Cap cilia MEMS vector hydrophone

Abstract

The invention relates to the technical field of MEMS (Micro Electro Mechanical System) sensors, and discloses a cap cilia MEMS vector hydrophone, which comprises cap cilia used for sensing sound to generate vibration for transmission; the center mass block is arranged at the bottom of the cap-shaped cilium, the cap-shaped cilium is located in the center of the top of the center mass block, and the center mass block is used for receiving vibration transmitted by the cap-shaped cilium and diffusing the vibration; the four cantilever beams are fixedly connected to the front face, the rear face, the left face and the right face of the center mass block respectively and used for receiving vibration transmitted by the center mass block and generating deformation. And the square frame is arranged outside the four cantilever beams. The cap-shaped cilia has a larger sound wave receiving area than the traditional cilia, the cap-shaped structure can generate larger on-beam stress on the cantilever beam when receiving sound pressure signals with the same size, so that the piezoresistor generates larger resistance change, the hydrophone is simple and mature in manufacturing process, the cap-shaped cilia does not need secondary integration, and the cost is low. And the consistency of the hydrophone is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-electro-mechanical system sensor, in particular to a capillary MEMS vector hydrophone. BACKGROUND

[0002] As an acoustic sensor capable of synchronously picking up scalar sound pressure and vector particle vibration information in underwater sound field, the vector hydrophone has important application value in underwater target positioning, sonar detection and marine environment monitoring fields.

[0003] In recent years, with the development of MEMS technology, it has become a hot spot to apply MEMS technology to the development of vector hydrophones. The vector hydrophone based on MEMS technology has the advantages of small size, low power consumption, low cost, easy batch production and integration array. At present, the mainstream MEMS vector hydrophone adopts the principle of bionics, simulates the sensing mechanism of fish lateral line, and is made by micro-machining process. A cantilever beam-center mass structure is integrated with a "cilium" structure to pick up underwater particle vibration signals. The vibration of the cilium drives the cantilever beam to deform, and the piezoresistive resistor (such as a Wheatstone bridge) arranged on the cantilever beam converts the mechanical deformation into an electrical signal output.

[0004] In the prior art, the sensitivity and working bandwidth of the hydrophone are two key core performance indicators. In order to improve the sensitivity of the hydrophone (especially the low-frequency hydrophone), an effective way is to increase the size and equivalent mass of the cilium structure, for example, the cap-shaped structure in the present application is used to increase the sound receiving area and the coupling ability with the water medium.

[0005] However, this design idea faces an inherent technical bottleneck. In the case of a certain cantilever beam stiffness, the significant increase of the equivalent mass will inevitably lead to a substantial decrease of the natural frequency of the sensitive structure of the hydrophone. The decrease of the natural frequency will seriously limit the effective working bandwidth of the hydrophone, resulting in its inability to meet the preset detection frequency range requirement. Therefore, the prior art generally has the contradiction between the improvement of sensitivity and the expansion of working bandwidth, which is difficult to increase the cilium structure to obtain high sensitivity while still maintaining a wide working bandwidth. Therefore, the present application provides a cap-shaped cilium MEMS vector hydrophone to solve the problems in the prior art. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a cap-shaped cilium MEMS vector hydrophone to solve the problems in the above background art.

[0007] To achieve the above purpose, the present application is realized by the following technical scheme: a cap-shaped cilium MEMS vector hydrophone, comprising: a cap-shaped cilium for sensing sound vibration for transmission; a center mass block arranged at the bottom of the cap-shaped fiber, the cap-shaped fiber being arranged at the top center of the center mass block, the center mass block being configured to receive vibration transmitted by the cap-shaped fiber and diffuse the vibration; four cantilever beams respectively fixedly connected to the front, rear, left and right four sides of the center mass block, the four cantilever beams being configured to receive vibration transmitted by the center mass block and generate deformation; a square frame arranged outside the four cantilever beams, the inner side of the square frame being fixedly connected to the ends of the four cantilever beams away from the cap-shaped fiber.

