A device with controllable droplet transport path and its preparation method

Abstract

The present invention discloses a device with a controllable droplet transport path and a preparation method thereof, comprising the following steps: A. partially covering the surface of a substrate with a mask; B. preparing an iron trichloride-carbon-based-fluorine source composite; C. applying the iron trichloride-carbon-based-fluorine source composite from step B to the surface of the exposed area of ​​the substrate in step A to obtain a substrate with the iron trichloride-carbon-based-fluorine source composite attached to the surface; D. processing the iron trichloride-carbon-based-fluorine source composite on the surface of the substrate in step C to obtain a substrate with a fluorine-doped graphene-iron tetroxide combination attached to the surface; E. removing the mask from the surface of the substrate in step D and cleaning it to obtain a substrate with a magnetron layer; F. depositing a lubricating layer on the surface of the substrate with the magnetron layer to obtain a device with a controllable droplet transport path. The present invention proposes a method for preparing a device with a controllable droplet transport path, and the prepared device can ensure the controllability and accuracy of the droplet transport path.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and in particular to a device with a controllable droplet transport path and a preparation method thereof. Background Art

[0002] Precision manipulation of droplets is a cutting-edge technology involving multiple fields such as microfluidics, surface science, materials science and control engineering. It covers the precise movement, positioning and manipulation of tiny droplets on solid surfaces, providing indispensable technical support for many key fields such as microfluidics, biomedical research and the chemical industry.

[0003] In order to achieve precise control of droplet transport, multi-point parallelism and path manipulation, researchers have developed a variety of devices with controllable droplet transport paths. These devices mainly rely on electric field, magnetic field manipulation and surface tension regulation to control the movement of droplets. However, as the application field continues to increase the complexity and precision of droplet manipulation, these devices have gradually shown the following limitations: (1) Traditional magnetic materials such as silicon steel and nickel-iron alloys are prone to lose their magnetism in high-temperature environments, which limits their application in high-temperature working environments; (2) Traditional magnetic materials such as silicon steel and nickel-iron alloys lack magnetic directivity in the initial state and are unevenly distributed. They require additional magnetization steps to obtain controllable magnetic response, but this process often leads to a decrease in magnetic field control accuracy, making it difficult to maintain stable control of the droplets during movement, thereby affecting the precise control of the transport path; (3) The preparation process of these devices usually involves multiple tedious steps such as film formation, curing, patterning and magnetization, which not only increases the complexity and cost of the preparation method, but also makes it difficult to ensure the uniformity and stability of the magnetic material, further affecting the precision of the droplet transport path.

[0004] To overcome these limitations, Chinese invention patent publication number CN115386110A proposes a flexible membrane with a controllable droplet transport path based on silicone. This membrane creates a wettability gradient by forming distinct rough and smooth areas, thereby enabling droplet manipulation. However, this membrane is primarily suitable for simple droplet movement and separation tasks; its droplet transport path accuracy is still insufficient for high-precision droplet manipulation.

[0005] In summary, the current methods for preparing devices with controllable droplet transport paths generally face problems such as complex preparation methods and limited accuracy of droplet transport paths, and are still difficult to meet actual usage needs. Summary of the Invention

[0006] The first purpose of the present invention is to propose a method for preparing a device with a controllable droplet transport path. This method not only simplifies the preparation process and improves production efficiency, but also the prepared device can accurately control the droplets and flexibly and stably transport them, ensuring the controllability and accuracy of the droplet transport path, thereby effectively overcoming the problems of complex preparation methods and insufficient accuracy of droplet transport paths in the existing technology.

[0007] The second purpose of the present invention is to propose a device with controllable droplet transport path prepared by the above-mentioned preparation method with controllable droplet transport path, which can achieve the controllability and accuracy of the droplet transport path and greatly meet the actual application needs.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] A method for preparing a device with a controllable droplet transport path comprises the following steps:

[0010] A. Partially covering the surface of a substrate with a mask; wherein the surface of the substrate includes a mask-covered area and an exposed area, the exposed area is shaped like an isosceles triangle, and multiple isosceles triangles are staggered and arranged at equal intervals, and the substrate is made of a high-temperature resistant non-magnetic material;

[0011] B. dissolving anhydrous ferric chloride in deionized water and stirring uniformly to obtain a ferric chloride solution; uniformly mixing the ferric chloride solution with a carbon-based raw material and a fluorine source raw material to obtain a ferric chloride-carbon-based-fluorine source complex;

[0012] C. evenly applying the ferric chloride-carbon-based-fluorine source complex prepared in step B to the surface of the exposed area of ​​the substrate prepared in step A to obtain a substrate having the ferric chloride-carbon-based-fluorine source complex attached to the surface;

[0013] D. processing the ferric chloride-carbon-fluorine source complex on the surface of the substrate in step C using a pulsed current to obtain a substrate having a fluorine-doped graphene-ferroferric oxide complex attached to the surface;

[0014] E. removing the mask on the surface of the substrate in step D and cleaning it to obtain a substrate having a magnetron layer; wherein the magnetron layer is a fluorine-doped graphene-ferroferric oxide combination;

[0015] F. Immerse the substrate with the magnetron layer in step E in silicone oil, take it out and hang it to stand, then deposit a lubricating layer on the surface of the substrate with the magnetron layer to obtain a device with controllable droplet transport path.

