Three-dimensional self-driven underwater airflow control system, preparation method and application

Abstract

The invention discloses a three-dimensional self-driven underwater air flow control system, and relates to the technical field of underwater air flow control, and the underwater air flow control system provided by the invention can realize transmission and control of trace gas at a microscopic level, so that new functions and applications which cannot be realized by some traditional liquid microfluids can be realized. Aiming at the defects of a two-dimensional airflow control system, the invention provides a new strategy for constructing a three-dimensional self-driven underwater airflow control system by using Laplace pressure difference in bubbles in combination with a Chinese traditional weaving technology and a super-hydrophobic metal wire. The two ends of the super-hydrophobic metal wires are curled into disc shapes with different sizes by utilizing a Chinese traditional weaving technology, and when the formed framework is immersed into water, the disc structures and the connecting metal wires are wrapped by a layer of retained air, so that a communicated airflow control system is formed.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater airflow control, and in particular is a three-dimensional self-driven underwater airflow control system. Background Art

[0002] Microfluidics uses microchannels to process or manipulate trace amounts of liquids and has been widely used in modern science and technology, such as high-throughput chemical testing, biological analysis, cell manipulation, drug screening, and medical monitoring and inspection. Traditional microfluidics mainly focuses on processing and manipulating liquids, but rarely pays attention to gases. Since many chemical reactions, analyses, and detection objects involve gases, the delivery and processing of trace gases is a technology with great potential. Inspired by the biological characteristics of lotus leaves and other natural organisms, researchers use various special wettability functional surfaces to manipulate droplets or bubbles, and use special wettability surfaces in microfluidic systems to manipulate microfluidics; special wettability surfaces show different water contact angles (WCA) according to the liquid on the solid surface. The WCA in the range of 0°<θ<10°, 10°<θ<90°, 90°<θ<150°, and 150°<θ<180° can be defined as superhydrophilic, hydrophilic, hydrophobic, and superhydrophobic, respectively. It is worth noting that hydrophilicity usually corresponds to aerophobicity, and hydrophobicity corresponds to aerophilicity. Similarly, the wettability behavior between solids and gases can be defined as superaerophobic, aerophobic, aerophilic, and superaerophilic, respectively. Special wettability surfaces can not only accurately manipulate droplets and gases, but also efficiently mix fluids, improve analysis efficiency and accuracy, and have the advantages of reducing the energy consumption and cost of microfluidic systems. Therefore, special wettability surfaces can play an important role in the field of microfluidics.

[0003] In recent years, the advantages of a wide range of processable materials and fine design of micro-nano structures have made femtosecond lasers an effective tool for preparing various super-wetting microstructure surfaces; therefore, using femtosecond lasers to regulate the wettability of material surfaces to design underwater microfluidic systems has broad development prospects; and the patent with publication number CN209445061U provides a gas transmission system, including: a gas box, having multiple gas storage chambers for storing gas; multiple chambers; a gas transmission tube, one end of which is connected to the multiple gas storage chambers, and the other end is connected to the multiple chambers, the gas transmission tube includes: multiple first gas transmission tubes, one end of the multiple first gas transmission tubes is connected to the multiple gas storage chambers one by one; a second gas transmission tube, one end of the second gas transmission tube is connected to the other end of the multiple first gas transmission tubes, and the other end of the second gas transmission tube is connected to the multiple chambers, and the inner diameter of at least a part of the second gas transmission tube is larger than the inner diameter of the first gas transmission tube; however, its structure is complex and transmission is inconvenient; based on this, a solution is provided. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art; To this end, the present invention proposes a three-dimensional self-driven underwater airflow control system, comprising: at least one input disk of diameter a; At most one output disk with diameter > a or at least one output disk with diameter a; The output disk is connected to at least one input disk via a connecting line; The input disk, output disk and connecting wire are all made of strands formed by twisting a plurality of metal wires with each other; The surface of the wire is covered with laser-induced nanostructures.

[0005] Furthermore, the strand is made of two mutually twisted metal wires; the metal wires are made of 304 stainless steel and have a diameter of 100-500 μm.

