A fast photocured low acoustic impedance ultrasonic matching layer material and a preparation method thereof

Abstract

The application belongs to the technical field of ultrasonic transducers, and particularly relates to a low acoustic impedance ultrasonic matching layer material capable of being rapidly photocured and a preparation method thereof, which comprises photosensitive resin, hollow glass microbeads, a photoinitiator and an additive; the preparation method comprises the following steps: 1. mixing the photosensitive resin and the photoinitiator in proportion, fully stirring, and forming a uniform resin premix; 2. adding the hollow glass microbeads and the additive to the resin premix, stirring to uniformly disperse, and forming a composite slurry; 3. performing vacuum debubbling treatment on the composite slurry to obtain debubbled composite slurry; and 4. pouring the debubbled composite slurry into a forming mold, performing a photocuring reaction under ultraviolet light irradiation, and forming a low acoustic impedance ultrasonic matching layer. The low acoustic impedance ultrasonic matching layer has a simple preparation process, a stable material system, is suitable for batch preparation of ultrasonic matching layers, and has a uniform structure, good stability, and improved transmission efficiency of ultrasonic signals at the interface.

Description

Technical Field

[0001] This application belongs to the field of ultrasonic transducer technology, specifically relating to a rapidly photocurable low acoustic impedance ultrasonic matching layer material and its preparation method. Background Technology

[0002] Ultrasonic transducers are widely used in gas flow detection, gas safety monitoring, and industrial process control. To improve the transmission efficiency of ultrasonic signals at interfaces between different media, an acoustic matching layer is typically placed between the piezoelectric material and the measured medium. The matching layer achieves effective transmission of acoustic energy at the interface by adjusting the acoustic impedance, thereby reducing reflection loss and increasing signal transmittance.

[0003] Existing matching layers are typically prepared using epoxy resin and inorganic filler composite materials, but they suffer from the following technical problems:

[0004] (1) The curing time is relatively long.

[0005] (2) The preparation process is complex and it is difficult to achieve rapid prototyping.

[0006] (3) It is difficult to accurately control the thickness of the matching layer.

[0007] Therefore, there is an urgent need for a new matching layer material that can achieve rapid curing, adjustable acoustic impedance, and simple preparation process. Summary of the Invention

[0008] To address the aforementioned technical problems in the existing technology, the purpose of this invention is to develop an ultrasonic matching layer material that can be rapidly cured, has adjustable acoustic impedance, and is simple to prepare. The technical solution is as follows:

[0009] A rapidly photocurable low acoustic impedance ultrasonic matching layer material comprises: a photosensitive resin, hollow glass microspheres, a photoinitiator, and additives; the photosensitive resin serves as a matrix material for undergoing a UV curing reaction under the action of the photoinitiator; the hollow glass microspheres serve as a low-density filler for forming a low acoustic impedance basic composite system; and the additives are used to improve the dispersibility and processing performance of the material.

[0010] Furthermore, the photosensitive resin is ethoxylated trimethylolpropane triacrylate (ETPTA).

[0011] Furthermore, the hollow glass microspheres have a mass fraction of 15% to 20% and a particle size range of 20 μm to 120 μm.

[0012] Furthermore, the photoinitiator has a mass fraction of 1% to 2%; and the UV curing reaction time is 2s to 5s.

[0013] Furthermore, the additives include one or more of defoamers, dispersants, or leveling agents; the mass fraction of the additives is 1% to 4%.

[0014] A method for preparing a low acoustic impedance ultrasonic matching layer based on a rapidly photocurable low acoustic impedance ultrasonic matching layer material includes the following steps:

[0015] Step 1: Mix the photosensitive resin and the photoinitiator in a certain proportion and stir thoroughly to form a uniform resin premix.

[0016] Step 2: Add hollow glass microspheres and additives to the resin premix, stir to disperse them evenly, and form a composite slurry;

[0017] Step 3: Perform vacuum degassing on the composite slurry to remove air bubbles and obtain the degassed composite slurry;

[0018] Step 4: Pour the degassed composite slurry into an ultrasonic gasket matching layer molding template with a preset molding cavity thickness, and perform a photocuring reaction under ultraviolet light irradiation to form a low acoustic impedance ultrasonic matching layer with controllable thickness.

