阅读说明：本技术 多维度多参量气体传感器及其制备方法、气体检测方法 (Multi-dimensional multi-parameter gas sensor, preparation method thereof and gas detection method ) 是由 李娜 安飞 孙冰 王林 张树才 徐伟 胡适 梁文杰 于 2020-04-10 设计创作，主要内容包括：本发明涉及气体传感器技术领域,公开了一种多维度多参量气体传感器及其制备方法。所述气体传感器包括：传感结构,用于针对多种气体产生对应的多路电信号；微加热结构,用于对所述传感结构提供不同的加热温度；信号检测系统,用于获取所述传感结构产生的多路电信号,根据所述电信号的变化情况确定所述电信号对应的气体的类别和浓度。本发明基于气体敏感材料的选择性、广谱性响应以及温度特征,在单个气体传感器上结合多种气敏传感材料实现复杂气氛检测,缩小整体器件的体积,提高集成度。(The invention relates to the technical field of gas sensors, and discloses a multi-dimensional multi-parameter gas sensor and a preparation method thereof. The gas sensor includes: the sensing structure is used for generating corresponding multi-channel electric signals aiming at various gases; a micro-heating structure for providing different heating temperatures to the sensing structure; and the signal detection system is used for acquiring a plurality of paths of electric signals generated by the sensing structure and determining the category and the concentration of the gas corresponding to the electric signals according to the change condition of the electric signals. The invention realizes complex atmosphere detection by combining multiple gas-sensitive sensing materials on a single gas sensor based on the selectivity, broad-spectrum response and temperature characteristics of the gas-sensitive materials, reduces the volume of the whole device and improves the integration level.)

1. A multi-dimensional, multi-parametric gas sensor, comprising:

the sensing structure is used for generating corresponding multi-channel electric signals aiming at various gases;

a micro-heating structure for providing different heating temperatures to the sensing structure;

and the signal detection system is used for acquiring a plurality of paths of electric signals generated by the sensing structure and determining the category and the concentration of the gas corresponding to the electric signals according to the change condition of the electric signals.

2. The multidimensional multiparameter gas sensor of claim 1, wherein the sensing structure comprises a plurality of measurement electrodes and gas-sensitive films coated on the measurement electrodes, the gas-sensitive films coated on the measurement electrodes being of different materials.

3. The multi-dimensional multi-parameter gas sensor according to claim 2, wherein the micro-heating structure comprises a silicon-based substrate and a heating layer disposed on the silicon-based substrate, the heating layer is divided into a plurality of heating zones with different temperatures, and the plurality of measuring electrodes are disposed in the corresponding heating zones respectively.

4. The multi-dimensional multi-parameter gas sensor according to claim 3, wherein the heating layer comprises a heating electrode, the heating electrode is a plurality of heating resistance wires with different cross-sectional areas, and the plurality of heating resistance wires form a plurality of heating zones.

5. The multi-dimensional multi-parameter gas sensor according to claim 4, wherein the heating resistance wire has a cross-sectional thickness of 300nm to 500nm, a cross-sectional width of 10 μm to 100 μm, and a length of 1.5mm to 20 mm.

6. The multi-dimensional multi-parameter gas sensor according to claim 5, wherein a plurality of the heating resistance wires are arranged at intervals; the distance between two adjacent heating resistance wires is 2-5 times of the section width of the heating resistance wires.

7. The multi-dimensional multi-parameter gas sensor according to claim 4, wherein each heating resistance wire is connected end to end in a ring shape, and the plurality of heating resistance wires are distributed in a gradient manner on the silicon-based substrate.

8. The multi-dimensional multi-parametric gas sensor of claim 3, wherein the heating layer comprises a heating electrode that is a resistance heater wire having a plurality of segments of different cross-sectional areas, the plurality of segments of resistance heater wire forming a plurality of the heating zones.

9. The multi-dimensional multi-parameter gas sensor as claimed In claim 2, wherein the gas sensitive film is made of metal oxide nano gas sensitive material, and the metal oxide nano gas sensitive material is SnO2, WO3, In₂O₃NiO, MoO3 and CuO.

10. The multi-dimensional multi-parameter gas sensor of claim 3, wherein the heating layer comprises a heating electrode, the heating electrode is distributed in the center of the heating layer, and a plurality of measuring electrodes are distributed around the heating electrode.

11. The multi-dimensional multi-parameter gas sensor of claim 10, wherein the heating layer has a geometric length 1-6 times longer than that of the region where the heating electrode is disposed, and the geometric length of the heating layer is between 500 μm and 3000 μm.

12. The multidimensional multiparameter gas sensor according to claim 11, wherein the heater electrode is surrounded by a heater resistance wire; the thickness of the heating resistance wire is 300nm-500nm, the width is 10 μm-100 μm, and the length is 1.5mm-13 mm; the distance between the two surrounding sections of the heating resistance wire is less than twice of the width of the heating resistance wire.

13. A multi-dimensional, multi-parametric gas sensor as in claim 3, wherein the signal detection system comprises a signal detection module and a signal processing module;

the signal detection module is used for acquiring a plurality of paths of electric signals generated by the measuring electrode and measuring a resistance value corresponding to the electric signals;

the signal processing module is used for determining the category and the concentration of the gas corresponding to the electric signal according to the change situation of the resistance value corresponding to the electric signal.

14. The multi-dimensional multi-parameter gas sensor according to claim 13, wherein the signal detection module comprises an analog switch circuit, a driving circuit and an analog-to-digital conversion circuit connected in sequence;

the analog switch circuit is connected with the measuring electrode and is used for acquiring a plurality of paths of electric signals generated by the measuring electrode, and the plurality of paths of electric signals are analog electric signals;

the analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal.

15. The multi-dimensional multi-parametric gas sensor of claim 13, wherein the signal processing module comprises:

and the singlechip is used for determining the type and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal and outputting a type signal and a concentration signal of the gas.

16. The multi-dimensional, multi-parametric gas sensor of claim 15, wherein the signal detection system further comprises:

and the alarm module is connected with the singlechip and used for receiving the category signal and the concentration signal of the gas and generating an alarm signal when the concentration signal of the gas exceeds a preset threshold value of the gas concentration.

17. The multi-dimensional, multi-parametric gas sensor of claim 15, wherein the signal detection system further comprises:

and the wireless communication module is connected with the singlechip and is used for wirelessly transmitting the category signal and the concentration signal of the gas.

