A highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity

Abstract

The present application relates to the field of vibration sensing, and specifically provides a highly sensitive piezoelectric acoustic vibration sensor that combines a single contact with a cavity. The vibration sensor comprises a first structural layer, a second structural layer, a third structural layer, and a cavity. The cavity is shaped like a hollow cylinder lacking a bottom surface. The second structural layer is a disc-shaped metal material. The second structural layer is bonded and fixed to the open portion of the cavity. The second structural layer and the cavity form a sealed chamber. The third structural layer is fixedly arranged on the side of the second structural layer close to the cavity. The third structural layer is a piezoelectric material. The first structural layer is bonded and fixed to the side of the second structural layer away from the cavity. A colloidal contact is fixedly arranged on the side of the first structural layer away from the second structural layer. The sensor of the present invention has high sensitivity and strong stability.

Description

Technical Field

[0001] The present application relates to the field of vibration sensing, and in particular to a highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity. Background Art

[0002] Acoustic vibrations are inextricably linked to our daily lives. Ubiquitous, they present new challenges for detection as society progresses. Currently, the vast market opportunities presented by the consumer market make detection more crucial than ever. Acoustic vibration detection is used in various fields, such as medicine and industry, and highly sensitive detection is crucial.

[0003] Currently, there are three main types of acoustic vibration sensors: piezoelectric sensors, capacitive sensors, and magnetoelectric sensors. Capacitive sensors use capacitors as sensing elements and convert the measured value into a change in capacitance. Common examples include parallel plate capacitor sensors and cylindrical capacitors. Magnetoelectric sensors primarily utilize the principle of electromagnetic induction and have relatively high output power. Piezoelectric sensors operate primarily on the positive piezoelectric effect and are primarily used to measure various physical quantities, such as acceleration, pressure, and vibration, and their changes. Existing piezoelectric sensors are generally composed solely of piezoelectric material and a copper substrate. Since the piezoelectric material deforms solely through the deformation of the copper substrate, the degree of deformation is relatively small, resulting in minimal changes in the electrical properties of the piezoelectric material and a low sensitivity. Furthermore, sensors composed of piezoelectric material and a copper substrate have a relatively high resonant frequency, making them less effective at detecting low-frequency acoustic vibration signals, resulting in a low sensitivity.

[0004] In summary, the resonance frequency of the existing piezoelectric sensor is relatively high, and the amplitude of the piezoelectric material caused by the acoustic vibration is relatively small, resulting in a relatively low sensitivity of the existing acoustic vibration sensor. Summary of the Invention

[0005] The present invention aims to address the deficiencies in the prior art by providing a highly sensitive piezoelectric acoustic vibration sensor that combines a single contact with a cavity. The sensor comprises a colloidal contact, a first structural layer, a second structural layer, a third structural layer, a cavity, and a housing. The cavity is shaped like a hollow cylinder lacking a bottom surface. The second structural layer is a disc-shaped metal material. Specifically, the cavity wall and the second structural layer are made of copper. Copper has good ductility and high compressive strength, making it easy to deform as the second structural layer. As the cavity wall, it has good strength and can easily maintain its shape. The radius of the second structural layer is the same as the radius of the cavity bottom. The second structural layer is bonded and fixed to the open portion of the cavity. The second structural layer and the cavity form a sealed chamber, creating an electrical shield, eliminating capacitive coupling, and preventing electrostatic induction. This reduces the impact of the surrounding field strength on the overall performance of the structure, thereby improving the sensing accuracy of the vibration sensor of the present invention. The cavity wall is provided with a small hole to facilitate the extraction of the positive and negative wires.

[0006] The third structural layer is fixedly arranged on the side of the second structural layer close to the cavity using insulating glue. The insulating glue insulates the two, so that short circuit or carrier transfer does not occur when an electrical circuit is formed. Specifically, the third structural layer is a piezoelectric material. Preferably, the third structural layer is a piezoelectric ceramic PZT material. Due to the positive piezoelectric effect, under the action of an external force, the external force in the present invention refers to the deformation of the third structural layer, and an electric polarization effect is generated inside the piezoelectric material, so that the voltage thereon changes, which is detected by an external circuit. More specifically, the second structural layer and the third structural layer are fixedly connected to the negative electrode and the positive electrode respectively, so that the sensor of the present invention is connected to the external circuit.

