A multi-well arrayed PZT based acoustic vibration cavity sensing structure

Abstract

The application relates to the technical field of sound wave detection, in particular to a sound vibration cavity sensing structure based on a porous array type PZT, which comprises a cavity, a piezoelectric ceramic film, a positive electrode and a negative electrode. The piezoelectric ceramic film is arranged on the opening of the cavity and is fixedly connected with the opening end of the cavity. A plurality of half-through holes are arranged on the piezoelectric ceramic film. The positive electrode is arranged on the outer surface of the piezoelectric ceramic film, and the negative electrode is arranged on the inner surface of the piezoelectric ceramic film. The material of the piezoelectric ceramic film is lead zirconate titanate. The application has higher sensitivity and better low-frequency response performance, and has a good application prospect in the technical field of sound wave detection.

Description

Technical Field

[0001] This invention relates to the field of acoustic wave detection technology, and specifically to an acoustic vibration cavity sensing structure based on a multi-hole array PZT. Background Technology

[0002] The coal mining industry is a highly dangerous industry operating in a complex environment, making safety paramount. Besides gas-related accidents, mine vibrations are another source of accidents. Furthermore, detecting even subtle vibrations is an important method for studying coal mine disasters; by analyzing vibration signals, mine disasters can be effectively predicted.

[0003] Acoustic vibration sensors convert sound wave signals into electrical signals, enabling acoustic vibration sensing. Typically, an acoustic vibration sensor consists of a sensing element and a transducer. Current acoustic vibration sensors mainly include microphone sensors, piezoresistive sensors, and piezoelectric sensors. Capacitive microphone sensors are easy to use and relatively inexpensive, widely used in the medical field; however, they are susceptible to environmental noise, leading to a reduced signal-to-noise ratio, making them unsuitable for acoustic vibration sensing in the coal mining industry. Piezoresistive sensors are also widely used, especially MEMS piezoresistive sensors, but their high manufacturing cost makes them unsuitable for mass production, and their poor stability and susceptibility to damage also hinder their application in coal mining. Piezoelectric sensors offer high sensitivity and small size, often used in wearable detection, such as monitoring weak physiological signals like pulse and heart sounds. Furthermore, piezoelectric sensors easily detect weak acoustic vibrations, making them promising for applications in the coal mining industry. However, the sensitivity of existing piezoelectric sensors remains relatively low and cannot meet the requirements for monitoring weak vibrations in the coal mining industry. Summary of the Invention

[0004] To address the above problems, this invention provides an acoustic vibration cavity sensing structure based on a porous array PZT, comprising a cavity, a piezoelectric ceramic film, a positive electrode, and a negative electrode. The piezoelectric ceramic film is disposed on the opening of the cavity and is fixedly connected to the opening end of the cavity. The piezoelectric ceramic film has multiple semi-through holes. The positive electrode is disposed on the outer surface of the piezoelectric ceramic film, and the negative electrode is disposed on the inner surface of the piezoelectric ceramic film. The material of the piezoelectric ceramic film is lead zirconate titanate.

[0005] Based on the traditional ferroelectric material lead zirconate titanate (PZT), this invention proposes a porous array PZT sensor, which is combined with an acoustic resonant cavity to improve the sensitivity and low-frequency response performance of the piezoelectric sensor. This structure features high sensitivity, fast response speed, and strong anti-interference ability, and can be used in fields such as acoustic sensors and biosensors.

[0006] Furthermore, the cavity is cylindrical, the piezoelectric ceramic film is disc-shaped, and there are 21 semi-through holes. The semi-through holes are distributed on the piezoelectric ceramic film with a square spacing. The semi-through holes are divided into 5 columns, with 3, 5, 5, 5, and 3 semi-through holes in each column. The semi-through hole in the center of the third column is located at the center of the piezoelectric ceramic film.

[0007] Furthermore, the inner diameter of the cavity is 1.2 cm, the radius of the semi-through hole is 0.2 cm, the thickness of the semi-through hole is 0.19 cm, the distance between the semi-through holes is 0.45 cm, the thickness of the piezoelectric ceramic film is 0.23 cm, and the depth of the cavity is 0.7 cm.

[0008] Furthermore, the cavity is made of copper.

[0009] Furthermore, it also includes an elastomer protective film, which is placed on a piezoelectric ceramic film.

