Microfluidic device and system for determining and sorting thermophoresis parameters of particles

Abstract

The invention provides a microfluidic device and system for determining and sorting thermophoresis parameters of particles. The microfluidic device comprises a microchannel, a first heat exchange channel, a second heat exchange channel, a sample inlet and a sample outlet, the microchannel is arranged at the center of the microfluidic device; two ends of the micro-channel are respectively communicated with the sample inlet and the sample outlet; the first heat exchange channel and the second heat exchange channel are symmetrically arranged on the two sides of the micro-channel. And the flowing directions of heat exchange media in the first heat exchange channel and the second heat exchange channel are opposite. Through the design of the micro-channel and the two heat exchange channels, a stable and uniform temperature gradient can be established in the micro-channel, and meanwhile measurement of thermophoresis parameters of the particles and efficient sorting of different types of particles are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of particle thermophoresis parameter measurement and sorting, and relates to a microfluidic device and system for particle thermophoresis parameter measurement and sorting. Background Art

[0002] Microfluidic technology, as a cutting-edge technology widely used in the fields of biomedicine, chemical analysis, and materials science, has greatly promoted the development of these fields. Through the delicate design of microchannel structures, microfluidic chips achieve precise manipulation of tiny volumes of liquids, with advantages such as high throughput and high sensitivity, and have shown good performance in fluid mixing, reaction control, and sample processing.

[0003] In recent years, with the in-depth research and wide application of micro-nano particles in the directions of life science, environmental detection, and materials synthesis, how to efficiently and accurately sort different particles and understand their transport behaviors under external fields has become an important research topic. Among them, thermophoretic sorting technology has gradually attracted attention because it realizes sorting based on the differences in the motion behaviors of particles under a temperature gradient.

[0004] In thermophoretic sorting, the thermophoresis parameters of particles (such as the thermophoretic mobility D T ) are the core physical quantities characterizing their heat transport capabilities, directly affecting their transport behaviors under a temperature gradient, and are also the key indicators for understanding heat transport and the physical and chemical properties of particles. Accurately measuring the thermophoretic coefficient is of great significance for multiple directions, including: 1) revealing the transport mechanism of particles under a temperature gradient and promoting the theoretical understanding of non-equilibrium thermal diffusion phenomena; 2) distinguishing particles with different compositions, sizes, and surface properties to achieve rapid identification and classification; 3) studying the structures, stabilities, and interactions of biological particles such as proteins, DNA, and extracellular vesicles; 4) providing a basis for the design and parameter optimization of sorting systems to improve the accuracy and efficiency of particle sorting.

[0005] However, current technologies still face multiple challenges in thermophoresis parameter measurement and sorting. On the one hand, the construction of a stable and uniform temperature gradient field remains a key technical difficulty. Existing methods mostly use heating plates or laser-induced local heating, etc. Although local temperature increases can be achieved, the temperature distribution is uneven and difficult to adjust, which is not conducive to accurately measuring thermophoresis parameters, and may cause damage to temperature-sensitive samples due to local overheating, making it difficult to meet the requirements for obtaining high-quality data. On the other hand, most systems are difficult to accurately measure the thermophoresis parameters of particles and effectively sort different particles on the same platform; some systems with measurement capabilities, such as beam deflection and thermal field flow fractionation, usually have complex equipment, high costs, and cumbersome operations, making it difficult to be widely promoted in scientific research and applications.

[0006] Therefore, there is an urgent need for a microfluidic device and system with a simple structure, stable temperature control, and high functional integration. While providing a stable temperature gradient, it can measure the thermophoresis parameters of particles and efficiently separate different types of particles, providing a highly practical and reliable technical platform for related fields. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a microfluidic device and a microfluidic device system for measuring and sorting thermophoresis parameters of particles. Through the design of a microchannel and two heat exchange channels, it can establish a stable and uniform temperature gradient in the microchannel while measuring the thermophoresis parameters of particles and efficiently separating different types of particles.

[0008] To achieve the purpose of this invention, the following technical solutions are adopted:

[0009] In the first aspect, the present invention provides a microfluidic device for measuring and sorting thermophoresis parameters of particles. The microfluidic device includes a microchannel, a first heat exchange channel, a second heat exchange channel, a sample inlet, and a sample outlet;

[0010] The microchannel is arranged at the center of the microfluidic device;

[0011] Both ends of the microchannel are respectively communicated with the sample inlet and the sample outlet;

[0012] The first heat exchange channel and the second heat exchange channel are symmetrically arranged on both sides of the microchannel;

[0013] The flow directions of the heat exchange media in the first heat exchange channel and the second heat exchange channel are opposite.

[0014] In the present invention, the microchannel is used to place samples; the first heat exchange channel and the second heat exchange channel are used to circulate cold and hot media; the shapes of the microchannel, the first heat exchange channel, and the second heat exchange channel include rectangular or cylindrical.

