Sensitive element, preparation method thereof and application of sensitive element in preparation of high-sensitivity underwater acoustic receiving transducer

Abstract

The invention belongs to the technical field of underwater acoustic transducer piezoelectric materials, and particularly relates to a sensitive element, a preparation method thereof and application of the sensitive element in preparation of a high-sensitivity underwater acoustic receiving transducer, the sensitive element comprises a polymer phase material layer and further comprises a piezoelectric small column array module, and the polymer phase material layer is used for fixing the piezoelectric small column array module; the piezoelectric small column array module is composed of a plurality of piezoelectric small columns, the piezoelectric small columns are sequentially and electrically connected in series through electric leads, and the piezoelectric small columns connected with the first electric lead and the last electric lead are electrically connected with a positive electrode lead and a negative electrode lead respectively. Every two adjacent piezoelectric small columns are electrically connected in series, so that the high-receiving-sensitivity sensitive element applied to the underwater acoustic transducer is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric materials for underwater acoustic transducers, and relates to a sensitive element, a preparation method thereof, and an application thereof in the preparation of a high-sensitivity underwater acoustic receiving transducer. Background Art

[0002] Technologies such as underwater acoustic detection and anti-detection play an important role in maritime military and ocean development. Sound waves are the only known carriers that can transmit information and energy over long distances in the ocean. The underwater acoustic transducer, known as the "ears and eyes of underwater acoustic equipment", is a key part of sonar. With the development of detection technologies, especially the installation of sound insulation tiles on most submarines, submarines are integrated with ocean noise, which poses high-sensitivity requirements for sonar detection systems. Therefore, the development of high-sensitivity underwater acoustic transducers is of great significance.

[0003] The sensitivity of an underwater acoustic transducer reflects its ability to convert sound pressure into output voltage. Improving the sensitivity of an underwater acoustic transducer means improving its electromechanical conversion efficiency, and the electromechanical conversion efficiency reflects the quality of the underwater acoustic transducer in radiating and receiving sound waves. The electromechanical conversion efficiency is proportional to the electromechanical coupling coefficient. Therefore, improving the sensitivity of the transducer is to improve the electromechanical coupling coefficient of the transducer. Since the electromechanical coupling coefficient k of the length expansion and contraction vibration mode of the piezoelectric material 33 is usually greater than the electromechanical coupling coefficient k of the thickness vibration mode t , if the thickness vibration mode of the piezoelectric material is changed to the length expansion and contraction vibration mode, the electromechanical coupling coefficient of the piezoelectric material will be significantly improved. That is, by cutting a whole piece of pure piezoelectric ceramic into a piezoelectric ceramic column array structure, the thickness vibration mode of the pure piezoelectric ceramic is changed to the length expansion and contraction vibration of the piezoelectric ceramic column array, thereby improving the electromechanical coupling coefficient.

[0004] The prior art discloses 1-3 type piezoelectric composites and 1-3-2 type piezoelectric composites, which achieve the conversion of the thickness vibration mode of pure piezoelectric ceramic into the length expansion and contraction vibration of the piezoelectric ceramic column array, and the electromechanical coupling coefficient is increased by about 20%. However, when applied to an underwater acoustic receiving transducer, since the piezoelectric small columns of the 1-3 type piezoelectric composite and the 1-3-2 type piezoelectric composite are all connected in parallel, the sensitivity in the application of the underwater acoustic receiving transducer cannot meet the required requirements. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the present invention provides a sensitive element, a preparation method thereof, and an application thereof in the preparation of a high-sensitivity underwater acoustic receiving transducer. The present invention electrically connects every two adjacent piezoelectric small columns in series to obtain a sensitive element with high receiving sensitivity for application in an underwater acoustic transducer.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A sensitive element includes a polymer phase material layer and a piezoelectric small pillar array module. The polymer phase material layer is used to fix the piezoelectric small pillar array module. The polymer phase material layer in the prior art is completely filled in the piezoelectric small pillar array module, while in the present invention, the polymer phase material layer is used to cover both ends of the piezoelectric small pillar array module respectively.

