CN117463415B - High-flux micro-droplet control method and device - Google Patents

Abstract

The present invention discloses a high-throughput micro-droplet manipulation method and device, the method comprising: S1, placing a super-hydrophobic insulating film on an upper portion of a support platform with an opening, the lower portion of the support platform also being provided with a removable insulating mask, the insulating mask having a hole structure; S2, spraying conductive micro-droplets on the upper surface of the super-hydrophobic insulating film, subsequently forming a surface electrostatic potential well at the upper end of the super-hydrophobic insulating film, and merging the micro-droplets under the action of the surface electrostatic potential well; S3, controlling the mask to move, guiding the micro-droplets to be manipulated to move to a target position, removing the surface electrostatic potential well and causing the micro-droplets to be separated from the upper surface of the super-hydrophobic insulating film. The materials used in the present invention are highly versatile, the device is simple and easy to obtain, and there is no external additive, which reduces the manufacturing cost of high-throughput micro-droplet manipulation, improves the flexibility of micro-droplet manipulation, and avoids the contamination of micro-droplets to be manipulated.

Description

A high-throughput micro-droplet manipulation method and device

Technical Field

The present invention relates to the field of micro-droplet manipulation technology, and in particular to a high-throughput micro-droplet manipulation method and device.

Background Art

High-throughput droplet manipulation technology is crucial for fields such as biological detection, chemical synthesis, and industrial production, such as virus enrichment detection, precise control of chemical reactions, and 3D printing.

Existing high-throughput droplet manipulation technologies are mostly based on microchannels and electrowetting. However, microchannel technology, due to its fixed channel structure and high machining precision requirements, has high manufacturing costs, is non-reconfigurable, and is prone to clogging. Electrowetting technology, due to the complex design of components such as electrodes, high integration, and easily degraded hydrophobic dielectric (electrical insulation) surfaces, has high design costs, is prone to short circuits, and is difficult to apply to applications involving random droplet distribution. Reducing manufacturing costs, increasing droplet manipulation throughput, and reconfigurability are areas where improvement and development are needed in droplet manipulation technology.

With the development of increasingly efficient and controllable electricity, the combination of electrical stimulation and microfluidics has produced electrofluidics. The application of charged surfaces to achieve high-throughput droplet manipulation is expected to expand and improve existing droplet manipulation methods.

Summary of the Invention

In order to solve the problems existing in the prior art, the present invention provides a high-throughput micro-droplet manipulation method, comprising the following steps:

S1. Placing a super-hydrophobic insulating film on an upper portion of a support platform with an opening, wherein a movable insulating mask having a hole structure is further provided on the lower portion of the support platform;

S2, spraying conductive micro-droplets on the upper surface of the super-hydrophobic insulating film, then forming a surface electrostatic potential well on the upper end of the super-hydrophobic insulating film, and causing the micro-droplets to merge under the action of the surface electrostatic potential well;

S3, controlling the movement of the mask to guide the micro-droplet to be manipulated to move to a target position, removing the surface electrostatic potential well and separating the micro-droplet from the upper surface of the super-hydrophobic insulating film.

Furthermore, the super-hydrophobic insulating film is obtained by immersing the insulating film in a hydrophobic liquid for hydrophobic treatment;

The insulating film is formed by polymerizing fiber materials and has a microporous structure with a pore diameter of 5 to 15 μm and a thickness of 50 to 150 μm.

Furthermore, the insulating mask is obtained by etching a hole structure from a non-porous dense insulating film.

Furthermore, the pore structure includes a regular array structure and a random distribution structure.

Furthermore, the surface electrostatic potential well is generated by corona discharge of two needle-tip electrodes connected to the positive and negative poles of the power supply, and positive and negative charges are deposited on the super-hydrophobic insulating film, wherein the distance between the needle-tip electrode connected to the positive pole of the power supply and the super-hydrophobic insulating film is greater than the distance between the needle-tip electrode connected to the negative pole of the power supply and the super-hydrophobic insulating film, such a distance setting allows negative charges to penetrate the super-hydrophobic insulating film and be captured by it, thereby depositing on the super-hydrophobic insulating film to form a pattern composed of positive and negative charges, thereby forming a surface electrostatic potential well;

The needle tip electrode is made of a conductive solid material.