[0010] Furthermore, the elastomer protective film is adhered to the surface of the piezoelectric ceramic film using AB adhesive.

[0011] Furthermore, the material of the elastomer protective film is polyurethane.

[0012] Furthermore, the piezoelectric ceramic film is connected to the sidewall of the cavity by adhesive bonding or hot pressing.

[0013] Furthermore, the materials for the positive and negative electrodes are thin metal films or conductive polymers.

[0014] Furthermore, acoustic vibration cavity sensing structures are used for biosensing, in which the biomolecules to be measured are placed on an elastomer protective membrane.

[0015] The beneficial effects of this invention are:

[0016] (1) Traditional piezoelectric sensors use piezoelectric ceramic materials as the sensing element. The present invention proposes a novel porous array PZT acoustic vibration cavity sensing structure. Compared with the traditional PZT thin film structure, the present invention has higher sensitivity and better low-frequency response performance.

[0017] (2) The present invention designs a cavity structure, and further improves the sensor sensitivity by designing an acoustic resonant cavity.

[0018] In summary, this invention has promising application prospects in the field of acoustic wave detection technology.

[0019] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an acoustic vibration cavity sensing structure based on a porous array PZT.

[0021] Figure 2 This is a schematic diagram of a piezoelectric ceramic thin film.

[0022] Figure 3 It represents the stress magnitude on the piezoelectric ceramic thin film under different structural parameters.

[0023] Figure 4 The stress distribution comparison diagrams are as follows: (a) the structure of the present invention, and (b) the ordinary PZT structure.

[0024] Figure 5 This is a displacement comparison between the porous array PZT acoustic vibration cavity sensing structure of the present invention and the ordinary PZT acoustic vibration sensing structure.

[0025] Figure 6 The diagram shows a comparison of the natural frequencies of the porous array PZT acoustic vibration cavity sensing structure of the present invention and the ordinary PZT acoustic vibration sensing structure: (a) the structure of the present invention, (b) the ordinary PZT structure.

[0026] Figure 7 This paper compares the frequency domain response characteristics of the porous array PZT acoustic vibration cavity sensing structure of the present invention with those of the ordinary PZT acoustic vibration sensing structure.

[0027] Figure 8 This is a comparison of the potential distribution between the porous array PZT acoustic vibration cavity sensing structure of the present invention and the ordinary PZT acoustic vibration sensing structure.

[0028] Figure 9 This is a comparison of the surface voltage output of the porous array PZT acoustic vibration cavity sensing structure of the present invention with that of a conventional PZT acoustic vibration sensing structure.

[0029] In the figure: 1. Cavity; 2. Piezoelectric ceramic film; 21. Semi-through hole. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0031] This invention provides an acoustic vibration cavity sensing structure based on a porous array PZT. For example... Figure 1As shown, the acoustic vibration cavity sensing structure includes a cavity, a piezoelectric ceramic film, a positive electrode, and a negative electrode (the positive and negative electrodes are not shown in the figure). The cavity is made of copper and is cylindrical, including a bottom and sides. The piezoelectric ceramic film is made of lead zirconate titanate (PZT) and is disk-shaped. The piezoelectric ceramic film is disposed on the opening of the cavity and is fixedly connected to the opening end of the cavity. The piezoelectric ceramic film has multiple semi-through holes, with the semi-through holes formed on the side of the piezoelectric ceramic film away from the cavity. Specifically, as shown... Figure 2 As shown, there are 21 semi-through holes spaced at square intervals on the piezoelectric ceramic film. The semi-through holes are arranged in 5 columns, with each column containing 3, 5, 5, 5, and 3 semi-through holes. The central semi-through hole in the third column is located at the center of the piezoelectric ceramic film. The positive electrode is disposed on the outer surface of the piezoelectric ceramic film, and the negative electrode is disposed on the inner surface. During the fabrication of the PZT film, polarization is required to achieve its piezoelectric properties. By placing the positive electrode on the outer surface and the negative electrode on the inner surface, it is ensured that the electric field direction is consistent with the film's polarization direction when an electric field is applied, thereby maximizing the piezoelectric effect of the PZT material. Furthermore, placing the positive electrode on the outer surface facilitates signal contact and connection for integration with external circuits or devices, simplifying circuit design and improving signal transmission reliability. Placing the negative electrode on the inner surface helps to uniformly distribute the electric field, avoiding uneven distribution or leakage within the material. The materials of the positive and negative electrodes are metal thin films or conductive polymers.

