Second-order vector hydrophone based on electrochemical principle

Abstract

This invention discloses a second-order vector hydrophone based on electrochemical principles, belonging to the field of MEMS sensor and acoustic measurement technology. The hydrophone includes two electrochemical first-order vector hydrophones (100) suspended from a rigid support (200) by springs (300). The distance between the two hydrophones is much smaller than the wavelength of the sound wave. The measurement of the second-order velocity gradient is achieved through a finite difference approximation method. The electrochemical first-order vector hydrophone (100) contains a two-dimensional electrochemical oscillator, with MEMS electrode chips arranged within its flow channel. An iodine-potassium iodide electrolyte system is used, and the vibration signal is converted into an electrical signal through an electrochemical redox reaction. This invention utilizes the electrochemical gain effect and a horn-shaped liquid reservoir structure to enhance sensitivity. Through integrated structural design, it achieves two-dimensional integration, enabling simultaneous point measurement of first-order velocity and second-order velocity gradient. It has advantages such as high directivity, high sensitivity at low frequencies, and miniaturization, making it suitable for underwater low-frequency acoustic signal detection and target localization.

Description

Technical Field

[0001] This invention belongs to the field of MEMS sensor and acoustic measurement technology, specifically relating to a second-order vector hydrophone based on electrochemical principles. Background Technology

[0002] Vector hydrophones, as core sensors for underwater acoustic detection, can simultaneously sense sound pressure and particle velocity vector information, making them crucial for underwater target localization and identification. Current hydrophone technology is evolving towards higher directivity, lower frequency ranges, and higher sensitivity. Based on differences in sensing principles, existing vector hydrophones mainly include piezoelectric, fiber optic, hot-wire, and electrochemical types. Among them, electrochemical vector hydrophones, with their excellent sensitivity in the low-frequency range, demonstrate unique application potential.

[0003] Directivity is a key indicator determining the spatial resolution of a hydrophone. Currently, mainstream first-order vector hydrophones have a theoretical beamwidth of 90°. To obtain a narrower beam and improve directivity, multi-element arrays combined with complex signal processing algorithms are usually required. This approach has inherent limitations such as large system aperture and complex deployment, and its performance improvement is constrained by the basic characteristics of first-order devices.

[0004] Second-order vector hydrophones overcome this limitation in principle, with their pure and hybrid partial-guided types having theoretical beamwidths of 66° and 45° respectively, significantly improving spatial resolution. However, the weak characteristics of high-order sound field signals drastically increase the difficulty of measurement, resulting in slow development of practical second-order vector hydrophones. In existing technologies, second-order hydrophones often employ the finite difference approximation method for measurement. Some researchers have used piezoelectric composite structures to obtain second-order quantities, measured second-order sound pressure gradients based on piezoelectric triple-layer structures, implemented velocity gradient measurements using the hot-wire principle, and made preliminary attempts to measure velocity gradients with electrochemical hydrophones. While these approaches achieve second-order measurements, they also face their own technical bottlenecks: piezoelectric devices perform well at high frequencies, but their sensitivity significantly decreases with decreasing frequency at low frequencies; high-frequency second-order signals place higher demands on device size; the measurement results of second-order quantities obtained through the finite difference approximation have large errors; and piezoelectric hydrophones are difficult to meet low-frequency detection requirements. While hot-wire devices possess the frequency response characteristics of velocity-type devices, their sensitivity in water is relatively low, limiting practical applications. Existing electrochemical velocity gradient hydrophone research uses simple stacked first-order devices, resulting in large sizes and a lack of integrated structural design and optimization, leading to poor performance. Therefore, developing a novel integrated second-order vector hydrophone that combines high directivity and high low-frequency sensitivity is of significant value. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a second-order vector hydrophone based on electrochemical principles. By using two two-dimensional integrated electrochemical first-order vector hydrophones with finite difference approximation, the second-order quantity of velocity gradient is measured, thereby improving the directivity of the hydrophone. Furthermore, the amplification effect of the electrochemical gainer and the horn-shaped structure is utilized to achieve high-sensitivity measurement of low-frequency signals.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A second-order vector hydrophone based on electrochemical principles includes a rigid support, a spring suspension system, and two first-order electrochemical vector hydrophones; wherein,

[0008] The two electrochemical first-order vector hydrophones are symmetrically fixed to both sides of the rigid bracket by the spring suspension system, and the center-to-center distance is much smaller than the minimum wavelength of the sound signal being measured.