[0008] The piezoelectric column array module is composed of a plurality of piezoelectric columns, and the plurality of piezoelectric columns are electrically connected in series in sequence through conductive wires, and the piezoelectric columns connected by the first and last conductive wires are electrically connected to the positive electrode lead and the negative electrode lead, respectively, that is, the positive electrode and the negative electrode of each piezoelectric column are respectively led out with conductive wires, and the positive electrode lead and the negative electrode lead are convenient for being electrically connected to other conductive elements. Compared with the prior art in which the upper end surface electrode is uniformly connected to the positive electrode and the lower end surface electrode is uniformly connected to the negative electrode, the present invention connects a plurality of piezoelectric columns in series, and they vibrate together, and the converted voltage signal is multiplied, thereby multiplying the receiving sensitivity of the underwater acoustic transducer;

[0009] To solve the problem of low receiving sensitivity, the present invention starts from two angles. The main angle is to connect the piezoelectric columns in series, and the secondary angle is to improve the filling of the polymer so that the polymer phase material layer covers the two ends of the piezoelectric column array module respectively, and then forms a hollow structure, so that the sensitive element changes from thickness vibration to length vibration.

[0010] Preferably, the height of each piezoelectric column is greater than its width to achieve length vibration of the sensitive element, and the height of the piezoelectric column is approximately 3-5 times its width. Under optimal conditions, the height and width of each piezoelectric column are consistent.

[0011] Preferably, the upper surface of each piezoelectric column is plated with a positive electrode and the lower surface is plated with a negative electrode. The two ends of the conductive wire are respectively electrically connected to the positive electrode and the negative electrode of two adjacent piezoelectric columns. The positive electrode lead is electrically connected to the positive electrode, and the negative electrode lead is electrically connected to the negative electrode. Based on the technical core of the present invention, the present invention provides a specific electrical connection method.

[0012] Preferably, the polymer phase material layers are symmetrically arranged, and the piezoelectric pillar array module is located between two polymer phase material layers. The position of the piezoelectric pillar array module is fixed by using two symmetrically arranged polymer phase material layers.

[0013] Preferably, the two polymer phase material layers and the piezoelectric pillar array module as a whole form a hollow structure, so that the gap between every two adjacent piezoelectric pillars is filled with air.

[0014] Preferably, the piezoelectric post is made of piezoelectric ceramics or piezoelectric single crystals, and the cross-section of the piezoelectric post is square, rectangular or circular. The shape of the piezoelectric post has no effect on the sensing element.

[0015] Preferably, the polymer phase material layer is an epoxy resin layer, a silicone rubber layer or a polyurethane layer. The polymer layer mainly serves to protect the electrodes and is a passive material.

[0016] The present invention also protects a method for preparing a sensing element, which includes the following steps:

[0017] A positive electrode and a negative electrode are respectively plated on the upper surface and the lower surface of the piezoelectric material, and the piezoelectric material is polarized along the Z-axis direction to obtain a polarized piezoelectric material; the polarization method is usually electric field polarization, and the purpose of polarization is to endow the piezoelectric material with piezoelectric effect and display polarity;

[0018] The polarized piezoelectric material is cut along the X-axis and Y-axis directions, and the cutting depth is less than the thickness of the polarized piezoelectric material, to obtain a piezoelectric post array module with a substrate. The substrate mainly keeps the positions of the piezoelectric posts stable after cutting;

[0019] A conductive wire is led out from the positive electrode of each piezoelectric post array module with a substrate to obtain a processed material I;

[0020] One end of the processed material I containing the positive electrode is immersed in the liquid polymer phase material, and after the liquid polymer phase material is cured, it is taken out to obtain a processed material II;

[0021] The substrate of the processed material II is cut through along the X-axis and Y-axis directions by a cutting machine, and at this time, a number of piezoelectric posts are obtained to obtain a piezoelectric post array module;

[0022] The free ends of the conductive wires on each piezoelectric post of the piezoelectric post array module are respectively taken out and electrically connected to the negative electrodes of the adjacent piezoelectric posts to obtain a processed material III;

[0023] The positive electrode lead and the negative electrode lead are respectively electrically connected to the first and the last piezoelectric posts to obtain a processed material IV;

[0024] One end of the processed material IV containing the negative electrode is immersed in the liquid polymer phase material, and after the liquid polymer phase material is cured, it is taken out to obtain a sensing element.

