Gravity self-stabilized trans-medium omnidirectional photoacoustic transducer and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-15
- Publication Date
- 2026-08-11
AI Technical Summary
[0006]本发明的目的是针对现有技术存在的缺点和不足，提供一种重力自稳定的跨介质全向光声换能器及其制备方法，以能解决传统换能器在动态水域中姿态不稳定、激光耦合效率低以及声波辐射方向受限的技术难题
①自适应姿态稳定：利用重力自稳定机制，实现了“黑上明下”的自寻优姿态，彻底解决了动态水域中因换能器倾斜导致的光声耦合失效问题，保证了通信的连续性；
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Abstract
Description
Technical Field
[0001] This invention relates to the field of communication technology, and in particular to a gravity-stabilized transmedium omnidirectional photoacoustic transducer and its fabrication method. Background Technology
[0002] Currently, cross-medium photoacoustic communication has attracted widespread attention as an effective means of connecting airborne platforms and underwater equipment. Its basic principle is to use a high-power pulsed laser to irradiate the water surface or the photoacoustic conversion medium, exciting sound waves through the thermoelastic expansion effect. However, existing photoacoustic transducers mostly adopt planar structures or fixed thin-film structures, which have the following significant drawbacks in practical applications: One drawback is its high attitude sensitivity. Planar photoacoustic transducers have extremely high requirements for the incident angle of the laser, typically requiring perpendicular laser illumination to ensure maximum conversion efficiency. However, in real-world, confined, dynamic water environments, due to wind, waves, or water current disturbances, the transducer may frequently tilt and flip, causing the laser to deviate from the absorption area or increase the incident angle, resulting in a sharp drop in photoacoustic conversion efficiency or even communication interruption.
[0003] The second drawback is its narrow radiation directionality. Traditional platform transducers generate sound waves with strong directionality, primarily propagating vertically. For underwater receiving nodes positioned laterally or obliquely below, the received signal strength is weak, making omnidirectional coverage difficult and severely limiting communication flexibility.
[0004] Thirdly, it has poor environmental robustness. Existing photoacoustic media (such as carbon-based inks) are mostly liquid or semi-solid, which are easily diluted by water or physically damaged, making it difficult to operate stably in confined spaces for a long time.
[0005] In summary, there is an urgent need for a photoacoustic transducer that can adapt to fluctuating environments, has omnidirectional emission capabilities, and exhibits stable performance. Summary of the Invention
[0006] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a gravity-stabilized trans-medium omnidirectional photoacoustic transducer and its fabrication method, thereby solving the technical problems of unstable attitude, low laser coupling efficiency, and limited acoustic radiation direction of traditional transducers in dynamic waters.
[0007] The objective of this invention is achieved as follows: 1. Gravity-stabilized transmedium omnidirectional photoacoustic transducer (hereinafter referred to as photoacoustic transducer) It includes a base layer and a photoacoustic functional layer; the sphere is a solid transparent sphere made of a high molecular polymer with good sound transmission properties; the photoacoustic functional layer is composed of a high molecular polymer doped with strong light-absorbing materials and is coated on the upper hemisphere surface of the sphere.
[0008] This photoacoustic transducer adjusts its internal mass distribution to shift the overall center of gravity towards the lower hemisphere of the sphere, giving it a self-restoring torque under gravity in the liquid. When it is deflected by water flow or waves, the gravitational torque can drive the sphere to quickly restore its balanced posture, ensuring that the black photoacoustic functional layer always faces upward and vertically receives the laser in the air.
[0009] Specifically: The photoacoustic transducer includes a sphere, a substrate layer, a photoacoustic functional layer, a counterweight, and an overall center of gravity. The sphere is a solid sphere. The outer layer of the lower hemisphere is the base layer, and the outer layer of the upper hemisphere is the photoacoustic functional layer. A counterweight is embedded in the bottom of the sphere, and the center of gravity of the whole is located in the lower middle part of the central axis of the sphere.
[0010] 2. Fabrication method of gravity-stabilized transmedium omnidirectional photoacoustic transducer (hereinafter referred to as fabrication method) Includes the following steps: ① Inject transparent polymer raw materials into a spherical mold and pre-embed counterweights, and use vacuum degassing and heating processes to obtain a solid sphere with an eccentric center of gravity; ② Prepare photoacoustic functional slurry, disperse strong light-absorbing nanomaterials in a liquid polymer matrix, and ensure uniform distribution of light-absorbing particles through mechanical and physical means; ③ Apply functional layer coating, using a lift or dip coating process to evenly coat the slurry onto the upper hemisphere surface of the sphere, and ensure that the coverage area is precisely controlled to be half of the sphere area; ④ A photoacoustic functional layer and a substrate layer are bonded together by a secondary curing process to form a stable and flexible chemical bond, ultimately resulting in a photoacoustic transducer with gravity self-stabilizing properties.