[0019] Furthermore, in step 4, the materials used to prepare the low acoustic impedance ultrasonic matching layer include: 80-85 parts by weight of photosensitive resin, 15-20 parts by weight of hollow glass microspheres, 1-2 parts by weight of photoinitiator, and 1-4 parts by weight of defoamer.

[0020] Furthermore, in step 4, the thickness of the low acoustic impedance ultrasonic matching layer is 0.8–1.2 mm; the thickness of the preset molding cavity is 0.8–1.2 mm.

[0021] Furthermore, in step 4, the method for preparing the ultrasonic pad matching layer molding template with a preset molding cavity thickness includes the following steps:

[0022] (1) Take a PDMS solution and crosslinking agent in a 10:1 ratio according to the mass fraction and put them in a container. Stir with a glass rod to make them evenly mixed to prepare the template mixture.

[0023] (2) Apply UV adhesive evenly to the lower surface of the smooth circular mold and stick it on the petri dish, then cure it by UV irradiation;

[0024] (3) Pour the template mixture into the culture dish and place it in a homogenizer to remove bubbles until there are no bubbles or only tiny, dense bubbles.

[0025] (4) Transfer the defoamed culture dish to a constant temperature box for curing and demolding to obtain the ultrasonic pad matching layer molding template.

[0026] Furthermore, the thickness of the ultrasonic gasket matching layer molding template is 16-20 mm; the constant temperature curing conditions for the ultrasonic gasket matching layer molding template are: curing at a constant temperature of 80 degrees for 1 hour, or curing at a constant temperature of 65 degrees for 2 hours.

[0027] Beneficial effects: (1) The present invention uses a photosensitive resin system, which can be rapidly cured by ultraviolet light irradiation, greatly shortening the preparation time of the matching layer. (2) The present invention controls the thickness of the matching layer by using a PDMS molding template with a preset molding cavity thickness, thereby adjusting the equivalent input acoustic impedance, reflection coefficient and sound energy transmission characteristics of the matching layer under specific working frequency and load medium, and realizing the controllable design of acoustic matching effect. (3) The preparation process of the present invention is simple, the material system is stable, and it is suitable for the batch preparation of ultrasonic matching layers. (4) The matching layer prepared by the present invention has a uniform structure and good stability, which can effectively improve the transmission efficiency of ultrasonic signals at the interface. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for preparing the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention.

[0029] Figure 2 This is a flowchart illustrating the fabrication process of the rapidly photocurable low acoustic impedance ultrasonic matching layer molding template of the present invention.

[0030] Figure 3 The images show actual photographs of the rapid photocuring low acoustic impedance ultrasonic matching layer molding template of the present invention and macroscopic schematic diagrams of embodiments of the low acoustic impedance ultrasonic matching layer.

[0031] Figure 4A This is a macroscopic view of the physical object of Embodiment 1 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention;

[0032] Figure 4B This is a macroscopic view of the physical object of Embodiment 2 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention;

[0033] Figure 4C This is a macroscopic view of the physical embodiment 3 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention;

[0034] Figure 4a This is an enlarged view of the internal structure of Embodiment 1 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention;

[0035] Figure 4b This is an enlarged view of the internal structure of Embodiment 2 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention;

[0036] Figure 4c This is an enlarged view of the internal structure of Example 3 of the rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0038] The rapid photocurable low acoustic impedance ultrasonic matching layer material of the present invention comprises: photosensitive resin, hollow glass microspheres, photoinitiator, and additives; wherein, the photosensitive resin serves as a matrix material for undergoing ultraviolet light curing reaction under the action of the photoinitiator; the hollow glass microspheres serve as a low-density filler for forming a low acoustic impedance basic composite system; and the additives are used to improve the dispersibility and processing performance of the material.

