Hydrophone based on flexible piezoelectric composite
By using parallel flexible piezoelectric composite material components, the problems of hydrophones being easily damaged and lacking sensitivity in complex underwater environments have been solved, achieving a hydrophone design with high sensitivity and low cost, adaptable to a variety of application scenarios.
Patent Information
- Application Number
- CN202610691570.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-19
- Publication Date
- 2026-08-25
AI Technical Summary
Existing hydrophones are prone to cracking and damage in complex underwater environments, making it difficult to achieve both high sensitivity and wide bandwidth response. Furthermore, their manufacturing processes are cumbersome and costly, and the low piezoelectric coefficient of flexible piezoelectric materials makes it difficult to meet the requirements for high sensitivity.
The flexible piezoelectric composite material component, which adopts a parallel arrangement, includes a ceramic porous framework structure and a polymer matrix, combined with an organic-inorganic dielectric layer. The piezoelectric elements have opposite polarization directions, which enhances mechanical flexibility and hydrostatic pressure sensitivity, making it suitable for complex application scenarios.
A highly sensitive hydrophone has been developed, which combines good mechanical flexibility and hydrostatic pressure sensitivity, making it suitable for various complex application scenarios and reducing the complexity and cost of the manufacturing process.
Smart Images
Figure CN122631202A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of acoustic sensing technology, and more specifically, relates to a hydrophone based on flexible piezoelectric composite materials. Background Technology
[0002] Hydrophones, also known as underwater acoustic sensors, are important underwater acoustic sensors that can detect, track, identify, and locate long-range, low-noise targets in water, playing a vital role in many fields such as ocean exploration, sonar systems, environmental monitoring, and military reconnaissance. However, with the rapid development of underwater wireless sensor networks, the performance requirements for hydrophones are gradually increasing. Summary of the Invention
[0003] In view of the technical problems existing in the background art, the first aspect of this application provides a hydrophone based on flexible piezoelectric composite material, including a piezoelectric material component; The piezoelectric material assembly includes a first sublayer and a second sublayer arranged in parallel, wherein the polarization directions of the first sublayer and the second sublayer are opposite in the thickness direction of the piezoelectric material assembly; the first sublayer and the second sublayer each independently include a piezoelectric sheet; The piezoelectric sheet includes a flexible piezoelectric composite material layer, which includes a flexible piezoelectric composite material; the flexible piezoelectric composite material includes a ceramic porous framework structure and a polymer matrix filled in the ceramic porous framework structure; an organic-inorganic dielectric layer is also included between the ceramic porous framework structure and the polymer matrix.
[0004] Therefore, the flexible piezoelectric composite material used in this application has a high piezoelectric coefficient, good mechanical flexibility and high static pressure sensitivity. When applied to hydrophones, it enables the hydrophones to adapt to various complex application scenarios while maintaining high sensitivity.
[0005] In some embodiments, the piezoelectric elements in the first sublayer and / or the second sublayer are connected in series.
[0006] In some embodiments, the number of piezoelectric elements in the first sublayer and the second sublayer is equal.
[0007] In some embodiments, the piezoelectric sheets in the first and second sublayers have the same thickness.
[0008] In some implementations, a first plane is included between the first sub-layer and the second sub-layer; In the first sub-layer and / or the second sub-layer, the elastic modulus of the piezoelectric sheet closer to the first plane is greater than that of the piezoelectric sheet farther from the first plane; In the first sublayer and / or the second sublayer, the density of the piezoelectric sheet closer to the first plane is greater than the density of the piezoelectric sheet farther from the first plane.
[0009] In some embodiments, the thickness of the piezoelectric sheet is 1mm-5mm.
[0010] In some embodiments, the piezoelectric element satisfies one or two of the following conditions: The diameter of the piezoelectric element is 20mm-40mm; The piezoelectric sheet has a length of 10mm-50mm in a first direction and a length of 10mm-50mm in a second direction; the first direction and the second direction are respectively perpendicular to the thickness direction of the piezoelectric material assembly.
[0011] In some embodiments, an auxiliary film is also included, the auxiliary film being located on at least one side of the piezoelectric material assembly; wherein, The auxiliary membrane includes a base membrane and electrode layers attached to both sides of the base membrane; Optionally, the base film includes a polyimide film; Optionally, the electrode layer may include one or both of copper and aluminum.
[0012] In some embodiments, the flexible piezoelectric composite material satisfies one or more of the following conditions: The ceramic porous framework structure includes lead zirconate titanate. The polymer matrix includes one or both of polydimethylsiloxane and polyurethane. The organic-inorganic dielectric layer comprises organic materials and inorganic fillers. The organic materials include one or more of polyvinylidene fluoride, poly(vinylidene fluoride-trifluoroethylene), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene), and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene). The inorganic fillers include one or more of carbon nanotubes and graphene.
