Liquid metal film and preparation method and application thereof

Abstract

The invention belongs to the technical field of laser precision machining, and provides a liquid metal film and a preparation method and application thereof. The preparation method comprises the following steps: spraying dispersion liquid of liquid metal nanoparticles on a transparent substrate to obtain a processing material; the side, sprayed with the liquid metal nanoparticles, of the processing material is opposite to one side of the target substrate; and laser is focused on the interface of the transparent substrate and the liquid metal nanoparticles for laser processing. The invention further discloses the liquid metal film prepared according to the method and a flexible conductive device comprising the liquid metal film. According to the method, the liquid metal is patterned by utilizing the recoil pressure generated by gasification in the sintering process, so that the selection of the target substrate is more diversified, the selection of the processing pattern is more flexible, and the step of separating the conductive liquid metal film from the untreated liquid metal nanoparticles is omitted; on the premise that high precision of liquid metal patterning is guaranteed, high efficiency and high flexibility are achieved at the same time.

Description

Technical Field

[0001] The present disclosure relates to the field of laser precision processing technology, and in particular to a liquid metal film and a preparation method and application thereof. Background Art

[0002] Liquid metal materials such as gallium-based alloys have excellent flexibility and conductivity and are ideal materials for preparing flexible conductive devices. The patterning of liquid metal is the key to the preparation of liquid metal flexible conductive devices. However, the extremely large surface energy of liquid metal itself makes it difficult to wet flexible substrates. This makes the existing patterning technology face certain challenges in achieving high-precision preparation of high-quality conductive films. Ultrasonic treatment of liquid metal to obtain liquid metal nanoparticles can overcome the surface energy of liquid metal, but the oxide layer on the surface of each liquid metal nanoparticle isolates the nanoparticles from each other and cannot form a conductive path. Therefore, how to sinter liquid metal nanoparticles so that the nanoparticles form a conductive path between each other has become the focus of the current liquid metal patterning process. There are various problems with the current sintering technology: under the premise of ensuring processing accuracy, evaporation sintering, photon sintering and thermal sintering often require liquid metal nanoparticles to be deposited on the substrate by mask printing and other methods to obtain various patterns, which makes its processing flexibility poor. In addition, except for photon sintering, the processing efficiency of other sintering methods is low, for example, evaporation sintering requires a day of drying process.

[0003] In summary, there is still a lack of liquid metal patterning technology that can ensure processing accuracy and conductive properties while having the advantages of high processing efficiency, good processing flexibility and low requirements on the substrate. Summary of the invention

[0004] The present disclosure provides a liquid metal film and a preparation method and application thereof, so as to at least solve the above technical problems existing in the prior art.

[0005] According to a first aspect of the present disclosure, a method for preparing a liquid metal film is provided, comprising the following steps:

[0006] Spraying a dispersion of liquid metal nanoparticles on a transparent substrate to obtain a processed material;

[0007] The side of the processing material sprayed with liquid metal nanoparticles is placed opposite to the side of the target substrate; laser is focused on the interface between the transparent substrate and the liquid metal nanoparticles for laser processing to obtain the liquid metal film.

[0008] According to an implementable embodiment of the present disclosure, at least the following beneficial effects are achieved:

[0009] The present invention uses pulsed laser to selectively sinter liquid metal nanoparticles, and the processing pattern can be changed at will through software, so that the processing pattern has great flexibility in selection. At the same time, the recoil pressure generated by gasification during the sintering process is used to separate the conductive liquid metal film from the untreated liquid metal nanoparticles, eliminating the complicated separation steps.

[0010] Specifically, the present invention sprays liquid metal nanoparticles on the surface of a transparent substrate, and then places the side of the transparent substrate sprayed with the liquid metal nanoparticles opposite to the side of the target substrate. Laser is incident from the side of the transparent substrate on which the liquid metal nanoparticles are not sprayed, and the impact generated by the vaporization of the liquid metal nanoparticles under pulse laser irradiation is utilized to propel the liquid metal nanoparticles to the surface of the target substrate while forming a film under laser processing, while the liquid metal nanoparticles that are not processed by the laser remain on the original transparent substrate, and a conductive liquid metal film with a certain pattern is obtained on the surface of the target substrate.

