Underwater sound pressure sensor, sensor preparation method and underwater sound monitoring device

Abstract

The invention discloses an underwater sound pressure sensor, a sensor preparation method and an underwater sound monitoring device, and relates to the technical field of underwater sound monitoring. The underwater acoustic pressure sensor comprises an upper-layer plate electrode, a double-sided microstructure dielectric layer and a lower-layer plate electrode which are sequentially arranged from top to bottom, and the upper-layer plate electrode and the lower-layer plate electrode are made of 7wt% carbon nanotube-polydimethylsilane composite materials. The double-sided microstructure dielectric layer is made of a 2wt% carbon nanotube-polydimethylsilane composite material, and convex or concave structures are distributed on the upper surface and the lower surface of the double-sided microstructure. The flexible capacitive pressure sensor is prepared on the basis of the CNTs-PDMS composite material, high sensitivity, fast response and broadband monitoring are achieved through the specific structural design and the preparation method, impedance matching with water sound is achieved, the underwater sound monitoring capacity is improved, and the flexible capacitive pressure sensor has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater acoustic monitoring, and in particular to an underwater acoustic pressure sensor, a sensor preparation method, and an underwater acoustic monitoring device. Background Art

[0002] Sound is a mechanical wave generated by the vibration of an object, propagating through a medium. When sound waves reach a surface, they cause tiny changes in the local pressure. Flexible pressure sensors can accurately capture these minute pressure changes and monitor sound by converting the mechanical signal into an electrical one. This technology, with its excellent flexibility and reliability, has been widely applied in various fields.

[0003] The existing underwater sound monitoring equipment has the following main problems:

[0004] Complex structural design: The device has numerous internal components and a complex structure, which not only increases the difficulty of manufacturing and maintenance, but may also cause signal loss during transmission, affecting monitoring accuracy and stability.

[0005] Metal Materials: Traditional underwater sound monitoring equipment often utilizes metal materials, especially for key components. However, these materials exhibit a significant impedance mismatch between acoustic properties and water. The high density and high speed of sound in metal materials lead to inefficient sound wave transmission between the sensor and the water, resulting in signal attenuation and reduced response sensitivity.

[0006] Low sensitivity: Due to limitations in sensor materials and structure, the device's response to underwater sound is insufficient, making it difficult to accurately capture weak sound signals, especially low-frequency underwater sounds. In complex underwater environments, where interference factors such as background noise and multipath effects are present, the device's ability to resist interference is limited, further reducing monitoring accuracy.

[0007] These problems severely limit the application effect of existing underwater sound monitoring equipment. There is an urgent need to overcome these technical bottlenecks through innovative design and material optimization to improve the performance and practical application value of the equipment. Summary of the Invention

[0008] In light of the shortcomings of existing technologies, the present invention provides an underwater acoustic pressure sensor, a sensor preparation method, and an underwater acoustic monitoring device. This flexible capacitive pressure sensor, fabricated from a CNTs-PDMS composite material, achieves high sensitivity, fast response, and broadband monitoring through a specific structural design and preparation method. Furthermore, it matches the acoustic impedance of the water, enhancing underwater sound monitoring capabilities and possessing broad application prospects.

[0009] The technical means adopted in the present invention are as follows:

[0010] On the one hand, the present invention provides an underwater acoustic pressure sensor, comprising an upper flat electrode, a double-sided microstructured dielectric layer, and a lower flat electrode arranged in sequence from top to bottom, wherein the upper flat electrode and the lower flat electrode are made of a 7wt% carbon nanotube-polydimethylsilane composite material, and the double-sided microstructured dielectric layer is made of a 2wt% carbon nanotube-polydimethylsilane composite material, wherein the upper and lower surfaces of the double-sided microstructure are distributed with protrusions or depressions.

[0011] Furthermore, electrode lead-out terminals are provided at the edge of the upper surface of the upper flat electrode and the edge of the lower surface of the lower flat electrode.