[0013] In some embodiments, the flexible piezoelectric composite material satisfies one or more of the following conditions: The piezoelectric coefficient of the flexible piezoelectric composite material is greater than or equal to 120; The dielectric constant of the flexible piezoelectric composite material is 50-70 at 1 kHz; The elastic modulus of the flexible piezoelectric composite material is 20MPa-30MPa.
[0014] In some embodiments, the piezoelectric sheet further includes an electrode layer located on at least one side of the flexible piezoelectric composite material layer; Optionally, the electrode layer includes a metal layer, which includes one or both of silver and gold. Attached Figure Description
[0015] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a diagram showing the piezoelectric coefficient and dielectric constant of flexible piezoelectric composite materials. Figure 1 Figure (a) shows the piezoelectric coefficient of the flexible piezoelectric composite material; Figure 1 Figure (b) shows the dielectric constant of the flexible piezoelectric composite material.
[0016] Figure 2 This is a diagram showing the elastic modulus of flexible piezoelectric composite materials.
[0017] Figure 3 Finite element models for flexible piezoelectric composite materials and PZT piezoelectric ceramic materials.
[0018] Figure 4 The potential distribution diagrams of flexible piezoelectric composite materials and PZT piezoelectric ceramic materials under a static pressure of 1 Pa are shown.
[0019] Figure 5 This is a schematic diagram of the piezoelectric material layer.
[0020] Figure 6 This is a schematic diagram of a hydrophone based on flexible piezoelectric composite materials.
[0021] Figure 7 The graph shows the sensitivity test results of the hydrophones in Examples 1 and 2.
[0022] Figure 8 The diagram shows the acoustic reception directivity test results of the hydrophone in Example 1.
[0023] Figure 9 The graph shows the sensitivity test results of the hydrophones in Examples 3 and 4.
[0024] Figure label: 1. First sublayer; 11. Piezoelectric element a; 12. Piezoelectric element b; 2. Second sublayer; 21. Piezoelectric element c; 22. Piezoelectric element d; 31. Piezoelectric material assembly; 32. Encapsulating rubber; 33. Shielding mesh; 34. Decoupling support; 35. Base; 36. Preamplifier; 37. Locking cover; 38. Cable assembly. Detailed Implementation
[0025] The present application will be further described below with reference to specific embodiments. It should be understood that these specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.
[0026] The embodiments of this application are hereby disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.
[0027] The "range" disclosed in this application is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit, which defines the boundary of the particular range. Ranges defined in this way may or may not include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an undefined range, and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, each individually disclosed point or single value can itself serve as a lower limit or upper limit and can be combined with any other point or single value or with other lower limits or upper limits to form an undefined range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is expected that the ranges of 60~110 and 80~120 will also be understood. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges can all be expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between "0~5" have been listed herein, and "0~5" is merely a shortened representation of these numerical combinations. Additionally, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0028] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.
[0029] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.
[0030] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0031] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
[0032] Unless otherwise specified, in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0033] In this application, the terms "multiple" or "various" refer to two or more kinds.
[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion. Unless otherwise stated, the terms used in this application have their commonly understood meanings as understood by one of ordinary skill in the art. Unless otherwise stated, the numerical values of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).
[0035] The core function of a hydrophone relies on the sensing material inside the hydrophone. For example, the sensing material with piezoelectric properties inside the hydrophone can convert mechanical energy into electrical energy when subjected to force, and is therefore widely used in the field of underwater acoustic sensing.
[0036] In related technologies, hydrophones can be divided into hydrophones using rigid piezoelectric ceramic materials and hydrophones using flexible piezoelectric materials. Rigid piezoelectric ceramic materials used in hydrophones often employ rigid ceramic materials such as lead zirconate titanate (PZT), which possess excellent piezoelectric properties. However, ceramic materials are brittle and have extremely poor flexibility, making them prone to cracking and damage in complex underwater environments such as high-pressure impacts and mechanical vibrations. Furthermore, the mutual constraints of their transverse and longitudinal piezoelectric effects and their low voltage output limit the ability to simultaneously achieve high sensitivity and wide bandwidth response. In addition, hydrophones often require designs such as bending structures and composite resonant structures to adapt to various complex application scenarios, resulting in cumbersome manufacturing processes, high production costs, and limited large-scale applications.
[0037] The flexible piezoelectric materials used in hydrophones are mostly polyvinylidene fluoride (PVDF) and its copolymers as the core sensing materials. Although they have good mechanical flexibility and can adapt to complex surface bonding requirements and reduce noise interference, their piezoelectric coefficient is low and their piezoelectric performance is poor, making it difficult to meet the high sensitivity requirements in practical applications.
[0038] Based on this, the first aspect of this application provides a hydrophone based on a flexible piezoelectric composite material, the hydrophone based on the flexible piezoelectric composite material including a piezoelectric material component; The piezoelectric material assembly includes a first sublayer and a second sublayer arranged in parallel, with the first sublayer and the second sublayer having opposite polarization directions in the thickness direction of the piezoelectric material assembly; the first sublayer and the second sublayer each independently include a piezoelectric sheet; The piezoelectric sheet includes a flexible piezoelectric composite material layer, which includes a flexible piezoelectric composite material; the flexible piezoelectric composite material includes a ceramic porous framework structure and a polymer matrix filled in the ceramic porous framework structure; an organic-inorganic dielectric layer is also included between the ceramic porous framework structure and the polymer matrix.