[0011] In one embodiment, the dispersion of liquid metal nanoparticles is prepared by the following method: subjecting liquid metal to ultrasonic treatment to obtain the dispersion of liquid metal nanoparticles.

[0012] Specifically, the liquid metal, dispersant and solvent are mixed and ultrasonically treated to obtain a dispersion of the liquid metal nanoparticles.

[0013] Specifically, the liquid metal is selected from at least one of gallium-indium alloy, gallium-indium-tin alloy, and bismuth-indium-tin-zinc alloy.

[0014] Specifically, the dispersant is selected from at least one of 3-mercapto-N-nonylpropionamide, polyacrylamide, sodium dodecyl sulfate, and fatty acid polyethylene glycol esters.

[0015] Specifically, the selection of the above dispersant is not particularly limited, as long as the liquid metal can be dispersed in the solvent.

[0016] Specifically, the solvent is selected from at least one of anhydrous ethanol, isopropanol, glycerol, and dimethyl sulfoxide.

[0017] Specifically, the mass ratio of the liquid metal to the dispersant is 160:1 to 90:1.

[0018] Specifically, the ultrasonic treatment time is 2h to 5h.

[0019] In one embodiment, the diameter of the liquid metal nanoparticles is 20 nm to 600 nm.

[0020] In one embodiment, the transparent substrate is selected from any one of sapphire, quartz glass, aluminum nitride, and polyethylene terephthalate (PET).

[0021] In one possible implementation manner, the transparent substrate has a thickness of 0.5 mm to 1.5 mm.

[0022] In one possible implementation manner, after the dispersion of the liquid metal nanoparticles is sprayed on the transparent substrate, a liquid metal nanoparticle film is formed; the thickness of the liquid metal nanoparticle film is 1 μm to 20 μm.

[0023] In one embodiment, the target substrate is placed on a translation stage, the processing material is placed on a side of the target substrate away from the translation stage, and a side of the processing material sprayed with the liquid metal nanoparticles is opposite to a side of the target substrate away from the translation stage.

[0024] In one embodiment, the target substrate is selected from any one of quartz glass, silicon wafer, sapphire, PI film, and PDMS.

[0025] Specifically, the target substrate can be flexibly selected and can be any common substrate. To ensure the transfer effect, the surface of the target substrate should be sufficiently clean and flat and have a certain heat resistance.

[0026] Specifically, the present invention utilizes the recoil force generated by the vaporization of liquid metal nanoparticles to achieve liquid metal patterning, making the choice of target substrate more diverse, and silicone elastomers including PDMS, sapphire sheets, glass, silicon wafers, PI films, etc. can be selected.

[0027] In one embodiment, the laser is incident from a side of the processing material on which the liquid metal nanoparticles are not sprayed.

[0028] In one embodiment, the laser is emitted from a laser, expanded and collimated by a lens, passes through a power adjustment module, enters a scanning galvanometer and a 4F system, is focused by an objective lens, and is imported into a processing file to set appropriate laser power, repetition frequency, and scanning speed for the laser processing.

[0029] In one possible implementation mode, the laser processing method is line-by-line scanning; the laser scanning path planning is: designing a processing graphic, filling the scanning lines into the graphic, scanning the outline of the graphic after completing the internal scanning of the graphic, and converting the final scanning path into a processing file that can be recognized by the processing equipment.

[0030] Specifically, scanning the outline of the pattern after scanning the interior of the pattern can make the patterned liquid metal more firmly fixed on the target substrate.