18. A preparation method of a multi-dimensional multi-parameter gas sensor is characterized by comprising the following steps:

s1) manufacturing a heating layer on the silicon-based substrate to form a micro-heating structure;

s2) manufacturing a plurality of measuring electrodes on the micro heating structure, and coating a corresponding gas sensitive film on the surface of each measuring electrode to form a sensing structure;

s3) manufacturing the micro heating structure and the sensing structure into a micro sensing chip;

s4) the circuit board integrated with the signal detection system and the micro sensing chip are packaged into a whole.

19. The method for manufacturing a multi-dimensional multi-parameter gas sensor according to claim 18, wherein step S1) is to fabricate a heating layer on a silicon-based substrate, comprising:

and manufacturing a plurality of heating resistance wires with different sectional areas or a heating resistance wire with a plurality of sections with different sectional areas on the silicon-based substrate to form a plurality of heating zones with different temperatures.

20. The method for preparing a multidimensional multiparameter gas sensor according to claim 19, wherein step S2) comprises fabricating a plurality of measuring electrodes on the micro-heating structure, and coating a corresponding gas sensitive film on each measuring electrode surface, comprising:

and manufacturing measuring electrodes in the heating zones with different temperatures, and coating a gas sensitive film matched with the heating temperature of the heating zone where the measuring electrode is positioned on the surface of each measuring electrode.

21. A method of gas detection, wherein a gas is detected using a multi-dimensional, multi-parameter gas sensor according to any of claims 1-17.

22. The method of claim 21, comprising detecting a gas mixture of two or more gases.

Technical Field

The invention relates to the technical field of gas sensors, in particular to a multi-dimensional multi-parameter gas sensor, a preparation method of the multi-dimensional multi-parameter gas sensor and a gas detection method.

Background

The gas sensor based on the metal oxide semiconductor sensing principle can be used for detecting toxic gas with the ppb level or flammable and explosive gas with the percentage concentration, and is widely applied. The principle of the gas sensor is that parameters such as gas components and concentration are converted into resistance variation and then converted into output signals of current and voltage, so that the detection function is realized. In particular, a gas-sensitive resistor material such as Metal-Oxide-Semiconductor (MOS) is made of impurity defects with deviated stoichiometric ratio, and some precious metals are doped or loaded when the gas-sensitive material is synthesized, so as to improve the selectivity or sensitivity of a certain material to certain gas components. MOS materials are classified into P-type semiconductors and N-type semiconductors, for example, P-type semiconductors such as NiO and PbO, and N-type semiconductors such as SnO2, WO3, Fe2O3, and In2O 3. Metal oxides are insulators at room temperature and exhibit gas-sensitive properties after processing into Metal Oxide Semiconductors (MOS). When the MOS material contacts with the gas to be measured, the resistivity of the MOS material is obviously changed due to the gas adsorbed on the surface of the MOS material, and the resistivity is restored to the initial state after desorption. The adsorption of the MOS material to the gas can be divided into physical adsorption and chemical adsorption, and the adsorption is mainly physical adsorption at normal temperature, namely the gas and the molecules on the surface of the MOS material are adsorbed, and no electron exchange exists between the gas and the molecules, so that no chemical bond is formed. The chemical adsorption means that ion adsorption is established between gas and the surface of the MOS material, and electrons are exchanged between the gas and the MOS material, so that chemical bonding force exists. If the MOS material is heated to raise its temperature, chemisorption increases and reaches a maximum at a certain temperature. If the MOS material exhibits a desorption state at a temperature higher than a certain value, the physical adsorption and the chemical adsorption are simultaneously reduced. For example, tin oxide (SnO2), which is the most common MOS material, adsorbs a certain gas at normal temperature, and the resistivity does not change much, and in this case, the MOS material is physisorption; if the gas concentration is kept unchanged, the MOS material is heated, the conductivity of the MOS material is obviously increased along with the rise of the temperature, and the conductivity changes greatly particularly within the temperature range of 100-500 ℃. Therefore, the temperature required by the gas sensor made of MOS material is much higher than the room temperature, and different MOS materials detect different gas components and the temperature at which the concentration needs to be changeable.

The types of the mixed gas in the scene of the complex atmosphere environment may be more than ten, and if the complex atmosphere detection is to be realized, a sensing device capable of detecting multiple gases simultaneously is required. At present, a sensor device for detecting complex atmosphere generally adopts a plurality of same micro-heating chip units to be independently arranged to form a sensor array, and the plurality of micro-heating chip units respectively heat corresponding gas-sensitive sensing materials so as to realize complex atmosphere detection function. Because each micro-heating chip of the sensor array needs to be heated independently, and a plurality of micro-heating chips need to be heated in a plurality of heating structures, the integral integration level of the device is not high, and the advantages of small volume and low energy consumption of the semiconductor gas sensing device cannot be embodied. The micro-heating chip of the gas sensor has single heating temperature, one micro-heating chip correspondingly heats one gas-sensitive sensing material, cross detection can not be realized on a single chip by combining multiple MOS sensing materials at different temperatures, and the detection accuracy under a complex atmosphere environment is low.

Disclosure of Invention

The invention aims to provide a multi-dimensional multi-parameter gas sensor and a preparation method thereof, so as to realize complex atmosphere detection by combining multiple gas-sensitive sensing materials on a single gas sensor and improve the integration level of the gas sensor.

In order to achieve the above object, a first aspect of the present invention provides a multidimensional multiparameter gas sensor comprising:

the sensing structure is used for generating corresponding multi-channel electric signals aiming at various gases;

a micro-heating structure for providing different heating temperatures to the sensing structure;

and the signal detection system is used for acquiring a plurality of paths of electric signals generated by the sensing structure and determining the category and the concentration of the gas corresponding to the electric signals according to the change condition of the electric signals.

Further, the sensing structure comprises a plurality of measuring electrodes and gas sensitive films coated on the measuring electrodes, and the materials of the gas sensitive films coated on the measuring electrodes are different.

Further, the micro-heating structure comprises a silicon-based substrate and a heating layer arranged on the silicon-based substrate, wherein the heating layer is divided into a plurality of heating zones with different temperatures, and the plurality of measuring electrodes are respectively arranged in the corresponding heating zones.

Further, the heating layer comprises a heating electrode, the heating electrode is a plurality of heating resistance wires with different sectional areas, and the plurality of heating resistance wires form a plurality of heating areas.

Furthermore, the thickness of the section of the heating resistance wire is 300nm-500nm, the width of the section is 10 μm-100 μm, and the length is 1.5mm-20 mm.

Furthermore, the heating resistance wires are arranged at intervals; the distance between two adjacent heating resistance wires is 2-5 times of the section width of the heating resistance wires.

Furthermore, each heating resistance wire is respectively connected end to form a ring shape, and the plurality of heating resistance wires are distributed on the silicon-based substrate in a gradient manner.