[0039] The flexible piezoelectric composite material used in this application combines high piezoelectric coefficient, good mechanical flexibility, and high static pressure sensitivity. When applied to hydrophones, it enables the hydrophones to adapt to various complex application scenarios while maintaining high sensitivity.
[0040] The following section provides further explanation of the structure and performance of flexible piezoelectric composite materials and hydrophones based on flexible piezoelectric composite materials.
[0041] Flexible piezoelectric composite materials In some implementations, the flexible piezoelectric composite material satisfies one or more of the following conditions: Ceramic porous framework structures include lead zirconate titanate; The polymer matrix includes one or both of polydimethylsiloxane and polyurethane; The organic-inorganic dielectric layer includes organic materials and inorganic fillers. The organic materials include one or more of polyvinylidene fluoride, poly(vinylidene fluoride-trifluoroethylene), poly(vinylidene fluoride-trifluoroethylene-trifluorochloroethylene), and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene); the inorganic fillers include one or more of carbon nanotubes and graphene.
[0042] Therefore, by controlling the composition of each part of the flexible piezoelectric composite material within the aforementioned range, the flexible piezoelectric composite material can possess both high piezoelectric coefficient, good mechanical flexibility, and high static pressure sensitivity.
[0043] In some embodiments, the preparation steps of the flexible piezoelectric composite material may include: S100. The raw material for ceramic porous framework structure, such as lead zirconate titanate, is sintered at 1000℃-1400℃ for 1h-4h to obtain sintered product; the sintered product is coarsely ground in a mortar and then transferred to a ball mill for ball milling, and after drying, ceramic porous framework structure powder is obtained. S200: The powder obtained in step S100 is uniformly dispersed in deionized water by stirring and ultrasonic treatment to obtain a slurry; then surfactant, ammonium chloride and dilute hydrochloric acid are added to the slurry; then the mechanical stirring speed is increased to introduce air into the slurry to make it foam; the foamed slurry is transferred to a mold, and after demolding, it is placed at room temperature to dry to obtain a dry skeleton; the dry skeleton is sintered to obtain a ceramic porous skeleton structure. S300: Prepare a first precursor solution containing organic materials such as poly(vinylidene fluoride-trifluoroethylene-trifluorochloroethylene) and inorganic fillers such as carbon nanotubes. Immerse the ceramic porous framework structure obtained in step S200 in the first precursor solution. After immersion, place it in a forced-air drying oven to dry, and obtain a framework structure with an organic-inorganic dielectric layer on the surface of the pore wall. S400: Prepare a second precursor solution containing a polymer matrix such as polydimethylsiloxane; place the skeleton structure with an organic-inorganic dielectric layer coated on the pore wall surface obtained in step S300 into the second precursor solution; in a vacuum environment, pour the polymer matrix into the interior of the ceramic skeleton; after curing, obtain the flexible piezoelectric composite material of this application.
[0044] In some embodiments, the piezoelectric coefficient of the flexible piezoelectric composite material is greater than or equal to 120.
[0045] As an example, the piezoelectric coefficient of flexible piezoelectric composite materials can be 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, etc., or a range of any two of the above values.
[0046] In some embodiments, the dielectric constant of the flexible piezoelectric composite material is 50-70 at 1 kHz.
[0047] As an example, the dielectric constant of the flexible piezoelectric composite material at 1 kHz can be 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, etc., or a range consisting of any two of the above values.
[0048] Specifically, the piezoelectric coefficient and dielectric constant of flexible piezoelectric composite materials can be tested using the following methods. As an example, five hydrophones were disassembled, the piezoelectric material components were removed, and the piezoelectric elements were separated. Then, the piezoelectric coefficient of the flexible piezoelectric composite material in each piezoelectric element was tested using a quasi-static method, and the dielectric constant was tested using the parallel plate capacitance method. The test results are as follows: Figure 1 As shown.
[0049] Depend on Figure 1 As shown in Figure (a), the average piezoelectric coefficient of the flexible piezoelectric composite material d 33 Keep it above 120; Figure 1 As shown in Figure (b), the dielectric constant of the flexible piezoelectric composite material is 50-70 at 1 kHz.
[0050] In some embodiments, the elastic modulus of the flexible piezoelectric composite material is 20 MPa-30 MPa.
[0051] As an example, the elastic modulus of flexible piezoelectric composite materials can be 20MPa, 21MPa, 22MPa, 23MPa, 24MPa, 25MPa, 26MPa, 27MPa, 28MPa, 29MPa, 30MPa, etc., or a range consisting of any two of the above values.
[0052] Specifically, the elastic modulus of flexible piezoelectric composite materials can be tested using a uniaxial tensile test, and the test results are as follows: Figure 2 As shown.