[0031] Specifically, the liquid metal nanoparticles disclosed in the present invention are formed into films and patterned at the same time. To prepare a conductive liquid metal film of a specific pattern, it is only necessary to spray the liquid metal nanoparticles directly and evenly on the surface of a transparent substrate, and then set the scanning path of the laser, without the need for additional pre-steps (depositing the liquid metal nanoparticles on the substrate surface in a specific pattern by various printing methods) or subsequent steps (after the laser processing is completed, the conductive liquid metal film formed after the laser processing is separated from the non-conductive liquid metal nanoparticles that have not been laser processed by various methods). In addition, the method disclosed in the present invention also has the potential to prepare liquid metal films with three-dimensional structures (such as pyramids).

[0032] In one possible implementation, the laser is a nanosecond laser.

[0033] In one possible implementation manner, the wavelength of the laser is 532 nm to 1650 nm, the repetition frequency is 2 kHz to 20 kHz, the pulse width is less than 100 ns, and the single pulse energy required for processing is greater than 0.3 mJ.

[0034] In one possible implementation, the scanning speed of the laser is 50 mm / s to 3000 mm / s, the scanning range is -25° to 25°, the spot diameter is 30 μm to 44 μm, and the scanning line distance is 30 μm to 44 μm.

[0035] According to a second aspect of the present disclosure, a liquid metal film prepared according to the above preparation method is provided.

[0036] According to a third aspect of the present disclosure, a flexible conductive device is provided, wherein the flexible conductive device comprises the above-mentioned liquid metal film.

[0037] Specifically, the present invention utilizes the advantages of laser direct writing technology (such as wide application of materials, fast speed, high precision and good flexibility), so that liquid metal patterning has high efficiency and high flexibility while ensuring high precision. It has broad application prospects in the manufacture of flexible conductive devices such as flexible circuits, and is expected to achieve large-scale industrial applications.

[0038] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0040] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0041] Figure 1 A technical schematic diagram of laser-induced liquid metal patterning in Embodiment 1 and Embodiment 2 of the present disclosure is shown; specifically, a schematic cross-sectional diagram of a processed sample perpendicular to its thickness direction;

[0042] Figure 2 The effect diagram of the liquid metal film transferred to the target substrate in Example 1 of the present disclosure is shown;

[0043] Figure 3 The scanning electron microscope photographs of the liquid metal film transferred to the surface of the target substrate in Example 1 of the present disclosure are shown; wherein a) is a scanning electron microscope photograph at 400 times, and b) is a scanning electron microscope photograph at 2000 times;

[0044] Figure 4 The effect diagram of the liquid metal film transferred to the target substrate in Example 2 of the present disclosure is shown.

[0045] Reference numerals:

[0046] 1-nanosecond laser; 2-objective lens; 3-transparent substrate; 4-liquid metal nanoparticles; 5-target substrate. DETAILED DESCRIPTION

[0047] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0048] Flexible conductive devices are basic components in flexible electronic applications. Liquid metal materials such as gallium-based alloys have excellent flexibility and conductivity and are ideal materials for preparing flexible conductive devices. The patterning of liquid metal is the key to the preparation of liquid metal flexible conductive devices. However, the extremely large surface energy of liquid metal itself makes it difficult to wet flexible substrates. This makes existing patterning technologies, such as contact printing, template transfer, and nozzle direct writing, face certain challenges in achieving high-precision preparation of high-quality conductive films. On the other hand, liquid metal is easily oxidized and wrapped by a non-conductive solid oxide layer. This oxide layer allows liquid metal to wet heterogeneous surfaces, indicating that the surface energy of liquid metal can be overcome by ultrasonically treating liquid metal to obtain liquid metal nanoparticles. However, each liquid metal nanoparticle has an oxide layer of about 1 to 3 nm on its surface, isolating the nanoparticles from each other. Because the oxide layer is non-conductive, a conductive path cannot be formed between liquid metal nanoparticles. Therefore, how to sinter liquid metal nanoparticles so that the nanoparticles form a conductive path between each other has become the focus of the current liquid metal patterning process. At present, the sintering technologies of liquid metal nanoparticles mainly include photon sintering, evaporation sintering, thermal sintering, mechanical sintering, etc. These sintering technologies have various problems: under the premise of ensuring processing accuracy, evaporation sintering, photon sintering and thermal sintering often require liquid metal nanoparticles to be deposited on the substrate by mask printing and other methods to obtain various patterns, which makes their processing flexibility poor. In addition, except for photon sintering, the processing efficiency of other sintering methods is low. For example, evaporation sintering requires a day of drying process.

