A gas concentration sensor

Abstract

The application discloses a gas concentration sensor, which comprises a detection resistor, an outer surface of which is uniformly covered with an oxidation catalyst; a trigger circuit, which controls the contact of the to-be-detected gas with the oxidation catalyst when the concentration of the to-be-detected gas exceeds a concentration threshold and lasts for a first preset time period, and the resistance of the detection resistor linearly changes according to the concentration of the to-be-detected gas; a thermosensitive compensation resistor, which adjusts its resistance according to the temperature of the to-be-detected gas; a first parallel node is arranged between the detection resistor and the thermosensitive compensation resistor; a resistance detection circuit, which detects the total resistance on the parallel node; a power amplification circuit, which amplifies the power signal flowing through the parallel node to obtain a power amplification signal; and a voltage stabilizing circuit, which stabilizes the power amplification signal and outputs the standard value of the power amplification signal in a second preset time period as an output signal when the change amplitude of the power amplification signal in the second preset time period is less than a change threshold. The application improves the stability of the output signal of the gas concentration sensor.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and more particularly to a gas concentration sensor. Background Technology

[0002] Gas sensors are needed to identify, detect, measure, and confirm the presence of gases in industrial environments. Based on the volume and concentration of the gas in the area, the gas sensor generates a corresponding potential difference, which changes the resistance of the sensor's internal materials. This change in resistance generates an electrical signal, which is ultimately measured as the output voltage. Gas concentration sensors are used to detect gas concentrations in various scenarios. Currently, existing gas concentration sensors, during use, suffer from constantly changing gas concentrations detected in real time. Furthermore, influenced by the internal circuitry of the sensor, the output signal also fluctuates rapidly, which can negatively impact subsequent signal control. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a gas concentration sensor to improve the stability of the output signal of the gas concentration sensor.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a gas concentration sensor, comprising:

[0005] The detector has a resistance rating, and its outer surface is uniformly covered with an oxidation catalyst.

[0006] A trigger circuit, with its output terminal connected to the detection resistor, is used to control the gas to be tested to contact the oxidation catalyst when the concentration of the gas to be tested exceeds the concentration threshold and continues for a first preset time period. The resistance value of the detection resistor changes linearly according to the concentration of the gas to be tested.

[0007] A thermistor, connected in series with the detection resistor, is used to adjust its resistance value according to the temperature of the gas to be measured. A first parallel node is provided between the detection resistor and the thermistor.

[0008] The resistance detection circuit has an input terminal connected to the first parallel node and an output terminal connected to a variable resistor, used to detect the total resistance value on the parallel node. The first parallel node is also connected to a power amplifier circuit, which is used to amplify the power signal flowing through the parallel node to obtain a power amplified signal.

[0009] A voltage regulator circuit, with its input terminal connected to the power amplifier circuit, is used to regulate the voltage of the power amplifier signal and calculate the standard value of the power amplifier signal within the second preset time period as the output signal when the change amplitude of the power amplifier signal within the second preset time period is less than the change threshold.

[0010] Furthermore, the oxidation catalyst is externally provided with an openable and closable sealing mechanism, and the trigger circuit includes:

[0011] The trigger resistor has a uniform outer surface covered with a luminescent reactant. When the concentration of the gas to be tested exceeds the concentration threshold, the luminescent reactant reacts with the gas to be tested in a chemiluminescent reaction.

[0012] A photodetector branch is located near the trigger resistor and is used to generate a trigger signal based on the light intensity during the chemiluminescence reaction.

[0013] The first timer branch, with its input terminal connected to the optical detection branch, is used to start timing after receiving the trigger signal and generate a first timing time.

[0014] The first control branch has its input end connected to the first timer branch and its output end connected to the sealing mechanism. It is used to generate an opening signal when the first timing time reaches the first preset time period. The sealing mechanism opens according to the opening command so that the gas to be tested comes into contact with the oxidation catalyst.

[0015] Furthermore, the optical detection branch includes:

[0016] A photodiode is positioned directly opposite the trigger resistor and maintains a first preset distance from the trigger resistor. It is used to adjust its own resistance according to the light intensity, and the photocurrent signal flowing through the photodiode is adjusted accordingly.

