Needle hydrophone and method of making same

Abstract

The application provides a needle hydrophone and a preparation method thereof, the hydrophone adopts a piezoelectric ceramic as a core transducing element, when a sound pressure signal is captured at the top end of the hydrophone, the piezoelectric ceramic generates an electric charge due to force, the voltage value generated can be accurately detected through an oscilloscope, then conversion is carried out according to a pre-calibrated sensitivity curve, so that the sound pressure value can be accurately obtained. The new hydrophone has the unique advantages of small size, light weight and high sensitivity, and shows broad application potential in many aspects such as the research and development of high-end ultrasonic equipment in the biomedical field, the real-time monitoring of intracranial pressure of astronauts in the field of aerospace, and the precise detection of underwater fish in the military field, and is expected to bring a new breakthrough to the development of the related field.

Description

Technical Field

[0001] This invention relates to the field of high-precision measuring devices, specifically a needle-type hydrophone and its manufacturing method. Background Technology

[0002] A needle-type hydrophone is an acoustic sensor with needle-shaped geometry. Its core function is to accurately measure sound field parameters in underwater or confined fluid environments by converting sound pressure signals in a water medium into measurable electrical signals. Due to its unique needle-like geometry, this device exhibits irreplaceable advantages in sound field measurements within confined spaces.

[0003] Based on differences in transduction principles, needle hydrophones are mainly divided into two types: piezoelectric and capacitive. Piezoelectric needle hydrophones use piezoelectric ceramics such as PZT (lead zirconate titanate) as the core transduction material. Their advantages lie in high sensitivity and wide bandwidth response (typically 10kHz-10MHz). However, due to the temperature sensitivity of the piezoelectric material, their environmental stability is easily affected by temperature drift. In contrast, capacitive needle hydrophones are manufactured using microelectromechanical systems (MEMS) technology, achieving sound pressure-capacitance conversion through changes in electrode spacing. They offer superior linearity and temperature stability, but their manufacturing cost is 3-5 times higher than that of piezoelectric devices, and they exhibit more noticeable low-frequency noise.

[0004] Based on differences in transduction principles, needle hydrophones are mainly divided into two types: piezoelectric and capacitive. Piezoelectric needle hydrophones use piezoelectric ceramics such as PZT (lead zirconate titanate) as the core transduction material. Their advantages lie in high sensitivity and wide bandwidth response (typically 10kHz-10MHz). However, due to the temperature sensitivity of piezoelectric materials, their environmental stability is easily affected by temperature drift. In contrast, capacitive needle hydrophones are manufactured using microelectromechanical systems (MEMS) technology, achieving sound pressure-capacitance conversion through changes in electrode spacing. They offer superior linearity and temperature stability, but their manufacturing cost is 3-5 times higher than piezoelectric devices, and they exhibit more noticeable low-frequency noise.

[0005] In the rapid development of contemporary acoustics, hydrophones are playing an increasingly prominent role in key fields such as biomedicine, aerospace, and the military, and their importance cannot be underestimated. Zhao Jun et al. used a needle-type hydrophone to perform layer-by-layer scanning in the time and spatial domains to accurately locate the focal point. This method allows for accurate measurement of the sound pressure intensity at the focal point. Huang et al. introduced the interferometric demodulation technology of hydrophone underwater acoustic signals and discussed the application of ultra-thin fiber Bragg grating hydrophones in torpedo guidance. NASA intracranial pressure. To achieve the rapid development of underwater unmanned equipment such as unmanned underwater vehicles (UUVs) and underwater robots, Zhao Bo conducted research on the design and fabrication of MEMS chip structures and packaging, signal conditioning circuit analysis and design, the design and construction of automated hydrophone measurement systems, and comprehensive performance testing of MEMS hydrophones. Therefore, in the field of acoustic detection both domestically and internationally, hydrophones, as key underwater acoustic detection devices, are crucial to scientific research and engineering applications.

[0006] Most current hydrophones are too large to meet the high precision and small size requirements necessary for narrow gap measurements. Furthermore, narrow gap measurements are widely used in cutting-edge fields such as deep-sea research, aerospace, and biomedicine, demanding extremely high precision and size from the measuring equipment. The "PVDF hydrophone RP 70 s" (hereinafter referred to as "RP 70s") from the German company RP Acoustics is a widely used hydrophone that can meet the needs of narrow gap measurements. However, it has two drawbacks: firstly, the effective measurement area is only the tip, which cannot meet the requirements for detecting the inner walls of special micropores; secondly, it uses a PVDF piezoelectric film for detection, which has low sensitivity for high-frequency signals and a limited measurable frequency range. Summary of the Invention

[0007] In order to solve the problems of the prior art, the present invention provides a needle-type hydrophone and its manufacturing method, which has high production efficiency, high integration, low cost, wide detection frequency range, and high detection performance in the high frequency band.