[0016] Furthermore, in step A, the vertex angle of the isosceles triangle is 20-45°.

[0017] Furthermore, in step B, the mixing ratio of the anhydrous ferric chloride and the deionized water is (0.9-1.1):2 calculated by mass ratio.

[0018] Furthermore, in step B, the mixing ratio of the ferric chloride solution, the carbon-based raw material and the fluorine source raw material is (0.45-0.55):1:(0.1-0.12) calculated by mass ratio.

[0019] Furthermore, in step D, the voltage of the pulse current is 120-140V, the current is 180-200A, and the processing time is 8-10s.

[0020] Furthermore, in step E, the thickness of the magnetron layer is 0.3 to 0.5 mm.

[0021] Furthermore, in step F, the soaking time is 4 to 6 minutes; and the hanging and standing time is 10 to 15 minutes.

[0022] Furthermore, in step A, the substrate includes any one of a glass substrate, a silicon wafer and an alumina ceramic.

[0023] Furthermore, in step B, the carbon-based raw material includes any one or more combinations of carbon black, coal powder, lignin and corn silk;

[0024] The fluorine source raw material includes any one of fluorinated graphite, perfluorooctanoic acid, perfluorohexane sulfonic acid and polytetrafluoroethylene.

[0025] A device with a controllable droplet transport path is prepared using the above-mentioned method for preparing a device with a controllable droplet transport path.

[0026] The technical solution provided by the present invention can have the following beneficial effects:

[0027] 1. The device produced by this technical solution includes a substrate, a magnetron layer, and a lubricating layer, which are arranged in sequence from bottom to top. The magnetron layer is composed of a fluorine-doped graphene-iron tetroxide combination. The iron tetroxide in the magnetron layer gives the device excellent magnetic properties. Under the action of an external magnetic field, the magnetic domains of the iron tetroxide will undergo orderly rearrangement; and the high mechanical strength of graphene ensures the stability of the device structure. Therefore, when the magnetic domains of the iron tetroxide rearrange, the surface of the magnetron layer only shows dynamic changes in the microstructure. That is, the micro-roughness and surface energy of the area close to the magnetic field on the device surface are significantly improved, while the area away from the magnetic field maintains its original smooth state and low surface energy, thus forming a dual effect of surface energy gradient and micro-roughness gradient on the device surface. When a droplet is placed in an area with high micro-roughness and high surface energy, thanks to the above-mentioned gradient effect, the droplet will spontaneously migrate to the area with low surface energy and smooth surface, realizing precise and flexible control of the droplet transmission path. At the same time, the stronger the applied magnetic field, the higher the microscopic roughness and surface energy in the area near the magnetic field. Furthermore, when the direction of droplet transport needs to be changed, this can be achieved simply by changing the direction of the applied magnetic field. Therefore, based on the above principle, droplet transport across the device surface can be achieved by applying an external magnetic field and adjusting its strength and direction.

[0028] 2. In order to further improve the controllability and accuracy of the droplet transmission path, the surface of the substrate of this technical solution includes a mask-covered area and an exposed area. The exposed area is in the shape of an isosceles triangle, and multiple isosceles triangles are staggered and arranged at equal intervals. The exposed area serves as a patterned template and can accurately replicate its shape to the magnetic control layer, so that the outer surface of the device presents a unique shape with alternating vertices and bottom edges. When the droplet is transferred to the vertices, the surface energy caused by its sharp shape increases sharply, becoming a powerful driving force for driving the droplet to gradually migrate to the adjacent bottom edge, making the droplet easy to guide and smoothly jump from the current vertices to the adjacent bottom edge. In addition, the unique shape of the alternating vertices and bottom edges on the outer surface of the device has a natural geometric guidance. When the droplet is driven by the surface energy gradient in the bottom edge area, the droplet is more inclined to move to the adjacent vertices. The effects of the above two aspects cooperate with each other to improve the controllability and accuracy of the droplet transmission path and meet actual usage needs.

[0029] 3. If the substrate material is magnetic, it will interfere with the external magnetic field, affecting the manipulation of the droplets and, consequently, the precision and controllability of the droplet transport path. Furthermore, the pulsed current process generates a high-temperature environment. If the substrate material is poorly resistant to high temperatures, thermal expansion or material deformation may occur, damaging the device structure. Therefore, this technical solution limits the substrate material to non-magnetic and high-temperature resistant materials to ensure the integrity of the device structure and the precision and controllability of the droplet transport path. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic structural diagram of a device with controllable droplet transport path according to the present invention.

[0031] Figure 2 It is a path diagram of the droplets of the present invention transported on the surface of a device with a controllable droplet transport path.

[0032] Figure 3 It is a schematic diagram of a micro-knife-shaped structure in the exposed area in the prior art.

[0033] Figure 4 It is a schematic diagram of a dumbbell-shaped structure in which the exposed area is pointed and thin in the prior art.