[0009] Each of the electrochemical first-order vector hydrophones includes a waterproof housing and a two-dimensional electrochemical oscillator disposed therein, the two-dimensional electrochemical oscillator being used to convert the measured vibration signal into an electrical signal through an electrochemical redox reaction;

[0010] The second-order vector hydrophone acquires the electrical signals output by two electrochemical first-order vector hydrophones and calculates the first-order velocity and second-order velocity gradient at the center point based on the finite difference method.

[0011] The beneficial effects of this invention are as follows:

[0012] Innovative principles and breakthrough performance: The electrochemical transduction principle is applied to a second-order vector hydrophone, which uses the change in ion concentration in the electrolyte to sense vibration, and achieves high-sensitivity measurement in the low-frequency range, overcoming the inherent defects of low-frequency sensitivity attenuation of piezoelectric devices and insufficient sensitivity of hot wire devices.

[0013] Significantly improved directivity: By using the finite difference approximation of two first-order electrochemical hydrophones, the second-order quantity of the velocity gradient is directly obtained, forming a directivity pattern with a narrower beamwidth, which fundamentally improves the ability to resolve the direction of underwater sound sources and the accuracy of positioning.

[0014] High integration and multifunctional measurement: The device is miniaturized by employing an integrated two-dimensional electrochemical oscillator and a compact spring suspension system. This structure can simultaneously and concurrently measure first-order velocity quantities and second-order velocity gradient quantities, and the sensitivity of the first-order velocity channel is twice that of a single first-order hydrophone.

[0015] Enhanced sensitivity: The unique horn-shaped liquid storage cavity structure amplifies weak acoustic signals, effectively improving the overall signal-to-noise ratio and detection capability of the system, providing advantages for the application of hydrophones in complex underwater environments. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of a second-order vector hydrophone based on electrochemical principles according to the present invention;

[0017] Figure 2 This is a schematic diagram illustrating the structural principle of a second-order vector hydrophone based on electrochemical principles according to the present invention.

[0018] Figure 3 This is a three-dimensional schematic diagram of the internal structure of the electrochemical first-order vector hydrophone used in this invention after the external polyurethane encapsulation has been removed.

[0019] Figure 4 This is a structural exploded schematic diagram of the two-dimensional electrochemical oscillator of the present invention;

[0020] Figure 5 This is a cross-sectional view of the single-channel electrochemical oscillator packaging structure of the present invention;

[0021] Figure 6 This is a directional diagram of the speed channel of the present invention;

[0022] Figure 7 This is the directional diagram of the velocity gradient pure partial derivative channel of the present invention;

[0023] Figure 8 This is the directional diagram of the velocity gradient hybrid partial derivative channel of the present invention.

[0024] Figure label:

[0025] 100: Electrochemical first-order vector hydrophone; 200: Rigid support; 300: Spring;

[0026] 101: Sealing groove; 102: Two-dimensional electrochemical oscillator; 103: Aluminum alloy outer wall; 104: Lead wire hole; 105: Fixing hole; 106: Fixing post; 107: Spring suspension hole; 108: Aluminum alloy cover; 109: Oscillator fixing position; 110: Pressure ring; 111: Rubber membrane; 112: Acrylic glass shell; 113: Rubber ring; 114: Flow channel; 115: Electrode chip; 116: Horn-shaped liquid storage chamber; 117: Liquid injection hole. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] The present invention provides a second-order vector hydrophone based on electrochemical principles. Its core lies in the use of two independent first-order vector hydrophone units to achieve high directivity and high sensitivity measurement of the second-order quantity of velocity gradient in the sound field based on the finite difference approximation method.