Further, the heating layer comprises a heating electrode, the heating electrode is a heating resistance wire with a plurality of sections with different sectional areas, and the plurality of sections of the heating resistance wire form a plurality of heating areas.

Further, the gas sensitive film is made of metal oxide nano gas sensitive materials, and the metal oxide nano gas sensitive materials are SnO2, WO3 and In₂O₃NiO, MoO3 and CuO.

Further, the zone of heating includes heating electrode, heating electrode distributes in the center of zone of heating, and is a plurality of measuring electrode distributes in heating electrode's periphery.

Further, the geometric length of the heating layer is 1-6 times of that of the region where the heating electrode is distributed, and the geometric length of the heating layer is 500-3000 μm.

Furthermore, the heating electrode is formed by winding a heating resistance wire; the thickness of the heating resistance wire is 300nm-500nm, the width is 10 μm-100 μm, and the length is 1.5mm-13 mm; the distance between the two surrounding sections of the heating resistance wire is less than twice of the width of the heating resistance wire.

Further, the signal detection system comprises a signal detection module and a signal processing module;

the signal detection module is used for acquiring a plurality of paths of electric signals generated by the measuring electrode and measuring a resistance value corresponding to the electric signals;

the signal processing module is used for determining the category and the concentration of the gas corresponding to the electric signal according to the change situation of the resistance value corresponding to the electric signal.

Furthermore, the signal detection module comprises an analog switch circuit, a driving circuit and an analog-to-digital conversion circuit which are connected in sequence;

the analog switch circuit is connected with the measuring electrode and is used for acquiring a plurality of paths of electric signals generated by the measuring electrode, and the plurality of paths of electric signals are analog electric signals;

the analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal.

Further, the signal processing module includes:

and the singlechip is used for determining the type and the concentration of the gas corresponding to the electric signal according to the change condition of the resistance value corresponding to the electric signal and outputting a type signal and a concentration signal of the gas.

Further, the signal detection system further includes:

and the alarm module is connected with the singlechip and used for receiving the category signal and the concentration signal of the gas and generating an alarm signal when the concentration signal of the gas exceeds a preset threshold value of the gas concentration.

Further, the signal detection system further includes:

and the wireless communication module is connected with the singlechip and is used for wirelessly transmitting the category signal and the concentration signal of the gas.

In a second aspect, the present invention provides a method for preparing a multidimensional multiparameter gas sensor, comprising the steps of:

s1) manufacturing a heating layer on the silicon-based substrate to form a micro-heating structure;

s2) manufacturing a plurality of measuring electrodes on the micro heating structure, and coating a corresponding gas sensitive film on the surface of each measuring electrode to form a sensing structure;

s3) manufacturing the micro heating structure and the sensing structure into a micro sensing chip;

s4) the circuit board integrated with the signal detection system and the micro sensing chip are packaged into a whole.

Further, step S1) of fabricating a heating layer on the silicon-based substrate includes:

and manufacturing a plurality of heating resistance wires with different sectional areas or a heating resistance wire with a plurality of sections with different sectional areas on the silicon-based substrate to form a plurality of heating zones with different temperatures.

Further, step S2) is to fabricate a plurality of measuring electrodes on the micro-heating structure, and coat a corresponding gas sensitive film on the surface of each measuring electrode, including:

and manufacturing measuring electrodes in the heating zones with different temperatures, and coating a gas sensitive film matched with the heating temperature of the heating zone where the measuring electrode is positioned on the surface of each measuring electrode.

In a third aspect, the invention provides a gas detection method, which uses the above-mentioned multi-dimensional multi-parameter gas sensor to detect gas.

Further, the method comprises the step of detecting the mixed gas composed of more than two gases.

The gas sensor provided by the invention realizes the concentration detection of multi-parameter gas based on three dimensions of selectivity, broad-spectrum response and temperature characteristics of gas sensitive materials. The method comprises the steps of screening a plurality of gas-sensitive sensing materials which respond to specific gas according to selectivity of the gas-sensitive materials to form a sensing structure, designing a corresponding micro-heating structure according to the broad-spectrum response of the gas-sensitive sensing materials, providing different heating temperatures for the sensing structure through the micro-heating structure, and determining the concentrations of a plurality of target gases through a signal detection system according to the signal change condition generated by the sensing structure. The invention realizes complex atmosphere detection by combining multiple gas-sensitive sensing materials on a single gas sensor based on the selectivity, broad-spectrum response and temperature characteristics of the gas-sensitive materials, reduces the volume of the whole device and improves the integration level.

Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:

FIG. 1 is a schematic diagram of a multi-dimensional multi-parameter gas sensor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor according to a second embodiment of the present invention;

fig. 4 is a temperature distribution simulation diagram of a heating layer of the multi-dimensional multi-parameter gas sensor according to the second embodiment of the present invention;

FIG. 5 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor provided in the third embodiment of the present invention; fig. 6 is a schematic view illustrating the geometric parameter definition of a micro-heating structure according to a third embodiment of the present invention;

FIG. 7 is a graph of the ratio m/h of the geometric length of the heating layer to the geometric length of the region where the heating electrodes are disposed, as a function of power, according to a third embodiment of the present invention;

FIG. 8 is a graph of the ratio m/h of the geometric length of the heating layer to the geometric length of the region where the heating electrodes are disposed, as a function of thermal uniformity, according to a third embodiment of the present invention;

fig. 9 is a simulation diagram of temperature distribution of a heating layer of the multi-dimensional multi-parameter gas sensor according to the third embodiment of the present invention;

FIG. 10 is a block diagram of a signal detection system of a multi-dimensional multi-parameter gas sensor according to a fourth embodiment of the present invention;

fig. 11 is a block diagram of a signal detection module of the signal detection system according to the fourth embodiment of the present invention;

fig. 12 is a schematic diagram of an analog switch circuit of a signal detection module according to a fourth embodiment of the present invention;

fig. 13 is a schematic diagram of a driving circuit of a signal detection module according to a fourth embodiment of the present invention;

fig. 14 is a schematic diagram of an analog-to-digital conversion circuit of a signal detection module according to a fourth embodiment of the present invention;

fig. 15 is a schematic circuit diagram of a signal processing module of a signal detection system according to a fourth embodiment of the present invention;

fig. 16 is a flowchart of a method for manufacturing a multidimensional multiparameter gas sensor according to a fifth embodiment of the present invention.

