Coupled photoacoustic multi-gas sensor based on double balls

Abstract

The invention discloses a double-ball coupling type photoacoustic multi-gas sensor, which comprises a shell, a double-ball coupling type photoacoustic cell is arranged in the shell, the double-ball coupling type photoacoustic cell comprises a large ball body and a small ball body which are coupled with each other, the maximum sound pressure is located in the whole small ball body, and the maximum sound pressure is located in the whole small ball body. The tail end of the small sphere is provided with a cantilever beam sonic sensor used for detecting a photoacoustic signal, and the cantilever beam sonic sensor is internally provided with a cantilever beam which is in positive correlation with the concentration of gas in the photoacoustic cell. The double-ball coupling type photoacoustic cell is composed of two mutually-coupled balls, the low-concentration gas detection capacity is remarkably improved, multi-gas detection can be achieved, and due to the fact that the vibration amplitude of the cantilever beam is in positive correlation with the gas concentration in the photoacoustic cell, the gas concentration in the photoacoustic cell can be accurately detected by accurately detecting the vibration amplitude of the cantilever beam. The gas concentration change in the photoacoustic cell can be effectively reflected, and the photoacoustic cell has the advantages of low detection limit, high Q value, strong stability, high sensitivity, good signal-to-noise ratio, low cost and the like.

Description

Technical Field

[0001] The invention relates to the technical field of gas detection, and in particular to a double-ball coupling type photoacoustic multi-gas sensor. Background Art

[0002] Trace gas detection plays an extremely important role in air quality monitoring, disease prevention and treatment, and certain safety precautions. This detection can not only effectively monitor harmful gases in the environment and ensure people's health, but also play a key role in industrial production and environmental protection.

[0003] With the continuous advancement of laser technology, photoacoustic spectroscopy has gradually become a trace gas detection technology that has attracted much attention. This method has been widely recognized and adopted in research and applications at home and abroad due to its high sensitivity, high selectivity, wide dynamic range and real-time data analysis capabilities.

[0004] Photoacoustic spectroscopy is a measurement method based on indirect absorption spectroscopy. Its core principle is to use the gas photoacoustic effect to cleverly convert the absorbed light energy into acoustic pressure wave signals. Specifically, when gas molecules absorb light energy of a specific wavelength, their energy state changes, transitioning from the ground state to the excited state. Since the excited state is relatively unstable, the gas molecules will quickly return to the ground state and release heat in the process. The released heat causes the surrounding gas to expand, resulting in pressure changes. When the incident light is periodically modulated, the gas in the photoacoustic pool will experience periodic expansion and contraction. Such changes cause the acoustic pressure wave signals in the gas to be continuously generated, and this pressure wave has obvious periodic characteristics. Through highly sensitive photoacoustic detectors, researchers can accurately capture these pressure wave signals and invert the gas concentration information by analyzing the characteristics of these signals. This method can not only achieve effective detection of low-concentration gases, but also obtain accurate measurement results in a short time.

[0005] However, it is difficult to achieve simultaneous detection of three or more gases using traditional photoacoustic spectroscopy technology. In summary, designing a photoacoustic gas sensor that can simultaneously detect multiple gases with high sensitivity has important application value. Summary of the invention

[0006] The technical problem to be solved by the present invention is: how to provide a photoacoustic gas sensor capable of simultaneously detecting multiple gases with high sensitivity.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] The invention is based on a double-ball coupled photoacoustic multi-gas sensor, comprising a shell, wherein a double-ball coupled photoacoustic cell is arranged inside the shell, wherein the double-ball coupled photoacoustic cell comprises a large sphere and a small sphere coupled to each other, wherein the maximum sound pressure is located inside the entire small sphere, and a cantilever beam acoustic wave sensor for detecting photoacoustic signals is installed at the end of the small sphere, wherein a cantilever beam positively correlated with the gas concentration inside the photoacoustic cell is installed inside the cantilever beam acoustic wave sensor.

[0009] The present application sets up a double-ball coupled photoacoustic cell, which is the core part of the sensor. Its structure consists of two mutually coupled spheres, which significantly improves the detection capability of low-concentration gas and can realize multi-gas detection. Since the vibration amplitude of the cantilever beam is positively correlated with the gas concentration inside the photoacoustic cell, the gas concentration change inside the photoacoustic cell can be effectively reflected by accurately detecting the vibration amplitude of the cantilever beam. This double-ball coupled photoacoustic sensor not only has the advantages of low detection limit, high Q value, strong stability, high sensitivity, good signal-to-noise ratio and low cost, but also provides a new idea for the detection of lower-sensitivity gases.

[0010] As a further solution of the present invention: a rectangular pit is provided on the cantilever beam acoustic wave sensor, a cantilever beam is formed on the floor of the rectangular pit, and the cantilever beam is located at the top of one side of the small sphere.