[0029] refer to Figure 1 This illustration shows the overall three-dimensional structure of the electrochemical second-order vector hydrophone in this embodiment. The hydrophone mainly consists of two electrochemical first-order vector hydrophones 100 (which can be designated as No. 1 and No. 2), a rigid support 200, and springs 300 connecting them. The two electrochemical first-order vector hydrophones 100 are suspended on both sides of the rigid support 200 by the springs 300, with a center-to-center distance between them. This spacing The wavelength must be much smaller than the minimum wavelength within the frequency band of the measured sound signal to ensure that the second-order quantity calculated by the finite difference method accurately represents the actual second-order quantity at the center point. In this embodiment, the rigid support 200 is a hollow cylindrical structure, connecting two rings via four equal-length pillars. The length of the pillars determines the spacing between the two electrochemical first-order vector hydrophones 100. The rings have holes for suspending springs 300. The electrochemical first-order vector hydrophones 100 are suspended from the rings by the springs 300, achieving concentricity between the rings and the electrochemical first-order vector hydrophones 100, and coaxiality between the two electrochemical first-order vector hydrophones 100. All holes in the figure are for fixing the second-order vector hydrophones during subsequent testing and use. Due to the spring suspension system, the two electrochemical first-order vector hydrophones 100 can move independently, each responding to the velocity of the mass point at its center. The electrochemical first-order vector hydrophone 100 used in this embodiment is completely encased in polyurethane for waterproof sealing; the inner shell is made of aluminum alloy for mounting and fixing the sensitive element. The density of the entire electrochemical first-order vector hydrophone 100 is the same as that of water, thus achieving a vibration velocity of the device equal to the velocity of the water particle at the center point.

[0030] Furthermore, the structure of the rigid support 200 is not limited to a hollow cylinder; any structure that enables the two electrochemical first-order vector hydrophones 100 to maintain a distance and vibrate independently is applicable.

[0031] The shape of the electrochemical first-order vector hydrophone 100 is not limited to a cylindrical shape; it can also be spherical, capsule-shaped, or other shapes suitable for underwater acoustic measurement. Furthermore, it is not limited to two-dimensional models; one-dimensional or three-dimensional first-order vector hydrophones, and even sound pressure hydrophones, can be combined as basic units.

[0032] Figure 2The measurement principle of this invention is demonstrated. The electrochemical first-order vector hydrophone 100 used in the electrochemical second-order vector hydrophone constituting this embodiment is a two-dimensional first-order vector hydrophone, capable of simultaneously measuring the velocity signals of sound particles in both the x and y directions. In practical use, the spacing... When the wavelength is much smaller than the sound signal wavelength, the center point can be measured simultaneously using different calculation methods. The first-order and second-order quantities at the point are velocity and velocity gradient, respectively. Depending on their mathematical form, the second-order quantities can be further divided into pure partial derivatives of the velocity gradient and mixed partial derivatives of the velocity gradient. The approximate calculation methods for these three channels are as follows:

[0033] Speed ​​Channel:

[0034] , ;

[0035] Velocity gradient pure partial derivative channel:

[0036] ;

[0037] Velocity gradient mixed partial derivative channel:

[0038] ;

[0039] in, The velocity in the x-direction is measured by the first-order two-dimensional vector hydrophone (No. 1). The x-direction velocity measured by the second two-dimensional first-order vector hydrophone. The velocity in the y-direction is measured by the first-order two-dimensional vector hydrophone (No. 1). The velocity in the y-direction is measured by the second two-dimensional first-order vector hydrophone. The velocity in the x-direction is measured by a second-order vector hydrophone. The velocity in the y-direction is measured by a second-order vector hydrophone. For the difference interval, The pure partial derivative of the velocity gradient measured by a second-order vector hydrophone. The mixed partial derivative of the velocity gradient measured by a second-order vector hydrophone.