[0049] Laser direct writing technology uses high-energy focused light spots to flexibly scan in three dimensions in space to achieve material processing. It has the characteristics of wide application of materials, high precision and good flexibility. Laser direct writing technology can provide photothermal energy to cause nanoparticles to break due to the mismatch in thermal expansion between liquid metal and its oxide layer, resulting in the nanoparticles connecting to each other to form a conductive path. With its advantages, laser direct writing technology has the potential to break through the current process bottlenecks in terms of graphics accuracy, process stability, processing efficiency and scalability. However, laser processing of liquid metal is a multi-physical field process involving light, heat and force, and its mechanism of action and process parameters are relatively complex. Therefore, the interaction mechanism between liquid metal and laser and its impact on the graphics process are still under study.

[0050] In summary, there is still a lack of liquid metal patterning technology that can ensure processing accuracy and conductive properties while having the advantages of high processing efficiency, good processing flexibility and low requirements on the substrate.

[0051] In view of the deficiencies of the above-mentioned prior art, the technical problem to be solved by the present disclosure is: on the basis of pulse laser direct writing technology, a liquid metal graphics method is proposed, which has the advantages of high processing efficiency, good processing flexibility and low requirements on the substrate while ensuring processing accuracy and conductive performance. The liquid metal is ultrasonically treated to obtain liquid metal nanoparticles, and then the liquid metal nanoparticles are sprayed on a transparent substrate. The nanosecond laser is focused on the interface between the liquid metal nanoparticles and the transparent substrate for scanning, so that the liquid metal nanoparticles at the interface are rapidly heated and vaporized, and the recoil pressure generated by the vaporization causes the broken liquid metal nanoparticles in the laser scanning area to be connected to each other to form a conductive film and pushed onto the target substrate, completing the sintering and graphics process of the liquid metal nanoparticles. The laser direct writing technology uses a galvanometer to control the deflection of the laser beam to achieve high-speed processing under the premise of high precision, and the processing graphics can be changed at will through software, and the processing is flexible enough. Since this technology uses the recoil pressure generated by vaporization during laser sintering to push the processed conductive liquid metal film to the surface of the target substrate, it has lower requirements for the target substrate and also eliminates the complicated process of separating the conductive liquid metal film from the unsintered liquid metal nanoparticles.

[0052] The following is a specific description through examples.

[0053] Example 1

[0054] This embodiment prepares a liquid metal film, and the specific process is as follows:

[0055] The transparent substrate is a double-polished sapphire sheet with a thickness of 0.5 mm and a size of 2 inches. The target substrate is a solidified PDMS. The liquid metal conductive film is transferred by the vaporization propulsion of liquid metal nanoparticles under pulsed laser irradiation, and a rectangular liquid metal film with a length of 9 mm and a width of 2 mm with good conductive properties is obtained on the surface of the target substrate.

[0056] (1) Sample preparation before processing:

[0057] First, 360 mg of eutectic gallium-indium alloy (75% Ga and 25% In by mass fraction) and 2.8 mg of 3-mercapto-N-nonyl propionamide were added to 4 mL of anhydrous ethanol, and then ultrasonicated for 3 h to obtain a dispersion of liquid metal nanoparticles, which was then diluted to 40 mL with anhydrous ethanol after ultrasonic treatment. The dispersion of liquid metal nanoparticles was sprayed onto the surface of a double-polished sapphire sheet using a spray gun, and a 60 mg liquid metal nanoparticle film was obtained on the sapphire surface after the anhydrous ethanol evaporated.