[0008] Preferably, the outer middle side of the cap-shaped fiber is protruded in a cap shape, the cap-shaped fiber is made of a resin material, and the cantilever beam is made of a silicon material.

[0009] Preferably, the top of the square frame and the four cantilever beams are arranged with an electric bridge, and two resistors are arranged on the top electric bridge of each cantilever beam.

[0010] Preferably, the four cantilever beams are provided with a flexible connection structure at the connecting root of the cantilever beams and the center mass block.

[0011] Preferably, the flexible connection structure is at least one microstructure form of a narrow waist structure, a stress concentration design or a flexible film hinge.

[0012] Preferably, the flexible connection structure is configured to, as a stress concentration point, enhance the stress of the root of the cantilever beam by locally reducing the cross-sectional modulus of the cantilever beam when the cap-shaped fiber structure swings and transmits a torque to the cantilever beam. Preferably, the flexible connection structure is configured to, as a stress concentration point, enhance the stress of the root of the cantilever beam by locally reducing the cross-sectional modulus of the cantilever beam when the cap-shaped fiber structure swings and transmits a torque to the cantilever beam.

[0013] Preferably, the flexible connection structure is configured to independently and locally reduce the equivalent stiffness of the four cantilever beam structures by pre-setting the geometric parameters of the flexible connection structure. Preferably, the reduction of the equivalent stiffness compensates for the drop in the natural frequency caused by the increase in the equivalent mass of the cap-shaped fiber structure. Preferably, the reduction of the equivalent stiffness compensates for the drop in the natural frequency caused by the increase in the equivalent mass of the cap-shaped fiber structure.

[0014] Preferably, the reduction of the equivalent stiffness makes the hydrophone improve the sensitivity while regulating the natural frequency of the electric bridge sensitive structure within a preset working bandwidth range, thereby realizing effective decoupling of the sensitivity and the working bandwidth of the hydrophone. Preferably, the flexible connection structure is formed by synchronous etching with the four cantilever beams and the center mass block in a one-time MEMS process.

[0015] Preferably, the flexible connection structure is formed by synchronous etching with the four cantilever beams and the center mass block in a one-time MEMS process.

[0016] A performance optimization method of a cap-shaped fiber MEMS vector hydrophone, comprising the following steps:​​​​ a. A flexible connection structure is arranged at the root of the cantilever beam connecting the sensitive structure of the hydrophone; b. The stress of the cantilever beam is enhanced by the stress concentration effect of the flexible connection structure The sensitivity of the hydrophone is improved; c. The equivalent stiffness of the cantilever beam structure is independently regulated by the geometric parameters of the flexible connection structure to compensate for the decrease in natural frequency caused by the increase in the mass of the capillary The working bandwidth of the hydrophone is regulated within the preset frequency range.

[0017] The present application provides a capillary MEMS vector hydrophone. Has the following beneficial effects: 1. The capillary has a larger sound wave receiving area than the traditional capillary. When subjected to the same size sound pressure signal, the capillary can produce a larger stress on the cantilever beam, thereby causing a larger resistance change in the piezoresistor. Moreover, the hydrophone manufacturing process is simple and mature, the capillary does not need to be integrated twice, ensuring the consistency of the hydrophone. In addition, the hydrophone sensitive structure is processed by MEMS technology, which has the advantage of small size. In addition, the capillary MEMS vector hydrophone also has the advantages of low cost and good low frequency characteristics, and is suitable for small platform integration and low noise target detection scene.

[0018] 2. The present application adopts a capillary structure, is designed based on the principle of bionics and the principle of density matching, significantly increases the receiving area of underwater acoustic signal and the coupling efficiency with water medium, so that the hydrophone can effectively pick up weak sound pressure signal, thereby significantly improving the detection sensitivity of the MEMS vector hydrophone. The capillary structure is rigidly fixed on the center mass block of the MEMS sensitive structure by single integration process, replacing the traditional complex secondary alignment and bonding process, simplifying the manufacturing steps, improving the integration efficiency, and effectively ensuring the consistency and reliability of the hydrophone during batch manufacturing.

