Low-temperature thermally-induced driving micropump containing magnetic phase-change material

Abstract

The invention discloses a low-temperature thermally-induced driving micropump containing a magnetic phase-change material, which comprises a pump body, and the pump body comprises a first end and a second end; the first end comprises an inlet pipe, an inlet reducing pipe, a pump cavity, an outlet reducing pipe and an outlet pipe which are used for pumping fluid and are sequentially communicated, and the contact area of the inlet reducing pipe and the pump cavity is larger than that of the outlet reducing pipe and the pump cavity; the second end comprises a miniature electromagnetic heater, a heat dissipation piston and a magnetic phase change material, the magnetic phase change material is located in a cavity formed by the heat dissipation piston and the miniature electromagnetic heater, and the heat dissipation piston is arranged below the pump cavity and used for transferring heat of the magnetic phase change material heated by the miniature electromagnetic heater to the pumped fluid. Pumping is achieved through gas-liquid phase change of the magnetic phase change material, the efficiency is high, the magnetic phase change material and pumped fluid are separated through the heat dissipation piston, the fluid is pumped without phase change, the pumping stability is guaranteed, and the whole structure is simple and can be integrated.

Description

Technical Field

[0001] The invention relates to the field of micro pumps, and in particular to a low-temperature thermally driven micro pump containing a magnetic phase change material. Background Art

[0002] Microfluidic systems play an important role in life sciences, biomedicine, aerospace and other disciplines. For example, microfluidic chemical analysis systems, artificial blood pumps for the treatment of myocardial infarction, microdrug injection systems and microfuel supplies for spacecraft all demonstrate high precision, high pumping stability and high degree of integration.

[0003] Micropumps are the actuators of microfluidic systems. They are responsible for the precise transmission and rapid control of trace fluids and are known as the "heart" of microfluidic systems. At present, the transmission methods of micropumps include mechanical and non-mechanical methods. Mechanical methods include piezoelectric, electrostatic, electromagnetic, and pneumatic. Non-mechanical methods include electroosmotic, thermally driven, and magnetofluidic. Among these mechanical and non-mechanical micropump driving methods, thermally driven pumps have the advantages of simple and compact structure, precise flow control, high pumping reliability, and high degree of integration. They have gradually become the mainstream direction of micropump development. However, there are some problems with current thermally driven pumps:

[0004] Pumping needs to rely on the phase change properties of the pumped material itself, that is, materials that do not undergo phase change at the working temperature cannot be pumped. Increasing the heater power can solve the problem of not being able to pump some fluid materials, but the higher temperature generated will cause the pump body to melt and the temperature of the pumped fluid will also increase, which does not meet the subsequent use requirements; and the bubble volume generated by the magnetic phase change material is limited, and the pumping efficiency is relatively low. Summary of the invention

[0005] In order to overcome the above technical problems, the present invention provides a low-temperature thermally driven micro pump containing a magnetic phase change material.

[0006] Specifically, the technical solution of the present invention is:

[0007] A low-temperature thermally driven micro pump containing a magnetic phase change material, comprising a pump body (1), wherein the pump body (1) is T-shaped and comprises an upper horizontal first end and a lower vertical second end;

[0008] The first end comprises an inlet pipe (101), an inlet reducer (102), a pump chamber (103), an outlet reducer (104), and an outlet pipe (105) which are used to pump fluid and are connected in sequence, and a contact area between the inlet reducer (102) and the pump chamber (103) is greater than a contact area between the outlet reducer (104) and the pump chamber (103);

[0009] The second end comprises a micro electromagnetic heater (2), a heat dissipation piston (3) and a magnetic phase change material (4); the magnetic phase change material (4) is located in a cavity formed by the heat dissipation piston (3) and the micro electromagnetic heater (2); the heat dissipation piston (3) is arranged below the pump cavity (103) and is used to transfer the heat of the magnetic phase change material (4) heated by the micro electromagnetic heater (2) to the pumped fluid.

[0010] According to a preferred embodiment, the micro electromagnetic heater (2) is connected to the coil (6) for switching on an interruptible current.

[0011] According to a preferred embodiment, the coil (6) is arranged at the second end and close to a side of the second end away from the first end.

[0012] According to a preferred embodiment, the magnetic phase change material (4) is obtained by uniformly mixing liquid paraffin and nano-scale iron powder coated with oleic acid.

[0013] According to a preferred embodiment, the vaporization temperature of the magnetic phase change material (4) is 30-38°C, and the volume of the vaporized magnetic phase change material (4) is the same as that of the magnetic phase change material (4) before vaporization.

[0014] According to a preferred embodiment, the second end further comprises a micro pressure sensor (5) for controlling the on and off of power to the coil (6) according to the detected pressure level.

