Gas detection device based on barrier modulation

Abstract

The invention provides a gas detection device based on barrier modulation. The gas detection device comprises a substrate; the detection assembly is arranged on the substrate, and the detection assembly comprises a sensor which comprises a base arranged on the heating module; the two electrodes are arranged on the substrate at intervals; the sensitive layer is arranged on the substrate and located between the two electrodes, and a Schottky barrier is formed between the two electrodes and the sensitive layer; the heating module is suitable for heating the sensitive layer; when the power supply module works in a first operation mode, sensitive gas in the volatile organic compound is enriched on the sensitive layer in a physical adsorption mode, when the power supply module works in a second operation mode, the height of the Schottky barrier is reduced, and the heating module heats the sensitive layer to a target temperature. Enabling the sensitive gas to be subjected to oxidation-reduction reaction on the sensitive layer to generate electrons and generate a detection signal; and the signal processing assembly is arranged on the substrate and is suitable for receiving the detection signal and obtaining the concentration of the sensitive gas according to the detection signal.

Description

Technical Field

[0001] The present disclosure relates to the technical field of sensor equipment, and more particularly, to a gas detection device based on barrier modulation. Background Art

[0002] There are many types of indoor volatile organic compounds, which are extremely harmful to human health and have therefore attracted widespread attention. According to statistics, the concentration of volatile organic compounds released from building materials in residential buildings, leather seats in car and aircraft cabins, and human activities (cooking and smoking, etc.) is generally within 100 ppb. There is clear evidence that toluene at a concentration of 70 ppb will affect people's cognitive performance. The "Indoor Air Quality Standard" GB / T 18883 2022 also stipulates that the toluene concentration shall not exceed 53 ppb and the total volatile organic compounds shall not exceed 186 ppb.

[0003] Developing economical and accurate online detection technology is the key to achieving precise control of volatile organic compounds and reducing carbon emissions. Low-cost, small portable sensors such as metal oxide semiconductor materials are gradually being used. The unique physical and chemical properties of semiconductor materials make them very sensitive to volatile organic compound gases and have good scalability, allowing them to react at high temperatures or in harsh environments. Simple manufacturing processes also make them commercially viable. Gas sensing elements based on semiconductor materials are widely used in the detection of volatile organic compounds in the industrial field due to their high detection limits (parts per million, ppm). However, at present, metal oxide semiconductor sensing elements still cannot meet the detection of ultra-low concentrations of volatile organic compounds (parts per billion, ppb) indoors. Summary of the invention

[0004] To solve at least one of the technical problems in the prior art, an embodiment of the present disclosure provides a gas detection device based on barrier modulation, which can detect sensitive gases in low-concentration volatile organic compounds.

[0005] The embodiment of the present disclosure provides a gas detection device based on barrier modulation, comprising: a substrate; a detection component, arranged on the substrate, suitable for detecting volatile organic compounds and outputting a detection signal, the detection component comprising: a sensor, comprising: a substrate, arranged on the heating module; two electrodes, arranged on the substrate at intervals; a sensitive layer, arranged on the substrate and located between the two electrodes, a Schottky barrier is formed between the two electrodes and the sensitive layer; and a heating module, suitable for heating the sensitive layer through the substrate; a power supply module, configured to operate in a first operation mode and a second operation mode alternately for The detection component is powered, wherein when the power supply module operates in the first operation mode, the sensitive gas in the volatile organic compound is enriched on the sensitive layer by physical adsorption, and when the power supply module operates in the second operation mode, the height of the Schottky barrier is reduced, and the heating module heats the sensitive layer to a target temperature, so that the sensitive gas in the volatile organic compound undergoes an oxidation-reduction reaction on the sensitive layer to generate electrons and generate the detection signal; and a signal processing component is arranged on the substrate and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal.

[0006] According to some embodiments of the present disclosure, during the process in which the heating module heats the sensitive layer to the target temperature, the sensitive gas enriched in the sensitive layer is continuously consumed, so that the generated electrons are reduced and the sensor enters a dielectric relaxation process.

[0007] According to some embodiments of the present disclosure, the above-mentioned sensor is arranged in plurality, and the sensitive layer of each of the above-mentioned sensors matches different sensitive gases in the above-mentioned volatile organic compounds, and respectively generates different detection signals; wherein different above-mentioned sensitive gases have different activation energies, so that different above-mentioned sensitive layers respectively matched with different above-mentioned sensitive gases have different voltage drop trends in the above-mentioned dielectric relaxation process.

[0008] According to some embodiments of the present disclosure, the material of the sensitive layer is a metal oxide with a granular structure, gaps are formed between the granular structures, and the sensitive gas penetrates into the gaps and diffuses evenly when the power supply module is in the first operating mode.