[0025] The present invention also protects the application of the sensing element in the preparation of a high-sensitivity underwater acoustic receiving transducer.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. In the prior art, for 1-3 type piezoelectric composites and 1-3-2 type piezoelectric composites, the upper surface electrodes are uniformly connected to the positive electrode, and the lower surface electrodes are uniformly connected to the negative electrode. Considering the deficiencies in the receiving sensitivity of 1-3 type piezoelectric composites and 1-3-2 type piezoelectric composites when applied in underwater acoustic receiving transducers, in the present invention, all piezoelectric small columns are connected in series with each other, changing the electrode connection method of traditional composites, and increasing the voltage by adopting a series connection method. Because after the receiving transducer senses the acoustic signal, acoustic-electric conversion will occur. When multiple piezoelectric small columns are connected in series and vibrate together, the converted voltage signal is increased by several times, thereby increasing the receiving sensitivity of the underwater acoustic transducer by several times.

[0028] 2. The present invention also takes into account the technical defects of 1-3 type piezoelectric composites and 1-3-2 type piezoelectric composites in the prior art due to the introduction of polymers, that is, the transverse vibration caused by the presence of polymers, which makes the mode impure. In the present invention, the gaps between piezoelectric small columns are not filled with polymers, effectively avoiding the transverse coupling between piezoelectric small columns, and improving the vibration mode purity of piezoelectric materials, and reducing the losses brought by polymers in traditional composites.

[0029] 3. Compared with the sensitive elements of underwater acoustic transducers in the prior art, the difference in the present invention is that the length expansion and contraction vibration in the present invention is a complete length expansion and contraction vibration, while the piezoelectric composite material of the sensitive element in the background technology strictly speaking still belongs to thickness vibration, which is only a technical improvement of the initial sensitive element;

[0030] In the present invention, the performance will not deteriorate after not filling the polymer. The reasons are as follows: a. Not filling the polymer avoids the losses brought by the polymer; b. Avoiding the transverse coupling between piezoelectric small columns highlights the longitudinal length expansion and contraction vibration of piezoelectric small columns. If the gaps between piezoelectric small column arrays are filled with polymers, the vibration behavior will be thickness vibration, and the electromechanical coupling coefficient of thickness vibration is less than that of longitudinal length expansion and contraction vibration.

[0031] 4. The present invention converts the thickness vibration of a whole piece of pure piezoelectric material into the length expansion and contraction vibration of a piezoelectric small column array, changes the vibration mode of the material, improves the electromechanical coupling coefficient, and thus improves the sensitivity of the transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of an embodiment of the sensitive element of the high-sensitivity underwater acoustic receiving transducer of the present invention;

[0033] Figure 2 It is the electrode connection method of the sensitive element of Embodiment 1 of the present invention;

[0034] Figure 3 It is a schematic structural diagram of the sensitive elements of Embodiment 1, Comparative Example 1, and Comparative Example 2 of the present invention;

[0035] Figure 4 Frequency admittance curve of a single piezoelectric stud of Comparative Example 1 of the present invention;

[0036] Figure 5 Receiving sensitivity curve of a single piezoelectric stud of Comparative Example 1 of the present invention;

[0037] Figure 6 Frequency admittance curve of two piezoelectric studs connected in series in Example 1 of the present invention;

[0038] Figure 7 Receiving sensitivity curve of two piezoelectric studs connected in series in Example 1 of the present invention;

[0039] Figure 8 Frequency admittance curve of two electric columns connected in parallel in Comparative Example 2 of the present invention;

[0040] Figure 9 Receiving sensitivity curve of two piezoelectric studs connected in parallel in Comparative Example 2 of the present invention;

[0041] Figure 10 Basic process of finite element simulation of an underwater acoustic receiving transducer.

[0042] Explanation of reference numerals

[0043] 1. Polymer phase material layer; 2. Piezoelectric stud array module; 21. Positive electrode lead; 22. Negative electrode lead; 23. Conductive wire; 24. Piezoelectric stud. Detailed description of the specific implementation mode

[0044] The following is a detailed description of the specific implementation mode of the present invention. However, it should be understood that the protection scope of the present invention is not limited by the specific implementation mode. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0045] In the 1-3 type piezoelectric composite material and the 1-3-2 type piezoelectric composite material of the prior art, the polymer completely fills the space between every two adjacent piezoelectric pillars. At this time, the existing technical defects are as follows: (a) increasing energy loss and reducing the electromechanical coupling coefficient; (b) increasing the lateral coupling between piezoelectric pillars, which is not conducive to the simplification of vibration modes, resulting in a reduction of the effective electromechanical coupling coefficient; (c) the addition of lossy polymers causes the device to heat up easily. Especially when the transducer works continuously, due to heating, the sensitive components will deform, resulting in great changes in the performance of the transducer and even damage. Considering the defects of the 1-3 type piezoelectric composite material and the 1-3-2 type piezoelectric composite material of the prior art, the present invention uses two symmetric polymer phase material layers to cover the two ends of the piezoelectric pillar array module respectively, forming a hollow structure to reduce energy loss, reduce lateral coupling, and effectively solve the problem of device heating.

