Four-drive magnetic source ferrofluid micro-pump with embedded fixed magnetic source

Abstract

The application discloses a four-drive magnetic source ferromagnetic fluid micro-pump with embedded fixed magnetic sources, and belongs to the technical field of micro-fluid transmission control. The micro-pump comprises a pump body provided with a circular pump cavity, ferromagnetic fluid accommodated in the pump cavity, and a magnetic source system composed of a fixed magnetic source and four rotatable driving magnetic sources. Two driving magnetic sources are arranged on two sides of the pump cavity in each group, and can synchronously rotate around the axis of the pump cavity. The fixed magnetic source and the driving magnetic sources form a five-magnetic-source coupling structure, and a uniform and efficient superimposed magnetic field is generated in the circular pump cavity, so that the ferromagnetic fluid is magnetized to form a stable 'driving disc'. The driving disc rotates with the driving magnetic sources and periodically changes the volume of the pump cavity, so that the fluid is directionally pumped from the liquid inlet to the liquid outlet. Through the multi-magnetic-source coupling and rotary driving design, the magnetic field force and uniformity are significantly enhanced, the driving force, the back pressure resistance, the operation stability and the rotating speed of the micro-pump are effectively improved, and the pollution risk of the magnetic fluid is reduced.

Description

Technical Field

[0001] This application relates to the field of microfluidic transport control technology, and in particular to a four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source. Background Technology

[0002] In recent years, with the widespread application and rapid development of microfluidic technology in fields such as microelectromechanical systems, precision electronic equipment, biomedical engineering, aerospace, in vitro diagnostics, and forensic identification, the performance requirements of micropumps, as their core driving components, have also been increasing. Micropumps not only need to achieve precise driving and control of microfluidics in scenarios such as electronic system cooling, PCR amplification, spacecraft fuel precision supply, drug delivery, and micro total analysis systems, but also face the urgent need for highly integrated structures, intelligent and reliable operation, and simplified processes.

[0003] Currently, micropumps are mainly divided into two categories: mechanical and non-mechanical. Traditional mechanical micropumps are often limited in their development due to their complex structure, difficult manufacturing process, high power consumption, and limited reliability and integration. In contrast, non-mechanical micropumps have attracted widespread attention due to their advantages such as no moving parts, no mechanical fatigue, and high reliability. Among them, ferrofluidic micropumps, with their simple structure, ease of integration, flexible control, low driving voltage, and good self-sealing and low friction characteristics, have become one of the key research directions.

[0004] However, existing ferrofluidic micropumps still generally suffer from bottlenecks such as limited driving force, insufficient output flow and back pressure capacity, and low long-term operational stability, which restrict their further practical application. In the past fifty years, although researchers have gained a deep understanding of the magnetofluid drive principle and developed various pump structures based on advanced processing technologies, the core problem has not yet been fundamentally solved:

[0005] (1) The magnetic driving force is small: Due to the limitations of microscale space, only micro coils or small permanent magnets can be used to provide the magnetic field, resulting in limited magnetic field energy density and insufficient magnetic driving force acting on ferrofluids.

[0006] (2) Low back pressure resistance: Under high back pressure conditions, ferrofluids are prone to reverse flow or even rupture, causing their self-sealing function to fail and their pumping performance to drop significantly.

[0007] (3) Pumping speed is limited: Flow rate regulation mainly depends on increasing the speed. However, at high speeds, the fluid viscous resistance increases sharply. Once the resistance exceeds the magnetic drive force, the movement of the magnetohydrodynamic plug will lag, and the pumping efficiency will decrease rapidly.

[0008] (4) Risk of fluid contamination: During operation, the ferrofluid comes into direct contact with the transported medium, and the interface is prone to instability under the magnetic-fluid coupling effect. Especially under high-speed and high-pressure conditions, the ferrofluid may break, peel off, or disperse at the edges, producing micron-sized particles that remain, causing medium contamination. Long-term operation may also affect fluid purity due to material aging and surfactant leaching. This is particularly critical in sensitive fields such as biomedicine and the transport of high-purity chemicals. Therefore, improving the uniformity of the magnetic field distribution and the binding ability of the ferrofluid is an important way to suppress contamination.

