A method and system for detecting the gas concentration of acetylene

Abstract

The application discloses a kind of gas concentration detection method and system for acetylene, belong to gas detection technical field, the method is applied to including oscillating arm and composite sensitized film quartz tuning fork;Composite sensitized film is coated in the side of oscillating arm;The method includes to quartz tuning fork is applied sweep excitation, obtains current resonance frequency;Quartz tuning fork is placed in the acetylene environment to be measured, and time sequence resonance frequency is obtained;According to current resonance frequency control drive laser irradiation acetylene environment to be measured, to obtain time sequence piezoelectric signal;According to time sequence resonance frequency obtains first gas concentration and according to time sequence piezoelectric signal obtains second gas concentration;According to time sequence resonance frequency, first gas concentration, time sequence piezoelectric signal and second gas concentration obtain the target gas concentration of acetylene environment to be measured.Therefore, by implementing the present application, the technical problem that prior art cannot accurately, quickly detect acetylene concentration can be solved, for improving the precision of detection.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a method and system for detecting the gas concentration of acetylene. Background Technology

[0002] Quartz tuning forks are widely used in gas detection due to their advantages such as high stability, high quality factor, low cost, and ease of integration. In existing technologies for acetylene gas detection using quartz tuning forks, two main detection schemes have been developed: The first type of approach uses a laser to excite the gas to be tested, generating photoacoustic waves that drive a tuning fork to resonate. The gas concentration is then deduced by measuring the electrical signal output by the tuning fork. This type of approach is limited by the low photoacoustic conversion efficiency of acetylene molecules at room temperature, resulting in weak signal amplitude. It often requires complex lasers, optical path alignment, and frequency matching systems for auxiliary detection, making it difficult to implement in engineering.

[0003] The second type of scheme directly utilizes the characteristic that the resonant frequency of a quartz tuning fork drifts with changes in surface adsorption mass, and achieves gas detection by measuring the frequency shift. However, under complex background atmospheres or environmental disturbances, the frequency drift of this type of scheme is easily affected by factors such as non-target adsorption and changes in temperature and humidity. The reliability of a single criterion is insufficient, resulting in low accuracy of the obtained detection results. Summary of the Invention

[0004] This invention provides a method and system for detecting acetylene gas concentration, which can solve the technical problem of difficulty in accurately and quickly detecting acetylene concentration in the prior art, and improve the accuracy of detection.

[0005] To address the aforementioned technical problems, this invention discloses a method for detecting acetylene gas concentration, applied to a quartz tuning fork; the quartz tuning fork includes vibrating arms and a composite sensitizing film; wherein any two adjacent vibrating arms are arranged opposite each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitizing film covers the side; the gas concentration detection method includes: A frequency sweep excitation is applied to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork; The quartz tuning fork is placed in the acetylene environment to be tested in order to obtain the timing resonant frequency of the quartz tuning fork. The driving laser is modulated according to the current resonant frequency, and the driving laser is controlled to irradiate the acetylene environment to be tested, so as to obtain the timing piezoelectric signal of the quartz tuning fork; The first gas concentration of the acetylene environment to be tested is obtained according to the time-series resonant frequency, and the second gas concentration of the acetylene environment to be tested is obtained according to the time-series piezoelectric signal. The target gas concentration of the acetylene environment to be tested is obtained based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration.

[0006] This invention discloses a method for detecting acetylene gas concentration. A sweep frequency excitation is applied to a quartz tuning fork coated with a composite sensitized film (the film is disposed on the opposite sides of the two vibrating arms). The output piezoelectric signal is demodulated and fitted to obtain the current resonant frequency reflecting the initial state of the tuning fork. The tuning fork is placed in the acetylene environment to be tested, and the sweep frequency response is continuously demodulated and fitted to obtain the time-series resonant frequency reflecting the dynamic adsorption process of acetylene. Based on the current resonant frequency, a driving laser is modulated to control the laser irradiation of the environment to be tested and the second harmonic demodulation of the piezoelectric signal output by the tuning fork is performed to obtain the time-series piezoelectric signal reflecting the photoacoustic intensity. The time-series resonant frequency is frequency drift calculated and calibrated to obtain a first gas concentration. The time-series piezoelectric signal is amplitude calibrated to obtain a second gas concentration. Finally, the time-series resonant frequency, the first gas concentration, the time-series piezoelectric signal, and the second gas concentration are subjected to consistency judgment and fusion processing to obtain the target gas concentration. The method disclosed in this invention achieves complementary detection through dual physical mechanisms by simultaneously acquiring and fusing two independent signals, electrical and photoacoustic, on the same composite sensitized quartz tuning fork. It utilizes both the efficient adsorption mass loading effect of the sensitized film on acetylene and the enhancement effect of the composite structure on photoacoustic relaxation, thereby improving the overall accuracy and environmental adaptability of acetylene concentration detection.

[0007] As a preferred example, applying a frequency sweep excitation to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork includes: The quartz tuning fork is placed in a zero-air environment, and a preset sinusoidal sweep voltage signal is applied to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. The current piezoelectric current signal is converted into a current piezoelectric voltage signal, and the current piezoelectric voltage signal is phase-sensitively demodulated according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; The amplitude-frequency response curve is subjected to Lorentz fitting to obtain the fitted curve, and the center frequency of the fitted curve is taken as the current resonant frequency of the quartz tuning fork.

[0008] The above scheme applies a sinusoidal sweep voltage signal to a quartz tuning fork placed in a zero-gas environment. The acquired piezoelectric current signal is then converted from current to voltage. Phase-sensitive demodulation is performed on the voltage signal based on the instantaneous frequency of the sweep voltage to obtain an amplitude-frequency response curve reflecting the frequency-amplitude relationship. This curve is then Lorentz-fitted to obtain the center frequency of the fitted curve as the current resonant frequency. By performing phase-sensitive demodulation and Lorentz-fitting on the sweep response data, a precise reference frequency is obtained, thus achieving high-precision self-calibration of the tuning fork's resonant frequency under acetylene interference-free conditions, providing a stable reference zero point for subsequent frequency drift measurements.

[0009] As a preferred example, placing the quartz tuning fork in the acetylene environment to be tested to obtain the timing resonant frequency of the quartz tuning fork includes: The signal amplitude of the sinusoidal sweep voltage signal and the predicted acetylene concentration of the acetylene environment to be tested are obtained, so as to find out the maximum frequency drift corresponding to the predicted acetylene concentration. The current resonant frequency is used as the frequency center, and the sweep frequency range is determined based on the frequency center and the maximum frequency drift. A real-time sinusoidal sweep voltage signal is generated based on the signal amplitude and the sweep frequency range, and the real-time sinusoidal sweep voltage signal is applied to the excitation pin to obtain the real-time piezoelectric current signal output by the quartz tuning fork. The real-time piezoelectric current signal is converted into a real-time piezoelectric voltage signal, and the real-time piezoelectric voltage signal is demodulated in a phase-sensitive manner according to the instantaneous sweep frequency of the real-time sinusoidal sweep voltage signal to obtain a real-time amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Lorentz fitting is performed on the real-time amplitude-frequency response curve to obtain the real-time fitted curve, and the center frequency of the real-time fitted curve is taken as the real-time resonant frequency. The real-time resonant frequency is continuously acquired according to the preset sampling rate to obtain the timing resonant frequency.

[0010] The above scheme obtains the amplitude of the sinusoidal sweep frequency signal and the maximum frequency drift corresponding to the predicted acetylene concentration. Using the current resonant frequency as the center and this drift as the reference point, the sweep frequency range is determined. A real-time sinusoidal sweep voltage signal is generated and applied to the tuning fork. The output real-time piezoelectric current undergoes current-to-voltage conversion and phase-sensitive demodulation to obtain the real-time amplitude-frequency response curve. Lorentz fitting is performed on the real-time curve to obtain the real-time resonant frequency. The real-time resonant frequency is continuously acquired at a preset sampling rate to obtain the time-series resonant frequency. By adaptively adjusting the sweep frequency range and continuously fitting the real-time response data, time-series frequency data reflecting the dynamic adsorption process of acetylene is obtained, thus achieving real-time tracking of acetylene concentration changes while avoiding measurement delays caused by an excessively wide sweep frequency range.

[0011] As a preferred example, the step of modulating the driving laser according to the current resonant frequency and controlling the driving laser to irradiate the acetylene environment to be tested, in order to obtain the timing piezoelectric signal of the quartz tuning fork, includes: The wavelength is determined by taking half of the current resonant frequency as the modulation frequency and by determining the wavelength based on the characteristic absorption line of acetylene. The driving laser is modulated according to the wavelength and the modulation frequency, and the driving laser is controlled to pass through the gap between any two arms of the quartz tuning fork at a preset time interval to irradiate the acetylene environment to be tested. The optical real-time piezoelectric current signal output by the quartz tuning fork at each moment is obtained, and the optical real-time piezoelectric current signal is converted into an optical real-time piezoelectric voltage signal. Using the current resonant frequency as a reference frequency, the optical real-time piezoelectric voltage signal is demodulated with second harmonics to obtain the amplitude of the second harmonic signal; The amplitude of the second harmonic signal is continuously acquired according to the preset sampling rate to obtain the time-series piezoelectric signal.