[0058] The PDMS agent A and agent B were mixed and stirred in a mass ratio of 10:1, and then degassed in a vacuum for 2 hours to remove bubbles. The uncured PDMS was then introduced into the mold and placed at 60°C in a vacuum for 2 hours to finally obtain the cured PDMS as the target substrate.

[0059] (2) Liquid metal patterning using nanosecond lasers:

[0060] Place PDMS on the translation stage, and place a double-polished sapphire sheet with liquid metal nanoparticles sprayed on the surface on the PDMS, with the side sprayed with liquid metal nanoparticles in contact with the side of the PDMS facing away from the translation stage. The nanosecond laser is incident from the side of the double-polished sapphire sheet that is not sprayed with liquid metal nanoparticles. The translation stage is controlled to adjust the focal length so that the nanosecond laser is focused on the interface between the double-polished sapphire sheet and the liquid metal nanoparticles. Draw the processing graphics in the control software: a rectangle with a length of 9 mm and a width of 2 mm, and then fill the scanning line into the graphics, turn on the laser and start scanning. After the scan is completed, remove the double-polished sapphire sheet, and you can get the following on the PDMS surface. Figure 2 The transfer effect is shown. Figure 2 After the processing is completed, a rectangular liquid metal film with a length of 9 mm and a width of 2 mm is fixed on the surface of the target substrate, demonstrating the high fidelity of the patterning process and verifying the feasibility and high accuracy of the present disclosure. Figure 3 As shown, Figure 3 It shows that the liquid metal nanoparticles transferred from the surface of the transparent double-polished sapphire sheet to the surface of the PDMS have formed a film. The sintered liquid metal nanoparticles are connected to each other, making the film have good conductive properties, confirming that the liquid metal nanoparticles form a conductive path after laser sintering.

[0061] In this embodiment, the optical parameters of the laser are set as follows: wavelength of 1064 nm, pulse width of 5 ns, repetition frequency of 10 kHz, scanning speed of 1500 mm / s, and single pulse energy required for processing of 0.5 mJ.

[0062] The laser scanning path is set as follows: the laser scanning line pitch is 30 μm, the scanning path is evenly filled inside the processed pattern, and after the pattern scanning is completed, another scan is performed along the pattern contour to make the liquid metal film transferred on the target substrate more firmly fixed on the target substrate.

[0063] The schematic diagram of the above laser-induced liquid metal patterning is shown in Figure 1Specifically, the nanosecond laser 1 passes through the objective lens 2 and the transparent substrate 3 and is focused at the interface between the transparent substrate 3 and the liquid metal nanoparticles 4. The liquid metal nanoparticles 4 near the interface are rapidly heated and vaporized under the action of the nanosecond laser 1 to generate a recoil force. The nearby liquid metal nanoparticles 4 are heated and formed into a film under the action of the nanosecond laser 1. At the same time, the recoil force impacts the liquid metal film with good conductive properties onto the surface of the target substrate 5, thereby realizing the patterning of the liquid metal.

[0064] Example 2

[0065] This embodiment prepares a liquid metal film, and the specific process is as follows:

[0066] The transparent substrate is a double-polished sapphire sheet with a thickness of 0.5 mm and a size of 2 inches. The target substrate is a silicon wafer with a thickness of 0.38 mm and a size of 2 inches. Figure 1 The figure shows a schematic cross-sectional view of the processed sample perpendicular to its thickness direction. The liquid metal conductive film is transferred by the vaporization propulsion of liquid metal nanoparticles under pulsed laser irradiation, and a 3×3 liquid metal film array consisting of squares with a side length of 3 mm is obtained on the target substrate surface.

