A durable structure for transporting low surface energy droplets processed by laser and a method for preparing the same

Abstract

The present invention discloses a durable structure for transporting low surface energy droplets processed by laser and a preparation method thereof, comprising: a substrate thin plate, on which a primary wedge-shaped channel is processed, one end of the primary wedge-shaped channel is a divergent end, and the other end is a convergent end, and both sides of the primary wedge-shaped channel are processed with clamps; a secondary wedge-shaped groove array, which is nested inside the primary wedge-shaped channel, and there are multiple wedge-shaped protrusions of the same shape and size between the secondary wedge-shaped groove arrays, and the convergence direction of the wedge-shaped protrusions is opposite to the convergence direction of the primary wedge-shaped channel, and the wedge-shaped protrusions are evenly distributed in the first wedge-shaped channel in the horizontal and vertical directions. The durable structure of the present invention can realize the efficient long-distance transportation of low surface energy droplets in air, strong acid, strong alkali, and water environments, and can be assembled and expanded into a two-dimensional or three-dimensional low surface energy droplet long-distance transportation and separation device, and has excellent properties of acid and alkali resistance and wear resistance. This durable and practical structure for transporting low surface energy droplets is applied to biomedicine, oil-water separation, microfluidics and other fields.

Description

Technical Field

[0001] The invention relates to the field of laser scanning and cutting processing, microfluidics, droplet transport and separation technology, and in particular to a durable structure for transporting low-surface energy droplets processed by laser and a preparation method thereof. Background Art

[0002] Self-transport of droplets without external energy input has a wide range of applications in biomedicine, oil-water separation, microfluidics and other fields. Studies have shown that special wettability gradient surfaces can enable spontaneous transport of droplets. However, the low contact angle of low surface energy droplets makes it difficult to control their movement path. Although the contact angle of low surface energy droplets can be increased by chemically modifying the substrate surface, there are disadvantages such as poor durability and fluoride pollution of the environment. In addition, asymmetric structure surfaces have also been proven to be used to drive the spontaneous transport of droplets. In recent years, three-dimensional asymmetric structures such as bionic fish bones and rice leaves have been reported to achieve directional transport of oil droplets using the driving force generated by their structural gradients. However, these three-dimensional asymmetric structures generally have disadvantages such as high difficulty in preparation and low transport efficiency.

[0003] With the vigorous development of industries such as biomedicine, drug purification, and pollution control, the efficient transportation of low surface energy droplets has attracted the attention of more and more researchers. However, most of the structures reported so far for transporting low surface energy droplets have the disadvantages of being unable to achieve self-transport of droplets in complex environments, limited droplet transportation distance, and poor durability. In view of the shortcomings of existing structures, it is urgent to develop a durable structure that can be used to transport low surface energy droplets in multiple environments. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these objects and other advantages of the present invention, a method for preparing a durable structure for transporting low surface energy droplets in multiple environments by laser cutting is provided, the steps of which are as follows:

[0006] A femtosecond laser is used to process an array of secondary wedge-shaped grooves of the same shape and size and uniformly distributed in the horizontal and vertical directions on a substrate sheet. The laser beam of the femtosecond laser is perpendicular to the surface of the substrate sheet and scans the surface of the processing area line by line in a parallel manner. After multiple scans, alternating secondary wedge-shaped grooves and wedge-shaped protrusions are obtained. The secondary wedge-shaped grooves and wedge-shaped protrusions form a wedge-shaped channel. Finally, the rectangular thin sheet containing the scanned part is cut off to form a durable structure for transporting low surface energy droplets.

[0007] Preferably, the spot diameter of the laser beam is 15-25 μm, the pulse energy is 200-250 mW, the scanning speed is 5-10 mm / s, the scanning interval is 15-25 μm, and the number of scans is 3-10 times.

[0008] Preferably, the processing area is a periodic wedge-shaped area.

[0009] Preferably, the surface of the obtained processed area is covered with micro-nano structures generated after laser beam scanning and is super oleophilic.