[0017] An operational amplifier, with its input terminal connected to the photodiode, is used to amplify and convert the adjusted photocurrent signal to obtain a voltage amplified signal.

[0018] A Schmitt trigger, with its input connected to the operational amplifier, is used to generate the trigger signal when the voltage amplification signal is greater than a preset positive threshold voltage.

[0019] Furthermore, the voltage regulator circuit includes:

[0020] The first voltage regulation branch is connected to the power amplifier circuit at its input terminal, and is used to reduce the high-frequency power gain in the power amplified signal.

[0021] The second voltage regulator branch, whose input is connected to the first voltage regulator branch, is used to reduce the low-frequency power gain in the power amplified signal.

[0022] The second timer branch, with its input terminal connected to the second voltage regulator branch, is used to start timing after the power amplification signal sequentially reduces the high-frequency power gain and the low-frequency power gain, thereby generating a second timing time.

[0023] The second control branch, whose input is connected to the second timer branch, is used to continuously count the change amplitude of the power amplification signal after the second timer branch starts timing, and to calculate and output the standard value of the power amplification signal within the second preset time period when the length of the second timing period does not reach the second preset time period and the change amplitude is less than the change threshold.

[0024] Furthermore, the first voltage stabilizing branch includes:

[0025] The first field-effect transistor H1 is configured with a first gate, a first source and a first drain. The first source is grounded, the first gate is connected to a first resistor R1, the other end of the first resistor R1 is connected to a first capacitor C1, and the other end of the first capacitor C1 is connected to the first drain.

[0026] A first input node is provided between the first gate and the first resistor R1, and the first input node is the input terminal of the first voltage regulation branch. A first output node is provided between the first capacitor C1 and the first drain, and the first output node is the output terminal of the first voltage regulation branch.

[0027] Furthermore, the second voltage stabilizing branch includes:

[0028] The second field-effect transistor H2 is configured with a second gate, a second source, and a second drain. The second source is grounded, and the second gate is connected to the first output node. The second gate is the input terminal of the second voltage regulator branch. The second drain is connected to a first inductor L1. The other end of the first inductor L1 is connected to a second parallel node. The second parallel node is connected to a second inductor L2 and a second resistor R2 connected in parallel. The other ends of the second inductor L2 and the second resistor R2 are connected to ground in parallel. The second parallel node is the output terminal of the second voltage regulator branch.

[0029] Furthermore, the second control branch includes a control chip, the control chip comprising:

[0030] Storage unit, used to continuously store the power amplification signal during the second timing period;

[0031] A difference unit, connected to the storage unit, is used to calculate the difference between the power amplified signals at each adjacent time point to obtain the change amplitude.

[0032] The comparison unit, connected to the difference unit, is used to compare the length of the second timing time with the second preset time period and to compare the change amplitude with the change threshold. When the length of the second timing time does not reach the second preset time period and the change amplitude is less than the change threshold, a calculation instruction is generated.

[0033] The calculation unit, connected to the comparison unit, is used to input each of the power amplified signals within the second preset time period into a preset calculation formula according to the calculation instruction, obtain the standard value, and output it.

[0034] Furthermore, a filtering circuit is included, disposed between the power amplifier circuit and the voltage regulator circuit, with its input terminal connected to the power amplifier circuit and its output terminal connected to the voltage regulator circuit, for filtering noise in the power amplifier signal and inputting the filtered power amplifier signal into the voltage regulator circuit.

[0035] Furthermore, it also includes a power supply circuit, with the two ends of the variable resistor connected in parallel with the power supply circuit. The two ends of the power supply circuit are also connected to the trigger circuit, the filter circuit, the voltage regulator circuit, and the power amplifier circuit, for supplying power to the trigger circuit, the filter circuit, the voltage regulator circuit, and the power amplifier circuit, respectively.

[0036] Furthermore, the length, width, and height of the detection resistor do not exceed 1 mm.