[0012] The above scheme uses half of the current resonant frequency as the modulation frequency and determines the laser wavelength based on the acetylene characteristic absorption line. The driving laser is modulated according to this modulation frequency, controlling it to pass through the gap between the two arms of the tuning fork and illuminate the test environment. The real-time optical piezoelectric current output from the tuning fork is converted from current to voltage. Using the current resonant frequency as a reference, the voltage signal is demodulated using the second harmonic to obtain the second harmonic signal amplitude. This amplitude is continuously acquired at a preset sampling rate to obtain a time-series piezoelectric signal. By matching the laser modulation frequency with the tuning fork resonant frequency and demodulating the second harmonic of the piezoelectric signal, time-series amplitude data reflecting the acetylene photoacoustic absorption intensity is obtained, thus realizing the extraction of resonant-enhanced photoacoustic signals and effectively improving the signal-to-noise ratio of photoacoustic detection.

[0013] As a preferred example, the step of obtaining the first gas concentration of the acetylene environment to be tested based on the timing resonant frequency and the second gas concentration of the acetylene environment to be tested based on the timing piezoelectric signal includes: For any real-time resonant frequency in the time-series resonant frequencies, obtain the frequency drift between the real-time resonant frequency and the current resonant frequency. The first gas concentration corresponding to the real-time resonant frequency is obtained by multiplying the frequency drift by the pre-calibrated frequency concentration coefficient. For any second harmonic signal amplitude in the time-series piezoelectric signal, the second gas concentration corresponding to the second harmonic signal amplitude is obtained by multiplying the pre-calibrated amplitude concentration coefficient by the amplitude of the second harmonic signal.

[0014] The above scheme calculates the frequency drift of any real-time resonant frequency relative to the current resonant frequency, multiplies this drift by a pre-calibrated frequency concentration coefficient, and obtains the first gas concentration. Similarly, for any second harmonic signal amplitude in the time-series piezoelectric signal, it multiplies it by a pre-calibrated amplitude concentration coefficient to obtain the second gas concentration. By performing linear calibration on the frequency drift data and photoacoustic amplitude data respectively, concentration estimates under two physical mechanisms are obtained, thus realizing the conversion from different sensing links to a unified concentration dimension and providing directly comparable data pairs for subsequent fusion and judgment.

[0015] As a preferred example, obtaining the target gas concentration of the acetylene environment to be tested based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration includes: The first gas concentration and the second gas concentration corresponding to each sampling moment are obtained according to the preset sampling rate. For any given sampling time, obtain the absolute value of the concentration difference between the first gas concentration and the second gas concentration at that sampling time; When the absolute value of the concentration difference is less than or equal to a preset concentration difference threshold, the first gas concentration and the second gas concentration are weighted and summed to obtain the target gas concentration corresponding to the sampling time.

[0016] The above scheme acquires the first and second gas concentrations at each sampling time according to a preset sampling rate, and calculates the absolute value of the difference between the two as the concentration difference. When the concentration difference is less than or equal to a preset threshold, the first and second gas concentrations are weighted and summed to obtain the target gas concentration at that sampling time. By performing consistency judgment and weighted fusion processing on the dual-channel concentration estimates, a fused concentration that combines the advantages of both measurements is obtained. This reduces the impact of single-channel random errors on the final output when the dual-channel results are consistent, thus improving the accuracy and stability of concentration measurement.

[0017] As a preferred example, the step of obtaining the target gas concentration of the acetylene environment to be tested based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration further includes: When the absolute value of the concentration difference is greater than the preset concentration difference threshold, the frequency drift and the amplitude of the second harmonic signal are obtained at each sampling time. Obtain the drift difference between any two adjacent frequency drifts and the amplitude difference between any two adjacent second harmonic signal amplitudes; When any one of the drift difference values ​​is greater than or equal to a preset difference threshold and any one of the amplitude difference values ​​is less than the difference threshold, the second gas concentration at that sampling time is taken as the target gas concentration. When any one of the amplitude differences is greater than or equal to the difference threshold and any one of the drift differences is less than the difference threshold, the first gas concentration at that sampling time is taken as the target gas concentration.

[0018] The above scheme, when the absolute value of the concentration difference is greater than a preset threshold, acquires the frequency drift and second harmonic signal amplitude at each sampling moment, calculates the drift difference between two adjacent frequency drifts and the amplitude difference between two adjacent second harmonic amplitudes; when any drift difference is greater than or equal to a preset difference threshold and any amplitude difference is less than the threshold, the second gas concentration at that sampling moment is taken as the target gas concentration; when any amplitude difference is greater than or equal to a preset difference threshold and any drift difference is less than the threshold, the first gas concentration at that sampling moment is taken as the target gas concentration. By performing differential comparison processing on the temporal stability of the two channel signals, abnormal fluctuation channels are identified and the concentration output of the stable channel is automatically selected, thereby achieving reliable concentration acquisition under inconsistent operating conditions and avoiding erroneous measurements caused by instantaneous disturbances in a certain channel.

[0019] On the other hand, the present invention discloses a gas concentration detection system for acetylene, comprising a quartz tuning fork and a concentration detection device; wherein the quartz tuning fork comprises a vibrating arm and a composite sensitized film; wherein any two adjacent vibrating arms are arranged opposite each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitized film covers the side; the concentration detection device comprises an excitation module, a resonance module, a piezoelectric module, a concentration calculation module and a concentration detection module; The excitation module is electrically connected to the quartz tuning fork and is used to apply a sweep excitation to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork. The resonant module is electrically connected to the quartz tuning fork and is used to place the quartz tuning fork in the acetylene environment to be tested in order to obtain the timing resonant frequency of the quartz tuning fork. The piezoelectric module is electrically connected to the quartz tuning fork and is used to modulate the driving laser according to the current resonant frequency and control the driving laser to irradiate the acetylene environment under test in order to obtain the timing piezoelectric signal of the quartz tuning fork. The resonant module and the piezoelectric module are respectively signal-connected to the concentration calculation module, so that the concentration calculation module obtains the first gas concentration of the acetylene environment to be tested according to the time-series resonant frequency and the second gas concentration of the acetylene environment to be tested according to the time-series piezoelectric signal; The resonant module, the piezoelectric module, and the concentration calculation module are respectively signal-connected to the concentration detection module, so that the concentration detection module can obtain the target gas concentration of the acetylene environment to be tested based on the time-series resonant frequency, the first gas concentration, the time-series piezoelectric signal, and the second gas concentration.

[0020] This invention discloses a gas concentration detection system for acetylene. A frequency sweep excitation is applied to a quartz tuning fork coated with a composite sensitized film (the film is disposed on the inner surfaces of the two opposing arms). The output piezoelectric signal is demodulated and fitted to obtain the current resonant frequency reflecting the initial state of the tuning fork. The tuning fork is placed in the acetylene environment to be tested, and the frequency sweep response is continuously demodulated and fitted to obtain the time-series resonant frequency reflecting the dynamic adsorption process of acetylene. Based on the current resonant frequency, a driving laser is modulated to control the laser irradiation of the environment and perform second harmonic demodulation on the piezoelectric signal output by the tuning fork to obtain a time-series piezoelectric signal reflecting photoacoustic intensity. The time-series resonant frequency is frequency drift calculated and calibrated to obtain a first gas concentration. The time-series piezoelectric signal is then amplitude calibrated to obtain a second gas concentration. Finally, the time-series resonant frequency, the first gas concentration, the time-series piezoelectric signal, and the second gas concentration are subjected to consistency judgment and fusion processing to obtain the target gas concentration. The system disclosed in this invention achieves complementary detection through dual physical mechanisms by simultaneously acquiring and fusing two independent signals—electrical and photoacoustic—on the same composite sensitized quartz tuning fork. It utilizes both the efficient adsorption mass loading effect of the sensitized film on acetylene and the enhancement effect of the composite structure on photoacoustic relaxation, thereby improving the overall accuracy and environmental adaptability of acetylene concentration detection.

[0021] As a preferred example, the sidewall of the composite sensitized film facing the vibrating arm is attached to the side of the vibrating arm; the sidewall of the composite sensitized film facing away from the vibrating arm includes a first acetylene adsorption region and a second acetylene adsorption region; wherein, the first acetylene adsorption region is composed of a reduced graphene oxide film with a continuous sheet structure; and the second acetylene adsorption region is composed of sparse palladium nanoclusters.

[0022] The above scheme involves coating the sidewall of the vibrating arm with a composite sensitized film, while the other sidewall is configured with a first acetylene adsorption region and a second acetylene adsorption region. The first acetylene adsorption region is composed of a reduced graphene oxide film with a continuous sheet structure, and the second acetylene adsorption region is composed of sparse palladium nanoclusters. By designing a partitioned structure for the sensitized film, the reduced graphene oxide provides a high specific surface area adsorption interface and thermal conduction channels, while the palladium nanoclusters provide selective adsorption centers and energy relaxation pathways. This achieves efficient capture and rapid response of acetylene molecules, while simultaneously enhancing the mass loading effect and photoacoustic conversion efficiency, and improving the sensitivity of dual-mode detection.

[0023] As a preferred example, the excitation module includes a signal application unit and a signal acquisition unit; The input terminal of the signal application unit is electrically connected to the excitation pin of the quartz tuning fork, which is used to place the quartz tuning fork in a zero-air environment and apply a preset sinusoidal sweep voltage signal to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. The input terminal of the signal acquisition unit is electrically connected to the input terminal of the signal application unit, and is used to acquire the current piezoelectric current signal and convert the current piezoelectric current signal into a current piezoelectric voltage signal, and to perform phase-sensitive demodulation on the current piezoelectric voltage signal according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Lorentz fitting is performed on the amplitude-frequency response curve to obtain a fitting curve, and the center frequency of the fitting curve is used as the current resonant frequency of the quartz tuning fork.