[0011] Compared with the prior art, the present invention has the following advantages and positive effects: ① Adaptive attitude stabilization: By utilizing the gravity self-stabilization mechanism, the self-optimizing attitude of "black on top and bright on bottom" is realized, which completely solves the problem of photoacoustic coupling failure caused by transducer tilt in dynamic waters and ensures the continuity of communication. ②Omnidirectional sound wave radiation: The spherical structure combined with the transparent substrate with acoustic impedance matching allows the generated point source sound waves to radiate in an almost spherical omnidirectional manner downwards and laterally into the water body, significantly expanding the communication coverage area. ③ High conversion efficiency and durability: The CB-PDMS composite material layer has extremely high light absorption rate and thermoelastic expansion coefficient, and the cured flexible film layer is resistant to water erosion and does not fall off, ensuring signal strength and long service life.
[0012] In summary, this invention effectively overcomes the problem of photoacoustic conversion failure caused by transducer attitude deflection due to waves in confined dynamic waters, and realizes omnidirectional high-gain acoustic wave emission that is not afraid of interface fluctuations. It has significant advantages such as simple structure, strong environmental robustness, and low manufacturing cost. Attached Figure Description
[0013] Figure 1 This is a structural schematic diagram (cross-section) of a photoacoustic transducer. Figure 2 This is a schematic diagram illustrating the working state of an optical acoustic transducer in an underwater environment and its application scenarios in cross-media communication.
[0014] In the picture: 00-Photoacoustic transducer; 01-Sphere; 02-Matrix layer; 03-Photoacoustic functional layer; 04-Counterweight; 05-Overall center of gravity position; 10 - Water surface; 20-Airborne laser pulse; 30 - Omnidirectional sound wave; 40 - Underwater receiver hydrophone. Detailed Implementation
[0015] The following detailed description, in conjunction with the accompanying drawings and embodiments, is provided. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.
[0016] I. Photoacoustic transducer 00 1. Structure The photoacoustic transducer 00 includes a sphere 01, a substrate layer 02, a photoacoustic functional layer 03, a counterweight 04, and an overall center of gravity position 05; Sphere 01 is a solid sphere. The outer layer of the lower hemisphere is the base layer 02, and the outer layer of the upper hemisphere is the photoacoustic functional layer 03. A counterweight block 04 is embedded in the bottom of sphere 01, and the center of gravity 05 is located in the lower middle part of the central axis of sphere 01.
[0017] 2. Functional components 0) Sphere 01 It is a polymer spherical solid with equal density and sound transmission.
[0018] 1) Matrix layer 02 It is the outer layer of the lower half of a spherical solid.
[0019] 2) Photoacoustic functional layer 03 It is the outer layer of the upper half of the spherical solid, and is composed of a composite material with photothermal conversion properties.
[0020] 3) Counterweight 04 It is a metal ring or a metal bead.
[0021] 4) Overall center of gravity position 05 The center of gravity of sphere 00 is biased towards the center of the lower hemisphere, which makes sphere 01 in a state of gravity-stable vertical equilibrium in the liquid.