[0010] A durable structure for transporting low surface energy droplets in multiple environments, comprising:

[0011] A substrate thin plate, on which a primary wedge-shaped channel is processed, one end of the primary wedge-shaped channel is a divergent end, and the other end is a convergent end, and two sides of the primary wedge-shaped channel are processed with clamping plates;

[0012] A secondary wedge-shaped groove array is nested inside the primary wedge-shaped channel, and a plurality of wedge-shaped protrusions of the same shape and size are arranged between the secondary wedge-shaped groove arrays, and the convergence direction of the wedge-shaped protrusions is opposite to the convergence direction of the primary wedge-shaped channel, that is, the tips of the wedge-shaped protrusions face the divergent end of the primary wedge-shaped channel; the wedge-shaped protrusions are evenly distributed in the first-level wedge-shaped channel in both horizontal and vertical directions, and the number of the wedge-shaped protrusions decreases row by row from the divergent end to the convergent end of the primary wedge-shaped channel.

[0013] Preferably, the substrate sheet is made of polytetrafluoroethylene.

[0014] Preferably, the thickness of the substrate sheet is 0.5 to 1 mm.

[0015] Preferably, the height of the first-level wedge-shaped channel is 13-14 mm, the length of the divergent end is 2080-2120 μm, the length of the convergent end is 208-212 μm, and the depth of the clamping plates on both sides is 100-300 μm; the second-level wedge-shaped groove arrays are the same depth as the clamping plates on both sides; the bottom edge length of the wedge-shaped protrusion is 190-210 μm, the height is 1945-2145 μm, the lateral spacing is 0.24-0.42 mm, and the lateral and longitudinal spacing ratio is 7:45.

[0016] An application of a durable structure that can be used to transport low surface energy droplets in multiple environments, characterized in that the durable structure is used to achieve efficient long-distance transportation of low surface energy droplets in air, strong acid, strong alkali, and water environments, and the transportation direction of the low surface energy droplets on the durable structure is from the divergent end of the primary wedge-shaped channel to the convergent end.

[0017] The present invention has at least the following beneficial effects:

[0018] The PTFE sheet used in the present invention has the advantages of flexibility, easy processing, stable chemical properties, low friction coefficient, acid and alkali corrosion resistance, high temperature resistance, low surface energy, etc., so that the processed structure has good acid and alkali corrosion resistance and wear resistance, and can be used in complex and harsh environments.

[0019] The present invention adopts femtosecond laser direct writing technology to process a two-level wedge-shaped structure in one step, and the preparation process is simple and easy to implement without polluting the environment.

[0020] The structure of the present invention introduces a two-level wedge structure, which cleverly superimposes the driving force generated by the double wettability gradient and the driving force generated by the structural gradient, thereby achieving efficient transportation of low surface energy droplets, and the speed of transporting n-octane in the air is as high as 115.7 mm / s.

[0021] The durable structure designed by the present invention can be used to transport low surface energy droplets in multiple environments. It can achieve efficient long-distance transportation of low surface energy droplets in air, strong acid, strong alkali, and water environments, and can be flexibly assembled and expanded into two-dimensional and three-dimensional low surface energy droplet long-distance transportation and separation devices. It can be used for efficient transportation and separation of low surface energy droplets in the air, extraction and detection of oil pollutants in wastewater, removal of oil in the pharmaceutical process, etc. These applications are of great significance to the development of biomedicine, oil-water separation, microfluidics and other fields.

[0022] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the processing of a durable structure that can be used to transport low surface energy droplets in multiple environments according to the present invention;

[0024] Figure 2 A schematic diagram of a durable structure of the present invention that can be used to transport low surface energy droplets in multiple environments;

[0025] Figure 3 This is a scanning electron microscope morphology image of the laser unprocessed area of ​​the durable structure of the present invention that can be used to transport low surface energy droplets in multiple environments;

[0026] Figure 4 This is a scanning electron microscope morphology image of the concave surface of the durable structure that can be used to transport low surface energy droplets in multiple environments after multiple laser processing of the present invention;

[0027] Figure 5 This is a scanning electron microscope morphology image of the side surface of the durable structure of the present invention that can be used to transport low surface energy droplets in multiple environments after multiple laser processing;

[0028] Figure 6The durable structure of the present invention can be used for transporting low surface energy droplets in multiple environments to achieve efficient transportation of low surface energy droplets in an air environment;