[0009] According to some embodiments of the present disclosure, the power supply module includes: a power supply voltage unit, configured to maintain the sensitive gas enriched on the sensitive layer; a first diode, connected in series with the power supply voltage unit; a dynamic voltage unit, connected in parallel with the power supply voltage unit; and a second diode, connected in series with the dynamic voltage unit; wherein the first diode and the second diode are respectively configured to be turned on or off according to the working state of the dynamic voltage unit, so that the voltage received by the sensor is periodically switched.

[0010] According to some embodiments of the present disclosure, the first operating mode is that when the dynamic voltage unit is turned off, the first diode is turned on, the second diode is turned off, and the voltage received by the sensor is the supply voltage; the second operating mode is that when the dynamic voltage unit is turned on, the first diode is turned off, the second diode is turned on, and the voltage received by the sensor is the dynamic voltage.

[0011] According to some embodiments of the present disclosure, the detection component further includes: at least one amplification circuit, each of the amplification circuits being adapted to amplify the detection signal output by one of the sensors.

[0012] According to some embodiments of the present disclosure, each of the above-mentioned amplification circuits includes a load resistor and an operational amplifier, and the sensor response formula of the above-mentioned amplification circuit is: ;in, It is expressed as the response of the above sensor in a mixed gas containing the above sensitive gas, Expressed as the above supply voltage, Expressed as the above dynamic voltage, It is expressed as the output voltage of the above sensor in a mixed gas containing the above sensitive gas, It is expressed as the output voltage of the above sensor in clean air, Expressed as the load resistance mentioned above.

[0013] According to some embodiments of the present disclosure, the amplification factor of the above-mentioned amplifier circuit is: ; where q represents the elementary charge, represents the barrier height of the above Schottky barrier, K represents the Boltzmann constant, T represents the temperature, , It is expressed as the reduction in the Schottky barrier after applying the dynamic voltage.

[0014] According to some embodiments of the present disclosure, the above-mentioned signal processing component includes: an analog-to-digital conversion unit, arranged on the above-mentioned substrate, configured to convert each detection signal into a digital signal; a data transmission unit, arranged on the above-mentioned substrate, configured to transmit a plurality of the above-mentioned digital signals; and a calculation unit, communicatively connected to the above-mentioned data transmission unit, configured to receive and perform calculations based on the above-mentioned digital signals to obtain the concentration of the sensitive gas in the above-mentioned volatile organic compound.

[0015] According to a gas detection device based on barrier modulation in an embodiment of the present disclosure, a detection component is arranged on a substrate, the detection component is suitable for detecting volatile organic compounds and outputting a detection signal, the detection component includes a sensor, the sensor includes a substrate, two electrodes, a sensitive layer and a heating module, the substrate is arranged on the heating module, the two electrodes are arranged on the substrate at intervals, the sensitive layer is arranged on the substrate and is located between the two electrodes, a Schottky barrier is formed between the two electrodes and the sensitive layer, and the heating module is suitable for heating the sensitive layer through the substrate. The power supply module is configured to supply power to the detection component in a manner of alternating operation between a first operating mode and a second operating mode. When the power supply module operates in the first operating mode, the sensitive gas in the volatile organic compounds is enriched on the sensitive layer by physical adsorption, and when the power supply module operates in the second operating mode, the height of the Schottky barrier is reduced, and at the same time, the heating module heats the sensitive layer to a target temperature, so that the sensitive gas in the volatile organic compounds undergoes an oxidation-reduction reaction on the sensitive layer to generate electrons, and the electrons are more easily diffused from the sensitive layer to the two electrodes to generate a detection signal. The signal processing component is arranged on the substrate, and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal. The gas detection device based on barrier modulation can detect the sensitive gas in the volatile organic compound with low concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0017] Figure 1 is a block diagram of a gas detection device based on barrier modulation according to an exemplary embodiment of the present disclosure;

[0018] Figure 2 is a circuit diagram of a gas detection device based on barrier modulation according to an exemplary embodiment of the present disclosure;

[0019] Figure 3 is a state diagram of a sensing mechanism of a sensor according to an illustrative embodiment of the present disclosure;

[0020] Figure 4 is a state diagram of a modulation mechanism of a Schottky barrier according to an illustrative embodiment of the present disclosure;

[0021] Figure 5 is a state diagram of a Schottky barrier according to an illustrative embodiment of the present disclosure;

[0022] Figure 6 is a circuit diagram of a power supply module according to an exemplary embodiment of the present disclosure.