[0015] The microfluidic device provided by the present invention, through the setting of the microchannel and two heat exchange channels, and the design of the two heat exchange channels as countercurrent cold and hot water channels, can generate a stable and uniform temperature gradient field in the central microchannel, which can be directly used for measuring and sorting the thermophoresis parameters of particles; simplifies the experimental process, reduces the system complexity and experimental cost, and improves the repeatability and applicability of the operation.

[0016] It should be noted that by setting two channels with countercurrent heat exchange on both sides of the microchannel, the temperature control of the microchannel can be achieved without complex laser heating equipment, avoiding the risk of local overheating; further, by adjusting the temperature and flow rate of the heat exchange media in the two channels on both sides, precise control of the size of the temperature gradient field can be realized.

[0017] As a preferred technical solution of the present invention, the aspect ratio of the microchannel is (4-10):1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1, etc.

[0018] It should be noted that by controlling the aspect ratio range of the microchannel, it is possible to adapt to micro-nano particles of different sizes and effectively suppress the generation of thermal convection.

[0019] Preferably, the width of the microchannel is 50-200μm, for example, it can be 60μm, 80μm, 100μm, 120μm, 140μm, 150μm, 160μm, 180μm, etc.

[0020] Preferably, the length of the microchannel is the same as the lengths of the first heat exchange channel and the second heat exchange channel.

[0021] In the present invention, the lengths of the microchannel and the two heat exchange channels are all in the centimeter order of magnitude.

[0022] As a preferred technical solution of the present invention, the heights of the first heat exchange channel and the second heat exchange channel are both 0.5-5mm, for example, it can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, etc.

[0023] Preferably, the widths of the first heat exchange channel and the second heat exchange channel are both 1-5mm, for example, it can be 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, etc.

[0024] In the present invention, the distance between the first heat exchange channel and the microchannel is 0.1-2mm, for example, it can be 0.2mm, 0.4mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.6mm, 1.8mm, etc.

[0025] As a preferred technical solution of the present invention, the microfluidic device further includes a first heat exchange medium inlet, a first heat exchange medium outlet, a second heat exchange medium inlet, and a second heat exchange medium outlet.

[0026] Preferably, the two ends of the first heat exchange channel are respectively communicated with the first heat exchange medium inlet and the first heat exchange medium outlet.

[0027] Preferably, the temperature of the first heat exchange medium is 0-10°C, for example, it can be 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, etc.

[0028] Preferably, the two ends of the second heat exchange channel are respectively communicated with the second heat exchange medium inlet and the second heat exchange medium outlet.

[0029] Preferably, the temperature of the second heat exchange medium is 60 - 150 °C, for example, it can be 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C or 145 °C, etc.

[0030] In the present invention, the heat exchange medium includes but is not limited to water, or a liquid medium with a wider application temperature range, such as silicone oil, to adapt to different working temperature ranges and heat conduction performance requirements.

[0031] As a preferred technical solution of the present invention, the first heat exchange channel and the second heat exchange channel are used to form a temperature gradient in the microchannel.

[0032] In the present invention, through the arrangement of the first heat exchange channel and the second heat exchange channel, a stable, uniform and controllable temperature gradient field can be generated in the transverse direction of the microchannel, and the temperature gradient is relatively large.

[0033] Preferably, the temperature gradient is 2×10 4 -5×10 5 K / m, for example, it can be 4×10 4 K / m, 6×10 4 K / m, 8×10 4 K / m, 1×10 5 K / m, 2×10 5 K / m or 4×10 5 K / m, etc.

[0034] As a preferred technical solution of the present invention, a slit is provided below the microchannel.

[0035] It should be noted that by providing a slit below the microchannel, heat loss can be reduced and the efficiency of temperature control can be improved.

[0036] Preferably, the distance between the microchannel and the slit is 100 - 200 μm, for example, it can be 120 μm, 140 μm, 160 μm or 180 μm, etc.

[0037] Preferably, the width of the slit is 0.5 - 2 mm, for example, it can be 0.6 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm or 1.8 mm, etc.

[0038] As a preferred technical solution of the present invention, the upper surfaces of the microchannel, the first heat exchange channel and the second heat exchange channel are all covered with a glue film or a cover glass.

[0039] In the present invention, the glue film includes an optical glue film.

[0040] It should be noted that both the microchannel and the two heat exchange channels are sealed with optical adhesive films or cover glasses to ensure the stability of the fluid and the accuracy of temperature control.

[0041] Preferably, the material of the microfluidic device includes stainless steel or PDMS.