Furthermore, the power supply voltage can range from +5 to 20 kV. However, it should be noted that voltages above 5 kV can cause corona discharge at the needle tip, generating charge. This charge deposits on the hydrophobic insulating film, forming a surface electrostatic potential well. Charged droplets are attracted by the electrostatic attraction and move to areas of lower potential. It should be noted that the actual power supply voltage is not limited to +5 to 20 kV.

The present invention also provides a high-throughput micro-droplet manipulation device, comprising a super-hydrophobic insulating film, a support platform with an opening, a mask with a hole structure, a moving mechanism, a power supply, an electrode, a support platform fixing component, and an electrode bracket;

The support platform is fixed to the upper end of the moving mechanism by a support platform fixing member;

The super-hydrophobic insulating film is placed on the upper opening of the support platform;

The mask is fixed to the lower part of the opening of the support platform by the moving mechanism;

The electrodes include a positive electrode connected to the positive electrode of the power supply and a negative electrode grounded;

The electrode support comprises a positive electrode support and a negative electrode support, wherein the positive electrode support and the negative electrode support respectively fix the positive electrode on the upper end of the super-hydrophobic insulating film and fix the negative electrode on the end away from the support platform.

Furthermore, a baffle is provided at the lower end of the mask, and the baffle is fixed to the upper end of the moving mechanism.

Furthermore, the positive electrode and the negative electrode are needle-tip structures with a pointed top and a narrow bottom.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention combines an insulating mask with a porous structure that can block the penetration of positive/negative charges with a super-hydrophobic insulating film to customize the charge array pattern deposited on the surface of the super-hydrophobic insulating film. Due to the high resolution of the deposited charges, the control accuracy is high and the flexibility is good. The method of the present invention uses a moving mechanism to control the movement of the mask, realizing programmable and non-contact high-throughput micro-droplet manipulation. In addition, the materials used in the present invention are highly versatile, the device is simple and easy to obtain, and no external additives are required, which reduces the manufacturing cost of high-throughput micro-droplet manipulation, improves the flexibility of micro-droplet manipulation, and avoids contamination of the micro-droplets to be manipulated.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 shows a schematic structural diagram of a high-throughput micro-droplet manipulation device according to Example 1 of the present invention;

FIG2 shows a flow chart of a high-throughput micro-droplet manipulation method according to Example 2 of the present invention;

FIG3 shows a schematic diagram of parallel manipulation of micro-droplets according to Example 2 of the present invention;

FIG4 shows a schematic diagram of parallel manipulation of micro-droplets according to Example 3 of the present invention;

FIG5 is a schematic diagram showing high-throughput droplet transport according to Example 4 of the present invention;

Description of reference numerals:

1. Positive needle tip electrode; 2. Micro droplets to be manipulated; 3. Super hydrophobic insulating film; 4. Support platform; 5. Mask with microhole array structure; 6. Negative needle tip electrode; 7. Moving mechanism; 8. Baffle; 9. Power supply.

DETAILED DESCRIPTION

The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only applicable to illustrative descriptions and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the specific embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Example 1

As shown in Figure 1, a high-throughput micro-droplet manipulation device includes a super-hydrophobic insulating film 3, a support platform 4 with an opening structure, a mask 5 with a micropore array structure, a baffle 8, a moving mechanism 7, a power supply 9, a positive needle-tip electrode 1, a negative needle-tip electrode 6, a positive bracket, a fixing component of the support platform 4, and a negative bracket. The support platform 4 with an opening structure is fixed to the upper end of the moving mechanism 7 by the fixing component of the support platform 4, and the super-hydrophobic insulating film 3 is placed above the opening of the support platform 4; the upper end of the moving mechanism 7 is fixed with a baffle 8 and a mask 5 with a micropore array structure from bottom to top, and the mask 5 with a micropore array structure is located below the opening of the support platform 4 with an opening. The positive needle-tip electrode 1 and the negative needle-tip electrode 6 are respectively connected to the positive and negative poles of the power supply 9. The positive bracket and the negative bracket respectively fix the positive electrode to the upper end of the super-hydrophobic insulating film 3 and the negative electrode to the end away from the support platform 4. The negative needle-tip electrode 6 is also grounded.