[0023] In the drawings, the meanings of the reference numerals are as follows:

[0024] 1. Substrate;

[0025] 2. Detection components;

[0026] 21. Sensor;

[0027] 211, sensitive layer;

[0028] 212. Electrode;

[0029] 213, base;

[0030] 214. Micro heater;

[0031] 215, heating end;

[0032] 216. Electronics;

[0033] 217. Schottky barrier;

[0034] 22. Power supply module;

[0035] 221, supply voltage unit;

[0036] 222, dynamic voltage unit;

[0037] 223, a first diode;

[0038] 224, a second diode;

[0039] 3. Signal processing components;

[0040] 31. Analog-to-digital conversion unit;

[0041] 32. Data transmission unit;

[0042] 4. Amplifier circuit;

[0043] 41. Load resistance;

[0044] 42. Operational amplifier. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0046] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0047] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0048] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0049] In order to detect ultra-low concentration (parts per billion, ppb) of volatile organic compounds indoors, according to the inventive concept of one aspect of the present disclosure, a detection component is arranged on a substrate, the detection component is suitable for detecting volatile organic compounds and outputting a detection signal, the detection component includes a sensor, the sensor includes a substrate, two electrodes, a sensitive layer and a heating module, the substrate is arranged on the heating module, the two electrodes are arranged on the substrate at intervals, the sensitive layer is arranged on the substrate and located between the two electrodes, a Schottky barrier is formed between the two electrodes and the sensitive layer, and the heating module is suitable for heating the sensitive layer through the substrate. The power supply module is configured to supply power to the detection component in a manner of alternating operation in a first operating mode and a second operating mode. When the power supply module operates in the first operating mode, the sensitive gas in the volatile organic compounds is enriched on the sensitive layer by physical adsorption, and when the power supply module operates in the second operating mode, the height of the Schottky barrier is reduced, and at the same time, the heating module heats the sensitive layer to a target temperature, so that the sensitive gas in the volatile organic compounds undergoes an oxidation-reduction reaction on the sensitive layer to generate electrons, and the electrons are more easily diffused from the sensitive layer to the two electrodes to generate a detection signal. The signal processing component is arranged on the substrate, and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal. The gas detection device based on barrier modulation can detect the sensitive gas in the volatile organic compound with low concentration.

[0050] Figure 1 is a block diagram of a gas detection device based on barrier modulation according to an exemplary embodiment of the present disclosure, Figure 2 is a circuit diagram of a gas detection device based on barrier modulation according to an exemplary embodiment of the present disclosure.

[0051] According to the embodiments of the present disclosure, Figure 1 and Figure 2As shown, a gas detection device based on barrier modulation is provided, including a substrate 1, a detection component 2, a power supply module 22 and a signal processing component 3. The detection component 2 is arranged on the substrate 1, and is suitable for detecting volatile organic compounds and outputting a detection signal. The detection component 2 includes a sensor 21, and the sensor 21 includes a substrate 213, two electrodes 212, a sensitive layer 211 and a heating module. The substrate 213 is arranged on the heating module. The two electrodes 212 are arranged on the substrate 213 at intervals. The sensitive layer 211 is arranged on the substrate 213 and is located between the two electrodes 212, and a Schottky barrier 217 is formed between the two electrodes 212 and the sensitive layer 211. The heating module is suitable for heating the sensitive layer 211 through the substrate 213. The power supply module 22 is configured to power the detection component 2 in a manner of alternating between a first operating mode and a second operating mode. When the power supply module 22 operates in the first operation mode, the sensitive gas in the volatile organic compound is enriched on the sensitive layer 211 by physical adsorption. When the power supply module 22 operates in the second operation mode, the height of the Schottky barrier 217 is reduced, and the heating module heats the sensitive layer 211 to the target temperature, so that the sensitive gas in the volatile organic compound undergoes an oxidation-reduction reaction on the sensitive layer 211 to generate electrons 216, and the electrons 216 are more easily diffused from the sensitive layer 211 to the two electrodes 212 to generate a detection signal. The signal processing component 3 is arranged on the substrate 1, and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal.

[0052] According to an embodiment of the present disclosure, the heating module includes a micro heater 214 and a heating end 215, wherein the micro heater 214 is disposed on the lower side of the substrate 213, and the heating end 215 is disposed at the bottom of the micro heater 214, and the micro heater 214 heats the sensitive layer 211 through the substrate 213. Since the sensitive gas needs to reach the target temperature for the redox reaction to occur in the sensitive layer 211, when the power supply module 22 operates in the first operating mode, the sensitive layer 211 cannot reach the target temperature, therefore, the sensitive gas in the volatile organic matter is enriched in the sensitive layer 211 in large quantities by physical adsorption, so that the power supply module 22 can generate more electrons 216 when operating in the second operating mode, thereby improving the detection accuracy of the sensor 21.