[0037] The beneficial effects of this invention are:

[0038] This invention first incorporates a trigger circuit that ensures the oxidation catalyst only comes into contact with the gas after the concentration of the gas to be measured exceeds a concentration threshold and remains so for a first preset time period. This not only extends the lifespan of the oxidation catalyst but also filters out low-concentration gas data with short durations that do not require detection, laying the foundation for a stable output signal. Furthermore, this invention utilizes a combination of a thermistor and a variable resistor to eliminate the influence and deviation caused by changes in ambient temperature on the resistance value of the detection resistor, improving detection accuracy. Finally, this invention employs a voltage regulator circuit to repeatedly regulate the power amplified signal and outputs a standard value calculated when the amplitude of the power amplified signal's variation within a second preset time period is stabilized within a threshold range, effectively enhancing the stability of the output signal. Attached Figure Description

[0039] Figure 1 This is a control principle diagram of the gas concentration sensor in this invention;

[0040] Figure 2 This is the circuit diagram of the first voltage-stabilizing branch in this invention;

[0041] Figure 3 This is the circuit diagram of the second voltage-stabilizing branch in this invention.

[0042] Reference numerals: 1. Detection resistor; 11. Oxidation catalyst; 12. Sealing mechanism; 2. Trigger circuit; 21. Trigger resistor; 22. Photodetector branch; 221. Photoconversion diode; 222. Operational amplifier; 223. Schmitt trigger; 23. First timer branch; 24. First control branch; 3. Thermistor; 4. Resistance detection circuit; 5. Variable resistor; 6. Power amplifier circuit; 7. Voltage regulator circuit; 71. First voltage regulator branch; 72. Second voltage regulator branch; 73. Second control branch; 731. Storage unit; 732. Difference unit; 733. Comparison unit; 734. Calculation unit; 8. Filtering circuit; 9. Power supply circuit. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Identical components are denoted by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to directions in the accompanying drawings, and the terms "bottom surface," "top surface," "inner," and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0044] like Figure 1 As shown, a gas concentration sensor according to this embodiment includes:

[0045] The detection resistor 1 has an outer surface uniformly covered with an oxidation catalyst 11;

[0046] Trigger circuit 2, with its output terminal connected to the detection resistor 1, is used to control the gas to be tested to contact the oxidation catalyst 11 when the concentration of the gas to be tested exceeds the concentration threshold and continues for a first preset time period. The resistance value of the detection resistor 1 changes linearly according to the concentration of the gas to be tested.

[0047] Thermistor 3 is connected in series with the detection resistor 1 and is used to adjust its resistance value according to the temperature of the gas to be measured. A first parallel node is provided between the detection resistor 1 and thermistor 3.

[0048] The resistance detection circuit 4 has its input end connected to the first parallel node and its output end connected to a variable resistor 5, which is used to detect the total resistance value on the parallel node. The first parallel node is also connected to a power amplifier circuit 6, which is used to amplify the power signal flowing through the parallel node to obtain a power amplified signal.

[0049] The voltage regulator circuit 7 is connected to the power amplifier circuit 6 at its input terminal. It is used to regulate the voltage of the power amplifier signal and calculate the standard value of the power amplifier signal in the second preset time period as the output signal when the change amplitude of the power amplifier signal in the second preset time period is less than the change threshold.

[0050] Specifically, in this embodiment, a trigger circuit 2 is first set up so that the oxidation catalyst 11 only comes into contact with the gas to be tested after the concentration of the gas to be tested exceeds the concentration threshold and remains so for a first preset time period. This not only extends the service life of the oxidation catalyst 11, but also filters out some low-concentration gas data that do not need to be detected and have a short duration of concentration, laying the foundation for a stable output signal. In this embodiment, the first preset time period can be 3 seconds, and the concentration threshold can be 2%, both of which can be adjusted according to the actual environment.

[0051] This technical solution also eliminates the influence and deviation of ambient temperature changes on the resistance value of the detection resistor 1 by cooperating with the thermistor 3 and the variable resistor 5, thereby improving the detection accuracy. This technical solution also improves the stability of the output signal by setting a voltage regulator circuit 7 to perform multiple voltage regulation on the power amplification signal, and outputs the standard value calculated when the change amplitude of the power amplification signal is stabilized within the change threshold range in the second preset time period.

