A microfluidic chip and system for dilution refrigeration based on microdroplets

Abstract

The present invention belongs to the field of microfluidic chips and provides a microfluidic chip and system for dilution refrigeration based on microdroplets. The microfluidic chip for dilution refrigeration based on microdroplets includes a substrate, a main channel, a secondary channel, a droplet generating structure, and a droplet two-phase flow channel; the main channel, secondary channel, droplet generating structure, and droplet two-phase flow channel are arranged inside the substrate; one end of the main channel is connected to the main channel inlet, and the other end is connected to the first input end of the droplet generating structure; one end of the secondary channel is connected to the secondary channel inlet, and the other end is connected to the second input end of the droplet generating structure; and the output end of the droplet generating structure is connected to the droplet two-phase flow channel. The microfluidic chip for dilution refrigeration based on microdroplets has a simple structure, occupies a small space, and has more flexible usage scenarios.

Description

Technical Field

[0001] The present invention belongs to the field of microfluidic chips, and in particular relates to a microfluidic chip and system for dilution and refrigeration based on microdroplets. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In fields such as condensed matter physics, astronomical observations, quantum computing, superconductors, and superfluids, many research and applications require extremely low temperatures of several millikelvin. These extremely low operating temperatures are difficult to achieve using conventional refrigeration methods, such as air cooling and liquid cooling. Currently, the main methods for achieving extremely low temperatures include adsorption refrigeration, adiabatic demagnetization refrigeration, and dilution refrigeration. Dilution refrigeration is the most mature and has been widely used in fields such as quantum computing. Its core principle is that when a concentrated He-3 phase comes into contact with a diluted He-3 phase, the He-3 in the concentrated phase enters the dilute phase and absorbs heat, further providing cooling at extremely low temperatures. Therefore, this process is called "dilution refrigeration." Current dilution refrigeration technologies and equipment generally suffer from complex and bulky structures, poor flexibility, poor safety and stability, low refrigeration efficiency, and high helium consumption, which hinder the development of related research and applications. Summary of the Invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a microfluidic chip and system for dilution refrigeration based on microdroplets, which has a simple structure, occupies a small space, and has more flexible usage scenarios.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A microfluidic chip for dilution refrigeration based on microdroplets, comprising:

[0007] substrate, main flow channel, secondary flow channel, droplet generation structure and droplet two-phase flow channel;

[0008] The main flow channel, the secondary flow channel, the droplet generating structure and the droplet two-phase flow channel are arranged inside the substrate;

[0009] One end of the main channel is connected to the main channel inlet, and the other end is connected to the first input end of the droplet generating structure; one end of the secondary channel is connected to the secondary channel inlet, and the other end is connected to the second input end of the droplet generating structure; the output end of the droplet generating structure is connected to the droplet two-phase flow channel;

[0010] One of the main channel inlet and the secondary channel inlet is fed into the He-3 concentrated phase, and the other is fed into the He-3 diluted phase; the droplet generating structure is used to generate He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets; in the droplet two-phase flow channel, mass transfer occurs between the He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets and the He-3 diluted phase / He-3 concentrated phase.

[0011] As an embodiment, the outlet of the droplet two-phase flow channel is connected to a separator of a He-3 concentrated phase and a He-3 diluted phase.

[0012] As an embodiment, the droplet generating structure is a T-junction structure.

[0013] As an embodiment, the droplet generating structure is a flow focusing structure.

[0014] As an embodiment, when the main channel inlet is closed, the main channel and the droplet two-phase flow channel are filled with He-3 concentrated phase, and the length direction of the main channel is perpendicular to the horizontal plane, so that the He-3 dilute phase in the secondary flow channel forms droplets at the droplet generating structure under the action of gravity and flow heat and mass transfer occurs in the droplet two-phase flow channel.

[0015] As an embodiment, the paths and distribution of the droplet two-phase flow channels are arranged in the substrate according to the cooling capacity requirements and the cooling power distribution requirements.

[0016] As an embodiment, the droplet two-phase flow channels are evenly arranged in the substrate to achieve uniform cooling.

[0017] As an embodiment, the droplet two-phase flow channels are concentratedly distributed on both sides of the substrate to concentrate cooling on the positions on both sides.