[0053] According to an embodiment of the present disclosure, the material used to make the sensitive layer 211 may be a semiconductor material, such as tin oxide or zinc oxide.

[0054] In an illustrative embodiment, based on the sensitive layer 211 made of SnO2 sensitive material, the target temperature range at which the sensitive gas can undergo redox reaction on the sensitive layer 211 is 100°C~200°C, and when the power supply module 22 operates in the first operating mode, the operating temperature of the sensitive layer 211 is below 100°C, for example, it can be 30°C, 60°C or 90°C.

[0055] Figure 3 is a state diagram of a sensing mechanism of sensor 21 according to an exemplary embodiment of the present disclosure.

[0056] According to an embodiment of the present disclosure, the response of the sensor 21 can be identified by the resistance change caused by the mixed gas containing the sensitive gas. Figure 3 As shown, when the sensor 21 is exposed to the air, oxygen molecules are adsorbed on its sensitive layer 211 and occupy oxygen vacancies, and electrons 216 on the sensitive layer 211 are consumed to form oxygen ions, which will increase the resistance. Then, the reducing gas and oxygen ions on the sensitive layer 211 will undergo a redox reaction to generate electrons 216, resulting in a decrease in resistance and a decrease in the height of the Schottky barrier 217, so that the electrons 216 can more easily diffuse from the sensitive layer 211 to the two electrodes 212 to generate a detection signal.

[0057] According to the embodiment of the present disclosure, a Schottky barrier 217 or an Ohmic contact can be formed between the two electrodes 212 (metal material) and the sensitive layer 211 (semiconductor material). The Schottky barrier 217 is a built-in electric field. Since the Fermi level of the semiconductor material is higher than that of the metal material, when the two are in contact, the electrons 216 in the sensitive layer 211 diffuse toward the two electrodes 212. The lack of electrons 216 causes the side of the sensitive layer 211 in contact with the two electrodes 212 to be positively charged, and the other side of the two electrodes 212 in contact with the sensitive layer 211 to be negatively charged, thereby forming a built-in electric field in the direction from the sensitive layer 211 to the two electrodes 212. When the electrons 216 between the sensitive layer 211 and the two electrodes 212 reach equilibrium, the electrons 216 in the sensitive layer 211 must overcome the built-in electric field to diffuse to the two electrodes 212. Therefore, the direction of the dynamic voltage applied by the dynamic voltage unit 222 (the dynamic voltage unit 222 is described in detail below) in the power supply module 22 is opposite to the direction of the built-in electric field, thereby reducing the electric field strength and further reducing the Schottky barrier 217, making it easier for electrons 216 to diffuse to the two electrodes 212 and generate a detection signal.

[0058] According to an embodiment of the present disclosure, when the dynamic voltage is kept constant, the sensor 21 has the same transient response to a mixed gas containing a sensitive gas at a fixed concentration. The response S of the sensor 21 is defined as the resistance R in clean air. a Resistance R in a gas mixture containing sensitive gas g The ratio can be expressed by the following formula (1):

[0059] S= R a / R g (1).

[0060] According to the embodiment of the present disclosure, when the dynamic voltage changes periodically, the resistance of the sensor 21 will also change periodically. At this time, two responses are defined: S i With S e , S i It can be expressed by the following formula (2):

[0061] S i = R a / R g，5 (2);

[0062] Among them, S i Expressed as the resistance R in clean air a The resistance R determined 5s after applying a dynamic voltage in a gas mixture containing sensitive gas g，5 ratio.

[0063] According to an embodiment of the present disclosure, S e It can be expressed by the following formula (3):

[0064] S e = R a / R g，e (3);

[0065] Among them, S e Expressed as the resistance R in clean air a The resistance R determined after heating in a gas mixture containing sensitive gas g，e ratio.

[0066] According to an embodiment of the present disclosure, the detection component 2 is disposed on the substrate 1, and the detection component 2 is suitable for detecting volatile organic compounds and outputting a detection signal. The detection component 2 includes a sensor 21, and the sensor 21 includes a substrate 213, two electrodes 212, a sensitive layer 211, and a heating module. The substrate 213 is disposed on the heating module, and the two electrodes 212 are disposed on the substrate 213 at intervals. The sensitive layer 211 is disposed on the substrate 213 and is located between the two electrodes 212. A Schottky barrier 217 is formed between the two electrodes 212 and the sensitive layer 211, and the heating module is suitable for heating the sensitive layer 211 through the substrate 213. The power supply module 22 is configured to supply power to the detection component 2 in a manner of alternating between a first operating mode and a second operating mode. When the power supply module 22 operates in the first operation mode, the sensitive gas in the volatile organic compound is enriched on the sensitive layer 211 by physical adsorption. When the power supply module 22 operates in the second operation mode, the height of the Schottky barrier 217 is reduced, and the heating module heats the sensitive layer 211 to the target temperature, so that the sensitive gas in the volatile organic compound undergoes an oxidation-reduction reaction on the sensitive layer 211 to generate electrons 216, and the electrons 216 are more easily diffused from the sensitive layer 211 to the two electrodes 212 to generate a detection signal. The signal processing component 3 is arranged on the substrate 1, and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal. The gas detection device based on barrier modulation can detect the sensitive gas in the volatile organic compound with low concentration.