[0053] Depend on Figure 2 It can be seen that the average elastic modulus of the flexible piezoelectric composite material is 27.7 MPa.
[0054] Furthermore, as a free-flow sensing structure, the sensitivity of the piezoelectric element depends on its sensitivity to hydrostatic pressure. To verify the receiving response of the flexible piezoelectric composite material used in this application to underwater acoustic signals, the acoustic receiving characteristics of a circular piezoelectric element can be simulated using finite element software. Moreover, a rigid lead zirconate titanate (PZT) piezoelectric ceramic material can be used as a comparison to establish... Figure 3The finite element models of two circular piezoelectric sheets made of different materials are shown.
[0055] in, Figure 3 In the diagram, Y1 is a circular piezoelectric sheet using a flexible piezoelectric composite material, and Y2 is a circular piezoelectric sheet using PZT piezoelectric ceramic material. For ease of analysis, Figure 3 The finite element model of only 1 / 4 of the circular piezoelectric sheet is shown.
[0056] A three-dimensional static pressure of 1 Pa, directed towards the thickness of the piezoelectric elements Y1 and Y2, was applied to their outer surfaces to simulate the output characteristics of the piezoelectric elements under sound pressure. The potential distributions of the two elements are as follows: Figure 4 As shown.
[0057] Depend on Figure 4 It is known that under three-dimensional static pressure, the potential output of a circular piezoelectric sheet using PZT piezoelectric ceramic material is small and can be basically ignored. This is because the longitudinal and transverse piezoelectric properties of the circular piezoelectric sheet using PZT piezoelectric ceramic material cancel each other out, meaning that the piezoelectric sheet has virtually no voltage output under three-dimensional static pressure. The output potential of a circular piezoelectric sheet using flexible piezoelectric composite material is significantly greater than that of a circular piezoelectric sheet using PZT piezoelectric ceramic material. This is because the longitudinal piezoelectric constant of the piezoelectric sheet using the flexible piezoelectric composite material used in this application is originally higher than the transverse piezoelectric constant, exhibiting higher static pressure sensitivity, and allowing for direct acoustic reception using thickness mode.
[0058] Hydrophone based on flexible piezoelectric composite materials In some embodiments, the hydrophone based on the flexible piezoelectric composite material includes a piezoelectric material assembly; the piezoelectric material assembly includes a first sublayer and a second sublayer arranged in parallel, the first sublayer and the second sublayer having opposite polarization directions in the thickness direction of the piezoelectric material assembly; the first sublayer and the second sublayer each independently include a piezoelectric sheet.
[0059] As an example, such as Figure 5 As shown, the piezoelectric material assembly includes a first sublayer 1 and a second sublayer 2 stacked together. The first sublayer 1 and the second sublayer 2 are arranged in parallel, and the polarization directions of the first sublayer 1 and the second sublayer 2 are opposite in the Z direction (defined as the thickness direction of the piezoelectric material assembly).
[0060] In some implementations, the piezoelectric elements are connected in series in the first sublayer and / or the second sublayer.
[0061] As an example, such as Figure 5As shown, the piezoelectric material assembly may include four piezoelectric sheets. Specifically, the first sub-layer 1 may include piezoelectric sheets a 11 and b 12 stacked and connected in series, and the second sub-layer 2 may include piezoelectric sheets c 21 and d 22 stacked and connected in series. Piezoelectric sheets a 11 and b 12 have the same polarization direction, and piezoelectric sheets c 21 and d 22 have the same polarization direction; however, piezoelectric sheets a 11 and c 21 have opposite polarization directions.
[0062] Therefore, the signal of a hydrophone based on flexible piezoelectric composite materials is transmitted through the intermediate electrode (such as...). Figure 5 The A+) is drawn out, and the outermost two electrodes serve as the negative electrodes (e.g., A+). Figure 5 (A-). In the receiving state, piezoelectric elements with the same polarization direction are connected in series and stacked, while two sets of piezoelectric elements with opposite polarization directions are connected in parallel for output (the charge increases but the voltage remains unchanged when connected in parallel). Therefore, when the piezoelectric material assembly includes 4 piezoelectric elements, its output voltage is twice that of a single piezoelectric element.
[0063] In some implementations, the number of piezoelectric elements in the first sublayer and the second sublayer is equal.
[0064] This allows the hydrophone to output a stable voltage.
[0065] In some embodiments, the piezoelectric sheets in the first and second sublayers have the same thickness.
[0066] This allows the hydrophone to output a stable voltage.
[0067] In some implementations, a first plane is included between the first sublayer and the second sublayer; In the first sublayer and / or the second sublayer, the elastic modulus of the piezoelectric sheet closer to the first plane is greater than that of the piezoelectric sheet farther from the first plane. In the first sublayer and / or the second sublayer, the density of piezoelectric sheets closer to the first plane is greater than the density of piezoelectric sheets farther from the first plane.