[0024] In the above scheme, the signal application unit in the excitation module applies a sinusoidal sweep voltage to the tuning fork in a zero-gas environment. The signal acquisition unit acquires the piezoelectric current and converts it into a voltage. Based on the instantaneous frequency of the sweep voltage, the voltage signal undergoes phase-sensitive demodulation to obtain the amplitude-frequency response curve. Then, Lorentz fitting is performed on the curve to obtain the center frequency of the fitted curve as the current resonant frequency. By performing phase-sensitive demodulation and Lorentz fitting on the sweep response data, a precise reference frequency is obtained, thereby realizing the self-calibration function of the excitation module. This provides a stable and repeatable reference frequency for the entire detection system, ensuring the accuracy of subsequent mode switching and concentration calculation. Attached Figure Description

[0025] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of a gas concentration detection method for acetylene provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a quartz tuning fork provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a gas concentration detection device for acetylene provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a gas concentration detection system for acetylene provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0029] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0032] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0033] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0034] See Figure 1 To address the technical problem of accurately and rapidly detecting acetylene concentration in existing technologies, an embodiment of the present invention provides a method for detecting acetylene gas concentration, applied to a quartz tuning fork; the quartz tuning fork includes vibrating arms and a composite sensitized film; wherein any two adjacent vibrating arms are arranged opposite each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitized film covers the side to improve the accuracy of acetylene concentration detection; as shown below. Figure 1 As shown, the gas concentration detection method includes: Step 101: Apply a sweep excitation to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork.

[0035] Step 102: Place the quartz tuning fork in the acetylene environment to be tested to obtain the timing resonant frequency of the quartz tuning fork.

[0036] Step 103: Modulate the driving laser according to the current resonant frequency, and control the driving laser to irradiate the acetylene environment to be tested, so as to obtain the timing piezoelectric signal of the quartz tuning fork.

[0037] Step 104: Obtain the first gas concentration of the acetylene environment to be tested based on the time-series resonant frequency and the second gas concentration of the acetylene environment to be tested based on the time-series piezoelectric signal.

[0038] Step 105: Obtain the target gas concentration of the acetylene environment to be tested based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration.

[0039] The gas concentration detection method provided in this embodiment uses a composite sensitized quartz tuning fork as the core transducer for acetylene gas concentration detection. Specifically, the composite sensitized quartz tuning fork achieves the selection and switching between a purely electrical resonant frequency drift detection mode and a photoacoustic enhancement detection mode through a composite sensitization film coated on the vibrating arm, and further improves detection reliability through a joint criterion output.

[0040] Specifically, refer to Figure 2 This embodiment discloses a quartz tuning fork, mainly comprising a commercially available 32.768 kHz quartz tuning fork substrate consisting of a pair of resonant arms 21, a connecting base 20, and electrode pins 24. A composite sensitized film is attached to the inner surface of the two arms 21. The two arms 21 are parallel to each other and arranged opposite to each other, forming a narrow gap between them.

[0041] from Figure 2 It is known that a composite sensitizing film is attached to the inner surface of the two vibrating arms 21 (i.e., the surface where the two vibrating arms face each other). The inner wall of the composite sensitizing film directly covers the inner wall surface of the vibrating arms 21; its outer wall constitutes the working surface for adsorbing acetylene molecules. The composite sensitizing film includes a first base layer (i.e., the first adsorption region) 22 with a thickness of 50-200 nm, formed by reduced graphene oxide (rGO), which has a continuous wavy sheet structure to provide a high specific surface area acetylene adsorption interface and construct a good thermal conduction channel, while also serving as a carrier for Pd nanoclusters to ensure stable particle distribution; the nanoclusters (second adsorption region) 23 formed by Pd (rare palladium) have an average particle size of 2-10 nm and a surface coverage of less than 5%, serving as selective adsorption and catalytic centers for acetylene molecules, which can promote the rapid relaxation of molecular vibrational energy to thermal energy, thereby enhancing the local photoacoustic source term.

[0042] To ensure that the sensitized quartz tuning fork can simultaneously operate in both the purely electrical resonant frequency drift detection mode and the QEPAS photoacoustic enhancement detection mode, the total mass of the composite sensitized film was strictly controlled within the range of 0.1% to 1.0% of the effective mass of the inverted fundamental mode of the quartz tuning fork. Under this mass loading condition, the resonant frequency change rate Δf / f of the sensitized tuning fork was ≤1%, and the quality factor decreased by no more than 20%.

[0043] In this first embodiment, the composite sensitized film is prepared according to the following steps: (1) Open the quartz tuning fork housing, clean the surface of the vibrating arm 21 with isopropanol and dry it; optionally, perform... Plasma treatment is used to improve surface adhesion.

[0044] (2) Take 0.1 to 0.5 μL of rGO dispersion with a concentration of 0.5 mg / mL and drop it onto the upper middle section of the inner side of the two vibrating arms 21. After natural drying, dry it at a low temperature of 50 to 60 °C for 10 to 20 minutes to form a continuous rGO thin layer (i.e., the first acetylene adsorption zone).

[0045] (3) Micro-droplets of 0.05–0.5 mM MgO are added to the formed rGO film. The solution was prepared, and an equal volume of 1 mM solution was added. The solution was subjected to an in-situ reduction reaction to generate sparse Pd nanoclusters (i.e., the second acetylene adsorption region). The solution was then rinsed with ethanol and dried to complete the preparation of the composite sensitized film.

[0046] (4) Measure the resonant frequency and quality factor before and after sensitization to confirm that the quality control requirements of Δf / f≤1% and ΔQ / Q≤20% are met.

[0047] The rGO-Pd composite sensitized quartz tuning fork prepared in the above manner can not only enhance the adsorption mass loading effect of acetylene molecules, but also significantly promote the relaxation process of acetylene vibrational energy in photoacoustic detection, thus possessing the dual functions of frequency drift detection and photoacoustic enhancement detection.

[0048] In this embodiment, step 101 includes: Step 1011: Place the quartz tuning fork in a zero-air environment and apply a preset sinusoidal sweep voltage signal to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. Step 1012: Convert the current piezoelectric current signal into a current piezoelectric voltage signal, and perform phase-sensitive demodulation on the current piezoelectric voltage signal according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Step 1013: Perform Lorentz fitting on the amplitude-frequency response curve to obtain the fitted curve and use the center frequency of the fitted curve as the current resonant frequency of the quartz tuning fork.

[0049] This embodiment provides an acetylene gas detection device for controlling a quartz tuning fork to detect acetylene gas concentration. The acetylene gas detection device selectively includes an electrical excitation link. This electrical excitation link includes a function generator and a drive amplifier, used to apply sweep frequency excitation or lock frequency excitation to the composite sensitized quartz tuning fork in a purely electrical mode.

[0050] Will as Figure 2The composite sensitized quartz tuning fork shown is placed in a zero-gas environment (e.g., pure nitrogen or clean air, with a known zero acetylene concentration). A preset sinusoidal sweep voltage signal is output from a function generator; this signal is a low-amplitude sine wave whose frequency varies linearly with time. This sweep signal is amplified by a driver amplifier and then applied to the excitation pin of the quartz tuning fork. Under this sweep excitation, the quartz tuning fork generates mechanical vibration and outputs a piezoelectric current signal proportional to the vibration amplitude, denoted as the current piezoelectric current signal.

[0051] The obtained current piezoelectric current signal is fed into a transimpedance amplifier and converted into a current piezoelectric voltage signal. This voltage signal is then input to the signal input terminal of a lock-in amplifier. Simultaneously, the synchronization output of the function generator (i.e., the reference signal of the current sweep frequency) is connected to the reference input terminal of the lock-in amplifier.

[0052] The lock-in amplifier uses the instantaneous sweep frequency of the sinusoidal swept voltage signal as the demodulation frequency to perform phase-sensitive demodulation on the current piezoelectric voltage signal. After demodulation, it outputs two components: an in-phase component X and a quadrature component Y, from which the amplitude corresponding to each swept frequency point can be calculated. The computer synchronously records each swept frequency point and its corresponding amplitude, thus obtaining the amplitude-frequency response curve. This amplitude-frequency response curve reflects the amplitude distribution of the tuning fork under different frequency excitations.

[0053] The obtained amplitude-frequency response curve was subjected to Lorentz analysis, and the center frequency of the fitted curve was taken as the current resonant frequency of the quartz tuning fork under the current environment (zero gas). Simultaneously, the quality factor was calculated based on the fitting results. The obtained current resonant frequency and quality factor were recorded as the system's current resonant state parameters and stored in the computer. These parameters are used for concentration inversion in the subsequent pure electrical resonant frequency drift detection mode and for setting the laser modulation frequency in the photoacoustic enhanced detection mode.

[0054] When the device is in pure electrical resonant frequency drift detection mode, the resonant frequency and quality factor of the current quartz tuning fork are obtained through the aforementioned frequency sweep measurement (or alternatively, frequency locking measurement), and this parameter is recorded as the current resonant state of the system. The computer equipment is configured to perform resonant parameter recording and initialization calibration during detection mode switching, thereby ensuring that an accurate reference frequency can be obtained in different modes.