[0018] As an embodiment, the connected main flow channel, secondary flow channel, droplet generating structure and droplet two-phase flow channel are regarded as a group of fluid passages; at least two groups of completely independent fluid passages are provided in the substrate.

[0019] A second aspect of the present invention provides a microfluidic system for dilution refrigeration based on microdroplets.

[0020] A microfluidic system for dilution refrigeration based on microdroplets, comprising:

[0021] A microfluidic chip for dilution refrigeration based on microdroplets as described above;

[0022] The outlet of the droplet two-phase flow channel in the microfluidic chip for dilution refrigeration based on microdroplets is connected to a phase separator via an outlet pipe;

[0023] A low-temperature bath is provided around the phase separator, and under the action of the low temperature, the He-3 concentrated phase and the He-3 diluted phase in the phase separator are separated;

[0024] The phase separator is further connected to either the main flow channel inlet or the secondary flow channel inlet via a dilute phase reflux pipe and a concentrated phase reflux pipe respectively;

[0025] The dilute phase reflux pipe and the concentrated phase reflux pipe are respectively provided with a dilute phase driving pump and a concentrated phase driving pump to drive the He-3 corresponding phase to flow.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention realizes dilution refrigeration by using a microfluidic chip, which greatly reduces the structural complexity of the dilution refrigeration equipment, making the entire microfluidic chip for dilution refrigeration based on microdroplets simple in structure, small in space, and more flexible in usage scenarios;

[0028] (2) The micro-droplet flow pattern of the present invention can enhance the heat and mass transfer between the He-3 concentrated phase and the He-3 diluted phase, thereby improving the refrigeration efficiency. It also utilizes the efficient heat and mass transfer characteristics between microfluids, which can indirectly reduce the amount of helium used, thereby reducing costs and the risk of helium leakage.

[0029] (3) The present invention has a high degree of integration and can integrate multiple droplet two-phase channels on a single microfluidic chip to further improve the refrigeration efficiency. The present invention can utilize designed micro-nano structures such as microchannels to control the flow of helium therein, thereby achieving functions such as flexible control of refrigeration capacity and control of refrigeration power distribution.

[0030] (4) Compared with the cylindrical structure of the mixing chamber in the existing dilution refrigerator, the thin-plate structure of the dilution refrigeration microfluidic chip of the present invention is more compact and easier to fit with the application end components; the thin-plate structure of the dilution refrigeration microfluidic chip of the present invention makes the interface between the He-3 concentrated phase and the He-3 dilute phase micro-elementary and diversified, and makes it closer to the application end components in space, which is more effective in cooling transfer.

[0031] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1This is a basic structural diagram of a microfluidic chip based on micro-droplets for dilution and refrigeration according to an embodiment of the present invention;

[0034] Figure 2 It is a T-junction droplet generating structure according to an embodiment of the present invention;

[0035] Figure 3 It is a fluid focusing droplet generating structure according to an embodiment of the present invention;

[0036] Figure 4 This is the flow situation near the micro-droplet of the embodiment of the present invention;

[0037] FIG5( a ) is a dilution refrigeration microfluidic chip with a complex droplet two-phase flow channel according to an embodiment of the present invention;

[0038] FIG5( b ) is another dilution refrigeration microfluidic chip with a complex droplet two-phase flow channel according to an embodiment of the present invention;

[0039] Figure 6 The present invention provides a dilution refrigeration microfluidic chip having a plurality of staggered flow channels;

[0040] Figure 7 This is a structural diagram of a microfluidic system for dilution refrigeration based on microdroplets according to an embodiment of the present invention.

[0041] Wherein: 1 substrate, 2 main channel inlet, 3 main channel, 4 secondary channel inlet, 5 secondary channel, 6 droplet generation structure, 7 droplet two-phase flow channel, 8 droplet two-phase flow channel outlet, 9 microfluidic chip, 10 outlet pipe, 11 phase separator, 12 low temperature bath, 13 dilute phase reflux pipe, 14 dilute phase drive pump, 15 concentrated phase reflux pipe, 16 concentrated phase drive pump, 17 dilute phase diversion manifold, 18 concentrated phase diversion manifold, 19 outlet collecting manifold. DETAILED DESCRIPTION

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0044] 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 invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] like Figure 1 As shown, a micro-droplet-based dilution refrigeration microfluidic chip structure includes: a substrate 1, a main channel inlet 2, a main channel 3, a secondary channel inlet 4, a secondary channel 5, a droplet generating structure 6, a droplet two-phase flow channel 7 and a droplet two-phase flow channel outlet 8.

