A downhole coal mine dust concentration sensor based on surface acoustic wave

Abstract

The application discloses a downhole coal mine dust concentration sensor based on a surface acoustic wave, which comprises a piezoelectric substrate, a first interdigital transducer, a second interdigital transducer, a graphene layer and a circuit board, the first interdigital transducer and the second interdigital transducer are arranged on the piezoelectric substrate at intervals, the graphene layer is arranged on the piezoelectric substrate and used for adsorbing dust, the circuit board is used for emitting a radio frequency electric signal to the first interdigital transducer, and the second interdigital transducer is used for receiving a surface acoustic wave generated by the piezoelectric substrate and converting the surface acoustic wave into an electric signal which is delivered to the circuit board. The application can realize real-time monitoring of the coal mine dust concentration, timely discovery of abnormal conditions and provision of guarantee for mine safety production. The surface acoustic wave sensor is very sensitive to changes in dust concentration and can accurately detect slight changes. Compared with traditional optical and electrical dust detection methods, the surface acoustic wave technology has strong anti-electromagnetic interference capability and is more suitable for complex mine environments.

Description

Technical Field

[0001] This invention relates to the field of dust concentration sensor technology, and specifically to a dust concentration sensor for underground coal mines based on surface acoustic waves. Background Technology

[0002] Coal mines, as an important geological resource, play a vital role in energy supply and industrial production. However, during coal mining, drilling operations often generate large amounts of coal dust. This dust not only poses a serious threat to miners' health, such as causing occupational diseases like pneumoconiosis and respiratory illnesses, but can also lead to dust explosions at certain concentrations and in certain environments, endangering mine safety. Therefore, the detection and control of coal mine dust has become a crucial aspect of ensuring safe production in mines. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, embodiments of the present invention propose a dust concentration sensor for underground coal mines based on surface acoustic waves.

[0005] The surface acoustic wave-based dust concentration sensor for underground coal mines according to this invention includes a piezoelectric substrate, a first interdigital transducer, a second interdigital transducer, a graphene layer, and a circuit board. The first and second interdigital transducers are spaced apart on the piezoelectric substrate along its length. The graphene layer is disposed on the piezoelectric substrate and located between the first and second interdigital transducers for adsorbing dust.

[0006] The circuit board is electrically connected to the first interdigital transducer and the second interdigital transducer respectively. The circuit board is used to transmit radio frequency electrical signals to the first interdigital transducer so that the first interdigital transducer excites the piezoelectric substrate to generate mechanical vibration and surface acoustic waves. The second interdigital transducer is used to receive the surface acoustic waves generated by the piezoelectric substrate and convert them into electrical signals and transmit them to the circuit board. The circuit board is also used to process the electrical signals sent by the second interdigital transducer and determine the change in dust concentration based on the change in the electrical signals.

[0007] In some embodiments, the graphene layer is located on the same side of the piezoelectric substrate as the first interdigital transducer and the second interdigital transducer.

[0008] In some embodiments, the graphene layer is a porous graphene layer.

[0009] In some embodiments, the first interdigital transducer includes a first bus electrode and a plurality of first interdigital electrodes, the first bus electrode extending along the length direction of the piezoelectric substrate, the plurality of first interdigital electrodes being spaced apart on the first bus electrode along the length direction of the first bus electrode, and the first interdigital electrodes extending along the width direction of the piezoelectric substrate.

[0010] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor of the present invention further includes a first reflective grid, the first reflective grid including a first busbar and a plurality of first grid electrodes, the first busbar extending along the length direction of the piezoelectric substrate and spaced apart from the first busbar electrodes, the plurality of first grid electrodes being spaced apart on the first busbar along the length direction of the piezoelectric substrate, the first grid electrodes extending along the width direction of the piezoelectric substrate, and the first grid electrodes and the first interdigitated electrodes being arranged alternately in sequence.

[0011] In some embodiments, the second interdigital transducer includes a second bus electrode and a plurality of second interdigital electrodes, the second bus electrode extending along the length direction of the piezoelectric substrate, the plurality of second interdigital electrodes being spaced apart on the second bus electrode along the length direction of the second bus electrode, and the second interdigital electrodes extending along the width direction of the piezoelectric substrate.

