A droplet transport magnetically controlled thin-film robot, its preparation method and application

Abstract

This invention relates to the field of microrobot technology, and in particular to a droplet transport magnetically controlled thin-film robot, its preparation method, and its applications. The droplet transport magnetically controlled thin-film robot includes a connecting plate with symmetrically arranged movable plates on both sides. The movable plates, located away from the connecting plate, can move towards the top of the connecting plate until they converge and adhere to the droplet surface. The droplet transport magnetically controlled thin-film robot of this invention has a simple manufacturing process and is easy to drive; it can achieve accurate, efficient, rapid, and long-distance fixed-point droplet transport, sub-droplet distribution, droplet merging, and stirring. The droplet transport magnetically controlled thin-film robot of this invention can operate in an open microfluidic environment, without requiring specially customized surfaces such as electrode arrays or tiny flow channels, enabling more flexible microdroplet transport.

Description

Technical Field

[0001] This invention relates to the field of microrobot technology, and in particular to a droplet transport magnetically controlled thin-film robot, its preparation method, and its application. Background Technology

[0002] Directional transport of fluids is crucial for the development of analytical techniques in modern analytical chemistry. Droplet directional transport strategies are divided into active and passive transport. Passive transport primarily relies on the surface energy gradient of a droplet on a specially processed surface. The droplet will move towards areas of higher wettability. However, the surface energy gradient depends on the chemical composition and surface roughness, and the energy-driven force is limited, making it very difficult to achieve long-distance and efficient transport.

[0003] Active transport relies primarily on external driving forces to move droplets, typically achieved by applying an external field to induce movement or by using a carrier to move the droplets. Digital microfluidics offers advantages such as low sample consumption, short detection and analysis times, and automated programming, but it also has many limitations, including the need for liquids to operate on precisely customized micromanipulation surfaces and the high cost of manufacturing them.

[0004] Previous studies have mainly relied on special asymmetric structures, which inevitably suffer from slow transmission speeds and short distances. To improve controllability, researchers have attempted to use external fields, such as heat, light, electric fields, and magnetic fields, to achieve and design controllable droplet transmission.

[0005] Currently, there is a need to develop a robot that can efficiently, accurately, and cost-effectively achieve directional delivery of droplets, minimizing contact interference with the load. Summary of the Invention

[0006] The first objective of this invention is to provide a magnetically controlled thin-film robot for droplet transport, which can achieve efficient, precise and low-cost active directional transport of droplets.

[0007] The second objective of this invention is to provide a method for preparing a droplet transport magnetically controlled thin-film robot.

[0008] The present invention provides a magnetically controlled thin-film robot for droplet transport, comprising a connecting plate, wherein movable plates are symmetrically arranged on both sides of the connecting plate, and the movable plates can move toward the top of the connecting plate at the end away from the connecting plate until they converge and adsorb onto the surface of the droplets.

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

[0010] Preferably, the aspect 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 surfaces of the connecting plate and the movable plate are superhydrophobic surfaces, which have an array of micro-nano protrusions resembling lotus leaf surfaces, and the droplets are in a Cassie state on the superhydrophobic surfaces; the upper surfaces of the connecting plate and the movable plate are subhydrophobic surfaces.

[0013] This invention also provides a method for fabricating a droplet transport magnetically controlled thin-film robot, comprising the following steps:

[0014] S1. Place lotus leaf slices on the substrate material, cover with silicone rubber, press down and cure to capture the superhydrophobic microstructure features of the lotus leaf surface, and obtain a silicone rubber mold after demolding.

[0015] S2. The rubber liquid and magnetic particles are thoroughly mixed and uniformly, and then degassed to obtain the magnetized rubber liquid.

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

[0017] S4. The thin film is laser-cut according to the set shape to obtain an integrated robot model;

[0018] S5. Magnetize the robot model using a magnetizer. After uniform magnetization, a droplet transport magnetically controlled thin-film robot is obtained.

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

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

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

[0022] This invention also provides the application of a magnetically controlled thin-film robot for droplet transport in the fields of droplet capture, rotation, and sub-droplet release.

[0023] Beneficial effects:

[0024] The droplet transport magnetically controlled thin-film robot of this invention has a simple manufacturing process and is easy to drive; it can achieve accurate, efficient, fast, and long-distance fixed-point droplet transport, sub-droplet distribution, droplet merging, and stirring. The droplet transport magnetically controlled thin-film robot of this invention can operate in an open microfluidic environment without the need to fabricate specially customized surfaces such as electrode arrays or tiny flow channels, enabling more flexible microdroplet transport. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the unloaded structure of the droplet transport magnetic thin-film robot according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the fully loaded form of the droplet transport magnetic thin film robot according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the magnetization direction of the droplet transport magnetic thin-film robot according to an embodiment of the present invention;

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

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

[0031] Figure 6 This is a schematic diagram of the flipping and straight-line motion mechanism of the droplet transport magnetically controlled thin-film robot according to an embodiment of the present invention.