[0042] In a second aspect, the present invention provides a microfluidic device system for particle thermophoresis parameter determination and sorting. The microfluidic device system includes a first driving device, a second driving device, a first heat exchange medium storage device, a second heat exchange medium storage device, a sample collection device, an imaging and monitoring unit, and the microfluidic device described in the first aspect;

[0043] The first driving device is connected to the sample inlet through a pipeline; the sample collection device is connected to the sample outlet through a pipeline;

[0044] The second driving device is independently connected to the first heat exchange medium outlet and the second heat exchange medium outlet through two pipelines respectively;

[0045] The first heat exchange medium storage device is connected to the first heat exchange medium inlet through a pipeline;

[0046] The second heat exchange medium storage device is connected to the second heat exchange medium inlet through a pipeline;

[0047] The imaging and monitoring unit is used for the determination of particle thermophoresis parameters and the real-time monitoring of the sorting of different particles.

[0048] The microfluidic device system provided by the present invention provides a stable and uniform temperature gradient for the microchannel through two heat exchange channels. Sample particles generate thermophoretic migration. Not only can the movement trajectory of the particles in the microchannel be observed and recorded in real time through the imaging and monitoring unit, and then various thermophoresis parameters of the particles can be calculated, but also particle sorting can be achieved by using the difference in particle thermophoretic response. The entire microfluidic device system has a compact integrated design and is easy to operate, and can simultaneously meet the accuracy and efficiency requirements of particle thermophoresis parameter determination and subsequent sorting experiments.

[0049] It should be noted that during the sorting of different particles, real-time monitoring can be carried out through the imaging and monitoring unit, and the sample perfusion rate and the cold and hot water suction flow rate can be adjusted in a timely manner according to the particle response situation to achieve the best sorting effect.

[0050] As a preferred technical solution of the present invention, the first driving device includes a single-channel syringe pump.

[0051] In the present invention, the single-channel syringe pump operates in a perfusion mode, injects the sample particle suspension into the microchannel through the sample inlet, and transports it to the sample collection device through the sample outlet after observation / sorting.

[0052] Preferably, the second driving device includes a dual-channel injection pump.

[0053] In the present invention, the dual-channel injection pump is used to synchronously control the flow of cold and hot water in the heat exchange channels on both sides in the microfluidic device. It operates in a pumping mode and draws cold and hot water from two independent storage devices. Meanwhile, the temperature of the water source in the storage device is monitored in real time by a thermometer to ensure the accuracy and stability of the experimental conditions.

[0054] Preferably, the pumping flow rate of the second driving device is 5 - 15 mL / min, for example, it can be 6 mL / min, 8 mL / min, 10 mL / min, 11 mL / min, 12 mL / min or 14 mL / min, etc.

[0055] As a preferred technical solution of the present invention, the imaging and monitoring unit includes a fluorescence microscope objective lens, a fluorescence microscopic imaging device and a computer that are connected in sequence.

[0056] Preferably, the fluorescence microscope objective lens is arranged below the microfluidic device.

[0057] Preferably, the fluorescence microscopic imaging device includes an electron multiplying CCD camera.

[0058] It should be noted that the basic principle of the determination of the particle thermophoresis parameters in the present invention is as follows:

[0059] A temperature gradient is established in the central microchannel Micro-nano particles migrate along the temperature gradient at a speed u T This migration along the temperature gradient is thermophoresis, and its thermophoretic velocity is defined by the following formula:

[0060]

[0061] where D T is the thermophoretic mobility, and this value depends on the properties of the particles themselves.

[0062] Furthermore, the Soret coefficient is used to describe the magnitude of thermophoresis of particles under steady state, and it is defined by the following formula:

[0063]

[0064] where D is the diffusion coefficient of the particles, which can be directly calculated from the Brownian diffusion model calculated.

[0065] The microfluidic device system in the present invention measures the thermophoretic velocity u of particles under a temperature gradient T and combines the temperature gradient value u T, the corresponding thermophoretic mobility D of the particles can be obtained T and the Soret coefficient S T , thereby realizing the non-destructive and accurate determination of the thermophoretic behavior parameters of the particles. Specifically, through the countercurrent heat exchange mode of the heat exchange channels on both sides of the microfluidic chip, a stable and controllable temperature gradient can be established in the central microchannel. By observing and recording the movement trajectories of the particles in the microchannel in real time through a microscope, and through the recording and analysis of the particle movement trajectories, the velocity in the temperature gradient direction (i.e., the thermophoretic velocity u T ) is extracted, and then various thermophoretic parameters of the particles (i.e., the thermophoretic mobility D T and the Soret coefficient S T ) are calculated. These parameters reflect the response ability of the particles in the temperature field and can be used to distinguish the thermophoretic characteristics of different types of particles. This method does not require pre-labeling or surface modification of the particles and can achieve non-destructive and accurate determination of thermophoretic parameters.

