Droplet transportation magnetic control film robot and preparation method and application thereof

Abstract

The invention relates to the technical field of micro-robots, in particular to a liquid drop transportation magnetic control film robot and a preparation method and application thereof. The liquid drop transportation magnetic control film robot comprises a connecting plate, movable plates are symmetrically arranged on the two sides of the connecting plate, and the ends, away from the connecting plate, of the movable plates can move towards the top of the connecting plate till the movable plates are gathered and adsorbed to the surfaces of liquid drops. The liquid drop transportation magnetic control film robot is simple in manufacturing process and convenient to drive; and accurate, efficient, rapid and long-distance fixed-point liquid drop conveying, sub-liquid drop distribution and liquid drop merging and stirring can be realized. The liquid drop transportation magnetic control film robot can work in an open microfluid environment, special customized surfaces such as an electrode array, namely a tiny flow channel, are not needed, and micro-liquid drop transportation can be achieved more flexibly.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-robots, and in particular to a droplet transporting magnetically controlled thin film robot and a preparation method and application thereof. Background Art

[0002] Directed transport of fluids is crucial to the development of analytical methods in modern analytical chemistry. There are two types of droplet directional transport strategies: active transport and passive transport. The main passive transport method relies on the surface energy gradient of the droplet on a specially processed surface. The droplet will move toward the area with higher wettability. The surface energy gradient depends on the chemical composition and surface roughness. The energy-driven driving force is limited, and it is very difficult to achieve long-distance and efficient transportation.

[0003] Active transport mainly relies on external driving force to move droplets, usually by applying external field induction or moving the carrier that carries the droplets to achieve active transport of droplets. Digital microfluidics has the advantages of less sample consumption, short detection and analysis time, and automated programming, but it also has many limitations. It requires liquids to work on a precisely customized micro-operation surface, and the production requires high costs.

[0004] Previous studies have mainly relied on special asymmetric structures, which inevitably have the problems of slow transmission speed and short distance. In order to improve controllability, researchers have tried to use external fields such as heat, light, electric fields and magnetic fields to achieve and design controllable transmission of droplets.

[0005] At present, there is a need to develop a robot that can achieve directional droplet delivery efficiently, accurately and at low cost, and minimize contact interference with the load. Summary of the invention

[0006] The first object of the present invention is to provide a droplet transporting magnetically controlled thin film robot, which can realize active directional transport of droplets efficiently, accurately and at low cost.

[0007] The second object of the present invention is to provide a method for preparing a droplet transporting magnetically controlled thin film robot.

[0008] The present invention provides a droplet transporting magnetically controlled thin film robot, comprising a connecting plate, wherein movable plates are symmetrically arranged on both sides of the connecting plate, and the movable plate is away from one end of the connecting plate and can move toward the top of the connecting plate until it gathers and is adsorbed on the droplet surface.

[0009] Preferably, the connection points between the connecting plate and the movable plate are both provided with rounded corners.

[0010] Preferably, the length-to-width ratio of the connecting plate and the movable plate is 1:1.

[0011] Preferably, the thickness of the connecting plate and the movable plate is 0.05-0.2 mm.

[0012] Preferably, the lower surface of the connecting plate and the movable plate is a superhydrophobic surface having an array of micro-nano protrusions similar to the surface of a lotus leaf, and droplets are in a Cassie state on the superhydrophobic surface; the upper surface of the connecting plate and the movable plate is a sub-hydrophobic surface.

[0013] The present invention also provides a method for preparing a droplet transport magnetically controlled thin film robot, comprising the following steps:

[0014] S1. Place the lotus leaf slice on the base material, cover it with silicone rubber, press it down and cure it, capture the super-hydrophobic microstructure characteristics of the lotus leaf surface, and obtain the silicone rubber mold after demolding;

[0015] S2. The rubber liquid and the magnetic particles are thoroughly mixed and degassed to obtain a magnetized rubber liquid;

[0016] S3. Pour the magnetized rubber liquid into the silicone rubber mold obtained in step S1, and heat and cure to obtain a film sheet;

[0017] S4. Cutting the film sheet by laser according to the set shape to obtain a robot model with an integrated structure;

[0018] S5. Use a magnetizer to magnetize the robot model, and obtain a droplet transport magnetron thin film robot after uniform magnetization.