[0032] 1-Superhydrophobic surface, 2-Subhydrophobic surface, 3-Groove, 4-Rounded corner, 5-Connecting plate, 6-Modible plate. Detailed Implementation

[0033] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all 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.

[0036] Example

[0037] like Figure 1-2 As shown, a droplet transport magnetically controlled thin-film robot includes a connecting plate 5, with movable plates 6 symmetrically arranged on both sides of the connecting plate 5. The connecting plate 5 and the movable plates 6 are an integrated structure. The lower surface of the connecting plate 5 and the movable plates 6 is a superhydrophobic surface 1, which has an array of micro-nano protrusions resembling a lotus leaf surface. The droplet is in a Cassie state on the superhydrophobic surface 1, and the surface contact angle between the droplet and the superhydrophobic surface 1 is greater than 150°. The upper surface of the connecting plate 5 and the movable plates 6 is a semi-hydrophobic surface 2. The superhydrophobic surface 1 has no adhesion to the droplet, and the droplet does not adhere to the superhydrophobic surface 1, which facilitates adhesion to another surface; it also assists in the realization of the "droplet release" function.

[0038] The aspect ratio of both the connecting plate 5 and the movable plate 6 is 1:1. The thickness of both the connecting plate 5 and the movable plate 6 is 0.05-0.2 mm. Preferably, the overall length of the robot is 9 mm, the length and width of both the connecting plate 5 and the movable plate 6 are 3 mm, and the thickness is 0.15 mm. A groove 3 is formed at the connection between the connecting plate 5 and the movable plate 6 on the superhydrophobic surface 1. The groove width is ≤200 μm and the groove depth is ≤60 μm. The movable plate 6 can fold at the groove 3 without the need for other rotating structures. Furthermore, the movable plate 6 and the connecting plate 5 are an integrated structure, simplifying the manufacturing process. Rounded corners 4 with a radius of 1 mm are provided on both sides of the groove 3 at the connection between the connecting plate 5 and the movable plate 6. The end of the movable plate 6 away from the connecting plate 5 can move towards the top of the connecting plate 5 towards the subhydrophobic surface 2 until it gathers and adsorbs onto the droplet surface. After capturing the droplet, the subhydrophobic surface 2 is located on the inner side, and the superhydrophobic surface 1 is located on the outer side, forming an approximately triangular prism shape.

[0039] This invention provides a method for fabricating a droplet transport magnetically controlled thin-film robot, comprising the following steps:

[0040] S1. Place lotus leaf slices on a substrate material, cover with silicone rubber, press down and cure to capture the superhydrophobic microstructure characteristics of the lotus leaf surface, and obtain a silicone rubber mold after demolding (e.g., Figure 4 (As shown), the mold depth is the same as the thickness of the connecting plate 5;

[0041] S2. A magnetized rubber liquid is prepared by thoroughly mixing polydimethylsiloxane (PDS) and neodymium iron boron (NdFeB) magnetic particles at a mass ratio of 1:1.5, followed by degassing. PDS is a high-performance silicon-based polymer with excellent elasticity, fatigue resistance, and biocompatibility, making it an ideal material for medical devices. NdFeB, as a rare-earth magnetic material, possesses extremely high magnetic field strength and stability, ensuring that thin-film robots maintain excellent magnetic properties in complex environments, especially effectively utilizing its magnetic characteristics under high-temperature conditions.

[0042] S3. Pour the magnetized rubber liquid into the silicone rubber mold obtained in step S1, and heat it to cure to obtain a thin film.

[0043] The bottom of the thin film is molded from silicone rubber to form a superhydrophobic surface. Droplets on the superhydrophobic surface 1 are in a Cassie state, and the contact angle between the droplet and the surface of the superhydrophobic surface 1 is greater than 150°. This property can be used to assist in the separation of droplets. After the top of the thin film is cured, a plane is formed, which is a semi-hydrophobic surface 2. Its hydrophobic properties are determined by the surface characteristics of the magnetized rubber liquid after curing. Its adhesion is greater than that of the superhydrophobic surface 1. The contact angle of the droplet on the semi-hydrophobic surface 2 is greater than 90° but less than 150°. The droplet can maintain a certain shape on it, but it is not as easy to roll as it is on the superhydrophobic surface 1. This property can be used to guide the movement path of the droplet and capture the droplet.

[0044] S4. Cut a thin film using a laser according to the set shape, and cut grooves 3 and rounded corners 4 on the thin film to obtain an integrated robot model;

[0045] S5. Magnetize the robot model using a magnetizer, with the magnetization direction parallel to the axis of groove 3 (e.g., ...). Figure 3 As shown, a droplet transport magnetically controlled thin-film robot is obtained after uniform magnetization. The robot is magnetized as a whole, with the magnetization direction along the axis of groove 3, and moves under the drive and control of the rotating magnetic field generated by the Helmholtz coil. A unique unidirectional magnetization method, combined with periodic magnetic field changes, enables the thin-film robot to dynamically adjust its shape, thereby achieving efficient droplet capture, separation, and mixing. This magnetization method simplifies the production process and improves the robot's flexibility in liquid handling.