[0066] It should also be noted that the basic principle of particle sorting in the present invention is:

[0067] Since micro-nano particles with different properties have different thermophoretic mobilities D T , even under the same temperature gradient , they will exhibit different thermophoretic velocities u T . According to the differences in the thermophoretic coefficients of different particles, the present invention can further adjust key experimental parameters such as the temperature gradient intensity and flow rate of the system, thereby realizing the efficient and differential sorting of target particles. The micro-nano particles to be sorted do not require any pretreatment and are directly suspended in the solution. When the suspension flows through the microchannel, different particles exhibit differential response behaviors due to different thermophoretic mobilities. Specifically, particles with faster thermophoretic velocities will first migrate to the wall surface at the cold end or the hot end, while particles with slower thermophoretic velocities will be guided to the sorting sample particle collection pool. Subsequently, the other type of particles remaining in the central microchannel are collected secondarily. Through this continuous process, the differential sorting of target particles can be realized.

[0068] The present invention effectively improves the pertinence and controllability of the sorting process through the technical process of first measuring and then sorting. The determination of particle thermophoretic parameters not only provides basic data for the research on particle thermophoretic mechanisms and the analysis of particle transport behaviors, but also is an important basis for setting sorting conditions. This device system has the advantages of simple operation, good repeatability, high system integration, etc., and is applicable to multiple research and application fields such as life science, environmental analysis, and nano-material screening.

[0069] The present invention also provides a method for measuring and sorting particle thermophoresis parameters by using the microfluidic device system described in the second aspect. The method for measurement and sorting includes: injecting a sample to be measured into the microchannel through a first driving device, then injecting a first heat exchange medium and a second heat exchange medium into the first heat exchange channel and the second heat exchange channel respectively through a second driving device, so as to form a temperature gradient in the microchannel. The sample to be measured undergoes thermophoretic migration. Subsequently, an imaging and monitoring unit is used to analyze the particle movement trajectory in the microchannel and obtain the thermophoretic velocity. Finally, the thermophoresis parameters of the particles are calculated by combining the temperature gradient value. Then, sorting conditions can be set according to the thermophoresis parameters. Particles with a faster thermophoretic velocity preferentially migrate to the cold end or the hot end wall surface, while particles with a slower thermophoretic velocity remain in the main flow region of the microchannel fluid, enter the sample collection device through the sample outlet of the microchannel, and finally, the other kind of particles remaining in the microchannel are collected for the second time.

[0070] The numerical ranges described in the present invention not only include the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] (1) The microfluidic device provided by the present invention, through the setting of the microchannel and two heat exchange channels, and the design of the countercurrent cold and hot water channels for the two heat exchange channels, can generate a stable and uniform temperature gradient field in the microchannel, avoiding the risk of local overheating; at the same time, without surface modification or pretreatment of the sample particles, it can be directly used for the measurement and sorting of particle thermophoresis parameters, simplifying the experimental process, reducing the system complexity and experimental cost, and improving the operational repeatability and applicability;

[0073] (2) The microfluidic device provided by the present invention generates a mild and controllable temperature gradient field, has good biocompatibility, and will not have an adverse impact on the physical and chemical properties of the particles, and is particularly suitable for the sorting and analysis of temperature-sensitive biological particles;

[0074] (3) The microfluidic device system provided by the present invention, by establishing a stable and uniform temperature gradient field in the microfluidic device, combining particle trajectory tracking and analysis, not only realizes the real-time observation of the thermophoretic migration behavior of different micro-nano particles and the quantitative determination of thermophoresis parameters, but also can use the difference in particle thermophoretic response to achieve particle sorting, with high sorting efficiency and strong reliability, and is suitable for particle enrichment and purification in complex sample systems;

[0075] (4) The microfluidic device system provided by the present invention integrates the measurement of thermophoretic behavior parameters and the functional sorting ability, has both scientific research and application values, is applicable to multiple fields such as basic physics, biomedicine, environmental monitoring, and materials science, and has good promotion prospects and practical application potential. Description of the Drawings

[0076] Figure 1 It is a schematic structural diagram of the microfluidic device provided in Embodiment 1.

[0077] Figure 2 It is a top view of the microfluidic device provided in Embodiment 1.

[0078] Figure 3 It is a bottom view of the microfluidic device provided in Embodiment 1.

[0079] Figure 4 It is a schematic cross-sectional structural diagram of the microfluidic device provided in Embodiment 1.

[0080] Figure 5 It is a schematic structural diagram of the microfluidic device system provided in Embodiment 1.