[0015] According to a preferred embodiment, when the micro pressure sensor detects that the pressure is lower than a first threshold value M1, the coil (6) is controlled to be energized, and when the micro pressure sensor detects that the pressure is higher than a second threshold value M2, the coil (6) is controlled to be de-energized, wherein the first threshold value M1 is smaller than the second threshold value M2.

[0016] According to a preferred embodiment, the pump body (1) is made of polymethyl methacrylate.

[0017] According to a preferred embodiment, the heat dissipation piston (3) is cylindrical and has a gap with the interior of the pump body (1).

[0018] According to a preferred embodiment, a baffle (7) is provided in the pump chamber (103) to prevent the heat dissipation piston (3) from entering the pump chamber (103).

[0019] In the present invention, the magnetic phase change material (4) in the pump body expands under the heating of the micro electromagnetic heater (2), pushing the heat dissipation piston (3) to move to the bottom of the pump chamber. Since the contact area between the inlet tapered tube (102) and the pump chamber (103) is larger than the contact area between the outlet tapered tube (104) and the pump chamber (103), the pumped fluid will flow from a high pressure area with a large area to a low pressure area with a small area under the pressure difference between the two cross sections, thereby achieving a pumping effect. After the magnetic phase change material (4) becomes gas, it contacts the heat dissipation piston (3) and heat transfer occurs. The heat energy of the magnetic phase change material (4) is transferred to the pumped fluid through the heat dissipation piston (3), and the internal energy of the magnetic phase change material (4) decreases, returning to a liquid state and returning to the micro electromagnetic heater (2). During the entire working process, the volume change caused by the gas-liquid phase change of the magnetic phase change material (4) is used to realize the execution and circulation of pumping, and the pumping efficiency is relatively high. The magnetic phase change material (4) and the pumped fluid are separated by a heat dissipation piston (3) with good heat dissipation performance, and the pumped fluid is pumped without undergoing a phase change. There is no need to increase the heater power, and the pumping stability is further guaranteed. The overall structure is simple and can be integrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a low-temperature thermally driven micro pump containing a magnetic phase change material according to the present invention;

[0021] Figure 2 yes Figure 1 Schematic diagram of magnetic phase change material in;

[0022] Figure 3 yes Figure 1 Schematic diagram of the heat dissipation piston in .

[0023] Explanation of the reference numerals in the accompanying drawings: 1. Pump body; 2. Micro electromagnetic heater; 3. Heat dissipation piston; 4. Magnetic phase change material; 5. Micro pressure sensor; 6. Coil; 7. Baffle; 101. Inlet pipe; 102. Inlet tapered pipe; 103. Pump chamber; 104. Outlet tapered pipe; 105. Outlet pipe. DETAILED DESCRIPTION

[0024] Microfluidic systems play an important role in life sciences, biomedicine, aerospace and other disciplines. For example, microfluidic chemical analysis systems, artificial blood pumps for the treatment of myocardial infarction, microdrug injection systems and microfuel supplies for spacecraft all demonstrate high precision, high pumping stability and high degree of integration.

[0025] Micropumps are the actuators of microfluidic systems. They are responsible for the precise transmission and rapid control of trace fluids and are known as the "heart" of microfluidic systems. At present, the transmission methods of micropumps include mechanical and non-mechanical methods. Mechanical methods include piezoelectric, electrostatic, electromagnetic, and pneumatic. Non-mechanical methods include electroosmotic, thermally driven, and magnetofluidic. Among these mechanical and non-mechanical micropump driving methods, thermally driven pumps have the advantages of simple and compact structure, precise flow control, high pumping reliability, and high degree of integration. They have gradually become the mainstream direction of micropump development. However, there are some problems with current thermally driven pumps:

[0026] Pumping needs to rely on the phase change properties of the pumped material itself, that is, materials that do not undergo phase change at the working temperature cannot be pumped. Increasing the heater power can solve the problem of not being able to pump some fluid materials, but the higher temperature generated will cause the pump body to melt and the temperature of the pumped fluid will also increase, which does not meet the subsequent use requirements; and the bubble volume generated by the magnetic phase change material is limited, and the pumping efficiency is relatively low.

[0027] In order to overcome the above technical problems, the present invention provides a low-temperature thermally driven micro pump containing a magnetic phase change material.

