thermal conductivity gas sensor, and is also beneficial to improve the measurement stability of the thermal conductivity of the to-be-measured gas in the measurement process; preferably, the thickness of the composite medium layer 23 is 100 nm to 3 μm.

[0071] Specifically, the composite medium layer 23 includes a plurality of medium layers; in some example embodiments, the composite medium layer 23 includes a first medium layer and a second medium layer, wherein the first medium layer is located on the substrate 1, and the metal layer 24 is located between the first medium layer and the second medium layer, so that the metal layer 24 can be embedded in the composite medium layer 23, and the protection effect and support effect are good.

[0072] Specifically, in some example embodiments, the composite dielectric layer 23 comprises a first dielectric layer, a second dielectric layer, and a third dielectric layer, the first dielectric layer is located on the substrate 1, the metal layer 24 is located between the first dielectric layer and the second dielectric layer, and the third dielectric layer is located on the second dielectric layer, which can effectively cover the metal layer 24, prevent the metal layer 24 from being affected by the external environment, and effectively support the metal layer 24, thereby improving the yield of the temperature field layer 2 during preparation and the measurement accuracy and stability during measurement; it should be noted that in the case of a composite dielectric layer 23 comprising multiple dielectric layers, the thermal expansion coefficients of the dielectric materials between the layers are highly compatible, that is, the thermal expansion coefficients of the adjacent two layers of dielectric materials are very small, and even the same dielectric material (thermal expansion coefficient difference is zero) can be used, and the thermal expansion coefficients of the dielectric materials gradually increase or decrease from bottom to top, so as to effectively reduce the interference of the composite dielectric layer 23 with heat conduction, and greatly improve the measurement sensitivity, accuracy and reliability of the thermal conductivity gas sensor to temperature, temperature field and the thermal conductivity of the measured gas.

[0073] Specifically, in some example embodiments, the thickness of the first dielectric layer is 0.5-1.5 μm; it can be understood that the thickness of the first dielectric layer can be any point value in 0.5-1.5 μm; for example, the thickness of the first dielectric layer can be 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.5 μm, etc.

[0074] Specifically, in some example embodiments, the thickness of the second dielectric layer is 0.5-1.5 μm; it can be understood that the thickness of the second dielectric layer can be any point value in 0.5-1.5 μm; for example, the thickness of the second dielectric layer can be 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.2 μm, 1.5 μm, etc.

[0075] Specifically, in some example embodiments, the thickness of the third dielectric layer is 0.1-0.3 μm; it can be understood that the thickness of the third dielectric layer can be any point value in 0.1-0.3 μm; for example, the thickness of the third dielectric layer can be 0.1 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.25 μm, 0.3 μm, etc.

[0076] Specifically, in some example embodiments, the thickness of the metal layer 24 is 200-800 nm; it can be understood that the thickness of the metal layer 24 can be any point value in 200-800 nm; for example, the thickness of the metal layer 24 can be 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 750 nm, 800 nm, etc.

[0077] Thus, the partial metal layer 24 as the constant temperature heat source 21 can effectively generate heat, the partial metal layer 24 as the temperature measuring unit 22 can stably measure temperature, and the thickness of the whole composite dielectric layer 23 is relatively thin, which can effectively reduce the interference of the composite dielectric layer 23 on the process of forming a temperature field by the constant temperature heat source 21, and provide good support and protection for the metal layer 24, greatly improving the detection sensitivity, detection accuracy, detection stability and detection reliability of the thermal conductivity gas sensor.

[0078] Specifically, as shown in FIG. 3, the metal layer 24 further comprises at least one reinforcing structure 240. As shown in FIG. 1, the reinforcing structure 240 is located on the side of the temperature measuring unit 22 away from the constant temperature heat source 21, and the reinforcing structure 240 penetrates the overhanging groove 11 and is connected with the end of the support part 231 located on the side wall of the overhanging groove 11. The reinforcing structure 240 can make the metal layer 24 and the overhanging part 230 located on the overhanging groove 11 reach good mechanical balance, increase the overall structural strength and structural stability of the overhanging part 230, and be beneficial to improve the durability of the overhanging part 230, the temperature field layer 2 and the whole thermal conductivity gas sensor, and improve the measurement stability and measurement reliability in the measurement process.

