High-stability liquid metal photoinduced ultrasonic structure and preparation method thereof

Abstract

The invention belongs to the technical field of photoinduced ultrasound, and particularly relates to a high-stability liquid metal photoinduced ultrasound structure and a preparation method thereof. The photoinduced ultrasonic structure comprises a substrate, a photoinduced ultrasonic layer and composite liquid metal particles. The photoinduced ultrasonic layer is arranged on the substrate, and the composite liquid metal particles are dispersed in the photoinduced ultrasonic layer. The composite liquid metal particle is composed of a gallium-based liquid metal core and a sodium alginate coating coated on the surface of the liquid metal core. According to the invention, the sodium alginate coating isolates the contact between the liquid metal core and the external environment, inhibits the oxidation reaction, maintains the photo-thermal performance of the particles, avoids the performance degradation caused by oxidation, and ensures the long-term stability of the photo-induced ultrasonic structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoacoustic technology, and particularly relates to a photoacoustic structure of liquid metal with high stability and a preparation method thereof. Background Art

[0002] With the rapid development of modern optoelectronic technology, photoacoustic technology has attracted extensive attention in the fields of medical imaging, material detection, and industrial non-destructive testing due to its high efficiency in energy conversion. Photoacoustic transducers generate ultrasonic waves by converting light energy into heat energy, and the core lies in the high light absorption ability and efficient photothermal conversion performance of the materials used. Therefore, the performance of photoacoustic materials directly determines the overall efficiency and application effect of the transducers.

[0003] As a new type of functional material, liquid metal exhibits important application potential in the field of photothermal conversion materials due to its unique advantages such as low melting point, high electrical conductivity, and high thermal conductivity. Especially gallium-based liquid metal, with its excellent light absorption ability in a wide spectral range and fast thermal conversion performance, has become a research hotspot in the field of photothermal (Science Advances 8 (2024): 27., Nano Research 12, (2019): 1313.). However, although liquid metal has advantages in photothermal performance, it has a key problem of poor stability in the field of photoacoustics.

[0004] The stability of liquid metal materials is the main bottleneck affecting their performance. Due to the active surface chemical properties of liquid metal, it is extremely easy to oxidize in air or water environments, forming an oxide layer (such as Ga 2 O 3 ). This oxide layer not only significantly reduces the light absorption ability of liquid metal, but also weakens the stability of photothermal conversion performance, resulting in a rapid decline in performance during long-term use of the material. In addition, there is a lack of effective protection mechanisms on the surface of liquid metal particles, and their chemical reactions are further aggravated in high-temperature or high-humidity environments, accelerating the degradation of performance. This problem of poor stability severely restricts the long-term application of liquid metal materials in photoacoustic transducers.

[0005] In summary, although the potential of liquid metal as a photoacoustic material is huge, its limitation of poor stability restricts its wide promotion in practical applications. Summary of the Invention

[0006] To solve the above problems, on the one hand, the present invention provides a liquid metal photoacoustic structure with high stability, including a substrate, a photoacoustic layer, and composite liquid metal particles. The photoacoustic layer is disposed on the substrate, and the composite liquid metal particles are dispersed in the photoacoustic layer. The composite liquid metal particles are composed of a gallium-based liquid metal core and a sodium alginate coating covering the surface of the liquid metal core.

[0007] In the present invention, a sodium alginate coating is covered on the surface of the gallium-based liquid metal core to form composite liquid metal particles with a core-shell structure. The chemical properties of the liquid metal core are active and it is easy to react with oxygen or moisture in the air to form an oxide layer (such as Ga 2 O 3 ), thereby significantly reducing the light absorption ability and photothermal conversion performance. The sodium alginate coating, as a natural polymer material with good chemical stability, can effectively isolate the direct contact between the liquid metal core and the external environment, prevent the penetration of oxygen and moisture, and improve the antioxidant performance of the liquid metal particles. In addition, the sodium alginate coating has good biocompatibility and environmental adaptability, and can still maintain its protective performance under complex working conditions such as high temperature and high humidity, thus ensuring the long-term reliability of the liquid metal particles in the photoacoustic transducer.