[0055] The above implementation applies a sinusoidal sweep voltage signal to a quartz tuning fork placed in a zero-gas environment. The acquired piezoelectric current signal is then converted from current to voltage. Phase-sensitive demodulation is performed on the voltage signal based on the instantaneous frequency of the sweep voltage to obtain an amplitude-frequency response curve reflecting the frequency-amplitude relationship. This curve is then Lorentz-fitted to obtain the center frequency of the fitted curve as the current resonant frequency. By performing phase-sensitive demodulation and Lorentz-fitting on the sweep response data, a precise reference frequency is obtained, thus achieving high-precision self-calibration of the tuning fork's resonant frequency under acetylene interference-free conditions, providing a stable reference zero point for subsequent frequency drift measurements.

[0056] In this embodiment, step 102 includes: Step 1021: Obtain the signal amplitude of the sinusoidal sweep voltage signal and the predicted acetylene concentration of the acetylene environment to be tested, so as to query the maximum frequency drift corresponding to the predicted acetylene concentration. Step 1022: Using the current resonant frequency as the frequency center, determine the sweep frequency range based on the frequency center and the maximum frequency drift. Step 1023: Generate a real-time sinusoidal sweep frequency voltage signal based on the signal amplitude and the sweep frequency range, and apply the real-time sinusoidal sweep frequency voltage signal to the excitation pin to obtain the real-time piezoelectric current signal output by the quartz tuning fork; Step 1024: Convert the real-time piezoelectric current signal into a real-time piezoelectric voltage signal, and perform phase-sensitive demodulation on the real-time piezoelectric voltage signal according to the instantaneous sweep frequency of the real-time sinusoidal sweep voltage signal to obtain a real-time amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Step 1025: Perform Lorentz fitting on the real-time amplitude-frequency response curve to obtain the real-time fitting curve and take the center frequency of the real-time fitting curve as the real-time resonant frequency. Step 1026: Continuously acquire the real-time resonant frequency according to the preset sampling rate to obtain the timing resonant frequency.

[0057] In this embodiment, when the device operates in the pure electrical resonant frequency drift detection mode, the current resonant frequency and quality factor of the quartz tuning fork are first obtained in a zero-air environment according to the method described above, and recorded as the current resonant state of the system. This reference frequency is used for subsequent calculation of the frequency drift.

[0058] The amplitude of the sinusoidal sweep voltage signal used in the zero-gas environment is obtained (this amplitude is a preset low value to ensure the tuning fork operates in the linear region). Simultaneously, based on the expected concentration range of the acetylene environment to be tested (e.g., the predicted acetylene concentration obtained through historical data or field experience), a pre-calibrated concentration-frequency drift table is consulted to obtain the maximum frequency drift corresponding to the predicted concentration. This query process can be based on linear interpolation or a preset formula.

[0059] The current resonant frequency is used as the frequency center, and the maximum frequency drift is used to determine the sweep frequency range. Specifically, the sweep frequency range is [current resonant frequency − k times the maximum frequency drift, current resonant frequency + k times the maximum frequency drift], where k is a safety factor greater than 1 (usually taken as 1.2 to 1.5) to ensure that the sweep frequency range can cover the frequency drift that may actually occur.

[0060] Based on the acquired signal amplitude and the determined sweep frequency range, a function generator produces a real-time sinusoidal sweep voltage signal. The amplitude of this signal is the same as that used in a zero-air environment, and its frequency linearly changes from the starting frequency (current resonant frequency - k times the maximum frequency drift) to the ending frequency (current resonant frequency + k times the maximum frequency drift). The sweep rate can be set according to the measurement speed requirements (e.g., 10–50 Hz / s). This real-time sinusoidal sweep voltage signal is applied to the excitation pin of the quartz tuning fork via a drive amplifier. Under the sweep excitation, the tuning fork generates mechanical vibration and outputs a piezoelectric current signal proportional to the vibration amplitude, denoted as the real-time electrical piezoelectric current signal.

[0061] The obtained real-time piezoelectric current signal is fed into a transimpedance amplifier and converted into a real-time piezoelectric voltage signal. This voltage signal is then input to the signal input terminal of a lock-in amplifier (LPA), while the synchronous output of the function generator (i.e., the instantaneous sweep frequency of the real-time sinusoidal sweep voltage signal) is connected to the reference input terminal of the LPA. The LPA uses this instantaneous sweep frequency as the demodulation frequency to perform phase-sensitive demodulation on the real-time piezoelectric voltage signal, outputting the amplitude corresponding to each sweep frequency point. The computer synchronously records each sweep frequency point and its corresponding amplitude to obtain the real-time amplitude-frequency response curve.

[0062] The obtained real-time amplitude-frequency response curve is subjected to Lorentz fitting. The form of the fitting function is the same as that used to obtain the current resonant frequency: the center frequency of the fitted curve is obtained through least squares fitting, and this center frequency is taken as the real-time resonant frequency at the current moment.

[0063] By repeating the above steps at a preset sampling rate (e.g., 10 Hz, i.e., 10 frequency points per second), a series of real-time resonant frequency values ​​are continuously obtained, thus yielding the time-series resonant frequency. This time-series data reflects the change of the tuning fork resonant frequency over time, and its decrease is proportional to the acetylene adsorption mass.

[0064] The above implementation method obtains the amplitude of the sinusoidal sweep frequency signal and the maximum frequency drift corresponding to the predicted acetylene concentration. Using the current resonant frequency as the center and this drift as the reference value, a sweep frequency range is determined. A real-time sinusoidal sweep voltage signal is generated and applied to the tuning fork. The output real-time piezoelectric current undergoes current-to-voltage conversion and phase-sensitive demodulation to obtain the real-time amplitude-frequency response curve. Lorentz fitting is performed on the real-time curve to obtain the real-time resonant frequency. The real-time resonant frequency is continuously acquired at a preset sampling rate to obtain the time-series resonant frequency. By adaptively adjusting the sweep frequency range and continuously fitting the real-time response data, time-series frequency data reflecting the dynamic adsorption process of acetylene is obtained, thereby achieving real-time tracking of acetylene concentration changes while avoiding measurement delays caused by an excessively wide sweep frequency range.

[0065] In this embodiment, step 103 includes: Step 1031: Use half of the current resonant frequency as the modulation frequency of the wavelength and determine the wavelength based on the characteristic absorption line of acetylene. Step 1032: Modulate the driving laser according to the wavelength and the modulation frequency, and control the driving laser to pass through the gap between any two arms of the quartz tuning fork at a preset time interval to irradiate the acetylene environment to be tested; Step 1033: Obtain the optical real-time piezoelectric current signal output by the quartz tuning fork at each moment, and convert the optical real-time piezoelectric current signal into an optical real-time piezoelectric voltage signal; Step 1034: Using the current resonant frequency as a reference frequency, perform second harmonic demodulation on the optical real-time piezoelectric voltage signal to obtain the amplitude of the second harmonic signal; Step 1035: Continuously acquire the amplitude of the second harmonic signal according to the preset sampling rate to obtain the time-series piezoelectric signal.

[0066] The acetylene gas detection device in this embodiment selectively includes an optical excitation link. This optical excitation link includes a laser, a laser driver, a modulation adder, and a fiber optic collimating lens, used to provide modulated laser light to the gas to be tested in optical detection mode to excite a photoacoustic effect. When the device switches from electrical detection mode to photoacoustic enhancement detection mode, the current resonant frequency obtained in the previous steps is used to set the laser modulation frequency and the demodulation reference frequency of the lock-in amplifier.

[0067] Specifically, half of the obtained current resonant frequency is used as the modulation frequency, and the center wavelength of the driving laser is determined based on the characteristic absorption spectral lines of the acetylene molecule. This wavelength should be located near the characteristic absorption line of acetylene to ensure effective absorption of laser energy by the acetylene molecule.

[0068] Based on the determined wavelength and modulation frequency, a driving laser is generated. Specifically, a function generator outputs a low-frequency sawtooth wave and a high-frequency sinusoidal modulation signal, which are superimposed by a modulation adder and then input to the laser driver, causing the laser to output a modulated laser with a wavelength that periodically changes near the acetylene characteristic absorption line. This modulated laser is shaped into a parallel beam by an optical fiber collimating lens and passes through the gap between any two arms of a quartz tuning fork at preset time intervals (i.e., continuous irradiation or pulse train form) to irradiate the acetylene environment to be tested. The preset time interval can be set according to the detection requirements; for example, continuous irradiation in continuous monitoring mode and irradiation once at fixed intervals in intermittent detection mode.

[0069] Under modulated laser irradiation, acetylene molecules in the acetylene environment absorb laser energy and convert vibrational energy into heat energy through a relaxation process, generating periodic local thermal expansion and forming photoacoustic waves. These photoacoustic waves drive the quartz tuning fork to produce mechanical resonance near its resonant frequency in the gap region between the tuning fork arms. Due to the piezoelectric effect, the quartz tuning fork converts the mechanical vibration into a current signal, which is the optical real-time piezoelectric current signal. This current signal is acquired and converted into an optical real-time piezoelectric voltage signal by a transimpedance amplifier.

[0070] Using the current resonant frequency as the reference frequency of the lock-in amplifier, the obtained real-time optical piezoelectric voltage signal is demodulated using its second harmonic. Specifically, the lock-in amplifier performs phase-sensitive detection between the input signal and the second harmonic of the reference frequency, extracting the amplitude of the second harmonic signal that is proportional to the acetylene concentration.