[0067] According to an embodiment of the present disclosure, when the heating module heats the sensitive layer 211 to the target temperature, the sensitive gas enriched in the sensitive layer 211 is continuously consumed, so that the generated electrons 216 decrease, and the sensor 21 enters a dielectric relaxation process.

[0068] Figure 4 is a state diagram of a modulation mechanism of the Schottky barrier 217 according to an exemplary embodiment of the present disclosure, Figure 5 is a state diagram of the Schottky barrier 217 according to an exemplary embodiment of the present disclosure.

[0069] According to the embodiments of the present disclosure, Figure 4 As shown, the power supply module 22 operates alternately in the first operation mode and the second operation mode to supply power to the detection component 2, and the response of the sensor 21 can be summarized into three processes: static process, transient process and non-static process. When the power supply module 22 operates in the first operation mode, the sensor 21 is in a static process, and the charge transfer at the interface between the two electrodes 212 and the sensitive layer 211 is in a balanced state, which cannot be destroyed by the physical adsorption process under low temperature conditions. Figure 4 and Figure 5As shown, when the power supply module 22 operates in the second operating mode (applying a forward bias voltage), the reduction of the barrier height of the Schottky barrier 217 (Δφ=Vs-Va, Vs represents the barrier height, and Va represents the supply voltage) causes a large number of electrons 216 to transition to the two electrodes 212, generating a detection signal. Under a fixed bias voltage, the output voltage and the barrier height respond exponentially. In the dynamic voltage modulation mode, the response of the sensor 21 mainly depends on the transient process, in which the transition of the electron 216 determines the effective signal transmission. In addition, the transient process is a coupling of several complex dynamic processes, such as charge transfer and diffusion, and contains the dynamic characteristics of the reacting electrons and the unreacted electrons. When the interface between the two electrodes 212 and the sensitive layer 211 enters a non-static process, due to the increase in temperature, the sensitive gas pre-enriched on the sensitive layer 211 in the static process will be continuously consumed, and the number of electrons 216 generated by the redox reaction will decrease accordingly, the output voltage will show a downward trend, and the sensor 21 will begin to undergo a dielectric relaxation process.

[0070] According to the embodiments of the present disclosure, dielectric relaxation means that under the action of an external electric field, the charges inside the material of the sensitive layer 211 are rearranged in response to the electric field. The dielectric relaxation process is not completed instantaneously but depends on the frequency of the electric field change.

[0071] According to an embodiment of the present disclosure, a plurality of sensors 21 are provided, and the sensitive layer 211 of each sensor 21 matches different sensitive gases in volatile organic compounds, and generates different detection signals respectively. Different sensitive gases have different activation energies, so that different sensitive layers 211 respectively matching different sensitive gases have different voltage drop trends in the dielectric relaxation process.

[0072] According to an embodiment of the present disclosure, a plurality of sensors 21 may share a heating module, or each of the plurality of sensors 21 may be configured with a heating module.

[0073] According to the embodiment of the present disclosure, different materials of the sensitive layer 211 match different sensitive gases in volatile organic compounds. When tin oxide is selected as the material of the sensitive layer 211, the sensitive gases that can be detected are, for example, formaldehyde, ethanol, and sulfur dioxide. When zinc oxide is selected as the material of the sensitive layer 211, the sensitive gases that can be detected are, for example, carbon dioxide, hydroxide, bromophenol, hydrogen sulfide, nitrogen oxides, and formaldehyde.

[0074] According to an embodiment of the present disclosure, the Schottky barrier 217 generated by the contact between tin oxide or zinc oxide and two electrodes 212 (metal material) is adjusted to detect the concentration of sensitive gas. The intensity of electrons 216 crossing the Schottky barrier 217 can be quantified by detecting the output voltage. The resistance change of the sensor 21 can be described according to the barrier height of the Schottky barrier 217. The barrier height of the Schottky barrier 217 determines the response and selectivity of the sensor 21.