[0019] Preferably, in step S2, the rubber liquid is polydimethylsiloxane, and the magnetic particles are neodymium iron boron.

[0020] Preferably, in step S2, the mass ratio between the rubber liquid and the magnetic particles is 1:(1.4-1.6).

[0021] Preferably, the magnetization direction of step S5 is parallel to the connecting edge of the connecting plate and the movable plate.

[0022] The present invention also provides the application of the droplet transporting magnetically controlled thin film robot in the field of droplet capture, rotation and sub-droplet release.

[0023] Beneficial effects:

[0024] The droplet transporting magnetic thin film robot of the present invention has a simple manufacturing process and is easy to drive; and can realize accurate, efficient, fast, long-distance fixed-point droplet transport, sub-droplet distribution, droplet merging and stirring. The droplet transporting magnetic thin film robot of the present invention can work in an open microfluidic environment, does not need to make a special customized surface such as an electrode array, that is, a tiny flow channel, and can achieve micro droplet transport more flexibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a schematic structural diagram of a droplet transporting magnetically controlled thin film robot in an unloaded state according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a fully loaded state of a droplet transporting magnetically controlled thin film robot according to an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the magnetization direction of a droplet transport magnetically controlled thin film robot according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of a silicone rubber mold in an embodiment of the present invention;

[0030] Figure 5 Schematic diagram of the structure of a three-dimensional Helmholtz coil of a driving source in an embodiment of the present invention;

[0031] Figure 6 Schematic diagram of the flipping and straight-moving motion mechanism of the droplet transporting magnetically controlled thin film robot according to an embodiment of the present invention.

[0032] 1-super hydrophobic surface, 2-sub hydrophobic surface, 3-groove, 4-rounded corner, 5-connecting plate, 6-movable plate. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Example

[0037] like Figure 1-2 As shown, a droplet transporting magnetically controlled thin film robot comprises a connecting plate 5, and movable plates 6 are symmetrically arranged on both sides of the connecting plate 5, and the connecting plate 5 and the movable plate 6 are an integrated structure. The lower surface of the connecting plate 5 and the movable plate 6 is a super hydrophobic surface 1, and the super hydrophobic surface 1 has a micro-nano protrusion array similar to the surface of a lotus leaf. The droplet is in a Cassie state on the super hydrophobic surface 1, and the surface contact angle between the droplet and the super hydrophobic surface 1 is greater than 150°; the upper surface of the connecting plate 5 and the movable plate 6 is a sub-hydrophobic surface 2. The super hydrophobic surface 1 has no adhesion to the droplet, and the droplet does not adhere to the super hydrophobic surface 1, which is convenient for adhering to another surface; it can also assist in the realization of the "droplet release" function.

[0038] The aspect ratio of the connecting plate 5 and the movable plate 6 is 1:1. The thickness of the connecting plate 5 and the movable plate 6 is 0.05-0.2mm. Preferably, the overall length of the robot is 9mm, the length and width of the connecting plate 5 and the movable plate 6 are both 3mm, and the thickness is 0.15mm. The super-hydrophobic surface 1 is provided with a groove 3 at the connection between the connecting plate 5 and the movable plate 6, the groove width is ≤200μm, the groove depth is ≤60μm, the movable plate 6 can be folded at the groove 3, no other rotating structure is required, and the movable plate 6 and the connecting plate 5 are an integrated structure, and the preparation process is simple. The connection between the connecting plate 5 and the movable plate 6 is provided with chamfers 4 on both sides of the groove 3, and the radius of the chamfer 4 is 1mm. The movable plate 6 can move to the side of the sub-hydrophobic surface 2 at the top of the connecting plate 5 away from the connecting plate 5 until it gathers and adsorbs to the surface of the droplet. After capturing the droplet, the sub-hydrophobic surface 2 is located on the inside, and the super-hydrophobic surface 1 is located on the outside, forming a state similar to a triangular prism as a whole.