[0034] Among them: substrate 1, magnetron layer 2, lubricating layer 3. DETAILED DESCRIPTION

[0035] This technical solution provides a method for preparing a device with a controllable droplet transport path, comprising the following steps:

[0036] A. Partially covering the surface of a substrate with a mask; wherein the surface of the substrate includes a mask-covered area and an exposed area, the exposed area is shaped like an isosceles triangle, and multiple isosceles triangles are staggered and arranged at equal intervals, and the substrate is made of a high-temperature resistant non-magnetic material;

[0037] B. dissolving anhydrous ferric chloride in deionized water and stirring uniformly to obtain a ferric chloride solution; uniformly mixing the ferric chloride solution with a carbon-based raw material and a fluorine source raw material to obtain a ferric chloride-carbon-based-fluorine source complex;

[0038] C. evenly applying the ferric chloride-carbon-based-fluorine source complex prepared in step B to the surface of the exposed area of ​​the substrate prepared in step A to obtain a substrate having the ferric chloride-carbon-based-fluorine source complex attached to the surface;

[0039] D. processing the ferric chloride-carbon-fluorine source complex on the surface of the substrate in step C using a pulsed current to obtain a substrate having a fluorine-doped graphene-ferroferric oxide complex attached to the surface;

[0040] E. removing the mask on the surface of the substrate in step D and cleaning it to obtain a substrate having a magnetron layer; wherein the magnetron layer is a fluorine-doped graphene-ferroferric oxide combination;

[0041] F. Immerse the substrate with the magnetron layer in step E in silicone oil, take it out and hang it to stand, then deposit a lubricating layer on the surface of the substrate with the magnetron layer to obtain a device with controllable droplet transport path.

[0042] In order to overcome the problems of complex preparation methods and limited accuracy of droplet transmission paths in the existing technology, this technical solution proposes a method for preparing a device with controllable droplet transport path, including six steps: A (preparing a substrate with a mask partially covered on the surface), B (preparing a ferric chloride-carbon-based-fluorine source composite), C (applying the composite), D (pulsed current processing), E (removing the mask) and F (silicone oil immersion). By designing the surface of the substrate and selecting the substrate material, the prepared device can accurately control the droplets and flexibly and stably transmit them, ensuring the controllability and accuracy of the droplet transmission path. At the same time, compared with the traditional technology involving multiple complex processes such as film formation, curing, patterning and magnetization, this solution abandons the film formation and curing steps, and only requires pulse current processing to form a magnetic control layer in one step. Thanks to the high magnetism of ferroferric oxide, no additional magnetization step is required. The simplification of the above two aspects not only reduces the preparation cost, but also enhances the controllability and flexibility of the operation, which is conducive to the industrialization and large-scale production of the product.

[0043] Specifically, the device prepared by the present invention includes a substrate, a magnetron layer and a lubricating layer (such as Figure 1 As shown), the composition of the magnetron layer is a fluorine-doped graphene-iron tetroxide combination. The iron tetroxide in the magnetron layer gives the device excellent magnetic properties. Under the action of an external magnetic field, the magnetic domains of the iron tetroxide will be orderly rearranged; and the high mechanical strength of graphene ensures the stability of the device structure. Therefore, when the magnetic domains of the iron tetroxide are rearranged, the surface of the magnetron layer only shows dynamic changes in the microstructure, that is, the micro-roughness and surface energy of the area close to the magnetic field on the surface of the device are significantly improved, while the area away from the magnetic field maintains its original smooth state and lower surface energy, thereby forming a dual effect of surface energy gradient and micro-roughness gradient on the surface of the device. When a droplet is placed in an area with high micro-roughness and large surface energy, thanks to the above-mentioned gradient effect, the droplet will spontaneously migrate to the area with low surface energy and smooth surface, realizing precise and flexible control of the droplet transmission path. At the same time, the stronger the applied magnetic field, the higher the microscopic roughness and surface energy in the area near the magnetic field. Furthermore, when the direction of droplet transport needs to be changed, this can be achieved simply by changing the direction of the applied magnetic field. Therefore, based on the above principle, droplet transport across the device surface can be achieved by applying an external magnetic field and adjusting its strength and direction.

[0044] Furthermore, although the transfer of droplets on the device surface can be achieved by applying an external magnetic field and adjusting the strength and direction of the magnetic field, the droplet transfer path (such as Figure 2In order to further improve the controllability and accuracy of the droplet transmission path, the surface of the substrate of this technical solution includes a mask-covered area and an exposed area. The exposed area is in the shape of an isosceles triangle, and multiple isosceles triangles are staggered and arranged at equal intervals (such as Figure 2 As shown, the black area is the ferric chloride-carbon-based-fluorine source composite coating area), and the exposed area serves as a patterned template, which can accurately replicate its morphology to the magnetic control layer, so that the outer surface of the device presents a unique morphology in which the top corners and bottom edges are alternately arranged. When the droplets are transferred to the top corners, the surface energy caused by their sharp morphology increases sharply, which becomes a powerful driving force for driving the droplets to gradually migrate to the adjacent bottom edges, making the droplets easy to be guided and smoothly jump from the current top corner to the adjacent bottom edge. In addition, the unique morphology of the alternating top corners and bottom edges of the outer surface of the device has a natural geometric guidance. When the droplets are driven by the surface energy gradient in the bottom edge area, the droplets tend to move to the adjacent top corner area. The effects of the above two aspects cooperate with each other to improve the controllability and accuracy of the droplet transmission path and meet actual usage needs.