[0052] Working principle:

[0053] In this technical solution, the oxidation catalyst 11 undergoes a vigorous oxidation reaction upon contact with the gas to be tested. Depending on the gas to be tested, the oxidation catalyst 11 can be replaced to achieve accurate and reliable detection. The detection resistor 1 is essentially a thermistor, and the gas to be tested is a combustible gas. When the gas to be tested comes into contact with the oxidation catalyst 11, a vigorous oxidation reaction occurs, initiating combustion and generating heat. This heat causes a temperature change on the outer surface of the detection resistor 1, which is detected by the detection resistor 1. The resistance of the detection resistor 1 changes accordingly with the temperature change, and the resistance of the detection resistor 1 is linearly positively correlated with the concentration of the gas to be tested. Simultaneously, the thermistor compensation resistor 3 is located in a close region to the detection resistor 1. The thermistor compensation resistor 3 detects the ambient temperature and adjusts its resistance according to the ambient temperature. The variable resistor 5 moves accordingly with the change in the thermistor compensation resistor 3, eliminating the deviation of the total resistance value measured by the resistance detection circuit 4 due to changes in ambient temperature. In this embodiment, the heat generated by combustion on the surface of the detection resistor 1 does not affect the temperature change around the compensation resistor.

[0054] Preferably, the oxidation catalyst 11 is externally provided with an openable and closable sealing mechanism 12, and the trigger circuit 2 includes:

[0055] The trigger resistor 21 has a uniform outer surface covered with a luminescent reactant. When the concentration of the gas to be tested exceeds the concentration threshold, the luminescent reactant reacts with the gas to be tested to produce a chemiluminescence reaction.

[0056] The photodetector branch 22 is located near the trigger resistor 21 and is used to generate a trigger signal based on the light intensity during the chemiluminescence reaction.

[0057] The first timer branch 23 has its input terminal connected to the light detection branch 22, and is used to start timing after receiving a trigger signal to generate the first timing time;

[0058] The first control branch 24 has its input end connected to the first timer branch 23 and its output end connected to the sealing mechanism 12. It is used to generate an opening signal when the first timing time reaches the first preset time period. The sealing mechanism 12 opens according to the opening command so that the gas to be tested can come into contact with the oxidation catalyst 11.

[0059] Specifically, in this embodiment, the first control branch 24 can be a control chip, specifically an STM32L433RBT6. The sealing mechanism 12 is configured to open and close according to the instructions of the control chip, thereby establishing a mechanical structure to determine whether the gas to be tested is in contact with the surface of the detection resistor 1. When the first timing period reaches 3 seconds, it indicates that the gas concentration exceeds 2% and has lasted for 3 seconds. At this time, the sealing mechanism 12 is opened to allow the gas to be tested to contact the oxidation catalyst 11 and change the resistance value of the resistor to be tested. When the gas concentration does not exceed 2% and the duration exceeds 3 seconds, the control chip generates a shutdown command, and the sealing mechanism 12 automatically closes according to the shutdown command, so that the external gas to be tested no longer continuously contacts the oxidation catalyst 11, avoiding the oxidation catalyst 11 from continuously failing and saving costs.

[0060] Preferably, the optical detection branch 22 includes:

[0061] A photodiode 221 is positioned directly opposite a trigger resistor 21 and maintains a first preset distance from the trigger resistor 21. It is used to adjust its own resistance value according to the light intensity, and the photocurrent signal flowing through the photodiode 221 is adjusted accordingly.

[0062] Operational amplifier 222, with its input terminal connected to photodiode 221, is used to amplify and convert the adjusted photocurrent signal to obtain a voltage amplified signal;

[0063] The Schmitt trigger 223, with its input connected to the operational amplifier 222, is used to generate a trigger signal when the voltage amplification signal is greater than a preset positive threshold voltage.

[0064] Specifically, in this embodiment, the photodiode 221 adjusts its resistance according to the light intensity when the trigger resistor 21 undergoes a chemiluminescence reaction, thereby adjusting the photocurrent signal flowing through it. The operational amplifier 222 then amplifies and converts the adjusted photocurrent signal, achieving several-fold amplification and conversion. Finally, when the voltage amplification signal exceeds the forward voltage threshold, the Schmitt trigger 223 generates a trigger signal.

[0065] Preferably, the voltage regulator circuit 7 includes:

[0066] The first voltage regulator branch 71 is connected to the power amplifier circuit 6 at its input terminal, and is used to reduce the high-frequency power gain in the power amplified signal.