[0039] Preferably, the photosensitive resin of the present invention is ethoxylated trimethylolpropane triacrylate (ETPTA). The mass fraction of the hollow glass microspheres is 15% to 20%. This range can reduce the matching layer density while ensuring good flowability and dispersion stability of the composite slurry, avoiding insufficient low-density effect due to too low a mass fraction of hollow glass microspheres, or excessive a mass fraction leading to increased slurry viscosity, microsphere agglomeration, and molding defects. The particle size range of the hollow glass microspheres is 20 μm to 120 μm. This particle size range is beneficial for uniform dispersion in the photosensitive resin and reducing large air bubbles and agglomeration defects; too small a particle size will increase the specific surface area of ​​the system and increase the viscosity of the slurry, while too large a particle size will easily cause local non-uniformity and reduced surface smoothness. The mass fraction of the photoinitiator is 1% to 2%. This range can quickly initiate cross-linking and curing of the photosensitive resin under ultraviolet light irradiation, while avoiding incomplete curing due to insufficient initiator or affecting material stability due to excessive initiator. The ultraviolet curing reaction time is 2s to 5s. The additives include one or more of defoamers, dispersants, or leveling agents; the mass fraction of the additives is 1% to 4%, which is beneficial for reducing air bubbles during mixing and molding, improving the uniformity of hollow glass microsphere dispersion, and the surface smoothness of the matching layer.

[0040] like Figure 1 As shown, the present invention also provides a method for preparing a low acoustic impedance ultrasonic matching layer based on the aforementioned rapidly photocurable low acoustic impedance ultrasonic matching layer material, specifically including the following steps:

[0041] S1: Mix the photosensitive resin and photoinitiator in a certain proportion and stir thoroughly to form a uniform resin premix.

[0042] S2: Add hollow glass microspheres and additives to the resin premix and stir to disperse them evenly to form a composite slurry;

[0043] S3: Vacuum degassing treatment is performed on the composite slurry to remove air bubbles and obtain the degassed composite slurry.

[0044] S4: Pour the degassed composite slurry into an ultrasonic gasket matching layer molding template with a preset molding cavity thickness, and perform a photocuring reaction under ultraviolet light irradiation to form a low acoustic impedance ultrasonic matching layer with controllable thickness.

[0045] The rapidly photocurable low acoustic impedance ultrasonic matching layer of the present invention can be disposed on the forward acoustic radiation surface of a piezoelectric ceramic sheet, a piezoelectric composite material sheet, or other piezoelectric transducer to form an acoustic transition layer facing a gaseous medium; the gaseous medium includes one or more of air, natural gas, fuel gas, hydrogen-blended gas, carbon dioxide, nitrogen, or industrial process gases.

[0046] like Figure 2 As shown, the method for preparing the ultrasonic pad matching layer molding template with a preset molding cavity thickness includes the following steps:

[0047] (1) Take a PDMS solution and crosslinking agent in a 10:1 ratio according to the mass fraction and put them in a container. Stir with a glass rod to make them evenly mixed to prepare the template mixture.

[0048] (2) Apply UV adhesive evenly to the lower surface of the smooth circular mold and stick it on the petri dish, then cure it by UV irradiation;

[0049] (3) Pour the template mixture into the culture dish and place it in a homogenizer to remove bubbles until there are no bubbles or only tiny, dense bubbles.

[0050] (4) Transfer the defoamed culture dish to a constant temperature incubator for curing and demolding to obtain the ultrasonic pad matching layer molding template, as shown below. Figure 3 As shown.

[0051] Preferably, the thickness of the low acoustic impedance ultrasonic matching layer of the present invention is 0.8–1.2 mm; this thickness range corresponds to the acoustic matching requirements at the commonly used operating frequencies of gas ultrasonic sensors, and the equivalent input acoustic impedance and transmission effect of the matching layer can be adjusted by changing the phase delay of the sound wave in the matching layer. The preset molding cavity thickness is 0.8–1.2 mm, used to replicate and control the thickness of the ultrasonic matching layer. The thickness of the ultrasonic gasket matching layer molding template is 16–20 mm, used to ensure the structural strength and demolding stability of the template. The isothermal curing conditions for the ultrasonic gasket matching layer molding template are: curing at 80 degrees Celsius for 1 hour, or curing at 65 degrees Celsius for 2 hours.