[0008] This invention provides a needle-type hydrophone, comprising a rectangular piezoelectric ceramic sheet. The rectangular piezoelectric ceramic sheet acts as a transducer element, polarizing and generating charge when subjected to sound pressure, serving as the charge source of the hydrophone. The bottom of the piezoelectric ceramic sheet is connected to an internal brass rod via conductive silver paste, with the brass rod serving as the negative electrode of the needle-type hydrophone. The sides of the brass rod are coated with an insulating varnish to isolate the positive and negative electrodes. A layer of conductive silver paste covers the insulating varnish and the outer surface of the piezoelectric ceramic sheet, serving as the positive electrode of the needle-type hydrophone. A signal transmission line is connected to the bottom of the brass rod via a port. The port has a cavity in its center, and the brass rod is inserted into the cavity of the port. The conductive silver paste layer and the port are fixedly connected.

[0009] In a further improvement, the insulating varnish is tightly bonded to the brass rod to form a rectangular cross-section.

[0010] In a further improvement, the port is an SMA port, and the signal transmission line is connected to the port via a spiral interface.

[0011] In a further improvement, a through hole is opened in the center of the port, through which the metal needle in the center of the signal transmission line passes and connects to the brass rod.

[0012] As a further improvement, the outer edge of the conductive silver paste layer is coated with a protective varnish.

[0013] This invention also provides a method for manufacturing a needle-type hydrophone, comprising the following steps:

[0014] 1) Microcutting: Cutting the piezoelectric ceramic sheet into a rectangular structure that fits into the brass rod;

[0015] 2) High-temperature curing: After connecting the rectangular piezoelectric ceramic sheet and the brass rod with conductive silver paste, high-temperature curing is performed. After the conductive silver paste layer is cured, it is fixedly connected to the port.

[0016] 3) Miniature drilling: Several small holes are drilled on the SMA port to clamp and fix the brass rod to the SMA port, so that the signal transmission line is inserted into the small holes of the SMA port, passes through the small holes and connects to the brass rod;

[0017] 4) Step-by-step testing: Check whether the testing equipment is working properly;

[0018] 5) "Encapsulation and conductivity" integration: Conductive silver paste covers the outer surface of the insulating varnish, and a protective varnish is applied to the outer edge of this insulating varnish layer.

[0019] Further improvements, in step 4), the stepwise detection process specifically involves: separating the inner and outer layers of the signal transmission line conductors, and respectively wrapping them around the conductive silver paste on the outside of the brass rod and the bottom end of the brass rod without insulating varnish, forming a closed loop to achieve signal detection.

[0020] Further improvements include the following steps in step 5) for covering the outer surface of the insulating varnish with conductive silver paste:

[0021] 5.1) Using the inverted method, the entire needle hydrophone is inverted before painting, so that the conductive silver paste flows downward to the top of the piezoelectric ceramic sheet under the action of gravity.

[0022] 5.2) Using a rotary spraying method, a brass rod coated with insulating varnish is fixed on a rotating table. The axis of the varnish reservoir is parallel to the axis of the brass rod. The varnish reservoir is aligned with the top of the piezoelectric ceramic. The rotating table is then rotated at a constant speed, while the varnish reservoir moves at a constant speed in a vertical direction until it reaches the top of the SMA port.

[0023] Further improvements include step 2), where the high-temperature curing process is performed using a hot air gun for baking.

[0024] The beneficial effects of this invention are as follows:

[0025] 1) Based on the piezoelectric effect principle, a needle hydrophone was designed using a rectangular piezoelectric ceramic sheet, which improved the high-frequency performance of existing needle hydrophones.

[0026] 2) In the manufacturing process, breakthroughs have been made in five key technologies: micro-cutting technology, high-temperature curing technology, micro-drilling technology, step-by-step testing technology, and "encapsulation and conductivity" integration technology. This has enabled the needle hydrophone to have high production efficiency, high integration, and low cost, giving it a strong market competitiveness.