[0029] Figure 7 The durable structure of the present invention can be used to transport low surface energy droplets in multiple environments to transport heavy oil against gravity in water environments;

[0030] Figure 8 The durable structure of the present invention can be used to transport low surface energy droplets in multiple environments to transport heavy oil against gravity in saturated acetic acid solution;

[0031] Fig. 9 The durable structure of the present invention can be used to transport low surface energy droplets in multiple environments to transport heavy oil against gravity in a saturated sodium hydroxide solution;

[0032] Fig.10 This is a schematic diagram of the low surface energy droplet long-distance transport device in Example 5 realizing long-distance transport of low surface energy droplets along a complex path in a water environment;

[0033] Fig.11 It is a schematic diagram of a durable structural wear test device that can be used for transporting low surface energy droplets in multiple environments according to the present invention;

[0034] Fig.12 The test results of the wear resistance of the durable structure of the present invention that can be used to transport low surface energy droplets in multiple environments;

[0035] Fig.13 is the transport performance of n-octane on the non-depth super-oleophilic wedge structure processed in Comparative Example 1;

[0036] Fig.14 The transport performance of n-octane on the deep super-oleophilic wedge structure processed in Comparative Example 2;

[0037] Fig.15 The transport performance of n-octane on the durable structure processed in Example 1 that can be used to transport low surface energy droplets in multiple environments. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0039] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0040] The present invention uses femtosecond laser direct writing technology to perform subtractive processing on PTFE sheets (see Figure 1 ) and fabricated a durable structure that can be used to transport low-surface-energy droplets in multiple environments (see Figure 2 ), whose structure includes:

[0041] A polytetrafluoroethylene sheet, on which a primary wedge-shaped channel is processed, one end of the primary wedge-shaped channel is a divergent end 3, and the other end is a convergent end 4, and two sides of the primary wedge-shaped channel are processed with clamping plates 1;

[0042] A secondary wedge-shaped groove array 2 is nested inside the primary wedge-shaped channel, and a plurality of wedge-shaped protrusions 5 of the same shape and size are arranged between the secondary wedge-shaped groove array 2, and the convergence direction of the wedge-shaped protrusions 5 is opposite to the convergence direction of the primary wedge-shaped channel, that is, the tip of the wedge-shaped protrusion 5 faces the divergent end 3 of the primary wedge-shaped channel; the wedge-shaped protrusions 5 are evenly distributed in the first-level wedge-shaped channel in both horizontal and vertical directions, and the number of the wedge-shaped protrusions 5 decreases row by row from the divergent end 3 to the convergent end 4 of the primary wedge-shaped channel.

[0043] Polytetrafluoroethylene (PTFE) itself has excellent physical and chemical properties. Laser processing introduces micro-nano structures to enhance its surface lipophilicity (see Figure 3 , Figure 4 , Figure 5 ), the present invention introduces a two-level wedge structure, which cleverly superimposes the driving force generated by the dual wettability gradient and the driving force generated by the structural gradient, thereby achieving efficient long-distance transport of low surface energy droplets in multiple environments.

[0044] The technical solution proposed by the present invention is described in more detail below with several specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] A durable structure of the present embodiment that can be used to transport low surface energy droplets in multiple environments is arranged on a PTFE sheet with a thickness of 0.5 mm. The durable structure includes a primary wedge-shaped channel, in which a secondary wedge-shaped groove array 2 is nested. The primary wedge-shaped channel is 13.5 mm high, the divergent end 3 is 2080 μm long, the convergent end 4 is 208 μm long, and the depth of the clamping plates 1 on both sides is 190 μm. The secondary wedge-shaped groove arrays 2 are the same depth as the clamping plates 1 on both sides, and the secondary wedge-shaped groove arrays 2 form a shape of size The same wedge-shaped protrusion 5 has a base length of 190 to 210 μm, a height of 1945 to 2045 μm, a lateral spacing of 0.3 mm, a lateral and longitudinal spacing ratio of 7:45, and a convergence direction of the wedge-shaped protrusion 5 opposite to that of the primary wedge-shaped channel, that is, the tip of the wedge-shaped protrusion 5 faces the divergent end 3 of the primary wedge-shaped channel. The wedge-shaped protrusions 5 are evenly distributed in the primary wedge-shaped channel in the horizontal and vertical directions, and the number of the wedge-shaped protrusions 5 decreases row by row from the divergent end 3 to the convergent end 4 of the primary wedge-shaped channel.