[0022] II. Fabrication method of photoacoustic transducer 00 The specific steps are as follows: ① Preparation of transparent PDMS solution and degassing treatment PDMS (polydimethylsiloxane) prepolymer and matching curing agent are mixed at a mass ratio of 10:1. The mixture is stirred clockwise at a constant speed for 10 minutes using a glass rod or mechanical stirrer until it is homogeneous. Then, the mixture is placed in a vacuum drying oven and allowed to stand under a vacuum of -0.1 MPa for 30 minutes until all the tiny bubbles inside and on the surface of the mixture have escaped, resulting in a pure and transparent PDMS stock solution. ② Casting a transparent hemisphere and embedding a counterweight Slowly inject the transparent PDMS stock solution processed in step ① into the lower half of the standard spherical mold. Place a micro high-density metal ring or metal bead in the center at the bottom of the stock solution (i.e. the bottom of the future sphere) as a counterweight 04. Then, place the lower half of the mold containing the stock solution and the counterweight 04 into a constant temperature drying oven at 80°C and heat it for 1 hour to solidify it initially. ③ Casting and Demolding of the Sphere After the lower half of the mold has cured, close the upper half of the spherical mold and continue to inject the remaining transparent PDMS stock solution through the injection hole until the entire spherical mold cavity is filled. Place it in a constant temperature drying oven at 80°C for 2 hours to cure completely. After cooling to room temperature, open the mold and take out the solid transparent sphere with a smooth surface. This gives you sphere 01 with a counterweight 03 embedded inside. At this point, due to the presence of the counterweight 04, the center of gravity of sphere 01 is significantly shifted to the lower half of the sphere. ④ Preparation of CB-PDMS photoacoustic functional slurry Weigh out 10% by mass of nano-sized carbon black powder (CB) and add it to the freshly prepared liquid PDMS mixture. First, use a magnetic stirrer to stir vigorously at room temperature for 2 hours, and then transfer it to an ultrasonic cleaner for 40 minutes of ultrasonic dispersion treatment to completely break up the carbon black agglomerates and obtain a black CB-PDMS slurry with extremely strong light absorption and photothermal conversion capabilities. ⑤ Precisely coat the photoacoustic functional layer Using the dip-coating method, the sphere 01 prepared in step ③ is fixed on the dip-coating machine, and the substrate layer 02 is slowly lowered to precisely immerse it in the CB-PDMS slurry prepared in step ③. The immersion depth is strictly controlled to be half the surface area of the sphere 01 (i.e., accurately covering the entire upper hemisphere surface). After being quickly pulled out, it is left to stand at room temperature for 15 minutes to allow the slurry to level. Finally, it is placed in an 80℃ drying oven for 1 hour to cure. The black film after curing is the photoacoustic functional layer 03. Thus, the omnidirectional photoacoustic transducer 00 is prepared.
[0023] III. Actual Working Mechanism of Optical Acoustic Transducer 00 in Cross-Medium Communication Systems like Figure 2 The system is a cross-media communication system, which includes an optical-acoustic transducer 00, a water surface 10, an airborne laser pulse 20, an omnidirectional acoustic wave 30, and an underwater receiver hydrophone 40.
[0024] The prepared photoacoustic transducer 00 is placed in a confined water area (or test tank). Due to the gravitational pull of the counterweight 04 at the bottom of the sphere 01, the photoacoustic transducer 00 automatically adjusts its posture in the water under the combined action of liquid buoyancy and gravity, achieving a gravity-stabilized suspension or semi-floating state. Under this stable posture, the black photoacoustic functional layer 03 always remains vertically upward, fully exposed to the air or shallow water layer above, while the transparent substrate layer 02 is submerged downward.
[0025] In this state, when the air laser pulse 20 emits a nanosecond-level laser pulse carrying OOK modulation information and shines vertically downward, the laser energy is instantly and completely absorbed by the upward-facing photoacoustic functional layer 03, and the CB-PDMS material undergoes violent local thermoelastic expansion, which excites a broadband photoacoustic shock wave.
[0026] Because the acoustic impedance of the substrate layer 02 (PDMS material) (approximately 1.05 M ayl) is extremely well matched with that of water (approximately 1.5 M ayl), and the spherical geometry naturally possesses acoustic divergence and transmission characteristics, the photoacoustic shock wave can penetrate the substrate layer 02 with extremely low interface emission loss, forming a high-gain omnidirectional acoustic radiation into the water below. At the same time, even if the water surface fluctuates or the water flow impacts, causing the sphere 01 to shake momentarily, the gravity self-restoring torque can restore it to a vertical "black on top, bright on bottom" posture in a very short time, thus completely avoiding signal interruption caused by wave tilting in traditional platform transducers.
[0027] IV. Examples In order to verify the effectiveness of the present invention, the inventors conducted a comparative experiment to optimize the parameters and conduct a comparative experiment.
[0028] Control group: Laser directly irradiates pure water. Due to the low absorption coefficient of 1064nm laser in pure water (about 0.14 / cm), the photothermal effect area is a slender cylindrical shape. The energy density does not reach the photobreakdown threshold, and the hydrophone does not detect an effective sound signal. Experimental group (preferred embodiment of the invention): Photoacoustic functional layer 03 was introduced, and the laser repetition rate was set to 1kHz and the pulse width was set to 200ns. At this time, the laser energy was compressed in the sub-millimeter region of the medium surface, generating a high signal-to-noise ratio N-shaped acoustic wave signal. The experiment shows that the low repetition rate setting effectively avoids the multipath reverberation interference generated by the continuous wave and ensures the accuracy of the zero point of time required by the SAFT algorithm.