[0045] It should be noted that, because the sharp morphology of a droplet increases its surface energy dramatically when it is transferred to a vertex corner, the high surface energy of the vertex corner itself can be used to transfer the droplet from the current vertex corner to the adjacent base without the need for an external magnetic field. In other words, this technical solution can also guide the transfer of a droplet from the current vertex corner to the adjacent base using the high surface energy of the vertex corner itself, while using an external magnetic field to transfer the droplet from the current base to the next adjacent vertex corner, thereby increasing the flexibility of the droplet transfer method.

[0046] Furthermore, the surface energy difference and natural guiding effect of the top corner area of ​​the device's outer surface make it easy for the droplets to be guided and transported, while the wider shape of the bottom edge area of ​​the device's outer surface provides a stable transmission path for the droplets, which is conducive to forming a directional and controllable droplet movement trajectory, thereby ensuring the continuity and smoothness of the droplet manipulation, and supporting the synchronous transmission of multiple droplets and the planning of complex paths. At the same time, the characteristics of droplets being easy to be guided and transported in the top corner area and easy to stably transport in the bottom edge area also bring higher flexibility to droplet manipulation, making the device of this technical solution suitable for a variety of liquid types and a wide range of application scenarios, such as precise liquid flow control in microfluidic systems, cell culture array preparation in the biomedical field, and precise reaction and separation processes in chemical synthesis. In addition, since this technical solution controls the movement of droplets through the dual effects of surface energy gradient and microscopic roughness gradient and the guiding effect of the top corner area, compared with the existing technology that constructs obvious rough areas and smooth areas, this technical solution has higher control accuracy and more stable transmission of droplets.

[0047] More specifically, ferric chloride itself is a solid. When it is directly mixed with a carbon-based raw material and a fluorine-source carbon-based raw material, uneven mixing is easily caused. Therefore, the present technical solution first prepares a ferric chloride solution before the coating step, and evenly mixes the ferric chloride solution with the carbon-based raw material and the fluorine-source raw material to obtain a ferric chloride-carbon-based-fluorine-source complex. The ferric chloride-carbon-based-fluorine-source complex is then evenly coated on the surface of the exposed area of ​​the substrate in step A to obtain a substrate with the ferric chloride-carbon-based-fluorine-source complex attached to the surface. This facilitates the processing of the ferric chloride-carbon-based-fluorine-source complex on the surface of the substrate using a pulse current, thereby further simplifying the preparation method.

[0048] Secondly, the ferric chloride-carbon-based-fluorine source complex on the surface of the substrate in step C is processed by pulse current. The instantaneous high temperature generated by the pulse current causes the ferric chloride solution to instantly change from liquid phase to gas phase and diffuse, and the gas phase ferric chloride undergoes an oxidation-reduction reaction in this process to generate gas phase ferroferric oxide. When the gas phase ferroferric oxide contacts the surface of the substrate with a lower temperature, it will condense and deposit on the surface of the substrate to form ferroferric oxide particles, and due to the uniformity of diffusion, the deposited ferroferric oxide particles are evenly distributed on the surface of the substrate; at the same time, the instantaneous high temperature generated by the pulse current can also process carbon-based raw materials, because the elements contained in carbon-based raw materials are mainly carbon, nitrogen and oxygen, and The temperature of pulse current processing is relatively high. During the pulse current processing, the bonds between atoms or molecules of carbon-based raw materials are interrupted and converted into carbon dioxide, carbon monoxide, nitrogen dioxide, nitric oxide and graphene. Among them, carbon dioxide, carbon monoxide, nitrogen dioxide and nitric oxide enter the air in the form of gas, and only graphene remains in the final processed product. In this process, the fluorine source can be further incorporated into the graphene through diffusion and infiltration to form fluorine-doped graphene, and the fluorine-doped graphene is then tightly combined with the ferroferric oxide particles to form a fluorine-doped graphene-ferroferric oxide complex.

[0049] It should be noted that in conventional technology, the exposed area on the substrate surface is generally designed to be in the shape of a micro-knife (e.g. Figure 3 The black area in the middle) or the dumbbell shape with a thin tip (as shown Figure 4(As shown in the black area in the middle), the above design uses the template effect to make the device surface also present corresponding shape characteristics. However, the above-mentioned sharp dumbbell-shaped or micro-knife-shaped shape needs to rely on external force to swing or rotate, and its surface morphology is changed by adjusting the contact angle and contact area with the droplet to achieve the guidance of the droplet. However, the above-mentioned dynamic motion mode is completely dependent on external drive, so it is easy to cause mechanical fatigue problems, which in turn affects the accuracy of manipulation. In this technical solution, the exposed area on the surface of the substrate adopts staggered isosceles triangles, so that the magnetic control layer presents a static geometric pattern. It can effectively guide the transmission and movement of droplets by relying solely on the sharp increase in surface energy caused by the sharp shape of the vertex angle, avoiding the problem of reduced droplet manipulation accuracy caused by the exposed area on the substrate surface being a sharp dumbbell-shaped or micro-knife-shaped, thereby ensuring the accuracy of the droplet transmission path.