[0079] In some exemplary embodiments, the reinforcing structure 240 is a bridge type structure, the middle part of the reinforcing structure 240 is arranged in parallel with the constant temperature heat source 21, and both ends of the reinforcing structure 240 extend to the side wall of the overhanging groove 11 in a direction away from the constant temperature heat source 21. Meanwhile, in the direction parallel to the surface of the temperature field layer 2, the reinforcing structure 240 is connected with the support part 231 at one side wall of the overhanging groove 11 and penetrates the overhanging groove 11 from the one side wall of the overhanging groove 11, and the other end is connected with the support part 231 at the other side wall of the overhanging groove 11, which can greatly improve the stress support for the constant temperature heat source 21 and the temperature measuring unit 22, and improve the structural strength and structural stability of the metal layer 24 and the temperature field layer 2.

[0080] In some example embodiments, the metal layer 24 comprises a reinforcing structure 240 located on the side of the temperature measurement unit 22 away from the constant temperature heat source 21; in other example embodiments, the metal layer 24 comprises two reinforcing structures 240, as shown in FIG. 1, the temperature field layer 2 comprises a first temperature measurement unit and a second temperature measurement unit, one of the reinforcing structures 240 is located on the side of the first temperature measurement unit away from the constant temperature heat source 21, and the middle part of the reinforcing structure 240 is spaced apart from the first temperature measurement unit by a distance smaller than the distance between each of the two ends of the reinforcing structure 240 and the first temperature measurement unit, and the other reinforcing structure 240 is located on the side of the second temperature measurement unit away from the constant temperature heat source 21, and the middle part of the other reinforcing structure 240 is spaced apart from the second temperature measurement unit by a distance smaller than the distance between each of the two ends of the reinforcing structure 240 and the second temperature measurement unit, so that the reinforcing structure 240 forms a bridge-shaped support, effectively balances the stress, improves the structural strength and stability of the temperature field layer 2, especially the suspended part 230 of the temperature field layer 2, and further improves the measurement accuracy and stability during the measurement.

[0081] Specifically, as shown in FIGS. 1 and 3, the thermal conductivity gas sensor further comprises a pad 3 located on the support part 231 of the composite medium layer 23, and the pad 3 is electrically connected with the end of the metal layer 24; wherein a window is formed at the edge of the suspended part 230 or the end of the support part 231 located at the side wall of the suspended groove 11, the window penetrates the second medium layer and the third medium layer in a direction perpendicular to the surface of the temperature field layer 2, and exposes the metal layer 24, so that the end of the pad 3 can be electrically connected with the metal layer 24 in the temperature field layer 2 through the window, and the electrical connection has good reliability.

[0082] On the other hand, the present application also provides a preparation method of a thermal conductivity gas sensor, comprising:

[0083] forming a temperature field layer on a substrate with a suspended groove; the temperature field layer is at least partially suspended in the suspended groove, and the temperature field layer comprises a constant temperature heat source and at least two temperature measurement units arranged at intervals; the suspended groove is used to accommodate the gas to be measured, and the spacing between at least part of the temperature measurement units and the constant temperature heat source is arranged in a non-equidistant manner.

[0084] Specifically, in some example embodiments, the forming of the temperature field layer on the substrate with the suspended groove comprises: S1, forming a first initial medium layer on the surface of an initial substrate.

[0085] S2, forming a patterned metal layer on the first initial medium layer.

[0086] S3, forming a second initial medium layer and a third initial medium layer on the metal layer to obtain an initial temperature field layer; the initial temperature field layer comprises the first initial medium layer, the metal layer, the second initial medium layer and the third initial medium layer.

[0087] S4, performing a patterning process on the initial temperature field layer to obtain the temperature field layer; the temperature field layer comprises the constant-temperature heat source and the at least two temperature measuring units arranged at intervals.

[0088] S5, performing wet etching on the initial substrate to remove the substrate material at the bottom of the temperature field layer to form a suspended groove, thereby obtaining the thermal-conductivity gas sensor; the thermal-conductivity gas sensor comprises the substrate with the suspended groove and the temperature field layer at least partially suspended on the suspended groove.