[0032] On the one hand, this invention introduces semi-through holes into the traditional piezoelectric ceramic film, increasing the effective sensing area of ​​the sensor and the path of sound wave transmission, enabling the sensor to receive more acoustic vibration energy, and the sound waves can be transmitted more effectively into the PZT material, improving the sensor's sensitivity, and allowing the piezoelectric ceramic film to sense weaker acoustic vibrations; on the other hand, this invention sets up a cavity structure below the piezoelectric ceramic film, forming a sound wave reflection or resonant cavity effect. Both of these effects result in the acoustic vibration cavity sensing structure based on porous array PZT proposed in this invention having higher acoustic detection sensitivity. In addition, this invention also has other beneficial effects: (1) Since the porous structure increases the effective surface area of ​​the sensor, it enhances the force of sound waves on the PZT piezoelectric material, thereby enhancing the piezoelectric effect and obtaining a higher output signal. Secondly, by designing the size, shape and distribution of the semi-through holes, the structural stiffness is adjusted, the natural frequency of the sensor is reduced, and better low-frequency response performance is achieved. This invention has good low-frequency response performance. (2) Since the multi-hole array structure has a low mass, the structure itself has a small inertia under the action of external acoustic vibration, and the response speed to vibration is faster. Secondly, when the acoustic signal acts on the PZT, the vibration can be transmitted to the PZT interior faster and more effectively through the semi-through holes, which improves the response speed of the sensing structure. This invention has the advantage of fast response speed. (3) Due to the design of the multi-hole array, the acoustic wave filtering effect in a specific frequency range can be realized, thereby reducing the response to interference signals. This invention has the advantage of strong anti-interference ability.

[0033] To verify the effectiveness of the technical solution of this invention, the applicant used COMSOL finite element simulation software to simulate the acoustic sensing characteristics of the proposed structure. In the simulation, the arrangement of the semi-through holes was as follows: Figure 2 As shown. In the calculation, the Young's modulus of the piezoelectric ceramic thin film is 63 × 10⁻⁶. 9 Pa, the distance between the semi-through holes is fixed at 0.45 cm, the depth of the cavity is fixed at 0.7 cm, the thickness of the bottom surface of the cavity is 0.3 cm, and the thickness of the side surface of the cavity is 0.05 cm. The applicant calculated the stress magnitude of the proposed structure for different semi-through hole radii (r1), different semi-through hole heights (h1), and different cavity radii (r2), such as... Figure 3 As shown, the maximum stress of the sensing structure increases with the increase of parameters r1, h1, and r2. From Figure 3 The optimal solution of the proposed structure can be obtained. Under the condition of maximizing the stress of the sensing structure, considering the rationality between the structural parts and the whole, the parameters are finally determined as follows: the radius of the semi-through hole is 0.2 cm, the thickness of the semi-through hole is 2.3 cm, and the inner diameter of the cavity is 1.2 cm.

[0034] Figure 4A comparison of stress distribution between the porous array PZT acoustic sensing structure of this invention and a conventional PZT acoustic sensing structure is presented. A conventional PZT acoustic sensing structure refers to a piezoelectric ceramic thin film without any semi-through holes. From... Figure 4 As can be seen, under the same pressure, the maximum stress value of the porous array sensing structure is greater than that of the ordinary PZT sensing structure, specifically, at 1 N / m. 2 Under the action of the multi-hole array sensing structure, the maximum stress is 234 N / m. 2 The maximum stress in a typical PZT sensor structure is 22.9 N / m. 2 The maximum stress of the porous array PZT acoustic sensing structure of the present invention is 10 times that of the ordinary PZT structure.

[0035] Figure 5 A displacement comparison between the porous array PZT acoustic sensing structure of this invention and a conventional PZT acoustic sensing structure is presented. A conventional PZT acoustic sensing structure refers to a piezoelectric ceramic thin film without through holes. From... Figure 5 It can be seen that the maximum displacement of both structures occurs at an arc length of 1.3 cm, while the maximum displacement of the porous array structure is 4.59 × 10⁻⁶. -9 The maximum displacement of a typical PZT sensing structure is 5.79 × 10⁻⁶. -10 The maximum displacement of the piezoelectric ceramic thin film in the porous array PZT acoustic sensing structure of the present invention is an order of magnitude higher than that of the ordinary PZT structure.