[0047] The method for preparing a durable structure that can be used to transport low surface energy droplets in multiple environments of this embodiment includes the following steps:

[0048] A femtosecond laser with a spot diameter of 18μm and a pulse energy of 240mW was used to process a secondary wedge-shaped groove array with the same shape and size and uniform distribution in the horizontal and vertical directions on a 0.5mm thick PTFE sheet. The laser beam of the femtosecond laser was perpendicular to the surface of the substrate sheet and scanned line by line in a parallel manner on the surface of the processing area. The scanning interval was 20μm and the scanning speed was 10mm / s. After 7 scans, alternating secondary wedge-shaped grooves and wedge-shaped protrusions were obtained, and finally a rectangular sheet containing the scanned part was cut off.

[0049] See also Figure 6 In order to verify that the durable structure of the present embodiment that can be used to transport low surface energy droplets in multiple environments can efficiently transport low surface energy droplets in an air environment, the durable structure at different inclination angles was tested. The results showed that the transport speed decreased with the increase of the inclination angle. When the inclination angles were 0°, 30°, 60°, and 90°, the transport speeds of n-octane (surface tension of 21.14 mN / m) were 115.7 mm / s, 83.6 mm / s, 74 mm / s, and 57.94 mm / s, respectively. This verifies that the durable structure of the present embodiment that can be used to transport low surface energy droplets in multiple environments has the ability to efficiently transport low surface energy droplets, and can be used to efficiently transport and separate low surface energy droplets in the air.

[0050] Example 2

[0051] The durable structure of the present embodiment can be used to transport low surface energy droplets in multiple environments. It is arranged on a PTFE sheet with a thickness of 0.5 mm. The durable structure includes a primary wedge-shaped channel, and a secondary wedge-shaped groove array is nested inside the primary wedge-shaped channel. The primary wedge-shaped channel is 13.5 mm high, the divergent end length is 2100 μm, the convergent end length is 210 μm, and the depth of the two side clamps is 200 μm. The secondary wedge-shaped groove arrays are all the same depth as the two side clamps, and a large shape is formed between the secondary wedge-shaped groove arrays. The invention relates to a wedge-shaped protrusion of the same size, wherein the base length of the wedge-shaped protrusion is 190 to 210 μm, the height is 2045 to 2145 μm, the lateral spacing is 0.3 mm, the lateral and longitudinal spacing ratio is 7:45, the convergence direction of the wedge-shaped protrusion is opposite to the convergence direction of the primary wedge-shaped channel, that is, the tip of the wedge-shaped protrusion is toward the divergent end of the primary wedge-shaped channel, the wedge-shaped protrusions are evenly distributed in the first-level wedge-shaped channel in the horizontal and vertical directions, and the number of the wedge-shaped protrusions decreases row by row from the divergent end to the convergent end of the primary wedge-shaped channel.

[0052] This embodiment can be used for the preparation method of a durable structure for transporting low surface energy droplets in multiple environments, comprising the following steps:

[0053] A femtosecond laser with a spot diameter of 18μm and a pulse energy of 250mW was used to process a secondary wedge-shaped groove array with the same shape and size and uniform distribution in the horizontal and vertical directions on a 0.5mm thick PTFE sheet. The laser beam of the femtosecond laser was perpendicular to the surface of the substrate sheet and scanned line by line in a parallel manner on the surface of the processing area. The scanning interval was 20μm and the scanning speed was 10mm / s. After 7 scans, alternating secondary wedge-shaped grooves and wedge-shaped protrusions were obtained, and finally a rectangular sheet containing the scanned part was cut off.

[0054] See also Figure 7 In order to verify that the durable structure of this embodiment that can be used to transport low surface energy droplets in multiple environments can transport low surface energy droplets in an aqueous environment, the durable structure was placed in an aqueous environment, and 3 μL of 1,2-dichloroethane (surface tension of 34.5 mN / m) was dropped on the divergent end of the primary wedge-shaped groove channel through a syringe. In the aqueous environment, the durable structure achieved the counter-gravity transport of heavy oil at a transport speed of 15.88 mm / s, verifying that the durable structure that can be used to transport low surface energy droplets in multiple environments obtained by this embodiment has the ability to transport low surface energy droplets in an aqueous environment, and can be used for the extraction and detection of oil pollutants in wastewater.