[0008] In addition, in terms of light absorption, the polymer network structure of the coating can guide the incident light to form a local light field enhancement region on the surface of the liquid metal particles, enabling the liquid metal core to absorb higher-intensity light energy, thereby enhancing the photothermal response efficiency. Mechanically, the flexible characteristics of the sodium alginate coating play an important role in the ultrasonic vibration process of the photoacoustic layer. Between the liquid metal core and the matrix of the photoacoustic layer, due to the differences in material properties (such as elastic modulus, thermal expansion coefficient, etc.), a rigid direct combination often leads to mechanical stress concentration. Especially during the thermal expansion process caused by the photothermal effect, this stress will inhibit the free vibration of the liquid metal core, thereby weakening the energy conversion efficiency from photothermal conversion to ultrasonic waves. The sodium alginate coating, due to its flexible and low mechanical modulus characteristics, can act as a mechanical adaptation layer and be filled between the liquid metal core and the matrix of the photoacoustic layer. This flexible layer has a certain buffering effect and can effectively absorb and disperse the stress caused by the mismatch of material interfaces, thus avoiding the negative impact of mechanical resistance on the vibration efficiency.

[0009] Furthermore, the substrate is a heat-conducting material. The efficient heat transfer improves the uniformity of photothermal conversion and also enables the long-term operation reliability of the entire structure under high-power light illumination conditions.

[0010] Furthermore, the gallium-based liquid metal includes gallium and indium, and the mass ratio of gallium is 60%-80%.

[0011] Furthermore, the diameter of the composite liquid metal particles is 100 nanometers to 2 micrometers.

[0012] Furthermore, the thickness of the sodium alginate coating is 50 nanometers to 1 micrometer.

[0013] Furthermore, the photoacoustic layer is a polymer matrix, such as PDMS, PMMA, PC, epoxy resin, PVDF, PLA or PU.

[0014] Furthermore, the surface of the substrate is provided with conical pits, and the bottom of the photoacoustic layer fills the pits. The conical pit structure can guide light to undergo multiple reflections and scattering within the pits, extending the propagation path of light in the photoacoustic layer, thereby significantly improving the light absorption efficiency. Additionally, the pit filling design increases the contact area between the photoacoustic layer and the substrate, contributing to improving the heat conduction efficiency, enabling heat to rapidly diffuse in the substrate, avoiding local overheating, and enhancing the reliability during long-term operation. Importantly, when the liquid metal particles in the photoacoustic layer are heated and expand to generate vibrations, the shape of the conical pits can focus and guide the vibration energy to propagate along a specific direction, effectively avoiding the dispersion of vibration energy, improving the directivity of the ultrasonic wave, making it have stronger signal concentration, enhancing the output intensity of the ultrasonic wave, ensuring more efficient vibration energy transfer, and thus optimizing the performance of the ultrasonic wave in high-precision applications.

[0015] Furthermore, a silver film is provided on the surface of the conical pits, and the photoacoustic layer covers the silver film. The high reflectivity of the silver film can generate multiple light reflections within the conical pits, extending the propagation path of light in the photoacoustic layer, thereby enhancing the light trapping effect. This multiple reflection mechanism ensures that more incident light energy can be efficiently absorbed by the liquid metal particles, greatly improving the photothermal conversion efficiency. Additionally, as a high thermal conductivity material, the silver film can quickly transfer the heat generated in the photothermal effect to the substrate, avoiding the problem of local heat accumulation. This efficient heat diffusion ability not only improves the thermal management performance of the photoacoustic structure but also ensures the stability and intensity of the ultrasonic wave output, enhancing the reliability of the overall performance.

[0016] On the other hand, the present invention provides a method for preparing a liquid metal photoacoustic structure with high stability, including the following steps: Step 1, prepare an aqueous solution of sodium alginate; Step 2, add a gallium-based liquid metal to the aqueous solution of sodium alginate, and stir and ultrasonically treat to form composite liquid metal particles; Step 3, disperse the composite liquid metal particles into a polymer matrix, and then set it on a substrate.

