Magnetic responsive suspended droplet manipulation platform and preparation method thereof

Abstract

The application relates to the technical field of micro-nano processing, and particularly relates to a magnetic response suspended droplet control platform, which comprises a silica gel substrate, silica gel microcolumns arranged in an array on the silica gel substrate and a silica gel film installed at the top end of the silica gel microcolumns, and the silica gel substrate and the silica gel microcolumns are integrally formed. In the magnetic response suspended droplet control platform, the silica gel film has large concave deformation and high sensitivity, can freely control droplets, and solves the problem that the current magnetic control film needs to be placed in suspension and has small concave deformation, and meanwhile, the magnetic response suspended droplet control platform can complete horizontal transportation and anti-gravity transportation of droplets.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-nano processing technology, and particularly relates to a magnetic response suspension type droplet manipulation platform and a preparation method of the magnetic response suspension type droplet manipulation platform. BACKGROUND

[0002] Droplet manipulation is widely used in the fields of biomedicine, microfluidic systems, chemical analysis and synthesis, etc. Precise manipulation of droplets can avoid waste of reagents and save costs, thereby attracting widespread attention. Generally, the mechanism of droplet movement can be divided into two types, one is the interfacial energy gradient at the solid / liquid surface (wettability or structure gradient), and the other is the interfacial energy gradient at the free interface (Marangoni stress). Based on the above mechanism, various external stimulation strategies, such as magnetic, optical, acoustic, thermal and other types of induced gradient, are used to convert into droplet movement, and then intelligent manipulation of droplets is realized. Compared with other stimulation methods, magnetic response is a kind of penetrating, non-power and non-contact control method, which can be managed in space and time by accurately changing the field strength and direction without any predefined surface pattern, and has the advantages of simple operation and low cost.

[0003] Driving droplets by using magnetic response film is a convenient driving strategy, which has good development and application prospect. The magnetic response film is usually composed of a magnetic driving layer and a deformable substrate. Under the action of a magnetic field, the film is concave, and the droplet is transported by its own gravity. However, in order to deform the film, the magnetic response film needs to be placed in suspension, and because the driving force is the gravity of the droplet, the droplet can only be transported in the horizontal plane, and it is difficult to transport against gravity. In addition, the current magnetic response film also has the disadvantages of small concave deformation and low film sensitivity, which limits the application of the magnetic response film in droplet transportation. Therefore, it is a challenge to prepare a film with good performance and large concave deformation. SUMMARY

[0004] The present application provides a magnetic response suspension type droplet manipulation platform and a preparation method thereof to overcome the deficiencies of the prior art.

[0005] The present application solves the above technical problems by the following technical means:

[0006] A magnetic response suspension type droplet manipulation platform comprises a silica gel substrate, silica gel microcolumns arranged in an array on the silica gel substrate, and a silica gel film mounted at the top end of the silica gel microcolumns, wherein the silica gel substrate and the silica gel microcolumns are integrally formed.

[0007] As an improvement of the above technical solution, the diameter of the top end of the silica gel microcolumns ranges from 100 um to 180 um.

[0008] A method for fabricating a magnetically responsive suspended droplet manipulation platform includes the following steps:

[0009] S1. Fabrication of micro-via array template: Micro-vias distributed in an array are drilled on the template using a femtosecond laser.

[0010] S2. Fabrication of micropillar array structure:

[0011] S2.1 Preparation of mixed solution: The silica gel solution, magnetic particles and silicone oil are thoroughly mixed and stirred at a mass ratio of 1:1:0.1 to obtain a mixed solution;

[0012] S2.2. Apply the mixed solution evenly to the upper surface of the micro-hole array template, and evacuate until the mixed solution completely enters the interior of each micro-hole;

[0013] S2.3. Use a magnet to vertically magnetize the micro-via array template, place the magnetized micro-via array template on a glass plate, and after natural curing for 6 hours, peel the silicone cured by the mixed solution off the micro-via array template to obtain a micropillar array structure. The part of the micropillar array structure located on the surface of the micro-via array template is a silicone substrate, and the part located in the micro-vias of the micro-via array template is a silicone micropillar.

[0014] S2.4 uses a femtosecond laser to perform direct writing operations on a micropillar array structure;

[0015] S3. Silicone film preparation: After thoroughly mixing silicone solution and silicone oil at a mass ratio of 1:0.1, pour the mixture onto the surface of a glass slide with adhesive tape, and spin-coat the mixture to obtain a silicone film.

