A photoacoustic sensor and gas detection apparatus
By placing the light source module outside the photoacoustic cell and connecting it to the photoacoustic cavity through the holes in the side wall of the photoacoustic cell, the problem of the overall size of the photoacoustic sensor is solved, realizing the miniaturization and integration of the photoacoustic sensor, which is suitable for accurate gas detection in portable and wearable devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SUZHOU RUIXIN MICROSYSTEM TECH CO LTD
- Filing Date
- 2025-06-19
- Publication Date
- 2026-08-04
AI Technical Summary
Existing photoacoustic sensors have a large overall size due to the light source being built into the photoacoustic cell, making them difficult to integrate into portable and wearable devices.
The light source module is placed outside the photoacoustic pool and connected to the photoacoustic cavity through a hole in the side wall of the photoacoustic pool. The light source module is placed flat outside the photoacoustic pool, and the light emitted by the light source enters the photoacoustic cavity through the hole. Combined with the sound wave acquisition module, gas detection is realized.
It achieves miniaturization and integration of photoacoustic sensors, making them suitable for accurate gas detection in portable devices, wearable devices, and even mobile phones and tablets.
Smart Images
Figure CN224594469U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of sensor technology, and in particular to a photoacoustic sensor and a gas detection device. Background Technology
[0002] A photoacoustic sensor is a high-precision gas detection sensor based on the photoacoustic effect. By combining optical excitation and acoustic signal detection, it enables qualitative and quantitative analysis of specific gas components, and has significant application potential in fields such as medicine, environmental monitoring, and industrial safety. When light of a specific wavelength (usually infrared light or laser) irradiates gas molecules, the gas absorbs the light energy and is excited to transition to a higher energy state. Then, it converts energy into kinetic energy through a non-radiative transition from the higher energy state to a lower energy state, causing the gas to thermally expand. This process can be periodically generated by modulating the light source, thus forming an acoustic pressure wave signal. The strength of the signal is positively correlated with the concentration of the gas molecules being measured. The generated acoustic signal is the photoacoustic signal. The intensity of the acoustic signal is proportional to the concentration of the target gas, thereby achieving accurate gas detection.
[0003] Existing photoacoustic sensors typically embed the light source within the photoacoustic cell, resulting in a large overall size of the photoacoustic cell, which is not conducive to integrating the photoacoustic sensor into small devices such as portable devices and wearable devices.
[0004] Therefore, in view of the above-mentioned technical problems, how to provide a miniaturized and integrated photoacoustic sensor is a technical problem that needs to be solved by those skilled in the art. Utility Model Content
[0005] The purpose of this application is to provide a photoacoustic sensor and a gas detection device, which reduces the normal size of the photoacoustic cell and realizes the overall miniaturization and integration of the photoacoustic sensor.
[0006] To achieve the above objectives, this application provides a photoacoustic sensor, comprising:
[0007] A photoacoustic cell, including a photoacoustic cavity, wherein the sidewall of the photoacoustic cell has a hole communicating with the photoacoustic cavity;
[0008] An acoustic wave acquisition module, built into the photoacoustic cavity, is used to acquire acoustic wave signals within the photoacoustic cavity;
[0009] A light source module is placed flat outside the photoacoustic pool and connected to the hole. The light emitted by the light source module is directed toward the hole and enters the photoacoustic cavity through the hole.
[0010] Preferably, there are multiple light source modules distributed around the photoacoustic pool, and the multiple light source modules are used to emit light of different wavelengths.
[0011] Preferably, the system further includes a sensor substrate, the photoacoustic cell is fixed on the sensor substrate and surrounds the sensor substrate to form the photoacoustic cavity, the acoustic wave acquisition module is mounted on the sensor substrate, and both the light source module and the acoustic wave acquisition module are electrically connected to the sensor substrate.
[0012] Preferably, the sound wave acquisition module includes a condenser microphone or a piezoelectric sensor, and a sound inlet channel is provided on the sensor substrate located below the condenser microphone.
[0013] Preferably, the upper wall of the photoacoustic cell is provided with vents for gas to enter and exit, and the vents are covered with a breathable membrane to filter particulate matter and noise in the gas.
[0014] Preferably, the light source module includes:
[0015] A tube shell, one end of which is closed and the other end is open, with the open end of the tube shell fixedly disposed on the photoacoustic cell on the outer periphery of the hole;
[0016] A filter, wherein the outer circumferential edge of the filter is sealed to the tube shell, thereby forming a sealed space between the filter and the closed end of the tube shell;
[0017] A light source is fixedly disposed in the sealed space and attached to the inner wall of the closed end of the tube shell. The light source is directed toward the open end of the tube shell and is electrically connected to the sensor substrate.