[0039] The present invention provides a method for preparing a droplet transport magnetically controlled thin film robot, comprising the following steps:

[0040] S1. Place the lotus leaf slice on the base material, cover it with silicone rubber, press it down and solidify it, capture the super-hydrophobic microstructure characteristics of the lotus leaf surface, and obtain the silicone rubber mold after demoulding (such as Figure 4 As shown), the mold depth is the same as the thickness of the connecting plate 5;

[0041] S2. The rubber liquid polydimethylsiloxane and the magnetic particles neodymium iron boron are fully mixed in a mass ratio of 1:1.5, and the magnetized rubber liquid is obtained after degassing; polydimethylsiloxane is a high-performance silicon-based polymer with excellent elasticity, fatigue resistance, and biocompatibility, and is an ideal medical device material. Neodymium iron boron (NdFeB), as a rare earth magnetic material, has extremely high magnetic field strength and stability, which can ensure that the film robot maintains excellent magnetic properties in complex environments, especially under high temperature conditions, and can still effectively exert its magnetic properties.

[0042] S3. The magnetized rubber liquid is poured into the silicone rubber mold obtained in step S1, and the film is obtained after heating and curing;

[0043] The bottom of the film sheet is plasticized by a silicone rubber mold to obtain a super-hydrophobic surface. The droplets on the super-hydrophobic surface 1 are in a Cassie state. The surface contact angle between the droplets and the super-hydrophobic surface 1 is greater than 150°. This characteristic can be used to assist in separating the droplets. After the top of the film sheet is cured, a flat surface is obtained. The flat surface is a sub-hydrophobic surface 2. Its hydrophobic performance is determined by the surface characteristics of the magnetized rubber liquid after curing. Its adhesion is greater than that of the super-hydrophobic surface 1. The contact angle of the droplets on the sub-hydrophobic surface 2 is greater than 90° but less than 150°. The droplets can maintain a certain shape on it, but are not as easy to roll as on the super-hydrophobic surface 1. This characteristic can be used to guide the movement path of the droplets and capture the droplets.

[0044] S4. According to the set shape, the film is cut by laser, and the groove 3 and the rounded corner 4 are cut on the film to obtain an integrated structure of the robot model;

[0045] S5. Use a magnetizer to magnetize the robot model, and the magnetization direction is parallel to the axis of groove 3 (such as Figure 3 As shown in the figure, a droplet transport magnetron thin film robot is obtained after uniform magnetization. The robot is magnetized as a whole, and the magnetization direction is along the axis direction of groove 3, and it moves under the driving control of the rotating magnetic field generated by the Holm Hertz coil. The unique unidirectional magnetization method is adopted, combined with the periodic magnetic field change, so that the thin film robot can dynamically adjust its shape, thereby realizing the efficient operation of droplet capture, separation and mixing. This magnetization method simplifies the production process and improves the flexibility of the robot in liquid operation.

[0046] The droplet transport magnetically controlled thin film robot proposed in the present invention can be transported by a three-dimensional Helmholtz coil (such as Figure 5 The rotating magnetic field generated by the external field drive control is flipped and moved straight (as shown in Figure 6The three-dimensional Helmholtz coils can generate magnetic fields independently in the three directions of the X, Y, and Z axes, that is, each set of Helmholtz coils can drive a magnetic field in an axial direction alone. When two or more sets of Helmholtz coils are enabled at the same time, magnetic fields in any direction can be generated in a two-dimensional or three-dimensional plane, thereby enabling the film robot to move in multiple directions.

[0047] Driven by the Helmholtz coil, the robot can complete three action modes: droplet capture, carrier liquid rotation, and sub-droplet distribution / release. The methods for driving the robot to complete different actions are as follows:

[0048] The specific driving method for driving the droplet transport magnetron thin film robot to complete "droplet capture" is: first, the rotating magnetic field generated by the Helmholtz coil is used to control the thin film robot to reverse and move forward to the vicinity of the droplet, with the sub-hydrophobic surface 2 close to the droplet and the super-hydrophobic surface 1 located above. After contact, the droplet is adsorbed to the sub-hydrophobic surface 2 on the lower surface due to capillary force, and the thin film robot then folds and deforms along the groove 3 to wrap the droplet, completing the capture of the droplet.

[0049] The Helmholtz coil is moved, and the fully loaded film robot rolls until it reaches the predetermined target point, completing the active transport of the droplets.