[0012] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor of the present invention further includes a second reflective grating. The second reflective grating includes a second busbar and a plurality of second grating electrodes. The second busbar extends along the length direction of the piezoelectric substrate and is spaced apart from the second busbar electrodes. The plurality of second grating electrodes are spaced apart on the second busbar along the length direction of the piezoelectric substrate. The second grating electrodes extend along the width direction of the piezoelectric substrate. The second grating electrodes and the second interdigitated electrodes are arranged alternately in sequence.

[0013] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor of the present invention further includes a base plate and a protective cover. The protective cover is detachably mounted on the base plate, and a protective cavity is defined between the protective cover and the base plate. The protective cover has a plurality of spaced dust passage holes, and the piezoelectric substrate and the circuit board are disposed in the protective cavity.

[0014] In some embodiments, the protective cover has a wire-passing hole for the power cord to enter the protective cavity.

[0015] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor of the present invention further includes a first support frame and a second support frame, the first support frame and the second support frame being spaced apart on the base plate and located within the protective cavity, the piezoelectric substrate being disposed on the first support frame, and the circuit board being disposed on the second support frame.

[0016] In use, the underground coal mine dust concentration sensor of this invention works as follows: when the circuit board transmits an radio frequency (RF) signal to the first interdigital transducer, the alternation of the first interdigital transducer stimulates the periodic expansion and contraction of the piezoelectric substrate. This process generates surface acoustic waves (SAWs), which propagate along the length of the piezoelectric substrate and pass through the porous graphene layer. If dust is present in the air, it diffuses into the porous graphene layer, maintaining a concentration consistent with the airborne dust concentration. At this point, the SAW signal attenuates, with the attenuation magnitude proportional to the dust concentration. After attenuation, the SAW signal passes through the second interdigital transducer, where it is converted into an RF signal and transmitted to the circuit board. The circuit board can then determine the current airborne dust concentration by monitoring changes in the RF signal.

[0017] The underground coal mine dust concentration sensor of this invention enables real-time monitoring of coal mine dust concentration, timely detection of anomalies, and provides a guarantee for safe mine production. The surface acoustic wave (SAW) sensor is highly sensitive to changes in dust concentration and can accurately detect minute variations. Compared with traditional optical and electrical dust detection methods, SAW technology has strong resistance to electromagnetic interference and is more suitable for complex mine environments. This invention is less affected by environmental factors such as temperature and humidity within the mine, providing more stable measurement results. SAW sensors typically feature low power consumption, which is beneficial for long-term operation in energy-limited environments such as underground mines. Graphene, as a sensitive material, has excellent chemical stability and mechanical strength, ensuring the long-term stability of the sensor. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the dust concentration sensor according to an embodiment of the present invention.

[0019] Figure 2 This is a cross-sectional view of the dust concentration sensor according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the internal structure of the dust concentration sensor according to an embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the installation of the piezoelectric substrate according to an embodiment of the present invention.

[0022] Figure 5 This is a flowchart illustrating the operation of the dust concentration sensor according to an embodiment of the present invention.

[0023] Figure label:

[0024] 100. Dust concentration sensor; 1. Piezoelectric substrate; 2. First interdigital transducer; 201. First busbar electrode; 202. First interdigital electrode; 3. Second interdigital transducer; 301. Second busbar electrode; 302. Second interdigital electrode; 4. Graphene layer; 5. Circuit board; 6. First reflective grid; 601. First busbar grid; 602. First grid bar electrode; 7. Second reflective grid; 701. Second busbar grid; 702. Second grid bar electrode; 8. Base plate; 9. Protective cover; 901. Dust passage hole; 902. Wire passage hole; 10. Protective cavity; 11. First support frame; 12. Second support frame. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0026] like Figures 1 to 5 As shown, the underground coal mine dust concentration sensor 100 of this embodiment includes a piezoelectric substrate 1, a first interdigital transducer 2, a second interdigital transducer 3, a graphene layer 4, and a circuit board 5. The first interdigital transducer 2 and the second interdigital transducer 3 are spaced apart on the piezoelectric substrate 1 along its length. The graphene layer 4 is disposed on the piezoelectric substrate 1 and located between the first interdigital transducer 2 and the second interdigital transducer 3, and is used to adsorb dust.