[0089] In the step S1, the first initial medium layer is first grown on the initial substrate, then in the step S2, the initial metal layer is formed by deposition, and then the initial metal layer is patterned to form the metal layer with the constant-temperature heat source, the at least two temperature measuring units and the at least one reinforcing structure; then in the step S3, the second initial medium layer and the third initial medium layer are continuously grown on the metal layer; then in the step S4, the patterning process can adopt the reactive ion etching process, and through the patterning process, the first initial medium layer, the second initial medium layer and the third initial medium layer are collectively patterned to form the initial temperature field layer, that is, the material of the initial temperature field layer is removed on both sides of the constant-temperature heat source and between the at least two temperature measuring units or outside the temperature measuring units to etch the interval space between the constant-temperature heat source, the at least two temperature measuring units and the reinforcing structure; finally, in the step S5, in the process of wet etching the initial substrate, the substrate material below the metal layer in the initial substrate is removed to form the suspended groove, thereby obtaining the thermal-conductivity gas sensor.

[0090] Specifically, in some exemplary embodiments, after the step S4 and before the step S5, the method further comprises:

[0091] depositing a lead metal on the temperature field layer to form a pad.

[0092] In the step S4, the patterning process can also form a window on the end of the metal layer, the window penetrating through the second medium layer and the third medium layer to expose the end of the metal layer, so that the lead metal is in contact with the metal layer to form a good electrical connection.

[0093] On the other hand, as shown in FIG. 4, the present application also provides a gas thermal conductivity detection method based on the thermal-conductivity gas sensor as described above, the method comprising:

[0094] S101, introducing the to-be-tested gas into the suspended groove and obtaining a temperature measurement data set of at least two temperature measuring units in the process of heating by the constant-temperature heat source; the temperature measurement data set comprises temperature information of multiple positions in the suspended groove.

[0095] S103, performing temperature field calculation based on the temperature measurement data set and distance information between the at least two temperature measuring units, to obtain temperature field information of the constant-temperature heat source in the suspended groove; the distance information is used to indicate the distance between the at least two temperature measuring units and the constant-temperature heat source; and the temperature field information is used to indicate the isotherm distribution state of the to-be-tested gas around the constant-temperature heat source.

[0096] S105, performing heat conduction conversion operation based on the temperature field information, to obtain the thermal conductivity of the to-be-tested gas.

[0097] In the S101 step, each temperature measuring unit can measure the temperature of multiple temperature measuring points at the position thereof, and each temperature measuring point is located at a different position of the suspended groove. Thus, the temperature of each temperature measuring point in the temperature measuring unit can be measured by the single temperature measuring unit, to form a set of temperature information. At least two temperature measuring units can obtain two sets of temperature information, i.e., at least two sets of temperature measurement data sets. Then, in the S103 step, the temperature field calculation is performed based on the at least two sets of temperature measurement data sets and the distance between each of the at least two temperature measuring units and the constant-temperature heat source, to obtain the temperature field information at the position of each temperature measuring unit. The temperature field information can indicate the isotherm distribution state at the position corresponding to the temperature measuring unit. For example, 10 isotherms are detected at the position corresponding to the first temperature measuring unit by the temperature field calculation, and 7 isotherms are detected at the position corresponding to the second temperature measuring unit by the temperature field calculation. Then, in the S105 step, the heat conduction conversion operation can be further performed according to the difference between the isotherm distribution states at the positions corresponding to the at least two temperature measuring units, to obtain the thermal conductivity of the to-be-tested gas. The gas thermal conductivity detection method can effectively eliminate the interference of the ambient temperature and does not need temperature compensation, thereby greatly improving the detection sensitivity, detection accuracy and detection reliability of the gas thermal conductivity detection method.

[0098] Specifically, taking a point heat source (i.e., a point constant-temperature heat source) as an example, when the point heat source is heated, the temperature T in the surrounding environment changes with the distance r between the temperature measuring point and the point heat source. In a spherical coordinate system, the change relationship between the two can be described by the following heat conduction equation:

[0099] By integrating the heat conduction equation, the temperature distribution state of the side of the point heat source is obtained:

[0100] Wherein, Q is the intensity of the point heat source, in the gas thermal conductivity detection method, the value of Q can be obtained by the integral of the heat power applied to the constant temperature heat source and time; k is the thermal conductivity of the gas to be measured; C2 is a structure constant, in the case of constant Q value and heat transfer structure of the side of the constant temperature heat source, C2 is a constant value.