[0068] The piezoelectric elements closer to the first plane have a higher elastic modulus and density, indicating better piezoelectric performance but poorer flexibility. Conversely, the piezoelectric elements farther from the first plane have a lower elastic modulus and density, indicating poorer piezoelectric performance but better flexibility. Therefore, this facilitates impedance matching, reduces acoustic signal reflection, and consequently improves the signal receiving sensitivity of the hydrophone.
[0069] It is understandable that when the first sub-layer and the second sub-layer are stacked, the first plane refers to the common plane between the two.
[0070] In some embodiments, the piezoelectric sheet further includes an electrode layer located on at least one side of the flexible piezoelectric composite material layer.
[0071] Therefore, the electrode layer is used to extract the voltage generated by the piezoelectric element.
[0072] As an example, the electrode layer includes a metal layer, which may include one or both of silver and gold.
[0073] In some implementations, the hydrophone may include a circular hydrophone, a square hydrophone, or a hydrophone of any other shape.
[0074] When the hydrophone is a circular hydrophone, the piezoelectric element used in the hydrophone is circular in shape.
[0075] In some embodiments, the thickness of the piezoelectric sheet is 1mm-5mm, and the diameter of the piezoelectric sheet is 20mm-40mm.
[0076] As an example, the thickness of the piezoelectric sheet can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc., or a range consisting of any two of the above values.
[0077] As an example, the diameter of the piezoelectric element can be 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, 34mm, 36mm, 38mm, 40mm, etc., or a range consisting of any two of the above values.
[0078] In some embodiments, the circular hydrophone includes a piezoelectric material assembly 31, an encapsulating rubber 32, a shielding mesh 33, a decoupling support 34, a base 35, a preamplifier 36, a locking cover 37, and a cable assembly 38.
[0079] As an example, such as Figure 6 As shown, the piezoelectric material assembly 31 of the circular hydrophone includes the aforementioned piezoelectric sheet; a decoupling support 34 is fixedly disposed on at least one side of the piezoelectric material assembly 31 to suspend the piezoelectric material assembly 31 and reduce unnecessary coupling interference between different parts of the circuit. A shielding mesh 33 is disposed outside the piezoelectric material assembly 31 to cover the piezoelectric material assembly 31 and provide electrical shielding to reduce the impact of external electromagnetic interference on the performance of the piezoelectric material assembly 31. Encapsulating rubber 32 is disposed outside the piezoelectric material assembly 31, the shielding mesh 33, and the decoupling support 34 to fix the internal structure of the hydrophone.
[0080] A base 35 is fixedly mounted on one side of the encapsulating rubber 32. A preamplifier 36 is fixedly mounted inside the base 35. The preamplifier 36 is electrically connected to the piezoelectric material assembly 31 and is used to amplify the induced charge of the piezoelectric material assembly 31 to increase the output voltage. A cable assembly 38 is fixedly mounted on a locking cover 37, which can be snapped into one end of the base 35. When the locking cover 37 is snapped into the base 35, the cable assembly 38 can be electrically connected to the preamplifier 36. An oscilloscope is connected to the cable assembly 38 to display the induced charge generated by the piezoelectric material assembly 31.
[0081] In some implementations, the assembly process of the circular hydrophone includes the following steps: (1) Component inspection Appearance: The surfaces of all parts should be smooth and clean, free from scratches, bumps, burrs and other appearance defects, so as not to affect assembly and appearance.
[0082] Dimensions: The dimensions, tolerances, and surface roughness of all components must conform to the specifications in the machining drawings. Special attention should be paid to verifying critical mating dimensions; all mating parts must undergo pre-assembly inspection; any non-conforming components must be reworked and corrected.
[0083] (2) Inspection of piezoelectric elements Appearance: The piezoelectric sheet should be free from defects such as cracks and missing corners, with a smooth and uniform surface coating and clear and conspicuous positive and negative markings.
[0084] Piezoelectric properties: Test electroacoustic performance parameters such as piezoelectric constant, and screen according to the test standards.
[0085] (3) Cleaning of parts Before assembly, all parts must be thoroughly cleaned. Machining parts (including metal parts, electrode plates, plastic products, etc.) can be cleaned using an ultrasonic cleaner. For parts that are prone to rust or highly absorbent, they can be cleaned by wiping with alcohol and then allowed to air dry before use.
[0086] The surface of circular piezoelectric elements is usually coated with silver. Cleaning primarily involves wiping with alcohol. Take care not to damage the silver coating during cleaning. After cleaning, allow them to air dry for later use.
[0087] (4) Assembly and bonding requirements Pre-assembly is required before formal assembly. This involves trial assembly of each component without the use of adhesives to ensure proper fit. The piezoelectric material components of this hydrophone have a low elastic modulus, necessitating the use of a low-modulus flexible epoxy resin adhesive to ensure bonding strength while minimizing the risk of cracking. During formal assembly, apply a thin, even layer of epoxy resin adhesive to the mating surfaces of the components, avoiding excessive application. After assembling according to the design drawings and confirming accuracy, prepare to apply prestress.