[0027] Circuit board 5 is electrically connected to the first interdigital transducer 2 and the second interdigital transducer 3. Circuit board 5 is used to transmit radio frequency electrical signals to the first interdigital transducer 2, so that the first interdigital transducer 2 excites the piezoelectric substrate 1 to generate mechanical vibration and surface acoustic waves. The second interdigital transducer 3 is used to receive the surface acoustic waves generated by the piezoelectric substrate 1 and convert them into electrical signals and send them to circuit board 5. Circuit board 5 is also used to process the electrical signals sent by the second interdigital transducer 3 and determine the change in dust concentration based on the changes in the electrical signals.

[0028] The piezoelectric substrate 1 utilizes the piezoelectric effect; applying a voltage to the substrate generates mechanical vibration, and vice versa. The piezoelectric substrate 1 is the key component for generating and receiving surface acoustic waves (SAWs). The first interdigital transducer 2 is the device for exciting SAWs; it generates corresponding mechanical vibrations by applying a radio frequency signal to the piezoelectric substrate 1, thereby forming SAWs on the surface of the substrate 1. The second interdigital transducer 3 is located in the propagation path of the SAWs, used to receive the propagating SAWs and convert them into electrical signals. Graphene, due to its excellent physical properties, such as high specific surface area and good adsorption properties, is used to adsorb coal mine dust. The graphene layer 4 is located between the first and second interdigital transducers 3; the propagation speed of SAWs changes due to dust adsorption as they pass through the graphene layer 4. The circuit board 5 is responsible for controlling the transmission and reception of signals, and simultaneously processing the electrical signals from the second interdigital transducer 3. By analyzing the changes in the electrical signals, the dust concentration can be determined.

[0029] Specifically, in use, the underground coal mine dust concentration sensor 100 of this embodiment of the invention, when the circuit board 5 transmits an radio frequency signal to the first interdigital transducer 2, the alternation of the first interdigital transducer 2 will stimulate the piezoelectric substrate 1 to periodically expand and contract. During this process, surface acoustic waves (SAWs) are generated, propagating along the length of the piezoelectric substrate 1 and passing through the porous graphene layer 4. If dust is present in the air, the dust will diffuse into the porous graphene layer 4, maintaining the same dust concentration as in the air. At this time, the SAW signal will attenuate, and the attenuation amplitude is proportional to the dust concentration. When the attenuated SAW signal passes through the second interdigital transducer 3, the SAW signal is converted into a radio frequency signal and transmitted to the circuit board 5. The circuit board 5 can then obtain the current dust concentration in the air by monitoring the changes in the radio frequency signal.

[0030] The underground coal mine dust concentration sensor 100 of this invention enables real-time monitoring of coal mine dust concentration, timely detection of anomalies, and provides a guarantee for safe mine production. Surface acoustic wave (SAW) sensors are highly sensitive to changes in dust concentration and can accurately detect minute variations. Compared with traditional optical and electrical dust detection methods, SAW technology has strong resistance to electromagnetic interference and is more suitable for complex mine environments. This invention is less affected by environmental factors such as temperature and humidity within the mine, providing more stable measurement results. SAW sensors typically feature low power consumption, which is beneficial for long-term operation in energy-limited environments such as underground mines. Graphene, as a sensitive material, has excellent chemical stability and mechanical strength, ensuring the long-term stability of the sensor.

[0031] In some embodiments, the graphene layer 4 is located on the same side of the piezoelectric substrate 1 as the first interdigital transducer 2 and the second interdigital transducer 3.

[0032] Placing all components on the same side of the piezoelectric substrate 1 simplifies the overall sensor structure and reduces manufacturing costs and complexity. This same-side arrangement facilitates integration of the sensor with other electronic components, enabling the development of miniaturized, integrated detection systems. Since surface acoustic waves (SAWs) have shorter propagation paths on the piezoelectric substrate 1, signal attenuation and reflection may be reduced, thereby improving the sensor's detection efficiency and accuracy. Placing components on the same side of the piezoelectric substrate 1 may also make sensor maintenance and replacement easier. Having the graphene layer 4 and the interdigital transducer on the same side helps reduce signal interference caused by spatial distribution, improving signal quality. This same-side layout may also improve the sensor's heat dissipation performance, as graphene has excellent thermal conductivity, facilitating rapid heat dissipation.

[0033] In some embodiments, graphene layer 4 is a porous graphene layer 4.