[0009] In summary, improving the magnitude and uniformity of the force exerted by the magnetic field on the ferrofluid is key to enhancing its driving performance and sealing reliability. Based on this, this application proposes a four-drive magnetic source ferrofluid micropump with an embedded fixed magnetic source, starting from the flow and sealing mechanism of ferrofluids. Summary of the Invention

[0010] The technical problem addressed by this invention is to propose a four-drive magnetic source ferrofluid micropump with an embedded fixed magnetic source. By optimizing the pump cavity structure and the spatial layout of the magnetic source, the effective magnetization volume of the ferrofluid is increased, and the overall magnetization intensity and magnetic field uniformity are improved, thereby effectively strengthening the magnetic driving force and self-sealing capability, and providing an innovative solution to the above-mentioned bottleneck problem.

[0011] To solve the technical problem, the technical solution of the present invention is as follows:

[0012] A four-drive magnetic source ferrofluid micropump with an embedded fixed magnetic source includes: a micropump body with a circular pump cavity inside and an inlet channel and an outlet channel respectively communicating with the circular pump cavity; a ferrofluid contained in the circular pump cavity; a magnetic source system including a fixed magnetic source and multiple drive magnetic sources, the fixed magnetic source being embedded and fixed in the micropump body and its magnetic field acting on the circular pump cavity; the multiple drive magnetic sources being rotatably arranged around the circular pump cavity and their magnetic poles passing through the circular pump cavity; and a drive unit being drively connected to the drive magnetic sources for driving the drive magnetic sources to rotate synchronously around the axis of the circular pump cavity.

[0013] The fixed magnetic source and the plurality of driving magnetic sources constitute a multi-magnetic source coupling structure, forming a superimposed magnetic field in the circular pump cavity. Under the action of the magnetic field, the ferrofluid forms a driving structure that separates the inlet and outlet channels. When the driving magnetic source rotates, the driving structure moves synchronously and periodically changes the pump cavity volume, thereby realizing the pumping of fluid from the inlet channel to the outlet channel.

[0014] Furthermore, the number of driving magnetic sources is four, and the driving magnetic sources are arranged in pairs on both sides of the circular pump cavity, with the two driving magnetic sources in the same group being symmetrically arranged about the axis of the circular pump cavity.

[0015] Furthermore, the drive unit includes a motor and a turntable; the output shaft of the motor is drivenly connected to the turntable; and the drive magnetic source located on the same side of the circular pump cavity is fixedly installed on the same turntable.

[0016] Furthermore, the fixed magnetic source is a cylindrical permanent magnet with the magnetization direction along the axial direction; the side wall of the micropump body is provided with a through hole, and the fixed magnetic source is embedded and bonded to the through hole.

[0017] Furthermore, the widths of both the inlet channel and the outlet channel are smaller than the diameter of the circular pump chamber, and they are symmetrically arranged on opposite sides of the circular pump chamber.

[0018] Furthermore, the pump body of the micropump is made of a magnetically permeable non-magnetic material.

[0019] Furthermore, the magnetically permeable non-magnetic material is polymethyl methacrylate.

[0020] Furthermore, in each group of driving magnetic sources arranged on the same side of the circular pump cavity, the two driving magnetic sources are distributed in a 180° rotational symmetry with respect to the axis of the circular pump cavity.

[0021] Furthermore, the turntable is provided with a groove that matches the shape of the driving magnetic source, and the driving magnetic source is embedded in the groove.

[0022] This application has the following advantages:

[0023] Significantly enhances magnetic drive force: By forming a five-magnetic-source coupling structure with an embedded fixed magnetic source and four covered drive magnetic sources, the interaction distance between the magnetic source and the ferrofluid in the pump cavity is effectively shortened, forming a uniform and efficient superimposed magnetic field in the circular pump cavity, enabling the ferrofluid to obtain a stronger and more uniformly distributed magnetic field force, thereby greatly improving the magnetic drive force.