[0019] 3. The present application introduces a flexible connection structure, which enhances the sensitivity again through the stress concentration effect. On the other hand, it independently reduces the equivalent stiffness of the four-beam structure by presetting the geometric parameters, effectively compensates for the decrease in natural frequency caused by the increase in the mass of the capillary, and decouples the inherent contradiction between sensitivity and working bandwidth, so that the hydrophone can maintain the required working bandwidth while achieving high sensitivity. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a perspective view of the present application; Figure 2 is a structure diagram of the capillary of the present application; Figure 3This is a circuit diagram of the bridge circuit of the present invention; Figure 4 This is a flowchart of the performance optimization method for the vector hydrophone of the present invention.

[0021] Among them, 1. cap-shaped cilia; 2. central mass block; 3. cantilever beam; 4. square frame. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see the appendix Figure 1 - Appendix Figure 3 This invention provides a cap-shaped microfiber MEMS vector hydrophone, comprising: a cap-shaped microfiber 1 for sensing sound and transmitting vibrations; a central mass block 2 disposed at the bottom of the cap-shaped microfiber 1, with the cap-shaped microfiber 1 located at its top center, the central mass block 2 for receiving and diffusing the vibrations transmitted by the cap-shaped microfiber 1; four cantilever beams 3 fixedly connected to the front, rear, left, and right sides of the central mass block 2 respectively, for receiving the vibrations transmitted by the central mass block 2 and generating deformation; and a square frame 4 disposed outside the four cantilever beams 3, its inner side connected to the four cantilever beams. The end of beam 3 away from the cap-shaped cilia 1 is fixedly connected. The outer middle side of the cap-shaped cilia 1 protrudes into a cap shape. The cap-shaped cilia 1 is made of resin material, and the cantilever beam 3 is made of silicon material. A bridge is arranged on the top of the square frame 4 and the four cantilever beams 3. Two resistors are set on the top bridge of each cantilever beam 3. A flexible connection structure is provided at the root of the connection between the four cantilever beams 3 and the central mass block 2. The flexible connection structure is at least one of the following microstructure forms: narrow waist structure, stress concentration design, or flexible film hinge. The flexible connection structure is used to swing the cap-shaped cilia 1 structure and reduce the torque. When the stress is transferred to cantilever beam 3, it acts as a stress concentration point. The stress at the root of cantilever beam 3 is increased by locally reducing the section modulus of cantilever beam 3. To improve the electrical output sensitivity of the hydrophone, the flexible connection structure, through the preset geometric parameters, is used to independently and locally reduce the equivalent stiffness of the four cantilever beams. stiffness The reduction in mass is compensated by the equivalent mass of the cap-shaped cilia structure. Increased inherent frequency Decrease, equivalent stiffness The reduction in the amount of [something] allows the hydrophone to improve its sensitivity while simultaneously reducing the inherent frequency of the bridge sensitive structure. Within the preset working bandwidth range, the sensitivity of the hydrophone is effectively decoupled from the working bandwidth. The flexible connection structure is formed by simultaneous etching of the four cantilever beams 3 and the central mass block 2 using a one-time MEMS process.