[0027] 3) When no protective paint is used on the outer layer, the entire outer edge and top of the hydrophone are effective monitoring positions. Compared to existing hydrophones that can only rely on the top for detection, this method has a wider range of applications. When a protective paint is used on the outer layer, the paint provides protection, is waterproof, insulating, and heat-resistant, reducing the impact of environmental factors on the internal structure.

[0028] 4) Needle-type hydrophones are highly sensitive and small in size, making them suitable for experiments in the biomedical field, non-invasive intracranial pressure monitoring for astronauts in orbit in the aerospace field, and underwater torpedo detection in the military field, with good market application prospects. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a diagram of the internal structure of a needle-type hydrophone.

[0031] Figure 2 This is a diagram showing the electron flow of a needle-type hydrophone.

[0032] Figure 3 This is a schematic diagram of a signal detection device.

[0033] Figure 4 The effective value of the signal detected by the RP 70s hydrophone under the same transmitting signal.

[0034] Figure 5 Under the same transmitting signal, the self-made needle-type hydrophone detected the effective value of the signal.

[0035] Figure 6 The values ​​represent the sound pressure levels received by the needle hydrophone at different frequencies.

[0036] Figure 7 Sensitivity curve of a self-made needle hydrophone.

[0037] Figure 8 The sensitivity curve of the RP 70s hydrophone.

[0038] Figure 9 The waveforms of the signals detected by the RP 70s needle hydrophone and the homemade needle hydrophone at 300kHz are displayed on an oscilloscope.

[0039] Figure 10 The waveforms of the signals detected by the RP 70s needle hydrophone and the homemade needle hydrophone at 600kHz are displayed on an oscilloscope.

[0040] Figure 11 The waveforms of the signals detected by the RP 70s needle hydrophone and the homemade needle hydrophone at 1MHz are shown on the oscilloscope.

[0041] Figure 12 The waveforms of the signals detected by the RP 70s needle hydrophone and the homemade needle hydrophone at 1.5MHz are shown on the oscilloscope. Detailed Implementation

[0042] The technical solutions of 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.

[0043] This invention provides a needle-type hydrophone, such as Figure 1 As shown, it includes a rectangular piezoelectric ceramic 1. When the piezoelectric ceramic sheet 1 is subjected to sound pressure, it polarizes and generates charges, serving as the charge source of the hydrophone. The bottom of the piezoelectric ceramic sheet 1 is connected to an internal brass rod 3 via conductive silver paste 2. The brass rod 3 serves as the negative electrode of the needle-type hydrophone. The side of the brass rod 3 is coated with an insulating varnish 4 that isolates the positive and negative electrodes. The insulating varnish 4 and the outer surface of the piezoelectric ceramic sheet 1 are covered with a layer of conductive silver paste 5, which serves as the positive electrode of the needle-type hydrophone. The bottom of the brass rod 3 is connected to a signal transmission line via a port 7. The port 7 has a cavity in the center, and the brass rod is inserted into the cavity of the port. The conductive silver paste layer and the port are fixedly connected.

[0044] In a further improvement, the insulating varnish is tightly bonded to the brass rod to form a rectangular cross-section.

[0045] In a further improvement, the port is an SMA port, and the signal transmission line is connected to the port via a spiral interface.

[0046] In a further improvement, a through hole is opened in the center of the port, through which the metal needle in the center of the signal transmission line passes and connects to the brass rod.

[0047] As a further improvement, the outer edge of the conductive silver paste layer is coated with a protective varnish 6.

[0048] Among them, the piezoelectric ceramic 1 generates charge by polarization when the transducer element is subjected to sound pressure, and serves as the charge source of the hydrophone. It is easy to process and has good high-frequency characteristics.

[0049] Two conductive silver pastes and five conductive silver pastes act as conductors, with strong adhesion and good conductivity.

[0050] Brass rod 3, used as the positive electrode of the hydrophone, has high strength and rigidity, and good conductivity.

[0051] Insulating varnish 4 is used to isolate the positive and negative poles. It has strong adhesion and a small thickness.

[0052] Without the protective varnish 6 on the outer layer, the entire outer edge and top of the hydrophone are effective monitoring positions, making it applicable to a wider range of scenarios compared to existing hydrophones that can only rely on the top for detection. When the protective varnish 6 is used on the outer layer, it provides protection, offering waterproofing, insulation, and high-temperature resistance, reducing the impact of environmental factors on the internal structure.