[0016] S4. Fabrication of a magnetically responsive suspended droplet manipulation platform: A micropillar array structure is mounted together with a silicone film, wherein the top of the silicone micropillar is in contact with the silicone film. After curing in a natural environment for 3 hours, it is peeled off from the surface of a glass slide to obtain a magnetically responsive suspended droplet manipulation platform.

[0017] S5. Perform femtosecond laser direct writing on the silicone film in the magnetic response suspended droplet manipulation platform, and then apply oil to the surface of the silicone film.

[0018] As an improvement to the above technical solution, in steps S2.1 and S3, the silicone solution is a solution in which silicone prepolymer and curing agent are mixed in a mass ratio of 1:1.

[0019] As an improvement to the above technical solution, in steps S2.4 and S5, the scanning parameters for the femtosecond laser direct writing operation are: number of scans: 1-3 times, laser power: 100-450mw, and scanning speed: 2-30mm / s.

[0020] As an improvement to the above technical solution, the material of the template in step S1 is either PTFE or PDMS.

[0021] As an improvement to the above technical solution, in step S3, the parameters for spin coating are: rotation speed: 100-1000 rpm, duration: 1-3 min.

[0022] As an improvement to the above technical solution, in step S1, the thickness of the template is 1mm.

[0023] The beneficial effects of this invention are:

[0024] In the magnetically responsive suspended droplet manipulation platform of this invention, the silicone film has large concave deformation and high sensitivity, enabling more free manipulation of droplets. This solves the problem that current magnetically controlled films need to be suspended and have small concave deformation. At the same time, the magnetically responsive suspended droplet manipulation platform of this invention can complete both horizontal and anti-gravity transport of droplets.

[0025] The magnetically responsive suspended droplet manipulation platform manufactured by the present invention has a large silicone film concave deformation and high sensitivity, which enables more free manipulation of droplets. It solves the problem that current magnetically controlled films need to be suspended and have small concave deformation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the magnetically responsive suspended droplet manipulation platform structure of Embodiment 1 of the present invention;

[0027] Figure 2 This is a comparison diagram of the film bending performance of silicone micropillars with different top diameters in Embodiment 1 of the present invention;

[0028] Figure 3 This is a schematic diagram demonstrating the droplet manipulation achieved by the magnetically responsive suspended droplet manipulation platform in Embodiment 1 of the present invention.

[0029] Figure 4 This is a schematic diagram of the magnetically responsive suspended droplet manipulation platform used in Embodiment 1 of the present invention to achieve anti-gravity transport of droplets.

[0030] Figure reference numerals: 1. Silicone substrate; 2. Silicone micropillar; 3. Silicone film. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0033] Example 1

[0034] like Figure 1 As shown, this embodiment of a magnetically responsive suspended droplet manipulation platform includes a silicone substrate 1, silicone micropillars 2 arranged in an array on the silicone substrate 1, and a silicone film 3 installed on the top of the silicone micropillars 2. The silicone substrate 1 and the silicone micropillars 2 are integrally formed.

[0035] The diameter of the tip of the silicone micropillar 2 ranges from 100 μm to 180 μm. In this embodiment, the diameter of the tip of the silicone micropillar 2 is set to 100 μm. In other embodiments, the diameter of the tip of the silicone micropillar 2 can also be set to 120 μm, 140 μm, or 180 μm. (See reference...) Figure 2 , Figure 2 The figures, from top to bottom, represent the bending performance of the silicone micropillars 2 when the diameter of their tips is 100 μm, 20 μm, 140 μm, and 180 μm. As can be seen from the figures, the silicone micropillars 2 exhibit the best bending ability when the tip diameter is 100 μm; they bend uniformly in one direction, resulting in a large indentation in the silicone film 3. While the bending deformation of the silicone micropillars 2 decreases as the tip diameter increases, even when the tip diameter reaches 180 μm, the silicone micropillars 2 can still be folded, causing the silicone film 3 to form a pit.

[0036] In this embodiment, a magnetically responsive suspended droplet manipulation platform with a top diameter of 100 μm is used to manipulate the droplets. The method for droplet manipulation using the magnetically responsive suspended droplet manipulation platform of this invention includes the following steps, as described above. Figure 3 The values ​​represent the changes in droplet position from 0 to 4 seconds. The left side shows the droplet moving from the right side of the platform to the left side, and the right side shows the droplet moving from the left side of the platform to the right side.

[0037] 1. A droplet is placed on the surface of the platform; 2. Using two 1.5×1.5cm N52 magnets, the droplet is moved from the right side of the platform to the left side at a constant speed, and then from the left side of the platform to the right side at a constant speed. The droplet can be clearly seen making a back-and-forth motion.