[0024] Specifically, the vector hydrophone is designed based on biomimetic principles, MEMS technology, and the piezoresistive effect. Its sensitive structure consists of three parts: a central mass block 2, four cantilever beams 3, and cap-shaped cilia 1. The cap-shaped cilia 1 are rigidly fixed to the central mass block 2 located at the intersection of the four cantilever beams 3. When a sound signal is transmitted, the cap-shaped cilia 1 will oscillate slightly along the direction of the sound wave, causing the cantilever beams 3 below to deform. This ultimately causes a change in the resistance of the piezoresistive resistors distributed on the cantilever beams 3. These changes can be converted into a DC voltage output through a Wheatstone bridge, realizing the conversion of sound signals into electrical signals. Vector hydrophones pick up sound signals through the joint vibration between the cilia column and the acoustic medium particles. According to the principles of underwater acoustics and vibration, when the average density of the cilia is close to the average density of the medium, the vibration velocity of the cilia is the same as the vibration velocity of the medium particles at their positions, and the phase difference between the two is close to zero. The density of resin is close to that of water, so resin is chosen as the material for the cap-shaped cilia column 1, and silicon is chosen as the material for the cantilever beam 3. The hydrophone is designed based on the piezoresistive effect. The output voltage of the bridge is proportional to the change in the resistance of the piezoresistor. When the stress on the beam is greater, the change in the resistance of the piezoresistor is greater. The sensitivity of the hydrophone can be improved by increasing the stress on the beam. Stress at any point on cantilever beam 3 It can be represented as: in The area for receiving sound signals; External sound pressure; This refers to the force acting horizontally on the cilia. The moment at the center of the intersection of the cantilever beam 3; The height of the center of gravity of the ciliary structure.

[0025] The stress on the cantilever beam 3 is positively correlated with the radius and height of each part of the cilia. Therefore, the sensitivity can be improved by increasing the radius and height of each part of the cilia. The natural frequency of the sensing structure determines the operating bandwidth of the hydrophone. Therefore, a mathematical model is established to study the influence of the sensing structure parameters on the natural frequency. The expression is: ; in: The equivalent mass of the cap-shaped ciliary structure 1; For a four-beam structure Stiffness in the axial direction.

[0026] Increasing the mass of the cilia will limit the working bandwidth. The stress on the beam can be increased by increasing the acoustic wave receiving area of ​​the cilia column, thereby improving the sensitivity. At the same time, the mass of the microstructure should be reduced so that its working bandwidth meets the range of 100Hz to 1000Hz of the ship noise spectrum. The sensitive unit of the hydrophone is fabricated using MEMS technology on an SOI wafer to complete the fabrication of the cantilever beam 3 and the central mass block 2. The manufacturing process mainly includes ion implantation, ohmic contact formation, back silicone etching and front siloxane etching. After the packaged microstructure is soldered onto the PCB board, a dedicated fibrous integration platform is used to integrate the cap-shaped microstructure with the cantilever beam 3.

[0027] Please see the appendix Figure 4 The present invention also provides a performance optimization method for a cap-shaped ciliary MEMS vector hydrophone, comprising the following steps: S101 uses MEMS technology to simultaneously fabricate four cantilever beams 3, a central mass block 2, and a flexible connection structure integrated at the junction of the root of the cantilever beams 3 and the central mass block 2 on an SOI substrate through photolithography and etching processes. S102, a varistor is fabricated in the predetermined stress-sensitive area of ​​the cantilever beam 3 by processes such as ion implantation, and then connected to form a Wheatstone bridge sensing circuit. S103, the cap-shaped fibrous structure 1 is rigidly fixed to the central mass block 2 through a single integration process, completing the integration of the sensitive structure, and then encapsulating and leading out the circuit. S104, when the underwater acoustic pressure signal drives the cap-shaped cilia 1 to swing, the stress concentration effect of the flexible connection structure is used to transfer the torque transmitted by the cilia. Efficiently convert stress at the three roots of the cantilever beam This enhances the signal output of the sensing circuit, thereby improving its sensitivity. S105, by pre-setting the geometric parameters of the flexible connection structure, independently reduces the equivalent stiffness of the four-beam structure. To compensate for the increased mass of cap-shaped cilia 1 The resulting natural frequency This reduces the frequency, thereby improving sensitivity while keeping the operating bandwidth within a preset frequency range.