[0024] Effectively improves pressure resistance limit: Relying on a reasonable pump cavity structure and magnetic source arrangement, a strong and uniform coupled magnetic field is formed within the cavity. This magnetic field can attract more ferrofluid within the pump cavity and endow it with high and stable magnetization force, enabling it to resist greater reverse pressure differentials, thereby significantly improving the self-sealing performance and pressure resistance limit of the micropump.

[0025] Achieving higher pumping speeds: In microflow, viscous resistance dominates, and increasing the speed leads to a sharp increase in resistance. This application overcomes viscous resistance at high speeds by enhancing the magnetic field force to provide higher driving energy for the ferrofluid. Simultaneously, the circular pump chamber widens the fluid passage, which is more conducive to reducing flow resistance compared to a narrow tube, thus supporting stable pumping at higher speeds.

[0026] Enhanced operational stability and suppression of backflow: The four-drive magnetic source design with a centrally symmetrical layout ensures that the inlet and outlet of the micropump are always isolated throughout the entire pumping cycle of ferromagnetic fluid fusion and separation, fundamentally preventing liquid backflow on the outlet side and ensuring the continuity and stability of flow output.

[0027] Reduced risk of magnetofluid contamination: The uniform and strong magnetic field formed by the coupling of five magnetic sources enables the ferrofluid to form a rigid and stable disc-shaped drive blade within the pump chamber. This structure strengthens the magnetic confinement of the ferrofluid, and with the appropriate addition of ferrofluid, it can effectively suppress its breakage, dispersion, or escape due to interfacial instability or uneven magnetic field, thereby significantly reducing the risk of contamination to the transported liquid. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of the four-drive magnetic source ferrofluidic micropump with embedded fixed magnetic source provided in the embodiment;

[0030] Figure 2 A schematic diagram of the micropumping process provided in the embodiments;

[0031] Figure 3 3D structural diagram of the four-drive magnetic source ferrofluidic micropump with embedded fixed magnetic source provided in the embodiment.

[0032] Explanation of icon numbers:

[0033] 1-Liquid outlet channel; 2-Rotating magnetic source a; 3-Liquid inlet channel; 4-Ferromagnetic fluid; 5-Fixed magnetic source; 6-Rotating magnetic source b; 7-Micro pump body; 8-Circular turntable; 9-Motor. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Example 1:

[0036] like Figure 1-3As shown, this application embodiment provides a four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source. The system overview and composition include: liquid outlet channel 1, Rotating magnetic source a2 The system comprises: 3. Inlet channel; 4. Ferrofluid; 5. Fixed magnetic source; 6. Rotating magnetic source b; 7. Micropump body; 8. Circular turntable; and 9. Planetary geared stepper motor. The outlet channel 1 is the outlet for the pumped liquid; the rotating magnetic source a2 drives the ferrofluid; the inlet channel 3 is the inlet for the pumped liquid; and the ferrofluid 4 propels the pumped liquid within the pump chamber while simultaneously isolating it. Import and export channels Backflow is suppressed; a fixed magnetic source 5 provides a constant permanent magnetic field to fix the ferrofluid 4 and enhance its magnetization ability; a rotating magnetic source b drives the ferrofluid to move. The micropump body 7 is the main body of the micropump, the flow channel between the ferrofluid 4 and the pumped liquid, mainly playing a role in restricting and guiding the liquid flow. Because it needs to have the function of not blocking the transmission of magnetic field, and should have certain pressure resistance, light weight and other characteristics, polymethyl methacrylate material is generally selected; the circular turntable 8 is the connecting part between the rotating magnetic source and the motor shaft. The planetary geared stepper motor 9 is the power source that drives the ferrofluid during the pumping process of the ferrofluid micropump.