[0101] Therefore, the temperature distribution around the point heat source can be approximately represented as inversely proportional to the distance r, that is:

[0102] Therefore, in the case of change of thermal conductivity of the gas to be measured in the suspended groove, the temperature T changed at different distances is inversely proportional to the distance r, while other parameters (such as C2) will be eliminated in the calculation process and do not affect the calculation result, so that the thermal conductivity k can be calculated, the detection accuracy is high, and the environmental interference is not easy.

[0103] Specifically, in the process of integral solution, the heat conduction equation is integrated to obtain the following formula:

[0104] Wherein, C1 is the integral constant.

[0105] Further integrating the above formula, the following formula is obtained:

[0106] In this way, the relationship between temperature T and distance r is obtained.

[0107] Then, the boundary condition is set to determine the integral constant C1; for example, it is assumed that the temperature at a distance r0 from the point heat source is T0, then the relationship between T0 and r0 can be expressed as:

[0108] Wherein, the integral constant C1 can be determined by the intensity Q of the point heat source:

[0109] Therefore, by integrating the heat conduction equation and determining the integral constant, the temperature distribution state of the side of the point heat source can be determined, so as to finally calculate the thermal conductivity of the gas to be measured, which is simple and convenient to calculate, high in sensitivity and good in accuracy.

[0110] In addition, in some example embodiments, in the step S103, by the temperature field information at the positions corresponding to the at least two temperature measuring units, the overall temperature field information formed by the heat conduction of the heat in the to-be-detected gas in the whole plane around the constant-temperature heat source, i.e. the isotherm distribution state in the whole plane, can be further predicted and restored, and the temperature field information can be further output and displayed, so as to improve the intuitiveness of the detection result.

[0111] Specifically, in some example embodiments, the difference circuit including at least one of a resistance bridge and a Wheatstone bridge is used to measure and calculate the temperature field difference at the positions corresponding to the at least two temperature measuring units, i.e. the isotherm line offset between the temperature measuring units at different distances from the constant-temperature heat source, so as to calculate the thermal conductivity of the to-be-detected gas, which can effectively eliminate the interference of the ambient temperature, does not need temperature compensation, has high detection sensitivity and good accuracy.

[0112] The embodiments of the present application are described below in combination with the above technical solutions.

[0113] Embodiment 1

[0114] The thermal conductivity gas sensor of the present embodiment includes a substrate 1 provided with a suspended groove 11 and a temperature field layer 2 partially suspended on the suspended groove 11, the temperature field layer 2 including a constant-temperature heat source 21 and two temperature measuring units 22 arranged at intervals, the distance between the two temperature measuring units 22 and the constant-temperature heat source 21 is arranged in a non-equidistant manner, the constant-temperature heat source 21 is used to emit heat, the suspended groove 11 is used to accommodate the to-be-detected gas and provide the heat generated by the constant-temperature heat source 21 for heat conduction in the to-be-detected gas, and the temperature measuring unit 22 is used to measure the temperature field at the position where the temperature measuring unit 22 is located.

[0115] Specifically, the constant-temperature heat source 21 and the two temperature measuring units 22 are located in the same horizontal plane, which can avoid the influence difference of different environmental conditions in different three-dimensional space directions on the heat conduction, is conducive to improving the accuracy of the measured temperature field and each isotherm line therein, and further is conducive to improving the detection precision, detection stability and detection reliability of the thermal conductivity of the to-be-detected gas, and has simple and convenient arrangement and low cost.

[0116] Specifically, the two temperature measuring units 22 are distributed on the two sides of the constant-temperature heat source 21, which is convenient and low in difficulty, and the temperature measuring units 22 are distributed relatively dispersedly, which is conducive to improving the accuracy of temperature measurement, and can avoid the adverse effects of some temperature measuring units 22 located between the constant-temperature heat source 21 and the remote temperature measuring units 22 on the isotherm line distribution of the constant-temperature heat source 21 in the to-be-detected gas and on the temperature detection of the remote temperature measuring units 22, and is conducive to further improving the measurement sensitivity, measurement accuracy and measurement reliability of the overall temperature and temperature field, and further improving the measurement accuracy and measurement reliability of the thermal conductivity of the to-be-detected gas.