[0017] Furthermore, in Step 3, centrifugal deposition is first carried out, followed by drying or heat curing treatment. Centrifugal deposition is a technique that uses centrifugal force to uniformly deposit particles onto the surface of a substrate. During centrifugal deposition, a dispersion containing composite liquid metal particles is placed in a rotating device, and the centrifugal force generated by high-speed rotation pushes the particles in the dispersion radially towards the surface of the substrate for deposition. Among them, the magnitude of the centrifugal force is proportional to the mass of the particles, and the mass of the particles is proportional to the cube of their diameter. Therefore, under the same centrifugal conditions, the centrifugal force acting on large particles is significantly higher than that on small particles. This causes large particles to be more easily and quickly pushed to the surface of the substrate under the action of centrifugal force and deposited preferentially, forming a distribution where large particles are close to the substrate and small particles are far from the substrate. This gradient distribution structure extends the propagation path of light in the photoacoustic layer, ensuring that more light energy is absorbed layer by layer by the particles, thereby improving the photothermal conversion efficiency and overall light absorption performance.

[0018] Advantages of the present invention: (1) The sodium alginate coating isolates the liquid metal core from the external environment, inhibits the oxidation reaction, maintains the photothermal properties of the particles, avoids performance degradation caused by oxidation, and ensures the long-term stability of the photoacoustic structure.

[0019] (2) Through the design of composite liquid metal particles, the gallium-based liquid metal core has high photothermal conversion performance, while the sodium alginate coating can reduce light scattering losses and extend the action time of light on the particle surface, thereby significantly improving the light absorption efficiency.

[0020] (3) The flexible property of the sodium alginate coating forms a mechanical adaptation layer between the liquid metal core and the photoacoustic layer matrix, which can buffer the interfacial stress caused by thermal expansion, reduce mechanical resistance, ensure the efficient conversion of the photothermal effect into ultrasonic vibration, and improve the ultrasonic output efficiency and signal stability.

[0021] Combining the above beneficial effects, the present invention has good application prospects in the field of photoacoustic technology. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of a highly stable liquid metal photoacoustic structure.

[0023] Figure 2 It is an optical microscope image of liquid metal nanoparticles wrapped with a sodium alginate coating.

[0024] Figure 3 It is a schematic diagram of another highly stable liquid metal photoacoustic structure.

[0025] In the figure: 1. Substrate; 2. Photoacoustic layer; 3. Composite liquid metal particles. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of this application more clear and understandable, the following provides further detailed descriptions of this application with reference to the accompanying drawings and by way of examples.

[0027] Example 1 The present invention provides a liquid metal photoacoustic structure with high stability, as Figure 1 shown, its structure includes a substrate 1, a photoacoustic layer 2, and composite liquid metal particles 3 dispersed in the photoacoustic layer 2.

[0028] (1) Substrate 1: The substrate 1 is a heat-conducting material, preferably copper or aluminum, with excellent heat-conducting performance, capable of quickly conducting the heat generated by the photothermal effect and avoiding local heat accumulation. In addition, the surface of the substrate 1 is finely processed with a low surface roughness and has strong adhesion to the photoacoustic layer 2. The thickness of the substrate 1 is 1 mm to 5 mm.

[0029] (2) Photoacoustic layer 2: The photoacoustic layer 2 is composed of a polymer matrix. Preferably polydimethylsiloxane (PDMS), which has the advantages of good flexibility and good light transmittance, and is helpful for the transmission of light energy and the output of ultrasonic waves. The photoacoustic layer 2 is disposed on the substrate 1, and the thickness of the photoacoustic layer 2 is 10 μm to 500 μm.

[0030] (3) Composite liquid metal particles 3: The composite liquid metal particles 3 are composed of a gallium-based liquid metal core and a sodium alginate coating wrapped on the surface of the core. Figure 2 This is an optical microscope image of the composite liquid metal particles prepared in our laboratory. The composite liquid metal particles have an obvious core-shell structure, and the sodium alginate coating tightly wraps the liquid metal core. The gallium-based liquid metal is composed of an alloy of gallium and indium, where the mass ratio of gallium is 60% - 80%. The diameter range of the composite liquid metal particles 3 is 100 nm to 2 μm, and the thickness of the sodium alginate coating is 50 nm to 1 μm. These particles are uniformly dispersed in the photoacoustic layer and achieve a gradient distribution through centrifugal deposition technology, that is, a distribution structure where large particles are close to the substrate and small particles are far from the substrate. This design effectively optimizes the light absorption path and heat conduction performance.