[0071] By repeating the above steps at a preset sampling rate (e.g., 10 Hz, i.e., 10 amplitude points per second), a series of second harmonic signal amplitudes are continuously obtained, thus yielding a time-series piezoelectric signal. This time-series data reflects the change in photoacoustic signal intensity over time and is positively correlated with acetylene concentration.

[0072] The above implementation uses half of the current resonant frequency as the modulation frequency and determines the laser wavelength based on the acetylene characteristic absorption line. The driving laser is modulated according to this modulation frequency, controlling the laser to pass through the gap between the two arms of the tuning fork and irradiate the test environment. The real-time optical piezoelectric current output from the tuning fork is converted from current to voltage. The voltage signal is then demodulated using the second harmonic with the current resonant frequency as a reference to obtain the second harmonic signal amplitude. This amplitude is continuously acquired at a preset sampling rate to obtain a time-series piezoelectric signal. By matching the laser modulation frequency with the tuning fork resonant frequency and demodulating the second harmonic of the piezoelectric signal, time-series amplitude data reflecting the acetylene photoacoustic absorption intensity is obtained, thereby realizing the extraction of resonant-enhanced photoacoustic signals and effectively improving the signal-to-noise ratio of photoacoustic detection.

[0073] In this embodiment, step 104 includes: Step 1041: For any real-time resonant frequency in the time-series resonant frequencies, obtain the frequency drift between the real-time resonant frequency and the current resonant frequency; Step 1042: Obtain the first gas concentration corresponding to the real-time resonant frequency by multiplying the frequency drift by the pre-calibrated frequency concentration coefficient. Step 1043: For any second harmonic signal amplitude in the time-series piezoelectric signal, obtain the second gas concentration corresponding to the second harmonic signal amplitude by multiplying the pre-calibrated amplitude concentration coefficient by the second harmonic signal amplitude.

[0074] In this embodiment, any real-time resonant frequency among the obtained timing resonant frequencies is considered. and the current resonant frequency obtained in Example 2 Calculate the frequency shift; due to the adsorption of acetylene molecules leading to an increase in the equivalent mass of the tuning fork, the resonant frequency decreases. >0; based on the pre-calibrated frequency-concentration conversion coefficient (Unit: Hz / ppm), convert the frequency drift to the first gas concentration: ; Theoretical basis: Under small mass perturbation conditions (the total mass of the composite sensitization layer is controlled within the range of 0.1% to 1.0% of the effective mass of the tuning fork, and the additional mass caused by acetylene adsorption is much smaller than this value), the resonant frequency drift of the quartz tuning fork satisfies an approximately linear relationship with the equivalent additional mass.

[0075] The modal displacement of the tuning fork's out-of-phase fundamental mode is expressed as: ,in For normalized mode functions, If we use generalized coordinates, then the kinetic energy of this mode is: Among them, effective quality The calculation formula is: The r represents the spatial coordinates, r = (x, y, z); Accordingly, the elastic potential energy of this mode is: The Let x be the material density distribution, x be the displacement function, referring to the actual displacement of the tuning fork, and dV be a volume element used to perform volume integrals over the entire tuning fork; It represents the equivalent stiffness.

[0076] Among them, the effective mass and the equivalent stiffness are respectively , From the single-degree-of-freedom equivalent oscillator model, its undamped free vibration equation is: Therefore, the angular frequency of the inverted fundamental mode of the quartz tuning fork satisfies ; Therefore, the natural frequency of the tuning fork satisfies: .

[0077] When acetylene molecules adsorb onto the surface of the rGO-Pd sensitized layer, it causes an equivalent mass perturbation. In this application, the total mass of the sensitized layer and the additional mass caused by acetylene adsorption are much smaller than the effective mass of the tuning fork's antiphase fundamental mode, and the additional mass is mainly distributed in the sensitive region of the vibrating arm. Therefore, it can be equivalent to a first-order perturbation of the effective modal mass, while the equivalent stiffness remains approximately unchanged under small adsorption conditions. The perturbed intrinsic frequency can then be written as: Rearrange the above equation as follows: because According to binomial Expand: Substitution Taking a first-order approximation, we get: Therefore, the frequency drift is Wherein, e represents the effective mass change rate; This is the equivalent added mass caused by gas adsorption on the surface of the rGO-Pd composite sensitized layer, which is mainly composed of the adsorption mass of acetylene molecules. This is composed of the baseline mass perturbation of the sensitized layer. It can be seen that, under small mass perturbation conditions, the resonant frequency drift of the quartz tuning fork satisfies an approximately linear relationship with the equivalent added mass, and the larger the added mass, the lower the resonant frequency. This relationship constitutes the theoretical basis for concentration inversion in the purely electrical resonant frequency drift detection mode.

[0078] Because the present invention will If the error is limited to the range of 0.1% to 1.0%, then the magnitude of the second-order error term is... Much smaller than the first-order term Therefore, the linear mapping between frequency drift and adsorbed mass is fully engineering-reasonable. Furthermore, the adsorbed mass can be decomposed into a sensitization layer constant and an acetylene adsorption variable: in, This is a fixed mass loading term introduced into the sensitized layer after preparation. This is the mass term representing the variable caused by acetylene adsorption. The measurement is performed at the reference frequency during device initialization. eliminate A constant offset, thus subsequent frequency drift is mainly due to The decision was made to achieve acetylene concentration output, i.e. Based on the above resonant frequency drift The calculation formula thus enables quantitative calibration of the relationship between acetylene concentration and resonant frequency drift. As shown in the previous derivation, under conditions of small mass perturbation, the resonant frequency drift of the quartz tuning fork satisfies an approximately linear relationship with the added mass: And the adsorption mass of acetylene Within a certain concentration range, it approximately satisfies a linear adsorption relationship with the gas concentration C: in Let be the proportionality coefficient between the adsorbed mass and the gas concentration. Substituting this into the above equation, we get: Therefore, the electrical detection channel can establish a concentration estimation relationship: in This is the frequency drift-concentration conversion coefficient obtained after calibration.

[0079] For any second harmonic signal amplitude in the obtained time-series piezoelectric signal According to the pre-calibrated amplitude-concentration conversion coefficient (Unit: ppm / V or dimensionless), calculate the concentration of the second gas: Theoretical basis: In photoacoustic enhanced detection mode, the laser outputs a modulated laser with a center wavelength near the characteristic absorption line of acetylene. Because the acetylene molecules absorb the incident light, the absorption power varies periodically with time. Let the incident laser power be... The effective absorption coefficient of acetylene at the corresponding absorption line is: Under low absorption conditions, the power absorbed by the gas per unit time can be approximately expressed as: Where m is the modulation depth. The modulation angular frequency. The periodic component of the absorbed power constitutes the energy source for photoacoustic excitation; the... This represents the effective absorption coefficient of acetylene at the corresponding absorption line.

[0080] The light energy absorbed by acetylene molecules is not instantly converted into heat energy. Instead, it undergoes a relaxation process from the vibrational energy levels to the translational and rotational degrees of freedom, ultimately forming a localized periodic heat source. Let the effective relaxation time of the system be... Then the response of the periodic heat source to the modulation excitation can be equivalently represented as a first-order relaxor system, whose heat source amplitude satisfies Alternatively, it can be written in the form that it is proportional to the power of the heat source. in, This is a proportionality coefficient related to the local thermoacoustic conversion efficiency of the gas pool. As can be seen from the above equation, when the effective relaxation time... When the vibrational energy absorbed by the molecules is large, it is difficult to convert it into a heat source that changes synchronously with the modulation in a timely manner, resulting in a weakening of photoacoustic excitation; conversely, when... When shortened, the heat source term increases, and the photoacoustic signal is enhanced; the aforementioned The amplitude (or intensity) representing the periodic heat source (photoacoustic excitation source); It represents the effective relaxation time, which is the characteristic time required for an acetylene molecule to convert vibrational energy into thermal energy after absorbing light energy.

[0081] In this embodiment, the composite sensitized film not only serves as the acetylene adsorption interface but also provides an additional relaxation channel for the dissipation of acetylene vibrational energy. Specifically, the Pd nanoclusters provide an electronic coupling dissipation path, and the rGO film provides a phonon diffusion and heat conduction path. Therefore, the effective relaxation process of the system can be represented as the result of multiple parallel mechanisms working together, i.e. in, Let be the intrinsic collision relaxation time of acetylene molecules in the background atmosphere. The equivalent time constant for electronic coupling dissipation introduced by Pd nanoclusters. Let Pd be the equivalent time constant for phonon diffusion and interfacial heat dissipation provided by the rGO sheets. Since the parallel relaxation mechanism satisfies the reciprocal addition relationship, after introducing Pd and rGO, The time constant is smaller than that during simple gas-phase relaxation, thereby increasing the amplitude of the periodic heat source.

[0082] The sound wave source is formed by localized thermal expansion and pressure fluctuations generated by a periodic heat source. This sound wave source drives the tuning fork to vibrate in the gap region between the arms of the quartz tuning fork. Since the quartz tuning fork can be equivalent to a second-order resonator with a high quality factor, it vibrates at an angular frequency... The displacement response of a point to an acoustic driving force can be written as: in, The equivalent driving force is sound pressure. The equivalent stiffness of the tuning fork's inverse fundamental mode. ω is the inverted fundamental mode resonant angular frequency of the tuning fork, and Q is the quality factor.