[0034] Porous graphene has a higher specific surface area, meaning it can provide more active sites for adsorbing dust particles, thereby improving sensor sensitivity. The porous structure facilitates gas flow and mass transfer, accelerating the diffusion of dust particles to the surface of graphene layer 4 and increasing detection speed. Porous graphene layer 4 can reduce the propagation resistance of surface acoustic waves, minimizing signal attenuation and thus increasing the intensity of the signal received by the sensor. By adjusting the pore size and distribution of porous graphene, selective adsorption of dust particles of specific sizes can be achieved, increasing the selectivity and accuracy of detection.

[0035] In some embodiments, the first interdigital transducer 2 includes a first bus electrode 201 and a plurality of first interdigital electrodes 202. The first bus electrode 201 extends along the length direction of the piezoelectric substrate 1, and the plurality of first interdigital electrodes 202 are spaced apart on the first bus electrode 201 along the length direction of the first bus electrode 201. The first interdigital electrodes 202 extend along the width direction of the piezoelectric substrate 1.

[0036] like Figure 3 and Figure 4 As shown, the first bus electrode 201 is an electrode extending along the length of the piezoelectric substrate 1, serving to collect electrical signals. The bus electrode is typically wide, providing a stable current supply. Multiple interdigitated electrodes 202 are spaced apart along the length of the first bus electrode 201, each extending along the width of the piezoelectric substrate 1. These electrodes form a series of staggered "interdigitations," which, when a voltage is applied, can excite or receive surface acoustic waves (SAWs) on the piezoelectric substrate 1. The design of the interdigitated electrodes effectively converts electrical signals into mechanical energy, thereby exciting SAWs on the piezoelectric substrate 1. The staggered arrangement of multiple interdigitated electrodes increases the area for exciting or receiving SAWs, improving the transduction efficiency.

[0037] In some embodiments, the underground coal mine dust concentration sensor 100 of the present invention further includes a first reflective grating 6, which includes a first busbar 601 and a plurality of first grid electrodes 602. The first busbar 601 extends along the length direction of the piezoelectric substrate 1 and is spaced apart from the first busbar electrodes 201. The plurality of first grid electrodes 602 are spaced apart on the first busbar 601 along the length direction of the piezoelectric substrate 1. The first grid electrodes 602 extend along the width direction of the piezoelectric substrate 1, and the first grid electrodes 602 and the first interdigitated electrodes 202 are arranged alternately in sequence.

[0038] The first reflection grating 6 is a component used to control the propagation and reflection of surface acoustic waves (SAWs). It consists of first busbars 601 and multiple first grating electrodes 602. The first reflection grating 6 is designed to enhance the reflection efficiency of SAWs, allowing more sound waves to be reflected back to the transducer, thereby increasing the intensity of the detected signal. By precisely designing the spacing and width of the first grating electrodes 602, the propagation path of SAWs on the piezoelectric substrate 1 can be controlled, avoiding unnecessary energy loss. The structure of the first reflection grating 6 helps to improve the directionality of SAW propagation and reduce energy loss due to beam diffusion.

[0039] In some embodiments, the second interdigital transducer 3 includes a second bus electrode 301 and a plurality of second interdigital electrodes 302. The second bus electrode 301 extends along the length direction of the piezoelectric substrate 1, and the plurality of second interdigital electrodes 302 are spaced apart on the second bus electrode 301 along the length direction of the second bus electrode 301. The second interdigital electrodes 302 extend along the width direction of the piezoelectric substrate 1.

[0040] like Figure 3 and Figure 4 As shown, the second bus electrode 301 is an electrode extending along the length of the piezoelectric substrate 1, serving to collect electrical signals. The bus electrode is typically wide, providing a stable current supply. Multiple second interdigital electrodes 302 are spaced apart along the length of the second bus electrode 301, each extending along the width of the piezoelectric substrate 1. These electrodes form a series of staggered "interdigitations," which, when a voltage is applied, can excite or receive surface acoustic waves on the piezoelectric substrate 1. The design of the interdigital electrodes effectively converts electrical signals into mechanical energy, thereby exciting surface acoustic waves on the piezoelectric substrate 1. The staggered arrangement of multiple interdigital electrodes increases the area for exciting or receiving surface acoustic waves, improving the transduction efficiency.