[0050] Furthermore, the mask on the substrate surface is removed and cleaned. After the mask is removed, a magnetron layer with the desired pattern is formed, which facilitates subsequent processing or treatment of the magnetron layer. Furthermore, the cleaning step facilitates a good bond between the magnetron layer and the substrate, thereby improving the adhesion and stability of the magnetron layer, thereby enhancing the operating efficiency, stability, and service life of the device. It should be noted that in step D, the cleaning step specifically involves cleaning with deionized water.

[0051] Again, although the fluorine-doped graphene in the magnetron layer can reduce the surface energy, the hydrophobicity of the fluorine-doped graphene in the magnetron layer alone is not enough to completely eliminate the friction between the droplets and the device surface during droplet manipulation, and it is impossible to ensure that the droplets move smoothly and stably on the device surface. Therefore, in this technical solution, the substrate with the magnetron layer in step E is immersed in silicone oil, taken out and suspended to stand, so that a lubricating layer is deposited on the surface of the substrate with the magnetron layer. The lubricating layer can further reduce the friction between the droplets and the device surface, so that the droplets can move controllably along the transmission path on the device surface under the dual effect of the surface energy gradient or the surface energy gradient and the micro-roughness gradient, thereby improving the smoothness and precision of droplet manipulation. In addition, the suspension and stillness can allow excess silicone oil to flow out from the surface of the lubricating layer, ensuring the uniformity of the lubricating layer.

[0052] Finally, if the substrate material is magnetic, it will interfere with the external magnetic field, affecting the manipulation of the droplets and, consequently, the precision and controllability of the droplet transport path. Furthermore, the pulsed current process generates a high-temperature environment. If the substrate material is poorly resistant to high temperatures, thermal expansion or material deformation may occur, damaging the device structure. Therefore, this technical solution limits the substrate material to non-magnetic and high-temperature resistant materials to ensure the integrity of the device structure and the precision and controllability of the droplet transport path.

[0053] It should be noted that the spacing between adjacent isosceles triangles in the exposed area of ​​the substrate surface of this technical solution can be designed according to the diameter and surface tension of the droplets actually required to be transported. Generally, the spacing between adjacent isosceles triangles is ≤ 1 / 2 of the droplet diameter, which will not be described in detail here.

[0054] Preferably, the silicone oil includes any one of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, ethyl hydrogen silicone oil, methylphenyl silicone oil, methylchlorophenyl silicone oil, methylethoxy silicone oil, methyltrifluoropropyl silicone oil and methylvinyl silicone oil.

[0055] To further illustrate, in step A, the vertex angle of the isosceles triangle is 20-45°.

[0056] If the vertex angle of an isosceles triangle is too small or too sharp, droplets may become trapped in the vertex area, making it difficult for them to move smoothly to the adjacent base, thus hindering their transmission process. If the vertex angle of an isosceles triangle is too large, the guiding effect of the droplet at the vertex is weakened, the increase in surface energy is limited, and the controllability of the droplet decreases, making it prone to irregular diffusion along the surface of the isosceles triangle. Therefore, this technical solution optimizes the angle of the vertex angle of the isosceles triangle to ensure the controllability and precision of the droplet transmission path.

[0057] Further, in step B, the mixing ratio of the anhydrous ferric chloride and the deionized water is (0.9-1.1):2 calculated by mass ratio.

[0058] If the ratio of anhydrous ferric chloride to deionized water is too small, that is, the content of anhydrous ferric chloride is too little, the device's response to the magnetic field will be weakened, affecting its accuracy in controlling the droplets; if the ratio of anhydrous ferric chloride to deionized water is too large, that is, the content of anhydrous ferric chloride is too high, although the device will be more sensitive to the magnetic field, it will cause the overall structure of the device to become brittle, the device's reversible deformation ability will be reduced, and it will be more prone to structural damage.

[0059] Further, in step B, calculated by mass ratio, the mixing ratio of the ferric chloride solution, the carbon-based raw material and the fluorine source raw material is (0.45-0.55):1:(0.1-0.12).

[0060] If the proportion of ferric chloride solution is too large, the ferric chloride-carbon-based-fluorine source complex will be too dilute, the fluidity will increase, and it will not be able to be well fixed on the substrate surface for patterning processing; if the proportion of ferric chloride solution is too small, the ferric chloride-carbon-based-fluorine source complex will be too dry, and it will not be easy to evenly apply and disperse on the substrate surface, resulting in poor thickness uniformity of the obtained device, affecting the accuracy of its control of the droplets.

[0061] Furthermore, within a certain range, the conductivity of the carbon-based raw material increases with the increase of its density. However, when the density of the carbon-based raw material increases to a certain extent, due to the close packing between the particles, the electron transmission path may be blocked, which reduces the conductivity. In this technical solution, the area where the substrate can be coated with the ferric chloride-carbon-based-fluorine source composite is fixed. If there is too much carbon-based raw material, the density of the carbon-based raw material in this area will increase, resulting in the overall resistance of the ferric chloride-carbon-based-fluorine source composite being too large, affecting the conversion rate of the carbon-based raw material into graphene, thereby reducing the performance of the device.