[0031] Preferably, as Figure 3As shown, the surface of the substrate 1 is designed with an array of conical pits to enhance the light trapping ability. The depth of each conical pit is about 10 microns, the top diameter is about 20 microns, and the spacing between the pits is about 0 to 50 microns. By guiding the incident light through multiple reflections and scatterings, the conical pit array improves the light absorption efficiency. More preferably, a silver film with a high reflectivity is deposited on the surface of the conical pits to enhance the light trapping ability. The silver film is prepared by physical vapor deposition technology, and the film thickness is about 80 nanometers. The silver film enhances the local light field intensity and improves the light absorption efficiency of the photoacoustic layer 2. The bottom of the photoacoustic layer 2 is tightly filled in the conical pits and covers the surface of the silver film at the same time. The bonding force between the photoacoustic layer 2 and the substrate 1 is enhanced through interface treatment. The surface of the substrate 1 is micro-roughened after depositing the silver film to form a nanoscale roughness, which improves the adhesion of the photoacoustic layer 2. The photoacoustic layer filled in the conical pits is tightly bonded to the silver film, further enhancing the structural stability and avoiding the interface slip caused by photothermal expansion through mechanical cooperation. Such a liquid metal photoacoustic structure can be applied to fields such as biomedical imaging, non-destructive testing, and industrial sensing. Its photothermal conversion performance and ultrasonic output ability ensure the reliability and accuracy in a variety of complex application scenarios.

[0032] Preferably, in the design of the photoacoustic layer 2 of the present invention, the density of the composite liquid metal particles 3 is distributed in a layered manner. The density of the bottom layer particles close to the substrate 1 is relatively large, while the density of the top layer particles far from the substrate 1 is relatively small. This density gradient design can fully optimize the photothermal conversion and ultrasonic output performance: the high-density particles in the bottom layer enhance the primary light absorption and heat conduction efficiency, quickly transfer the heat to the substrate, avoid local heat accumulation, and at the same time generate stronger thermal expansion vibrations to increase the ultrasonic output intensity; the low-density particles in the top layer extend the light propagation path, further absorb the multiply reflected light, improve the light energy utilization rate, and reduce the vibration resistance to improve the directivity and consistency of the ultrasonic waves. This layered structure realizes the synergistic optimization of the photoacoustic layer in terms of light absorption, thermal management, and vibration output performance.

[0033] Preferably, in the design of the photoacoustic layer 2 of the present invention, the surface PDMS matrix far from the substrate 1 is treated by reactive ion etching (etching gas is oxygen, power is 100W, time is 10min). The patterning mask is a parallel grid array, the structural period is 3 - 10 microns, and periodic microstructures are formed on its surface after etching. This characteristic of gradually changing the surface refractive index from air (refractive index = 1) to PDMS (refractive index = 1.4) can maximize the antireflection effect. The PDMS microstructures obtained by this method not only reduce the surface reflection loss, but also cooperate with the silver film on the substrate to increase the light reflection path. The two work together to increase the light absorption rate to >95%, ensuring that the incident light efficiently enters the photothermal layer.

[0034] Preferably, graphene sheets are embedded in the sodium alginate coating to form a composite coating, enhancing the mechanical strength and durability of the coating while maintaining flexibility and transparency, and improving the overall performance of the photoacoustic layer 2.

[0035] Example 2 The present invention provides a method for preparing a liquid metal photoacoustic structure with high stability, comprising the following steps: Step 1: Prepare an aqueous sodium alginate solution. Specifically, take sodium alginate powder with a mass concentration of 0.5% and add it to deionized water, stir evenly until completely dissolved to form a uniform and transparent aqueous sodium alginate solution. Subsequently, perform ultrasonic degassing treatment on the solution (power: 100 W, time: 15 minutes) to eliminate the bubbles in the solution and improve the stability of the solution.