[0052] The materials used to prepare the low acoustic impedance ultrasonic matching layer include: 80-85 parts by weight of photosensitive resin, 15-20 parts by weight of hollow glass microspheres, 1-2 parts by weight of photoinitiator, and 1-4 parts by weight of defoamer.

[0053] In this invention, the intrinsic acoustic impedance of the low acoustic impedance ultrasonic matching layer material is mainly determined by the density and sound velocity of the composite material. However, under actual operating conditions of the ultrasonic transducer, the matching layer with a finite thickness will also exhibit an equivalent input acoustic impedance related to its thickness. Therefore, this invention achieves controllable adjustment of the acoustic matching effect of the matching layer by pre-setting the molding cavity thickness of the molding template, using the thickness parameter as a single variable, to meet the needs of different ultrasonic sensor structures and application scenarios.

[0054] The low acoustic impedance ultrasonic matching layer of the present invention, made from a rapidly photocurable low acoustic impedance ultrasonic matching layer material, can be disposed on the forward acoustic radiation surface of a piezoelectric ceramic sheet, a piezoelectric composite material sheet, or other piezoelectric transducer to form an acoustic transition layer facing a gaseous medium; the gaseous medium includes one or more of air, natural gas, fuel gas, hydrogen-blended gas, carbon dioxide, nitrogen, or industrial process gases.

[0055] This invention can be used for the forward acoustic radiation surface of transducers for gas ultrasonic detection, especially suitable for ultrasonic transmitting / receiving probes in air, natural gas, fuel gas, hydrogen-blended gases, and other industrial gas environments. For transducers with different center frequencies, different piezoelectric sheet sizes, or different gas media, PDMS molding templates with corresponding molding cavity thicknesses can be prepared by changing the circular molds of different thicknesses, thereby quickly obtaining an ultrasonic matching layer with the correct thickness, meeting the requirements of the following application scenarios: (a) Multi-frequency transducer adaptation—when the operating frequency of the gas ultrasonic sensor changes from 40kHz, 200kHz to 1MHz, the optimal thickness of the matching layer (usually λ / 4) changes accordingly. By changing the circular mold, a matching layer of the corresponding thickness can be obtained within minutes without remixing the material system; (b) Multi-gas medium matching—different gas media have significant differences in characteristic acoustic impedance (e.g., air approximately 430 Rayl, natural gas approximately 380 Rayl, hydrogen-blended gases approximately 200 Rayl). (c) Rapid prototyping – In the early stages of laboratory research and product development, researchers can use molding templates of different thicknesses to quickly produce samples, screen the optimal matching layer thickness parameters, and significantly shorten the iteration cycle; (d) Sensor array customization – In multi-channel gas detection arrays, each channel may require different frequency response characteristics. By changing the corresponding molding template, matching layers of multiple specifications can be prepared at once.

[0056] Example 1

[0057] like Figure 1As shown, the rapid photocuring low acoustic impedance ultrasonic matching layer processing procedure of the present invention involves the following steps: 80 parts by weight of photosensitive resin are weighed into container A, and 2 parts of photoinitiator are added. Under conditions of non-direct sunlight or in the dark, the mixture is thoroughly stirred using a glass plate to form a homogeneous system, thus preparing a resin premix. Another container B is placed on a balance, and the balance is zeroed. 20 parts of hollow glass microspheres are weighed using a spatula. The resin premix is ​​then slowly and evenly dripped into container B using a pipette or dropper. A glass plate is slowly rotated counterclockwise along the inner wall of container B, gradually reducing the radius of rotation until the resin premix and hollow glass microspheres form a homogeneous mixture, thus preparing a composite slurry. One part of defoamer is added to the composite slurry, mixed thoroughly, and then degassed under vacuum to obtain the slurry to be cured.