[0028] S201, Substrate Preparation and First Doping: SO1 wafers are selected as the substrate. The top silicon layer forms the main body of the sensitive structure, the buried oxide layer is used for subsequent release, and the bottom silicon layer provides mechanical support. High concentrations of ions are formed in the predetermined cantilever beam 3 region of the top silicon layer, particularly at the root where strain is greatest and around the flexible connection structure. Type-doped regions are used to fabricate varistors; S202, Photolithography and Top Silicon Patterning: Photoresist is coated on the top silicon layer and photolithography is performed. The length of the cantilever beam 3 is precisely defined using a photomask. ,width ,thickness The half-side length of the central mass block 2 The geometry and location of the flexible connection structure are also considered. The flexible connection structure is designed at the intersection of the four cantilever beams 3 and the central mass block 2. Its form can be a narrow waist or a stress concentration groove. For the narrow waist structure, the photolithographic pattern needs to be applied to the root of the beam to define the width of the cantilever beam 3. Local reduction to For stress concentration groove structures, an etching pattern is designed on the sidewall or surface of the beam. S203, Deep Silicon Etching: Utilizing deep reactive ion etching technology, the patterned top silicon layer is vertically etched until it penetrates the top silicon layer and terminates at the buried oxide layer. This completes the main structure of the four cantilever beams 3 and the central mass block 2 in one operation, simultaneously and precisely forming a flexible connection structure. The flexible connection structure, through the reduction of local geometric dimensions, improves the stiffness of the cantilever beams 3. The process introduces a locally controllable reduction amount. ; S204, Ohmic Contact and Metallization of Varistor: An ohmic contact window is formed above the doped region by photolithography, etching and deposition processes. Then, a metal layer is deposited by processes such as evaporation or sputtering, and electrical connection leads and pads are formed by photolithography. These leads connect the varistor into a Wheatstone bridge sensing circuit. S205, Bottom Silicon Etching and Structure Release: A cavity pattern for releasing the sensitive structure is defined using back-side photolithography. The bottom silicon is etched using DRIE technology until it approaches the buried oxide layer. Subsequently, wet etching is used to remove the buried oxide layer, thereby achieving the mechanical release of the cantilever beam 3, the central mass block 2, and the flexible connection structure. This allows them to vibrate freely in an underwater acoustic field, ensuring high consistency between the geometry, size, and position of the flexible connection structure and the cantilever beam 3 and the central mass block 2, without introducing additional integration steps. The geometric parameters of the flexible connection structure, such as the narrow waist width... Groove depth The amount of local stiffness reduction it provides is directly determined by factors such as temperature and humidity. The key to achieving decoupling between sensitivity and bandwidth lies in the placement of the varistor, specifically in its position on the cantilever beam 3 under stress. The largest area, usually located at the root of the beam or on the side of the beam near the central mass block 2, is any point on the beam when the cantilever beam 3 is subjected to stress and deformation. Stress at the point The resistance of the varistor is affected The change, according to the piezoresistive effect, is the amount of change in resistance. With stress Proportional: ; in, This represents the rate of change of the relative resistance of the varistor. This refers to the longitudinal piezoresistive coefficient; This refers to the lateral piezoresistive coefficient. The stress component is along the direction of the current. This represents the stress component perpendicular to the current direction.

[0029] By connecting varistors into a Wheatstone full-bridge or half-bridge structure, minute changes in resistance can be converted into measurable voltage signals. This enables the electrical output of underwater acoustic signals, with the output voltage being proportional to the change in resistance, and thus related to stress. Proportional to this, therefore, precise fabrication and optimization of the varistor's position, as well as the flexible connection structure, are crucial. The enhancement effect is a specific way to improve the sensitivity of hydrophones.