[0046] In addition, the present invention changes the electrode connection method of the traditional composite material, achieving the purpose of doubling the receiving sensitivity of the underwater acoustic transducer.

[0047] The following is the specific preparation method of the sensitive component of the high-sensitivity underwater acoustic receiving transducer, and the steps are as follows:

[0048] Step 1: Select a piezoelectric material and polarize it in the Z-axis direction (perpendicular to the piezoelectric material sheet). The upper surface of the piezoelectric material is plated with a positive electrode, and the lower surface is plated with a negative electrode. Cut the piezoelectric material along the X-axis and Y-axis directions, and the cutting depth should be less than the thickness of the piezoelectric material to obtain a piezoelectric pillar array module with a substrate.

[0049] Step 2: Weld N-1 conductive wires 23 to the positive electrodes on the upper surface of the piezoelectric pillar array module with a substrate respectively, and insert the conductive wires 23 into the gaps of the piezoelectric pillars 24 to obtain the processed material I.

[0050] Step 3: Invert the processed material I and place it in a container of liquid polymer phase material, so that the surface of the lead-out electrode is immersed to a certain depth, but not completely immersed in the piezoelectric pillars, and there should be a margin. After curing, take it out to form the processed material II. The upper surface of the processed material II is the polymer phase material layer 1.

[0051] Step 4: Place the processed material II with the substrate facing up on a cutting machine, and cut through the substrate of the piezoelectric material along the X-axis and Y-axis to obtain the piezoelectric pillar array module 2.

[0052] Step 5: Pull out the N-1 conductive wires 23 in the gaps of the piezoelectric pillars 24 of the piezoelectric pillar array module 2, and weld them to the negative electrodes on the lower surfaces of the adjacent piezoelectric pillars 24 respectively to obtain the processed material III.

[0053] Electrically connect the positive electrode lead 21 and the negative electrode lead 22 to the first and the last piezoelectric small columns 24 respectively to obtain the processing material IV;

[0054] Step 6: Invert the processing material IV and place it in a vessel of liquid polymer phase material, submerge the end with the negative electrode to a certain depth, but do not completely submerge the piezoelectric small columns, leaving a margin. After curing, take it out. The sum of the thicknesses of the two surface polymer phase material layers is less than the thickness of the piezoelectric material, thus forming a hollow structure as a whole.

[0055] The following is the sensitive element of the high-sensitivity underwater acoustic receiving transducer obtained by the above preparation process. The specific structure is as follows:

[0056] As Figure 1 shown, it is composed of polymer phase material layers 1 covered on the upper surface and the lower surface and a piezoelectric small column array module 2. The piezoelectric small column array module 2 is located between the two polymer phase material layers 1. The piezoelectric small column array module 2 is composed of N piezoelectric small columns 24. Positive electrode leads 21, negative electrode leads 22, and N - 1 conductive wires 23 are electrically connected to the piezoelectric small columns 24. The top view of the piezoelectric small column 24 is square, rectangular, or circular.

[0057] The electrode connection method of the piezoelectric small columns 24 in the piezoelectric small column array module 2 is as Figure 2 shown. The conductive wires 23 led out from the upper surface electrodes of each piezoelectric small column 24 are all electrically connected to the lower surface electrodes of the adjacent piezoelectric small columns 24, connecting the N piezoelectric small columns 24 in the piezoelectric small column array module 2 in series. By connecting the N piezoelectric small columns 24 in the piezoelectric small column array module 2 in series, the output induction voltage of the sensitive element can be amplified by N times, thus improving the receiving sensitivity of the underwater acoustic transducer.

[0058] Covering the polymer phase material layer 1 on the upper surface and the lower surface of the piezoelectric small column array module 2 can, on the one hand, fix the piezoelectric small column array module 2 to prevent it from falling apart; on the other hand, avoid the unstable adhesion of the conductive wires 23 in the piezoelectric small column array module 2. At the same time, covering the polymer phase material layer 1 changes the boundary conditions of the piezoelectric small column array module 2 and amplifies the sound pressure in the sound field, improving the sensitivity of the transducer.