[0058] like Figure 2 As shown, the rapid photocuring low acoustic impedance ultrasonic matching layer molding template processing process of the present invention involves weighing 10 parts of PDMS solution into a beaker by weight, adding 1 part of crosslinking agent to the beaker using a pipette, and stirring counterclockwise for 8-15 minutes with a clean glass rod to ensure uniform mixing, thus obtaining the template mixture. A smooth, 0.8mm thick circular mold is evenly coated with UV glue and adhered to a petri dish. The petri dish is then inverted on a worktable and placed directly under a UV lamp. The power is turned on, and UV light is irradiated onto the area where the petri dish adheres to the circular mold until the mold is completely bonded to the petri dish (ideally 8 minutes). The template mixture is slowly poured into the petri dish until the liquid level reaches d=16mm. The petri dish is then placed horizontally into a homogenizer, and the power is turned on to seal and defoam. During defoaming, the line of sight is kept level with the liquid surface until no bubbles are visible or only small, dense bubbles remain, at which point the homogenizer is turned off. After defoaming, the culture dish is transferred to a constant temperature chamber. The temperature of the constant temperature chamber is set to 65 degrees Celsius and left to stand for 2 hours. After curing, the disc mold is removed and the disc mold is removed. This produces an ultrasonic pad matching layer molding template with a cavity of a specific thickness.

[0059] The prepared ultrasonic pad matching layer molding template is placed under a UV lamp. The pre-prepared slurry to be cured is evenly added into the molding template. A glass slide is used to flatten the liquid surface. The UV lamp is then turned on, and the slurry is irradiated for 2 seconds to obtain a low acoustic impedance ultrasonic matching layer. Figure 4a As shown, the surface and internal structure of the ultrasonic matching layer were observed using an electron microscope. It was found that the glass microspheres inside the matching layer were uniformly distributed, without obvious impurities, large air bubbles, or defects such as microsphere agglomeration.

[0060] After macroscopic measurement, such as Figure 4A As shown, the ultrasound matching layer is a white, circular sheet with a relatively hard texture, a diameter of 11.63 mm, a thickness of 0.82 mm, and a density of 0.632 g / cm³. 3The compression modulus was measured to be 142.67 N / mm² using a universal mechanical compressor. 2 For the measurement of the flatness of the ultrasonic gasket, a horizontal reference plane was specified, and the average height error between the four edge points of the gasket and the center point was measured. The measured error was 0.087 mm.

[0061] Example 2

[0062] like Figure 1 As shown, the rapid photocuring low acoustic impedance ultrasonic matching layer processing procedure of the present invention comprises, by weight, 85 parts of photosensitive resin, 15 parts of hollow glass microspheres with a particle size of 20-120 μm, 1 part of photoinitiator, and 4 parts of additives. The remaining steps are repeated in Example 1.

[0063] like Figure 2 As shown, the rapid photocuring low acoustic impedance ultrasonic matching layer molding template processing process of the present invention involves weighing 10 parts of PDMS solution and adding 1 part of crosslinking agent by mass to make the mixture uniform. A smooth, 1mm thick circular mold is then attached to a petri dish using UV glue and fixed by UV irradiation. The mixture is then slowly poured into the petri dish until the liquid level reaches d=18mm. The mixture is then connected to a homogenizer to remove bubbles and placed in an 80°C constant temperature oven for 1 hour. After curing, the mold is demolded to obtain an ultrasonic gasket matching layer molding template of a specific thickness.

[0064] The prepared ultrasonic pad matching layer molding template is placed under a UV irradiation lamp. The pre-prepared slurry to be cured is evenly added into the molding template. A glass slide is used to flatten the liquid surface. The UV irradiation lamp is then turned on and irradiated for 3 seconds to prepare the low acoustic impedance ultrasonic matching layer. Figure 4b As shown, the surface and internal structure of the ultrasonic matching layer were observed using an electron microscope. It was found that the glass microspheres inside the matching layer were uniformly distributed, without obvious impurities, large air bubbles, or defects such as microsphere agglomeration.