[0088] (5) Application of prestress Prestress must be applied during the bonding of piezoelectric material components to eliminate bonding gaps and improve bonding accuracy and reliability. The magnitude of the prestress should be determined based on the mechanical properties of the flexible piezoelectric composite material, minimizing its impact on material properties while meeting assembly accuracy requirements. Prestress should be applied using a pressurizing device according to calculated values, with close monitoring of the material's appearance during the process to avoid deformation and damage due to excessive pressure.
[0089] (6) Bonding and curing After applying prestress, promptly remove any excess epoxy resin extruded from the periphery of the piezoelectric material assembly. Place the assembled hydrophone in the mold and cast a rubber encapsulation. The curing temperature must be strictly controlled at 70℃, with a deviation not exceeding ±1℃.
[0090] (7) Welding wires After the hydrophone has cured, the electrode plates are soldered with lead wires. During soldering, the positive and negative poles of the piezoelectric elements must be clearly identified to prevent incorrect soldering; the solder joints should be bright and smooth to effectively reduce the risk of incomplete soldering and short circuits.
[0091] (8) Testing and inspection in air After curing and wire soldering, preliminary electrical parameter tests are performed on the hydrophone, focusing on the resonant frequency and impedance characteristics to preliminarily determine whether it meets the design requirements. Electrical performance tests must be conducted in air, and the sample should be placed on a low-impedance support material such as foam to ensure that the radiating surface and the tail load do not contact the high-impedance hard interface, thus avoiding affecting test accuracy.
[0092] In some implementations, the packaging process for a circular hydrophone includes the following steps: (1) Mold inspection The mold is crucial for the encapsulation of disc hydrophones, and its machining precision and surface finish directly determine the external dimensions and appearance of the encapsulated rubber. During inspection, the appearance of the mold is checked first to ensure that the surfaces of each machined part are flat and free from defects such as scratches and dents, with a focus on checking the inner surface of the mold; then, according to the drawing requirements, all dimensions, tolerances, and surface roughness are verified, with a focus on checking key mating dimensions and performing pre-assembly. Any unqualified parts must be reworked and corrected.
[0093] (2) Mold pre-assembly The molds that have passed inspection are pre-assembled and installed on the disc hydrophones to check the smoothness of the installation and the rationality of the mold design. The focus is on checking for leaks after assembly, predicting the possibility of glue leakage and the feasibility of handling it. If there are design defects, they need to be modified in time or remedial measures should be taken.
[0094] (3) Cleaning of bonding surfaces Before encapsulation, the exposed surfaces of the hydrophone and the polyurethane rubber bonding surface must be cleaned to remove oil stains and dirt.
[0095] (4) Applying the transition agent by brush After cleaning, a transition agent needs to be applied to the surface of the hydrophone to improve the adhesion with the polyurethane rubber. Use a brush to apply the transition agent evenly to the outer surface of the hydrophone, ensuring that the brushed surface is complete and without omissions. After brushing, let it stand at room temperature until the transition agent hardens and forms a film (about 10-20 minutes) before proceeding to the next step.
[0096] (5) Mold assembly Install the mold onto the disc hydrophone and apply silicone rubber sealant to the gaps in the mold. Place the molded hydrophone into a drying oven, level its radiating surface, and let it stand for the silicone rubber to cure.
[0097] (6) Preheating After the silicone rubber has cured, turn on the drying oven to preheat it to 60°C for 1 hour.
[0098] (7) Preparation of polyurethane rubber Polyurethane rubber formulation is a key encapsulation process. During the preheating of the hydrophone, the formulation of the polyurethane rubber prepolymer is completed by professionals.
[0099] (8) Pouring Slowly pour the liquid prepolymer into the mold using a glass beaker. Immediately after pouring, check the outer surface of the mold for any leaks. If any leaks are found, seal them immediately. At the same time, check the surface of the poured liquid for any air bubbles and clean them up promptly if found.
[0100] (9) Curing and demolding After confirming that there is no glue leakage in the mold, heat it in a drying oven at 70℃ for 20 hours to cure it. After demolding, check the rubber sealing surface, focusing on checking for bubbles and defects. Repair any defects in a timely manner.
[0101] (10) Basic performance test After packaging, the basic electroacoustic characteristics of the hydrophone, such as capacitance, air impedance, and insulation strength, are tested. Once the test is passed, it is ready to proceed to the subsequent underwater acoustic testing stage.
[0102] Example parameters: The disc hydrophone uses a Φ30mm×2mm piezoelectric sheet, with a maximum diameter of approximately 45mm after encapsulation, a height of 150mm-160mm, and a weight of approximately 600g.
[0103] When the hydrophone is a square hydrophone, the piezoelectric element used in the hydrophone can be square in shape.
[0104] In some embodiments, the thickness of the piezoelectric sheet is 1mm-5mm, the length of the piezoelectric sheet in a first direction is 10mm-50mm, and the length in a second direction is 10mm-50mm; the first direction and the second direction are respectively perpendicular to the thickness direction of the piezoelectric material assembly.