[0018] Preferably, the filters in different light source modules have different filtering wavelengths.
[0019] Preferably, the light source module further includes a light source substrate electrically connected to the sensor substrate, the closed end of the tube shell is fixed on the light source substrate, and the light source is electrically connected to the light source substrate.
[0020] Preferably, the tube shell is attached to the sensor substrate, and the tube shell wall is provided with a conductive part that electrically connects the light source and the sensor substrate.
[0021] A gas detection device comprising the photoacoustic sensor described in any one of the preceding claims.
[0022] Unlike existing technologies that place the light source module inside the photoacoustic cell, this application places the light source module outside the photoacoustic cell, which reduces the overall size of the photoacoustic cell. Furthermore, the flat placement of the light source module reduces the overall height of the sensor, making it more suitable for integration and miniaturization. This allows it to be applied in portable devices, wearable devices, and even mobile phones and tablets. The holes on the side wall of the photoacoustic cell are connected to the light source module, allowing the light emitted by the light source module to enter the photoacoustic cavity through the holes and work with the acoustic wave acquisition module inside the photoacoustic cavity to achieve accurate gas detection. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0024] Figure 1 This is a schematic diagram of the photoacoustic sensor structure provided in the embodiments of this application;
[0025] Figure 2 This is a top view of the photoacoustic sensor provided in an embodiment of this application;
[0026] Figure 3 This is a schematic diagram of another structure of the photoacoustic sensor provided in the embodiments of this application;
[0027] Figure 4 This is a cross-sectional view of the light source module provided in an embodiment of this application;
[0028] Figure 5 This is a three-dimensional structural diagram of the light source module provided in an embodiment of this application.
[0029] In the diagram: 1-Photoacoustic cell; 2-Acoustic wave acquisition module; 3-Light source module; 4-Sensor substrate; 5-Vacuum membrane;
[0030] 11-Photoacoustic cavity; 12-Ventilation hole; 13-Hole;
[0031] 31-Tube shell; 32-Filter; 33-Light source; 34-Light source substrate; 311-Limiting step; 312-Positioning part; 313-Pad; 321-First filter; 322-Second filter;
[0032] 41 - Audio input channel. Detailed Implementation
[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and 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.
[0034] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is used only for the convenience of describing this application and for simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0035] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0036] like Figure 1 As shown, in this embodiment, a photoacoustic sensor is provided, including a photoacoustic cell 1, a sound wave acquisition module 2, and a light source module 3. The photoacoustic cell 1 is a closed container with a photoacoustic cavity 11 inside, where the photoacoustic effect occurs. The shape of the photoacoustic cell 1 can be a regular shape such as a cuboid, cube, or sphere, or it can be an irregular shape; no particular restrictions are placed here. However, considering the overall miniaturization and flattening of the photoacoustic sensor, a cuboid shape is preferred for the photoacoustic cell 1. With a fixed volume of the photoacoustic cavity 11, the cuboid is lower in height than a cube or a sphere, making it easier to miniaturize and flatten, and thus applicable to portable devices, wearable devices, and even mobile phones and tablets.
[0037] The photoacoustic cell 1 has a hole 13 on its side wall that communicates with the photoacoustic cavity 11. The hole 13 can be round or square, etc. The light source module 3 is placed flat outside the photoacoustic cell 1 and connected to the hole 13. The connection method can be adhesive or welding to ensure a stable connection between the two. It should be noted that the above-mentioned flat placement means that the light source module 3 and the photoacoustic cell 1 can be placed sequentially along the length of the photoacoustic cell 1, so as to minimize the influence of the light source module 3 on the height of the sensor. In addition, when the light source module 3 is connected to the hole 13, light leakage at the connection point should be avoided to prevent unwanted wavelengths of light from entering the photoacoustic cavity 11.
[0038] Compared to placing the light source module 3 inside the photoacoustic cell 1, placing the light source module 3 outside the photoacoustic cell 1 in this embodiment can effectively reduce the volume of the photoacoustic cavity 11 occupied by the light source module 3, allowing the volume of the photoacoustic cell 1 to be further reduced, which is more conducive to the miniaturization and integration of the photoacoustic sensor.