[0081] Wherein, 1 - microchannel, 1 - a - sample inlet, 1 - b - sample outlet, 2 - first heat exchange channel, 2 - a - first heat exchange medium inlet, 2 - b - first heat exchange medium outlet, 3 - second heat exchange channel, 3 - a - second heat exchange medium outlet, 3 - b - second heat exchange medium inlet, 4 - slit, 5 - optical adhesive film, 6 - second driving device, 7 - first driving device, 8 - first heat exchange medium storage device, 9 - second heat exchange medium storage device, 10 - sample collection device, 11 - fluorescence microscope objective, 12 - fluorescence microscopic imaging device, 13 - computer, 100 - microfluidic device.

[0082] Figure 6 It is a temperature distribution diagram of fluorescence temperature measurement in the central region of the microchannel by the microfluidic device system provided in Embodiment 1.

[0083] Figure 7 It is a thermophoretic parameter test result diagram of the microfluidic device system provided in Embodiment 1 for testing the mixed suspension of polystyrene particles and silica particles and the mixed suspension of extracellular vesicles and protein condensates. Detailed Embodiments

[0084] It should be understood that in the description of the present invention, the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0085] It should be noted that in the description of the present invention, unless otherwise clearly specified and defined, the terms "set", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0086] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0087] Unless otherwise specified, the reagents used in the following examples and comparative examples are all commercially available products or can be prepared by known methods. In the following examples and comparative examples, the first heat exchange medium is water, and the second heat exchange medium is water or silicone oil.

[0088] Example 1

[0089] This example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. The microfluidic device (as Figures 1-4 shown) includes a microchannel 1, a first heat exchange channel 2, a second heat exchange channel 3, a sample inlet 1-a, a sample outlet 1-b, a first heat exchange medium inlet 2-a, a first heat exchange medium outlet 2-b, a second heat exchange medium inlet 3-b, and a second heat exchange medium outlet 3-a;

[0090] The microchannel 1 is arranged at the center of the microfluidic device; both ends of the microchannel 1 are respectively communicated with the sample inlet 1-a and the sample outlet 1-b; the width of the microchannel 1 is 200 μm, the height is 50 μm, and the length is 2.8 cm;

[0091] The first heat exchange channel 2 and the second heat exchange channel 3 are symmetrically arranged on both sides of the microchannel 1; both ends of the first heat exchange channel 2 are respectively communicated with the first heat exchange medium inlet 2-a and the first heat exchange medium outlet 2-b; both ends of the second heat exchange channel 3 are respectively communicated with the second heat exchange medium inlet 3-b and the second heat exchange medium outlet 3-a; the widths of both the first heat exchange channel 2 and the second heat exchange channel 3 are 2 mm, the heights are both 2 mm, and the lengths are both 2.8 cm;

[0092] The flow directions of the heat exchange media in the first heat exchange channel 2 and the second heat exchange channel 3 are opposite; the temperature of the first heat exchange medium is 0 °C; the temperature of the second heat exchange medium is 80 °C;

[0093] A slit 4 is arranged below the microchannel 1; the distance between the microchannel 1 and the slit 4 is 100 μm; the width of the slit 4 is 0.8 mm;

[0094] Optical adhesive films 5 with a thickness of 200 μm cover the upper surfaces of the microchannel 1, the first heat exchange channel 2, and the second heat exchange channel 3;

[0095] The microfluidic device is made of stainless steel.

[0096] The microfluidic device system (as Figure 5 shown) includes a first driving device 7, a second driving device 6, a first heat exchange medium storage device 8, a second heat exchange medium storage device 9, a sample collection device 10, an imaging and monitoring unit, and the aforementioned microfluidic device 100;

[0097] The first driving device 7 is connected to the sample injection port 1-a through a pipeline; the sample collection device 10 is connected to the sample outlet 1-b through a pipeline;

[0098] The second driving device 6 is respectively and independently connected to the first heat exchange medium outlet 2-b and the second heat exchange medium outlet 3-a through two pipelines; the first heat exchange medium storage device 8 is connected to the first heat exchange medium inlet 2-a through a pipeline; the second heat exchange medium storage device 9 is connected to the second heat exchange medium inlet 3-b through a pipeline;

[0099] The first driving device 7 is a single-channel syringe pump;

[0100] The second driving device 6 is a two-channel syringe pump; the suction flow rate of the second driving device is 5 mL / min;

[0101] The imaging and monitoring unit includes a fluorescence microscope objective lens 11, a fluorescence microscopic imaging device 12, and a computer 13 that are connected in sequence; the fluorescence microscope objective lens 11 is disposed below the microfluidic device; the fluorescence microscopic imaging device 12 is an electron multiplying CCD camera.

[0102] Example 2

[0103] This embodiment provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. The microfluidic device includes a microchannel, a first heat exchange channel, a second heat exchange channel, a sample inlet, a sample outlet, a first heat exchange medium inlet, a first heat exchange medium outlet, a second heat exchange medium inlet, and a second heat exchange medium outlet.