[0040] Figure 3This is a three-dimensional schematic diagram of the internal structure of the electrochemical first-order vector hydrophone 100 after removing the polyurethane. It features a waterproof and sealed design, with the outer shell consisting of an aluminum alloy outer wall 103 and an aluminum alloy cover 108 fastened together with screws at fixing holes 105. A rubber sealing ring is placed in the sealing groove 101 of the aluminum alloy cover 108 to ensure the waterproofness of the shell. The core sensing element—a two-dimensional electrochemical oscillator 102—is mounted and fixed to the fixing post 106 of the aluminum alloy cover 108 via an oscillator fixing position 109. The aluminum alloy outer wall 103 encloses the two-dimensional electrochemical oscillator 102, and the electrical signal obtained by the two-dimensional electrochemical oscillator 102 is led out to an external data acquisition system through the lead hole 104 on the aluminum alloy outer wall 103. The density of the entire electrochemical first-order vector hydrophone 100 is precisely designed to be the same as or close to the density of water, thereby ensuring that its vibration velocity accurately reflects the movement velocity of water particles at the center of mass of the device. The spring suspension holes 107 on both sides of the aluminum alloy outer wall 103 are used to connect the spring 300, so as to achieve a flexible connection with the rigid bracket 200.

[0041] Figure 4 and Figure 5 A schematic diagram of a two-dimensional electrochemical oscillator 102 is shown. The two-dimensional electrochemical oscillator 102 is an integrated orthogonal vibration-sensitive device filled with electrolyte. The integrated orthogonality means that the two-dimensional electrochemical oscillator 102 includes orthogonally placed left and right units, while also referencing… Figure 3 In the left unit, two plexiglass shells 112 form a complete electrolyte chamber. Each plexiglass shell 112 has a flow channel 114 inside. A rubber ring 113 is mounted on the contact surface of each of the two flow channels 114. An electrode chip 115 is fixed between the two rubber rings 113, enabling one-dimensional acoustic signal measurement. The right unit has the same structure as the left unit, but is orthogonally placed, allowing for the measurement of orthogonal signals. and It is sensitive to directional acoustic signals. The electrode chip 115 is a silicon-based chip fabricated using MEMS technology, containing thousands of... The flow holes, with Ti / Pt metal (or other materials with excellent conductivity and corrosion resistance) distributed on the silicon surface and inner sidewalls of the holes, serve as electrodes for the reaction in the electrolyte solution system. Each plexiglass housing 112 has a funnel-shaped liquid reservoir 116 on its outer side (see...). Figure 5The electrolyte acts as a sensitizer, amplifying external vibration signals to improve the device's sensitivity. The electrolyte is injected through the injection hole 117, ensuring no air bubbles are present in the cavity. In this embodiment, the electrolyte solution system consists of iodine and potassium iodide, capable of undergoing a redox reaction (other systems capable of reversible redox reactions, such as bromine-bromide, ferricyanide-ferrocyanide, etc., can be substituted). When there is no external signal, the reaction within the electrolyte is in equilibrium. When external vibration is transmitted, the rubber membrane 111, located below the pressure ring 110 and outside the plexiglass shell 112, picks up the vibration signal and converts it into a change in the ion concentration distribution within the horn-shaped reservoir 116 and flow channel 114. At this point, the equilibrium state of the reaction is broken, and an electrical signal output proportional to the external vibration speed is generated on the electrode chip 115. This signal is led out through the lead hole 104 on the aluminum alloy outer wall 103 to an external data acquisition system, thereby achieving vibration speed measurement.

[0042] Figure 6 , Figure 7 , Figure 8 The directivity patterns of three channels measured by the hydrophone of this invention are shown: the directivity patterns of the velocity channel, the velocity gradient pure partial derivative channel, and the velocity gradient mixed partial derivative channel. It can be seen from the figure that the 3dB beamwidth of the velocity gradient pure partial derivative channel and the velocity gradient mixed partial derivative channel is significantly narrower than that of the velocity channel, indicating that the second-order vector hydrophone has higher directivity than the first-order vector hydrophone.

