Dual-ball coupled photoacoustic multi-gas sensor

Abstract

The application discloses a double-ball coupling type photoacoustic multi-gas sensor based on a shell, the inside of the shell is provided with a double-ball coupling type photoacoustic cell, the double-ball coupling type photoacoustic cell comprises a big ball and a small ball which are coupled with each other, the maximum sound pressure is located in the whole small ball, a cantilever beam sound wave sensor for detecting a photoacoustic signal is installed at the end of the small ball, and the cantilever beam sound wave sensor is internally provided with a cantilever beam which is positively correlated with the gas concentration in the photoacoustic cell. The double-ball coupling type photoacoustic cell is composed of two coupled balls, the detection capability for low-concentration gas is significantly improved, multi-gas detection can be realized, the vibration amplitude of the cantilever beam is positively correlated with the gas concentration in the photoacoustic cell, the vibration amplitude of the cantilever beam is accurately detected, the gas concentration change in the photoacoustic cell can be effectively reflected, and the application has the advantages of low detection limit, high Q value, strong stability, high sensitivity, good signal-to-noise ratio and low cost.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of gas detection, in particular to a dual-ball coupling type photoacoustic multi-gas sensor. BACKGROUND

[0002] Trace gas detection plays an extremely important role in air quality monitoring, disease prevention and treatment, and some safety prevention fields. Such detection can not only effectively monitor harmful gases in the environment to ensure the health of people, but also plays a key role in industrial production and environmental protection.

[0003] With the continuous progress 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 application 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 photoacoustic effect of gas to cleverly convert the absorbed light energy into an acoustic pressure wave signal. Specifically, when gas molecules absorb light energy of a specific wavelength, their energy state changes from the ground state to the excited state. Since the excited state is relatively unstable, the gas molecules quickly return to the ground state and release heat in the process. The released heat causes the surrounding gas to expand, resulting in a change in pressure. When the incident light is periodically modulated, the gas in the photoacoustic cell undergoes periodic expansion and contraction. Such changes cause the acoustic pressure wave signal in the gas to continuously generate, and this pressure wave has obvious periodic characteristics. Through a high-sensitivity photoacoustic detector, researchers can accurately capture these pressure wave signals and analyze their characteristics to retrieve the concentration information of the gas. This method not only enables effective detection of low-concentration gases, but also allows accurate measurement results to be obtained in a short time.

[0005] However, traditional photoacoustic spectroscopy technology is difficult to achieve simultaneous detection of three or more gases. Therefore, it is of great application value to design a photoacoustic gas sensor that can simultaneously and highly sensitively detect multiple gases. SUMMARY

[0006] The technical problem to be solved by the application is to provide a photoacoustic gas sensor that can simultaneously and highly sensitively detect multiple gases.

[0007] To solve the above technical problems, the application provides the following technical solutions.

[0008] The application discloses a double-ball coupling type photoacoustic multi-gas sensor, which comprises a shell, and a double-ball coupling type photoacoustic cell is arranged in the shell.

[0009] The double-ball coupling type photoacoustic cell is a core part of the sensor, which is composed of two mutually coupled balls, and the detection capability of low-concentration gas is improved, and multi-gas detection can be realized.

[0010] As a further scheme of the application, a rectangular pit is formed on the cantilever beam acoustic wave sensor, and a cantilever beam is formed on the bottom surface of the rectangular pit.

[0011] As a further scheme of the application, a collimator is connected to one end of the shell away from the cantilever beam acoustic wave sensor by means of adhesion.

[0012] As a further scheme of the application, the cantilever beam is a silicon dioxide sheet processed by MEMS technology.

[0013] As a further scheme of the application, one side of the cantilever beam is fixed, and the other three sides can freely vibrate.

[0014] As a further scheme of the application, gas inlet holes and gas outlet holes are formed in both ends of the shell and communicate with the double-ball coupling type photoacoustic cell.

[0015] As a further scheme of the application, when the ratio between the radius of the large ball and the radius of the small ball is 8:1, the photoacoustic signal is maximum.