[0067] The second voltage regulator branch 72 is connected to the first voltage regulator branch 71 at its input terminal and is used to reduce the low-frequency power gain in the power amplification signal.

[0068] The second timer branch, with its input connected to the second voltage regulator branch 72, is used to start timing after the power amplification signal is sequentially reduced in high-frequency power gain and low-frequency power gain, and to generate the second timing time.

[0069] The second control branch 73 is connected to the second timer branch at its input terminal. It is used to continuously count the change amplitude of the power amplification signal after the second timer branch starts timing, and to calculate and output the standard value of the power amplification signal within the second preset time period when the length of the second timing period does not reach the second preset time period and the change amplitude is less than the change threshold.

[0070] Preferred, such as Figure 2 As shown, the first voltage stabilizing branch 71 includes:

[0071] The first field-effect transistor H1 is configured with a first gate, a first source and a first drain. The first source is grounded, the first gate is connected to a first resistor R1, the other end of the first resistor R1 is connected to a first capacitor C1, and the other end of the first capacitor C1 is connected to the first drain.

[0072] A first input node is provided between the first gate and the first resistor R1. The first input node is the input terminal of the first voltage regulation branch 71. A first output node is provided between the first capacitor C1 and the first drain. The first output node is the output terminal of the first voltage regulation branch 71.

[0073] Specifically, in this embodiment, the first voltage regulation branch 71 uses a gate-drain feedback first resistor R1. This reduces the high-frequency power gain, thereby improving the stability of the power amplifier.

[0074] Preferred, such as Figure 3 As shown, the second voltage regulator branch 72 includes:

[0075] The second field-effect transistor H2 is configured with a second gate, a second source, and a second drain. The second source is grounded, and the second gate is connected to the first output node. The second gate is the input terminal of the second voltage regulator branch 72. The second drain is connected to a first inductor L1. The other end of the first inductor L1 is connected to a second parallel node. The second parallel node is connected to a second inductor L2 and a second resistor R2 connected in parallel. The other ends of the second inductor L2 and the second resistor R2 are connected to ground in parallel. The second parallel node is the output terminal of the second voltage regulator branch 72.

[0076] Specifically, in this embodiment, the second voltage regulation branch 72 reduces the low-frequency power gain and Miller effect of the gate-drain feedback capacitance in the power amplified signal by using a second drain connected in parallel with a second resistor R2. Simultaneously, the second field-effect transistor H2 connected in series with the first inductor L1 effectively prevents power loss within the operating frequency bandwidth.

[0077] Preferably, the second control branch 73 includes a control chip, which includes:

[0078] Storage unit 731 is used to continuously store the power amplification signal during the second timing period;

[0079] The difference unit 732 is connected to the storage unit 731 and is used to calculate the difference between the power amplified signals at adjacent time points to obtain the change amplitude.

[0080] The comparison unit 733 is connected to the difference unit 732 and is used to compare the length of the second timing time with the second preset time period and compare the change amplitude with the change threshold. When the length of the second timing time does not reach the second preset time period and the change amplitude is less than the change threshold, a calculation instruction is generated.

[0081] The calculation unit 734 is connected to the comparison unit 733 and is used to input each power amplification signal in the second preset time period into the preset calculation formula according to the calculation instruction to obtain the standard value and output it as the output signal.

[0082] Specifically, in this embodiment, the control chip can be an STM32L433RBT6. The storage unit 731 can be a non-volatile memory container within the control chip, used to continuously store the power amplification signal according to the second timing period of the second timer circuit. The duration of a single time point can be 0.5 seconds. The second preset time can be 2 seconds. The difference unit 732 obtains several sets of variation amplitudes by subtracting the power amplification signals at each adjacent time point. When the length of the second timing period does not reach the second preset time period and the variation amplitude is less than the variation threshold, it indicates that the variation amplitude of the power amplification signal within the second timing period is small, and a standard value can be calculated for stable output. The calculation unit 734, according to the calculation instruction, substitutes each power amplification signal within 2 seconds into the root mean square average calculation formula to obtain the standard value as the output signal. At this time, the output signal has undergone multiple filtering, voltage regulation, range limiting, and calculations, greatly improving its stability.