[0117] Specifically, the temperature measuring unit 22 includes a plurality of temperature measuring points, at least part of the plurality of temperature measuring points in the same temperature measuring unit 22 are located on the same isothermal line in the same plane, and at least part of the plurality of temperature measuring points can also be located on the same isothermal line in the same plane; in different temperature measuring units 22, at least part of the temperature measuring points of at least two temperature measuring units 22 are located on the same isothermal line, which is beneficial to improve the measurement sensitivity, measurement accuracy, measurement precision and measurement reliability of isothermal line measurement or temperature field measurement.

[0118] Specifically, the two temperature measuring units 22 include a first temperature measuring unit and a second temperature measuring unit, the distance between the first temperature measuring unit and the constant temperature heat source 21 is 10 μm, and the distance between the second temperature measuring unit and the constant temperature heat source 21 is 50 μm, which is relatively low in preparation difficulty, and is beneficial to improve the forming precision of the temperature field layer 2. More importantly, the constant temperature heat source 21 forms a temperature field in the heat conduction of the to-be-measured gas, and both of the two temperature measuring units 22 can be located in the temperature field, which greatly improves the effectiveness and accuracy of temperature detection by the temperature measuring unit 22, and is beneficial to improve the measurement effectiveness, measurement accuracy, measurement precision and measurement stability of the temperature field and each isothermal line thereof, and is suitable for measuring the thermal conductivity of various to-be-measured gases, which greatly expands the application range of the thermal conductivity gas sensor.

[0119] Specifically, the constant temperature heat source 21 is in a strip structure, which is convenient for forming a temperature field, thereby being beneficial to the measurement of temperature by the two temperature measuring units 22 and the measurement of the number and density of isothermal lines, improving the measurement effectiveness, sensitivity and measurement precision of the thermal conductivity gas sensor, and also being convenient for controlling the balance of the temperature field and the force field formed by the constant temperature heat source 21, which is beneficial to improve the measurement effectiveness and measurement stability.

[0120] Specifically, the temperature measuring unit 22 can be arranged in parallel with the constant temperature heat source 21, which is convenient for the temperature measuring unit 22 to measure different temperature data to obtain the isothermal line distribution state in the temperature field.

[0121] Specifically, as shown in FIG. 3, the temperature field layer 2 includes a composite dielectric layer 23 and a patterned metal layer 24, the composite dielectric layer 23 includes a suspended part 230 and a support part 231 connected to each other, the support part 231 is located on the substrate 1, the suspended part 230 is located in the suspended groove 11, and the metal layer 24 is located in the suspended part 230. Then, through the connection relationship between the suspended part 230 and the support part 231, the suspended part 230 suspended above the suspended groove 11 can be connected with the substrate 1 at the edge of the suspended groove 11, and the composite dielectric layer 23 can play a good protection and support role on the metal layer 24, improve the structural stability of the suspended part 230, and be beneficial to improve the measurement stability and measurement reliability in the measurement process.

[0122] The metal layer 24 includes the constant temperature heat source 21 and the two temperature measuring units 22, and can generate a thermal effect in an energized state, and a self-feedback circuit is used to maintain the temperature of the constant temperature heat source 21 constant, and the temperature of the constant temperature heat source 21 is 300 DEG C, so as to effectively form a temperature field in the gas to be measured around the constant temperature heat source 21.

[0123] Specifically, the composite dielectric layer 23 includes a first dielectric layer, a second dielectric layer and a third dielectric layer, the first dielectric layer is located on the substrate 1, the metal layer 24 is located between the first dielectric layer and the second dielectric layer, and the third dielectric layer is located on the second dielectric layer, wherein the thickness of the first dielectric layer is 0.5 microns, the thickness of the second dielectric layer is 0.5 microns, the thickness of the third dielectric layer is 0.1 microns, and the thickness of the metal layer 24 is 200 nm, the composite dielectric layer 23 can effectively cover the metal layer 24, prevent the metal layer 24 from being affected by the external environment, and effectively support the metal layer 24, which is conducive to improving the yield of the temperature field layer 2 in the preparation process and the measurement accuracy and measurement stability in the measurement process.