[0039] Furthermore, the light emitted by the light source module 3 should be directed towards the aperture 13, allowing the light to pass through the aperture 13 and enter the photoacoustic cavity 11. The gas molecules within the photoacoustic cavity 11 will absorb light of a specific wavelength and be excited to transition to a higher energy state. Then, they will convert energy into kinetic energy through a non-radiative transition from the high-energy state to a low-energy state, causing the gas to thermally expand. This process can be generated periodically by the light source module 3, thereby forming an acoustic pressure wave signal in the photoacoustic cavity 11. The strength of the signal is positively correlated with the concentration of the gas molecules. The acoustic wave signal is acquired by the acoustic wave acquisition module 2 inside the photoacoustic cavity 11, thus achieving accurate detection of the gas and precise measurement of its concentration.
[0040] In summary, by placing the light source module 3 outside the photoacoustic cell 1, the overall size of the photoacoustic cell 1 can be reduced. Furthermore, by placing the light source module 3 horizontally, the overall height of the sensor can be reduced, which is more conducive to integration and miniaturization. This allows it to be applied to portable devices, wearable devices, and even mobile phones and tablets. The holes 13 on the side wall of the photoacoustic cell 1 are connected to the light source module 3, allowing the light emitted by the light source module 3 to enter the photoacoustic cavity 11 through the holes 13. Together with the acoustic wave acquisition module 2 inside the photoacoustic cavity 11, it enables accurate detection of the gas.
[0041] Furthermore, the number of light source modules 3 can be one or more, please refer to [reference needed]. Figure 2 Multiple light source modules 3 can be distributed around the photoacoustic cell 1. Holes 13 corresponding to each light source module 3 are opened around the photoacoustic cell 1 to ensure that the light emitted by each light source module 3 can enter the photoacoustic cavity 11. Each light source module 3 can emit light of different wavelengths, and each wavelength of light corresponds to the absorption peak of a different gas. Therefore, each module corresponds to the detection of a gas, thereby enabling the photoacoustic sensor to detect one or more different gases.
[0042] The photoelectric sensor also includes a sensor substrate 4, which can be a PCB (printed circuit board). The photoacoustic cell 1 is fixed on the sensor substrate 4. The photoacoustic cell 1 can be enclosed with the sensor substrate 4 to form the aforementioned photoacoustic cavity 11, or the photoacoustic cell 1 can enclose itself to form the aforementioned photoacoustic cavity 11, both of which fall within the protection scope of this application. However, in order to facilitate the electrical connection between the acoustic wave acquisition module 2 and the sensor substrate 4, it is preferable to use the method of enclosing the photoacoustic cell 1 and the sensor substrate 4 to form the photoacoustic cavity 11. In this case, the acoustic wave acquisition module 2 can be directly mounted on the sensor substrate 4, and the acoustic wave acquisition module 2 is naturally located inside the photoacoustic cavity 11.
[0043] The light source module 3 is also electrically connected to the sensor substrate 4, so that the sensor substrate 4 provides voltage to the light source module 3, causing the light source module 3 to emit light.
[0044] The sound wave acquisition module 2 includes a condenser microphone and a piezoelectric sensor. The condenser microphone has high sensitivity. When using a condenser microphone, an inlet channel 41 should be set on the sensor substrate 4 below the condenser microphone so that the sound wave signal can enter the condenser microphone through the inlet channel 41, thereby achieving accurate acquisition of the sound wave signal.
[0045] In addition, a vent 12 for gas to enter and exit is provided on the upper wall of the photoacoustic cell 1. Please refer to [reference needed]. Figures 1 to 3 The photoacoustic cavity 11 can exchange gases with the outside world through the vent 12, enabling real-time detection of gases in different external environments. At the same time, a breathable membrane 5 can be covered on the vent 12 to filter particulate matter and noise in the external gas, preventing particulate matter or noise from affecting the detection accuracy of the photoacoustic sensor.
[0046] Light source module 3 includes a housing 31, a filter 32, and a light source 33. Please refer to [reference needed]. Figure 1 The tube shell 31 is closed at one end and open at the other end, and has an internal accommodating space. The tube shell 31 can be an opaque ceramic tube shell with low thermal conductivity or a plastic tube shell. Opaque means that it is not transparent to visible light and infrared light. The open end of the tube shell 31 is fixed to the photoacoustic cell 1 on the outer periphery of the hole 13. The fixing method can be adhesive or welding.