[0041] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor 100 of the present invention further includes a second reflective grating 7, which includes a second busbar 701 and a plurality of second grating electrodes 702. The second busbar 701 extends along the length direction of the piezoelectric substrate 1 and is spaced apart from the second busbar electrodes 301. The plurality of second grating electrodes 702 are spaced apart on the second busbar 701 along the length direction of the piezoelectric substrate 1, and the second grating electrodes 702 extend along the width direction of the piezoelectric substrate 1. The second grating electrodes 702 and the second interdigitated electrodes 302 are arranged alternately in sequence.

[0042] The second reflection grating 7 is a component used to control the propagation and reflection of surface acoustic waves (SAWs). It consists of second busbars 701 and multiple second grating electrodes 702. The second reflection grating 7 is designed to enhance the reflection efficiency of SAWs, allowing more sound waves to be reflected back to the transducer, thereby increasing the intensity of the detected signal. By precisely designing the spacing and width of the second grating electrodes 702, the propagation path of SAWs on the piezoelectric substrate 1 can be controlled, avoiding unnecessary energy loss. The structure of the second reflection grating 7 helps to improve the directionality of SAW propagation and reduce energy loss due to beam diffusion.

[0043] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor 100 of the present invention further includes a base plate 8 and a protective cover 9. The protective cover 9 is detachably mounted on the base plate 8, and a protective cavity 10 is defined between the protective cover 9 and the base plate 8. The protective cover 9 has a plurality of spaced dust passage holes 901, and the piezoelectric substrate 1 and the circuit board 5 are disposed in the protective cavity 10.

[0044] The base plate 8 serves as the sensor's base, providing stable support and acting as the sensor's mounting interface. A protective cover 9 is detachably mounted on the base plate 8, forming a protective cavity 10 between them. The protective cover 9 is designed to protect the sensor's internal sensitive components from external environmental influences. The enclosed space defined between the protective cover 9 and the base plate 8 accommodates sensitive components such as the piezoelectric substrate 1 and the circuit board 5. The protective cover 9 features multiple spaced dust passage holes 901, allowing air and dust to pass through while preventing larger particles from directly impacting the sensor's internal components.

[0045] The protective cover 9 and base plate 8 provide a protective cavity 10 for the sensor, effectively protecting the internal components from the effects of coal or rocks in the mining environment and ensuring long-term stable operation of the sensor. The removable design of the protective cover 9 makes maintenance and replacement of the sensor's internal components more convenient and quick. The dust passage 901 allows airflow, reduces pressure differences, and also blocks larger particles, preventing them from damaging the sensor.

[0046] In some embodiments, the protective cover 9 has a wire hole 902 for the power cord to enter the protective cavity 10.

[0047] The cable guide hole 902 is a hole on the protective cover 9 specifically designed for the introduction of power cords or other cables. The cable guide hole 902 is designed to be larger than the diameter of the power cord to ensure easy passage. The design of the cable guide hole 902 simplifies the installation and maintenance of the power cord. Technicians can easily pass the power cord through the hole and connect it to the circuit board 5 inside the sensor. The cable guide hole 902 helps maintain the sealing of the protective cavity 10, preventing other harmful substances from entering, thereby protecting the internal electronic components and improving the safety and reliability of the system.

[0048] In some embodiments, the surface acoustic wave-based underground coal mine dust concentration sensor 100 of the present invention further includes a first support frame 11 and a second support frame 12. The first support frame 11 and the second support frame 12 are spaced apart on the base plate 8 and located inside the protective cavity 10. The piezoelectric substrate 1 is disposed on the first support frame 11, and the circuit board 5 is disposed on the second support frame 12.

[0049] like Figure 2 As shown, the first support frame 11 is located inside the protective cavity 10 and is used to support and fix the piezoelectric substrate 1. The design of the first support frame 11 usually takes into account the size and shape of the piezoelectric substrate 1 to ensure stable placement. The second support frame 12 is also located inside the protective cavity 10 and is used to support and fix the circuit board 5. The design of the second support frame 12 also needs to take into account the size and layout of the circuit board 5. The first support frame 11 and the second support frame 12 are arranged at intervals on the base plate 8, which ensures the independence of each component and facilitates circuit wiring and maintenance.