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] For details, see Figure 1 , a specific embodiment of the present invention is:

[0030] A low-temperature thermally driven micro pump containing a magnetic phase change material, comprising a pump body 1, wherein the pump body 1 is T-shaped, comprising an upper horizontal first end and a lower vertical second end;

[0031] The first end includes an inlet pipe 101, an inlet reducer 102, a pump chamber 103, an outlet reducer 104, and an outlet pipe 105, which are used to pump fluid and are connected in sequence, and the contact area between the inlet reducer 102 and the pump chamber 103 is greater than the contact area between the outlet reducer 104 and the pump chamber 103;

[0032] The second end includes a micro electromagnetic heater 2, a heat dissipation piston 3 and a magnetic phase change material 4. The magnetic phase change material 4 is located in a cavity formed by the heat dissipation piston 3 and the micro electromagnetic heater 2. The heat dissipation piston 3 is arranged below the pump chamber 103 and is used to transfer the heat of the magnetic phase change material 4 heated by the micro electromagnetic heater 2 to the pumped fluid.

[0033] In the present invention, the magnetic phase change material 4 in the pump body 1 expands under the heating of the micro electromagnetic heater 2, pushing the heat dissipation piston 3 to move to the bottom of the pump chamber 103. Since the contact area between the inlet reducer 102 and the pump chamber 103 is larger than the contact area between the outlet reducer 104 and the pump chamber 103, the pumped fluid will flow from the high pressure area with a large area to the low pressure area with a small area under the pressure difference between the two cross sections, that is, it flows from the inlet pipe 101 through the inlet reducer 102, the pump chamber 103, and the outlet reducer 104 in sequence, and finally stays in the outlet pipe 105, so as to achieve the pumping effect. After the magnetic phase change material 4 becomes gas, it contacts with the heat dissipation piston 3 and heat transfer occurs. The heat energy of the magnetic phase change material 4 is transferred to the pumped fluid through the heat dissipation piston 3, and the internal energy of the magnetic phase change material 4 decreases, recovers to a liquid state, and returns to the micro electromagnetic heater 2. During the entire working process, the volume change caused by the gas-liquid phase change of the magnetic phase change material 4 is used to realize the execution and circulation of pumping, and the pumping efficiency is high. The magnetic phase change material 4 and the pumped fluid are separated by the heat dissipation piston 3 with good heat dissipation. The pumped fluid is pumped without phase change, and there is no need to increase the heater power, which further ensures the pumping stability. The overall structure is simple and can be integrated. Fluids at room temperature of about 20°C and below can be pumped, and do not rely on their own phase change properties.

[0034] refer to Figure 1 , a selection of inlet reducer 102, pump chamber 103, outlet reducer 104 and outlet pipe 105 is given, wherein inlet pipe 101 and outlet pipe 105 can be selected as general type test tubes, inlet reducer 102 and outlet reducer 104 can be selected as conical test tubes, and pump chamber 103 can be selected as spherical pump chamber 103. The inlet reducer 102 is connected to the pump chamber 103 with its larger end face, and the outlet reducer 104 is connected to the pump chamber 103 with its smaller end face. According to Bernoulli's principle, the pumped fluid can flow from a high pressure area with a large area to a low pressure area with a small area.

[0035] According to a preferred embodiment, the micro electromagnetic heater 2 is connected to the coil 6 for connecting an interruptible current. The micro electromagnetic heater 2 is connected to an interruptible current, and when the magnetic phase change material 4 is in a liquid state, it starts to heat the liquid until it vaporizes. The magnetic phase change material 4 in the pump body 1 expands under the heating of the micro electromagnetic heater 2, pushing the heat dissipation piston 3 to move to the bottom of the pump chamber 103. At this time, the micro electromagnetic heater 2 is controlled to be powered off through the coil 6, and the next round of heating is started again after the continuous phase change material changes into a liquid again.

[0036] Furthermore, the coil 6 is disposed at the second end and is located on the side of the second end away from the first end. That is, the coil 6 is located at the bottom of the T-shaped pump body 1. This can avoid affecting the pumping process of the first end and is also conducive to integration.

[0037] According to a preferred embodiment, Figure 2 As shown, the magnetic phase change material 4 is obtained by uniformly mixing liquid paraffin and nano-scale iron powder coated with oleic acid on the surface. The magnetic phase change material 4 obtained in this way can be gasified at low temperature. According to experimental data, the gasification temperature is 30-38°C, and the volume of the gasified magnetic phase change material 4 is smaller than that of the magnetic phase change material 4 before gasification. In this way, the heat dissipation piston 3 is pushed to move to the bottom of the pump chamber 103. The magnetic phase change material 4 exchanges heat with the pumped fluid through the heat dissipation piston 3, thereby promoting the movement of the pumped fluid.

[0038] Furthermore, the magnetic phase change material 4 is evenly distributed in the cavity formed by the heat dissipation piston 3 and the micro electromagnetic heater 2 .