[0007] The first structural layer is bonded and fixed to the side of the second structural layer away from the cavity. The first structural layer is a disc-shaped sound-conducting material, and the material of the first structural layer is 3M adhesive material. The first structural layer protects the second structural layer and prevents the second structural layer from oxidation, thereby reducing the electrical properties of the second structural layer. The first structural layer is bonded and fixed to the side away from the second structural layer with a rubber contact, specifically, it is bonded and connected using polyurethane glue. The material of the rubber contact is a sound-conducting material. Specifically, the shape of the rubber contact is cylindrical, and the material of the rubber contact is silicone. Silicone material has good softness and elasticity, good buffering performance, and good sound conductivity and wear resistance. The rubber contact can generate a larger amplitude, thereby making the deformation degree of the second structural layer and the third structural layer greater in turn, thereby having a higher detection sensitivity. The rubber contact and the first structural layer jointly receive the sound vibration to be measured.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] (1) The sensor of the present invention is composed of a colloid contact, a first structural layer, a second structural layer, a third structural layer, a cavity, and a shell. The second structural layer and the cavity form a closed chamber. The colloid contact, the first structural layer, the second structural layer, and the third structural layer are in close contact with each other in sequence to transmit the acoustic vibration to be measured. Since the loss of the acoustic vibration during the transmission process is small, the third structural layer of the piezoelectric material eventually produces a large deformation, that is, the amplitude of the piezoelectric material caused by the acoustic vibration is large. Due to the positive piezoelectric effect of the piezoelectric material, an electric polarization phenomenon is generated in the third structural layer, which causes the voltage signal of the third structural layer to change. The change in the voltage signal is detected by an external circuit. Therefore, the sensitivity of the sensor of the present invention is high.

[0010] (2) When the third structural layer vibrates, the air in the cavity expands or compresses accordingly, that is, the sound wave propagates in the cavity and is reflected multiple times on the cavity wall and superimposed multiple times on the third structural layer, which makes the deformation of the third structural layer greater, further enhancing the amplitude of the piezoelectric material caused by the acoustic vibration. For piezoelectric materials, due to the positive piezoelectric effect, a larger pressure change will make the electric polarization phenomenon of the third structural layer stronger, the potential difference on the surface of the third structural layer increases, and the change in the voltage signal detected by the external circuit is larger. Therefore, the sensitivity of the sensor of the present invention is higher.

[0011] (3) Since the colloid contact and the first structural layer receive acoustic vibrations together and there is coupling between the two, the resonant frequency of the structure of the present invention is relatively small, so the low-frequency response is better and there is more low-frequency information. The low-frequency information contains more acoustic vibration information, and more low-frequency information makes the detection accuracy higher.

[0012] (4) The flatness of the sensor within the response bandwidth of the present invention is better, and the detection signal is more stable, so the stability of the sensor of the present invention is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a front view of a highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0014] Figure 2 A three-dimensional diagram of a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0015] Figure 3 A schematic diagram (solid body) showing the separation of components of a highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0016] Figure 4 A schematic diagram (lines) illustrating the separation of components of a highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0017] Figure 5The relationship between the thickness of the colloidal contact (the height of the cylinder) and the resonant frequency of the sensor in a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0018] Figure 6 The resonant frequency simulation results of a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0019] Figure 7 The resonant frequency simulation results of a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention when the colloid contact is removed;

[0020] Figure 8 The harmonic response analysis curve of a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity provided by the present invention;

[0021] Figure 9 The harmonic response analysis curve of a high-sensitivity piezoelectric acoustic vibration sensor combining a single contact point and a cavity provided by the present invention when the colloid contact point is removed is provided.