[0047] The outer circumferential edge of the filter 32 is sealed to the housing 31, thereby forming a sealed space between the filter 32 and the closed end of the housing 31. In other words, the filter 32 is disposed on the side of the housing 31 near the open end. The filter 32 can be disposed inside the housing 31 or at the open end of the housing 31. When the filter 32 is disposed inside the housing 31, the circumferential sidewall of the filter 32 can fit against the circumferential inner wall of the housing 31; when the filter 32 is disposed at the open end of the housing 31, the side of the filter 32 facing the housing 31 fits against the end face of the open end of the housing 31.
[0048] It should be noted that, regardless of the method used, a sealed space can be formed between the filter 32 and the closed end of the housing 31. The filter 32 can be sealed to the housing 31 by means of adhesive bonding, glass melting, eutectic bonding, etc. The environment in the sealed space can be air, nitrogen, or vacuum, etc. The filter 32 can be a silicon-based filter or a sapphire filter, without further restrictions.
[0049] The light source 33 is fixedly disposed in the aforementioned sealed space. The light source 33 can be a blackbody chip, an LED chip, or a laser chip, etc. It is mounted on the inner wall of the closed end of the housing 31 by means of a surface mount, and the light source 33 faces the open end of the housing 31, ensuring that the light emitted by the light source 33 can enter the photoacoustic cavity 11 through the hole 13. The light source 33 is electrically connected to the sensor substrate 4, thereby providing the operating voltage for the light source 33.
[0050] The filter 32 includes a first filter 321 and a second filter 322 fixedly disposed on the housing 31. Please refer to [reference needed]. Figure 4 The second filter 322 is sealed to the housing 31, thereby forming a sealed space between the second filter 322 and the closed end of the housing 31; furthermore, the second filter 322 is closer to the open end of the housing 31 than the first filter 321, so the first filter 321 can be fixed in the sealed space.
[0051] Furthermore, in addition to being located in the aforementioned enclosed space, the light source 33 is also situated between the first filter 321 and the closed end of the housing 31. That is, along the length of the housing 31, the second filter 322, the first filter 321, and the light source 33 are sequentially distributed. The light source 33 faces the open end of the housing 31, thereby allowing the light emitted by the light source 33 to pass sequentially through the first filter 321 and the second filter 322.
[0052] It should be noted that the second filter 322 can be disposed inside the housing 31 or at the open end of the housing 31. Regardless of whether it is disposed inside or at the open end of the housing 31, with the first filter 321 and the second filter 322 spaced apart, the first filter 321 must be located inside the housing 31, so that the circumferential sidewall of the first filter 321 corresponds to the inner wall of the housing 31. Therefore, when the light emitted by the light source 33 passes through the first filter 321, since the first filter 321 corresponds to the inner wall of the housing 31, light can be prevented from leaking out from the circumferential sidewall of the first filter 321. That is, by utilizing the blocking or reflection effect of the inner wall of the housing 31, light can still pass through the first filter 321, thereby filtering out unwanted wavelengths of light. At the same time, the second filter 322 can also play a further filtering role, further ensuring that unwanted wavelengths of light will not be emitted from the light source module 3.
[0053] By employing a dual-filter design, the first filter 321 is placed within the sealed space formed by the second filter 322 and the housing 31, with the sidewall of the first filter 321 corresponding to the inner wall of the housing 31. This prevents unwanted wavelengths of light (such as light from the water vapor absorption spectrum) from escaping the housing 31 due to light leakage from the filter sidewalls, thereby reducing the impact of humidity on the sensor. Simultaneously, there is sufficient spacing between the second filter 322 and the light source 33, with the first filter 321 blocking heat transfer. The spacing between the first and second filters further reduces heat transfer efficiency, resulting in minimal heat transfer to the second filter 322. Ultimately, virtually no heat is transferred through the second filter 322, significantly minimizing bottom noise caused by heat. Since ambient temperature primarily affects this bottom noise, the dual-filter packaging design eliminates it, thus preventing the influence of ambient temperature on the sensor.
[0054] Based on the dual-filter design, the aforementioned sealed space can be set as a vacuum-sealed or inert gas-sealed package to reduce the impact of air medium on photophysical performance.
[0055] Furthermore, the first filter 321, the second filter 322, and the light source 33 are arranged in parallel, and the angular error between the three cannot exceed ±5°, preferably not exceeding ±3°, and more preferably not exceeding ±1°. The light source 33 ultimately emits light from the tube housing 31 at an angle of 80-160°, preferably 100-160°.