[0075] According to the embodiments of the present disclosure, since different gases have different activation energies, the amounts enriched in the sensitive layer 211 are different, so that different sensitive layers 211 matched with different sensitive gases have different voltage drop trends during the dielectric relaxation process, and the resistance value of the sensor 21 increases differently. When the intensity of the redox reaction of the sensitive gas is large, the resistance value increases more; when the intensity of the redox reaction of the sensitive gas is small, the resistance value increases less. Therefore, the selectivity of the sensor 21 can be significantly improved by utilizing this phenomenon.

[0076] According to an embodiment of the present disclosure, the material of the sensitive layer 211 is a metal oxide with a granular structure, gaps are formed between the granular structures, and the sensitive gas penetrates into the gaps and diffuses evenly when the power supply module 22 is in the first operating mode.

[0077] In an illustrative embodiment, the sensitive layer 211 is a nano-scale tin oxide particle structure, and gaps are formed between the tin oxide particles. When the power supply module 22 is in the first operation mode, the toluene gas molecules diffuse and condense in the gaps of the sensitive layer 211. When the power supply module 22 is in the second operation mode, the Schottky barrier 217 is partially offset by the dynamic voltage, and the electrons 216 generated by the redox reaction of the toluene gas molecules are more likely to overcome the weakened Schottky barrier 217 to reach the two electrodes 212, generating a detection signal.

[0078] Figure 6 is a circuit diagram of a power supply module 22 according to an exemplary embodiment of the present disclosure.

[0079] According to the embodiments of the present disclosure, Figure 6 As shown, the power supply module 22 includes a power supply voltage unit 221, a first diode 223, a dynamic voltage unit 222, and a second diode 224. The power supply voltage unit 221 is configured to maintain the sensitive gas enriched on the sensitive layer 211. The first diode 223 is connected in series with the power supply voltage unit 221. The dynamic voltage unit 222 is connected in parallel with the power supply voltage unit 221. The second diode 224 is connected in series with the dynamic voltage unit 222. The first diode 223 and the second diode 224 are respectively configured to be turned on or off according to the working state of the dynamic voltage unit 222, so that the voltage received by the sensor 21 is periodically switched.

[0080] According to the embodiment of the present disclosure, the dynamic voltage unit 222 adopts a periodic start-stop operation mode, and the dynamic voltage start-stop cycle can be selected according to the mixed gas containing sensitive gas to be detected, and the dynamic voltage unit 222 is turned on for a time range of 30s to 150s, and the interval time range is 30s to 300s. For example, the dynamic voltage unit 222 is turned on for 30s and the interval time is 150s.

[0081] According to an embodiment of the present disclosure, the dynamic voltage unit 222 has an automatic start-stop function. After the dynamic voltage unit 222 is powered on, it will not be turned on immediately, but will start a delayed countdown. After the countdown ends, the power input sensor 21 will be turned on.

[0082] In an exemplary embodiment, the power supply voltage unit 221 is turned on and preheated for approximately 120 minutes, the dynamic voltage unit 222 is turned off for an interval of 300 seconds and turned on for 120 seconds, and the signal extracted during the process of the dynamic voltage unit 222 starting and stopping cyclically when the dynamic voltage unit 222 is turned on is the effective signal of the sensor 21 (S i and S e ), using S i and S e Determine the concentration of a gas mixture containing a sensitive gas.

[0083] According to an embodiment of the present disclosure, in the first operation mode, when the dynamic voltage unit 222 is turned off, the first diode 223 is turned on, the second diode 224 is turned off, and the voltage received by the sensor 21 is the supply voltage. In the second operation mode, when the dynamic voltage unit 222 is turned on, the first diode 223 is turned off, the second diode 224 is turned on, and the voltage received by the sensor 21 is the dynamic voltage.

[0084] According to an embodiment of the present disclosure, the supply voltage is 3V, and the dynamic voltage is greater than 3V but does not exceed 10V to prevent overload.

[0085] According to the embodiment of the present disclosure, the power supply voltage unit 221 is continuously turned on, and the output voltage is 3V, so as to maintain the sensitive gas enriched on the sensitive layer 211. When the dynamic voltage unit 222 is turned off, the first diode 223 is turned on, and due to the unidirectional conductivity of the second diode 224, the second diode 224 is turned off, preventing the power supply voltage from flowing to the dynamic voltage unit 222. At this time, the voltage received by the sensor 21 is the power supply voltage. When the dynamic voltage unit 222 is turned on, the second diode 224 is turned on, and due to the unidirectional conductivity of the first diode 223, the dynamic voltage is prevented from flowing to the power supply voltage unit 221. At this time, the voltage received by the sensor 21 is the dynamic voltage.