[0022] Icon: 1-colloid contact; 2-first structural layer; 3-second structural layer; 4-third structural layer; 5-cavity; 6-shell. DETAILED DESCRIPTION

[0023] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0024] The present invention provides a high-sensitivity piezoelectric acoustic vibration sensor that combines a single contact with a cavity, such as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4As shown, the sensor comprises: a colloidal contact 1, a first structural layer 2, a second structural layer 3, a third structural layer 4, a cavity 5, and a housing 6. The cavity 5 is a cylindrical hollow cavity 5, the cavity wall of which is made of metallic copper. The top surface of the cylindrical cavity 5 is open to facilitate the placement of a second structural layer 3 of a shape and size matching the opening. The second structural layer 3 is in the shape of a flat cylinder, and its size matches the opening of the cavity 5, that is, the second structural layer 3 serves as a "lid" for the open cavity 5. The second structural layer 3 and the cavity 5 form a closed space. The thickness of the second structural layer 3 ranges from 0.1 to 0.2 mm. Practical testing has shown that this thickness range ensures that the second structural layer 3 is neither too thin to break nor too thick to deform too little, thereby reducing sensitivity. Therefore, the thickness of the second structural layer 3 is 0.1 to 0.2 mm, making it less prone to breakage and allowing for greater deformation, thereby making the sensor of the present invention more durable and more sensitive. Specifically, the plane of the second structural layer 3 close to the cavity 5 is not a plane, and the thickness near the edge is thinner. The plane of the thinner area is a concentric circle, and the radius difference of the concentric circle is less than the thickness of the cavity wall of the cavity 5, so that the middle area of ​​the second structural layer 3 is thicker, forming a convex shape toward the side of the cavity 5. Correspondingly, the cavity wall at the opening of the cavity 5 is not a plane either, and the height of the cavity wall near the inner side of the cavity 5 is less than the height of the edge, forming a half groove shape, which matches the convex shape of the second structural layer 3 close to the cavity 5. The contact points with the cavity 5 are fixed and bonded together by glue. Specifically, polyurethane glue is used, which can make the contact between the second structural layer 3 and the cavity 5 closer and firmer, forming a closed cavity 5; the material of the second structural layer 3 is copper, and the cavity 5 and the second structural layer 3, both of which are made of copper, form a closed space, thus forming a shielded cavity, connecting the ground wire of its internal circuit with the body lead to form an electrical shield, eliminating capacitive coupling, and preventing electrostatic induction, so as to reduce the influence of the field strength of the surrounding environment on the overall performance of the structure, thereby improving the sensing accuracy of the vibration sensor of the present invention; copper material is low in price, good in ductility, high in compressive strength and good in durability, and is stable and reliable in use and suitable for cavity walls. Thin metal copper is easy to deform and is suitable for the second structural layer 3. Secondly, copper material has good conductivity, which is convenient for setting electrodes on it. The cavity 5 has a small hole in the wall for lead-out wires. Specifically, the hole is located at the center height of the cavity wall. If it is located close to the second structural layer 3, it is too close to the third structural layer 4, which can easily damage the third structural layer 4 during operation. If it is located on the side of the cavity wall away from the second structural layer 3, that is, the hole is located far from the third structural layer 4, the wire distance is too long when the second structural layer 3 and the third structural layer 4 are used as positive and negative leads. Experimental testing has shown that the hole located at the center height of the cavity wall has little impact on the overall performance of the structure. The cavity wall thickness needs to be greater than 1.0 mm, specifically, it can be 1.1 mm.

[0025] The first structural layer 2 is fixedly provided on the side of the second structural layer 3 away from the cavity 5 , and the first structural layer 2 and the second structural layer 3 are bonded together by polyurethane glue. The material of the first structural layer 2 is 3M adhesive material, which has good sound conductivity and wear resistance. On the one hand, the contact area between the first structural layer 2 and the second structural layer 3 is large, and the first structural layer 2 has good sound conductivity, which can well transmit the acoustic vibration of the rubber particle contact 1 to the second structural layer 3, causing the second structural layer 3 to deform. At the same time, the first structural layer 2 is also exposed to the sound field to be measured, so that the sound field to be measured also causes the first structural layer 2 to vibrate accordingly, that is, the first structural layer 2 can receive the sound vibration alone, thereby making the deformation degree of the second structural layer 3 greater, thereby improving the sensitivity of the sensor. On the other hand, the wear resistance of the first structural layer 2 enables the first structural layer 2 to protect the second structural layer 3, so that the second structural layer 3 does not directly contact the air, thereby avoiding oxidation of the second structural layer 3. The oxidation of the second structural layer 3 will cause its material to change from metallic copper to copper oxide, and the conductivity, ductility and compressive resistance of the copper oxide material are not as good as metallic copper. Therefore, preventing the oxidation of the second structural layer 3 makes the sensor of the present invention more stable. The first structural layer 2 is shaped like an oblate cylinder. The height of the oblate cylinder, or the thickness of the first structural layer 2, can be 0.05 mm. Experimental testing has shown that the sensor of the present invention exhibits higher sensitivity when the first structural layer 2 is 0.05 mm thick. This is due to the good acoustic conductivity of the first structural layer 2 at this thickness. The first structural layer 2 was purchased. The rubber contact 1 is fixedly mounted on the side of the first structural layer 2 facing away from the second structural layer 3. The second structural layer 3 and the rubber contact 1 are bonded together with polyurethane glue. The end of the rubber contact 1 facing away from the first structural layer 2 is used to receive vibration signals.