[0083] When the modulation conditions satisfy the QEPAS resonance enhancement condition, i.e., the frequency corresponding to the second harmonic component matches the resonant frequency of the tuning fork, then... At this point, the above equation reaches its maximum value near resonance, and the amplitude of the tuning fork response approximately satisfies... Among them, the This represents the amplitude of the vibration displacement of the quartz tuning fork under resonant conditions (resonance response amplitude). Since the piezoelectric output current of the quartz tuning fork is proportional to its mechanical vibration amplitude, the amplitude of the second harmonic photoacoustic signal obtained after transimpedance amplification and lock-in amplification is... It can be represented as Substituting further into the heat source expression, we can obtain Fixed parameters related to device structure, amplifier gain, beam position, and cell constant are incorporated into the overall coefficient. Then it can be written as As can be seen from the above equation, the output signal in QEPAS mode is related to the acetylene absorption coefficient. Incident laser power The modulation depth m and the quality factor Q of the quartz tuning fork are positively correlated, while the effective relaxation time is positively correlated. Negative correlation. Therefore, this invention introduces additional relaxation channels through the rGO-Pd composite sensitization layer, which can effectively reduce... This improves heat source conversion efficiency and enhances QEPAS output amplitude while maintaining a high quality factor for the tuning fork.

[0084] In actual testing, to match the second harmonic component with the resonant frequency of the quartz tuning fork, the present invention preferably sets the laser modulation frequency. satisfy in, This is the resonant frequency of the current quartz tuning fork. Correspondingly, the lock-in amplifier uses the second harmonic reference frequency. Phase-sensitive demodulation is performed to enable the QEPAS channel to operate under optimal resonant gain conditions and obtain the maximum signal-to-noise ratio output.

[0085] In actual testing, when the laser power Modulation depth m, tuning fork quality factor Q, and relaxation time When the signal remains stable for a short period of time, the amplitude of the photoacoustic signal and the acetylene absorption coefficient The amplitude of the photoacoustic signal, i.e., the amplitude of the second harmonic signal, is directly proportional to the concentration of the gas C, and the absorption coefficient is also directly proportional to the concentration of the gas C. Therefore, the amplitude of the photoacoustic signal, i.e., the amplitude of the second harmonic signal, can be written as: This allows for the estimation of the concentration in the photoacoustic detection channel: Or it can be written in a uniform form: in The concentration conversion coefficient of the photoacoustic signal obtained through system calibration.

[0086] In the joint criterion detection mode, the device simultaneously acquires measurement signals from the electrical detection channel and the photoacoustic detection channel within the same time window, obtaining two independent concentration estimates. These two concentration estimates originate from different physical mechanisms (mass adsorption and photoacoustic relaxation), and their error sources are unrelated, providing a basis for subsequent consistency judgment and fusion. The frequency-concentration conversion coefficient and amplitude-concentration conversion coefficient can be obtained through pre-calibration using acetylene standard gas of known concentration and stored in the computer equipment.

[0087] In the above implementation method, for any real-time resonant frequency in the time-series resonant frequencies, the frequency drift between the real-time resonant frequency and the current resonant frequency is calculated. This drift is then multiplied by a pre-calibrated frequency concentration coefficient to obtain the first gas concentration. For any second harmonic signal amplitude in the time-series piezoelectric signal, it is multiplied by a pre-calibrated amplitude concentration coefficient to obtain the second gas concentration. By performing linear calibration processing on the frequency drift data and photoacoustic amplitude data respectively, concentration estimates under two physical mechanisms are obtained, thereby realizing the conversion from different sensing links to a unified concentration dimension, providing directly comparable data pairs for subsequent fusion judgment.

[0088] In this embodiment, step 105 includes: Step 1051: Obtain the first gas concentration and the second gas concentration corresponding to each sampling time according to the preset sampling rate; Step 1052: For any of the sampling times, obtain the absolute value of the concentration difference between the first gas concentration and the second gas concentration at that sampling time; Step 1053: When the absolute value of the concentration difference is less than or equal to a preset concentration difference threshold, the first gas concentration and the second gas concentration are weighted and summed to obtain the target gas concentration corresponding to the sampling time.

[0089] Step 1054: When the absolute value of the concentration difference is greater than the preset concentration difference threshold, obtain the frequency drift and the amplitude of the second harmonic signal at each sampling time. Step 1055: Obtain the drift difference between any two adjacent frequency drifts and the amplitude difference between any two adjacent second harmonic signal amplitudes; Step 1056: When any one of the drift difference values ​​is greater than or equal to a preset difference threshold and any one of the amplitude difference values ​​is less than the difference threshold, the second gas concentration at the sampling time is taken as the target gas concentration; Step 1057: When any one of the amplitude differences is greater than or equal to the difference threshold and any one of the drift differences is less than the difference threshold, the first gas concentration at the sampling time is taken as the target gas concentration.

[0090] In this embodiment, the first gas concentration corresponding to each sampling time is obtained according to a preset sampling rate. Second gas concentration .in Frequency drift inversion results from the electrical detection channel, Amplitude inversion results from the photoacoustic detection channel.

[0091] For any sampling time t, calculate the absolute value of the difference between the concentration of the first gas and the concentration of the second gas at that time: .

[0092] when (in When the concentration difference threshold (i.e., the consistency bandwidth) is reached, the results of the two channels are determined to be consistent, and the fused concentration is output. Wherein, the weight coefficients satisfy The weighting coefficients can be dynamically determined based on the noise variance or signal-to-noise ratio of the two channel signals, for example: in and These represent the standard deviations of the measurement noise for the two detection channels. This weighting method automatically assigns lower weights to channels with higher noise levels, thereby improving the stability of the fusion concentration.

[0093] when When an inconsistency event occurs, it is determined to be an inconsistency event. At this time, the frequency drift sequence and the second harmonic signal amplitude sequence within the time window of the sampling time are obtained; for the above sequences, the changes between any two adjacent sampling times are calculated: the difference in frequency drift and the difference in second harmonic amplitude.

[0094] When any drift difference is greater than or equal to a preset difference threshold (i.e., the frequency drift shows a significant step change) and all amplitude differences are less than the difference threshold (i.e., the second harmonic amplitude is stable), it indicates that the output of the electrical channel is constantly changing and unstable. Therefore, the second gas concentration (i.e., the photoacoustic channel concentration) at this sampling moment is taken as the target gas concentration. When any amplitude difference is greater than or equal to a preset difference threshold (i.e., the second harmonic amplitude shows a significant step change) and all drift differences are less than the difference threshold (i.e., the frequency drift is stable), it indicates that the output of the optical channel is constantly changing and unstable. Therefore, the first gas concentration (i.e., the electrical channel concentration) at this sampling moment is taken as the target gas concentration.

[0095] Other inconsistencies: If both channels show significant changes but the trend of change does not conform to the calibration consistency (e.g., one increases while the other decreases), or if neither channel responds but the concentration difference still exceeds the threshold, an alarm will be output indicating the presence of mixed interference, and the complete self-calibration process will be triggered.

[0096] When an inconsistency event occurs, the device may not directly output the concentration, but instead trigger targeted operations based on the directionality of the inconsistency: If the optical channel is determined to be abnormal, an optical link self-test is triggered (checking laser power, wavelength lock status, optical path alignment, etc.) or the resonant point calibration is re-executed and retested.

[0097] If an electrical channel malfunction is detected, a baseline update is triggered (the reference frequency under zero pressure is remeasured). Alternatively, extend the averaging time and retest.

[0098] If both channels are abnormal but do not conform to any of the above single modes, an alarm will be output, indicating the presence of mixed interference, and manual inspection is recommended.

[0099] Since the electrical detection channel is mainly affected by interfacial adsorption and mass loading, while the photoacoustic detection channel is mainly affected by absorption-relaxation-thermoacoustic conversion and optical coupling, the physical mechanisms of their errors are different and weakly correlated. The joint criterion mode requires both channels to be identical before outputting the fusion concentration, ensuring that the false positive probability meets the following condition: in, This indicates the probability that the frequency drift detection channel will generate a false alarm under acetylene-free conditions. This indicates the probability of a false alarm generated by the photoacoustic detection channel. Because... and Since all values ​​are less than 1, the false alarm probability under the joint criterion is significantly lower than that of any single channel, thereby significantly improving the reliability of acetylene detection in complex environments and forming an engineering-featured self-diagnosis and self-calibration capability.

[0100] The above implementation method acquires the first gas concentration and the second gas concentration at each sampling time according to a preset sampling rate, and calculates the absolute value of the difference between the two as the concentration difference. When the concentration difference is less than or equal to a preset threshold, the first gas concentration and the second gas concentration are weighted and summed to obtain the target gas concentration at that sampling time. By performing consistency judgment and weighted fusion processing on the dual-channel concentration estimates, a fused concentration that combines the advantages of the two measurements is obtained, thereby reducing the impact of single-channel random error on the final output when the dual-channel results are consistent, and improving the accuracy and stability of concentration measurement. When the absolute value of the concentration difference is greater than the preset threshold, the frequency drift and the amplitude of the second harmonic signal at each sampling time are acquired, and the drift difference between two adjacent frequency drifts and the amplitude difference between two adjacent second harmonic amplitudes are calculated. When any drift difference is greater than or equal to a preset difference threshold and any amplitude difference is less than the threshold, the second gas concentration at that sampling time is taken as the target gas concentration; when any amplitude difference is greater than or equal to a preset difference threshold and any drift difference is less than the threshold, the first gas concentration at that sampling time is taken as the target gas concentration. By performing differential comparison processing on the timing stability of the two channels, abnormal fluctuation channels are identified and the concentration output of the stable channel is automatically selected, thereby achieving reliable concentration acquisition under inconsistent operating conditions and avoiding erroneous measurements caused by instantaneous disturbances in a certain channel.