Description of the reference numerals

10-silicon-based substrate, 20-heating layer, 21-heating electrode, 22-measuring electrode,

23-heating electrode pads, 24-measuring electrode pads, 25-heating electrode leads, 30-sensing structures,

201-first heating zone, 202-second heating zone, 203-third heating zone,

211-a first heating resistance wire, 212-a second heating resistance wire, 213-a third heating resistance wire,

21 a-a first segment resistance wire, 21 b-a second segment resistance wire, and 21 c-a third segment resistance wire.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Fig. 1 is a schematic structural diagram of a multi-dimensional multi-parameter gas sensor provided by an embodiment of the invention. The dimensional multi-parameter gas sensor provided by the embodiment of the invention comprises a sensing structure, a micro heating structure and a signal detection system. The sensing structure is used for generating corresponding multi-channel electric signals aiming at various gases; the micro heating structure is used for providing different heating temperatures for the sensing structure; the signal detection system is used for acquiring a plurality of paths of electric signals generated by the sensing structure and determining the category and the concentration of the gas corresponding to the electric signals according to the change condition of the electric signals.

As shown in fig. 1, the micro heating structure includes a silicon-based substrate 10 and a heating layer 20 disposed on the silicon-based substrate 10, wherein the heating layer 20 is divided into a plurality of heating zones of different temperatures. The sensing structure 30 includes a plurality of measuring electrodes and a gas sensitive film coated on the measuring electrodes, the material of the gas sensitive film coated on the measuring electrodes is different, the measuring electrodes are respectively disposed in corresponding heating zones, and the response temperature of the gas sensitive film coated on the surface of each measuring electrode is matched with the heating temperature of the heating zone where the measuring electrode is located.

The gas sensitive film is made of metal oxide nano gas sensitive materials such as SnO2, WO3, In2O3, NiO, MoO3 and CuO. The selectivity is a key index of the broad-spectrum gas sensitive material, materials with different response characteristics are preferably selected by a method for quantifying the selectivity of the gas sensitive metal oxide sensing material to various gases, and specificity and broad-spectrum classification are carried out, so that the sensor can selectively distinguish target gases from complex gas mixtures, and multi-parameter quantitative identification is realized.

The selectivity of the gas sensitive material to a single gas is closely related to selective adsorption, surface chemical reaction and oxide energy band structure and reaction temperature, a suitable sensing material is optimized based on the selectivity of the gas sensitive material, the difference of the sensitivity of the gas sensitive material to different gases is represented according to the selectivity, and the functional relation between the selectivity and the sensitivity is determined. For example, S represents the sensitivity of a gas-sensitive material to gas x at a certain concentration, ∑ S_xRepresenting the sum of the sensitivities of all reference gases at the same concentration, defining the selectivity of the sensor to gas x as SL_x＝(S_x/∑S_x) 100%. SL if selectivity of a gas sensitive material_xThe gas-sensitive material has a specific response attribute to gas x and is suitable for acquiring a characteristic value in a sensor; SL if the selectivity is 20% ≦ SL_xLess than 60 percent, which indicates that the gas-sensitive material has broad spectrum property and sensitivity to various gases; if selective SL_x< 20%, indicating that the gas-sensitive material is almost non-responsive to gas x.

The selectivity of different gas-sensitive materials can be measured experimentally, for example, by measuring WO₃Resistance change of the nanowires to obtain WO₃The sensitivity of the nano-wire can obtain the selectivity of the gas sensitive material to different gases.

WO₃The results of the experiments on the selectivity of various hazardous gases are as follows:

H2S

EtOH

NH3

CH4

CO

H2

Butane

sensitivity S

62

20

1.6

0.8

1.2

13

1.4

Selective SL

62.00％

20.00％

1.60％

0.80％

1.20％

13.00％

1.40％

From the above experimental results, it can be judged that WO is contained in the present mixed gas₃Nanowire pair H₂S is a specific response, broad spectrum response to EtOH, and little response to other gases.

Because the gas sensitive material has different response sensitivity selectivity to different gases, if the concentration of the target gas is to be accurately detected, the gas sensitive material needs to be screenedAnd selecting a plurality of gas-sensitive materials with obvious differences in selectivity to form multi-parameter detection. SnO2, WO3 and In are preferably selected through comparison experiments₂O₃And NiO and other nano materials are used as gas detection parameters.

Each heating zone of the micro-heating structure provides a heating temperature matched with the response temperature of different gas-sensitive materials. When a gas sensitive film on the surface of the measuring electrode is contacted with a certain gas, the resistivity is obviously changed at a specific temperature, and the type and the concentration of the gas are determined according to the resistivity change conditions of the measuring electrodes in different heating areas. Because the response temperatures of different sensing materials are different, the micro-heating structure provides heating zones with different temperatures for heating different sensing materials, so that the cross detection of multiple sensing materials on a single microchip at different temperatures is realized, and the complex atmosphere detection function is realized.

Relevant parameters of the micro-heating structure can be determined by analysis of the thermal process of the heating electrode. The transient heat transfer process affects the thermal equilibrium rate and dynamic thermal stability of the gas sensor. Is characterized by the relationship between the power consumption P and the change of the specific heat capacity C, the temperature T, the thermal resistance R and the time T:

for a material with density ρ and volume V, the specific heat capacity is C ═ C_Vρ V. When the time constant is τ ═ RC,

thus the real-time temperature change isWherein Tm is the steady state temperature T at which the heat quantity for heating and the heat quantity for dissipating are the same_m＝T_amb+P·R。

When the heating electrode reaches a preset temperature and starts to conduct heat in a stable state, each part of the micro-heating structure conducts heat transfer with the external environment, mainly thermal radiation, heat conduction from the central area to the periphery, heat conduction of contact gas and gas sensitive materials and environmental heat convection, and the expression formula is

Wherein G is_m·λ_m(T_MHP-T_amb) Denotes center to cantilever heat conduction, G_air(h_f+λ_air)·(T_MHP-T_amb) Which means the heat conduction between the heterogeneous materials,represents thermal convection; wherein λ is_mDenotes the heat transfer coefficient, λ, of the micro-hotplate_airDenotes the heat transfer coefficient of air, h_fThe heat conduction in the direction of the suspension beam can be regarded as one-dimensional heat conduction, the cross section area of the suspension beam is Abeam, the length is l, in addition to the heat loss of the heat conduction, the larger the surface area of the heating layer is, the more the heat loss is contacted with the external environment is, and the larger the generated temperature gradient is. The resistance value of the heating electrode is expressed asIt follows that the thermal resistance is proportional to the length of the conductive path, l, inversely proportional to the cross-sectional area traversed and inversely proportional to the thermal conductivity, given the material.