[0011] As a further solution of the present invention: one end of the shell away from the cantilever beam acoustic wave sensor is connected to a collimator by gluing.

[0012] As a further solution of the present invention: the cantilever beam is a silicon dioxide slice processed by MEMS technology.

[0013] As a further solution of the present invention: one side of the cantilever beam is fixed, and the other three sides can vibrate freely.

[0014] As a further solution of the present invention: an air inlet and an air outlet connected to the double-ball coupled photoacoustic cell are provided at both ends of the shell.

[0015] As a further solution of the present invention: when the ratio between the radius of the large sphere and the radius of the small sphere satisfies 8:1, the photoacoustic signal is maximum.

[0016] As a further solution of the present invention: the radius of the large sphere is 24 mm, and the radius of the small sphere is 3 mm.

[0017] As a further solution of the present invention: the coupling distance between the large sphere and the small sphere is 0.2-0.5 mm.

[0018] As a further solution of the present invention: the double-ball coupled photoacoustic cell has five resonance frequencies below 10000 Hz, which is used for simultaneous detection of five gases.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present application sets up a double-ball coupled photoacoustic cell, which is the core part of the sensor. Its structure consists of two mutually coupled spheres, which significantly improves the detection capability of low-concentration gases and can realize multi-gas detection. Since the vibration amplitude of the cantilever beam is positively correlated with the gas concentration inside the photoacoustic cell, the change of gas concentration inside the photoacoustic cell can be effectively reflected by accurately detecting the vibration amplitude of the cantilever beam. This double-ball coupled photoacoustic sensor not only has the advantages of low detection limit, high Q value, strong stability, high sensitivity, good signal-to-noise ratio and low cost, but also provides a new idea for the detection of gases with lower sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a double-ball coupling type photoacoustic multi-gas sensor according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a cantilever beam acoustic wave sensor according to an embodiment of the present invention;

[0023] Figure 3 This is a COMSOL simulation diagram of a double-sphere coupled photoacoustic cell according to an embodiment of the present invention;

[0024] Description of reference numerals:

[0025] 1. Collimator; 2. Shell; 3. Air inlet; 4. Double-ball coupled photoacoustic cell; 5. Air outlet; 6. Cantilever beam acoustic wave sensor; 7. Cantilever beam; 8. Silicon dioxide wafer. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Reference Figure 1 and Figure 2 , based on a double-ball coupled photoacoustic multi-gas sensor, includes a collimator 1, a shell 2, an air inlet 3, a double-ball coupled photoacoustic cell 4, an air outlet 5, a cantilever beam acoustic wave sensor 6, a cantilever beam 7 and a silicon dioxide wafer 8.

[0028] Reference Figure 1 and Figure 2 The collimator 1 is fixedly connected to one side of the shell 2 by gluing, which is used for accurate calibration of the excitation light source. The excitation light source transmits the excitation light to the photoacoustic cavity of the double-ball coupled photoacoustic cell 4 through the collimator 1, and generates a photoacoustic effect with the gas to generate a photoacoustic signal.

[0029] Reference Figure 1 and Figure 2 The shell 2 is a 3D printed shell, and an air inlet 3 and an air outlet 5 connected to a double-ball coupled photoacoustic cell 4 are provided at both ends of the shell 2, wherein the air inlet 3 and the air outlet 5 are used for gas input and gas discharge, respectively, to ensure smooth gas exchange.

[0030] Reference Figure 1 and Figure 2 A double-ball coupled photoacoustic cell 4 is arranged in the 3D printed shell, and the double-ball coupled photoacoustic cell 4 is used to generate and amplify photoacoustic signals. The double-ball coupled photoacoustic cell 4 includes a large sphere and a small sphere. The two mutually coupled spheres form a special photoacoustic cavity, and the maximum sound pressure is located in the entire small sphere.

[0031] Further, when the radius of the large sphere is 24 mm, the radius of the small sphere is 3 mm, and the ratio of the radius between the large sphere and the small sphere satisfies 8:1, the photoacoustic signal is the largest. The setting of the radius between the large sphere and the small sphere here can be determined according to actual conditions, and this application does not limit it, and only gives one preferred implementation mode;

[0032] Furthermore, the coupling distance between the large sphere and the small sphere is 0.2mm-0.5mm. The coupling distance between the large sphere and the small sphere can be determined according to actual conditions. This application does not limit it, and only provides one preferred range.

[0033] Reference Figure 1 and Figure 2 The cantilever beam acoustic wave sensor 6 is placed at the end of the small sphere in the double-sphere coupled photoacoustic pool 4, and a rectangular pit is opened on the cantilever beam acoustic wave sensor 6; the three sides of the bottom surface of the rectangular pit are gaps to form a cantilever beam 7, which is placed at the top of one side of the small sphere to measure the maximum value of the acoustic wave energy, thereby achieving detection of lower gas concentrations.