[0046] The droplet transport magnetically controlled thin-film robot proposed in this invention can be transported via a three-dimensional Helmholtz coil (such as...). Figure 5 The rotating magnetic field generated (as shown) is used for external field drive control to flip and move straight (as shown). Figure 6(As shown). This three-dimensional Helmholtz coil can independently generate magnetic fields in the X, Y, and Z axes, meaning each set of Helmholtz coils can drive a magnetic field in one axial direction independently. When two or more sets of Helmholtz coils are activated simultaneously, magnetic fields in arbitrary directions can be generated in a two-dimensional or three-dimensional plane, enabling the thin-film robot to move in multiple directions.

[0047] Driven by Helmholtz coils, this robot can perform three action modes: droplet capture, liquid-carrying rotation, and sub-droplet distribution / release. The specific methods for driving the robot to perform these different actions are as follows:

[0048] The specific driving method for the magnetically controlled thin-film robot to complete the "droplet capture" is as follows: First, the rotating magnetic field generated by the Helmholtz coil controls the thin-film robot to move in reverse and move to the vicinity of the droplet. The subhydrophobic surface 2 approaches the droplet, and the superhydrophobic surface 1 is located above. After contact, the droplet is adsorbed onto the lower subhydrophobic surface 2 due to capillary force. The thin-film robot then folds and deforms along the groove 3 to wrap the droplet, thus completing the droplet capture.

[0049] The Helmholtz coil moves, and the fully loaded thin-film robot tumbles until it reaches the predetermined target point, completing the active transport of the droplets.

[0050] The thin-film robot of this invention captures droplets through the adhesion of the subhydrophobic surface 2 and the surface tension of the droplets. The other surface of the thin-film robot is a superhydrophobic surface 1, which has no adhesion to droplets and can assist in the realization of the "droplet release" function.

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

[0052] The specific driving method for the magnetically controlled thin-film robot to complete the "sub-droplet distribution / release" is as follows: The magnetic field in the direction of magnetization of the robot is increased, and the robot continues to fold downwards at groove 3, squeezing out the droplet and completing its release. This magnetic field control method is precise and efficient, enabling accurate handling and manipulation of droplets in microfluidic environments. It has significant application value in fields such as biomedicine and chemical synthesis, effectively improving the precision and efficiency of related experiments and production.

[0053] By dynamically changing an external magnetic field, the thin-film robot can achieve precise droplet capture and sub-droplet separation. The robot achieves precise droplet capture by adjusting the magnetic field strength, while in droplet separation, it uses micro / nano structure design and a periodic magnetic field to guide the droplets, achieving precise separation and rotation.

[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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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, The device includes a connecting plate, on both sides of which are symmetrically arranged movable plates. The movable plates can move towards the top of the connecting plate from the end away from the connecting plate until they converge and adsorb onto the surface of the droplet. The lower surfaces of the connecting plate and the movable plates are superhydrophobic surfaces with an array of micro-nano protrusions resembling lotus leaf surfaces. The droplet is in a Cassie state on the superhydrophobic surface. The upper surfaces of the connecting plate and the movable plates are subhydrophobic surfaces. Both the connecting plate and the movable plate contain magnetic particles.

2. The droplet transport magnetically controlled thin-film robot according to claim 1, characterized in that, The connection between the connecting plate and the movable plate is rounded.

3. The droplet transport magnetically controlled thin-film robot according to claim 1, characterized in that, The aspect ratio of the connecting plate and the movable plate is 1:

1.

4. The droplet transport 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. A method for preparing a droplet transport magnetically controlled thin-film robot according to any one of claims 1-4, characterized in that, The following steps are involved: S1. Place lotus leaf slices on the substrate material, cover with silicone rubber, press down and cure to capture the superhydrophobic microstructure features of the lotus leaf surface, and obtain a silicone rubber mold after demolding. S2. The rubber liquid and magnetic particles are thoroughly mixed and uniformly, and then degassed to obtain the magnetized rubber liquid. S3. Pour the magnetized rubber liquid into the silicone rubber mold obtained in step S1, and heat and solidify it to obtain a thin film sheet; S4. The thin film is laser-cut according to the set shape to obtain an integrated robot model; S5. Magnetize the robot model using a magnetizer. After uniform magnetization, a droplet transport magnetically controlled thin-film robot is obtained.

6. The method for preparing the droplet transport magnetically controlled thin-film robot according to claim 5, characterized in that, In step S2, the rubber liquid is polydimethylsiloxane, and the magnetic particles are neodymium iron boron.

7. The method for preparing the droplet transport magnetically controlled thin-film robot according to claim 5, characterized in that, In step S2, the mass ratio between the rubber liquid and the magnetic particles is 1:(1.4-1.6).

8. The method for preparing the droplet transport magnetically controlled thin-film robot according to claim 5, characterized in that, The magnetization direction in step S5 is parallel to the connecting edge of the connecting plate and the movable plate.

9. An application of a droplet transport magnetically controlled thin-film robot according to any one of claims 1-4 in the fields of droplet capture, rotation, and sub-droplet release.

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