The thermal analysis shows that the steady-state temperature of the micro-heating structure can be changed in three aspects, wherein the first is to change the thermal resistance of the heating electrode; the second way adjusts the heating power, namely the magnitude of the voltage value applied to the two ends of the heating electrode; thirdly, the distance between the heating electrodes is adjusted, and the heating temperature is higher when the distance is denser. The improvement of thermal uniformity requires a reduction of the thermal resistance, which can be achieved by, on the one hand, selecting materials with high thermal conductivity coefficients and, on the other hand, optimizing the geometry factor of the heating electrode. Specifically, thermal uniformity is improved by reducing the effective length l of the heated region or increasing the cross-sectional area, which also results in increased heat conduction during steady state thermal processes. In addition, the thermal resistance is reduced, so that the response rate of heat conduction is improved, and the time for the sensing structure to quickly reach thermal equilibrium is shortened.

And (3) integrating the analysis, designing heating layers in different temperature areas, and heating the sensing structure in a subarea manner on the same micro-heating structure so as to realize the complex atmosphere detection function of the sensor.

Example one

Fig. 2 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor according to an embodiment of the present invention. The heating layer of this embodiment includes heating electrode, heating electrode is many different heating resistor wires of cross-sectional area, and is many heating resistor wire forms a plurality of the zone of heating. As shown in fig. 2, the heating electrodes include a first heating resistance wire 211, a second heating resistance wire 212, and a third heating resistance wire 213. The sectional area of the first heating resistance wire 211 is larger than that of the second heating resistance wire 212, and the sectional area of the second heating resistance wire 212 is larger than that of the third heating resistance wire 213. The first heating resistance wire 211, the second heating resistance wire 212 and the third heating resistance wire 213 are respectively connected end to form a ring shape, and the three heating resistance wires are distributed on the silicon-based substrate in a gradient manner. The ring formed by the second heating resistance wire 212 is positioned in the ring formed by the third heating resistance wire 213, and the ring formed by the first heating resistance wire 211 is positioned in the ring formed by the second heating resistance wire 212. The heating layer further comprises a heating electrode pad 23 and a heating electrode lead 25, wherein the heating electrode lead 25 penetrates through a circular ring formed by the first heating resistance wire 211, the second heating resistance wire 212 and the third heating resistance wire 213 and is connected with the heating electrode pad 23. The first heating resistance wire 211 forms the first heating zone 201, the second heating resistance wire 212 forms the second heating zone 202, and the third heating resistance wire 213 forms the third heating zone 203. Measuring electrodes (not shown in figure 2) are arranged in each heating zone and coated with gas sensitive films to form a sensing structure.

According to joule's law, the heat generated by the current passing through a conductor is proportional to the square of the current, to the resistance of the conductor, and to the time of energization. That is, a certain voltage is applied to the two ends of the heating resistance wire, and the heat generated by the circuit is presented on the heating resistance wire in the form of temperature. In the same circuit, under the condition that the density of the flowing current is constant and the electrifying time is constant, the resistance of the heating resistance wire can be changed to present different temperatures. The resistance calculation formula R ═ ρ · L/S ═ ρ · L/(w · t), where ρ denotes the resistivity of the heating resistance wire (related to the gas sensitive sensing material), L denotes the length of the heating resistance wire, S denotes the cross-sectional area of the heating resistance wire (S ═ w · t), w denotes the cross-sectional width of the heating resistance wire, and t denotes the cross-sectional thickness of the heating resistance wire. According to the resistance calculation formula, the resistance of the heating resistance wire can be increased by prolonging the length of the heating resistance wire or reducing the cross section, so that the heating resistance wire presents higher temperature, and vice versa. Therefore, the length and the sectional area of the heating resistance wire can effectively influence the temperature distribution. Generally, the heating temperature required by the gas-sensitive sensing material is between 100 and 700 ℃, the resistance R of the heating electrode is between 70 and 250 omega, and the thickness of the deposited heating resistance wire (i.e. the section thickness t) is between 300 and 500 nm. The cross-sectional width w of the heating resistance wire is 10-100 μm and the length L is 1.5-20 mm according to the resistance formula.

The heating resistance wires are arranged at intervals, and the distance d between two adjacent heating resistance wires is 2-5 times of the section width w of the heating resistance wires (if the section widths of the two adjacent heating resistance wires are not equal, the distance between the two adjacent heating resistance wires is 2-5 times of the section width of the heating resistance wire with the larger section width). According to the simulation result, when the section width w is more than 50 μm, and the relation between the distance d between two adjacent heating resistance wires and the section width w is that d is more than or equal to 2w and less than or equal to 5w, the temperature gradient of at least 6 ℃ is formed between the two adjacent heating resistance wires from the center of the heating layer to the edge direction of the heating layer, and the temperature is reduced along with the increase of the radial length to form heating zones with different temperatures; the temperature difference of each heating area can be increased by increasing the distance between two adjacent heating resistance wires.

In this embodiment, the temperature of the third heating region 203 is lower than that of the second heating region 202, the temperature of the second heating region 202 is lower than that of the first heating region 201, and three heating regions with temperature gradients are formed on the heating layers. The gas sensing material with higher heating temperature requirement is coated on the first heating zone 201, the gas sensing material with lower heating temperature requirement is coated on the third heating zone 203, and the gas sensing materials of the first heating zone 201, the second heating zone 202 and the third heating zone 203 respectively detect specific gas components. Under the condition that 8V voltage is loaded at two ends of a heating electrode lead, the highest heating temperature of the first heating area 201 can reach about 600 ℃, the heating temperature of the second heating area 202 is about 500 ℃, the lowest heating temperature of the third heating area 203 is 350 ℃, heating areas with different temperature gradients are realized through the same heating resistance wire, and multiple gas-sensitive sensing materials are simultaneously heated on the same heating layer.

Example two

Fig. 3 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor according to a second embodiment of the present invention. The heating layer of the embodiment comprises a heating electrode 21, wherein the heating electrode 21 is a heating resistance wire with a plurality of sections with different sectional areas, and the plurality of sections of the heating resistance wire form a plurality of heating areas. As shown in fig. 3, the heating resistance wires include a first segmented resistance wire 21a, a second segmented resistance wire 21b, and a third segmented resistance wire 21c, the first segmented resistance wire 21a forms a first heating area 201, the second segmented resistance wire 21b forms a second heating area 202, and the third segmented resistance wire 21c forms a third heating area 203. The heating resistance wires are arranged in a serpentine curve, and the measuring electrodes 22 are distributed in the curved arc area of the heating resistance wires. The heating layer further comprises a pair of heating electrode pads 23 and a plurality of pairs of measuring electrode pads 24, two ends of the heating resistance wire are connected with the heating electrode pads 23, and the measuring electrodes 22 are respectively connected with the corresponding measuring electrode pads 24.