[0046] It should be noted here that the geometric shape of the substrate 1 of the micro-droplet-based dilution refrigeration microfluidic chip is not limited and can be a thin rectangular parallelepiped, a thin cylinder, etc. The material used for its production must be resistant to extremely low temperatures and have good thermal conductivity, such as silver, copper, etc.

[0047] The flow cross-sections of the main flow channel 3 , the secondary flow channel 5 and the droplet two-phase flow channel 7 may be circular, rectangular or the like, and their sizes are not limited.

[0048] In some optional embodiments, micro sensors or micro valves may be installed on the main flow channel 3 , the secondary flow channel 5 and the droplet two-phase flow channel 7 to monitor and further control the flow rate, pressure, temperature, etc. therein.

[0049] Among them, the main channel 3, the secondary channel 5, the droplet generating structure 6 and the droplet two-phase flow channel 7 are arranged inside the substrate; one end of the main channel 3 is connected to the main channel inlet 2, and the other end is connected to the first input end of the droplet generating structure 6; one end of the secondary channel 5 is connected to the secondary channel inlet 4, and the other end is connected to the second input end of the droplet generating structure 6; the output end of the droplet generating structure 6 is connected to the droplet two-phase flow channel 7;

[0050] One of the main channel inlet 2 and the secondary channel inlet 4 is fed into the He-3 concentrated phase, and the other is fed into the He-3 diluted phase; the droplet generating structure 6 is used to generate He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets; in the droplet two-phase flow channel 7, mass transfer occurs between the He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets and the He-3 diluted phase / He-3 concentrated phase.

[0051] In this embodiment, the droplet generating structure 6 is used to generate He-3 concentrated phase droplets or He-3 diluted phase droplets, which depends on the type of fluid in the main channel 3, the secondary channel 5 and the specific structure type of the droplet generating structure 6.

[0052] It should be noted that the droplet generating structure 6 can be as follows Figure 1 Shown and Figure 2 The T-junction structure shown can also be Figure 3 The flow focusing structure shown is or other type of structure that can generate droplets.

[0053] The droplet two-phase flow channel 7 is used for the flow, heat transfer and mass transfer of the droplet and the fluid surrounding the droplet. Figure 4As shown, multiple reverse vortices are generated around the microdroplets, which greatly enhances the heat and mass transfer between the microdroplets and the surrounding fluid (between the He-3 concentrated phase and the He-3 diluted phase), thereby improving the efficiency of dilution refrigeration.

[0054] The paths and distribution of the droplet two-phase flow channels 7 are not restricted and can be arranged on the microfluidic chip according to the requirements of cooling capacity and cooling power distribution.

[0055] As shown in Figure 5(a), the droplet two-phase flow channels 7 are evenly distributed on the microfluidic chip, enabling uniform cooling. As shown in Figure 5(b), the droplet two-phase flow channels 7 are concentrated on both sides of the microfluidic chip, enabling concentrated cooling of the two sides while reducing cooling of the center.

[0056] like Figure 6 As shown, on the same microfluidic chip 9, the connected main channel 3, secondary channel 5, droplet generating structure 6 and droplet two-phase flow channel 7 are regarded as a group of fluid paths; at least two groups of completely independent fluid paths are set in the substrate 1. Among them, on the same microfluidic chip, multiple groups of fluid paths can be integrated by staggering the spatial distribution of each flow path. Figure 1 The fluid passages in the cooling system (different groups of fluid passages are completely independent and not interconnected) further increase the cooling capacity per unit space.

[0057] It can be understood here that the microfluidic chip based on the dilution refrigeration principle can be manufactured by integral cutting and punching, or by layered cutting, etching, punching and integrating into one, or can be manufactured using 3D printing technology.