[0026] The material of the rubber contact 1 is silicone, and the end face material of the rubber contact 1 close to the first structural layer 2 is 3M adhesive material, which can make the rubber contact 1 and the first structural layer 2 easily fixed together. At the same time, the contact parts between the rubber contact 1 and the first structural layer 2 are all 3M adhesive material, which makes it easier for the two to couple together during vibration, thereby reducing the resonant frequency; silicone material has good softness and elasticity, good buffering performance, and good sound conductivity and wear resistance. When the sound vibration to be measured remains unchanged, the rubber contact 1 can produce a larger amplitude, thereby making the deformation degree of the second structural layer 3 greater, thereby increasing the detection sensitivity.

[0027] The shape of the colloidal contact 1 is cylindrical. When the sensor of the present invention is used as a heart sound and electrocardiogram sensor, the cylindrical colloidal particles will be more comfortable in contact with the human body and the foreign body sensation will be reduced. The cylindrical colloidal contact 1 is an oblate cylindrical shape. Specifically, Figure 5It is shown that the relationship between the resonant frequency of the sensor and the height of the cylindrical colloid contact 1 is that the higher the height of the cylinder, the lower the resonant frequency. At the same time, the higher the height of the cylinder, the easier it is for the transmission of the acoustic vibration to be measured to be distorted and the energy loss is also greater. Therefore, the height of the cylinder is 4-6mm. When it is too high, the transmission distortion of the acoustic vibration is more serious and the energy loss is greater. When it is too low, the resonant frequency is higher and the low-frequency information cannot be detected. More specifically, the height of the cylinder can be 5mm. The bottom diameter of the cylindrical colloid contact 1 can be 15mm. In this way, the flat cylindrical colloid contact 1 has a larger contact area with the vibration signal to be measured and the first structural layer 2, which can make the deformation of the first structural layer 2 more uniform, and then make the deformation degree of the second structural layer 3 and the third structural layer 4 greater, so that the electrical characteristics of the third structural layer 4 change more and the sensitivity is higher. Moreover, the distance between the colloid contact 1 and the first structural layer 2 is relatively close, which reduces the distortion and energy loss of the acoustic vibration transmission caused by the long distance, thereby improving the accuracy of the sensor of the present invention. The cylindrical center axis of the colloid contact 1 passes through The geometric center of the first structural layer 2 is perpendicular to the plane of the first structural layer 2 close to the colloid contact 1. This allows the acoustic vibration to propagate through the colloid contact 1 and act on the third structural layer 4 at the point of maximum displacement, thereby generating a larger deformation. Due to the positive piezoelectric effect, the electrical characteristics of the third structural layer 4 change significantly, thereby causing a larger change in the detected electrical signal, that is, the sensitivity of the sensor of the present invention is higher. The number of colloid contacts 1 is one, and using one colloid contact 1 to receive acoustic vibrations can make the vibration deformation of the colloid contact 1 more concentrated at the point of maximum displacement in the center of the third structural layer 4, thereby increasing the sensitivity. The colloid contact 1 and the first structural layer 2 jointly receive the acoustic vibration to be measured, and the coupling between the two can reduce the resonant frequency of the sensor of the present invention, thereby containing more low-frequency acoustic vibrations. The effective information of the acoustic vibrations is at low frequency, therefore, the sensitivity of the sensor of the present invention is higher.