[0036] Step 2: Add gallium-based liquid metal to the aqueous sodium alginate solution, and stir and perform ultrasonic treatment to form composite liquid metal particles. Specifically, select gallium and indium as the raw materials for the liquid metal core, where the mass ratio of gallium is 70% and the mass ratio of indium is 30%. After mixing gallium and indium in proportion, slowly heat to 50 °C and stir until a uniform liquid metal alloy is formed. Dropwise add the liquid metal alloy to the prepared aqueous sodium alginate solution while stirring to ensure the uniform dispersion of the liquid metal in the solution. Subsequently, perform ultrasonic treatment (power: 200 W, time: 30 minutes). Utilize the mechanical and dispersion effects of ultrasonic waves to uniformly coat the surface of the liquid metal particles with sodium alginate, forming composite liquid metal particles 3 with a core-shell structure. After the coating is completed, centrifuge the solution (centrifugation speed: 3000 rpm, time: 10 minutes), collect the composite liquid metal particles 3, and wash them 3 times with deionized water to remove the excess sodium alginate. The washed particles are dried at 50 °C to obtain composite liquid metal particles 3 with a diameter range of 100 nanometers to 2 micrometers and a coating thickness of 50 nanometers to 1 micrometer.

[0037] Step 3: Disperse the composite liquid metal particles 3 into the polymer matrix and then set it on the substrate 1. Specifically, PDMS is selected as the polymer matrix. Mix it according to the mass ratio of PDMS matrix to crosslinking agent of 10:1, stir evenly and then let it stand for 30 minutes to remove air bubbles. Add the prepared composite liquid metal particles into the PDMS matrix at a volume fraction of 20%, and through stirring and ultrasonic treatment (power is 150 W, time is 20 minutes), make the particles evenly dispersed in the polymer matrix to avoid particle aggregation. Pour the mixture evenly onto the prepared copper substrate, and then place it in a centrifuge for centrifugal deposition treatment (centrifugal speed is 4000 rpm, time is 5 minutes). Through the centrifugal force, the composite liquid metal particles form a gradient distribution, where the large particles are deposited in the area close to the substrate and the small particles are distributed in the area far from the substrate. After the deposition is completed, place the substrate together with the photoacoustic layer in an oven and conduct thermal curing treatment at 80 °C for 2 hours to ensure that the photoacoustic layer is completely cured and tightly adheres to the substrate surface.

[0038] Preferably, conical pits are prepared on the surface of the copper substrate by micro-nano processing technology. The depth of the pits is 10 microns, the top diameter is 20 microns, and the surface spacing of the pits is 50 microns, forming an array distribution structure. Coat a silver film on the surface of the conical pits, and the thickness of the silver film is 80 nanometers, which is realized by physical vapor deposition process. The silver film can enhance the reflection of light and the local light field intensity, and improve the light absorption efficiency of the photoacoustic layer. Fill the prepared photoacoustic layer 2 material into the pits and make it in close contact with the silver film to further enhance the interfacial bonding force and heat transfer performance.

[0039] For the density stratification design of the composite liquid metal particles 3, first, prepare PDMS, mix and stir evenly according to the mass ratio of matrix to crosslinking agent of 10:1, and then add the composite liquid metal particles 3, and the volume fraction of the particles in the polymer matrix is 30%. Ensure the uniform distribution of the particles through stirring and ultrasonic treatment (power 150W, time 20 minutes). Pour the mixture onto the surface of the substrate 1 and conduct centrifugal deposition (4000 rpm, 5 minutes) to form a particle distribution layer with a thickness of 100 microns. Through thermal curing treatment at 80 °C for 2 hours, make the photoacoustic layer completely cured and combined with the substrate. Then, use the same polymer matrix formula, adjust the volume fraction of the composite liquid metal particles 3 to 10%, and make the particles evenly distributed through stirring and ultrasonic treatment. Coat the mixture on the underlying photoacoustic layer 2 to form a particle distribution layer with a thickness of 50 microns. To ensure the uniformity of the stratified structure, use the static sedimentation method to make the particles naturally distribute, and then conduct thermal curing (80 °C, 2 hours).

[0040] To further enhance the shape stability of the liquid metal core, the present invention introduces a porous microstructure as a support framework in the photoacoustic layer, and composite liquid metal particles are placed in its pores. The porous microstructure is made of porous silicon material with high strength and low density, the pore diameter ranges from 500 nanometers to 5 micrometers, the porosity is 50% - 80%, and the thickness is 50 micrometers to 200 micrometers. The composite liquid metal particles are filled into the porous microstructure by solution infiltration method, and the capillary action is used to evenly distribute the particles and tightly embed them in the pores, ensuring that the liquid metal is restricted by the porous framework under high temperature or vibration environment, significantly reducing shape changes, while maintaining the photothermal conversion efficiency. In addition, the high thermal conductivity of the porous microstructure can optimize the heat conduction path, effectively disperse local heat, and further improve the stability and output performance of the photoacoustic structure. This design not only enhances the mechanical stability of the liquid metal core, but also has the characteristics of lightweight and efficient thermal management.