[0012] Furthermore, the mass ratio of CNTs to PDMS in the upper flat electrode and the lower flat electrode is 7:100, and the thickness is 50 μm.

[0013] Furthermore, the mass ratio of CNTs to PDMS in the double-sided microstructured dielectric layer is 1:50, and the thickness is 500 μm.

[0014] In one aspect, the present invention further provides a sensor preparation method for preparing the above-mentioned underwater acoustic pressure sensor, comprising the following steps:

[0015] respectively preparing a flat electrode pre-solution and a double-sided microstructure dielectric layer pre-solution;

[0016] Manufacturing a double-sided microstructured dielectric layer based on a double-sided microstructured dielectric layer precursor solution;

[0017] Making a flat electrode based on a flat electrode pre-solution;

[0018] The fabricated double-sided microstructured dielectric layer and the flat electrode are sequentially subjected to heating treatment and immersion swelling treatment;

[0019] The processed flat electrode and the double-sided microstructured dielectric layer are cut into a preset shape, stacked and assembled in the order of flat electrode-double-sided microstructured dielectric layer-flat electrode, and pre-pressed to bond the electrode and the dielectric layer into one.

[0020] Furthermore, the flat electrode pre-solution is a 7 wt % CNTs-PDMS isopropanol solution, which is prepared by dissolving CNTs, PDMS, and a curing agent in isopropanol.

[0021] Furthermore, the double-sided microstructure dielectric layer pre-solution is a 2 wt % CNTs-PDMS isopropyl alcohol solution, which is prepared by dissolving CNTs, PDMS, and a curing agent in isopropyl alcohol.

[0022] Another aspect of the present invention provides an underwater acoustic monitoring device for performing underwater acoustic monitoring based on the above-mentioned sensor.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The underwater acoustic sensor proposed in this application adopts a double-sided microstructured dielectric layer design and a heating-immersion bonding process to bond the polymer flat electrode to the polymer dielectric layer, thereby reducing the mutual displacement and energy dissipation between the electrode and the dielectric layer during operation of the device, thereby significantly improving the detection range, response time and sensitivity.

[0025] 2. The underwater acoustic sensor proposed in this application is made of a carbon nanotube-polydimethylsilane (CNTs-PDMS) composite material, whose acoustic impedance characteristics are close to those of water, and can significantly enhance the underwater acoustic response capability.

[0026] 3. Compared with the non-microstructured dielectric layer and non-adhesive connection method, the underwater acoustic sensor in this application significantly improves the pressure detection range and response time of the sensor by manufacturing a microstructure in the dielectric layer and using a dielectric layer boss and a polymer electrode bonding structure of the same material.

[0027] 4. The underwater acoustic sensor material in this application does not contain any metal components, which makes it have an acoustic impedance characteristic closer to that of water compared with other underwater sound monitoring devices, thereby significantly improving the underwater sound response capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 Schematic diagram of the structure of the underwater acoustic pressure sensor in an embodiment of the present invention.

[0030] Figure 2 Schematic diagram of the principle of the underwater acoustic pressure sensor when no force is applied in an embodiment of the present invention.

[0031] Figure 3 Schematic diagram of the principle of the underwater acoustic pressure sensor under force in an embodiment of the present invention.

[0032] Figure 4 Schematic diagram of the equivalent circuit of the underwater acoustic pressure sensor in an embodiment of the present invention.

[0033] Figure 5 Schematic diagram of the test system structure of the underwater acoustic pressure sensor in an embodiment of the present invention.

[0034] Figure 6Schematic diagram of the sensitivity change of the underwater acoustic pressure sensor within a pressure range of 600 kPa in an embodiment of the present invention.

[0035] Figure 7 Schematic diagram of the response of the underwater acoustic pressure sensor to underwater sound in an embodiment of the present invention.

[0036] Figure 8 Schematic diagram of the structure of an underwater acoustic monitoring device in an embodiment of the present invention.