[0036] Figure 6 The natural frequency mode shapes of the porous array PZT acoustic sensing structure of this invention and the ordinary PZT acoustic sensing structure are shown. As can be seen from the figures, the first natural frequency of the porous array PZT sensing structure is 14961 Hz, while the first natural frequency of the ordinary PZT sensing structure is 19825 Hz. The natural frequency of the porous array PZT acoustic sensing structure of this invention is lower than that of the ordinary PZT structure, which is beneficial for better sensing and response to low-frequency acoustic vibration signals.

[0037] Figure 7 A comparison of the frequency domain response characteristics of the porous array PZT acoustic sensing structure of this invention and the ordinary PZT acoustic sensing structure is presented. As can be seen from the figure, the resonant frequency of the porous array PZT sensing structure is at 15000Hz, at which point the sensor displacement is 4.574 × 10⁻⁶. -7 cm, the resonant point of a typical PZT sensor structure is at 20000Hz, at which point the sensor displacement is 2.651 × 10 cm. -9 cm, the resonance points of both structures are at the same level. Figure 6The inherent frequency points shown are basically the same. At this frequency, the sensor resonates. Compared with the ordinary PZT structure, the multi-hole array PZT acoustic sensing structure of the present invention has better low-frequency response, which is beneficial for the detection of weak low-frequency signals.

[0038] Figure 8 A comparison of the potential distribution of the porous array PZT acoustic sensing structure of this invention and the ordinary PZT acoustic sensing structure is presented. As can be seen from the figure, the potential difference of the porous array PZT sensing structure is 5.028 × 10⁻⁶. -4 V, the potential difference of a typical PZT sensing structure is 2.536 × 10⁻⁶. -4 V, and both sensing structures generate the maximum potential at the center of the PZT film. Compared with the ordinary PZT structure, the porous PZT acoustic sensing structure of the present invention can generate a larger potential difference between the upper and lower surfaces, which is beneficial to increase the amplitude of the electrical signal and increase the sensitivity of the sensor. The larger potential difference allows the sensor to better capture and measure weak acoustic vibration signals.

[0039] Figure 9 A voltage comparison between the porous array PZT acoustic sensing structure of this invention and a conventional PZT acoustic sensing structure is presented. The figure shows that both sensing structures generate the maximum output voltage at the center of the PZT film, with the porous array PZT sensing structure exhibiting a maximum voltage of 3.213 × 10⁻⁶. -4 V, the maximum voltage value of a typical PZT sensing structure is 1.512 × 10⁻⁶. -4 V. The surface voltage output of the porous array PZT structure of the present invention is greater than that of the ordinary PZT structure, which is beneficial to enhance the overall output signal strength of the sensing structure.

[0040] As can be seen from the above structure, the porous array PZT acoustic sensing structure of the present invention improves both sensitivity and output voltage.

[0041] Furthermore, the acoustic vibration cavity sensing structure based on porous array PZT of the present invention also includes an elastomer protective film, which is placed on a piezoelectric ceramic film and is made of polyurethane. In addition to protecting the PZT film, the polyurethane elastomer first receives the vibration when it is generated. Through the action of sound waves, the PZT film generates a positive piezoelectric effect, converting mechanical energy into electrical energy, thereby generating an electrical signal. In this conversion process, the mechanical energy signal is directly converted into an electrical signal. Simultaneously, due to the rapid response of PZT material, the porous array PZT sensing structure can respond in real time when the vibration signal is applied, which is beneficial for real-time monitoring and control of the sensor.

[0042] Specifically, the elastomer protective film is adhered to the surface of the piezoelectric ceramic film using AB adhesive. The piezoelectric ceramic film is connected to the sidewall of the cavity by bonding or hot pressing. Preferably, the piezoelectric ceramic film is connected to the sidewall of the cavity by epoxy resin adhesive, which is convenient and quick to operate. During preparation, the porous array PZT film is prepared by etching and then transferred to the cavity. The porous structure helps to improve the sensitivity and response speed of the film.