[0056] In some embodiments, the first filter 321 is a standard BP filter (a filter with a narrow bandwidth). The side facing the light source 33 is provided with a BP film, and the other side of the first filter 321 is provided with an AR film. The BP film can filter unwanted wavelengths of light, and the AR film plays a role in enhancing light transmission. The BP film faces the light source 33, and the front and back are marked on one edge of the AR film to distinguish them so as to correctly install the first filter 321.
[0057] The second filter 322 can be a standard BP filter or a double AR film filter. A double AR film filter has AR films on both sides, which can enhance light transmission. It can be seen that the first filter 321 primarily filters unwanted wavelengths of light. Based on the first filter 321, the light emitted by the light source 33 is basically or completely filtered, thus selecting the desired wavelengths. The second filter 322 can further enhance light transmission. If further filtering of unwanted wavelengths is required, the second filter 322 should be a standard BP filter.
[0058] Please refer to Figure 5The inner wall of the closed end of the tube shell 31 is provided with a positioning part 312. The positioning part 312 can be a positioning boss or a positioning icon, or a combination of a positioning boss and a positioning icon. Specifically, the positioning boss can be engaged with the light source 33 mounted on the inner wall of the closed end of the tube shell 31 to limit the position of the light source 33 and ensure that the light source 33 can be stably set. The positioning icon can be an etched pit icon, an inkjet icon, a laser marking, etc. The automatic placement equipment can align the icon with high precision to achieve accurate positioning of the automatic placement equipment, thereby completing the placement of the light source 33. In addition, the positioning icon can also be etched on the positioning boss to achieve the dual functions of positioning the light source 33 and positioning the automatic placement equipment.
[0059] In addition, the inner wall of the shell 31 is provided with circumferentially distributed limiting steps 311, please refer to Figure 5 The side of the first filter 321 facing the light source 33 abuts against the limiting step 311. At the same time, the circumferential sidewall of the first filter 321 is attached to the inner wall of the tube shell 31. The first filter 321 is fixedly sealed at the limiting step 311. The fixing and sealing method can be adhesive bonding, eutectic welding, glass sealing, etc. The above methods can prevent light leakage from the sidewall of the first filter 321, which would cause unwanted wavelength light (such as light from the water vapor absorption spectrum) to be emitted from the tube shell 31, thereby further reducing the influence of temperature and humidity and improving the detection accuracy of the corresponding gas.
[0060] Furthermore, the side of the second filter 322 facing the first filter 321 abuts against the end of the opening of the tube housing 31 and is fixedly sealed to the tube housing 31. The fixing and sealing method can refer to the method of the first filter 321 described above, and will not be repeated here.
[0061] To improve the sensor signal strength, a reflective coating can be added to the inner wall of the housing 31 to reduce the absorption of light emitted from the light source 33 by the housing 31. The coating can be a polymer material coating or a metal coating. The surface roughness of the coating should be less than 50 μm, preferably less than 10 μm, and more preferably less than 1 μm. The infrared reflectivity of the coating should be greater than 60%, preferably greater than 80%, and more preferably greater than 85%. The coating method can be spraying, physical vapor deposition, or chemical vapor deposition; these will not be elaborated here, as they all fall within the scope of protection of this application.
[0062] In order to meet the different wavelengths of light emitted by different light source modules 3, the filters 32 in different light source modules 3 should have different filtering wavelengths, so that each light source module 3 corresponds to the detection of a gas.
[0063] In addition, please refer to Figure 1The light source module 3 also includes a light source substrate 34 electrically connected to the sensor substrate 4. The light source substrate 34 can be a PCB or a flexible FPC (flexible printed circuit board). The closed end of the tube shell 31 is fixed on the light source substrate 34, or in other words, the light source substrate 34 is fixed on the closed end of the tube shell 31. Furthermore, when the light source substrate 34 is a PCB, both the closed end and the open end of the tube shell 31 can be fixed, thus achieving a high level of stability. When the light source substrate 34 is an FPC, the tube shell 31 can provide stable support for the light source substrate 34.
[0064] The light source 33 is electrically connected to the light source substrate 34, thereby realizing the electrical connection between the light source 33 and the sensor substrate 4. Specifically, a pad 313 can be provided on the inner wall of the closed end of the housing 31. The light source 33 is electrically connected to the pad 313 through wire bonding technology. The corresponding pad 313 can be electrically connected to the light source substrate 34 by soldering. Similarly, the light source substrate 34 can also be electrically connected to the sensor substrate 4 by soldering, thereby realizing the electrical connection between the light source 33 and the sensor substrate 4.