[0050] The film robot of the present invention captures droplets by the adhesion of the sub-hydrophobic surface 2 and the surface tension of the droplets. The other surface of the film robot is a super-hydrophobic surface 1, which has no adhesion to the droplets and can assist in the realization of the "droplet release" function.

[0051] The specific driving method for driving the droplet transporting magnetically controlled thin film robot to complete the "liquid carrier rotation" is as follows: after capturing the droplets, the thin film robot is in a fully loaded state, and then the Helmholtz coil applies a rotating magnetic field from bottom to top, and the robot rotates synchronously with the rotation direction to complete the liquid carrier rotation action.

[0052] The specific driving method for driving the droplet transport magnetically controlled thin film robot to complete the "sub-droplet distribution / release" is: increase the magnetic field in the magnetization direction of the robot, continue to fold and press down at the groove 3 of the thin film robot, and the droplet is squeezed out to complete the release of the droplet. This magnetic field control method is accurate and efficient, and can achieve precise processing and manipulation of droplets in a microfluidic environment. It has great application value in the fields of biomedicine, chemical synthesis, etc., and can effectively improve the accuracy and efficiency of related experiments and production.

[0053] Through the dynamic changes of the external magnetic field, the thin-film robot can achieve precise droplet capture and sub-droplet separation operations. The robot achieves precise droplet capture by adjusting the magnetic field strength, and in the droplet separation operation, the robot achieves precise separation and rotation of droplets through micro-nanostructure design and periodic magnetic field guidance.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A droplet transport magnetically controlled thin film robot, characterized in that: It comprises a connecting plate, and movable plates are symmetrically arranged on both sides of the connecting plate. One end of the movable plate away from the connecting plate can move toward the top of the connecting plate until it gathers and is adsorbed on the surface of the droplet.

2. The droplet transporting magnetic control thin film robot according to claim 1, characterized in that: The connection points between the connecting plate and the movable plate are both provided with rounded corners.

3. The droplet transporting magnetically controlled thin film robot according to claim 1, characterized in that: The length-to-width ratios of the connecting plate and the movable plate are both 1:

1.

4. The droplet transporting magnetically controlled thin film robot according to claim 1, characterized in that: The thickness of the connecting plate and the movable plate is 0.05-0.2 mm.

5. The droplet transporting magnetic control thin film robot according to claim 1, characterized in that: The lower surface of the connecting plate and the movable plate is a super-hydrophobic surface having a micro-nano protrusion array similar to the surface of a lotus leaf, and the droplets on the super-hydrophobic surface are in a Cassie state; the upper surface of the connecting plate and the movable plate is a sub-hydrophobic surface.

6. A method for preparing a droplet transporting magnetically controlled thin film robot according to claims 1-5, characterized in that: The following steps are involved: S1. Place the lotus leaf slice on the base material, cover it with silicone rubber, press it down and cure it, capture the super-hydrophobic microstructure characteristics of the lotus leaf surface, and obtain the silicone rubber mold after demolding; S2. The rubber liquid and the magnetic particles are thoroughly mixed and degassed to obtain a magnetized rubber liquid; S3. Pour the magnetized rubber liquid into the silicone rubber mold obtained in step S1, and heat and cure to obtain a film sheet; S4. Cutting the film sheet by laser according to the set shape to obtain a robot model with an integrated structure; S5. Use a magnetizer to magnetize the robot model, and obtain a droplet transport magnetron thin film robot after uniform magnetization.

7. The method for preparing a droplet transporting magnetically controlled thin film robot according to claim 6, characterized in that: In the step S2, the rubber liquid is polydimethylsiloxane, and the magnetic particles are neodymium iron boron.

8. The method for preparing a droplet transporting magnetically controlled thin film robot according to claim 6, characterized in that: The mass ratio between the rubber liquid and the magnetic particles in the step S2 is 1:(1.4-1.6).

9. The method for preparing a droplet transporting magnetically controlled thin film robot according to claim 6, characterized in that: The magnetization direction of step S5 is parallel to the connection edge of the connecting plate and the movable plate.

10. Application of the droplet transporting magnetically controlled thin film robot according to claims 1-5 in the field of droplet capture, rotation and sub-droplet release.

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