[0030] S301, Fabrication and Material Selection of Cap-shaped Cilia 1: The cap-shaped cilia 1 structure is made of a material with a density similar to that of water to meet the density matching requirements in underwater acoustics and vibration principles. Commonly used materials are resins, such as photosensitive resins and epoxy resins, whose densities can be adjusted to be close to that of water. The geometry of the cap-shaped cilia 1 includes the lower cylinder of the cilia, the cap cylinder, the upper cylinder of the cilia, and the outer wall of the cap. It is prepared using high-precision 3D printing or precision mold casting techniques to ensure the total height of the cilia. Cilia radius Hat outer wall radius The accuracy of critical dimensions, such as those of the cilia, directly determines the equivalent quality of the cilia. and sound wave receiving area ; S302, Single-stage integration of cap-shaped cilia 1: The prefabricated cap-shaped cilia 1 structure is rigidly fixed to the central mass block 2 of the MEMS sensitive structure through a single-stage integration process. This avoids the complex secondary alignment and bonding required by traditional cilia structures, effectively improving integration efficiency and consistency among batch hydrophone products. The integration process is achieved using a dedicated high-precision cilia integration platform. Through optical alignment and micro-dispensing or thermosetting adhesives, it is ensured that the geometric center of the cap-shaped cilia 1 is highly coincident with the geometric center of the central mass block 2, and the cilia column forms a rigid connection with the central mass block 2. This rigid connection ensures that when the cilia oscillate in the sound field, it can dissipate force... and torque The mass is completely and stably transferred to the central mass block 2 and cantilever beam 3 structure below; S303, Soldering the Sensitive Structure to the PCB: The MEMS sensitive unit chip with integrated cap-shaped fibers 1 is electrically connected and fixed to a PCB board pre-loaded with signal conditioning circuitry via flip-chip bonding or wire bonding. The Wheatstone bridge circuit on the PCB board connects to the leads, amplifying and filtering the weak electrical signal from the varistor on the sensitive structure. S304, Final Packaging of the Hydrophone: To protect sensitive structures from corrosion and impact in the underwater environment, the hydrophone needs to be watertight. The packaging process must ensure that the cap-shaped cilia 1 structure is directly exposed to the underwater sound field to pick up sound signals, while the MEMS chip and circuitry must be completely sealed using insulating and watertight materials. The choice of packaging material must minimize the impact on the sound field and cilia vibration; that is, a material with an acoustic impedance close to that of water should be used as the contact medium to ensure that sound waves can act on the cap-shaped cilia 1 structure without attenuation. Through a single-integration process, the defects of traditional two-integration processes, such as large alignment errors, complex manufacturing, and poor product consistency, are solved. This ensures a rigid and precise connection between the cap-shaped cilia 1 structure and the central mass block 2, laying the structural foundation for the subsequent flexible connection structure to effectively exert its stress enhancement and stiffness control functions. The equivalent mass of the cap-shaped cilia 1 structure... Equivalent center of gravity height and sound wave receiving area The mechanical excitation applied to the cantilever beam 3 was ultimately determined to be the main input to the hydrophone sensitivity.

[0031] S401, Acoustic Excitation and Torque Generation: When an underwater acoustic signal acts on the cap-shaped ciliary structure 1, the ciliary will oscillate slightly along the direction of the acoustic wave. According to the principles of underwater acoustics, the ciliary and the water medium particles vibrate together, and the resultant force on the ciliary... This causes a horizontal force to be generated at its bottom. and torque Torque It is caused by horizontal force Equivalent center of gravity height acting on cilia Produced at: ; in, The moment exerted by the ciliary pendulum motion on the center of the intersection of the cantilever beam 3; This refers to the force acting horizontally on the cilia. The equivalent center of gravity height of the cap-shaped cilia 1 structure.

[0032] S402, Stress Transfer and the Role of Flexible Connection Structures: Force and torque The stress is transferred through the central mass block 2 to the four cantilever beams 3, causing the cantilever beams 3 to bend. The flexible connection structure is integrated at the root of the four cantilever beams 3 as a pre-designed stress concentration point. Compared with the root of a beam with a traditional rigid connection, the local stiffness of this flexible connection structure is lower. Therefore, when subjected to the same moment, the stiffness is reduced. When applied, this region undergoes greater deformation, thus effectively dissipating the torque. This is transformed into high local stress at the root of the cantilever beam; S403, Stress Enhancement Quantification: Stress at any point x on cantilever beam 3 Mainly composed of torque and horizontal force Contribution, for the cantilever beam 3 structure, its stress It can be represented as: ; in, For cantilever beam 3 Stress at the point; The cantilever beam is 3 meters long; The cantilever beam is 3mm wide; The cantilever beam is 3mm thick; Let the length of half of the center mass block be 2.