The resistance calculation formula R ═ ρ · L/S ═ ρ · L/(w · t), where ρ denotes the resistivity of the heating resistance wire (related to the gas sensitive sensing material), L denotes the length of the heating resistance wire, S denotes the cross-sectional area of the heating resistance wire (S ═ w · t), w denotes the cross-sectional width of the heating resistance wire, and t denotes the cross-sectional thickness of the heating resistance wire. Generally, the heating temperature required by the gas-sensitive sensing material is between 100 and 700 ℃, the resistance R of the heating electrode is between 70 and 250 omega, and the thickness of the deposited heating resistance wire (i.e. the section thickness t) is between 300 and 500 nm. The width w of the section of the heating resistance wire is 50-150 μm and the length L is 10-20 mm according to the resistance calculation formula.

The cross-sectional widths of the first sectional resistance wire 21a, the second sectional resistance wire 21b and the third sectional resistance wire 21c are sequentially increased, and the heating temperatures of the first heating area 201, the second heating area 202 and the third heating area 203 are sequentially reduced. Referring to fig. 4, under the condition that 8V voltage is loaded at two ends of the heating resistance wire, the highest heating temperature of the first heating zone 201 can reach about 600 ℃, the lowest heating temperature of the third heating zone 203 can reach 350 ℃, heating zones with different temperature gradients are realized through the same heating resistance wire, and multiple gas-sensitive sensing materials are simultaneously heated on the same heating zone.

The temperature difference of each heating area of the micro-heating structure in the first embodiment and the second embodiment can reach 200 ℃ at most, and the gas-sensitive sensing material with large response temperature difference is particularly suitable for the micro-heating structure in the first embodiment and the second embodiment. For example, SnO₂、WO₃、In₂O₃And the optimal response temperatures of the four gas-sensitive sensing materials NiO are respectively as follows: SnO₂(600℃)、WO₃(350℃)、In₂O₃(250 ℃) and NiO (400 ℃), the gas sensor manufactured by respectively coating the measuring electrodes with the four materials can correspondingly detect 4 gases or mixed gases containing the 4 gases.

EXAMPLE III

Fig. 5 is a schematic diagram of a heating layer of a multi-dimensional multi-parameter gas sensor provided in the third embodiment of the present invention. The heating layer of the embodiment includes a heating electrode 21, the heating electrode 21 is distributed in the center of the heating layer 20, and the measuring electrode 22 is distributed around the heating electrode 21. The number of the measuring electrodes 22 is 4, the heating electrodes 21 and the measuring electrodes 22 are arranged on the same plane of the silicon-based substrate 10, the 4 pairs of measuring electrodes 22 are all adjacent to the heating electrodes 21, and the 4 pairs of measuring electrodes 22 are heated in a co-sheet mode through the heating electrodes 21. The surface of the silicon substrate 10 is provided with a pair of heating electrode pads 23 and 4 pairs of measuring electrode pads 24, two ends of the heating electrode 21 are led out to the heating electrode pads 23, and the measuring electrodes 22 are respectively led out to the corresponding measuring electrode pads 24.

As shown in fig. 6, m denotes a geometric length of the heating layer, h denotes a geometric length of a region where the heating electrode is distributed, and C denotes a geometric length of the cavity of the silicon-based substrate. As shown in fig. 7, it can be found from the relationship between the power and the ratio m/h of the geometric length of the heating layer to the geometric length of the region where the heating electrodes are distributed, and the geometric length m of the heating layer is 1 to 6 times the geometric length h of the region where the heating electrodes are distributed. The geometric length m of the heating layer is 500-3000 μm, and the geometric length h of the distribution region of the heating electrode 21 is 85-3000 μm. The relationship between m/h and power consumption is shown in FIG. 7. The layout of the heating electrodes and the measuring electrodes is related to the thermal uniformity, as shown in fig. 8, as m/h increases, the temperature gradient per micron from the temperature center (heating electrode) to the edge of the heating layer changes less, although the power and uniformity are better with a larger ratio, it is not advisable to increase the range of m/h any more from the viewpoint of processing and economic efficiency.

The cavity 13 of the silicon-based substrate 10 is beneficial to the heating layer 20 with the heating electrode 21 arranged at the center to reach higher working temperature, the geometric length C of the cavity 13 is not more than twice of the geometric length h of the area where the heating electrode 21 is distributed, namely C/h is more than or equal to 0 and less than or equal to 2, and when the ratio of C/h is maximum, the temperature of the heating layer 20 can reach stable 700 ℃. The geometric length h of the distribution area of the heating electrode 21 is 85-3000 μm, and the geometric length C of the cavity 13 is preferably 50-6000 μm. The measuring electrode 22 can adopt an interdigital structure, and the line width and the space of the interdigital structure are both 1-10 mu m. The heating electrode 21 is formed by winding a heating resistance wire, the thickness t of the heating resistance wire is 300nm-500nm, and the width w of the heating resistance wire is 10 mu m-100 mu m. The distance d between the two surrounding sections of the heating resistance wire is less than twice the width w of the heating resistance wire, namely d is less than 2 w. The required heating temperature of the gas-sensitive sensing material can reach 700 ℃ at most, the resistance R of the micro-heating structure is usually between 90 and 200 Ω, and a resistance calculation formula R is rho-L/S is rho-L/(w-t), wherein rho represents the resistivity of the heating resistance wire (related to the gas-sensitive sensing material), L represents the length of the heating resistance wire, S represents the sectional area of the heating resistance wire (S is w-t), w represents the width of the heating resistance wire, t represents the thickness of the heating resistance wire, and the length range of the heating resistance wire L is calculated according to the resistance formula to be 1.5-13 mm.

Fig. 9 is a simulation diagram of the temperature distribution of the heating layer of the present embodiment, under the simulation conditions: the geometric length m of the heating layer is 500 mu m, the geometric length h of the region where the heating electrodes are distributed is 245 mu m, the m/h of the heating electrode is 500 mu m/245 mu m of the heating electrode is 2, the line width w of the heating resistance wire is 20 mu m, the distance d of the heating resistance wire is 50 mu m, and the thickness t of the heating resistance wire is 300 nm. Referring to fig. 9, under the above simulation conditions, the heating temperature was about 610 ℃ at a heating power of 48mW, and the temperature difference between the heating layers was small.

The micro-heating structure of the embodiment has small temperature difference of each heating area, and is suitable for gas-sensitive sensing materials with small response temperature difference (within 30 ℃). For example, the optimum working temperature for detecting hydrogen sulfide gas by using WO3 nano wires is 350 ℃, and the optimum working temperature for detecting CO by using flower-shaped SnO2 is also 350 ℃.