[0038] The magnetically responsive suspended droplet manipulation platform in this embodiment can also transport droplets against gravity, including the following steps, as described in the reference. Figure 4 , represents the change in droplet position during 0-4s;

[0039] 1. Tilt the platform; 2. Drop a drop onto the surface of the platform; 3. Use two 1.5×1.5cm N52 magnets to move the drop from the bottom of the platform to the top at a constant speed. You can see that the drop moves against gravity as the silicone film 3 is indented.

[0040] In the magnetically responsive suspended droplet manipulation platform of this invention, the silicone film 3 has a large concave deformation and high sensitivity, enabling more free manipulation of droplets. This solves the problem that current magnetically controlled films need to be suspended and have small concave deformation. At the same time, the magnetically responsive suspended droplet manipulation platform of this invention can complete both horizontal and anti-gravity transport of droplets.

[0041] A method for fabricating a magnetically responsive suspended droplet manipulation platform includes the following steps:

[0042] S1. Fabrication of micro-hole array template: Micro-holes distributed in an array are drilled on the template using a femtosecond laser. The laser power and scanning speed during the processing are set to 600mW and 10mm / s, respectively. In other embodiments, a marking machine can also be used to process the micro-holes. The preferred material of the template is PTFE, but PDMS can also be used in other embodiments.

[0043] S2. Fabrication of micropillar array structure:

[0044] S2.1 Preparation of Mixed Solution: Mix the silicone solution, magnetic particles and silicone oil in a mass ratio of 1:1:0.1 for 5 minutes to obtain a mixed solution. The addition of silicone oil extends the curing time of the silicone solution to ensure that it can be thoroughly mixed to obtain a uniformly mixed solution. The silicone solution is a solution in which silicone prepolymer and curing agent are mixed in a mass ratio of 1:1.

[0045] S2.2. Apply the mixed solution evenly to the upper surface of the micro-hole array template, and remove the gas inside the micro-hole by vacuuming until the mixed solution completely enters the interior of each micro-hole. The vacuuming time is set to 1 minute and 30 seconds.

[0046] S2.3. Use a magnet to vertically magnetize the micro-via array template. Set the magnetization time to 15 seconds. Place the magnetized micro-via array template on a glass plate and allow it to cure naturally for 6 hours. Then, peel the silicone cured by the mixed solution off the micro-via array template to obtain a micropillar array structure. The part of the micropillar array structure located on the surface of the micro-via array template is the silicone substrate 1, and the part located in the micro-vias of the micro-via array template is the silicone micropillar 2.

[0047] S2.4 uses a femtosecond laser to perform direct writing operations on a micropillar array structure;

[0048] S3. Silicone Film Fabrication: A silicone solution and silicone oil are thoroughly mixed at a mass ratio of 1:0.1. The silicone solution is a mixture of silicone prepolymer and curing agent at a mass ratio of 1:1. This mixture is poured onto a glass slide with adhesive tape, and then spin-coated to obtain a silicone film 3. The spin-coating parameters are: rotation speed: 100–1000 rpm, time: 1–3 min. In this embodiment, the spin-coating parameters are set to a rotation speed of 800 rpm and a time of 1 minute.

[0049] S4. Fabrication of a magnetically responsive suspended droplet manipulation platform: The micropillar array structure is mounted together with the silicone film 3, wherein the top of the silicone micropillar 2 is in contact with the silicone film 3. After curing in the natural environment for 3 hours, it is peeled off from the surface of the glass slide to obtain the magnetically responsive suspended droplet manipulation platform.

[0050] S5. Perform femtosecond laser direct writing on the silicone film 3 in the magnetic response suspended droplet manipulation platform, and then apply oil to the surface of the silicone film 3. In this embodiment, the oil is DuPont perfluoropolyether lubricating oil.

[0051] In steps S2.4 and S5, the scanning parameters for the femtosecond laser direct writing operation are: number of scans: 1-3 times, laser power: 100-450mw, scanning speed: 2-30mm / s. In this embodiment, the steps of the femtosecond laser direct writing operation are as follows: first, unidirectional direct writing is performed with a laser power of 300mW, a scanning speed of 20mm / s, 1 scan, and a fill interval of 0.02mm; then, cross-direct writing is performed with a laser power of 300mW, a scanning speed of 10mm / s, 1 scan, and a fill interval of 0.08mm.