[0037] In the figure: 1. upper flat electrode; 2. double-sided microstructured dielectric layer; 3. lower flat electrode; 4. electrode lead-out terminal of the upper flat electrode; 5. electrode lead-out terminal of the lower flat electrode. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0039] Example 1

[0040] like Figure 1 As shown, the present invention provides an underwater acoustic pressure sensor comprising, arranged in order from top to bottom, an upper flat electrode, a double-sided microstructured dielectric layer, and a lower flat electrode. The upper and lower flat electrodes are made of a 7wt% carbon nanotube-polydimethylsilane composite material, and the double-sided microstructured dielectric layer is made of a 2wt% carbon nanotube-polydimethylsilane composite material. The upper and lower surfaces of the double-sided microstructure are distributed with protrusions or depressions. The sensor comprises upper and lower flat electrodes 1, 3, and a double-sided microstructured dielectric layer 2 in between. The flat electrodes are made of a 7wt% carbon nanotube-polydimethylsilane (CNTs-PDMS) composite material, and the double-sided microstructured dielectric layer is made of a 2wt% carbon nanotube-polydimethylsilane (CNTs-PDMS) composite material. The upper and lower flat electrodes and the double-sided microstructured dielectric layer together form a capacitive structure. Copper tape 4, 5 is affixed to either side of the flat electrodes to serve as electrode lead terminals.

[0041] like Figure 2-3As shown, the sensing mechanism of a pressure sensor primarily involves the following: When the sensor is subjected to applied pressure, the relative distance between the dielectric layers decreases, while the contact surface area increases, causing a change in capacitance. This capacitance change reflects the magnitude of the pressure applied to the device. To further enhance the sensor's sensitivity and detection range, three improvement strategies are proposed. First, an innovative bonding structure is employed, in which dielectric layer protrusions are bonded to polymer electrodes made of the same material. This structure allows for tight adhesion between the flat electrode and the raised areas of the microstructured dielectric layer. Compared to traditional non-bonded connection methods, this bonding structure reduces the sensor's lateral displacement and frictional losses under pressure, significantly reducing energy loss during deformation, improving response speed, and expanding the frequency response range, achieving a broadband effect. Second, by forming a microstructured dielectric layer on the surface of the dielectric layer, the sensor's dielectric layer deformation under pressure is effectively increased. The microstructured dielectric layer forms tiny protrusions or depressions on the dielectric layer's surface, increasing the effective contact area between the electrodes. When pressure is applied, these microstructures make the change in the distance between the plates more significant, or the increase in the contact area more obvious, resulting in a greater change in capacitance. Finally, by doping CNTs (carbon nanotubes) into the dielectric layer material, when the volume fraction of the doped conductive particles approaches the threshold, the dielectric constant of the mixture will increase significantly. When the sensor is deformed by pressure, a tiny capacitive structure C0 is formed between the conductive particles. Through the above three mechanisms, the capacitance change value during the deformation process can be effectively increased, thereby significantly improving the sensitivity of the sensor and expanding its pressure detection range to achieve a broadband effect.

[0042] like Figure 4 As shown in the equivalent circuit diagram of the pressure sensor, the dielectric layer's protrusions bonded to the polymer electrodes made of the same material form multiple parallel-connected variable capacitance structures with the carbon nanotubes in the dielectric layer. This variable capacitance structure is connected in parallel with the variable capacitance structure using air as the dielectric layer, ultimately forming the sensor's overall equivalent variable capacitance structure.