[0037] For example, the working principle of a four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source in this embodiment is as follows:

[0038] The planetary geared stepper motor 9's shaft is connected to the circular turntable 8 via a bayonet-embedded connection. The circular turntable 8 has a diameter of 20mm and two circular grooves with a depth of 1mm and a diameter of 5mm at a symmetrical position 6mm off-center. Rotating magnetic sources a2 and b6, each with a diameter of 5mm, are embedded in the circular grooves and fixed with adhesive. The magnetohydrodynamic micropump body 7 is manufactured using PDMS chip processing technology. A circular slot with a diameter of 8mm is provided at a position 4mm off-center from the micropump. The slot extends from the opening on the outer surface of the micropump to the other side, and the depth of the circular slot is equal to the thickness of the micropump cavity. The internal space of this slot is completely isolated from the internal space of the circular pump cavity. The fixed magnetic source 5 is embedded into the pump cavity through an external opening and fixed with adhesive. The inlet channel 3 and outlet channel 1 of the magnetohydrodynamic micropump are both 0.6mm wide, and the depth of both channels is the same as that of the pump cavity and is integral with the micropump.

[0039] The planetary geared stepper motor 9 is driven by a stepper motor driver and its speed, direction, and rotation amount can be controlled by a programmable logic controller. The circular turntable 8 and the shaft of the planetary geared stepper motor 9 are connected by a bayonet embedding and fixed with glue to ensure that the circular turntable 8 and the shaft of the planetary geared stepper motor 9 rotate synchronously. The rotating magnetic sources a2 and b6 are embedded in two symmetrical circular grooves of the circular turntable and fixed with glue. The four rotating magnetic sources are cylindrical permanent magnets with the magnetic poles along the axis of the cylinder. The magnetic fluid micropump 7 has a very small pump body size and is made using PDMS chip processing technology. Its material is PMMA (polymethyl methacrylate) with high transparency, which makes it easy to observe the internal operation of the pump chamber. The embedded fixed magnetic source 5 is embedded through the slot opening located outside the circular pump chamber and fixed with glue. The fixed magnetic source uses a cylindrical permanent magnet with the magnetic poles aligned along the axis of the cylinder. A relatively stable "magnetic fluid drive disk" (magnetic fluid 4) is formed within the magnetic field generated by the superposition of five magnetic sources: rotating magnetic source a2, rotating magnetic source b6, and embedded fixed magnetic source 5. This "magnetic fluid drive disk" exhibits a periodic shape change as the two rotating magnetic sources move, pushing the liquid while its volume continuously changes within the micropump cavity, thus achieving liquid pumping. The inlet channel 3 and outlet channel 1 are respectively located on symmetrical sides of the circular pump cavity and have very small widths, ensuring that the inlet and outlet are always isolated during the entire pumping process, thereby suppressing liquid backflow.

[0040] Throughout the pumping process of the micropump, the "magnetic fluid drive disk" formed within the pump chamber and the volume of the pump chamber exhibit periodic changes. Externally, rotating magnetic sources a2 and b6 move synchronously clockwise under the drive of the planetary reduction stepper motor 9. The liquid in the right pump chamber is propelled forward along the circular pump chamber by the "magnetic fluid drive disk" formed by the magnetic fluid 4; while the liquid in the left pump chamber is propelled by the "magnetic fluid drive disk" formed by the magnetic fluid 4, its volume is compressed, and the liquid is pumped out through the outlet channel 1. The inlet channel 3 and outlet channel 1 are respectively located on symmetrical sides of the circular pump chamber and have a very small width, ensuring that the inlet and outlet are always isolated throughout the pumping process, thereby suppressing liquid backflow.

[0041] It can be understood that this device employs a five-magnetic-source coupling structure consisting of an embedded fixed magnetic source and four covered drive magnetic sources. This creates a uniform and efficient superimposed magnetic field within the circular pump chamber, resulting in more complete magnetization of the ferrofluid and the formation of a highly rigid and stable disc-shaped drive blade. This blade rotates with the drive magnetic source, changing the pump chamber volume and propelling the liquid for continuous pumping. The magnetic source layout enhances the magnetization area and magnetic force, improving pumping capacity and sealing performance while suppressing backflow.

[0042] It can be understood that this device is based on the flow mechanism and sealing principle of ferrofluids, and proposes a ferrofluid micropump with a five-magnetic-source coupling layout, thereby achieving the purpose of improving the magnetic driving force, self-sealing pressure resistance and pumping stability of the ferrofluid micropump.