[0059] Traditional piezoelectric composite materials are often prepared by the cutting and filling method, and the filled polymer is usually epoxy resin phase. By cutting pure piezoelectric materials, the thickness vibration mode of the pure piezoelectric materials is changed to the longitudinal length expansion and contraction vibration mode of the piezoelectric small columns. However, due to the addition of polymers, the loss of the transducer is increased and the electromechanical coupling coefficient of the transducer is reduced. In the piezoelectric small column array module 2 of the present invention, the method of not adding polymers is adopted to further highlight the longitudinal length expansion and contraction vibration of the piezoelectric small columns 24, and at the same time avoid the loss caused by adding polymers, improving the sensitivity of the transducer.

[0060] The technical solution of the present invention will be further described below by way of examples and comparative examples, specifically as follows:

[0061] Example 1

[0062] A preparation method for a sensitive element of a high-sensitivity underwater acoustic receiving transducer includes the following steps:

[0063] Step 1: Select a piezoelectric material and polarize it in the Z-axis direction (perpendicular to the piezoelectric material sheet). A positive electrode is plated on the upper surface of the piezoelectric material, and a negative electrode is plated on the lower surface. Cut the piezoelectric material once along the X-axis direction, and the cutting depth should be less than the thickness of the piezoelectric material to obtain a piezoelectric small column array module with a substrate;

[0064] Step 2: Weld 1 wire 23 to the positive electrode on the upper surface of the piezoelectric small column array module with a substrate, and insert the wire 23 into the gap of the piezoelectric small column 24 to obtain Treatment Material I;

[0065] Step 3: Invert Treatment Material I and place it in a vessel containing a liquid polymer phase material, so that the surface of the lead-out electrode is immersed to a certain depth, but not completely immersed in the piezoelectric small column, and there should be a margin. After curing, take it out to form Treatment Material II, and the upper surface of Treatment Material II is a polymer phase material layer 1;

[0066] Step 4: Place Treatment Material II with the substrate facing up on a cutting machine and cut through the substrate of the piezoelectric material along the X-axis to obtain a piezoelectric small column array module 2;

[0067] Step 5: Pull out 1 wire 23 from the gap of the piezoelectric small column 24 of the piezoelectric small column array module 2 and weld it to the negative electrode on the lower surface of the adjacent piezoelectric small column 24 to obtain Treatment Material III;

[0068] Electrically connect the negative electrode lead 22 to the positive electrode of the piezoelectric small column 24 to obtain Treatment Material IV;

[0069] Step 6: Invert Treatment Material IV and place it in a vessel containing a liquid polymer phase material, so that the end containing the negative electrode is immersed to a certain depth, but not completely immersed in the piezoelectric small column, and there should be a margin. After curing, take it out, and the sum of the thicknesses of the polymer phase material layers on the two surfaces is less than the thickness of the piezoelectric material, thereby forming a hollow structure as a whole.

[0070] Comparative Example 1

[0071] A preparation method for a sensitive element of an underwater acoustic receiving transducer includes the following steps:

[0072] Select a piezoelectric small column 24, coat a positive electrode on the upper surface of the piezoelectric small column 24 and a negative electrode on the lower surface. Then, first place one end of the positive electrode in a vessel containing a liquid polymer phase material, take it out after curing, and then place one end of the negative electrode in the vessel containing the liquid polymer phase material, take it out after curing. The piezoelectric small column 24 cannot be completely immersed in the liquid polymer phase material and there should be a margin left to obtain the sensitive element of the underwater acoustic receiving transducer.

[0073] Comparative Example 2

[0074] A method for preparing a sensitive element of an underwater acoustic receiving transducer, comprising the following steps:

[0075] Step 1: Select a piezoelectric material, polarize it in the Z-axis (perpendicular to the piezoelectric material sheet) direction. The upper surface of the piezoelectric material is coated with a positive electrode and the lower surface is coated with a negative electrode. Cut the piezoelectric material once along the X-axis direction, and the cutting depth should be less than the thickness of the piezoelectric material to obtain a piezoelectric small column array module with a substrate.