[0043] By building Figure 5The sensor performance testing platform shown in the figure was used to conduct sensitivity experiments on the pressure sensing performance parameters of the sensor. Specifically, the terminals of the LCR tester were connected to the copper wires on both sides of the sensor. The LCR tester was set to CP-D measurement mode, with an operating frequency of 1 kHz and an applied voltage of 1 V, and was calibrated. The experimental system consisted of a digital pressure gauge and an LCR tester (Aglient 4263B) for collecting, analyzing, and displaying sensor performance data. The digital pressure gauge provided the applied pressure required for pressure sensor testing, with a resolution of 0.1 N. The LCR tester monitored and displayed the sensor's capacitance changes in real time, also using CP-D mode, a frequency of 1 kHz, and a voltage of 1 V. The instrument was also calibrated. To ensure experimental accuracy, a small acrylic plate measuring 1.6 cm × 1.1 cm was attached to the bottom surface of the digital pressure gauge using hot melt adhesive. This plate served as the force application area, completely overlapping the force-bearing area on the sensor surface. The pressure-bearing area of ​​the force application area was 1.76 cm. 2 , that is 0.00176m 2 According to the pressure formula P = F / S (pressure is equal to the ratio of pressure to pressure area), the sensing performance of the sensor is tested by applying pressure. Figure 6 As shown, the sensitivity of the sensor shows excellent performance characteristics in different pressure ranges. Specifically, in the low pressure range (0-50kPa), the sensitivity of the sensor is 0.00977kPa -1 ; Medium pressure range (50-200kPa) sensitivity is 0.0124kPa -1 ; High pressure range (200-500kPa) sensitivity is 0.00607kPa -1 Notably, by fabricating a dielectric layer with a protruding platform bonded to a polymer electrode made of the same material, the sensor maintains good sensitivity across a wide pressure range of 0-500kPa. Compared to similar sensors reported in the literature, this flexible pressure sensor has the largest detection range and exhibits significant performance advantages.

[0044] Sound is a mechanical wave generated by the vibration of an object, propagating as a wave through a medium. When a sound wave reaches the sensor surface, it causes a slight change in the local pressure on the sensor surface. When the sensor receives a sound signal underwater, the plate electrode vibrates slightly. This vibration is transmitted to the dielectric layer, causing it to vibrate, resulting in a change in capacitance.

[0045] The principle of underwater sound monitoring of the underwater acoustic pressure sensor of the present invention is as follows Figure 7As shown, sound is a mechanical wave generated by the vibration of an object and can propagate as a wave through a medium. When the sound wave propagates to the sensor surface, it causes a slight change in the local pressure on the sensor surface. When the sensor receives a sound signal underwater, the flat electrode vibrates slightly. This vibration is transmitted to the dielectric layer, causing it to vibrate, resulting in a change in capacitance. This change in capacitance is output as a signal and received by the terminal device, enabling underwater sound detection. In acoustic devices, matching the impedance of different media can reduce sound wave reflection at the interface and improve the efficiency of sound energy transmission. The sensor is primarily composed of polydimethylsilane (PDMS), with an acoustic impedance of 970,000 Rayl, which is close to the water acoustic impedance of 1.48×10^6 Rayl. Compared to hydrophones made of ceramic or metal materials, PDMS's matching properties with water acoustic impedance can be used as the primary sensor material to reduce acoustic energy loss and significantly improve underwater acoustic response.

[0046] As a further improvement of the present invention, the mass ratio of CNTs to PDMS in the flat electrode is 7:100, and the thickness is 50 μm to obtain the best mechanical conduction ability and electrical conductivity.

[0047] As a further improvement of the present invention, the microstructured dielectric layer is made of sandpaper with a roughness of 500Cw, the mass ratio of CNTs to PDMS is 1:50, and the thickness is 500μm to achieve the best sensitivity and detection range.

[0048] Example 2

[0049] This embodiment provides a method for preparing an underwater acoustic pressure sensor as given in Example 1. The uncured 2wt% CNTs-PDMS material has a certain fluidity and plasticity. In this embodiment, a double-sided microstructure can be realized on the dielectric layer on sandpaper with a roughness of 500Cw by means of inverted molding. Microstructures are made on both sides of the dielectric layer. The microstructured dielectric layer increases the effective contact area between the plates by forming tiny protrusions or depressions on the surface of the dielectric layer. When pressure is applied, these microstructures make the change in the distance between the plates more significant, or the increase in the contact area more obvious. Compared with a dielectric layer without a microstructure, a sensor with a microstructured dielectric layer has a greater capacitance change and higher sensitivity under the same pressure.