[0043] Furthermore, the negative electrode is annular, with a size equal to the thickness of the sidewall of the vibration cavity, i.e., the radius of the annulus is 0.05 cm; the positive electrode is circular, with a size equal to the PZT film, i.e., the radius is 1.3 cm. This facilitates the connection between the positive electrode and the polyurethane elastomer, and between the negative electrode and the vibration cavity.

[0044] Furthermore, the negative electrode is positioned between the piezoelectric ceramic film and the side of the cavity; that is, the piezoelectric ceramic film is connected to the negative electrode, and the negative electrode is in turn connected to the side of the cavity. This reduces the mass of the piezoelectric ceramic film, improving the response speed of the sensing structure; on the other hand, it also enhances the stability of the structure.

[0045] Furthermore, the thickness of the piezoelectric ceramic film is non-uniform: the thickness is thicker at the center and thinner at the edges. This is beneficial for enhancing the piezoelectric effect of the PZT piezoelectric ceramic film, thereby improving the sensitivity and signal output of the sensing structure.

[0046] In addition, the present invention also discloses the application of the proposed acoustic vibration cavity sensing structure based on porous array PZT, that is, the acoustic vibration cavity sensing structure of the present invention is used for biosensing, and in application, the biomolecule to be measured is placed on the elastomer protective film.

[0047] In summary, this invention provides an acoustic vibration cavity sensing structure based on a porous array PZT, comprising a cavity, a piezoelectric ceramic thin film, a positive electrode, and a negative electrode. The piezoelectric ceramic thin film is disposed on the opening of the cavity and is fixedly connected to the opening end of the cavity. The piezoelectric ceramic thin film has multiple semi-through holes. The positive electrode is disposed on the outer surface of the piezoelectric ceramic thin film, and the negative electrode is disposed on the inner surface of the piezoelectric ceramic thin film. The material of the piezoelectric ceramic thin film is lead zirconate titanate. By introducing semi-through holes and setting up a cavity on the piezoelectric ceramic thin film, not only is the sensitivity of acoustic vibration detection improved, but it also exhibits good low-frequency response characteristics, showing promising application prospects in the field of acoustic wave detection technology.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A multi-porous array PZT-based acoustic vibration cavity sensing structure, comprising a cavity, a piezoelectric ceramic film, a positive electrode, and a negative electrode, wherein the piezoelectric ceramic film is arranged on an opening of the cavity, and the piezoelectric ceramic film is fixedly connected with an opening end of the cavity, characterized in that: The piezoelectric ceramic film is provided with a plurality of half-holes, the positive electrode is arranged on the outer surface of the piezoelectric ceramic film, the negative electrode is arranged on the inner surface of the piezoelectric ceramic film, and the material of the piezoelectric ceramic film is lead zirconate titanate. ​ 2. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 1, wherein: The cavity is cylindrical, the piezoelectric ceramic film is disc-shaped, the number of the half-holes is 21, the half-holes are distributed on the piezoelectric ceramic film with square spacing, the half-holes are divided into five columns, the number of the half-holes in each column is 3, 5, 5, 5 and 3, and the half-hole in the center of the third column is located at the center of the piezoelectric ceramic film.

3. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 2, wherein: The inner diameter of the cavity is 1.2 cm, the radius of the half-hole is 0.2 cm, the thickness of the half-hole is 0.19 cm, the distance between adjacent half-holes is 0.45 cm, the thickness of the piezoelectric ceramic film is 0.23 cm, and the depth of the cavity is 0.7 cm.

4. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 3, wherein: The material of the cavity is copper.

5. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 1, wherein: An elastomer protective film is further included and arranged on the piezoelectric ceramic film.

6. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 5, wherein: The elastomer protective film is adhered to the surface of the piezoelectric ceramic film by AB glue.

7. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 6, wherein: The material of the elastomer protective film is polyurethane material.

8. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 1, wherein: The piezoelectric ceramic film and the side wall of the cavity are connected by adhesion or hot pressing.

9. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 1, wherein: The material of the positive electrode and the negative electrode is metal film or conductive polymer.

10. The multi-well array PZT-based acoustic vibration cavity sensing structure of claim 7, wherein: The acoustic vibration cavity sensing structure is used for biological sensing, and when applied, the biological molecules to be measured are arranged on the elastomer protective film.

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