[0105] As an example, the thickness of the piezoelectric sheet can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc., or a range consisting of any two of the above values.
[0106] As an example, the length of the piezoelectric sheet in the first direction can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, etc., or a range consisting of any two of the above values.
[0107] As an example, the length of the piezoelectric sheet in the second direction can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, etc., or a range consisting of any two of the above values.
[0108] As an example, the square hydrophone uses a piezoelectric element with dimensions of 40mm×20mm×2.5mm. The assembly process of the square hydrophone can refer to the assembly process of the aforementioned round hydrophone, and will not be repeated here.
[0109] In some embodiments, the hydrophone further includes an auxiliary membrane located on at least one side of the piezoelectric material assembly; wherein the auxiliary membrane includes a base membrane and electrode layers attached to both sides of the base membrane; optionally, the base membrane includes a polyimide membrane; optionally, the electrode layers include one or both of metallic copper and metallic aluminum.
[0110] Since it is difficult to directly weld wires onto the surface of flexible piezoelectric composite material layers, a polyimide (PI) film covered with copper electrodes can be used to assist in connecting the wires.
[0111] The specific operation steps include: preparing a PI film with the required copper electrode pattern through a series of processes such as material preparation, drilling, exposure, development, etching, application of insulating film, and electroless gold plating. Short wires of appropriate length are welded to the ends of the copper-clad PI film, and the two copper-clad PI films are connected by welding wires to form the external electrodes of two parallel piezoelectric sheets.
[0112] Take another copper-clad PI film on both sides as the common internal electrode for the two piezoelectric material sheets. Bond the two piezoelectric materials to the copper-clad PI film with conductive silver paste and adhesive. Note that the polarization directions of the two piezoelectric materials need to be opposite to form a parallel connection to make a piezoelectric material assembly.
[0113] To improve the watertightness of the square hydrophone, short lead wires are welded to cables; then, thermoplastic polyurethane elastomer material is injected around the piezoelectric material components and a certain length of cable using a mold, and after curing, the square hydrophone is made.
[0114] Example The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0115] Example 1 A circular hydrophone is disclosed, which uses a piezoelectric element with a diameter of 30mm and a diameter of 2mm. The hydrophone, after encapsulation, has a maximum diameter of 45mm, a height of approximately 160mm, and a weight of approximately 600g.
[0116] Example 2 A square hydrophone, wherein the square hydrophone uses a piezoelectric element with dimensions of 40mm×20mm×2.5mm.
[0117] In Examples 1 and 2, the piezoelectric sheets used include a flexible piezoelectric composite material layer, which comprises a flexible piezoelectric composite material. The flexible piezoelectric composite material includes a porous lead zirconate titanate framework structure and polydimethylsiloxane filled within the porous lead zirconate titanate framework structure. An organic-inorganic dielectric layer is also included between the porous lead zirconate titanate framework structure and the polydimethylsiloxane. This organic-inorganic dielectric layer comprises poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) and carbon nanotube fillers. A metallic silver layer is also disposed on both sides of the flexible piezoelectric composite material layer.
[0118] The flexible piezoelectric composite material has a piezoelectric coefficient greater than 120, a dielectric constant in the range of 50-70 at 1 kHz, and an elastic modulus of 27.7 MPa.
[0119] The piezoelectric material assemblies used in Examples 1 and 2 consist of four piezoelectric sheets.
[0120] Specifically, the piezoelectric material assemblies of Embodiments 1 and 2 include a first sublayer 1 and a second sublayer 2 stacked together. The first sublayer 1 and the second sublayer 2 are arranged in parallel, and the polarization directions of the first sublayer 1 and the second sublayer 2 are opposite in the Z direction (defined as the thickness direction of the piezoelectric material assembly).
[0121] The first sublayer 1 may include piezoelectric sheets a 11 and b 12 stacked and connected in series, and the second sublayer 2 may include piezoelectric sheets c 21 and d 22 stacked and connected in series. Piezoelectric sheets a 11 and b 12 have the same polarization direction, piezoelectric sheets c 21 and d 22 have the same polarization direction, and piezoelectric sheets a 11 and c 21 have opposite polarization directions.
[0122] Meanwhile, the elastic modulus and density of piezoelectric a 11 are greater than those of piezoelectric b 12; the elastic modulus and density of piezoelectric c 21 are greater than those of piezoelectric d 22.
[0123] Performance testing 1. The hydrophones of Examples 1 and 2 were tested respectively in the sound source frequency band of 100 Hz-5 kHz. The sensitivity test results are as follows: Figure 7 As shown.
[0124] Depend on Figure 7 It can be seen that the acoustic receiving sensitivity of the hydrophones in Embodiment 1 and Embodiment 2 can be maintained between -187.2dB and -185.7dB and -188.4dB and -187.1dB, respectively; and the acoustic receiving sensitivity of Embodiment 1 and Embodiment 2 has good frequency stability within the operating frequency band.
[0125] 2. The acoustic reception directivity of the hydrophone in Example 1 was tested at 5kHz. The test results are as follows: Figure 8 As shown.