[0028] A third structural layer 4 is fixedly attached to the side of the second structural layer 3 near the cavity 5. The two are fixed together with an insulating adhesive. This allows the third structural layer 4 to deform with the deformation of the second structural layer 3, and the two are insulated. The third structural layer 4 is made of a piezoelectric material, specifically a piezoelectric ceramic PZT material. The third structural layer 4 is shaped like an oblate cylinder. The radius of the cylinder's base is slightly smaller than the radius of the raised surface of the second structural layer 3 near the cavity 5. The central axis of the oblate cylindrical third structural layer 4 is collinear with the central axis of the second structural layer 3. Specifically, the base diameter can be 15-20 mm. The change in electrical signal caused by the positive piezoelectric effect is related to both the area and degree of deformation of the piezoelectric material. The larger the area, the greater the change in the electrical properties of the piezoelectric material caused by the same degree of deformation. A gap is left for applying voltage to the second structural layer 3. This ensures a larger change in electrical signal caused by the positive piezoelectric effect, resulting in higher sensor sensitivity and convenient voltage setting. The thickness of the third structural layer 4, i.e., the height of the oblate cylinder, can be 0.2 mm. Test results show that this thickness sensor has the highest sensitivity. Due to the positive piezoelectric effect of the piezoelectric ceramic material, the deformation of the third structural layer 4 will cause electric polarization inside the structure, thereby converting mechanical energy into electrical energy, causing changes in the electrical signal in the external circuit, and realizing the sensing of acoustic vibration. On the surface of the second structural layer 3 on the side close to the cavity 5, the negative electrode is fixedly welded in the gap between the third structural layer 4 and the surface of the third structural layer 4 on the side close to the cavity 5. The positive and negative electrode wires are led out of the cavity 5 through the small holes on the side wall of the cavity 5 and connected to the external circuit. At the same time, in order to ensure the airtightness of the cavity 5, the size of the small hole is slightly larger than the sum of the diameters of the wires, and hot melt adhesive is used to seal the hole. Since the second structural layer 3 and the third structural layer 4 are fixed by insulating glue, there is no conduction between the two, and the positive and negative electrodes are connected to the external circuit to form a detection loop. Since piezoelectric materials are easily broken, the deformation of the second structural layer 3 causes the third structural layer 4 to deform, which can increase the force-bearing area of ​​the third structural layer 4, make the force uniform, reduce the pressure, and thus prevent the third structural layer 4 from breaking, thereby improving the safety of the sensor of the present invention; the deformation of the third structural layer 4, that is, the vibration of the third structural layer 4, will cause the air in the closed cavity 5 to expand and contract periodically with the vibration of the third structural layer 4, and multiple reflections and superpositions on the cavity wall will act on the third structural layer 4 again, making the deformation degree of the third structural layer 4 greater, thereby converting more mechanical energy into electrical energy, detecting a larger change in the electrical signal, and improving the sensitivity of the sensor of the present invention; at the same time, arranging the third structural layer 4 on the side of the second structural layer 3 close to the cavity 5 can reduce the volume of the sensor of the present invention, making the device conform to the trend of miniaturization.

[0029] Shell 6 is made of epoxy resin. Unsaturated polyester resin is lightweight, strong, chemically resistant, and electrically insulating, and its molding process is simple and easy. Therefore, choosing epoxy resin for shell 6 provides effective corrosion protection. Shell 6 has the same shape as cavity 5 and is slightly larger than cavity 5. Specifically, the outer surface of cavity 5 matches the inner surface of shell 6, with nearly identical dimensions. Polyurethane glue secures the connection between cavity 5 and shell 6 to ensure a tight seal. Shell 6 can be 0.8 mm thick, providing effective protection while maintaining a low weight for the sensor. Shell 6 has small holes in its walls that correspond to those in cavity 5.