[0086] According to the embodiment of the present disclosure, the dynamic voltage unit 222 adopts a periodic start-stop operation mode, and the dynamic voltage received by the sensor 21 changes periodically. When the dynamic voltage unit 222 is turned off, the sensitive layer 211 is in a low-temperature operation state, and the sensitive gas can diffuse and condense on the sensitive layer 211 by physical adsorption. When the dynamic voltage unit 222 is turned on, the height of the Schottky barrier 217 is significantly reduced. At the same time, the heating module heats the sensitive layer 211 to the target temperature, and the sensitive gas in the volatile organic matter undergoes an oxidation-reduction reaction on the sensitive layer 211. The generated electrons 216 are more easily diffused from the sensitive layer 211 to the two electrodes 212 to achieve signal amplification. At the same time, the dielectric relaxation process can enhance the selectivity of the sensor 21 to the sensitive gas in the volatile organic matter, and provide multi-dimensional output.

[0087] According to the embodiments of the present disclosure, compared with other low-concentration volatile organic compound (VOC) gas detections, the method of modulating the Schottky barrier 217 using the dynamic voltage of the dynamic voltage unit 222 has the advantages of simple implementation, low cost and high return, and can improve the universality of current commercial metal oxide semiconductors, making them suitable for detecting ultra-low volatile organic compound gas concentrations in indoor environments, for example, detecting ultra-low concentrations of VOCs gases such as toluene and acetaldehyde indoors.

[0088] According to the embodiment of the present disclosure, the size of the detection signal output by the sensor 21 is related to the concentration of volatile organic compounds (VOCs). The greater the concentration, the greater the detection signal generated. However, the concentration of the mixed gas containing sensitive gases in the room is low, and the detection signal generated is small, so the detection signal needs to be amplified.

[0089] According to an embodiment of the present disclosure, the detection component 2 further includes at least one amplifying circuit 4. Each amplifying circuit 4 is adapted to amplify a detection signal output by a sensor 21.

[0090] According to the embodiment of the present disclosure, multiple sensors 21 can share one amplifier circuit 4. After each sensor 21 is configured with an amplifier circuit 4, the sensitive gas is pre-enriched on the sensitive layer 211 through a static process, and the responses of the transient process and the non-static process of the sensor 21 are extracted to form a detection signal, thereby improving the response and detection accuracy of the sensor 21. The sensor 21 configured with the amplifier circuit 4 can detect and identify extremely low concentrations of volatile organic compound gases in the room, meeting actual use requirements.

[0091] According to an embodiment of the present disclosure, each amplifier circuit 4 includes a load resistor 41 and an operational amplifier 42, and the sensor response formula of the amplifier circuit 4 is expressed by the following formula (4):

[0092] (4);

[0093] in, It is represented as the response of the sensor 21 in the mixed gas containing the sensitive gas, Expressed as supply voltage, Expressed as a dynamic voltage, It is represented by the output voltage of the sensor 21 in the mixed gas containing the sensitive gas, It is represented as the output voltage of sensor 21 in clean air, It is represented as a load resistor 41.

[0094] According to the embodiment of the present disclosure, the load resistor 41 can be welded to the substrate 1 by welding, and the detection component 2 can be connected to the substrate 1 by hot plugging, so as to facilitate later repair and maintenance.

[0095] According to an embodiment of the present disclosure, the amplification factor of the amplifier circuit 4 is expressed by the following formula (5):

[0096] (5);

[0097] Where q represents the elementary charge, represents the barrier height of Schottky barrier 217, K represents the Boltzmann constant, T represents the temperature, , It is represented by the reduction in the Schottky barrier 217 after the dynamic voltage is applied.

[0098] According to an embodiment of the present disclosure, the signal processing component 3 includes an analog-to-digital conversion unit 31, a data transmission unit 32, and a calculation unit. The analog-to-digital conversion unit 31 is disposed on the substrate 1 and is configured to convert each detection signal into a digital signal. The data transmission unit 32 is disposed on the substrate 1 and is configured to transmit multiple digital signals. The calculation unit is communicatively connected to the data transmission unit 32 and is configured to receive and calculate based on the digital signal to obtain the concentration of the sensitive gas in the volatile organic compound.

[0099] According to an embodiment of the present disclosure, the data transmission unit 32 is electrically connected to the analog-to-digital conversion unit 31, and the data transmission unit 32 is configured to send multiple digital signals to a host computer or upload them to the cloud based on the Internet of Things technology. The multiple digital signals are finally received by the computing unit, and the computing unit can be selected, for example, as a mobile device, and the mobile device includes but is not limited to a desktop computer, a laptop computer, a tablet computer or a CPU, etc.

[0100] According to an embodiment of the present disclosure, the data transmission unit 32 may include a single-chip microcomputer and a data transmission module matched with the single-chip microcomputer. For example, if the computing unit is a laptop computer, the laptop computer may be connected to the data transmission module by serial communication, and the detection signal transmitted to the single-chip microcomputer may be transmitted to the laptop computer through the data transmission module.