When using the device, conductive micro-droplets are sprayed on the upper surface of the super-hydrophobic insulating film 3 to form micro-droplets 2 to be manipulated, and then the power is turned on to form a surface electrostatic potential well on the super-hydrophobic insulating film 3. Under the action of the surface electrostatic potential well, the micro-droplets 2 to be manipulated are fused; the movement of the mask is controlled to guide the micro-droplets 2 to be manipulated to move to the target position, remove the surface electrostatic potential well, and allow the manipulated micro-droplets to detach from the surface of the super-hydrophobic insulating film 3.

The super-hydrophobic insulating film 3 can be obtained by immersing an insulating film with a thickness of 50 to 150 μm in a hydrophobic liquid for hydrophobic treatment.

The insulating mask with a hole structure can be obtained by etching the hole structure from a non-porous dense insulating material. Regular or randomly distributed hole structures can be etched from the non-porous dense insulating material by laser direct writing or other processes. The regular array can be of various shapes, such as equidistant, equidistant, or proportional spacing, such as linear (including curved, straight, or a combination of straight and curved lines), circular, square, and other polygonal shapes. Random distribution is not strictly limited, as long as it can be etched using existing etching processes.

Among them, the material of the needle tip electrode is a conductive solid material, which can be a common material such as copper, steel, carbon fiber, etc. The voltage that the power supply 9 can provide can be +5~20kV. The distance between the needle tip electrode connected to the positive pole of the power supply and the super-hydrophobic insulating film is greater than the distance between the needle tip electrode connected to the negative pole of the power supply and the super-hydrophobic insulating film. The distances can be 50mm and 10mm respectively. Of course, it is not limited to this distance. When actually selected, it can be adjusted according to parameters such as the pore size, thickness, area and voltage of the super-hydrophobic insulating film.

The super-hydrophobic insulating film 3 can be placed on the support platform 4 in a randomly distributed direction, and can be placed horizontally, at an angle to the horizontal direction, vertically, or curved.

The moving mechanism 7 can move randomly or according to a preset moving trajectory, such as expansion and contraction and rotation in a direction parallel to the plane of the super-hydrophobic insulating film 3 .

Example 2

A high-throughput micro-droplet manipulation method, based on the apparatus of Example 1, as shown in FIG2 , comprises the following steps:

S1. Preparation of a super-hydrophobic insulating film: A polypropylene film with a diameter of 90 mm and a thickness of 150 μm was fully immersed in dimethyl silicone oil with a viscosity of 50 cSt and a density of 0.96 g/cm ³ , and then taken out and allowed to stand for 5 minutes to obtain a super-hydrophobic insulating film;

S2. Preparing an insulating mask with a microhole array structure: using a laser direct writing process to etch an equidistant circular hole array structure on a square piece of organic glass to obtain an insulating mask with a microhole array structure;

S3. Installing the micro-droplet manipulation device: The method of Example 1 can be referred to and will not be described in detail here;

S4, micro-droplet array: Use a nano-sprayer to spray micro-droplets on the upper surface of the super-hydrophobic insulating film, then turn on the power and adjust the voltage to 9kV. Utilize the electrostatic attraction between the circular array area on the upper surface of the super-hydrophobic insulating film that is not blocked by the mask and the micro-droplets to be manipulated, drive the micro-droplets close to the circular array area, merge and form a micro-droplet array, and the micro-droplet array form is consistent with the hole array on the mask, as shown in Figure 3;

S5. Parallel movement of micro-droplets: The insulating mask with the micro-hole array structure is controlled by a moving mechanism to move in a plane parallel to the super-hydrophobic insulating film. The electrostatic attraction between the new circular array area on the upper surface of the super-hydrophobic insulating film that is not blocked by the insulating mask with the micro-hole array structure and the droplet array to be manipulated is used to guide the micro-droplet array to move directionally to the target position. The parallel form of the micro-droplet array is still consistent with the hole array on the mask, as shown in Figure 3;

S6. Release of micro-droplets: Turn off the power supply to remove the surface electrostatic potential well on the upper end of the super-hydrophobic insulating film, thereby eliminating the electrostatic attraction between the circular array area on the upper surface of the super-hydrophobic insulating film that is not blocked by the insulating mask with a hole structure and the droplets to be manipulated, and release the droplet array to be manipulated.

Example 3

A high-throughput micro-droplet manipulation method is basically the same as Example 1, except that the structure of the insulating mask with a hole structure used is an array of circular holes of different sizes distributed in a ring shape, and the diameters of the circular holes distributed in the ring shape from the center to the outside are 2.5 mm, 2 mm and 1.5 mm respectively.