[0050] In order to prepare the bonding structure of the dielectric layer boss and the polymer electrode of the same material, the manufacturing process is as follows: soak the electrode and the dielectric layer in an 11wt% PDMS-isopropyl alcohol solution (5g PDMS, 0.5g curing agent, 50g isopropyl alcohol) and place them at room temperature for 6 hours. Cut the flat electrode and the microstructured dielectric layer into a rectangular shape of 11mm×16mm. Stack them in the order of flat electrode-microstructured dielectric layer-flat electrode, place them in an oven, apply 10kPa pressure on the upper end, and heat them at 80℃ for 2 hours (immersion swelling-heating process). Using this process, the flat electrode and the protrusion of the microstructured dielectric layer can be tightly bonded to form a variable capacitance structure. Compared with the traditional non-bonding connection method, the bonding structure of the dielectric layer boss and the polymer electrode of the same material effectively reduces the horizontal displacement and friction loss of the sensor when under pressure, significantly reduces the energy loss during deformation, improves the response speed, expands the frequency response range, and achieves a broadband effect. The preparation method of the sensor in this embodiment specifically includes the following steps.

[0051] Step 1: Solution preparation

[0052] Two corresponding solutions are prepared respectively: a planar electrode pre-solution and a microstructured dielectric layer solution.

[0053] 1. Flat electrode pre-solution: Weigh CNTs (0.77 g), PDMS (10 g), and curing agent (dimethylmethylhydrogensiloxane) (1 g), and dissolve them in isopropanol (100 ml) to prepare a 7 wt % CNTs-PDMS isopropanol solution.

[0054] 2. Microstructured dielectric layer solution: CNTs (0.22 g), PDMS (10 g), and curing agent (1 g) were weighed and dissolved in isopropanol (100 ml) to prepare a 2 wt % CNTs-PDMS isopropanol solution.

[0055] The two solutions were ultrasonicated for 1 hour to remove bubbles, and then allowed to stand at room temperature to remove isopropyl alcohol.

[0056] Step 2: Fabrication of microstructured dielectric layer

[0057] 1. Stick 500Cw roughness sandpaper on the surface of the glass culture dish and the surface of the slide respectively.

[0058] 2. Pour the microstructured dielectric layer solution into a glass culture dish and spin coat it using a spin coater. Set the rotation speed to 1500 r / min to ensure that the dielectric layer thickness is about 500 μm.

[0059] 3. Place a 500 μm spacer in a glass dish and cover it with a glass slide covered with sandpaper.

[0060] Step 3: Flat electrode fabrication

[0061] 1. Pour the flat electrode pre-solution into a mold with an area of ​​1.4 cm × 4 cm and a thickness of 50 μm.

[0062] 2. Use a glass slide to spread the solution evenly and cover with another glass slide to make the surface flat.

[0063] Step 4: Heat treatment

[0064] The mold of the electrode and dielectric layer was placed in an oven and heated at 80° C. for 2 hours. After heating, the electrode and dielectric layer were removed from the mold.

[0065] Step 5: Soaking and swelling

[0066] The electrodes and the dielectric layer were immersed in an 11 wt % PDMS-isopropyl alcohol solution (5 g of PDMS, 0.5 g of a curing agent, and 50 g of isopropyl alcohol) and placed at room temperature for 6 hours.

[0067] Step 6: Assembly

[0068] The flat electrode and microstructured dielectric layer were cut into 11mm×16mm rectangular shapes. The three-layer capacitor structure was stacked in the order of flat electrode-microstructured dielectric layer-flat electrode, placed in an oven, and a pressure of 10kPa was applied to the upper end. The structure was heated at 80°C for 2 hours.