[0101] Based on the above method embodiments, corresponding device embodiments are provided; one embodiment of the present invention provides a gas concentration detection system for acetylene, including a quartz tuning fork and a concentration detection device; wherein, the quartz tuning fork includes a vibrating arm and a composite sensitizing film; wherein, any two adjacent vibrating arms are arranged opposite to each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitizing film covers the side; the concentration detection device is as follows Figure 3 As shown, it includes an excitation module 301, a resonance module 302, a piezoelectric module 303, a concentration calculation module 304, and a concentration detection module 305.

[0102] The excitation module 301 is electrically connected to the quartz tuning fork and is used to apply a sweep frequency excitation to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork.

[0103] The resonant module 302 is electrically connected to the quartz tuning fork and is used to place the quartz tuning fork in the acetylene environment to be tested in order to obtain the timing resonant frequency of the quartz tuning fork. The piezoelectric module 303 is electrically connected to the quartz tuning fork and is used to modulate the driving laser according to the current resonant frequency and control the driving laser to irradiate the acetylene environment to be tested, so as to obtain the timing piezoelectric signal of the quartz tuning fork. The resonant module 302 and the piezoelectric module 303 are respectively signal-connected to the concentration calculation module 304, so that the concentration calculation module 304 obtains the first gas concentration of the acetylene environment to be tested according to the time-series resonant frequency and obtains the second gas concentration of the acetylene environment to be tested according to the time-series piezoelectric signal; The resonant module 302, the piezoelectric module 303, and the concentration calculation module 304 are respectively connected to the concentration detection module 305 so that the concentration detection module 305 can obtain the target gas concentration of the acetylene environment to be tested based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration.

[0104] In this embodiment one implementation, refer to Figure 4 This embodiment provides a gas concentration detection system for acetylene, which mainly includes a vibration generator 1, a composite sensitized quartz tuning fork 2, a signal demodulation device 3, a laser 4, a function generator 5, a laser modulation drive link including an adder 6 and a laser driver 7, an optical fiber collimating lens 8, and a computer device 9.

[0105] like Figure 4 As shown, the electrode pins of the composite sensitized quartz tuning fork 2 are electrically connected to the input terminal of the signal demodulation device 3 and the reference output terminal of the laser modulation drive link, respectively. The laser 4 outputs continuous laser light with a center wavelength near the characteristic absorption line of acetylene. The drive input terminal of the laser 4 is connected to the output terminal of the laser modulation drive link. Its outgoing light path, after being collimated by the fiber collimating lens 8, passes through the gap between the two arms 21 of the quartz tuning fork 2 and irradiates the acetylene environment to be tested. The laser modulation drive link includes a function generator 5 and an adder 6. The function generator 5 outputs two signals: one is a low-frequency sawtooth wave scanning signal, used to achieve slow scanning of the laser wavelength; the other is a high-frequency sinusoidal modulation signal, the frequency of which is set by the computer device 9 according to the current resonant frequency. The two signals are superimposed by the adder 6 used for signal modulation and then sent to the drive current input terminal of the laser 4, thereby performing composite modulation of the output wavelength of the laser 4 using high-frequency modulation and low-frequency scanning.

[0106] The signal demodulation device 3 includes a preamplifier 31 and a lock-in amplifier 32. The input terminal of the preamplifier 31 is connected to the electrode pin 24 of the quartz tuning fork 2, and is used to convert the weak piezoelectric current signal output by the tuning fork into a voltage signal. The signal input terminal of the lock-in amplifier 32 is connected to the output terminal of the transimpedance amplifier, and its reference input terminal is connected to the synchronization output of the function generator 5 (or the reference frequency provided by the computer device 9). The lock-in amplifier 32 uses the current resonant frequency as the reference frequency to perform second harmonic demodulation on the input signal, and extracts the second harmonic signal amplitude that is proportional to the acetylene concentration.

[0107] Computer device 9 is connected to the control terminals of function generator 5, lock-in amplifier 32, and laser 4, respectively. Computer device 9 performs the following functions: receiving second harmonic amplitude data from lock-in amplifier to form a timing piezoelectric signal; calculating and setting the laser modulation frequency and lock-in amplifier reference frequency based on the current resonant frequency; storing and processing detection data; and outputting acetylene concentration information.

[0108] The signal interaction process is as follows: Computer device 9 reads the pre-stored current resonant frequency and sends the modulation frequency parameters to function generator 5, which then generates a sinusoidal modulation signal.

[0109] The sinusoidal modulation signal of function generator 5 and the low-frequency sawtooth wave scanning signal generated internally are superimposed by adder 6 to drive laser 4 to output a modulated laser with a wavelength that changes periodically near the acetylene characteristic absorption line.

[0110] The modulated laser passes through the gap between the arms of the quartz tuning fork 2 and irradiates the acetylene gas to be tested. After absorbing the laser energy, the acetylene molecules generate periodic photoacoustic waves through a relaxation process.

[0111] The photoacoustic wave drives the quartz tuning fork 2 to generate mechanical resonance near its resonant frequency. The tuning fork 2 uses the piezoelectric effect to convert the mechanical vibration into a piezoelectric current signal.

[0112] The piezoelectric current signal is converted into a voltage signal by the transimpedance amplifier and then sent to the signal input terminal of the lock-in amplifier; at the same time, the reference input terminal of the lock-in amplifier receives the synchronization reference signal of the function generator 5.

[0113] The lock-in amplifier uses the current resonant frequency as a reference frequency to perform second harmonic demodulation and outputs the second harmonic signal amplitude to the computer device 9.

[0114] Computer device 9 continuously collects the second harmonic amplitude at a preset sampling rate to form a time-series piezoelectric signal, and calculates the acetylene concentration based on the pre-stored calibration coefficient.

[0115] Through the above-mentioned module composition and signal interaction. Figure 4 The device shown realizes acetylene concentration measurement in photoacoustic enhanced detection mode, and adaptively sets laser modulation parameters using the current resonant frequency to ensure that photoacoustic demodulation always works at the optimal resonant gain point.

[0116] In this embodiment, the sidewall of the composite sensitized film facing the vibrating arm is attached to the side of the vibrating arm; the sidewall of the composite sensitized film facing away from the vibrating arm includes a first acetylene adsorption region and a second acetylene adsorption region; wherein, the first acetylene adsorption region is composed of a reduced graphene oxide film with a continuous sheet structure; and the second acetylene adsorption region is composed of sparse palladium nanoclusters.

[0117] In this embodiment, the excitation module 401 includes a signal application unit and a signal acquisition unit; The input terminal of the signal application unit is electrically connected to the excitation pin of the quartz tuning fork, which is used to place the quartz tuning fork in a zero-air environment and apply a preset sinusoidal sweep voltage signal to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. The input terminal of the signal acquisition unit is electrically connected to the input terminal of the signal application unit, and is used to acquire the current piezoelectric current signal and convert the current piezoelectric current signal into a current piezoelectric voltage signal, and to perform phase-sensitive demodulation on the current piezoelectric voltage signal according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Lorentz fitting is performed on the amplitude-frequency response curve to obtain a fitting curve, and the center frequency of the fitting curve is used as the current resonant frequency of the quartz tuning fork.

[0118] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the gas concentration detection method for acetylene provided by any of the above-described method embodiments of the present invention.

[0119] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0120] Based on the above embodiment of a method for detecting acetylene gas concentration, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a method for detecting acetylene gas concentration according to any embodiment of the present invention.

[0121] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0122] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0123] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0124] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute a gas concentration detection method for acetylene as described in any of the above-described method embodiments of the present invention.

[0125] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0126] This embodiment discloses a method and system for detecting acetylene gas concentration. Using the same rGO-Pd composite sensitized quartz tuning fork as the sole gas transducer, it establishes three selectable operating states based on the same signal readout link: one is a purely electrical frequency drift detection state, used for outputting signals in scenarios without optical conditions or low-power continuous monitoring. It quickly provides a concentration estimate and simultaneously provides the device with a real-time resonant point. The first is the Q-value measurement, used for self-calibration of the subsequent photoacoustic demodulation reference; the second is the QEPAS photoacoustic enhancement detection state, used for output in high-sensitivity detection scenarios. And obtain high signal-to-noise ratio concentration information; thirdly, joint criterion detection state, in which the device synchronously obtains and Furthermore, a redundant verification mechanism is constructed through consistency constraints and fusion outputs, ensuring that the detection results are not only "measurable" but also "verifiable," thereby significantly reducing false alarms and missed alarms in complex atmospheres or disturbed environments. Because It mainly reflects the mass loading of the interface adsorption, while This primarily reflects the absorption-relaxation-thermoacoustic conversion efficiency. Since the two are affected by different perturbation mechanisms, the joint criterion can convert drift and interference, which are difficult to distinguish with a single channel, into identifiable "inconsistency events," triggering retesting or calibration. This allows the present invention to simultaneously achieve high sensitivity and high reliability in room-temperature acetylene detection. The present invention measures the tuning fork resonant frequency in real time using an electrical detection mode and uses it for photoacoustic mode demodulation reference updates, thus forming an adaptive resonance tracking detection mechanism.