The results show that by adjusting the size and distribution of the circular holes on the insulating mask with a microhole array structure, the distribution of the deposited charge pattern on the membrane and the range of microdroplets that can be driven by a single microhole can be changed. This allows randomly distributed microdroplets on the membrane to be driven toward the nearest circular hole, where they merge and form an array pattern consistent with the mask. As shown in Figure 4, the final diameters of the droplets in the circular array were 2.4 mm, 1.8 mm, and 1.4 mm, respectively. This preliminary experiment demonstrates that this method can be used for high-throughput and rapid production of size-adjustable droplets.

Example 4

A high-throughput micro-droplet manipulation method is basically the same as Example 1, except that: 1. The super-hydrophobic insulating film is placed on a support table at a 45° tilt from the horizontal direction; 2. The insulating mask with a micropore array structure is an equidistant circular hole strip array structure (similar to a strip channel with a width of 2mm), and a micro-injection pump is placed at the entrance of the strip channel to produce continuous micro-droplets to be manipulated, with a micro-droplet volume of 2μL. As shown in Figure 5, the mask with a strip channel pattern limits charge penetration, so that a strip channel deposits a charge pattern on the super-hydrophobic insulating film, thereby causing continuous droplets to slide down the film surface under the action of gravity while being attracted by the electrostatic attraction from the strip channel area on the film surface and sliding down the strip channel to achieve high-throughput droplet transmission.

Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims (7)

1. A high-throughput micro-droplet manipulation method, characterized in that it comprises the following steps: S1. Placing a super-hydrophobic insulating film on an upper portion of a support platform with an opening, wherein a movable insulating mask having a hole structure is further provided on the lower portion of the support platform; S2, spraying conductive micro-droplets on the upper surface of the super-hydrophobic insulating film, then forming a surface electrostatic potential well on the upper end of the super-hydrophobic insulating film, and causing the micro-droplets to merge under the action of the surface electrostatic potential well; S3, controlling the movement of the mask to guide the micro-droplet to be manipulated to move to a target position, removing the surface electrostatic potential well and separating the micro-droplet from the upper surface of the super-hydrophobic insulating film; The insulating film has a thickness of 50-150 μm and a microporous structure with a pore size of 5-15 μm; The surface electrostatic potential well is generated by corona discharge of two needle-tip electrodes connected to the positive and negative poles of the power supply, and the positive and negative charges are deposited on the super-hydrophobic insulating film. The distance between the needle tip electrode connected to the positive electrode of the power supply and the super-hydrophobic insulating film is greater than the distance between the needle tip electrode connected to the negative electrode of the power supply and the super-hydrophobic insulating film; The needle tip electrode is made of a conductive solid material. 2. The high-throughput micro-droplet manipulation method according to claim 1, wherein the super-hydrophobic insulating film is obtained by immersing the insulating film in a hydrophobic liquid for hydrophobic treatment; The insulating film is formed by polymerizing fiber materials. 3 . The high-throughput micro-droplet manipulation method according to claim 2 , wherein the insulating mask is obtained by etching a pore structure from a non-porous dense insulating film. 4 . The high-throughput micro-droplet manipulation method according to claim 3 , wherein the pore structure comprises a regular array structure and a random distribution structure. 5. A device for implementing the high-throughput micro-droplet manipulation method according to any one of claims 1 to 4, characterized in that it comprises a super-hydrophobic insulating film, a support platform with an opening, a mask with a hole structure, a moving mechanism, a power supply, an electrode, a support platform fixing component, and an electrode bracket; The support platform is fixed to the upper end of the moving mechanism by a support platform fixing member; The super-hydrophobic insulating film is placed on the upper opening of the support platform; The mask is fixed to the lower part of the opening of the support platform by the moving mechanism; The electrodes include a positive electrode connected to the positive electrode of the power supply and a negative electrode grounded; The electrode support comprises a positive electrode support and a negative electrode support, wherein the positive electrode support and the negative electrode support respectively fix the positive electrode on the upper end of the super-hydrophobic insulating film and fix the negative electrode on the end away from the support platform. 6 . The device according to claim 5 , wherein a baffle is further provided at the lower end of the mask, and the baffle is fixed to the upper end of the moving mechanism. 7. The device according to claim 5, characterized in that the positive electrode and the negative electrode are needle-tip structures with a pointed top and a narrow bottom.