[0058] The working principle of the micro-droplet-based dilution refrigeration microfluidic chip of the present invention is:

[0059] First, the He-3 concentrated phase and He-3 diluted phase flow through the main channel inlet 2, the secondary channel inlet 4 (or secondary channel inlet 4, main channel inlet 2), and the main channel 3, the secondary channel 5 (or secondary channel 5, main channel 3), respectively, to reach the droplet generation structure 6, where He-3 concentrated phase microdroplets or He-3 diluted phase microdroplets are generated. The microdroplets then enter the droplet two-phase flow channel 7, where mass transfer occurs between the microdroplets and another phase outside the microdroplets (diluting the He-3).

[0060] In particular, the main channel inlet 2 can be closed. At this time, the main channel 3 and the droplet two-phase flow channel 7 should be filled with He-3 concentrated phase, and the length direction of the main channel 3 should be perpendicular to the horizontal plane, so that the He-3 dilute phase in the 5 secondary flow channels can form droplets at the droplet generating structure 6 under the action of gravity and undergo flow heat and mass transfer (dilution of He-3) in the droplet two-phase flow channel 7.

[0061] The heat transfer and mass transfer process in the droplet two-phase flow channel 7 absorbs heat to achieve a cooling effect. Finally, the micro-droplets and the other phase outside the micro-droplets flow out of the droplet two-phase flow channel outlet 8 and enter the two-phase separator.

[0062] The microdroplet-based dilution refrigeration microfluidic chip of this embodiment is used in the fields of condensed matter physics, astronomical observation, quantum computing, superconductors, superfluids, etc.

[0063] In one or more embodiments, a microfluidic system for dilution refrigeration based on microdroplets includes:

[0064] As mentioned above, the microfluidic chip 9 for dilution refrigeration based on microdroplets; the droplet two-phase flow channel outlet 8 in the microfluidic chip 9 for dilution refrigeration based on microdroplets is connected to the phase separator 11 through the outlet pipe 10; a low-temperature bath 12 is arranged around the phase separator 11, and under the action of low temperature, the He-3 concentrated phase and the He-3 diluted phase in the phase separator 11 are separated; the phase separator 11 is also connected to any one of the main channel inlet 2 and the secondary channel inlet 4 through the dilution phase reflux pipe 13 and the concentrated phase reflux pipe 15 respectively; the dilution phase reflux pipe 13 and the concentrated phase reflux pipe 15 are respectively provided with a dilution phase drive pump 16 and a concentrated phase drive pump 18 to drive the corresponding He-3 phase to flow.

[0065] according to Figure 7 The main structure of the microfluidic system for dilution refrigeration based on microdroplets includes: a microfluidic chip 9, an outlet pipe 10, a phase separator 11, a low-temperature bath 12, a dilute phase reflux pipe 13, a dilute phase drive pump 14, a concentrated phase reflux pipe 15, a concentrated phase drive pump 16, a dilute phase diversion manifold 17, a concentrated phase diversion manifold 18 and an outlet collecting manifold 19. The microfluidic chip 9 in the microfluidic system for dilution refrigeration based on microdroplets is the above-mentioned microfluidic chip for dilution refrigeration based on microdroplets; one end of the outlet pipe 10 is connected to the outlet of the droplet two-phase flow channel 8, and the other end is connected to the phase separator 11; a low-temperature bath 12 is arranged around the phase separator 11. Under the action of low temperature, the He-3 concentrated phase and the He-3 diluted phase in the phase separator 11 are separated, and the He-3 concentrated phase floats on the upper part due to its lower density, and the He-3 diluted phase sinks to the lower part due to its higher density; one end of the dilution phase reflux pipe 13 is connected to the phase separator 11, and the other end is connected to the microfluidic chip 9. A dilution phase drive pump 14 is provided on the dilution phase reflux pipe 13 to drive the flow of the He-3 diluted phase; one end of the concentrated phase reflux pipe 15 is connected to the phase separator 11, and the other end is connected to the microfluidic chip 9. A concentrated phase drive pump 16 is provided on the concentrated phase reflux pipe 15 to drive the flow of the He-3 concentrated phase. The dilute phase reflux pipe 13, the concentrated phase reflux pipe 15, the outlet pipe 10 and the connection end of the microfluidic chip 9 can be respectively provided with a dilute phase diversion manifold 17, a concentrated phase diversion manifold 18 and an outlet collecting manifold 19 to match Figure 6The multi-channel design described in further increases the cooling capacity per unit space.