[0050] The support frame design enhances the stability of the piezoelectric substrate 1 and circuit board 5, preventing damage due to vibration or impact during transportation or installation. Separating the piezoelectric substrate 1 and circuit board 5 using two support frames reduces electromagnetic interference between them and facilitates individual maintenance and replacement. The spaced arrangement of the support frames provides greater flexibility for the sensor's internal layout, helping to optimize circuit wiring and the propagation path of surface acoustic waves.

[0051] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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, they should not be construed as limitations on this invention.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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, an electrical connection, or a connection that allows communication between them; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0055] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0056] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A surface acoustic wave-based dust concentration sensor for underground coal mines, characterized in that, include: piezoelectric substrate; The first interdigital transducer and the second interdigital transducer are disposed at intervals on the piezoelectric substrate along the length direction of the piezoelectric substrate. A graphene layer, which is disposed on the piezoelectric substrate and located between the first interdigital transducer and the second interdigital transducer, is used to adsorb dust. The circuit board is electrically connected to the first interdigital transducer and the second interdigital transducer respectively. The circuit board is used to transmit radio frequency electrical signals to the first interdigital transducer so that the first interdigital transducer excites the piezoelectric substrate to generate mechanical vibration and surface acoustic waves. The second interdigital transducer is used to receive the surface acoustic waves generated by the piezoelectric substrate and convert them into electrical signals and transmit them to the circuit board. The circuit board is also used to process the electrical signals transmitted by the second interdigital transducer and determine the change in dust concentration based on the change in the electrical signals. The first interdigital transducer includes a first bus electrode and a plurality of first interdigital electrodes. The first bus electrode extends along the length direction of the piezoelectric substrate, and the plurality of first interdigital electrodes are spaced apart on the first bus electrode along the length direction of the first bus electrode. The first interdigital electrodes extend along the width direction of the piezoelectric substrate. It also includes a first reflective grid, which includes a first busbar and a plurality of first grid electrodes. The first busbar extends along the length of the piezoelectric substrate and is spaced apart from the first busbar electrodes. The plurality of first grid electrodes are spaced apart on the first busbar along the length of the piezoelectric substrate. The first grid electrodes extend along the width of the piezoelectric substrate. The first grid electrodes and the first interdigitated electrodes are arranged alternately in sequence.

2. The surface acoustic wave-based dust concentration sensor for underground coal mines according to claim 1, characterized in that, The graphene layer is located on the same side of the piezoelectric substrate as the first interdigital transducer and the second interdigital transducer.

3. The surface acoustic wave-based dust concentration sensor for underground coal mines according to claim 2, characterized in that, The graphene layer is a porous graphene layer.

4. The surface acoustic wave-based underground coal mine dust concentration sensor according to claim 1, characterized in that, The second interdigital transducer includes a second bus electrode and a plurality of second interdigital electrodes. The second bus electrode extends along the length direction of the piezoelectric substrate, and the plurality of second interdigital electrodes are spaced apart on the second bus electrode along the length direction of the second bus electrode. The second interdigital electrodes extend along the width direction of the piezoelectric substrate.

5. The surface acoustic wave-based underground coal mine dust concentration sensor according to claim 4, characterized in that, It also includes a second reflective grid, which includes a second busbar and a plurality of second grid electrodes. The second busbar extends along the length of the piezoelectric substrate and is spaced apart from the second busbar. The plurality of second grid electrodes are spaced apart on the second busbar along the length of the piezoelectric substrate. The second grid electrodes extend along the width of the piezoelectric substrate. The second grid electrodes and the second interdigitated electrodes are arranged alternately in sequence.

6. The surface acoustic wave-based underground coal mine dust concentration sensor according to claim 1, characterized in that, It also includes a base plate and a protective cover, the protective cover being detachably mounted on the base plate, a protective cavity being defined between the protective cover and the base plate, the protective cover having a plurality of spaced-apart dust passage holes, and the piezoelectric substrate and the circuit board being disposed within the protective cavity.

7. The surface acoustic wave-based underground coal mine dust concentration sensor according to claim 6, characterized in that, The protective cover has a wire-passing hole for the power cord to enter the protective cavity.

8. The surface acoustic wave-based dust concentration sensor for underground coal mines according to claim 7, characterized in that, It also includes a first support frame and a second support frame, which are spaced apart on the base plate and located inside the protective cavity. The piezoelectric substrate is disposed on the first support frame and the circuit board is disposed on the second support frame.

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