[0053] Port 7 is used as the negative terminal and is connected by a thread, which ensures good airtightness.

[0054] Rectangular piezoelectric ceramic sheets are easy to process, and piezoelectric ceramic materials have excellent high-frequency characteristics, avoiding the poor high-frequency characteristics of most needle hydrophones made with PVDF films, thus expanding the frequency range of the detected acoustic signals. Silver paste has good conductivity and high chemical stability, resisting oxidation and corrosion, making it suitable for long-term working environments. Simultaneously, silver paste is heat-resistant, maintaining its performance at high operating temperatures. Brass rods have good conductivity, high strength and hardness, and low cost, achieving a good balance between cost and performance. Insulating varnish has good adhesion, tightly bonding with the brass rod to form a rectangular cross-section, improving mechanical strength and providing a certain degree of electromagnetic interference resistance, reducing the influence of external electromagnetic waves on the internal electric field of the needle hydrophone, and improving detection accuracy. The SMA port and signal transmission line (hereinafter referred to as "RF line") are connected by a spiral, ensuring good airtightness and excellent waterproof performance, preventing liquid from entering the port and damaging the instrument.

[0055] When a needle hydrophone is working, the internal electron flow is as follows: Figure 2As shown, when a piezoelectric ceramic is subjected to sound pressure, according to the positive piezoelectric effect, positive and negative charges are generated on its surface, resulting in a potential difference. An electric current is generated in the circuit. Electrons flow out from the negative electrode of the piezoelectric ceramic, through the copper rod and SMA interface, and flow to the external circuit. At the same time, electrons flow in from the external circuit, through the SMA interface and silver paste, and flow into the positive electrode of the piezoelectric ceramic, forming a complete circuit.

[0056] The manufacturing method of the needle hydrophone is as follows:

[0057] 1. Microdissection technology:

[0058] The rectangular piezoelectric ceramic sheets purchased from the manufacturer were irregularly shaped. To ensure a tight fit between the rectangular piezoelectric ceramic sheet and the rectangular cross-section of the brass rod, the cross-section of the piezoelectric ceramic sheet needed to be manually machined into a standard 2mm*2mm rectangle. To achieve this, researchers used an optical microscope and a clamping device to fix the rectangular piezoelectric ceramic sheet onto a stage, simultaneously aligning it with the edge of a length ruler marked with graduations to indicate the dimensions. Then, using a blade, excess material was repeatedly removed through grinding, resulting in a standard rectangular cross-section with sides of 2mm.

[0059] 2. High-temperature curing technology:

[0060] The rectangular piezoelectric ceramic sheet and the brass rod require conductive silver paste for bonding. Due to the uneven application of the conductive silver paste across a 2mm x 2mm cross-section, if the curing time is long, the rectangular piezoelectric ceramic sheet may slip along the cross-section of the brass rod under gravity, reducing the contact area and resulting in a weak connection. Therefore, a hot air gun is used to manually bake the conductive silver paste at a high temperature, rapidly curing it. This enhances adhesion and makes the silver particles in the paste more tightly connected, improving conductivity. It also increases production efficiency.

[0061] 3. Micro-drilling technology:

[0062] The pin-type hydrophone is connected to the RF cable via an SMA port. Internally, the RF cable's metal pin makes electrical contact with the bottom of a brass rod through an internal hole in the SMA port, thus establishing circuit continuity. However, point contact is susceptible to external vibrations, leading to unstable contact or even open circuits. Furthermore, high contact resistance generates heat, affecting current transmission efficiency. To address this, we drilled a 1mm diameter hole in a 2mm section at the bottom of the brass rod. This allows the pin to insert into the hole when the RF cable connects to the SMA port, changing the point contact to a surface contact, which to some extent prevents open circuits and improves detection stability. Simultaneously, to ensure a tight connection between the brass rod and the SMA port, mechanical means were used to clamp them together. Experiments have shown that these two measures prevent open circuits.

[0063] 4. Step-by-step Detection Technology:

[0064] Generally, a sensor can only determine whether it can work properly through signal detection after it is manufactured. However, due to the complex manufacturing process, it is impossible to clearly determine which process has an error. Therefore, the troubleshooting work is extremely difficult, and there is an urgent need for a method to detect whether each step is correct during the manufacturing process. The core components of the needle hydrophone are parts such as the brass rod except for the SMA port. If the core components can detect signals, the product is basically qualified after being manufactured. For this reason, we separate the inner and outer layer conductors of the RF cable and wind them around the conductive silver paste on the outside of the brass rod and the bottom end of the brass rod without insulating paint respectively, so that a closed loop can be formed, and thus signal detection can be achieved. Experiments have proved that the step-by-step detection technology greatly improves the product qualification rate and production efficiency.