[0062] Furthermore, if the proportion of fluorine source raw materials is too large, it will affect the uniformity of the distribution of the fluorine source raw materials on the graphene surface, causing an imbalance in the surface energy gradient of the device and reducing the accuracy of droplet manipulation; if the proportion of fluorine source raw materials is too small, the hydrophobicity of the device surface will be reduced, affecting the rolling and manipulation performance of the droplets, making it difficult for the droplets to move quickly, and causing the droplets to be locally retained on the device surface.

[0063] Further description, in step D, the voltage of the pulse current is 120-140V, the current is 180-200A, and the processing time is 8-10s.

[0064] By limiting the processing parameters of the pulse current, it is beneficial to convert the ferric chloride-carbon-fluorine source complex into a fluorine-doped graphene-ferroferric oxide combination in one step, improving the quality of the device and further simplifying the preparation method.

[0065] Further, in step E, the thickness of the magnetron layer is 0.3 to 0.5 mm.

[0066] The magnetron layer is obtained by pulse processing of fluorine-doped graphene-iron tetroxide. If the thickness of the magnetron layer exceeds the appropriate range, the thickness of the fluorine-doped graphene-iron tetroxide will also be thicker. The thicker fluorine-doped graphene-iron tetroxide will hinder the effective transfer of heat, making it difficult for the interior of the fluorine-doped graphene-iron tetroxide to quickly reach the required processing temperature, thereby affecting the uniformity and stability of the magnetron layer.

[0067] Further description, in step F, the soaking time is 4 to 6 minutes; the hanging and standing time is 10 to 15 minutes.

[0068] If the immersion time is too short, the silicone oil will not easily evenly cover the surface of the device, resulting in insufficient lubricity in some areas of the device; if the immersion time is too long, the silicone oil will excessively penetrate into the magnetron layer, resulting in a decrease in the cohesive force between the raw materials in the magnetron layer, thereby increasing the adhesion between the magnetron layer and the droplets, which is not conducive to the precise control of the droplets.

[0069] If the suspension time is too short, too much silicone oil may remain on the surface of the device, resulting in poor thickness uniformity of the device and reduced controllability of the device over the droplets. If the suspension time is too long, it can easily lead to a decrease in production efficiency.

[0070] Further description: In step A, the substrate includes any one of a glass substrate, a silicon wafer and an alumina ceramic.

[0071] Glass substrates, silicon wafers, and alumina ceramics are all non-magnetic and have good high temperature resistance. Therefore, in this technical solution, the substrate is preferably any one of a glass substrate, a silicon wafer, and alumina ceramics, which is conducive to ensuring the performance of the product.

[0072] Further, in step B, the carbon-based raw material includes any one or more combinations of carbon black, coal powder, lignin and corn silk;

[0073] The fluorine source raw material includes any one of fluorinated graphite, perfluorooctanoic acid, perfluorohexane sulfonic acid and polytetrafluoroethylene.

[0074] Carbon black, coal powder, lignin and corn silk can all be converted into graphene under pulsed current processing conditions, which helps to ensure the performance of the product.

[0075] Furthermore, when the fluorine source reacts with the magnetic material ferroferric oxide, some of the fluorine atoms are unable to incorporate into the graphene, significantly reducing the device's hydrophobicity and affecting the accuracy of droplet transport. This also leads to a decrease in the device's magnetism, similarly affecting droplet transport accuracy. Therefore, this technical solution utilizes raw materials such as fluorinated graphite, perfluorooctanoic acid, perfluorohexane sulfonic acid, and polytetrafluoroethylene, which do not react with the magnetic material ferroferric oxide at high temperatures, to ensure accurate droplet transport.

[0076] A device with a controllable droplet transport path is prepared using the above-mentioned method for preparing a device with a controllable droplet transport path.

[0077] This technical solution also proposes a device with controllable droplet transport path prepared using a preparation method with controllable precision of droplet transport path. The device can precisely control droplets and flexibly and stably transport them, thereby achieving controllability and precision of the droplet transport path, greatly meeting practical application needs.

[0078] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0079] Example 1

[0080] A. Partially covering the surface of a glass substrate with a mask; wherein the surface of the glass substrate includes a mask-covered area and an exposed area, the exposed area being in the shape of an isosceles triangle with a vertex angle of 20°, and multiple isosceles triangles being staggered and evenly spaced;

[0081] B. Dissolve anhydrous ferric chloride in deionized water and stir to obtain a ferric chloride solution; mix the ferric chloride solution with carbon black and perfluorooctanoic acid to obtain a ferric chloride-carbon black-perfluorooctanoic acid complex; the mass ratio of anhydrous ferric chloride to deionized water is 1:2; the mass ratio of ferric chloride solution, carbon black, and perfluorooctanoic acid is 0.5:1:0.1;