[0043] The magnetic force density experienced by this ferrofluid The pressure difference is Due to the coupling of the five magnetic sources, the generated magnetic fields superimpose, increasing the magnetic field strength H and the magnetic field strength gradient ∆H. This results in a greater magnetic force and driving pressure difference on the ferrofluid, thereby increasing the driving force of the ferrofluid. (µ0 is the vacuum permeability, M is the magnetization of the ferrohydrodynamic fluid, and H is the magnetic field strength).

[0044] It can be understood that the combination of embedded and covered magnetic source arrangement shortens the magnetic moment, enhances the magnetization effect and effective area of ​​the ferrofluid, and improves pumping stability.

[0045] It is understandable that, at the microscopic scale, viscous forces dominate fluid behavior. This application enables ferrofluids to overcome viscous resistance at high rotational speeds by enhancing the magnetic field force, and the circular pump chamber structure also helps to reduce flow resistance.

[0046] It is understood that this application reduces pollution by optimizing the magnetic field confinement and the amount of ferrofluid used, thereby suppressing magnetofluid splitting and escape.

[0047] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0048] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source, characterized in that, include: The micropump body (7) has a circular pump cavity inside and an inlet channel (3) and an outlet channel (1) respectively connected to the circular pump cavity; a ferromagnetic fluid (4) is contained in the circular pump cavity; a magnetic source system includes a fixed magnetic source (5) and multiple driving magnetic sources, the fixed magnetic source (5) is embedded and fixed in the micropump body (7) and the magnetic field acts on the circular pump cavity; the multiple driving magnetic sources are rotatably arranged around the circular pump cavity and the magnetic pole direction passes through the circular pump cavity; a driving unit is connected to the driving magnetic source and is used to drive the driving magnetic source to rotate synchronously around the axis of the circular pump cavity; The fixed magnetic source (5) and the multiple driving magnetic sources form a multi-magnetic source coupling structure, forming a superimposed magnetic field in the circular pump cavity. The ferromagnetic fluid (4) forms a driving structure that separates the inlet and outlet channels under the action of the magnetic field. When the driving magnetic source rotates, the driving structure moves synchronously and periodically changes the pump cavity volume, thereby realizing the pumping of fluid from the inlet channel (3) to the outlet channel (1).

2. The four-drive magnetic source ferrofluidic micropump with embedded fixed magnetic source according to claim 1, characterized in that, The number of driving magnetic sources is four. The driving magnetic sources are arranged in pairs on both sides of the circular pump cavity, and the two driving magnetic sources in the same group are symmetrical about the axis of the circular pump cavity.

3. The four-drive magnetic source ferrofluidic micropump with embedded fixed magnetic source according to claim 2, characterized in that, The drive unit includes a motor (9) and a turntable (8); the output shaft of the motor (9) is driven to the turntable (8); the drive magnetic source located on the same side of the circular pump cavity is fixedly installed on the same turntable (8).

4. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 1, characterized in that, The fixed magnetic source (5) is a cylindrical permanent magnet with the magnetization direction along the axial direction; the side wall of the micro pump body (7) is provided with a through hole, and the fixed magnetic source (5) is embedded and bonded to the through hole.

5. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 1, characterized in that, The width of the inlet channel (3) and the outlet channel (1) is smaller than the diameter of the circular pump chamber, and they are symmetrically arranged on opposite sides of the circular pump chamber.

6. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 1, characterized in that, The pump body (7) of the micropump is made of a magnetically permeable non-magnetic material.

7. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 6, characterized in that, The magnetically permeable non-magnetic material is polymethyl methacrylate.

8. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 2, characterized in that, In each set of driving magnetic sources arranged on the same side of the circular pump cavity, the two driving magnetic sources are distributed in a 180° rotational symmetry with respect to the axis of the circular pump cavity.

9. A four-drive magnetic source ferrofluidic micropump with an embedded fixed magnetic source according to claim 2, characterized in that, The turntable (8) is provided with a groove that matches the shape of the driving magnetic source, and the driving magnetic source is embedded in the groove.

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