[0034] Furthermore, the cantilever beam 7 used in the structure is a silicon dioxide sheet 8 processed by MEMS technology, which is made by laser processing technology on a silicon dioxide sheet using MEMS technology. One side of the cantilever beam 7 is fixed, and the other three sides can vibrate freely (such as Figure 2 As shown), the sound signal can be detected by combining with the FP interference demodulation method.

[0035] The double-ball coupled photoacoustic cell 4 of the present application has five resonance frequencies below 10000 Hz, namely 4520 Hz, 6990 Hz, 7800 Hz, 9820 Hz, and 9990 Hz, and can be used for the simultaneous detection of five environmental pollutant gases, namely CO2, CO, CH4, C2H2, and H2S.

[0036] Figure 3 is a COMSOL simulation diagram of a double-ball coupled photoacoustic cell 4, where Figure 3 The horizontal axis represents the frequency, and the vertical axis represents the size of the photoacoustic signal. From the simulation results in the figure, it can be seen that there are five peaks, which are used to measure five gases. That is, at the resonant frequencies of 4520Hz, 6990Hz, 7800Hz, 9820Hz, and 9990Hz, the corresponding photoacoustic signal sizes can be measured.

[0037] The specific operating principles of this application are as follows:

[0038] The collimator 1 is fixedly connected to the 3D printed shell 2 by gluing, which is used for accurate calibration of the excitation light source; the double-ball coupled photoacoustic pool 4 is used to generate and amplify the photoacoustic signal; the air inlet 3 and the air outlet 5 of the 3D printed shell 2 are used for gas input and discharge, respectively, to ensure smooth gas exchange; the cantilever beam acoustic wave sensor 6 is placed at the end of the small sphere in the double-ball coupled photoacoustic pool 4, which is used to detect the maximum photoacoustic signal. The excitation light source transmits the excitation light into the photoacoustic cavity through the collimator 1, and the photoacoustic effect occurs with the gas to generate a photoacoustic signal. The signal is amplified in the small sphere of the double-ball coupled photoacoustic pool 4, and the cantilever beam acoustic wave sensor 6 receives and collects the signal, and finally transmits the signal to the computer for processing, thereby obtaining the concentration information of the gas to be measured.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Based on double-ball coupling type photoacoustic multi-gas sensor, characterized in that: The invention comprises a shell (2), wherein a double-ball coupled photoacoustic cell (4) is arranged inside the shell (2), wherein the double-ball coupled photoacoustic cell (4) comprises a large sphere and a small sphere coupled to each other, wherein the maximum sound pressure is located inside the entire small sphere, and a cantilever beam acoustic wave sensor (6) for detecting photoacoustic signals is installed at the end of the small sphere, wherein a cantilever beam acoustic wave sensor (6) is installed inside the cantilever beam acoustic wave sensor (6) and is positively correlated with the gas concentration inside the photoacoustic cell.

2. The double-ball coupling photoacoustic multi-gas sensor according to claim 1 is characterized in that: The cantilever beam acoustic wave sensor (6) is provided with a rectangular pit, the floor of the rectangular pit forms a cantilever beam (7), and the cantilever beam (7) is located at the top end of one side of the small sphere.

3. The double-sphere coupled photoacoustic multi-gas sensor according to claim 1, characterized in that: One end of the housing (2) away from the cantilever beam acoustic wave sensor (6) is connected to the collimator (1) by gluing.

4. The double-ball coupling photoacoustic multi-gas sensor according to claim 1, characterized in that: The cantilever beam (7) is a silicon dioxide thin sheet (8) processed using MEMS technology.

5. The double-sphere coupled photoacoustic multi-gas sensor according to claim 4 is characterized in that: One side of the cantilever beam (7) is fixed, and the other three sides are able to vibrate freely.

6. The double-ball coupling photoacoustic multi-gas sensor according to claim 1, characterized in that: An air inlet (3) and an air outlet (5) connected to a double-ball coupling photoacoustic cell (4) are provided at both ends of the shell (2).

7. The double-ball coupling photoacoustic multi-gas sensor according to claim 1, characterized in that: When the ratio between the radius of the large sphere and the radius of the small sphere meets 8:1, the photoacoustic signal is maximum.

8. The double-ball coupling type photoacoustic multi-gas sensor according to claim 7, characterized in that: The radius of the large sphere is 24 mm, and the radius of the small sphere is 3 mm.

9. The double-sphere coupling photoacoustic multi-gas sensor according to claim 1, characterized in that: The distance between the large sphere and the small sphere coupled to each other is 0.2-0.5 mm.

10. The double-ball coupling photoacoustic multi-gas sensor according to claim 1, characterized in that: The double-ball coupling type photoacoustic cell (4) has five resonance frequencies below 10000 Hz and is used for detecting five gases simultaneously.

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