[0016] As a further scheme of the application, the radius of the large ball is 24 mm, and the radius of the small ball is 3 mm.

[0017] As a further scheme of the application, the distance between the large ball and the small ball is 0.2-0.5 mm.

[0018] As a further scheme of the present application: the double-ball coupling type photoacoustic cell has five resonance frequencies below 10000Hz, for simultaneous detection of five kinds of gas.

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

[0020] The present application sets a double-ball coupling type photoacoustic cell, which is the core part of the sensor, and is composed of two mutually coupled spheres, significantly improving the detection capability of low-concentration gas, and enabling multi-gas detection. Since the vibration amplitude of the cantilever beam is positively correlated with the gas concentration inside the photoacoustic cell, accurate detection of the vibration amplitude of the cantilever beam can effectively reflect the change in the gas concentration inside the photoacoustic cell. This double-ball coupling type 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 gas. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The present application is based on the structure of a double-ball coupling type photoacoustic multi-gas sensor.

[0022] Figure 2 The present application is based on the structure of a cantilever beam acoustic sensor.

[0023] Figure 3 The present application is based on the COMSOL simulation of a double-ball coupling type photoacoustic cell.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] 1, collimator; 2, shell; 3, gas inlet hole; 4, double-ball coupling type photoacoustic cell; 5, gas outlet hole; 6, cantilever beam acoustic sensor; 7, cantilever beam; 8, silicon dioxide sheet. DETAILED DESCRIPTION

[0026] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described below in detail. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0027] Referring to Figure 1 and Figure 2 , the double-ball coupling type photoacoustic multi-gas sensor includes a collimator 1, a shell 2, a gas inlet hole 3, a double-ball coupling type photoacoustic cell 4, a gas outlet hole 5, a cantilever beam acoustic sensor 6, a cantilever beam 7 and a silicon dioxide sheet 8.

[0028] Referring to Figure 1 and Figure 2 , the collimator 1 is fixedly connected to one side of the shell 2 by means of adhesion, for precise calibration of the excitation light source, which transmits excitation light into the photoacoustic cavity of the double-ball coupling type photoacoustic cell 4 through the collimator 1, and generates photoacoustic signals by photoacoustic effect with the gas.

[0029] Referring to Figure 1 and Figure 2 , the shell 2 is a 3D printed shell, and the shell 2 is provided with a gas inlet hole 3 and a gas outlet hole 5 at two ends for communicating with the double-ball coupling type photoacoustic cell 4, wherein the gas inlet hole 3 and the gas outlet hole 5 are respectively used for gas input and discharge, to ensure smooth gas exchange.

[0030] Referring to Figure 1 and Figure 2 , the double-ball coupling type photoacoustic cell 4 is arranged in the 3D printed shell, and is used for generating and amplifying photoacoustic signals. The double-ball coupling type photoacoustic cell 4 contains a large ball and a small ball, and the two mutually coupled balls form a special photoacoustic cavity, and the maximum sound pressure is located in the entire small ball.

[0031] Further, the radius of the large ball is 24 mm, the radius of the small ball is 3 mm, and the radius ratio between the large ball and the small ball satisfies 8:1, and the photoacoustic signal is the largest. Here, the setting of the radius between the large ball and the small ball can be determined according to the actual situation, and the present application is not limited, only one preferred embodiment is given;

[0032] Further, the distance between the large ball and the small ball is 0.2mm-0.5mm, and the distance between the large ball and the small ball can be determined according to the actual situation, and the present application is not limited, only one preferred range is given.

[0033] Referring to Figure 1 and Figure 2 , the cantilever beam acoustic wave sensor 6 is placed at the end of the small ball in the double-ball coupling type photoacoustic cell 4, and a cuboid pit is formed on the cantilever beam acoustic wave sensor 6; the three edges of the bottom surface of the cuboid pit are all gaps to form a cantilever beam 7, and the cantilever beam 7 is placed at the top end of one side of the small ball to measure the maximum sound wave energy, thereby realizing detection of lower gas concentration.