[0082] C. evenly applying the ferric chloride-carbon black-perfluorooctanoic acid complex prepared in step B to the surface of the exposed area of ​​the glass substrate prepared in step A to obtain a glass substrate having the ferric chloride-carbon-based-fluorine source complex attached to the surface;

[0083] D. Processing the ferric chloride-carbon-based-fluorine source complex on the surface of the glass substrate in step C for 8 seconds using a pulse current of 120 V and 180 A to obtain a glass substrate with a fluorine-doped graphene-ferroferric oxide complex attached to the surface;

[0084] E. removing the mask on the surface of the glass substrate in step D and cleaning it to obtain a glass substrate having a magnetron layer; wherein the magnetron layer has a thickness of 0.3 mm and is a fluorine-doped graphene-ferroferric oxide combination;

[0085] F. Soak the glass substrate with the magnetron layer in step E in methyl silicone oil for 4 minutes, remove it and hang it for 15 minutes, then deposit a lubricating layer on the surface of the glass substrate with the magnetron layer to obtain a device with controllable droplet transport path.

[0086] The device with a controllable droplet transport path obtained in Example 1 is placed in a magnetic field, and droplets are placed at the top corner or bottom edge of the outer surface of the device with a controllable droplet transport path. During the droplet transport process, the magnetic field strength and direction are adjusted to manipulate the droplets to be transported along a preset path, and the deviation of the droplet transport path is observed using a microscope.

[0087] The results show that the device with controllable droplet transport path obtained in Example 1 can control the droplet transport path to be transmitted according to the preset path, and the droplets have basically no deviation during the transmission process, and the controllability and accuracy of the droplet transmission path are high.

[0088] Example 2

[0089] A. Partially covering the surface of the silicon wafer with a mask; wherein the surface of the glass substrate includes a mask-covered area and an exposed area, the exposed area being shaped like an isosceles triangle with a vertex angle of 30°, and multiple isosceles triangles being staggered and evenly spaced;

[0090] B. Dissolve anhydrous ferric chloride in deionized water and stir to obtain a ferric chloride solution; then mix the ferric chloride solution with pulverized coal and perfluorohexane sulfonic acid to obtain a ferric chloride-coal-perfluorohexane sulfonic acid complex; the mass ratio of anhydrous ferric chloride to deionized water is 0.9:2; the mass ratio of ferric chloride solution, pulverized coal, and perfluorohexane sulfonic acid is 0.45:1:0.12;

[0091] C. evenly applying the ferric chloride-coal powder-perfluorohexane sulfonic acid complex prepared in step B to the surface of the exposed area of ​​the silicon wafer prepared in step A to obtain a silicon wafer having the ferric chloride-carbon-based-fluorine source complex attached to the surface;

[0092] D. Processing the ferric chloride-carbon-based-fluorine source complex on the surface of the silicon wafer in step C for 10 seconds using a pulse current of 130 V and 200 A to obtain a silicon wafer with a fluorine-doped graphene-ferroferric oxide complex attached to the surface;

[0093] E. removing the mask on the surface of the silicon wafer in step D and cleaning it to obtain a silicon wafer with a magnetron layer; wherein the magnetron layer has a thickness of 0.5 mm and is a fluorine-doped graphene-ferroferric oxide combination;

[0094] F. Soak the silicon wafer with the magnetron layer in step E in phenyl silicone oil for 6 minutes, take it out and hang it to stand for 15 minutes, and then deposit it on the surface of the silicon wafer with the magnetron layer to obtain a device with controllable droplet transport path.

[0095] The device with a controllable droplet transport path obtained in Example 2 was placed in a magnetic field, and droplets were placed at the top corner or bottom edge of the outer surface of the device with a controllable droplet transport path. During the droplet transport process, the magnetic field strength and direction were adjusted to manipulate the droplets to be transported along a preset path, and the deviation of the droplet transport path was observed using a microscope.

[0096] The results show that the device with controllable droplet transport path obtained in Example 2 can control the droplet transport path to be transmitted according to the preset path, and the droplets have basically no deviation during the transmission process, and the controllability and accuracy of the droplet transmission path are high.

[0097] Example 3

[0098] A. Partially covering the surface of the alumina ceramic with a mask; wherein the surface of the glass substrate includes a mask-covered area and an exposed area, the exposed area being in the shape of an isosceles triangle with a vertex angle of 45°, and multiple isosceles triangles being staggered and arranged at equal intervals;

[0099] B. Dissolve anhydrous ferric chloride in deionized water and stir to obtain a ferric chloride solution; mix the ferric chloride solution with lignin and polytetrafluoroethylene to obtain a ferric chloride-lignin-polytetrafluoroethylene composite; the mass ratio of anhydrous ferric chloride to deionized water is 1.1:2; the mass ratio of the ferric chloride solution, carbon black, and perfluorooctanoic acid is 0.55:1:0.1;

[0100] C. evenly applying the ferric chloride-lignin-polytetrafluoroethylene complex prepared in step B to the surface of the exposed area of ​​the alumina ceramic prepared in step A to obtain an alumina ceramic with the ferric chloride-lignin-polytetrafluoroethylene complex attached to the surface;

[0101] D. Processing the ferric chloride-carbon-based-fluorine source complex on the surface of the alumina ceramic in step C for 9 seconds using a pulse current of 140 V and 190 A to obtain an alumina ceramic with a fluorine-doped graphene-ferroferric oxide complex attached to the surface;

[0102] E. removing the mask on the surface of the alumina ceramic in step D and cleaning it to obtain an alumina ceramic having a magnetron layer; wherein the magnetron layer has a thickness of 0.4 mm and is a fluorine-doped graphene-ferroferric oxide combination;

[0103] F. Soak the alumina ceramic with the magnetron layer in step E in ethyl silicone oil for 5 minutes, remove it and hang it to stand for 12 minutes, and then deposit a lubricating layer on the surface of the alumina ceramic with the magnetron layer to obtain a device with controllable droplet transport path.