[0101] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure, and the shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present disclosure.

[0102] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can be changed according to the desired properties obtained by the content of the present disclosure. Specifically, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include changes in some embodiments of ±10%, in some embodiments of ±5%, in some embodiments of ±1%, and in some embodiments of ±0.5% by a specific number.

[0103] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0104] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0105] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A gas detection device based on barrier modulation, wherein: include: substrate; A detection component is disposed on the substrate and is suitable for detecting volatile organic compounds and outputting a detection signal. The detection component includes: Sensors, including: A substrate, disposed on the heating module; Two electrodes are arranged on the substrate at intervals; A sensitive layer, disposed on the substrate and located between the two electrodes, wherein a Schottky barrier is formed between the two electrodes and the sensitive layer; and a heating module, adapted to heat the sensitive layer through the substrate; a power supply module configured to supply power to the detection component in a manner of alternating operation in a first operation mode and a second operation mode, wherein when the power supply module operates in the first operation mode, the sensitive gas in the volatile organic compound is enriched on the sensitive layer by physical adsorption, and when the power supply module operates in the second operation mode, the height of the Schottky barrier is reduced, and the heating module heats the sensitive layer to a target temperature, so that the sensitive gas in the volatile organic compound undergoes an oxidation-reduction reaction on the sensitive layer to generate electrons and generate the detection signal; and The signal processing component is arranged on the substrate and is suitable for receiving and obtaining the concentration of the sensitive gas according to the detection signal.

2. The gas detection device according to claim 1, wherein: During the process of the heating module heating the sensitive layer to the target temperature, the sensitive gas enriched on the sensitive layer is continuously consumed, so that the generated electrons are reduced, and the sensor enters a dielectric relaxation process.

3. The gas detection device according to claim 2, wherein: The sensor is provided in a plurality, and the sensitive layer of each sensor matches a different sensitive gas in the volatile organic compound to generate different detection signals respectively; Wherein, different sensitive gases have different activation energies, so that different sensitive layers respectively matched with different sensitive gases have different voltage drop trends in the dielectric relaxation process.

4. The gas detection device according to claim 1, wherein: The material of the sensitive layer is a metal oxide with a granular structure, gaps are formed between the granular structures, and the sensitive gas penetrates into the gaps and diffuses evenly when the power supply module is in the first operating mode.

5. The gas detection device according to claim 1, wherein: The power supply module comprises: a supply voltage unit configured to maintain the sensitive gas enriched on the sensitive layer; A first diode connected in series with the power supply voltage unit; a dynamic voltage unit connected in parallel with the power supply voltage unit; and A second diode connected in series with the dynamic voltage unit; The first diode and the second diode are respectively configured to be turned on or off according to the working state of the dynamic voltage unit, so that the voltage received by the sensor is periodically switched.

6. The gas detection device according to claim 5, wherein: The first operation mode is that when the dynamic voltage unit is turned off, the first diode is turned on, the second diode is turned off, and the voltage received by the sensor is the supply voltage; The second operation mode is that when the dynamic voltage unit is turned on, the first diode is turned off, the second diode is turned on, and the voltage received by the sensor is a dynamic voltage.

7. The gas detection device according to claim 1, wherein: The detection component also includes: At least one amplifying circuit, each of the amplifying circuits is adapted to amplify the detection signal output by one of the sensors.

8. The gas detection device according to claim 7, wherein: Each of the amplifying circuits comprises a load resistor and an operational amplifier, and the sensor response formula of the amplifying circuit is: ; in, It is expressed as the response of the sensor in a mixed gas containing the sensitive gas, Expressed as the supply voltage, Expressed as the dynamic voltage, It is expressed as the output voltage of the sensor in a mixed gas containing the sensitive gas, It is represented as the output voltage of the sensor in clean air, Indicated as the load resistance.

9. The gas detection device according to claim 8, wherein: The amplification factor of the amplifier circuit is: ； Where q represents the elementary charge, represents the barrier height of the Schottky barrier, K represents the Boltzmann constant, T represents the temperature, , It is expressed as the reduction of the Schottky barrier after applying the dynamic voltage.

10. The gas detection device according to any one of claims 1 to 9, wherein: The signal processing component comprises: an analog-to-digital conversion unit, disposed on the substrate and configured to convert each detection signal into a digital signal; a data transmission unit, disposed on the substrate, configured to transmit a plurality of the digital signals; and The calculation unit is communicatively connected with the data transmission unit and is configured to receive and perform calculation according to the digital signal to obtain the concentration of the sensitive gas in the volatile organic compound.

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