Example four

Fig. 10 is a block diagram of a signal detection system of a multi-dimensional multi-parameter gas sensor according to a fourth embodiment of the present invention. As shown in fig. 10, the signal detection system of the present embodiment includes a signal detection module, a signal processing module, an alarm module, and a wireless communication module. The signal detection module is used for acquiring a plurality of paths of electric signals generated by the measuring electrode and measuring the resistance values corresponding to the electric signals. Fig. 11 is a block diagram of a signal detection module of the signal detection system according to the fourth embodiment of the present invention, and as shown in fig. 11, the signal detection module includes an analog switch circuit, a driving circuit, and an analog-to-digital conversion circuit, which are connected in sequence. The analog switch circuit is connected with the measuring electrode and used for acquiring a plurality of paths of electric signals generated by the measuring electrode, and the plurality of paths of electric signals are analog electric signals. The analog-to-digital conversion circuit is used for converting the analog electric signal into a digital signal and outputting the digital signal. As shown in fig. 12, the analog switch circuit in this embodiment is a four-bidirectional analog switch circuit, the four-bidirectional analog switch circuit is connected to the plurality of measurement electrodes, and a CD4066 four-bidirectional analog switch is adopted, each analog switch has three terminals of input, output, and control, and can simultaneously obtain 4 paths of analog electrical signals generated by 4 pairs of measurement electrodes, thereby realizing multiplexing transmission of the analog signals. As shown in fig. 13, the driving circuit in this embodiment is a four-way driving circuit, and a TLV3544 four-channel operational amplifier is adopted, so that low-level or high-level analog input can be processed without external signal conditioning hardware. As shown in fig. 14, the analog-to-digital conversion circuit in this embodiment adopts an AD7833 bridge circuit to accurately measure the resistance change of the sensing structure, and converts an analog electrical signal into a digital signal for output. The input ends of the four driving circuits are correspondingly connected with the output ends of the four bidirectional analog switch circuits, the output ends of the four driving circuits are connected with the analog-to-digital conversion circuit, and the circuit structure can simultaneously measure the change of a plurality of groups of resistors of the sensing structure to realize multi-channel signal detection.

The signal processing module is connected with the signal detection module and used for determining the category and the concentration of the gas corresponding to the electric signal according to the change situation of the resistance value corresponding to the electric signal. Fig. 15 is a schematic circuit diagram of a signal processing module of a signal detection system according to a fourth embodiment of the present invention, and as shown in fig. 15, the signal processing module includes a single chip microcomputer, and the single chip microcomputer is configured to determine a type and a concentration of a gas corresponding to an electrical signal according to a change condition of a resistance value corresponding to the electrical signal, and output a type signal and a concentration signal of the gas. In this embodiment, an STM32 single chip microcomputer is adopted, an algorithm for determining the type and concentration of the gas is written into a program code, the program code is burnt into the STM32 single chip microcomputer, and the STM32 single chip microcomputer determines the type and concentration of the gas corresponding to the digital signal according to the digital signal output by the analog-to-digital conversion circuit, so that a gas detection function is realized. The algorithm of the signal detection system comprises a temperature and humidity compensation algorithm, a signal drift calibration algorithm, a multi-channel signal identification algorithm, an alarm value and a transmission display mode setting. The signal detection system further comprises a heating circuit, wherein the heating circuit is connected with the single chip microcomputer and used for providing heating voltage for a heating electrode of the micro-heating structure.

The alarm module is connected with the singlechip and used for receiving the category signal and the concentration signal of the gas and generating an alarm signal when the concentration signal of the gas exceeds a preset threshold value of the gas concentration. And the preset threshold is uploaded to the singlechip through the burning port. The alarm module comprises a light emitting diode and a buzzer, when the single chip microcomputer judges that the concentration signal exceeds a preset threshold value, an alarm signal is generated, the light emitting diode is lightened, the buzzer sounds, and danger is warned.

The wireless communication module is connected with the single chip microcomputer and used for wirelessly transmitting the category signal and the concentration signal of the gas to external monitoring equipment, so that the gas concentration data can be remotely read in real time. The wireless communication module is, for example, a ZigBee communication module, a Bluetooth communication module or an RS-232/485 communication module.

The signal detection system also comprises a temperature and humidity monitoring module, wherein the temperature and humidity monitoring module is connected with the single chip microcomputer and is used for monitoring the ambient temperature and the ambient humidity in real time and outputting a temperature signal and a humidity signal; the single chip microcomputer is further used for determining the type and concentration of the gas corresponding to the electric signal according to the temperature signal, the humidity signal and the change situation of the resistance value corresponding to the electric signal. For example, the single chip microcomputer reasonably compensates the influence of the temperature and the humidity on the resistance value according to a pre-programmed program instruction (the change relation between the temperature and the humidity and the resistance value), and improves the accuracy of gas detection.

The signal detection system adopts loop power supply, the power supply requirement of the single chip microcomputer can be met through a lithium ion battery or a household No. 5 battery, and the sensing structure and the signal detection module are both powered by the single chip microcomputer. For example, the singlechip outputs 0-5V heating voltage to the gas sensing module to supply power to the heating electrode, and the heating electrode provides different heating temperatures for each measuring electrode. The voltage of the heating electrode can be adjusted according to the actual temperature requirement, the adjustable voltage precision is 0.2V, and the average distribution is in the range of 0-5V. The driving capability can reach more than 100mA by outputting current to the heating electrode through a TLV3544 four-channel operational amplifier.

The signal detection system provided by this embodiment measures the resistance values corresponding to the multiple electrical signals respectively through the signal detection module, and then determines the type and concentration of the gas corresponding to each electrical signal according to the change conditions of the resistance values corresponding to the electrical signals through the signal processing module, so that the cross detection of multiple gas-sensitive materials at different temperatures can be realized, and the concentrations of multiple harmful gases can be detected at the same time. The same signal detection module can simultaneously acquire and measure the multi-channel electric signals generated by the sensing structure, a plurality of signal detection modules are not required to be arranged, and the system volume is reduced. The whole sensing structure is suitable for the same set of driving circuit and transmission circuit, greatly reduces the space required by the circuit, and meets the requirements of integration and miniaturization of the gas sensing device.