[0067] (1) Sample preparation before processing:

[0068] First, 360 mg of eutectic gallium-indium alloy (75% Ga and 25% In by mass fraction) and 2.8 mg of 3-mercapto-N-nonyl propionamide were added to 4 mL of anhydrous ethanol, and then ultrasonicated for 3 h to obtain a dispersion of liquid metal nanoparticles, which was then diluted to 40 mL with anhydrous ethanol after ultrasonic treatment. The dispersion of liquid metal nanoparticles was sprayed onto the surface of a double-polished sapphire sheet using a spray gun, and a 60 mg liquid metal nanoparticle film was obtained on the sapphire surface after the anhydrous ethanol evaporated.

[0069] Meanwhile, the silicon wafer was placed in deionized water and ultrasonically cleaned for 10 min as the target substrate.

[0070] (2) Liquid metal patterning using nanosecond lasers:

[0071] Place the silicon wafer on the translation stage, and place the double-polished sapphire wafer with liquid metal nanoparticles sprayed on the surface on the silicon wafer, with the side sprayed with liquid metal nanoparticles in contact with the side of the silicon wafer facing away from the translation stage. The nanosecond laser is incident from the side of the double-polished sapphire wafer that is not sprayed with liquid metal nanoparticles, and the translation stage is controlled to adjust the focal length so that the nanosecond laser is focused on the interface between the double-polished sapphire wafer and the liquid metal nanoparticles. Draw the processing graphics in the control software: a 3×3 array composed of squares with a side length of 3mm, and then fill the scanning lines into the graphics, turn on the laser to start scanning. After the scan is completed, remove the double-polished sapphire wafer, and the following can be obtained on the surface of the silicon wafer. Figure 4 The transfer effect is shown. Figure 4 The results show that after processing, a 3×3 liquid metal film array consisting of squares with a side length of 3 mm is fixed on the surface of the target substrate, demonstrating the high fidelity of the imaging process. Unlike PDMS, which is an elastomer, silicon wafers are hard and brittle materials. Figure 4 The transfer effect verifies the high versatility of the present disclosure for target substrates with different characteristics.

[0072] In this embodiment, the optical parameters of the laser are set as follows: wavelength of 1064 nm, pulse width of 5 ns, repetition frequency of 2 kHz, scanning speed of 300 mm / s, and single pulse energy required for processing of 0.41 mJ.

[0073] The laser scanning path is set as follows: the laser scanning line pitch is 30 μm, the scanning path is evenly filled inside the processed pattern, and after the pattern scanning is completed, another scan is performed along the pattern contour to make the liquid metal film transferred on the target substrate more firmly fixed on the target substrate.

[0074] Example 3

[0075] This embodiment prepares a liquid metal film, and the specific preparation process is the same as that of Embodiment 1. However, in this embodiment, the wavelength of the laser is 532 nm, the repetition frequency is 20 kHz, the pulse width is 95 ns, the scanning speed is 50 mm / s, and the scanning line pitch is 44 μm.

[0076] Example 4

[0077] This embodiment prepares a liquid metal film, and the specific preparation process is the same as that of Embodiment 1. However, in this embodiment, the wavelength of the laser is 1650 nm, the pulse width is 50 ns, the scanning speed is 3000 mm / s, and the scanning line pitch is 44 μm.

[0078] The above embodiments all use pulsed laser to selectively sinter liquid metal nanoparticles, and the processing pattern can be changed at will through software, so that the processing pattern has great flexibility in selection. At the same time, the recoil pressure generated by gasification during the sintering process is used to complete the separation between the conductive liquid metal film and the untreated liquid metal nanoparticles, eliminating the complicated separation steps.

[0079] Comparative Example 1

[0080] This comparative example prepares a liquid metal film, which is different from Example 1 in that this comparative example adopts a photon sintering method to prepare the liquid metal film. That is, firstly, liquid metal nanoparticles are deposited on a substrate by mask printing to obtain a target pattern, and then an intense pulse light flash lamp is used to heat the printed liquid metal nanoparticles to destroy the oxide layer, thereby generating a conductive path to prepare the liquid metal film.