[0104] The microchannel is disposed at the center of the microfluidic device; both ends of the microchannel are respectively communicated with the sample inlet and the sample outlet; the width of the microchannel is 200 μm, the height is 20 μm, and the length is 1.2 cm.

[0105] The first heat exchange channel and the second heat exchange channel are symmetrically disposed on both sides of the microchannel; both ends of the first heat exchange channel are respectively communicated with the first heat exchange medium inlet and the first heat exchange medium outlet; both ends of the second heat exchange channel are respectively communicated with the second heat exchange medium inlet and the second heat exchange medium outlet; the widths of the first heat exchange channel and the second heat exchange channel are both 1 mm, the heights are both 0.5 mm, and the lengths are both 1.2 cm.

[0106] The flow directions of the heat exchange media in the first heat exchange channel and the second heat exchange channel are opposite; the temperature of the first heat exchange medium is 0 °C; the temperature of the second heat exchange medium is 150 °C.

[0107] A slit is disposed below the microchannel; the distance between the microchannel and the slit is 200 μm; the width of the slit is 0.5 mm.

[0108] Cover glasses with a thickness of 150 μm cover the upper surfaces of the microchannel, the first heat exchange channel, and the second heat exchange channel.

[0109] The microfluidic device is made of PDMS.

[0110] The microfluidic device system includes a first driving device, a second driving device, a first heat exchange medium storage device, a second heat exchange medium storage device, a sample collection device, an imaging and monitoring unit, and the aforementioned microfluidic device.

[0111] The first driving device is connected to the sample inlet through a pipeline; the sample collection device is connected to the sample outlet through a pipeline.

[0112] The second driving device is independently connected to the first heat exchange medium outlet and the second heat exchange medium outlet through two pipelines respectively; the first heat exchange medium storage device is connected to the first heat exchange medium inlet through a pipeline; the second heat exchange medium storage device is connected to the second heat exchange medium inlet through a pipeline;

[0113] The first driving device is a single-channel syringe pump;

[0114] The second driving device is a double-channel syringe pump; the suction flow rate of the second driving device is 10 mL / min;

[0115] The imaging and monitoring unit includes a fluorescence microscope objective lens, a fluorescence microscopic imaging device and a computer connected in sequence; the fluorescence microscope objective lens is arranged below the microfluidic device; the fluorescence microscopic imaging device is an electron multiplying CCD camera.

[0116] Example 3

[0117] This example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. Except that the width of the microchannel is 300 μm and the height is 20 μm, other conditions are the same as those in Example 1.

[0118] Example 4

[0119] This example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. Except that the width of the microchannel is 50 μm and the height is 50 μm, other conditions are the same as those in Example 1.

[0120] Example 5

[0121] This example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. Except that no slit is provided below the microchannel, other conditions are the same as those in Example 1.

[0122] Example 6

[0123] This example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. Except that the distance between the slit and the microchannel is 500 μm, other conditions are the same as those in Example 1.

[0124] Comparative Example 1

[0125] This comparative example provides a microfluidic device and a microfluidic device system for measuring and sorting particle thermophoresis parameters. Except that the flow directions of the heat exchange media in the first heat exchange channel and the second heat exchange channel are the same, other conditions are the same as those in Example 1.

[0126] Using the microfluidic device system provided by the above embodiments and comparative examples, a temperature-sensitive fluorescent reagent was perfused through a single-channel syringe pump, and the dual-channel syringe pump was turned on to simultaneously suck the first heat exchange medium and the second heat exchange medium. The temperature gradient formed in the central region of the microchannel was tested by fluorescence thermometry, and the test results are as follows Figure 6 and shown in Table 1.

[0127] It should be noted that Figure 6 the temperature values marked in Table 1 are the measurement results in the central region of the microchannel and do not represent the temperature distribution in the entire microchannel.

[0128] Table 1

[0129]

[0130]

[0131] As can be seen from Table 1:

[0132] (1) For the microfluidic device and system provided in Embodiments 1-2 of the present invention, through the setting of the microchannel and two heat exchange channels, and the two heat exchange channels adopt a countercurrent cold and hot water channel design, maintaining a relatively high temperature difference along the heat exchange path all the time, improving the heat transfer efficiency and the outlet temperature difference, achieving a better heat energy utilization effect, so as to be able to generate a stable and uniform temperature gradient field in the central microchannel, and its temperature gradient is relatively large, and then accurately measure and efficiently sort the thermophoresis parameters of micro-nano particles;

[0133] (2) By comparing Embodiment 1 with Embodiments 3-4, it can be seen that although a temperature gradient can be established in the microchannel whether the aspect ratio is relatively large or small, it is found in the actual experiment process that if the aspect ratio of the microchannel is too large, due to the increase in fluid pressure drop and the limitation of liquid flow, it may affect the stable operation of the system; while when the aspect ratio is too small, the temperature gradient per unit length of the microchannel in the height direction has a significant amplitude, and natural convection is likely to occur, thus interfering with the thermophoresis behavior of particles in the temperature gradient field and reducing the measurement and sorting accuracy;