[0083] Preferably, a filter circuit 8 is included, which is disposed between the power amplifier circuit 6 and the voltage regulator circuit 7. The input terminal is connected to the power amplifier circuit 6, and the output terminal is connected to the voltage regulator circuit 7. It is used to filter out noise in the power amplifier signal and input the filtered power amplifier signal into the voltage regulator circuit 7.

[0084] Specifically, in this embodiment, the filter circuit 8 can be a high-pass filter. By setting a high-pass filter between the power amplifier circuit 6 and the voltage regulator circuit 7, low-frequency interference is filtered out, and the stability of the filtered power amplifier signal is improved.

[0085] Preferably, it also includes a power supply circuit 9, with the two ends of the variable resistor 5 connected in parallel with the power supply circuit 9. The two ends of the power supply circuit 9 are also connected to the trigger circuit 2, the filter circuit 8, the voltage regulator circuit 7, and the power amplifier circuit 6, for supplying power to the trigger circuit 2, the filter circuit 8, the voltage regulator circuit 7, and the power amplifier circuit 6, respectively.

[0086] Specifically, in this embodiment, the power supply circuit 9 can be a DC power supply, and the voltage range of the DC power supply to each circuit can be from 5V to 24V.

[0087] Preferably, the length, width, and height of the detection resistor 1 do not exceed 1 mm.

[0088] Specifically, in this embodiment, since the concentration of the gas to be tested is generally very low, the heat generated by combustion when it reacts with the oxidation catalyst 11 is also very small. In order to improve the detection accuracy, the size of the detection resistor 1 is designed to be very small, so that its length, width and height are all no more than 1 mm. By setting it in this way, even a small amount of heat can cause a temperature change and thus be detected.

[0089] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A gas concentration sensor, characterized in that, include: The detection resistor (1) has an outer surface uniformly covered with an oxidation catalyst (11); The trigger circuit (2) is connected to the detection resistor (1) at its output terminal. It is used to control the gas to be tested to contact the oxidation catalyst (11) when the concentration of the gas to be tested exceeds the concentration threshold and continues for a first preset time period. The resistance value of the detection resistor (1) changes linearly according to the concentration of the gas to be tested. A thermistor (3) is connected in series with the detection resistor (1) and is used to adjust its resistance value according to the temperature of the gas to be tested. A first parallel node is provided between the detection resistor (1) and the thermistor (3). The resistance detection circuit (4) has its input end connected to the first parallel node and its output end connected to a variable resistor (5), which is used to detect the total resistance on the parallel node. The first parallel node is also connected to a power amplifier circuit (6), which is used to amplify the power signal flowing through the parallel node to obtain a power amplified signal. The voltage regulator circuit (7) is connected to the power amplifier circuit (6) at its input terminal. It is used to regulate the power amplifier signal and calculate the standard value of the power amplifier signal in the second preset time period as the output signal when the change amplitude of the power amplifier signal in the second preset time period is less than the change threshold. The oxidation catalyst (11) is externally provided with an openable and closable sealing mechanism (12), and the trigger circuit (2) includes: The trigger resistor (21) has a uniform outer surface covered with a luminescent reactant. When the concentration of the gas to be tested exceeds the concentration threshold, the luminescent reactant reacts with the gas to be tested in a chemiluminescent reaction. The photodetector branch (22) is located near the trigger resistor (21) and is used to generate a trigger signal based on the light intensity during the chemiluminescence reaction. The first timer branch (23) is connected to the light detection branch (22) at its input end, and is used to start timing after receiving the trigger signal to generate a first timing time; The first control branch (24) is connected to the first timer branch (23) at its input end and to the sealing mechanism (12) at its output end. It is used to generate an opening signal when the length of the first timing time reaches the first preset time period. The sealing mechanism (12) is opened according to the opening command so that the gas to be tested comes into contact with the oxidation catalyst (11).

2. The gas concentration sensor according to claim 1, characterized in that: The optical detection branch (22) includes: A photodiode (221) is positioned opposite the trigger resistor (21) and maintains a first preset distance from the trigger resistor (21). It is used to adjust its own resistance according to the light intensity, and the photocurrent signal flowing through the photodiode (221) is adjusted accordingly. An operational amplifier (222) with its input terminal connected to the photodiode (221) is used to amplify and convert the adjusted photocurrent signal to obtain a voltage amplified signal. A Schmitt trigger (223) is connected to the operational amplifier (222) at its input terminal, and is used to generate the trigger signal when the voltage amplification signal is greater than a preset positive threshold voltage.