[0039] According to a preferred embodiment, the second end further includes a micro pressure sensor 5, which is used to control the on and off of the coil 6 according to the detected pressure level. When the magnetic phase change material 4 is in a liquid state, the pressure is small, and the coil 6 is controlled to be energized, so that the micro electromagnetic heater 2 starts to heat until the magnetic phase change material 4 is vaporized. After vaporization, the pressure in the pump chamber 103 increases, and the micro pressure sensor 5 detects a certain degree of change, and then controls the coil 6 to be powered off, and the micro electromagnetic heater 2 stops heating. In this way, an automatic cyclical workflow is achieved.

[0040] Furthermore, in the above, when the micro pressure sensor 5 detects that the pressure is lower than the first threshold value M1, the coil 6 is controlled to be energized, and when the micro pressure sensor 5 detects that the pressure is higher than the second threshold value M2, the coil 6 is controlled to be de-energized, wherein the first threshold value M1 is less than the second threshold value M2. The specific values ​​of M1 and M2 are set according to specific needs.

[0041] According to a preferred embodiment, the pump body 1 is made of polymethyl methacrylate, which has the characteristics of high transparency, good heat resistance, strong chemical resistance, good processability and excellent physical properties.

[0042] In other implementations, other materials meeting the above characteristics may also be selected. This application only provides a preferred embodiment and does not make an absolute limitation.

[0043] According to a preferred embodiment, the heat dissipation piston 3 is cylindrical, which fits the diameter of the second end of the pump body 1, and there is a certain gap, which is convenient for sliding under the driving action of the magnetic phase change material 4. However, this gap is small, and the magnetic phase change material 4 will not enter the pump cavity 103. At the same time, the heat dissipation piston 3 can be made of aluminum and aluminum alloy, and the outside is silver-plated. It has excellent thermal conductivity, improves pumping efficiency, and has both structural strength and certain slidability.

[0044] According to a preferred embodiment, a baffle 7 is provided in the pump chamber 103 to prevent the heat dissipation piston 3 from entering the pump chamber 103. Figure 1 and Figure 3 As shown, the heat dissipation piston 3 and the baffle 7 are matched in shape and are provided with an arc-shaped adaptation end to ensure the stability of the heat transfer process.

[0045] The above is a detailed introduction to a low-temperature thermally driven micropump containing a magnetic phase change material provided in an embodiment of the present invention. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0046] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0047] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

Claims

1. A low-temperature thermally driven micropump containing a magnetic phase change material, characterized in that: The pump body (1) is T-shaped and includes a first horizontal end at the top and a second vertical end at the bottom; The first end comprises an inlet pipe (101), an inlet reducer (102), a pump chamber (103), an outlet reducer (104), and an outlet pipe (105) which are used to pump fluid and are connected in sequence, and a contact area between the inlet reducer (102) and the pump chamber (103) is greater than a contact area between the outlet reducer (104) and the pump chamber (103); The second end comprises a micro electromagnetic heater (2), a heat dissipation piston (3) and a magnetic phase change material (4); the magnetic phase change material (4) is located in a cavity formed by the heat dissipation piston (3) and the micro electromagnetic heater (2); the heat dissipation piston (3) is arranged below the pump cavity (103) and is used to transfer the heat of the magnetic phase change material (4) heated by the micro electromagnetic heater (2) to the pumped fluid.

2. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 1, characterized in that: The micro electromagnetic heater (2) is connected to the coil (6) and is used to switch on an interruptible current.

3. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 2, characterized in that: The coil (6) is arranged at the second end and is close to a side of the second end away from the first end.

4. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 3, characterized in that: The magnetic phase change material (4) is obtained by uniformly mixing liquid paraffin and nanometer-scale iron powder with oleic acid coated on the surface.

5. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 4, characterized in that: The vaporization temperature of the magnetic phase change material (4) is 30-38° C., and the volume of the magnetic phase change material (4) after vaporization is the same as that of the magnetic phase change material (4) before vaporization.

6. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 5, characterized in that: The second end also includes a micro pressure sensor (5) for controlling the on and off of the coil (6) according to the detected pressure level.

7. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 6, characterized in that: When the micro pressure sensor detects that the pressure is lower than a first threshold value M1, the coil (6) is controlled to be powered on; when the micro pressure sensor detects that the pressure is higher than a second threshold value M2, the coil (6) is controlled to be powered off, wherein the first threshold value M1 is smaller than the second threshold value M2.

8. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 1, characterized in that: The pump body (1) is made of polymethyl methacrylate.

9. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 1, characterized in that: The heat dissipation piston (3) is cylindrical and has a gap with the inside of the pump body (1).

10. The low-temperature thermally driven micro pump containing magnetic phase change material according to claim 1, characterized in that: A baffle (7) is provided in the pump chamber (103) to prevent the heat dissipation piston (3) from entering the pump chamber (103).

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