[0126] Depend on Figure 8 It can be seen that the hydrophone is omnidirectional, and the unilateral omnidirectional and hemispherical directivity fluctuations reach 1.68dB, indicating that the hydrophone can achieve high-sensitivity reception of sound wave signals from all directions.
[0127] Example 3-Example 4 The difference between Example 3 and Example 1 is that the elastic modulus and density of piezoelectric sheet a 11 are less than the elastic modulus and density of piezoelectric sheet b 12; and the elastic modulus and density of piezoelectric sheet c 21 are less than the elastic modulus and density of piezoelectric sheet d 22.
[0128] The difference between Example 4 and Example 1 is that the elastic modulus and density of piezoelectric sheet a 11 are equal to the elastic modulus and density of piezoelectric sheet b 12; and the elastic modulus and density of piezoelectric sheet c 21 are equal to the elastic modulus and density of piezoelectric sheet d 22.
[0129] The hydrophones of Examples 3 and 4 were tested respectively in the sound source frequency band of 100 Hz-5 kHz. The sensitivity test results are as follows: Figure 9 As shown.
[0130] Depend on Figure 9 It can be seen that the acoustic receiving sensitivity of the hydrophones in Examples 3 and 4 is between -191.1 dB and -189.6 dB and between -192.6 dB and -191 dB, respectively, which is significantly lower than that in Examples 1 and 2.
[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A hydrophone based on flexible piezoelectric composite material, characterized in that, Including piezoelectric material components; The piezoelectric material assembly includes a first sublayer and a second sublayer arranged in parallel, wherein the polarization directions of the first sublayer and the second sublayer are opposite in the thickness direction of the piezoelectric material assembly; the first sublayer and the second sublayer each independently include a piezoelectric sheet; The piezoelectric sheet includes a flexible piezoelectric composite material layer, which includes a flexible piezoelectric composite material; the flexible piezoelectric composite material includes a ceramic porous framework structure and a polymer matrix filled in the ceramic porous framework structure; an organic-inorganic dielectric layer is also included between the ceramic porous framework structure and the polymer matrix.
2. The hydrophone according to claim 1, characterized in that, In the first sublayer and / or the second sublayer, each of the piezoelectric elements is connected in series.
3. The hydrophone according to claim 1 or 2, characterized in that, The piezoelectric material assembly satisfies one or two of the following conditions: The number of piezoelectric elements in the first sublayer and the second sublayer is equal; The piezoelectric sheets in the first and second sub-layers have the same thickness.
4. The hydrophone according to any one of claims 1-3, characterized in that, A first plane is included between the first sub-layer and the second sub-layer; In the first sub-layer and / or the second sub-layer, the elastic modulus of the piezoelectric sheet closer to the first plane is greater than that of the piezoelectric sheet farther from the first plane; In the first sublayer and / or the second sublayer, the density of the piezoelectric sheet closer to the first plane is greater than the density of the piezoelectric sheet farther from the first plane.
5. The hydrophone according to any one of claims 1-4, characterized in that, The thickness of the piezoelectric sheet is 1mm-5mm.
6. The hydrophone according to claim 5, characterized in that, The piezoelectric element satisfies one or two of the following conditions: The diameter of the piezoelectric element is 20mm-40mm; The piezoelectric sheet has a length of 10mm-50mm in a first direction and a length of 10mm-50mm in a second direction; the first direction and the second direction are respectively perpendicular to the thickness direction of the piezoelectric material assembly.
7. The hydrophone according to any one of claims 1-6, characterized in that, It also includes an auxiliary film located on at least one side of the piezoelectric material assembly; wherein, The auxiliary membrane includes a base membrane and electrode layers attached to both sides of the base membrane; Optionally, the base film includes a polyimide film; Optionally, the electrode layer may include one or both of copper and aluminum.
8. The hydrophone according to any one of claims 1-7, characterized in that, The flexible piezoelectric composite material satisfies one or more of the following conditions: The ceramic porous framework structure includes lead zirconate titanate. The polymer matrix includes one or both of polydimethylsiloxane and polyurethane. The organic-inorganic dielectric layer comprises organic materials and inorganic fillers. The organic materials include one or more of polyvinylidene fluoride, poly(vinylidene fluoride-trifluoroethylene), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene), and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene). The inorganic fillers include one or more of carbon nanotubes and graphene.
9. The hydrophone according to any one of claims 1-8, characterized in that, The flexible piezoelectric composite material satisfies one or more of the following conditions: The piezoelectric coefficient of the flexible piezoelectric composite material is greater than or equal to 120; The dielectric constant of the flexible piezoelectric composite material is 50-70 at 1 kHz; The elastic modulus of the flexible piezoelectric composite material is 20MPa-30MPa.
10. The hydrophone according to any one of claims 1-9, characterized in that, The piezoelectric element further includes an electrode layer, which is located on at least one side of the flexible piezoelectric composite material layer; Optionally, the electrode layer includes a metal layer, which includes one or both of silver and gold.