3. The gas concentration sensor according to claim 1, characterized in that: The voltage regulator circuit (7) includes: The first voltage regulator branch (71) is connected to the power amplifier circuit (6) at its input terminal, and is used to reduce the high-frequency power gain in the power amplified signal; The second voltage regulator branch (72) is connected to the first voltage regulator branch (71) at its input end, and is used to reduce the low-frequency power gain in the power amplified signal. The second timer branch, with its input terminal connected to the second voltage regulator branch (72), is used to start timing after the power amplification signal successively reduces the high-frequency power gain and the low-frequency power gain, and generate a second timing time. The second control branch (73) is connected to the second timer branch at its input end. It is used to continuously count the change amplitude of the power amplification signal after the second timer branch starts timing, and to calculate and output the standard value of the power amplification signal within the second preset time period when the length of the second timing period does not reach the second preset time period and the change amplitude is less than the change threshold.

4. The gas concentration sensor according to claim 3, characterized in that: The first voltage stabilizing branch (71) includes: The first field-effect transistor H1 is configured with a first gate, a first source and a first drain. The first source is grounded, the first gate is connected to a first resistor R1, the other end of the first resistor R1 is connected to a first capacitor C1, and the other end of the first capacitor C1 is connected to the first drain. A first input node is provided between the first gate and the first resistor R1. The first input node is the input terminal of the first voltage regulator branch (71). A first output node is provided between the first capacitor C1 and the first drain. The first output node is the output terminal of the first voltage regulator branch (71).

5. The gas concentration sensor according to claim 4, characterized in that: The second voltage stabilizing branch (72) includes: The second field-effect transistor H2 is configured with a second gate, a second source, and a second drain. The second source is grounded, and the second gate is connected to the first output node. The second gate is the input terminal of the second voltage regulator branch (72). The second drain is connected to a first inductor L1. The other end of the first inductor L1 is connected to a second parallel node. The second parallel node is connected to a second inductor L2 and a second resistor R2 connected in parallel. The other ends of the second inductor L2 and the second resistor R2 are connected to ground in parallel. The second parallel node is the output terminal of the second voltage regulator branch (72).

6. The gas concentration sensor according to claim 3, characterized in that: The second control branch (73) includes a control chip, the control chip comprising: Storage unit (731) is used to continuously store the power amplification signal during the second timing period; The difference unit (732) is connected to the storage unit (731) and is used to obtain the change amplitude by subtracting the power amplified signals at each adjacent time point; The comparison unit (733) is connected to the difference unit (732) and is used to compare the length of the second timing time with the second preset time period and compare the change amplitude with the change threshold. When the length of the second timing time does not reach the second preset time period and the change amplitude is less than the change threshold, a calculation instruction is generated. The calculation unit (734) is connected to the comparison unit (733) and is used to input each of the power amplification signals in the second preset time period into a preset calculation formula according to the calculation instruction to obtain the standard value and output it.

7. The gas concentration sensor according to claim 1, characterized in that: It also includes a filter circuit (8), which is disposed between the power amplifier circuit (6) and the voltage regulator circuit (7). The input terminal is connected to the power amplifier circuit (6), and the output terminal is connected to the voltage regulator circuit (7). It is used to filter out noise in the power amplifier signal and input the filtered power amplifier signal into the voltage regulator circuit (7).

8. The gas concentration sensor according to claim 7, characterized in that: It also includes a power supply circuit (9), with the two ends of the variable resistor (5) connected in parallel with the power supply circuit (9). The two ends of the power supply circuit (9) are also connected to the trigger circuit (2), the filter circuit (8), the voltage regulator circuit (7) and the power amplifier circuit (6), for supplying power to the trigger circuit (2), the filter circuit (8), the voltage regulator circuit (7) and the power amplifier circuit (6) respectively.

9. The gas concentration sensor according to claim 1, characterized in that: The length, width, and height of the detection resistor (1) do not exceed 1 mm.

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