[0029] It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the examples described above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A gravity-stabilized transmedium omnidirectional photoacoustic transducer, characterized in that: The photoacoustic transducer (00) includes a sphere (01), a substrate layer (02), a photoacoustic functional layer (03), a counterweight (04), and an overall center of gravity position (05). The sphere (01) is a solid sphere. The outer layer of the lower hemisphere is the base layer (02), and the outer layer of the upper hemisphere is the photoacoustic functional layer (03). A counterweight (04) is embedded in the bottom of the sphere (01), and the center of gravity (05) is located in the lower middle part of the central axis of the sphere (01).
2. The gravity-self-stabilized transmedium omnidirectional photoacoustic transducer according to claim 1, characterized in that: The sphere (01) is a polymer spherical solid with equal density and sound transmission; The substrate layer (02) is the outer layer of the lower half of the spherical solid; The photoacoustic functional layer (03) is the outer layer of the upper half of the spherical solid and is composed of a composite material with photothermal conversion properties; The counterweight (04) is a metal ring or a metal bead; The overall center of gravity position (05) is such that the center of gravity of the sphere (00) is biased towards the center of the lower hemisphere, so that the sphere (01) is in a state of gravity self-stabilization and vertical equilibrium in the liquid.
3. The method for fabricating a gravity-self-stabilized transmedium omnidirectional photoacoustic transducer according to claim 1 or 2, characterized in that: ① To prepare a sphere (01), a solid sphere (01) with an eccentric center of gravity is obtained by injecting transparent polymer raw material into a mold and pre-embedding a counterweight (04) and using vacuum degassing and heating processes. ② Prepare photoacoustic functional slurry, disperse strong light-absorbing nanomaterials in a liquid polymer matrix, and ensure uniform distribution of light-absorbing particles through mechanical and physical means; ③ Coating of the photoacoustic functional layer (03) is carried out by using a lifting or dip coating process to evenly coat the slurry on the lower hemisphere surface of the sphere (01) and ensure that the coverage area is precisely controlled to be half of the sphere area; ④ A photoacoustic functional layer (03) and a substrate layer (02) are formed into a stable flexible chemical bond through a secondary curing process, and finally a photoacoustic transducer (00) with gravity self-stabilizing characteristics is obtained.
4. The preparation method according to claim 3, characterized in that: ① Preparation of transparent PDMS solution and degassing treatment The polydimethylsiloxane prepolymer and the matching curing agent were mixed at a mass ratio of 10:
1. The mixture was stirred clockwise at a constant speed for 10 minutes using a glass rod or mechanical stirrer until it was uniformly mixed. Then, the mixture was placed in a vacuum drying oven and allowed to stand under a vacuum of -0.1 MPa for 30 minutes until all the tiny bubbles inside and on the surface of the mixture were completely released, resulting in a pure and transparent PDMS stock solution. ② Casting a transparent hemisphere and embedding a counterweight Slowly inject the transparent PDMS stock solution after step ① into the lower half of the standard spherical mold. Place a micro high-density metal ring or metal bead in the center of the bottom of the stock solution as a counterweight (04). Then, place the lower half of the mold containing the stock solution and the counterweight (04) into a constant temperature drying oven at 80°C and heat it for 1 hour to allow it to initially set. ③ Casting and demolding of the sphere (01) After the lower half of the mold has solidified, close the upper half of the spherical mold and continue to inject the remaining transparent PDMS liquid through the injection hole until the entire spherical mold cavity is filled. Place it in a constant temperature drying oven at 80°C for 2 hours to completely solidify. After cooling to room temperature, open the mold and take out the solid transparent sphere with a smooth surface. This gives you a sphere (01) with a counterweight (04) embedded inside. At this time, due to the presence of the counterweight (04), the center of gravity of the sphere (01) is obviously biased towards the lower half of the sphere. ④ Preparation of CB-PDMS photoacoustic functional slurry Weigh out 10% of nano-sized carbon black powder and add it to the freshly prepared liquid PDMS mixture. First, use a magnetic stirrer to stir vigorously at room temperature for 2 hours, and then transfer it to an ultrasonic cleaner for 40 minutes of ultrasonic dispersion treatment to completely break up the carbon black agglomerates and obtain a black CB-PDMS slurry with extremely strong light absorption and photothermal conversion capabilities. ⑤ Precisely coat the photoacoustic functional layer Using the dip-coating method, the substrate layer (02) prepared in step ③ is fixed on the dip-coating machine. The substrate layer (02) is slowly lowered and immersed into the CB-PDMS slurry prepared in step ③. The immersion depth is strictly controlled at half the surface area of the substrate layer (02). After being quickly pulled out, it is left to stand at room temperature for 15 minutes to allow the slurry to level. Finally, it is placed in an 80℃ drying oven for 1 hour to cure. The black film after curing is the photoacoustic functional layer (03). Thus, the omnidirectional photoacoustic transducer (00) is prepared.