[0033] The flexible connection structure locally alters the cross-sectional properties of the cantilever beam 3 through its specific geometric design. This local cross-sectional change, particularly the section modulus... The reduction in strain leads to strain on the beam. The stress increases significantly, and consequently, through Hooke's Law, the stress increases significantly. The flexible connection structure reduces the torque. The resulting stress components are enhanced, thus achieving the function of concentrating and amplifying the stress of the cantilever beam 3; S404, Sensitivity Enhancement Achieved by Increasing the Stress at the Location of the Varistor Based on the piezoresistive effect, a larger resistance change of the varistor can be obtained. The electrical output signal of the hydrophone It is the output of the Wheatstone bridge, and Proportional to each other, the flexible connection structure, through the specific feature of stress amplification, achieves the functional generalization of enhancing the signal output of the sensing circuit, directly improving the voltage sensitivity of the hydrophone. This structural design further enhances the hydrophone's ability to detect weak acoustic signals without changing the acoustic receiving area of ​​the cap-shaped cilia.

[0034] S501, Analysis of the contradiction between sensitivity and natural frequency: The sensitivity of the hydrophone and the sound wave receiving area of ​​the cap-shaped cilia 1 Equivalent center of gravity height and equivalent quality Positive correlation; to improve sensitivity, this invention employs a cap-shaped structure to increase... and This inevitably leads to an increase in the equivalent quality of sensitive structures. Increase the natural frequency of the sensitive structure The operating bandwidth of the hydrophone is determined by the following expression: ; in, The intrinsic frequency of the sensitive structure; The equivalent mass of the cap-shaped ciliary structure 1 and the central mass block 2; The equivalent stiffness of the four cantilever beams in the vibration direction is given by the stiffness. With the mass remaining constant The increase will directly lead to the natural frequency The decrease in frequency response limits the operating bandwidth of the hydrophone, potentially causing it to fail to meet the preset frequency range and resulting in reduced quality. The inherent contradiction in the design lies in the conflict between increasing sensitivity and limiting operating bandwidth. S502, Independent Control of Equivalent Stiffness by Flexible Connection Structure: This invention achieves independent control of the equivalent stiffness of the four-beam structure by introducing a flexible connection structure at the root of the cantilever beam 3. The independent reduction of the bending stiffness of the cantilever beam 3 is achieved by locally reducing the cross-sectional dimensions of the cantilever beam 3 without altering other main structural parameters. Local reduction significantly decreases the equivalent stiffness of the entire four-beam structure. Regarding stiffness The regulation of this is independent of the quality of cap-shaped cilia 1. of; S503, Natural Frequency Compensation and Control: By precisely designing the geometric parameters of the flexible connection structure, the stiffness can be adjusted... The decrease, that is, the reduction to This is sufficient to compensate for or even surpass the loss due to the mass of cap-shaped cilia. Increase the natural frequency The resulting decrease in stiffness The reduction in mass can offset The increase in frequency has a negative impact, thus affecting sensitivity by increasing... While improving, the inherent frequency will be Adjust the equivalent stiffness to meet or broaden the preset working bandwidth requirements by utilizing a flexible connection structure. This specific lower-level feature realizes the functional generalization of adjusting the working bandwidth within a preset frequency range; S504, Decoupling of Sensitivity and Bandwidth: Ultimately, this invention achieves independent optimization of sensitivity and operating bandwidth through a flexible connection structure. This means that designers can first maximize sensitivity by adjusting the geometry of the cap-shaped cilia 1, and then adjust the stiffness by finely designing the dimensions of the flexible connection structure. , will the natural frequency By setting the frequency above the target operating bandwidth, the inherent constraint between sensitivity and natural frequency is successfully decoupled, enabling the hydrophone to achieve higher sensitivity while ensuring low-frequency detection capability.