[0065] In some embodiments, the light source substrate 34 described above may be omitted. Please refer to [reference needed]. Figure 3 The housing 31 can be mounted on the sensor substrate 4. That is, a conductive part that electrically connects the light source 33 and the sensor substrate 4 is provided on the wall of the housing 31. The conductive part is directly located on the wall of the housing 31, which saves the space of setting the light source substrate 34 and further reduces the cost.
[0066] A pulse voltage is supplied to the light source 33 via the sensor substrate 4, causing the light source 33 to generate light corresponding to the pulse signal. This light passes through the filter 32 to form wavelength light corresponding to the absorption peak of the gas. The light then enters the photoacoustic cavity 11 through the hole 13 on the side wall of the photoacoustic cell 1 and is continuously reflected and absorbed by the corresponding gas. This excites the gas to be detected to transition to a high-energy state, and then converts the energy into kinetic energy through a non-radiative transition from the high-energy state to a low-energy state, causing the gas to thermally expand. This process can be periodically generated by the light source module 3, thus forming an acoustic pressure wave signal in the photoacoustic cavity 11. The strength of the signal is positively correlated with the concentration of the gas molecules being measured. The generated acoustic signal (i.e., photoacoustic signal) enters the acoustic wave acquisition module 2 through the sound inlet channel 41. By processing the acoustic signal received by the acoustic wave acquisition module 2, the concentration of the corresponding gas can be detected.
[0067] This application also provides a gas detection device, which includes the aforementioned photoacoustic sensor.
[0068] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.
[0069] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A photoacoustic sensor, characterized in that, include: The photoacoustic pool (1) includes a photoacoustic cavity (11), and the side wall of the photoacoustic pool (1) is provided with a hole (13) communicating with the photoacoustic cavity (11). The acoustic wave acquisition module (2) is built into the photoacoustic cavity (11) and is used to acquire acoustic wave signals in the photoacoustic cavity (11); The light source module (3) is placed flat outside the photoacoustic pool (1) and connected to the hole (13). The light emitted by the light source module (3) is directed toward the hole (13) and enters the photoacoustic cavity (11) through the hole (13).
2. The photoacoustic sensor according to claim 1, characterized in that, The number of light source modules (3) is multiple and they are distributed around the photoacoustic pool (1). The multiple light source modules (3) are used to emit light of different wavelengths.
3. The photoacoustic sensor according to claim 2, characterized in that, It also includes a sensor substrate (4), the photoacoustic cell (1) is fixed on the sensor substrate (4) and surrounds the sensor substrate (4) to form the photoacoustic cavity (11), the acoustic wave acquisition module (2) is attached to the sensor substrate (4), and the light source module (3) and the acoustic wave acquisition module (2) are both electrically connected to the sensor substrate (4).
4. The photoacoustic sensor according to claim 3, characterized in that, The acoustic wave acquisition module (2) includes a condenser microphone or a piezoelectric sensor, and the sensor substrate (4) located below the condenser microphone is provided with an acoustic channel (41).
5. The photoacoustic sensor according to claim 1, characterized in that, The upper wall of the photoacoustic cell (1) is provided with a vent (12) for gas to enter and exit. The vent (12) is covered with a breathable membrane (5) to filter particulate matter and noise in the gas.
6. The photoacoustic sensor according to claim 3, characterized in that, The light source module (3) includes: The tube shell (31) is closed at one end and open at the other end. The open end of the tube shell (31) is fixedly installed on the photoacoustic cell (1) on the outer periphery of the hole (13). A filter (32) is provided, with its outer circumferential edge sealed to the housing (31), thereby forming a sealed space between the filter (32) and the closed end of the housing (31). The light source (33) is fixed in the sealed space and attached to the inner wall of the closed end of the tube shell (31). The light source (33) faces the open end of the tube shell (31). The light source (33) is electrically connected to the sensor substrate (4).
7. The photoacoustic sensor according to claim 6, characterized in that, The filters (32) in different light source modules (3) have different filtering wavelengths.
8. The photoacoustic sensor according to claim 6, characterized in that, The light source module (3) further includes a light source substrate (34) electrically connected to the sensor substrate (4), the closed end of the tube shell (31) is fixed on the light source substrate (34), and the light source (33) is electrically connected to the light source substrate (34).
9. The photoacoustic sensor according to claim 6, characterized in that, The tube shell (31) is attached to the sensor substrate (4), and the tube wall of the tube shell (31) is provided with a conductive part that electrically connects the light source (33) and the sensor substrate (4).
10. A gas detection device, characterized in that, Includes the photoacoustic sensor according to any one of claims 1-9.