[0081] This comparative example requires that liquid metal nanoparticles be first deposited on a substrate by mask printing to obtain a target pattern, and its processing flexibility is relatively poor.

[0082] Comparative Example 2

[0083] This comparative example prepares a liquid metal film, which is different from Example 1 in that the liquid metal nanoparticles are not sprayed on the transparent substrate first, but the liquid metal nanoparticles are directly sprayed on the target substrate for laser direct writing. The rest of the process is the same as Example 1.

[0084] In this comparative example, since no transparent substrate is provided, liquid metal nanoparticles are directly sprayed on the target substrate for laser processing. During the sintering process, the formed liquid metal film and the untreated liquid metal nanoparticles are mixed together, and the two need to be separated later, resulting in a complicated process.

[0085] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of this disclosure can be achieved, and this document is not limited here.

[0086] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0087] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing a liquid metal film, characterized in that: The following steps are involved: Spraying a dispersion of liquid metal nanoparticles on a transparent substrate to obtain a processed material; The side of the processing material sprayed with liquid metal nanoparticles is placed opposite to the side of the target substrate; laser is focused on the interface between the transparent substrate and the liquid metal nanoparticles for laser processing to obtain the liquid metal film.

2. The preparation method according to claim 1, characterized in that: The dispersion of the liquid metal nanoparticles is prepared by the following method: subjecting liquid metal to ultrasonic treatment to obtain the dispersion of the liquid metal nanoparticles; Preferably, the liquid metal, dispersant and solvent are mixed and ultrasonically treated to obtain a dispersion of the liquid metal nanoparticles; Preferably, the liquid metal is selected from at least one of gallium-indium alloy, gallium-indium-tin alloy, and bismuth-indium-tin-zinc alloy; Preferably, the mass ratio of the liquid metal to the dispersant is 160:1 to 90:

1.

3. The preparation method according to claim 1, characterized in that: The transparent substrate is selected from any one of sapphire, quartz glass, aluminum nitride, and polyethylene terephthalate; Preferably, the transparent substrate has a thickness of 0.5 mm to 1.5 mm.

4. The preparation method according to claim 1, characterized in that: After the dispersion of the liquid metal nanoparticles is sprayed on the transparent substrate, a liquid metal nanoparticle film is formed; the thickness of the liquid metal nanoparticle film is 1 μm to 20 μm.

5. The preparation method according to claim 1, characterized in that: Placing the target substrate on a displacement stage, placing the processing material on a side of the target substrate away from the displacement stage, and a side of the processing material sprayed with the liquid metal nanoparticles facing a side of the target substrate away from the displacement stage; Preferably, the target substrate is selected from any one of quartz glass, silicon wafer, sapphire, PI film, and PDMS.

6. The preparation method according to claim 1, characterized in that: The laser is incident from a side of the processing material on which the liquid metal nanoparticles are not sprayed; Preferably, the laser processing method is line-by-line scanning; the laser scanning path planning is: designing a processing graphic, filling the scanning lines into the graphic, scanning the outline of the graphic after completing the internal scanning of the graphic, and converting the final scanning path into a processing file that can be recognized by the processing equipment.

7. The preparation method according to claim 1, characterized in that: The laser is a nanosecond laser.

8. The preparation method according to claim 7, characterized in that: The wavelength of the laser is 532nm-1650nm, the repetition frequency is 2kHz-20kHz, the pulse width is less than 100ns, and the single pulse energy required for processing is greater than 0.3mJ; Preferably, the scanning speed of the laser is 50 mm / s to 3000 mm / s, the scanning range is -25° to 25°, the spot diameter is 30 μm to 44 μm, and the scanning line distance is 30 μm to 44 μm.

9. The liquid metal film obtained according to the preparation method according to any one of claims 1 to 8.

10. A flexible conductive device, characterized in that: The flexible conductive device comprises the liquid metal film according to claim 9.

Images