[0055] Example 3

[0056] The durable structure of this embodiment can be used to transport low surface energy droplets in multiple environments, and its structure and processing method are the same as those of Example 2.

[0057] See also Figure 8In order to verify that the durable structure of this embodiment that can be used to transport low surface energy droplets in multiple environments can realize the transportation of low surface energy droplets in a strong acid environment, the durable structure was placed in a saturated acetic acid solution, and 3 μL of 1,2-dichloroethane (surface tension of 34.5 mN / m) was dropped on the divergent end of the primary wedge-shaped channel through a syringe. In the harsh acid environment, the durable structure realized the counter-gravity transportation of heavy oil, which verified that the durable structure processed in this embodiment that can be used to transport low surface energy droplets in multiple environments is resistant to acid corrosion, has the ability to transport low surface energy droplets in strong acid solutions, and can be used for the removal of oils in the pharmaceutical process.

[0058] Example 4

[0059] The durable structure of this embodiment can be used to transport low surface energy droplets in multiple environments, and its structure and processing method are the same as those of Example 2.

[0060] See also Fig. 9 In order to verify that the durable structure of this embodiment that can be used to transport low surface energy droplets in multiple environments can realize the transportation of low surface energy droplets in a strong alkaline environment, the durable structure was placed in a saturated sodium hydroxide solution, and 3 μL of 1,2-dichloroethane (surface tension of 34.5 mN / m) was dropped on the divergent end of the primary wedge-shaped channel through a syringe. In the harsh alkaline environment, the durable structure realized the counter-gravity transportation of heavy oil, which verified that the durable structure processed in this embodiment that can be used to transport low surface energy droplets in multiple environments is resistant to alkali corrosion, has the ability to transport low surface energy droplets in a strong alkaline solution, and can be used for the removal of oils in the pharmaceutical process.

[0061] Example 5

[0062] A durable structure of the present embodiment that can be used to transport low surface energy droplets in multiple environments is provided on a 0.5 mm thick PTFE sheet. The durable structure includes a primary wedge-shaped channel, in which a secondary wedge-shaped groove array is nested. The primary wedge-shaped channel is 13.5 mm high, the divergent end is 2100 μm long, the convergent end is 210 μm long, the depth of the two side clamps is 200 μm, the secondary wedge-shaped groove arrays are the same depth as the two side clamps, and a large shape is formed between the secondary wedge-shaped groove arrays. The invention relates to a wedge-shaped protrusion of the same size, wherein the base length of the wedge-shaped protrusion is 190 to 210 μm, the height is 2045 to 2145 μm, the lateral spacing is 0.3 mm, the lateral and longitudinal spacing ratio is 7:45, the convergence direction of the wedge-shaped protrusion is opposite to the convergence direction of the primary wedge-shaped channel, that is, the tip of the wedge-shaped protrusion is toward the divergent end of the primary wedge-shaped channel, the wedge-shaped protrusions are evenly distributed in the first-level wedge-shaped channel in the horizontal and vertical directions, and the number of the wedge-shaped protrusions decreases row by row from the divergent end to the convergent end of the primary wedge-shaped channel.

[0063] This embodiment, based on the above-mentioned durable structure that can be used to transport low surface energy droplets in multiple environments, assembles a low surface energy droplet long-distance transportation device, including the following steps:

[0064] (1) A femtosecond laser with a spot diameter of 18 μm and a pulse energy of 250 mW was used to process a secondary wedge-shaped groove array with the same shape and size and uniform distribution in the horizontal and vertical directions on a 0.5 mm thick PTFE sheet. The laser beam of the femtosecond laser was perpendicular to the surface of the PTFE sheet and scanned line by line in a parallel manner on the surface of the processing area. The scanning interval was 20 μm and the scanning speed was 10 mm / s. After 7 scans, the secondary wedge-shaped grooves and wedge-shaped protrusions arranged alternately were obtained, which are durable structural units that can be used to transport low surface energy droplets in multiple environments.