[0035] In summary, by combining the large receiving area design of the cap-shaped cilia 1, the miniaturization advantages of MEMS technology, and the innovative flexible connection structure, this invention not only solves the inherent contradiction between sensitivity and bandwidth in traditional vector hydrophones, but also realizes a new type of high-sensitivity detection device with optimized structure and excellent performance.

Claims

1. A capillary MEMS vector hydrophone characterized by, It comprises: a capillary hair (1) for sensing sound and generating vibration for transmission; a center mass (2) arranged at the bottom of the capillary hair (1) with the capillary hair (1) located at the top center of the center mass (2), the center mass (2) for receiving the vibration transmitted by the capillary hair (1) and diffusing the vibration; four cantilever beams (3) respectively fixedly connected to the front, rear, left and right four sides of the center mass (2) for receiving the vibration transmitted by the center mass (2) and generating deformation; a square frame (4) arranged outside the four cantilever beams (3) with the inner side of the square frame (4) fixedly connected to the end of the four cantilever beams (3) away from the capillary hair (1).

2. The capillary MEMS vector hydrophone of claim 1, wherein, The outer middle side of the capillary hair (1) is protruded in a cap shape, the capillary hair (1) is made of resin material, and the cantilever beam (3) is made of silicon material.

3. The capillary MEMS vector hydrophone of claim 1, wherein, The top of the square frame (4) and the four cantilever beams (3) is arranged with a bridge, and two resistors are arranged on the top bridge of each cantilever beam (3).

4. The capillary MEMS vector hydrophone of claim 1, wherein, The connection root of the four cantilever beams (3) and the center mass (2) is provided with a flexible connection structure.

5. The capillary MEMS vector hydrophone of claim 4, wherein, The flexible connection structure is at least one microstructure form of narrow waist structure, stress concentration design or flexible film hinge.

6. The capillary MEMS vector hydrophone of claim 5, wherein, The flexible connecting structure is used for swinging the capillary (1) structure and transmitting the force moment to the cantilever beam (3) as a stress concentration point , and enhancing the stress of the cantilever beam (3) root by locally reducing the sectional modulus of the cantilever beam (3) , and improving the electrical output sensitivity of the hydrophone.

7. The capillary MEMS vector hydrophone of claim 5, wherein, Said flexible connection structure, through the preset of its geometric parameters, is used to independently and locally reduce the equivalent stiffness of the four cantilever beam (3) structure , the stiffness reduction compensates for the inherent frequency drop caused by the equivalent mass increase of the cap-shaped cilium (1) structure.

8. The capillary MEMS vector hydrophone of claim 7, wherein, The equivalent stiffness The reduced amount of the equivalent stiffness makes the hydrophone improve the sensitivity while reducing the natural frequency of the bridge sensitive structure The regulation is within the preset working bandwidth range, and the effective decoupling of the hydrophone sensitivity and the working bandwidth is realized.

9. The capillary MEMS vector hydrophone of claim 4, wherein, The flexible connection structure is formed by synchronous etching with the four cantilever beams (3) and the center mass (2) in one-time MEMS process.

10. A method for performance optimization of a capillary MEMS vector hydrophone, applied to any of the capillary MEMS vector hydrophones of claims 1-9, characterized in that, It comprises the following steps: a. arranging a flexible connection structure at the cantilever beam (3) connection root of the hydrophone sensitive structure; b. Stress concentration effect of the flexible connecting structure is utilized to enhance the stress of the cantilever beam (3) Improve the sensitivity of the hydrophone; c. The equivalent stiffness of the cantilever beam (3) structure is independently regulated by the geometric parameters of the flexible connecting structure to compensate for the decrease in the natural frequency of the capillary (1) due to the increase in mass of the capillary (1) to regulate the operating bandwidth of the hydrophone within the preset frequency range.

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