[0076] Step 2: Invert the piezoelectric small column array module with a substrate and place it in a vessel containing a liquid polymer phase material, immerse it to a certain depth, and the piezoelectric small columns cannot be completely immersed and there should be a margin left. Take it out after curing to form Treatment Material I.

[0077] Step 3: Place Treatment Material I with the substrate facing up on a cutting machine and cut through the substrate of the piezoelectric material along the X-axis to obtain the piezoelectric small column array module 2.

[0078] Step 4: Invert the piezoelectric small column array module 2 and place it in a vessel containing a liquid polymer phase material, immerse the end containing the negative electrode to a certain depth, and the piezoelectric small columns cannot be completely immersed and there should be a margin left. Take it out after curing. The sum of the thicknesses of the polymer phase material layers on the two surfaces is less than the thickness of the piezoelectric material, thus forming a hollow structure as a whole.

[0079] Next, a comparative study is carried out on the sensitive element of the highly sensitive underwater acoustic receiving transducer in Example 1 and the sensitive elements of Comparative Example 1 and Comparative Example 2. The difference among the three is that in Example 1, two piezoelectric small columns are in series, in Comparative Example 1, there is one piezoelectric small column, and in Comparative Example 2, two piezoelectric small columns are in parallel. The structures of the three are as Figure 3 shown, and the specific research methods and results are as follows:

[0080] Conduct a feasibility analysis and simulation test on this sensitive element. Use finite element analysis software for simulation. Simplify the structure of the underwater acoustic transducer to be simulated, build a model in the finite element analysis software according to the simplified model, apply loads according to the actual situation for modal analysis, and the distribution of stress and displacement can be obtained. Conduct frequency domain analysis to obtain the performance parameters of the underwater acoustic transducer. The steps of the finite element analysis software in the design of the underwater acoustic transducer are asFigure 10 as shown

[0081] First, a simplified simulation model is constructed according to the structure of the transducer sensitive element, which is divided into two models for transmitting performance and receiving performance. The simulation model for analyzing the transmitting performance mainly consists of a piezoelectric sensitive element, a water area, and a perfectly matched layer, while the simulation model for analyzing the receiving performance consists of a sensitive element and a water area. Secondly, materials are assigned to the constructed simulation model. The piezoelectric material part uses PZT-5A piezoelectric ceramic, and the polymer part uses epoxy resin. Then, a multi-physics field is constructed, which can be divided into a pressure acoustics part, a solid mechanics part, and an electrostatics part. For the pressure acoustics part, methods such as external field calculation or setting a plane wave incident pressure field are adopted according to the analysis of transmitting or receiving performance; for the solid mechanics part, symmetric boundary conditions and mechanical damping are applied according to the structure; for the electrostatics part, a voltage or a floating potential is applied to the piezoelectric material part. After the physical field is constructed, the simulation model is meshed, and the free tetrahedral mesh and the swept distribution method are used for meshing. Different physical field structures correspond to different sizes of elements. Finally, the frequency domain scanning range is set for solving. After the solution is completed, the required performance parameters are obtained in the post-processing part to draw the final results.

[0082] To illustrate that the sensitive element can amplify the output induced voltage and thus improve the receiving sensitivity by connecting the electrodes of adjacent piezoelectric columns in series. The simulation comparison is carried out on a single piezoelectric column and two piezoelectric columns connected in series in turn. The water admittance curve and the receiving sensitivity curve of a single piezoelectric column are as Figure 4 and Figure 5 shown, and the water admittance curve and the receiving sensitivity curve of two piezoelectric columns connected in series are as Figure 6 and Figure 7 shown. It can be seen from the figure that the resonant frequency of a single piezoelectric column is 188 kHz, the maximum admittance can reach 0.25 mS, and the maximum receiving sensitivity in the working frequency band (i.e., the dynamic region) can reach -183 dB; the resonant frequency of two piezoelectric columns connected in series is 189 kHz, the maximum admittance can reach 0.16 mS, and the maximum receiving sensitivity in the working frequency band (i.e., the dynamic region) can reach -174 dB. Comparing Figure 4 and Figure 6 , it can be seen that the admittance value of two piezoelectric columns connected in series is lower than that of a single piezoelectric column. This is because the impedance becomes larger when the electrodes of two piezoelectric columns are connected in series, resulting in a lower admittance value at the resonant peak; if it is used as a receiving transducer, its output induced voltage will be amplified, thereby improving the sensitivity. Comparing Figure 5 and Figure 7 , it can be seen that the receiving sensitivity of two piezoelectric columns connected in series is generally higher than that of a single piezoelectric column, which further verifies the feasibility of amplifying the output induced voltage.