[0065] (2) According to the method of step (1), a plurality of durable structural units that can be used to transport low surface energy droplets under multiple environments are continuously processed on a PTFE sheet, and the convergent end of the durable structural unit is connected to the divergent end of the next adjacent durable structural unit. A processed area is cut on the PTFE sheet to obtain a strip structure including a plurality of durable structural units. The strip structure is overlapped end to end to form a Möbius ring, which is a low surface energy droplet long-distance transport device.

[0066] See also Fig.10 In order to verify that the low surface energy droplet long-distance transport device can realize the long-distance transport of low surface energy droplets along complex paths in an aqueous environment, 1,2-dichloroethane (surface tension of 34.5 mN / m) was dropped on the divergent end of the durable structural unit at the beginning of the Möbius loop through a syringe. The liquid returned to the convergent end of the durable structural unit at the end of the Möbius loop after 194.73 s, and the average transport speed reached 69.33 mm / s, verifying that the durable structure can realize the long-distance transport of low surface energy droplets along complex paths in an aqueous environment, and can be flexibly assembled and expanded into two-dimensional and three-dimensional low surface energy droplet long-distance transport and separation devices. Fig.10 The red circle in the figure marks the instantaneous position of 1,2-dichloroethane on the Möbius strip.

[0067] Example 6

[0068] The durable structure of this embodiment can be used to transport low surface energy droplets in multiple environments, and its structure and processing method are the same as those of Example 1.

[0069] See also Fig.11 In order to verify the wear resistance of the durable structure processed in this embodiment and used for transporting low surface energy droplets in multiple environments, a funnel containing 100g of fine sand was placed at a height of 20cm, and the fine sand fell vertically onto the inclined durable structure; Fig.12As shown, after 200 cycles of quicksand grinding, the durable structure still maintains an excellent transportation effect, which verifies that the durable structure has good wear resistance and can be used to transport low surface energy droplets in complex and harsh environments.

[0070] Through the verification of the above-mentioned Examples 1-6, it is confirmed that the durable structure is durable, can achieve efficient long-distance transportation of low surface energy droplets in air, strong acid, strong alkali, and water environments, and can be flexibly assembled and expanded into two-dimensional and three-dimensional low surface energy droplet long-distance transportation and separation devices.

[0071] In order to better illustrate the beneficial effects that can be achieved by a durable structure that can be used to transport low surface energy droplets in multiple environments, the technical solution of the present invention is further analyzed with several comparative examples below.

[0072] Comparative Example 1

[0073] Based on Example 1, the preparation method is different in that the processing area is the entire primary wedge-shaped channel area and only one periodic line scanning is performed to obtain a depth-free super-oleophilic wedge-shaped structure.

[0074] Comparative Example 2

[0075] Based on Example 1, the preparation method is different in that the processing area is the entire primary wedge-shaped channel area, the number of scans is the same as that in Example 1, and a deep super-oleophilic wedge-shaped structure is obtained.

[0076] See also Fig.13 , Fig.14 and Fig.15 In order to verify that the durable structure that can be used to transport low surface energy droplets in multiple environments has a more efficient low surface energy droplet transport capability, the above-mentioned Example 1 and Comparative Examples 1-2 are verified. The transport speed of n-octane in Comparative Example 1 without a deep super oleophilic wedge structure under reverse gravity is only 2.17 mm / s, which is because the driving force on the low surface energy droplets in the structural channel is only the Laplace pressure provided by the wettability difference between the processed wedge area and the unprocessed area; the transport speed of n-octane in Comparative Example 2 with a deep super oleophilic wedge structure under reverse gravity is 26.12 mm / s, which is because under the action of the splints with a certain depth on both sides, the driving force on the low surface energy droplets in the structural channel is the superposition of the Laplace pressure provided by the wettability difference between the processed wedge area and the unprocessed area and the Laplace pressure provided by the structural gradient of the splints on both sides; Fig.13 , Fig.14 and Fig.15↓g in the figure indicates the direction of gravity; Example 1 is a durable structure that can be used to transport low surface energy droplets under multiple environments. The transport speed of n-octane under reverse gravity is as high as 57.94 mm / s. This is because the driving force of the low surface energy droplets in the durable structure channel is the superposition of the Laplace pressure provided by the wettability difference between the double processed wedge area and the unprocessed area and the Laplace pressure provided by the structural gradient of the two side clamps under the synergistic effect of the clamps with a certain depth on both sides. In addition, the forward line of the liquid flow of Comparative Examples 1-Comparative Examples 2 is a symmetrical concave line, which indicates that the flow of the liquid inside the structural channel is not uniform, showing a faster driving speed along the edge, while the internal driving speed is slower. This discontinuous internal driving is the key factor limiting the efficient transportation of droplets; while the forward line of the liquid flow in Example 1 is a flat straight line, which indicates that a higher driving force is provided inside the structural channel, thereby realizing continuous and efficient transportation of droplets. Through Example 1 and Comparative Examples 1-Comparative Examples 2, it is proved that the durable structure that can be used to transport low surface energy droplets under multiple environments has an efficient low surface energy droplet transportation capability.