[0006] Furthermore, the input disk and the output disk are in a planar spiral shape formed by winding the strands.

[0007] Further, the nanostructure is obtained by the following treatment: Clean the strands with alcohol and deionized water for ten minutes each; Then, a femtosecond laser is used to ablate the surface of the strands, thereby forming a covering nanostructure on the surface of the strands.

[0008] A method for preparing a three-dimensional self-driven underwater airflow control system, the method specifically comprising the following steps: Laser ablation is performed on the surface of a strand obtained by winding a plurality of metal wires, and then the ablated substrate is connected to a polyimide double-sided tape and heated at a constant temperature of 75°C-300°C and a heating time of 10-300 minutes; crimping the strands into at least one input disk with a diameter a, and at most one output disk with a diameter > a or at least one output disk with a diameter a; The output disk is connected to at least one input disk via strands.

[0009] Furthermore, the strand is obtained by winding two metal wires made of 304 stainless steel with each other, and the diameter of the metal wire is 100-500 μm.

[0010] An application of a three-dimensional self-driven underwater gas flow control system, wherein the aforementioned gas flow control system is used to perform three-dimensional transmission of gas underwater.

[0011] Furthermore, when there is an output disk with a diameter greater than a, gas is input from at least one input disk and partially or completely transmitted to the output disk with a diameter greater than a through the strands. Here, partially refers to the transmitted gas being at least more than half of the original gas, and the transmitted gas increases as the diameter of the output disk increases until it is completely transmitted.

[0012] Further, when the diameters of the input disk and the output disk are the same, the gas received by the input disk is evenly divided between the input disk and the output disk via the strands.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The underwater gas flow control system provided by the present invention can realize the transmission and manipulation of trace gases at the microscopic level, so it can realize some new functions and applications that cannot be realized by traditional liquid microfluidics. In view of the shortcomings of the two-dimensional gas flow control system, a new strategy is proposed to combine traditional Chinese weaving technology and super-hydrophobic metal wires to construct a three-dimensional self-driven underwater gas flow control system using the Laplace pressure difference in bubbles. The two ends of the super-hydrophobic metal wire are curled into discs of different sizes using traditional Chinese weaving technology, and when the skeleton formed is immersed in water, the disc structure and the connecting metal wire will be wrapped by a layer of trapped air, thereby forming a connected gas flow control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the femtosecond laser processing system mentioned in the present invention; Figure 2-a Schematic diagram of femtosecond laser processing of twisted stainless steel wire; Figure 2-b SEM images of laser-induced microstructures on the surface of twisted stainless steel wire; Figure 2-c Schematic diagram of the contact state between the underwater airflow control system of the present invention and the water environment; Figure 3-a A top view of the skeleton structure of the airflow control system prepared by traditional Chinese weaving technology; Figure 3-b A diagram showing the change in gas transmission state of an underwater gas flow control system structure connected in an arch shape; Figure 3-c A diagram showing the gas transmission state changes of a spirally connected underwater gas flow control system structure; Figure 3-d This is a graph showing the change of gas shape in the input / collection area over time during the gas self-driven transport process; Figure 3-e is a graph showing the change of gas volume in the input area over time; Figure 3-f Schematic diagram of the effect of the length (L) of the connecting line between the collection area and the input area on the gas transmission process; Figure 3-gSchematic diagram of the effect of the area ratio (η) of the collection area to the input area on the gas transmission process; Figure 3-h Schematic diagram showing the physical mechanism of gas self-driven transmission in the designed underwater gas flow control system; Figure 3-i A 45° tilted view of the airflow control system skeleton structure prepared using traditional Chinese weaving technology; Figure 4-a It is a diagram showing the change in the anti-buoyancy gas transmission state when the gas flow control system is tilted downward; Figure 4-b It is a diagram showing the state change of self-driven gas transmission along the arched connecting line; Figure 4-c It is the state change diagram of self-driven gas transmission along the spiral connection line; Figure 4-d This is a diagram showing the state changes of independent gas transmission when two staggered transmission lines are not in contact; Figure 4-e It is a diagram showing the change of gas transmission state when different gas flow control systems are connected together through simple contact; Figure 4-f It is a state change diagram of an underwater gas flow control system for gas separation; Figure 4-g It is a state change diagram of the underwater gas flow control system for gas merging; Figure 4-h Diagram of the state changes of the micro-reaction between hydrogen and oxygen to be realized on a simple underwater gas flow control design. DETAILED DESCRIPTION