[0065] 5. "Encapsulation and Conductivity" Integration Technology

[0066] During the manufacturing process of some models of needle hydrophones, we adopted the "encapsulation and conductivity" integration technology. Briefly speaking, it is to make the conductive silver paste cover the outer surface of the insulating paint, and the conductive silver paste plays the roles of conductivity and encapsulation at the same time. There are two key issues. One is that the conductive silver paste needs to be evenly applied, otherwise it will cause different cross-sectional resistivity and affect the conductivity. The other is that the conductive silver paste cannot flow into the inside of the SMA port, otherwise it will cause the positive and negative poles of the needle hydrophone to conduct and cause a short circuit. For the first problem, we adopted the rotary spraying method. The brass rod coated with insulating paint is fixed on the rotating table, the axis of the paint storage bottle at the paint spraying port is parallel to the axis of the brass rod, the paint spraying port is aligned with the top of the piezoelectric ceramic, and then the rotating table is rotated at a constant speed, and at the same time the paint storage bottle moves in a uniform straight line in the vertical direction until it reaches the top of the SMA port. This can ensure that the conductive silver paste covers the insulating paint surface evenly. For the second problem, we adopted the inversion method, that is, the whole needle hydrophone is inverted before painting, so that the conductive silver paste flows down to the top of the piezoelectric ceramic piece under the action of gravity. On the one hand, it avoids the conductive silver paste flowing into the inside of the SMA port, and on the other hand, it increases the thickness of the conductive silver paste at the top of the piezoelectric ceramic piece to avoid open circuit. Experiments have proved that the above technology makes the needle hydrophone have good sealing while improving the conductivity, and enables the needle hydrophone to show excellent performance.

[0067] The calibration and data detection of the needle hydrophone are as follows:

[0068] I. Signal Detection Device:

[0069] The signal detection device consists of a signal generator, a needle-type hydrophone, an RF cable, a signal amplifier, and an oscilloscope. The detection principle is as follows: The signal generator transmits a signal with a certain voltage amplitude and frequency to a piezoelectric ceramic via a wire. The piezoelectric ceramic converts the electrical signal into a sound pressure signal, which serves as the signal source. The sound wave propagates through the water. Upon receiving the sound pressure signal from the water, the needle-type hydrophone generates an internal current. This current is then amplified by the RF cable and input to the signal amplifier, where its amplitude is increased to 100 times the original signal. The amplified signal is then input to the oscilloscope via the RF cable. The oscilloscope reads the frequency and amplitude of the signal, and the sound pressure level at the tip of the needle-type hydrophone can be calculated based on the sensitivity. A schematic diagram of the detection device is shown below. Figure 3 As shown.

[0070] II. Calibration:

[0071] The PVDF hydrophone RP 70 s (hereinafter referred to as "RP70s") from RP Acoustics, Germany, was used for comparison. The calibration method is as follows:

[0072] 1. Under the same transmitting signal, the effective values ​​of the signals detected by the RP 70s hydrophone and the homemade needle hydrophone were tested respectively, and the results are as follows: Figure 4 and Figure 5 As shown.

[0073] 2. Calculate the sound pressure level at the hydrophone probe at different frequencies using the sensitivity diagram of a standard hydrophone. Figure 6 ).

[0074] 3. The sensitivity of the homemade hydrophone = the effective value of the detected signal / the sound pressure level. Plot the sensitivity curve of the homemade needle-type hydrophone. Figure 7 ), and compared with the sensitivity curve of the RP 70s hydrophone ( Figure 8 In comparison, the overall trends of the two curves are the same.

[0075] III. Comparative Test:

[0076] The waveform of the signal detected by the hydrophone under the same signal amplitude and frequency conditions is used to obtain the signal amplitude and frequency at the receiving end. The stability of the oscilloscope waveform reflects the hydrophone's response characteristics to a specific frequency signal. Figures 9-12 The waveforms on an oscilloscope are the signals detected by the RP 70s needle hydrophone (left) and the homemade needle hydrophone (right) at the same frequency from low frequency to high frequency (300kHz-1.5MHz).