[0124] Specifically, as shown in FIG. 3, the metal layer 24 further includes two reinforcing structures 240, as shown in FIG. 1, the reinforcing structure 240 is located on the side of the temperature measuring unit 22 away from the constant temperature heat source 21, the reinforcing structure 240 penetrates the overhanging groove 11 and is connected with the end of the support part 231 located on the side wall of the overhanging groove 11, the reinforcing structure 240 can make the metal layer 24 and the overhanging part 230 located on the overhanging groove 11 reach a good mechanical balance, increase the overall structural strength and structural stability of the overhanging part 230, and be conducive to improving the durability of the overhanging part 230, the temperature field layer 2 and the thermal conductivity gas sensor, and improving the measurement stability and measurement reliability in the measurement process.

[0125] The reinforcing structure 240 is a bridge type structure, the middle part of the reinforcing structure 240 is arranged in parallel with the constant temperature heat source 21, and the two ends of the reinforcing structure 240 extend to the side wall of the overhanging groove 11 in a direction away from the constant temperature heat source 21, and in a direction parallel to the surface of the temperature field layer 2, the reinforcing structure 240 is connected with the support part 231 at one side wall of the overhanging groove 11 and penetrates the overhanging groove 11 from the one side wall of the overhanging groove 11, and the other end is connected with the support part 231 at the other side wall of the overhanging groove 11, which can greatly improve the stress support for the constant temperature heat source 21 and the temperature measuring unit 22, and improve the structural strength and structural stability of the metal layer 24 and the temperature field layer 2.

[0126] Specifically, as shown in FIG. 1 and FIG. 3, the thermal conductive gas sensor further comprises a pad 3, which is located on the support part 231 of the composite medium layer 23 and is electrically connected with the end of the metal layer 24; wherein a window is opened at the edge of the overhanging part 230 or the end of the support part 231 located at the side wall of the overhanging groove 11, the window penetrates the second medium layer and the third medium layer in the direction perpendicular to the surface of the temperature field layer 2, and exposes the metal layer 24, so that the end of the pad 3 can be electrically connected with the metal layer 24 in the temperature field layer 2 through the window, and the electrical connection has good reliability.

[0127] Embodiment 2

[0128] The difference between this embodiment and embodiment 1 is that the distance between the first temperature measuring unit and the constant temperature heat source 21 is 5 μm, and the distance between the second temperature measuring unit and the constant temperature heat source 21 is 25 μm, so that the number of isotherms measured by the first temperature measuring unit and the second temperature measuring unit is larger, which is beneficial to improve the detection accuracy and detection reliability; the rest is the same as embodiment 1.

[0129] Embodiment 3

[0130] The difference between this embodiment and embodiment 1 is that the temperature field layer 2 comprises three temperature measuring units 22, the three temperature measuring units 22 comprising a first temperature measuring unit, a second temperature measuring unit and a third temperature measuring unit, the first temperature measuring unit being located between the third temperature measuring unit and the constant temperature heat source 21, and the distance between the third temperature measuring unit and the constant temperature heat source 21 being greater than the distance between the second temperature measuring unit and the constant temperature heat source 21, which is beneficial to further expand the temperature field measurement range and improve the measurement sensitivity, measurement accuracy and measurement reliability; the rest is the same as embodiment 1.

[0131] It should be noted that each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same and similar parts between each embodiment can be referred to.

[0132] The above only describes some embodiments of the present application and is not used to limit the present application. It should be understood by those skilled in the art that the present application can have various changes and improvements, and any modification, equivalent replacement and improvement made according to the present application all fall within the scope of protection claimed by the present application.