[0083] From Figure 8 and Figure 9 it can be seen that the resonance frequency of two piezoelectric columns connected in parallel is 190 kHz, the maximum admittance can reach 0.26 mS, and the maximum receiving sensitivity in the working frequency band (i.e., the dynamic region) can reach -189 dB. Compared with Embodiment 1, the peak admittance of two piezoelectric columns connected in parallel is much smaller than that of two piezoelectric columns connected in series, which is caused by their electrical connection method; at the same time, the receiving sensitivity of two piezoelectric columns connected in series is generally higher than that of two piezoelectric columns connected in parallel. Thus, it can be seen that the electrical series connection method can amplify the output induced voltage of the sensitive element and improve the sensitivity.

[0084] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations. The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the scope of protection is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims.

Claims

1. A sensitive element, comprising a polymer phase material layer (1), characterized in that, It further includes a piezoelectric pillar array module (2), and the polymer phase material layer (1) is used to fix the piezoelectric pillar array module (2); The piezoelectric pillar array module (2) is composed of a plurality of piezoelectric pillars (24), and the plurality of piezoelectric pillars (24) are sequentially electrically connected in series through conductive wires (23). The piezoelectric pillars (24) connected to the first and last conductive wires (23) are electrically connected to a positive electrode lead (21) and a negative electrode lead (22) respectively.

2. The sensitive element according to claim 1, characterized in that, The height of each piezoelectric pillar (24) is greater than its width.

3. The sensitive element according to claim 1, characterized in that, The upper surface of each piezoelectric pillar (24) is plated with a positive electrode, and the lower surface is plated with a negative electrode. The two ends of the conductive wire (23) are respectively electrically connected to the positive electrode and the negative electrode of two adjacent piezoelectric pillars (24). The positive electrode lead (21) is electrically connected to the positive electrode, and the negative electrode lead (22) is electrically connected to the negative electrode.

4. The sensitive element according to claim 1, characterized in that, The polymer phase material layers (1) are symmetrically arranged, and the piezoelectric pillar array module (2) is located between the two polymer phase material layers (1).

5. The sensitive element according to claim 4, characterized in that, The two polymer phase material layers (1) and the piezoelectric pillar array module (2) together form a hollow structure.

6. The sensitive element according to claim 1, characterized in that, The piezoelectric pillar (24) is made of piezoelectric ceramic or piezoelectric single crystal, and the cross-section of the piezoelectric pillar (24) is square, rectangular or circular.

7. The sensitive element according to claim 1, characterized in that, The polymer phase material layer (1) is an epoxy resin layer, a silicone rubber layer or a polyurethane layer.

8. A method for preparing the sensitive element according to claim 1, characterized in that, It includes the following steps: A positive electrode and a negative electrode are respectively plated on the upper surface and the lower surface of the piezoelectric material, and the piezoelectric material is polarized along the Z-axis direction to obtain a polarized piezoelectric material; The polarized piezoelectric material is cut along the X-axis and Y-axis directions, and the cutting depth is less than the thickness of the polarized piezoelectric material to obtain a piezoelectric pillar array module with a substrate; A conductive wire (23) is led out from the positive electrode of each piezoelectric pillar array module with a substrate to obtain a processing material I; One end of the processing material I containing the positive electrode is immersed in the liquid polymer phase material, and after the liquid polymer phase material is cured, it is taken out to obtain a processing material II; The substrate of the processing material II is cut through along the X-axis and Y-axis directions to obtain the piezoelectric pillar array module (2); The free ends of the conductive wires (23) on each piezoelectric pillar (24) of the piezoelectric pillar array module (2) are taken out and respectively electrically connected to the negative electrodes of the adjacent piezoelectric pillars (24) to obtain a processing material III; The positive electrode lead (21) and the negative electrode lead (22) are respectively electrically connected to the first and last piezoelectric pillars (24) to obtain a processing material IV; One end of the processing material IV containing the negative electrode is immersed in the liquid polymer phase material, and after the liquid polymer phase material is cured, it is taken out to obtain a sensitive element.

9. Application of the sensitive element according to claim 1 in preparing a high-sensitivity underwater acoustic receiving transducer.

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