[0041] Furthermore, a treatment step of pre-stretching - plasma treatment - stress release is performed on the porous microstructure to further enhance the strain adaptability and ultrasonic frequency stability of the photoacoustic layer by regulating the surface morphology and mechanical response characteristics of the porous microstructure.

[0042] Preferably, the porous silicon thin film is fixed to a biaxial stretching device, and a pre-stretching force is synchronously applied along the X-axis to 60% of the maximum elastic deformation of the material and maintained in the stretched state for 5 - 10 minutes. Then, in the pre-stretched state, the porous silicon thin film is placed in a plasma cleaner, nitrogen is introduced, the cleaning power is set to 100 W, and the treatment time is 5 - 10 minutes. Finally, the stretching force is gradually released at a rate of 1 mm / s, causing the porous silicon thin film to retract and form a periodic wrinkled structure. Through this step, the wrinkled structure and the porous structure cooperate to disperse stress, suppress the ultrasonic frequency shift caused by the deformation of liquid metal particles, and expand the application scenarios of photoacoustics to wearable devices and curved imaging fields.

[0043] The liquid metal photoacoustic structure of the present invention is mainly applied to fields such as biomedical imaging, non-destructive testing, and industrial sensing, and its usage method is as follows: The prepared photoacoustic structure is installed in a photoacoustic transducer and connected to a laser light source and an ultrasonic detection device. During use, the light emitted by the laser light source is focused on the surface of the photoacoustic layer 2 through an optical path system, and the composite liquid metal particles 3 absorb light energy and convert it into heat energy, and the thermal expansion effect causes ultrasonic vibrations. The conical pit and silver film design can enhance the light capture and reflection, optimize the photothermal conversion efficiency, and at the same time, the high thermal conductivity of the substrate 1 evenly disperses heat to ensure the stable operation of the device. The output ultrasonic waves are collected by a sensing device and used for imaging or detection of the target area. Thanks to the high photothermal conversion performance and stability of the present invention, the system can provide reliable ultrasonic signals in complex scenarios with high-precision requirements.

[0044] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the scope of protection of the present application.

Claims

1. A liquid metal photo-induced ultrasonic structure with high stability, characterized in that: The invention comprises a substrate, a photo-induced ultrasound layer and composite liquid metal particles; the photo-induced ultrasound layer is arranged on the substrate, and the composite liquid metal particles are dispersed in the photo-induced ultrasound layer; the composite liquid metal particles are composed of a gallium-based liquid metal core and a sodium alginate coating coated on the surface of the liquid metal core.

2. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 1, characterized in that: The substrate is a thermally conductive material.

3. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 1, characterized in that: The gallium-based liquid metal includes gallium and indium, wherein the mass ratio of gallium is 60%-80%.

4. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 1, characterized in that: The diameter of the composite liquid metal particles is 100 nanometers to 2 micrometers.

5. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 4, characterized in that: The thickness of the sodium alginate coating is 50 nanometers to 1 micrometer.

6. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 1, characterized in that: The photoinduced ultrasound layer is a polymer matrix.

7. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 1, characterized in that: The surface of the substrate is provided with conical pits, and the bottom of the photo-induced ultrasound layer is filled with the pits.

8. The liquid metal photo-induced ultrasonic structure with high stability as claimed in claim 7, characterized in that: A silver film is provided on the surface of the conical pit, and the photo-induced ultrasound layer covers the silver film.

9. A method for preparing a liquid metal photo-induced ultrasonic structure with high stability, characterized in that: The steps include: Step 1, preparing sodium alginate aqueous solution; Step 2, adding gallium-based liquid metal to the sodium alginate aqueous solution, stirring and ultrasonically treating to form composite liquid metal particles; Step 3: Disperse the composite liquid metal particles into a polymer matrix and then place them on a substrate.

10. The method for preparing a liquid metal photo-induced ultrasonic structure with high stability according to claim 9, characterized in that: In step 3, centrifugal deposition is first used, followed by drying or heat curing.

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