[0134] (3) By comparing Embodiment 1 with Embodiments 5-6, it can be seen that if there is no slit structure under the microchannel or the distance between the slit and the microchannel is too large, due to the increase in heat loss of the system and the reduction of temperature control efficiency, both will lead to the weakening of the temperature gradient formed in the microchannel, and then affect the thermophoresis behavior of particles in the temperature field, reducing the accuracy of thermophoresis measurement and the efficiency and stability of particle sorting;

[0135] (4) It can be seen from the comparison between Example 1 and Comparative Example 1 that when the flow directions of the heat exchange media in the first heat exchange channel and the second heat exchange channel are the same, although the central region is not much different from that in Example 1, since the cold and hot fluids enter from the same end and flow in parallel in the same direction, it causes the two to gradually approach thermal equilibrium during the heat exchange process, resulting in a small outlet temperature difference, a reduced heat exchange driving force, and a low heat utilization rate. At the same time, under this structure, the temperature difference distribution is uneven along the flow direction of the microchannel during the heat exchange process, showing a trend of "large temperature difference in the front section and small temperature difference in the rear section", which affects the overall heat exchange efficiency.

[0136] Determination and sorting of particle thermophoresis parameters

[0137] The microfluidic device system provided in Example 1 was used to respectively perform the determination and sorting of the thermophoresis parameters of the mixed suspension of polystyrene particles and silica particles and the mixed suspension of extracellular vesicles and protein condensates (PGL-3).

[0138] The method for the determination and sorting of the thermophoresis parameters of the mixed suspension of polystyrene particles and silica particles is as follows:

[0139] The mixed suspension of polystyrene particles (with a diameter of 0.5 μm) and silica particles (with a diameter of 0.5 μm) was injected into the microchannel through the first driving device, and then the first heat exchange medium and the second heat exchange medium were respectively sucked into the first heat exchange channel and the second heat exchange channel through the second driving device. The cold and hot heat exchange media began to circulate, and then a temperature gradient was formed in the microchannel. Under the action of the temperature gradient, the mixed suspension of polystyrene particles and silica particles underwent thermophoretic migration. The movement trajectories of the particles in the microchannel were observed and recorded in real time through the imaging and monitoring unit. Subsequently, the collected particle movement trajectories were analyzed to obtain their thermophoretic velocity u T , and combined with the temperature gradient obtained from the experiment to calculate various thermophoresis parameters of the particles (as Figure 7 shown);

[0140] As Figure 7 can be seen, polystyrene particles have a large positive thermophoretic mobility, while silica particles have a small negative thermophoretic mobility. After setting the sorting conditions according to the thermophoresis parameters, the polystyrene particles with a faster thermophoretic velocity preferentially migrate to the cold or hot end wall, while the silica particles with a slower thermophoretic velocity remain in the main flow region of the microchannel fluid, enter the sample collection device through the microchannel sampling port, and finally the remaining polystyrene particles in the microchannel are collected for the second time.

[0141] The method for the determination and sorting of the thermophoresis parameters of the mixed suspension of extracellular vesicles and protein condensates (PGL-3) is as follows:

[0142] A suspension mixture of extracellular vesicles (with a diameter of 0.5 - 0.8 μm) and protein condensates (with a diameter of 1.5 - 2.0 μm) is injected into the microchannel through a first driving device. Then, a first heat exchange medium and a second heat exchange medium are respectively sucked into a first heat exchange channel and a second heat exchange channel through a second driving device. The hot and cold heat exchange media start to circulate, and then a temperature gradient is formed in the microchannel. Under the action of the temperature gradient, the suspension mixture of extracellular vesicles and protein condensates undergoes thermophoretic migration. The movement trajectories of the particles in the microchannel are observed and recorded in real time through an imaging and monitoring unit. Subsequently, the collected particle movement trajectories are analyzed to obtain their thermophoretic velocity u T , and combined with the temperature gradient obtained from the experiment to calculate various thermophoretic parameters of the particles (as Figure 7 shown);

[0143] such as Figure 7 it can be seen that the thermophoretic mobility of protein condensates is four times that of extracellular vesicles. After setting the sorting conditions according to the thermophoretic parameters, the protein condensates with a faster thermophoretic velocity preferentially migrate to the cold or hot end wall, while the extracellular vesicles with a slower thermophoretic velocity remain in the main flow region of the microchannel fluid, enter the sample collection device through the microchannel sample outlet, and finally the remaining protein condensates in the microchannel are collected again.