[0077] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0078] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A laser-processed durable structure for transporting low surface energy droplets, characterized in that: The method is prepared by a method for preparing a durable structure for transporting low surface energy droplets by laser processing, and the method for preparing a durable structure for transporting low surface energy droplets by laser processing comprises: A femtosecond laser is used to process a secondary wedge-shaped groove array with the same shape and size and uniformly distributed in the horizontal and vertical directions on a substrate thin plate. The laser beam of the femtosecond laser is perpendicular to the surface of the substrate thin plate and scans the surface of the processing area line by line in a parallel manner. After multiple scans, secondary wedge-shaped grooves and wedge-shaped protrusions arranged alternately are obtained. The secondary wedge-shaped grooves and wedge-shaped protrusions form a wedge-shaped channel. Finally, a rectangular thin sheet containing the scanned part is cut off to obtain a durable structure for transporting low surface energy droplets. The spot diameter of the laser beam is 15-25 μm, the pulse energy is 200-250 mW, the scanning speed is 5-10 mm / s, the scanning interval is 15-25 μm, and the number of scans is 3-10 times; Laser machined durable structures for transporting low surface energy droplets include: A substrate thin plate, on which a primary wedge-shaped channel is processed, one end of the primary wedge-shaped channel is a divergent end, and the other end is a convergent end, and two sides of the primary wedge-shaped channel are processed with clamping plates; A secondary wedge-shaped groove array is nested inside the primary wedge-shaped channel, and a plurality of wedge-shaped protrusions of the same shape and size are arranged between the secondary wedge-shaped groove arrays, and the convergence direction of the wedge-shaped protrusions is opposite to the convergence direction of the primary wedge-shaped channel, that is, the tip of the wedge-shaped protrusion faces the divergent end of the primary wedge-shaped channel; the wedge-shaped protrusions are evenly distributed in the primary wedge-shaped channel in both horizontal and vertical directions, and the number of the wedge-shaped protrusions decreases row by row from the divergent end to the convergent end of the primary wedge-shaped channel; The substrate sheet is made of polytetrafluoroethylene; The height of the primary wedge-shaped channel is 13-14 mm, the length of the divergent end is 2080-2120 μm, the length of the convergent end is 208-212 μm, and the depth of the clamping plates on both sides is 100-300 μm; the secondary wedge-shaped groove arrays are the same depth as the clamping plates on both sides; the bottom edge length of the wedge-shaped protrusion is 190-210 μm, the height is 1945-2145 μm, the lateral spacing is 0.24-0.42 mm, and the lateral and longitudinal spacing ratio is 7:45; The durable structure is used to achieve efficient long-distance transportation of low surface energy droplets in air, strong acid, strong alkali, and water environments. The transportation direction of the low surface energy droplets on the durable structure is from the divergent end of the primary wedge-shaped channel to the convergent end.

2. The durable structure for transporting low surface energy droplets by laser processing according to claim 1, characterized in that: The processing area is a periodic wedge-shaped area.

3. The durable structure for transporting low surface energy droplets by laser processing according to claim 1, characterized in that: The surface of the obtained processed area is covered with micro-nano structures generated after laser beam scanning and is super oleophilic.

4. The laser processed durable structure for transporting low surface energy droplets according to claim 1, characterized in that: The thickness of the substrate sheet is 0.5-1 mm.

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