[0069] The present invention uses the raised structure on sandpaper as a template to prepare a double-sided microstructured dielectric layer, adds conductive particles (CNTs) to the dielectric layer, and adopts a dielectric layer boss and a polymer electrode bonding structure made of the same material to expand the pressure detection range and significantly improve the sensitivity and response time of the capacitive pressure sensor. The sensor of the present invention has the advantages of simple structure, small size, low cost, and long service life, and is suitable for large-scale application and promotion. Among them, the flat electrode and the microstructured dielectric layer are both made of carbon nanotube-polydimethylsilane (CNTs-PDMS) composite polymer material, which matches the acoustic impedance characteristics of the water body, thereby significantly improving the response capability of underwater sound monitoring. The flexible capacitive pressure sensor of the present invention has broad application prospects, especially in the future military and civilian dual-use fields such as oil exploration, marine communications, underwater navigation and positioning, and target detection. It has important application value.

[0070] Example 3

[0071] This embodiment provides an underwater acoustic monitoring device using the underwater acoustic pressure sensor as a sensitive element. Figure 8As shown, the underwater acoustic monitoring module uses the same equipment as the pressure response module for the test sensor. The sensor is sealed and placed underwater. The sensor is connected to the LCR and the data is received at the terminal device. Using the above equipment, the underwater acoustic detection device can receive underwater sound signals.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An underwater acoustic pressure sensor, characterized in that: The invention comprises an upper flat electrode, a double-sided microstructured dielectric layer and a lower flat electrode arranged in sequence from top to bottom. The upper flat electrode and the lower flat electrode are made of a 7wt% carbon nanotube-polydimethylsilane composite material, and the double-sided microstructured dielectric layer is made of a 2wt% carbon nanotube-polydimethylsilane composite material. The upper and lower surfaces of the double-sided microstructure are distributed with protrusions or depressions.

2. The underwater acoustic pressure sensor according to claim 1, characterized in that: Electrode lead-out terminals are provided at the edge of the upper surface of the upper flat electrode and the edge of the lower surface of the lower flat electrode.

3. The underwater acoustic pressure sensor according to claim 1, characterized in that: The mass ratio of CNTs to PDMS in the upper and lower flat electrodes is 7:100, and the thickness is 50 μm.

4. The underwater acoustic pressure sensor according to claim 1, characterized in that: The double-sided microstructured dielectric layer has a CNTs to PDMS mass ratio of 1:50 and a thickness of 500 μm.

5. A sensor preparation method for preparing the underwater acoustic pressure sensor according to claim 1, characterized in that: The following steps are involved: respectively preparing a flat electrode pre-solution and a double-sided microstructure dielectric layer pre-solution; Manufacturing a double-sided microstructured dielectric layer based on a double-sided microstructured dielectric layer precursor solution; Making a flat electrode based on a flat electrode pre-solution; The fabricated double-sided microstructured dielectric layer and the flat electrode are sequentially subjected to heating treatment and immersion swelling treatment; The processed flat electrode and the double-sided microstructured dielectric layer are cut into a preset shape, stacked and assembled in the order of flat electrode-double-sided microstructured dielectric layer-flat electrode, and pre-pressed to bond the electrode and the dielectric layer into one.

6. A sensor preparation method according to claim 5, characterized in that: The flat electrode pre-solution is a 7 wt % CNTs-PDMS isopropanol solution, which is prepared by dissolving CNTs, PDMS, and a curing agent in isopropanol.

7. A sensor preparation method according to claim 5, characterized in that: The double-sided microstructure dielectric layer pre-solution is a 2 wt % CNTs-PDMS isopropyl alcohol solution, which is prepared by dissolving CNTs, PDMS, and a curing agent in isopropyl alcohol.

8. An underwater acoustic monitoring device, characterized in that: Underwater acoustic monitoring is performed based on the sensor described in claim 1.

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