Claims

A thermal conductivity gas sensor characterized by The thermal field layer includes a constant-temperature heat source and at least two temperature measuring units which are arranged at intervals. The thermal conductivity gas sensor according to claim 1, wherein The constant-temperature heat source and the at least two temperature measuring units are located in the same plane. The thermal conductivity gas sensor according to claim 1, wherein The temperature measuring unit includes a plurality of temperature measuring points, and at least some of the temperature measuring points in the same temperature measuring unit are located on a plurality of isotherms in the same plane. The thermal conductivity gas sensor according to claim 1, wherein The at least two temperature measuring units are located on the same side of the constant-temperature heat source; or The at least two temperature measuring units are distributed on both sides of the constant-temperature heat source. The thermal conductivity gas sensor according to any one of claims 1 to 4, characterized in that The thermal field layer satisfies at least one of the following characteristics: In the at least some of the temperature measuring units arranged at intervals, the distance between at least one of the temperature measuring units and the constant-temperature heat source is 1-10 μm, and the distance between at least another of the temperature measuring units and the constant-temperature heat source is 2-50 μm. In the at least some of the temperature measuring units arranged at intervals, the difference between the distance between at least one of the temperature measuring units and the constant-temperature heat source and the distance between at least another of the temperature measuring units and the constant-temperature heat source is 1-40 μm. The thermal conductivity gas sensor according to any one of claims 1 to 4, characterized in that The constant-temperature heat source and the at least two temperature measuring units are in strip-shaped structures, and the at least two temperature measuring units and the constant-temperature heat source are located in the same plane and arranged in parallel. The thermal conductivity gas sensor according to any one of claims 1 to 4, characterized in that The thermal field layer includes a composite dielectric layer and a patterned metal layer, the composite dielectric layer includes suspended parts and support parts connected to each other, the support parts are located on the substrate, the suspended parts are located in the suspended groove, the metal layer is located in the suspended parts, and the metal layer includes the constant-temperature heat source and the at least two temperature measuring units. The thermal conductivity gas sensor according to claim 7, characterized in that The composite dielectric layer includes a first dielectric layer, a second dielectric layer and a third dielectric layer, the first dielectric layer is located on the substrate, the metal layer is located between the first dielectric layer and the second dielectric layer, and the third dielectric layer is located on the second dielectric layer; and the thermal field layer satisfies at least one of the following characteristics: The thickness of the first dielectric layer is 0.5-1.5 μm. The thickness of the second dielectric layer is 0.5-1.5 μm. The thickness of the third dielectric layer is 0.1-0.3 μm. The thickness of the metal layer is 200-800 nm. The metal layer further includes at least one reinforcing structure, the reinforcing structure is located on the side of the temperature measuring unit away from the constant-temperature heat source, the reinforcing structure penetrates the suspended groove and is connected to the end of the support part located on the side wall of the suspended groove. The thermal conductivity gas sensor according to claim 7, characterized in that The thermal conduction gas sensor further includes a pad, the pad is located on the support part of the composite dielectric layer, and the pad is electrically connected to the end of the metal layer. The thermal conductivity gas sensor according to claim 7, characterized in that The thermal field layer includes A method of manufacturing a thermal conductivity gas sensor, characterized by ​ Forming a temperature field layer on a substrate with a suspended groove; the temperature field layer is at least partially suspended on the suspended groove, and the temperature field layer comprises a constant temperature heat source and at least two temperature measuring units arranged at intervals; the suspended groove is used to accommodate a gas to be measured, and the intervals between at least some of the at least two temperature measuring units and the constant temperature heat source are arranged non-equidistantly. The method of claim 11, wherein the thermal conductivity gas sensor is prepared by a method comprising: The forming of the temperature field layer on the substrate with the suspended groove comprises: forming a first initial medium layer on the surface of an initial substrate; forming a patterned metal layer on the first initial medium layer; forming a second initial medium layer and a third initial medium layer on the metal layer to obtain an initial temperature field layer; the initial temperature field layer comprises the first initial medium layer, the metal layer, the second initial medium layer, and the third initial medium layer; performing a patterning process on the initial temperature field layer to obtain the temperature field layer; the temperature field layer comprises the constant temperature heat source and the at least two temperature measuring units arranged at intervals; performing wet etching on the initial substrate to remove the substrate material at the bottom of the temperature field layer to form a suspended groove, thereby obtaining a thermal conductivity gas sensor; the thermal conductivity gas sensor comprises the substrate with the suspended groove and the temperature field layer at least partially suspended on the suspended groove. A gas thermal conductivity detection method, characterized in that, Detecting based on the thermal conductivity gas sensor according to any one of claims 1-10, the method comprising: passing the gas to be measured into the suspended groove and obtaining a temperature measurement data set of the at least two temperature measuring units during the heating of the constant temperature heat source; the temperature measurement data set comprises temperature information of multiple positions in the suspended groove; performing temperature field calculation based on the temperature measurement data set and distance information between the at least two temperature measuring units, thereby obtaining temperature field information of the constant temperature heat source in the suspended groove; the distance information is used to indicate the intervals between the at least two temperature measuring units and the constant temperature heat source; the temperature field information is used to indicate the isotherm distribution state of the gas to be measured around the constant temperature heat source; performing thermal conductivity conversion calculation based on the temperature field information, thereby obtaining the thermal conductivity of the gas to be measured.

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