[0065] After macroscopic measurement, such as Figure 4B As shown, the ultrasound matching layer is a white, circular sheet with a relatively hard texture, a diameter of 11.67 mm, a thickness of 1.02 mm, and a density of 0.664 g / cm³. 3 Compression modulus 165.84 N / mm 2 The error between the average of the four edge points of the gasket and the absolute height of the center point was measured and found to be 0.945 mm.

[0066] Example 3

[0067] like Figure 1The rapid photocuring process for the low acoustic impedance ultrasonic matching layer shown involves weighing out 82 parts by weight of photosensitive resin, 18 parts by weight of hollow glass microspheres with a particle size of 20–120 μm, 2 parts by weight of photoinitiator, and 3 parts by weight of additives. The remaining steps are repeated in Example 1.

[0068] like Figure 2 The process of rapidly photocuring low acoustic impedance ultrasonic matching layer molding template shown is as follows: 10 parts of PDMS solution are weighed and 1 part of crosslinking agent are added to make the mixture uniform. The surface is smoothed and a 1.2 mm thick circular mold is attached to a petri dish using UV glue and fixed by UV irradiation. The mixture is then slowly poured into the petri dish until the liquid level reaches d=20 mm. The mixture is then connected to a homogenizer to remove bubbles and placed in a 65-degree constant temperature oven for 2 hours. After curing, the mold is demolded to obtain an ultrasonic gasket matching layer molding template of a specific thickness.

[0069] The prepared ultrasonic pad matching layer molding template is placed under a UV lamp. The pre-prepared slurry to be cured is evenly added into the molding template. A glass slide is used to flatten the liquid surface. The UV lamp is then turned on, and the slurry is irradiated for 4 seconds to obtain a low acoustic impedance ultrasonic matching layer. Figure 4c As shown, the surface and internal structure of the ultrasonic matching layer were observed using an electron microscope. It was found that the glass microspheres inside the matching layer were uniformly distributed, without obvious impurities, large air bubbles, or defects such as microsphere agglomeration.

[0070] After macroscopic measurement, such as Figure 4C As shown, the ultrasound matching layer is a white, circular sheet with a relatively hard texture, a diameter of 11.61 mm, a thickness of 1.23 mm, and a density of 0.664 g / cm³. 3 Compression modulus 154.35 N / mm 2 The error between the average height of the four edge points of the gasket and the absolute height of the center point was measured and found to be 0.985 mm.

[0071] The performance characteristics of the rapidly photocurable low acoustic impedance ultrasonic matching layers prepared in each embodiment are shown in Table 1 below:

[0072] Table 1 Performance characteristics of the ultrasound matching layer in each embodiment

[0073]

[0074] Table 1 shows that the molding templates prepared using circular molds of different thicknesses can stably obtain ultrasonic matching layers with thicknesses of approximately 0.82 mm, 1.02 mm, and 1.23 mm, respectively, indicating that the present invention can achieve control over the matching layer thickness through the molding template; the densities of the various embodiments are between 0.632 and 0.664 g / cm³. 3The range of compressive modulus is 142.67–165.84 N / mm². 2 The range indicates that the resulting matching layer possesses both low density and certain mechanical stability. Considering the influence of thickness on the equivalent input acoustic impedance, the method of this invention enables rapid photocuring, controllable thickness, and adjustable acoustic matching effects. Therefore, the rapidly photocured low acoustic impedance ultrasonic matching layer prepared by the method of this invention demonstrates that the method possesses excellent preparation repeatability and process stability. As shown in the above examples, within the same hollow glass microsphere mass fraction range (15%~20%), matching layers of different thicknesses can be stably obtained simply by changing the molding mold thickness (0.8mm, 1.0mm, 1.2mm), thereby achieving different equivalent input acoustic impedance and sound energy transmission characteristics at a given operating frequency. This acoustic impedance control strategy of "fixed material formulation, only adjusting mold thickness" avoids the problems of slurry viscosity, dispersibility, and mechanical property fluctuations caused by adjusting acoustic impedance by changing filler content, resulting in better process controllability and acoustic consistency, and is particularly suitable for industrial applications requiring rapid customization of multi-specification matching layers.