[0043] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A second-order vector hydrophone based on electrochemical principles, characterized in that, It includes a rigid support, a spring suspension system, and two electrochemical first-order vector hydrophones; among which, The two electrochemical first-order vector hydrophones are symmetrically fixed to both sides of the rigid bracket by the spring suspension system, and the center distance is much smaller than the minimum wavelength of the sound signal being measured, so as to ensure that the second-order quantity calculated by the finite difference method can accurately represent the actual second-order quantity at the center point. Each of the aforementioned electrochemical first-order vector hydrophones includes a waterproof housing and an integrated two-dimensional electrochemical oscillator disposed therein. The two-dimensional electrochemical oscillator is used to convert the measured vibration signal into an electrical signal through an electrochemical redox reaction. The two-dimensional electrochemical oscillator is an integrated orthogonal vibration-sensitive device filled with electrolyte, comprising a left-side unit and a right-side unit with identical structures but orthogonally placed in the same cavity, sensitive to acoustic signals in the orthogonal x and y directions respectively, to achieve the concurrent measurement of acoustic velocity signals in two orthogonal directions. Each of the left-side and right-side units includes: A pair of oppositely arranged acrylic glass shells, each with a flow channel on the inner side and a funnel-shaped liquid storage cavity on the outer side; An electrode chip is disposed between the flow channel end faces of the two organic glass shells, and the electrode chip is sealed and fixed to the two flow channel end faces by two rubber rings respectively; And a rubber membrane covering the outside of the funnel-shaped liquid storage cavity; The second-order vector hydrophone acquires the electrical signals output by two electrochemical first-order vector hydrophones and calculates the first-order velocity and second-order velocity gradient at the center point based on the finite difference method. The electrochemical first-order vector hydrophone is a co-vibration sensor, whose overall density is the same as or similar to that of water. When an external vibration is transmitted, the rubber membrane located outside the plexiglass shell picks up the vibration signal and converts it into a change in the ion concentration distribution in the horn-shaped reservoir and the internal flow channel electrolyte. This causes an electrical signal output on the electrode chip that is proportional to the external vibration speed, thereby realizing the measurement of vibration speed.

2. The second-order vector hydrophone based on electrochemical principles according to claim 1, characterized in that, The rigid support is a hollow cylindrical structure, including two rings and multiple equal-length support columns connecting the two rings. The rings are provided with holes for suspending the spring suspension system.

3. A second-order vector hydrophone based on electrochemical principles according to claim 2, characterized in that, The length of the support determines the spacing between the two electrochemical first-order vector hydrophones.

4. A second-order vector hydrophone based on electrochemical principles according to claim 1, characterized in that, The spring suspension system includes multiple springs, with a rigid bracket and an electrochemical first-order vector hydrophone connected to each end of the spring, enabling two electrochemical first-order vector hydrophones to vibrate independently.

5. A second-order vector hydrophone based on electrochemical principles according to claim 1, characterized in that, The outer shell of the electrochemical first-order vector hydrophone is composed of an aluminum alloy outer wall and aluminum alloy caps at both ends. The aluminum alloy outer wall encloses a two-dimensional electrochemical oscillator, and the electrical signal obtained by the two-dimensional electrochemical oscillator is led out to an external data acquisition system through the lead hole on the aluminum alloy outer wall.

6. A second-order vector hydrophone based on electrochemical principles according to claim 5, characterized in that, The electrode chip is a silicon-based chip fabricated using MEMS technology. It contains thousands of μm-level flow holes, and the silicon surface and the inner sidewalls of the holes are covered with electrodes that act as the electrolyte solute system for reaction.

7. A second-order vector hydrophone based on electrochemical principles according to claim 6, characterized in that, The electrolyte is an electrolyte solution capable of undergoing a reversible redox reaction.

8. A second-order vector hydrophone based on electrochemical principles according to claim 1, characterized in that, The first-order velocity quantity is obtained by adding the corresponding directional velocity components measured by two first-order vector hydrophones; the second-order velocity gradient quantity is obtained by calculating the ratio of the difference between the corresponding directional velocity components measured by the two first-order vector hydrophones to the center distance.

Images