[0015] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0016] See also Figure 1 , Figure 2-a , Figure 2-b , Figure 2-c As shown; the present application provides a three-dimensional self-driven underwater airflow control system, comprising: at least one input disk of diameter a; At most one output disk with diameter > a or at least one output disk with diameter a; The output disk is connected to at least one input disk via a connecting line; The input disk, output disk and connecting wire are all made of strands formed by twisting a plurality of metal wires with each other; The surface of the wire is covered with laser-induced nanostructures.

[0017] Of course, the present application also provides a method for preparing a three-dimensional self-driven underwater airflow control system, which specifically includes the following steps: Step 1, twist two thin metal wires made of 304 stainless steel with a diameter of 100-500 μm together to form a twisted metal wire and wash them with alcohol and deionized water for ten minutes respectively; Step 2: Figure 1 As shown in FIG. 1 , a femtosecond laser processing system is used to perform femtosecond laser ablation processing on the surface of a twisted metal wire. During the laser ablation process, the twisted metal wire will gradually rotate, so that the entire surface of the metal wire is covered with a laser-induced nanostructure. The femtosecond laser processing parameters are a scanning power of 50-500mw, a scanning speed of 1-20mm / s, and a scanning spacing of 0.01-0.04mm. The processing process is as follows Figure 2-a As shown; Step 3, connect the twisted metal wire processed by femtosecond laser to the PI double-sided tape and send them into an electric constant temperature drying oven for heating treatment. The PI double-sided tape is a polyimide double-sided tape. The heating parameters are a heating temperature of 75°C-300°C and a heating time of 10-300min. Step 4: Use traditional Chinese weaving technology to curl the two ends of the twisted metal wire that has been processed by femtosecond laser and heated into discs with different radii, leaving a connecting line at a certain distance between the two discs; Of course, in the specific implementation, the discs with diameters of 3 mm and 8 mm can be used, and the distance between the connecting lines of the two discs is 20 mm. Figure 3-a , Figure 3-i shown.

[0018] Of course, the three-dimensional self-driven underwater gas flow control system provided by the present application can be applied to self-driven gas transmission; like Figure 3-b As shown, the gas transmission capability of the designed basic gas flow control system in water medium is demonstrated; The circular area on the left of the basic airflow control system is the input area, and the radius r1 of the input area is 1.5 mm. The circular area on the right is the collection area, and the radius r2 of the collection area is 4 mm. The input area is the input disk mentioned above, and the collection area is the output disk mentioned above. like Figure 3-d As shown, when the bubble is released into the input area, its volume decreases rapidly; In addition, the gas gradually bulges in the collection area, indicating that the gas has been successfully transferred from the input area to the target area along the fine superhydrophobic connection line; when the gas of the first bubble is completely transported away, the gas of the subsequently injected bubble can also be successfully transported to the large circular area, and the gas in the collection area continues to expand; the entire gas transport process is spontaneous and does not require additional energy input; on the contrary, Figure 3-c As shown in the figure, when the diameter of the input circular area is larger than the diameter of the collection area and the gas is added to the larger circular area, the injected gas cannot be transported; these results indicate that under the action of the Laplace pressure difference inside the bubble, the gas can be self-driven and transported from the smaller circular area to the larger circular area along the superhydrophobic connecting line; like Figure 3-d and Figure 3-e As shown, during the gas self-driven transport process, the volume of gas injected into the input area gradually decreases with time until it approaches zero, while the volume of gas in the collection area gradually increases; Figure 3-g The different ratios of the collection area to the input area ( ) gas transmission process of the gas flow control system. The larger the area difference between the collection area and the input area, that is, the larger the ratio, the more conducive it is to the spontaneous transmission of the gas. The length L of the connecting line between the input area and the collection area also has an important influence on the gas transmission process, such as Figure 3-f The longer the transmission distance, the slower the gas flow rate because the transmission process needs to overcome more fluid resistance.