[0127] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for detecting acetylene gas concentration, characterized in that, The method is applied to a quartz tuning fork; the quartz tuning fork includes a vibrating arm and a composite sensitized film; wherein any two adjacent vibrating arms are arranged opposite each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitized film covers the side; the gas concentration detection method includes: A frequency sweep excitation is applied to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork; The quartz tuning fork is placed in the acetylene environment to be tested in order to obtain the timing resonant frequency of the quartz tuning fork. The driving laser is modulated according to the current resonant frequency, and the driving laser is controlled to irradiate the acetylene environment to be tested, so as to obtain the timing piezoelectric signal of the quartz tuning fork; The first gas concentration of the acetylene environment to be tested is obtained according to the time-series resonant frequency, and the second gas concentration of the acetylene environment to be tested is obtained according to the time-series piezoelectric signal. The target gas concentration of the acetylene environment to be tested is obtained based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration.

2. The method for detecting acetylene gas concentration according to claim 1, characterized in that, Applying a frequency sweep excitation to the quartz tuning fork to obtain its current resonant frequency includes: The quartz tuning fork is placed in a zero-air environment, and a preset sinusoidal sweep voltage signal is applied to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. The current piezoelectric current signal is converted into a current piezoelectric voltage signal, and the current piezoelectric voltage signal is phase-sensitively demodulated according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; The amplitude-frequency response curve is subjected to Lorentz fitting to obtain the fitted curve, and the center frequency of the fitted curve is taken as the current resonant frequency of the quartz tuning fork.

3. The method for detecting acetylene gas concentration according to claim 2, characterized in that, The step of placing the quartz tuning fork in the acetylene environment to be tested to obtain the timing resonant frequency of the quartz tuning fork includes: The signal amplitude of the sinusoidal sweep voltage signal and the predicted acetylene concentration of the acetylene environment to be tested are obtained, so as to find out the maximum frequency drift corresponding to the predicted acetylene concentration. The current resonant frequency is used as the frequency center, and the sweep frequency range is determined based on the frequency center and the maximum frequency drift. A real-time sinusoidal sweep voltage signal is generated based on the signal amplitude and the sweep frequency range, and the real-time sinusoidal sweep voltage signal is applied to the excitation pin to obtain the real-time piezoelectric current signal output by the quartz tuning fork. The real-time piezoelectric current signal is converted into a real-time piezoelectric voltage signal, and the real-time piezoelectric voltage signal is demodulated in a phase-sensitive manner according to the instantaneous sweep frequency of the real-time sinusoidal sweep voltage signal to obtain a real-time amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Lorentz fitting is performed on the real-time amplitude-frequency response curve to obtain the real-time fitted curve, and the center frequency of the real-time fitted curve is taken as the real-time resonant frequency. The real-time resonant frequency is continuously acquired according to the preset sampling rate to obtain the timing resonant frequency.

4. The method for detecting acetylene gas concentration according to claim 2, characterized in that, The step of modulating the driving laser according to the current resonant frequency and controlling the driving laser to irradiate the acetylene environment under test to obtain the timing piezoelectric signal of the quartz tuning fork includes: The wavelength is determined by taking half of the current resonant frequency as the modulation frequency and by determining the wavelength based on the characteristic absorption line of acetylene. The driving laser is modulated according to the wavelength and the modulation frequency, and the driving laser is controlled to pass through the gap between any two arms of the quartz tuning fork at a preset time interval to irradiate the acetylene environment to be tested. The optical real-time piezoelectric current signal output by the quartz tuning fork at each moment is obtained, and the optical real-time piezoelectric current signal is converted into an optical real-time piezoelectric voltage signal. Using the current resonant frequency as a reference frequency, the optical real-time piezoelectric voltage signal is demodulated with second harmonics to obtain the amplitude of the second harmonic signal; The amplitude of the second harmonic signal is continuously acquired according to the preset sampling rate to obtain the time-series piezoelectric signal.

5. A method for detecting acetylene gas concentration according to any one of claims 1-4, characterized in that, The step of obtaining the first gas concentration of the acetylene environment to be tested based on the time-series resonant frequency and obtaining the second gas concentration of the acetylene environment to be tested based on the time-series piezoelectric signal includes: For any real-time resonant frequency in the time-series resonant frequencies, obtain the frequency drift between the real-time resonant frequency and the current resonant frequency. The first gas concentration corresponding to the real-time resonant frequency is obtained by multiplying the frequency drift by the pre-calibrated frequency concentration coefficient. For any second harmonic signal amplitude in the time-series piezoelectric signal, the second gas concentration corresponding to the second harmonic signal amplitude is obtained by multiplying the pre-calibrated amplitude concentration coefficient by the amplitude of the second harmonic signal.

6. The method for detecting acetylene gas concentration according to claim 5, characterized in that, The step of obtaining the target gas concentration of the acetylene environment to be tested based on the timing resonant frequency, the first gas concentration, the timing piezoelectric signal, and the second gas concentration includes: The first gas concentration and the second gas concentration corresponding to each sampling moment are obtained according to the preset sampling rate. For any given sampling time, obtain the absolute value of the concentration difference between the first gas concentration and the second gas concentration at that sampling time; When the absolute value of the concentration difference is less than or equal to a preset concentration difference threshold, the first gas concentration and the second gas concentration are weighted and summed to obtain the target gas concentration corresponding to the sampling time.

7. The method for detecting acetylene gas concentration according to claim 6, characterized in that, The step of obtaining the target gas concentration of the acetylene environment to be tested based on the time-series resonant frequency, the first gas concentration, the time-series piezoelectric signal, and the second gas concentration further includes: When the absolute value of the concentration difference is greater than the preset concentration difference threshold, the frequency drift and the amplitude of the second harmonic signal are obtained at each sampling time. Obtain the drift difference between any two adjacent frequency drifts and the amplitude difference between any two adjacent second harmonic signal amplitudes; When any one of the drift difference values ​​is greater than or equal to a preset difference threshold and any one of the amplitude difference values ​​is less than the difference threshold, the second gas concentration at that sampling time is taken as the target gas concentration. When any one of the amplitude differences is greater than or equal to the difference threshold and any one of the drift differences is less than the difference threshold, the first gas concentration at that sampling time is taken as the target gas concentration.

8. A gas concentration detection system for acetylene, characterized in that, The device includes a quartz tuning fork and a concentration detection device; the quartz tuning fork includes a vibrating arm and a composite sensitized film; wherein any two adjacent vibrating arms are arranged opposite each other and each vibrating arm has a side facing its adjacent vibrating arm; the composite sensitized film covers the side; the concentration detection device includes an excitation module, a resonance module, a piezoelectric module, a concentration calculation module and a concentration detection module; The excitation module is electrically connected to the quartz tuning fork and is used to apply a sweep excitation to the quartz tuning fork to obtain the current resonant frequency of the quartz tuning fork. The resonant module is electrically connected to the quartz tuning fork and is used to place the quartz tuning fork in the acetylene environment to be tested in order to obtain the timing resonant frequency of the quartz tuning fork. The piezoelectric module is electrically connected to the quartz tuning fork and is used to modulate the driving laser according to the current resonant frequency and control the driving laser to irradiate the acetylene environment under test in order to obtain the timing piezoelectric signal of the quartz tuning fork. The resonant module and the piezoelectric module are respectively signal-connected to the concentration calculation module, so that the concentration calculation module obtains the first gas concentration of the acetylene environment to be tested according to the time-series resonant frequency and the second gas concentration of the acetylene environment to be tested according to the time-series piezoelectric signal; The resonant module, the piezoelectric module, and the concentration calculation module are respectively signal-connected to the concentration detection module, so that the concentration detection module can obtain the target gas concentration of the acetylene environment to be tested based on the time-series resonant frequency, the first gas concentration, the time-series piezoelectric signal, and the second gas concentration.

9. A gas concentration detection system for acetylene according to claim 8, characterized in that, The composite sensitized film is attached to the sidewall of the vibrating arm facing the sidewall of the vibrating arm; the sidewall of the composite sensitized film facing away from the vibrating arm includes a first acetylene adsorption region and a second acetylene adsorption region; wherein, the first acetylene adsorption region is composed of a reduced graphene oxide film with a continuous sheet structure; and the second acetylene adsorption region is composed of sparse palladium nanoclusters.

10. A gas concentration detection system for acetylene according to claim 8, characterized in that, The excitation module includes a signal application unit and a signal acquisition unit; The input terminal of the signal application unit is electrically connected to the excitation pin of the quartz tuning fork, which is used to place the quartz tuning fork in a zero-air environment and apply a preset sinusoidal sweep voltage signal to the excitation pin of the quartz tuning fork to obtain the current piezoelectric current signal output by the quartz tuning fork. The input terminal of the signal acquisition unit is electrically connected to the input terminal of the signal application unit, and is used to acquire the current piezoelectric current signal and convert the current piezoelectric current signal into a current piezoelectric voltage signal, and to perform phase-sensitive demodulation on the current piezoelectric voltage signal according to the instantaneous sweep frequency of the sinusoidal sweep voltage signal to obtain an amplitude-frequency response curve; wherein, the amplitude-frequency response curve includes the amplitude corresponding to each sweep frequency point; Lorentz fitting is performed on the amplitude-frequency response curve to obtain a fitting curve, and the center frequency of the fitting curve is used as the current resonant frequency of the quartz tuning fork.

Images