[0144] During the entire experimental process, the average temperature of the microchannel is 36 °C, indicating that the entire sorting process is completed on the premise of maintaining the biological cell activity and integrity, providing a guarantee for subsequent particle research and applications.

[0145] In summary, the microfluidic device and system provided by the present invention can accurately measure and sort the thermophoretic parameters of particles by setting two channels with countercurrent heat exchange on both sides of the microchannel, without the need for complex laser heating equipment. In addition, through the technical process of first measuring and then sorting, the pertinence and controllability of the sorting process are effectively improved. The measurement of particle thermophoretic parameters not only provides basic data for the research of particle thermophoretic mechanisms and the analysis of particle transport behaviors, but also is an important basis for setting sorting conditions. The microfluidic device system has the advantages of simple operation, good repeatability, high system integration, etc., and is applicable to multiple research and application fields such as life science, environmental analysis, and nanomaterial screening.

[0146] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A microfluidic device for measuring and sorting particle thermophoresis parameters, characterized in that The microfluidic device includes a microchannel, a first heat exchange channel, a second heat exchange channel, a sample inlet, and a sample outlet; The microchannel is disposed at the center of the microfluidic device; Both ends of the microchannel are respectively communicated with the sample inlet and the sample outlet; The first heat exchange channel and the second heat exchange channel are symmetrically arranged on both sides of the microchannel; The flow directions of the heat exchange media in the first heat exchange channel and the second heat exchange channel are opposite; 2. The microfluidic device according to claim 1, wherein The aspect ratio of the microchannel is (4 - 10):1; Preferably, the width of the microchannel is 50 - 200 μm; Preferably, the length of the microchannel is the same as the lengths of the first heat exchange channel and the second heat exchange channel; 3. The microfluidic device according to claim 1 or 2, characterized in that, The heights of the first heat exchange channel and the second heat exchange channel are both 0.5 - 5 mm; Preferably, the widths of the first heat exchange channel and the second heat exchange channel are both 1 - 5 mm; 4. The microfluidic device according to any one of claims 1 to 3, characterized in that The microfluidic device further includes a first heat exchange medium inlet, a first heat exchange medium outlet, a second heat exchange medium inlet, and a second heat exchange medium outlet; Preferably, both ends of the first heat exchange channel are respectively communicated with the first heat exchange medium inlet and the first heat exchange medium outlet; Preferably, the temperature of the first heat exchange medium is 0 - 10 °C; Preferably, both ends of the second heat exchange channel are respectively communicated with the second heat exchange medium inlet and the second heat exchange medium outlet; Preferably, the temperature of the second heat exchange medium is 60 - 150 °C; 5. The microfluidic device according to any one of claims 1-4, characterized in that, The first heat exchange channel and the second heat exchange channel are used to form a temperature gradient in the microchannel; Preferably, the temperature gradient is 2×10 4 -5×10 5 K / m.

6. The microfluidic device according to any one of claims 1-5, characterized in that, A slit is disposed below the microchannel; Preferably, the distance between the microchannel and the slit is 100 - 200 μm; Preferably, the width of the slit is 0.5 - 2 mm; 7. The microfluidic device according to any one of claims 1-6, characterized in that, The upper surfaces of the microchannel, the first heat exchange channel, and the second heat exchange channel are all covered with a glue film or a cover glass; Preferably, the material of the microfluidic device includes stainless steel or PDMS; 8. A microfluidic device system for determining and sorting particle thermophoresis parameters, characterized in that, The microfluidic device system includes a first driving device, a second driving device, a first heat exchange medium storage device, a second heat exchange medium storage device, a sample collection device, an imaging and monitoring unit, and the microfluidic device according to any one of claims 1 - 7; The first driving device is connected to the sample inlet through a pipeline; the sample collection device is connected to the sample outlet through a pipeline; The second driving device is respectively independently connected to the first heat exchange medium outlet and the second heat exchange medium outlet through two pipelines; The first heat exchange medium storage device is connected to the first heat exchange medium inlet through a pipeline; The second heat exchange medium storage device is connected to the second heat exchange medium inlet through a pipeline; The imaging and monitoring unit is used for the determination of particle thermophoresis parameters and the real - time monitoring of different particle sorting; 9. The microfluidic device system according to claim 8, characterized in that, The first driving device includes a single - channel syringe pump; Preferably, the second driving device includes a double - channel syringe pump; Preferably, the suction flow rate of the second driving device is 5 - 15 mL / min; 10. The microfluidic device system according to claim 8 or 9, characterized in that, The imaging and monitoring unit includes a fluorescence microscope objective lens, a fluorescence microscopic imaging device, and a computer connected in sequence; Preferably, the fluorescence microscope objective lens is disposed below the microfluidic device; Preferably, the fluorescence microscopy imaging device includes an electron multiplying CCD camera.

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