[0019] Figure 3-h The physical mechanism of self-driven gas transport in the designed gas flow control system is revealed. In water, a thin layer of air surrounds the superhydrophobic wire skeleton because water cannot wet the laser-induced superhydrophobic microstructure. The trapped gas channel along the gap of the twisted wire connects the trapped air film above the input and collection areas. When a small bubble is injected into the input area, the gas will be confined to the superhydrophobic / superhydrophilic circular substrate due to the limiting effect of the wettability difference. The gas forms a hemispherical shape in this area, and the bottom of the bubble overlaps with the disk of the twisted wire. There is usually a pressure difference on both sides of the gas-liquid interface, which is called Laplace pressure. When a small bubble is sent into the input area of ​​the designed gas flow control system, there is a pressure difference between the bubble in the input area and the trapped air film in the collection area. Due to the existence of the connecting gas channel, the gas with higher internal pressure will flow along the pressure gradient to the area with the lowest pressure until the system reaches fluid dynamic equilibrium, that is, the pressure is equal. Therefore, the Laplace pressure inside the small bubble can provide a driving force for the designed underwater gas flow control device.

[0020] Self-driven gas transport enables the designed gas flow control structure to realize complex gas transport functions in three-dimensional space; the specific applications are as follows: 1. Gas delivery on demand: By tilting the basic gas flow control device with a connection line of 20 mm downward, the gas injected into the upper input area can also be spontaneously transferred to the lower collection area, such as Figure 4-a , the entire downward transport process overcomes the buoyancy of the gas. Even if the 30mm connecting line is bent vertically into a three-dimensional arch, such as Figure 4-b Or twist the 80mm connecting wire into a more complex spiral shape, such as Figure 4-c , the gas flow control system still supports spontaneous gas delivery. Due to the characteristics of three-dimensional gas transmission, the two staggered gas transmission lines of the basic gas flow control system and the gas flow control system with curved and raised connecting lines can independently transmit gas without interfering with each other as long as they do not touch, that is, one line passes through the other line from above. Figure 4-d As shown in the figure, the gas injected into area A1 is eventually transferred to area A2; then the gas injected into area B1 flows completely to area B2. This function of transferring gas from one side of the gas pipeline to the other is difficult to achieve with a two-dimensional gas flow control system; Two airflow control systems with curved ridges can also be connected together by simple contact. Figure 4-e , two staggered gas flow control systems with an angle of about 90° are superimposed by making the middle of their connecting lines touch each other. One of the gas flow control systems has two small circular areas with the same diameter of 3mm at both ends, A1 and A2; while the other system has a small circular area B1 with a diameter of 3mm and a large circular area B2 with a diameter of 8mm. When small bubbles are injected into the A1 area, the gas will eventually bulge in the B2 area, which shows that the gas can be transmitted in different underwater gas flow control systems, A1→B2.

[0021] 2. Gas splitting and gas merging; By combining different gas flow control structures, a variety of gas transport functions can be achieved. For example, Figure 4-f The stacked system consisting of two identical gas flow control units is shown. Both units consist of two small round ends with a diameter of 3mm and a ridged connecting line with a spacing of 20mm. This combined system has the ability to split the gas. When a bubble is injected into any of the circular areas, the gas is transported to the other circular areas and bulges evenly. The input gas is successfully divided into four equal parts. Figure 4-g As shown in the figure, if several small circular areas with a diameter of 3 mm and a 15 mm raised connection line are connected to a large circular area with a diameter of 8 mm, the gas injected into the bubbles in each small circular area will eventually flow to the largest circular area, so that the input gas from different directions will be gathered together, and the system can achieve gas merging or gas collection. The system can also achieve the mixing of different types of gases by injecting these gases into different input areas.