[0030] During application, the wires drawn out from the third structural layer 4 are connected to the positive electrode, and the wires drawn out from the second structural layer 3 are connected to the negative electrode, and together with the power supply, they form an external circuit for detecting the voltage signal in the external circuit. Specifically, the external circuit also includes a filtering module, an amplifying module, a transmission module, etc. The configuration of these modules is only to better obtain the voltage change. The colloidal contact 1 and the first structural layer 2 are used to receive the acoustic vibration to be measured. Under the action of the acoustic vibration to be measured, the colloidal contact 1 causes the first structural layer 2 to vibrate and deform, and the second structural layer 3 vibrates along with the vibration of the first structural layer 2, thereby causing the third structural layer 4 to vibrate and deform. According to the positive piezoelectric effect, an electric polarization phenomenon is generated, and the potential difference on the surface of the third structural layer 4 changes. The voltage signal change is detected through the external circuit, and the vibration condition of the acoustic vibration to be measured is detected. The low loss and high conductivity characteristics of the colloid contact 1 and the large-area close connection between the colloid contact 1 and the first structural layer 2 and the second structural layer 3, and the fact that the first structural layer 2 and the second structural layer 3 are easy to deform, all make the third structural layer 4 deform more greatly; at the same time, when the third structural layer 4 vibrates, the air in the cavity 5 expands or compresses accordingly, that is, the sound wave propagates in the cavity 5, and at the same time is reflected multiple times on the cavity wall and superimposed multiple times on the third structural layer 4, making the third structural layer 4 deform more greatly; the deformation degree of the third structural layer 4 is greater, for piezoelectric materials, due to the positive piezoelectric effect, a larger pressure change will make the electric polarization phenomenon of the third structural layer 4 stronger, the potential difference on the surface of the third structural layer 4 increases, and the change in the voltage signal detected by the external circuit is larger, therefore, the sensitivity of the sensor of the present invention is higher.

[0031] At the same time, the vibrations of the colloid contact 1 and the first structural layer 2 are coupled to each other, especially at the contact point between the two. The small-area point vibration of the colloid contact 1 and the surface vibration of the first structural layer 2 are coupled to each other, making the resonant frequency of the structure of the present invention small. In this way, the low-frequency response is better, the low-frequency information is more, and the low-frequency information contains more acoustic vibration information. More low-frequency information makes the detection accuracy higher. Specifically, the simulation results obtained using COMSOL finite element simulation software show that the resonant frequency of the structure of the present invention is small. More specifically, Figure 6 and Figure 7 As shown, the resonant frequencies of the sensor of the present invention when the colloidal contact 1 is set and when the colloidal contact 1 is not set are 1192.5 Hz and 2024.5 Hz respectively. The former is lower than the latter. The resonant frequency corresponding to the sensor with the colloidal contact 1 is greatly reduced, so that lower frequency acoustic vibration can be obtained, and thus the sensitivity of the device of the present invention is higher. Figure 8 and Figure 9 The harmonic response analysis curves when setting the colloid contact 1 and not setting the colloid contact 1 are compared after setting the colloid contact 1. Figure 7 and Figure 8 It can be seen that the fluctuation is not very large within a certain range before reaching the inflection point, tends to be gentle, and the flatness is relatively high, that is, the flatness within the sensor response bandwidth is improved, and the detection signal is more stable. Therefore, the stability of the sensor of the present invention is better.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A highly sensitive piezoelectric acoustic vibration sensor combining a single contact and a cavity, characterized in that: The sensor includes a first structural layer, a second structural layer, a third structural layer, and a cavity. The cavity is shaped like a hollow cylinder lacking a bottom surface. The second structural layer is a disc-shaped metal material. The second structural layer is bonded and fixed to the open portion of the cavity. The second structural layer and the cavity form a closed chamber. The third structural layer is fixedly arranged on a side of the second structural layer close to the cavity. The third structural layer is a piezoelectric material. The first structural layer is bonded and fixed to a side of the second structural layer away from the cavity. A colloidal contact is fixedly provided on the side of the first structural layer away from the second structural layer, and the colloidal contact and the first structural layer jointly receive the sound vibration to be measured; the material of the colloidal contact is silicone, the material of the first structural layer is 3M adhesive material, the material of the second structural layer is metallic copper, and the material of the third structural layer is piezoelectric ceramic; the thickness of the planar center area of ​​the second structural layer close to the side of the cavity is greater than the thickness of the edge area.

2. The high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity according to claim 1, characterized in that: The radius of the second structural layer is the same as the radius of the bottom surface of the cavity.

3. The high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity according to claim 2, characterized in that: The second structural layer and the third structural layer are fixedly connected by insulating glue.

4. The high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity according to claim 3, characterized in that: Small holes are provided on the side walls of the cavity.

5. The high-sensitivity piezoelectric acoustic vibration sensor combining a single contact and a cavity according to claim 1, characterized in that: The material of the cavity wall is metallic copper.

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