[0034] Further, the cantilever beam 7 used in the structure is a silicon dioxide sheet 8 processed by MEMS technology, which is made on the silicon dioxide sheet by laser processing technology, one side of the cantilever beam 7 is fixed, and the other three sides can freely vibrate (as shown in Figure 2 ), which can realize detection of sound signals by combining F-P interference demodulation method.

[0035] The double-ball coupling type photoacoustic cell 4 has five resonance frequencies of 4520 Hz, 6990 Hz, 7800 Hz, 9820 Hz and 9990 Hz below 10000 Hz, and can be used for simultaneous detection of five kinds of environmental pollution gases such as CO2, CO, CH4, C2H2 and H2S.

[0036] Figure 3 For the COMSOL simulation diagram of the double-ball coupling type photoacoustic cell 4, wherein Figure 3 The abscissa represents the frequency, and the ordinate represents the size of the photoacoustic signal. It can be seen from the simulation results in the figure that there are five peaks, which are used to measure five kinds of gases, that is, at the resonance frequencies of 4520 Hz, 6990 Hz, 7800 Hz, 9820 Hz and 9990 Hz, the size of the corresponding photoacoustic signal can be measured.

[0037] The specific operation principle of the application is as follows:

[0038] The collimator 1 and the 3D printed shell 2 are fixedly connected by adhesive, which is used for precise calibration of the excitation light source; the double-ball coupling type photoacoustic cell 4 is used for generating and amplifying the photoacoustic signal; the gas inlet hole 3 and the gas outlet hole 5 of the 3D printed shell 2 are respectively used for gas input and discharge, to ensure that the gas exchange is carried out smoothly; the cantilever beam acoustic wave sensor 6 is placed at the end of the small ball of the double-ball coupling type photoacoustic cell 4, which is used to detect the maximum photoacoustic signal. The excitation light source transmits the excitation light to the photoacoustic cavity through the collimator 1, and the photoacoustic effect occurs with the gas to generate a photoacoustic signal, which is amplified in the small ball of the double-ball coupling type photoacoustic cell 4. The cantilever beam acoustic wave sensor 6 receives and collects this signal, and finally transmits the signal to the computer for processing, and then the concentration information of the gas to be measured is obtained.

[0039] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A dual-ball coupling type photoacoustic multi-gas sensor based on, The application relates to a double-ball coupling type photoacoustic cell, which comprises a shell (2) provided with a double-ball coupling type photoacoustic cell (4) in the interior of the shell (2), wherein the double-ball coupling type photoacoustic cell (4) comprises a large ball and a small ball which are coupled to each other, the maximum sound pressure is located in the whole small ball, a cantilever beam sound wave sensor (6) for detecting a photoacoustic signal is arranged at the end of the small ball, and a cantilever beam (7) positively correlated with the gas concentration in the interior of the photoacoustic cell is arranged in the cantilever beam sound wave sensor (6). ​ 2.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: A rectangular pit is formed in the cantilever beam sound wave sensor (6), the bottom surface of the rectangular pit forms the cantilever beam (7), and the cantilever beam (7) is located at the top end of one side of the small ball. 3.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: The shell (2) is connected with a collimator (1) at one end away from the cantilever beam sound wave sensor (6) through a gluing mode. 4.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: The cantilever beam (7) is a silicon dioxide sheet (8) processed by MEMS technology. 5.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 4, wherein: One side of the cantilever beam (7) is fixed, and the other three sides can freely vibrate. 6.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: Gas inlet holes (3) and gas outlet holes (5) which are communicated with the double-ball coupling type photoacoustic cell (4) are formed at two ends of the shell (2). 7.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: When the ratio between the radius of the large ball and the radius of the small ball is 8:1, the photoacoustic signal is maximum. 8.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 7, characterized by: The radius of the large ball is 24 mm, and the radius of the small ball is 3 mm. 9.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: The distance between the large ball and the small ball is 0.2-0.5 mm. 10.The dual-ball coupling type photoacoustic multi-gas sensor according to claim 1, wherein: The double-ball coupling type photoacoustic cell (4) has five resonance frequencies below 10000 Hz, and is used for simultaneously detecting five kinds of gases.

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