[0104] The device with a controllable droplet transport path obtained in Example 3 was placed in a magnetic field, and droplets were placed at the top corner or bottom edge of the outer surface of the device with a controllable droplet transport path. During the droplet transport process, the magnetic field strength and direction were adjusted to manipulate the droplets to be transported along a preset path, and the deviation of the droplet transport path was observed using a microscope.

[0105] The results show that the device with controllable droplet transport path obtained in Example 3 can control the droplet transport path to be transmitted according to the preset path, and the droplets have basically no deviation during the transmission process, and the controllability and accuracy of the droplet transmission path are high.

[0106] Comparative Example 1

[0107] Except that in step A, the substrate is a substrate without a mask, the remaining steps are the same as those in Example 1.

[0108] The device with a controllable droplet transport path obtained in Comparative Example 1 was placed in a magnetic field, and droplets were placed at any position of the device with a controllable droplet transport path. During the droplet transmission process, the magnetic field strength was adjusted to manipulate the droplets to be transmitted along a preset path, and the droplet transmission path and stability were observed using a microscope.

[0109] The results show that although the device with controllable droplet transport path obtained in Example 1 can control the droplet transport path to transport the droplet along the preset path, the controllability and accuracy of the droplet transport path are poor.

[0110] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and are not to be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will readily conceive of other specific embodiments of the present invention without inventive effort, and such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a device with a controllable droplet transport path, characterized in that: The following steps are involved: A. Partially covering the surface of a substrate with a mask; wherein the surface of the substrate includes a mask-covered area and an exposed area, the exposed area is shaped like an isosceles triangle, the vertex angle of the isosceles triangle is 20 to 45 degrees, and multiple isosceles triangles are staggered and evenly spaced, and the substrate is made of a high-temperature resistant non-magnetic material; B. dissolving anhydrous ferric chloride in deionized water and stirring uniformly to obtain a ferric chloride solution; uniformly mixing the ferric chloride solution with a carbon-based raw material and a fluorine source raw material to obtain a ferric chloride-carbon-based-fluorine source composite; wherein, calculated by mass ratio, the mixing ratio of the anhydrous ferric chloride to the deionized water is (0.9-1.1):2; calculated by mass ratio, the mixing ratio of the ferric chloride solution, the carbon-based raw material and the fluorine source raw material is (0.45-0.55):1:(0.1-0.12); the fluorine source raw material comprises any one of fluorinated graphite, perfluorooctanoic acid, perfluorohexane sulfonic acid and polytetrafluoroethylene; C. evenly applying the ferric chloride-carbon-based-fluorine source complex prepared in step B to the surface of the exposed area of ​​the substrate prepared in step A to obtain a substrate having the ferric chloride-carbon-based-fluorine source complex attached to the surface; D. processing the ferric chloride-carbon-based-fluorine source complex on the surface of the substrate in step C using a pulsed current to obtain a substrate having a fluorine-doped graphene-ferroferric oxide complex attached to the surface; E. removing the mask on the surface of the substrate in step D and cleaning it to obtain a substrate having a magnetron layer; wherein the magnetron layer is a fluorine-doped graphene-ferroferric oxide combination; F. Immerse the substrate with the magnetron layer in step E in silicone oil, take it out and hang it to stand, then deposit a lubricating layer on the surface of the substrate with the magnetron layer to obtain a device with controllable droplet transport path.

2. The method for preparing a device with controllable droplet transport path according to claim 1, characterized in that: In step D, the voltage of the pulse current is 120-140V, the current is 180-200A, and the processing time is 8-10s.

3. The method for preparing a device with controllable droplet transport path according to claim 1, characterized in that: In step E, the thickness of the magnetron layer is 0.3-0.5 mm.

4. The method for preparing a device with controllable droplet transport path according to claim 1, characterized in that: In step F, the soaking time is 4 to 6 minutes; the hanging and standing time is 10 to 15 minutes.

5. The method for preparing a device with controllable droplet transport path according to claim 1, characterized in that: In step A, the substrate includes any one of a glass substrate, a silicon wafer and an alumina ceramic.

6. The method for preparing a device with controllable droplet transport path according to claim 1, characterized in that: In step B, the carbon-based raw material includes any one or more combinations of carbon black, coal powder, lignin and corn silk.

7. A device with a controllable droplet transport path, characterized in that: The device is prepared using the method for preparing a device with a controllable droplet transport path according to any one of claims 1 to 6.

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