The gas sensor provided by the embodiment of the invention realizes the concentration detection of multi-parameter gas based on three dimensions of selectivity, broad-spectrum response and temperature characteristics of gas sensitive materials. The method comprises the steps of screening a plurality of gas-sensitive sensing materials which respond to specific gas according to selectivity of the gas-sensitive materials to form a sensing structure, designing a corresponding micro-heating structure according to the broad-spectrum response of the gas-sensitive sensing materials, providing different heating temperatures for the sensing structure through the micro-heating structure, and determining the concentrations of a plurality of target gases through a signal detection system according to the signal change condition generated by the sensing structure. The invention realizes complex atmosphere detection by combining multiple gas-sensitive sensing materials on a single gas sensor based on the selectivity, broad-spectrum response and temperature characteristics of the gas-sensitive materials, reduces the volume of the whole device and improves the integration level.

EXAMPLE five

Fig. 16 is a flowchart of a method for manufacturing a multidimensional multiparameter gas sensor according to a fifth embodiment of the present invention. As shown in fig. 16, the method for manufacturing a multi-dimensional multi-parameter gas sensor provided in this embodiment includes the following steps:

s1) manufacturing a heating layer on the silicon-based substrate to form the micro-heating structure.

And manufacturing a plurality of heating resistance wires with different sectional areas or a heating resistance wire with a plurality of sections with different sectional areas on the silicon-based substrate to form a plurality of heating zones with different temperatures.

For example, a plurality of heating resistance wires with different cross-sectional areas are manufactured on the silicon-based substrate by adopting an etching process or a photoetching stripping process, and the plurality of heating resistance wires form a plurality of heating zones with different temperatures. For example, an SOI wafer layer having p-type boron-doped Silicon (Si) is used as a Silicon-based substrate, and an SOI (Silicon-On-Insulator), i.e., Silicon On an insulating substrate, Silicon wafer means that a buried oxide layer (BOX) is introduced between a top Silicon layer and a back substrate as a support layer, and a Silicon oxide or Silicon nitride thin film layer having a thickness of not more than 1 μm is coated On the front and back surfaces of the Silicon wafer by using a plasma enhanced chemical vapor deposition method. Rotationally coating a thin photoresist film on the surface of a silicon wafer, partially evaporating a photoresist solvent by heating, and accurately aligning by using a pre-customized mask plate; and exposing a specified area on the photoresist by adopting an ultraviolet lithography technology, and performing heating layer metal evaporation with the thickness of 100-500nm on the exposed surface of the photoresist in a vacuum evaporation mode. And putting the evaporated silicon wafer into an acetone solution to be soaked for 4-5 hours to dissolve the photoresist and wash away the redundant evaporated metal to form a heating layer.

S2) manufacturing a plurality of measuring electrodes on the micro heating structure, and coating a corresponding gas sensitive film on the surface of each measuring electrode to form a sensing structure.

And manufacturing measuring electrodes in the heating zones with different temperatures, and coating a gas sensitive film matched with the heating temperature of the heating zone where the measuring electrode is positioned on the surface of each measuring electrode. For the condition that the heating resistance wire and the measuring electrode are positioned on the same plane, the measuring electrode can be simultaneously manufactured in the process of manufacturing the heating resistance wire. For example, a sacrificial layer is manufactured on the surface of a silicon substrate, images of a heating resistance wire and a measuring electrode are formed on the surface of the silicon substrate through a photoetching process, and the heating resistance wire and the measuring electrode are etched to the sacrificial layer through an etching process.

The metal oxide nano material is prepared by adopting a hydrothermal method, a solvothermal method and a microwave synthesis method and is used as a gas-sensitive sensing material. The synthesis process adopts high temperature and high pressure conditions to promote the conversion of metal salt into metal oxide. The whole synthesis process simultaneously carries out in-situ reaction, is beneficial to the transfer of electrons between the two, thereby improving the gas-sensitive property of the material, and is suitable for metal oxides with different shapes (nano particles, nano wires, nano sheets and the like) and different states (dispersion liquid, solid powder and the like). The metal oxide nano material prepared by the method is a specific or broad-spectrum gas-sensitive material and can react with oxidizing and reducing gases. A method of coating a gas-sensitive material on the surface of a measurement electrode, for example: and the gas sensitive film is formed after the coated gas sensitive material is dried.

S3) manufacturing the micro heating structure and the sensing structure into a micro sensing chip.

And selecting a proper micro-heating structure according to the temperature difference delta T of the working temperature of the gas-sensitive sensing material. If the temperature difference delta T of the optimal working temperature range of the selected gas-sensitive sensing material is within 0-30 ℃, the micro-heating structure provided by the third embodiment can be adopted. If the temperature difference delta T of the optimal working temperature range of the selected gas-sensitive sensing material is larger than 30 ℃, the micro-heating structure provided by the first embodiment or the second embodiment can be adopted, and the temperature of different areas can be adjusted by changing the line width and the distance of the heating resistance wires.

For example, by reacting SnO₂、WO₃、In₂O₃The gas-sensitive performance test of the NiO nano material shows that the four sensing materials are in NO₂、H₂S, CO in the mixed gas, the selectivity is more than or equal to 20 percent_xThe range is less than 60%, and the device has the characteristic of broad-spectrum response. The optimal working temperatures of the four materials were measured as follows: SnO₂(600℃)、WO₃(350℃)、In₂O₃250 ℃ and NiO 400 ℃, and the temperature difference delta T of the optimal working temperature range is obtained by using the four materials as gas-sensitive sensing materials>And at 30 ℃, adopting the micro heating structure provided by the first embodiment or the second embodiment.

And integrating and packaging the selected micro heating structure and the sensing structure into a micro sensing chip.

S4) the circuit board integrated with the signal detection system and the micro sensing chip are packaged into a whole.

And integrating all modules and circuits of the signal detection system provided by the third embodiment on a circuit board, and packaging the micro-sensing chip and the circuit board into a whole. The gas-sensitive nano material is integrated on a micro sensing chip processed by an MEMS technology, and the micro sensing chip is required to be packaged in order to avoid deformation or influence on an electrode signal conversion function. The packaging structure adopts a ceramic shell, the surface of the packaging structure is provided with a porous structure, the target gas can be conveniently and fully diffused, and the ceramic shell has the advantages of corrosion resistance, ageing resistance and small structure.

The embodiment of the invention also provides a gas detection method, which is used for detecting gas by using the multi-dimensional multi-parameter gas sensor. The gas detection method comprises the steps of detecting mixed gas consisting of more than two gases, realizing gas concentration detection through selectivity, broad-spectrum response and temperature characteristics of gas sensitive materials, selectively distinguishing target gases from complex gas mixtures, and improving the accuracy of multi-component gas detection.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solutions of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and these simple modifications all fall into the protection scope of the embodiments of the present invention. It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations. In addition, any combination of various embodiments of the present invention is also possible, and the embodiments of the present invention should be considered as disclosed in the present invention as long as the combination does not depart from the spirit of the embodiments of the present invention.