[0066] The flow heat and mass transfer process in the above-mentioned droplet two-phase flow channel 7 of the present embodiment absorbs heat and realizes the effect of refrigeration. Subsequently, the other phase outside the micro-droplet and the micro-droplet flows out from the droplet two-phase flow channel outlet 8 and enters the phase separator 11 through the outlet pipe 10. After the refrigeration of the low-temperature bath 12, the phase separation of the He-3 dilute phase and the He-3 concentrated phase occurs in the phase separator 11. The He-3 dilute phase and the He-3 concentrated phase flow back to the microfluidic chip 9 through the concentrated phase driven pump 16 and the concentrated phase reflux pipe 15 under the driving of the dilute phase driven pump 14 and the concentrated phase driven pump 16 respectively, forming a circulation loop and realizing continuous refrigeration.

[0067] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A microfluidic chip for dilution refrigeration based on microdroplets, characterized in that: include: substrate, main flow channel, secondary flow channel, droplet generation structure and droplet two-phase flow channel; The main flow channel, the secondary flow channel, the droplet generating structure and the droplet two-phase flow channel are arranged inside the substrate; One end of the main channel is connected to the main channel inlet, and the other end is connected to the first input end of the droplet generating structure; one end of the secondary channel is connected to the secondary channel inlet, and the other end is connected to the second input end of the droplet generating structure; the output end of the droplet generating structure is connected to the droplet two-phase flow channel; One of the main channel inlet and the secondary channel inlet is fed into the He-3 concentrated phase, and the other is fed into the He-3 diluted phase; the droplet generating structure is used to generate He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets; in the droplet two-phase flow channel, mass transfer occurs between the He-3 concentrated phase microdroplets / He-3 diluted phase microdroplets and the He-3 diluted phase / He-3 concentrated phase.

2. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: The outlet of the droplet two-phase flow channel is connected to a separator of a He-3 concentrated phase and a He-3 diluted phase.

3. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: The droplet generating structure is a T-junction structure.

4. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: The droplet generating structure is a flow focusing structure.

5. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: When the main channel inlet is closed, the main channel and the droplet two-phase flow channel are filled with He-3 concentrated phase, and the length direction of the main channel is perpendicular to the horizontal plane, so that the He-3 dilute phase in the secondary flow channel forms droplets at the droplet generating structure under the action of gravity and flow heat and mass transfer occurs in the droplet two-phase flow channel.

6. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: The paths and distribution of the droplet two-phase flow channels are arranged in the substrate according to the cooling capacity requirements and the cooling power distribution requirements.

7. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1 or 6, characterized in that: The droplet two-phase flow channels are evenly arranged in the substrate to achieve uniform cooling.

8. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1 or 6, characterized in that: The droplet two-phase flow channels are concentratedly distributed on both sides of the substrate to concentrate cooling on the positions on both sides.

9. The microfluidic chip for dilution refrigeration based on microdroplets according to claim 1, characterized in that: The mutual main flow channel, the secondary flow channel, the droplet generating structure and the droplet two-phase flow channel are regarded as a group of fluid passages; at least two groups of completely independent fluid passages are arranged in the substrate.

10. A microfluidic system for dilution refrigeration based on microdroplets, characterized in that: include: The microfluidic chip for dilution refrigeration based on microdroplets according to any one of claims 1 to 9; The outlet of the droplet two-phase flow channel in the microfluidic chip for dilution refrigeration based on microdroplets is connected to a phase separator via an outlet pipe; A low-temperature bath is provided around the phase separator, and under the action of the low temperature, the He-3 concentrated phase and the He-3 diluted phase in the phase separator are separated; The phase separator is further connected to either the main flow channel inlet or the secondary flow channel inlet via a dilute phase reflux pipe and a concentrated phase reflux pipe respectively; The dilute phase reflux pipe and the concentrated phase reflux pipe are respectively provided with a dilute phase driving pump and a concentrated phase driving pump to drive the He-3 corresponding phase to flow.

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