[0075] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A rapidly photocurable low acoustic impedance ultrasonic matching layer material, comprising: Photosensitive resin, hollow glass microspheres, photoinitiator, and additives; characterized in that the photosensitive resin serves as a matrix material for undergoing ultraviolet light curing under the action of the photoinitiator; the hollow glass microspheres serve as a low-density filler for forming a low acoustic impedance basic composite system; and the additives are used to improve the dispersibility and processing performance of the material.

2. The rapidly photocurable low acoustic impedance ultrasonic matching layer material according to claim 1, characterized in that, The photosensitive resin is ethoxylated trimethylolpropane triacrylate (ETPTA).

3. The rapidly photocurable low acoustic impedance ultrasonic matching layer material according to claim 1, characterized in that, The hollow glass microspheres have a mass fraction of 15% to 20% and a particle size range of 20 μm to 120 μm.

4. The rapidly photocurable low acoustic impedance ultrasonic matching layer material according to claim 1, characterized in that, The photoinitiator has a mass fraction of 1% to 2%; the UV curing reaction time is 2s to 5s.

5. The rapidly photocurable low acoustic impedance ultrasonic matching layer material according to claim 1, characterized in that, The additives include one or more of defoamers, dispersants, or leveling agents; the mass fraction of the additives is 1% to 4%.

6. A method for preparing a low acoustic impedance ultrasonic matching layer based on the rapidly photocurable low acoustic impedance ultrasonic matching layer material according to claim 1, characterized in that, Includes the following steps: Step 1: Mix the photosensitive resin and photoinitiator in a certain proportion and stir thoroughly to form a uniform resin premix. Step 2: Add hollow glass microspheres and additives to the resin premix, stir to disperse them evenly, and form a composite slurry; Step 3: Perform vacuum degassing on the composite slurry to remove air bubbles and obtain the degassed composite slurry; Step 4: Pour the degassed composite slurry into an ultrasonic gasket matching layer molding template with a preset molding cavity thickness, and perform a photocuring reaction under ultraviolet light irradiation to form a low acoustic impedance ultrasonic matching layer with controllable thickness.

7. The method for preparing a rapidly photocurable low acoustic impedance ultrasonic matching layer according to claim 6, characterized in that, In step 4, the materials used to prepare the low acoustic impedance ultrasonic matching layer include: 80-85 parts by weight of photosensitive resin, 15-20 parts by weight of hollow glass microspheres, 1-2 parts by weight of photoinitiator, and 1-4 parts by weight of defoamer.

8. The method for preparing a rapidly photocurable low acoustic impedance ultrasonic matching layer according to claim 6, characterized in that, In step 4, the thickness of the low acoustic impedance ultrasonic matching layer is 0.8–1.2 mm; the thickness of the preset molding cavity is 0.8–1.2 mm.

9. The method for preparing a rapidly photocurable low acoustic impedance ultrasonic matching layer according to claim 6, characterized in that, In step 4, the method for preparing the ultrasonic pad matching layer molding template with a preset molding cavity thickness includes the following steps: (1) Take a PDMS solution and crosslinking agent in a 10:1 ratio according to the mass fraction and put them in a container. Stir with a glass rod to make them evenly mixed to prepare the template mixture. (2) Apply UV adhesive evenly to the lower surface of the smooth circular mold and stick it on the petri dish, then cure it by UV irradiation; (3) Pour the template mixture into the culture dish and place it in a homogenizer to remove bubbles until there are no bubbles or only tiny, dense bubbles. (4) Transfer the defoamed culture dish to a constant temperature box for curing and demolding to obtain the ultrasonic pad matching layer molding template.

10. A method for preparing a rapidly photocurable low acoustic impedance ultrasonic matching layer according to claim 6 or 9, characterized in that, The thickness of the ultrasonic gasket matching layer molding template is 16-20 mm; the constant temperature curing conditions of the ultrasonic gasket matching layer molding template are: curing at 80 degrees Celsius for 1 hour, or curing at 65 degrees Celsius for 2 hours.

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