[0077] The test results show that in the low-frequency range, the performance of the self-made needle-type hydrophone is close to that of the RP 70s needle-type hydrophone; while in the high-frequency range, the performance of the self-made needle-type hydrophone surpasses that of the RP 70s needle-type hydrophone. This aligns with the initial design of the needle-type hydrophone, which chose piezoelectric ceramics as the material to improve high-frequency characteristics, thus confirming the theoretical and experimental findings.

[0078] The technical specifications of the German RP 70s needle hydrophone and the self-made needle hydrophone are compared as follows:

[0079] The German RP 70s needle hydrophone: Measurable signal frequency range, 10kHz to 1MHz; operating temperature range, 10℃ to 35℃; maximum measurable sound pressure level, 10bar; spatial resolution 1mm.

[0080] Homemade needle-type hydrophone: Measurable signal frequency range, 100kHz to 2MHz; operating temperature range, 10℃ to 35℃; maximum sound pressure level, 15bar; spatial resolution, 2mm.

[0081] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of the present invention. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple, and relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A needle hydrophone, characterized by: The utility model discloses a needle hydrophone, which comprises a rectangular piezoelectric ceramic, a rectangular piezoelectric ceramic piece is polarized to generate electric charge when being subjected to sound pressure as a transducer element, and the electric charge is a charge source of a hydrophone; the bottom of the piezoelectric ceramic piece is connected with an internal brass rod through conductive silver paste, and the brass rod serves as a negative electrode of the needle hydrophone; the side of the brass rod is coated with insulating paint for isolating the positive and negative electrodes, and a layer of conductive silver paste is covered on the outer surface of the insulating paint and the piezoelectric ceramic piece, which serves as a positive electrode of the needle hydrophone; the bottom of the brass rod is connected with a signal transmission line through a port; the port has a cavity in the center, the brass rod is inserted into the cavity of the port, and the conductive silver paste layer is fixedly connected with the port.

2. The needle hydrophone of claim 1, wherein: The insulating paint is closely attached to the brass rod to form a rectangular cross section.

3. The needle hydrophone of claim 1, wherein: The port is an SMA port, and the signal transmission line is connected with the port through a screw interface.

4. A needle hydrophone according to claim 1 or 3, characterised in that: A through hole is formed in the center of the port, and a metal needle in the center of the signal transmission line passes through the through hole to be connected with the brass rod.

5. The needle hydrophone of claim 1, wherein: The outer edge of the conductive silver paste layer is coated with protective paint.

6. A method for manufacturing a needle hydrophone for use in a needle hydrophone according to any one of claims 1-5, characterized by The utility model discloses a needle hydrophone, which comprises the following steps: 1) Microcutting: cutting a piezoelectric ceramic piece into a rectangular structure that is attached to a brass rod; 2) High-temperature curing: connecting the rectangular piezoelectric ceramic piece and the brass rod through conductive silver paste and then performing high-temperature curing; 3) Micro-drilling: forming a plurality of small holes on the SMA port, clamping and fixedly connecting the brass rod and the SMA port, inserting the signal transmission line into the small holes of the SMA port, and connecting the signal transmission line with the brass rod through the small holes; 4) Step-by-step detection: detecting whether the equipment can work normally; 5) "Packaging and conductive" integration: covering the conductive silver paste on the outer surface of the insulating paint and coating protective paint on the outer edge of the layer of insulating paint.

7. The method of claim 6, wherein: The step-by-step detection process specifically comprises the following steps: separating the inner and outer conductive wires of the signal transmission line, winding the conductive silver paste outside the brass rod and the bottom end of the brass rod without insulating paint around the conductive wires respectively to form a closed loop, and realizing signal detection.

8. The method of claim 6, wherein: The process of covering the conductive silver paste on the outer surface of the insulating paint specifically adopts the following steps: 5.1) Inverting method: inverting the needle hydrophone as a whole before spraying paint to make the conductive silver paste flow downward to the top of the piezoelectric ceramic piece under the action of gravity; 5.2) Rotating spraying method: fixing the brass rod coated with insulating paint on a rotating table, aligning the paint spraying port with the top of the piezoelectric ceramic piece, and then rotating the rotating table at a constant speed while moving the paint storage bottle along the vertical direction at a constant speed until the top of the SMA port is reached.

9. The method of claim 6, wherein: The high-temperature curing process is performed by using a hot air gun to bake.

Images