[0022] 3. Application of gas / gas microchemical reaction based on gas flow control; As a proof-of-concept application, Figure 4-h An underwater gas flow control system consisting of two small circular areas with a diameter of 3 mm, a large circular area with a diameter of 8 mm, and a connecting line of 15 mm between the large and small circles was demonstrated to achieve micro-reactions between different gases.

[0023] Step 1. Inject four 10μL H2 bubbles into the small circle input area on the left. The hydrogen in the bubbles will be transferred to the collection area of ​​the system, which is the large circle area in the figure.

[0024] Step 2: Inject two 10μL O2 bubbles into the small circle input area on the right in succession. Oxygen will also flow to the collection area, and an air mass composed of hydrogen and oxygen will be formed in the collection area.

[0025] Step 3: Ignite the mixed gas with the electric flame generated by the piezoelectric ceramic, and the mixed gas instantly explodes. This micro-reaction quickly consumes hydrogen and oxygen, 2H2+O2→2H2O, causing the mixed gas bubbles to collapse sharply.

[0026] This indicates that the prepared gas flow control system can be used for gas / gas microchemical reactions.

[0027] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A three-dimensional self-driven underwater airflow control system, characterized in that: include: at least one input disk of diameter a; At most one output disk with diameter > a or at least one output disk with diameter a; The output disk is connected to at least one input disk via a connecting line; The input disk, output disk and connecting wire are all made of strands formed by twisting a plurality of metal wires with each other; The surface of the wire is covered with laser-induced nanostructures.

2. A three-dimensional self-driven underwater airflow control system according to claim 1, characterized in that: The strands are made of two metal wires twisted together; the metal wires are made of 304 stainless steel and have a diameter of 100-500μm.

3. A three-dimensional self-driven underwater airflow control system according to claim 1, characterized in that: The input disk and the output disk are in a planar spiral shape formed by winding the strands.

4. A three-dimensional self-driven underwater airflow control system according to claim 1, characterized in that: The nanostructures were obtained by: Clean the strands with alcohol and deionized water for ten minutes each; Then, a femtosecond laser is used to ablate the surface of the strands, thereby forming a covering nanostructure on the surface of the strands.

5. A method for preparing a three-dimensional self-driven underwater airflow control system, characterized in that: The method specifically comprises the following steps: Laser ablation is performed on the surface of a strand obtained by winding a plurality of metal wires, and then the ablated substrate is connected to a polyimide double-sided tape and heated at a constant temperature of 75°C-300°C and a heating time of 10-300 minutes; crimping the strands into at least one input disk with a diameter a, and at most one output disk with a diameter > a or at least one output disk with a diameter a; The output disk is connected to at least one input disk via strands.

6. The method for preparing a three-dimensional self-driven underwater airflow control system according to claim 5, characterized in that: The strands are obtained by winding two 304 stainless steel wires with each other, and the diameter of the wires is 100-500 μm.

7. Application of a three-dimensional self-driven underwater airflow control system, characterized in that: The system according to any one of claims 1 to 4 is used for three-dimensional transmission of gas underwater.

8. The application of a three-dimensional self-driven underwater airflow control system according to claim 7, characterized in that: When there is an output disk with a diameter > a; The gas is input from at least one input disk and is partially or completely transmitted to the output disk with a diameter > a through the strands.

9. Application of a three-dimensional self-driven underwater airflow control system according to claim 8, characterized in that: When there is an output disk with a diameter greater than a, gas is input from at least one input disk and partially or completely transmitted to the output disk with a diameter greater than a through the strands. Here, partially means that the transmitted gas is at least more than half of the original gas, and as the diameter of the output disk increases, the transmitted gas increases until it is completely transmitted.

10. Application of a three-dimensional self-driven underwater airflow control system according to claim 8, characterized in that: When the diameters of the input disk and the output disk are the same, the gas received by the input disk is evenly divided between the input disk and the output disk through the strands.

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