[0052] In step S1 of this embodiment, the thickness of the template is 1 mm, meaning the height of the micro-holes processed on the template and the height of the silicone micropillars 2 are both 1 mm. However, in other embodiments, as long as the silicone film 3 can be indented under the action of a magnet and can drive the droplet to continue moving, the thickness of the template, the height of the micro-holes on the template, and the height of the silicone micropillars 2 can also be other heights, such as 2 mm.

[0053] This invention uses femtosecond laser processing technology to process micro-holes, which has the advantages of high processing precision, small thermal response area, no damage to the material itself, and very clear micro-nano structures.

[0054] The magnetically responsive suspended droplet manipulation platform manufactured by the present invention has a large concave deformation of the silicone film 3, high sensitivity, and can manipulate droplets more freely, solving the problem that current magnetically controlled films need to be suspended and have small concave deformation.

[0055] Example 2

[0056] This application also discloses a magnetically responsive suspended droplet manipulation platform and a method for preparing the magnetically responsive suspended droplet manipulation platform. The difference between this method and the embodiment of Example 1 is that the material used to prepare the magnetically responsive suspended droplet manipulation platform can be other than silicone, but must meet the following requirements:

[0057] 1. The selected materials do not react with the template materials;

[0058] 2. The oil used does not swell with the material of the magnetically responsive suspended droplet control platform.

[0059] It should be noted that, in this document, the use of relational terms such as "first" and "second" is merely for distinguishing one entity or operation from another, and does not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetically responsive suspended droplet manipulation platform, characterized in that, It includes a silicone substrate (1), silicone micropillars (2) arranged in an array on the silicone substrate (1), and a silicone film (3) mounted on the top of the silicone micropillars (2), wherein the silicone substrate (1) and the silicone micropillars (2) are integrally formed; The diameter of the top end of the silicone micropillar (2) ranges from 100um to 180um; The method for preparing the magnetically responsive suspended droplet manipulation platform includes the following steps: S1. Fabrication of micro-via array template: Micro-vias distributed in an array are drilled on the template using a femtosecond laser. S2. Fabrication of micropillar array structure: S2.1 Preparation of mixed solution: The silica gel solution, magnetic particles and silicone oil are thoroughly mixed and stirred at a mass ratio of 1:1:0.1 to obtain a mixed solution; S2.

2. Apply the mixed solution evenly to the upper surface of the micro-hole array template, and evacuate until the mixed solution completely enters the interior of each micro-hole; S2.

3. The micro-via array template is vertically magnetized with a magnet. The magnetized micro-via array template is placed on a glass plate and allowed to cure naturally for 6 hours. The silicone cured by the mixed solution is then peeled off from the micro-via array template to obtain a micro-pillar array structure. The part of the micro-pillar array structure located on the surface of the micro-via array template is the silicone substrate (1), and the part located in the micro-vias on the micro-via array template is the silicone micro-pillar (2). S2.4 uses a femtosecond laser to perform direct writing operations on a micropillar array structure; S3. Silicone film preparation: After thoroughly mixing the silicone solution and silicone oil at a mass ratio of 1:0.1, pour the mixture onto the surface of a glass slide with adhesive tape, and spin-coat the mixture to obtain a silicone film (3). S4. Fabrication of magnetically responsive suspended droplet manipulation platform: The micropillar array structure is installed together with the silicone film (3), wherein the top of the silicone micropillar (2) is in contact with the silicone film (3), and after curing in the natural environment for 3 hours, it is peeled off from the surface of the glass slide to obtain the magnetically responsive suspended droplet manipulation platform. S5. Perform femtosecond laser direct writing on the silicone film (3) in the magnetic response suspended droplet manipulation platform, and then apply oil to the surface of the silicone film (3).

2. The magnetically responsive suspended droplet manipulation platform according to claim 1, characterized in that, In steps S2.1 and S3, the silicone solution is a solution in which silicone prepolymer and curing agent are mixed in a 1:1 mass ratio.

3. The magnetically responsive suspended droplet manipulation platform according to claim 1, characterized in that, In steps S2.4 and S5, the scanning parameters for the femtosecond laser direct writing operation are: number of scans: 1-3 times, laser power: 100~450mw, and scanning speed: 2~30mm / s.

4. The magnetically responsive suspended droplet manipulation platform according to claim 1, characterized in that, The template material in step S1 is either PTFE or PDMS.

5. The magnetically responsive suspended droplet manipulation platform according to claim 1, characterized in that, In step S3, the spin coating parameters are: rotation speed: 100~1000 rpm, duration: 1~3 min.

6. The magnetically responsive suspended droplet manipulation platform according to claim 1, characterized in that, In step S1, the thickness of the template is 1 mm.

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