Micro-nano particle thermophoresis experiment system with controllable temperature gradient

Abstract

The invention provides a temperature gradient controllable micro-nano particle thermophoresis experiment system, which comprises a micro-channel module, the micro-channel module is provided with a bearing part and a plurality of groups of micro-channel parts which are arranged on the bearing part and can bear a to-be-tested particle suspension, and the plurality of groups of micro-channel parts have different size parameters; the temperature control module is provided with a temperature control part, a temperature conduction part connected with the temperature control part and a temperature detection part connected with the bearing part; the microscopic imaging module is provided with an acquisition part and a processing part connected with the acquisition part; and the acquisition part is opposite to the center of the micro-channel part. According to the micro-nano particle thermophoresis experiment system with the controllable temperature gradient, a linear temperature gradient module with high stability, flexibility and controllability can be constructed in a liquid phase environment, and the micro-nano particle thermophoresis experiment system is particularly suitable for researching a thermophoresis physical mechanism of micro-particles in a thermal field by combining a plurality of groups of micro-channel size structures and a microscopic imaging analysis module.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace technology, in particular to a micro-nanoparticle thermophoresis experimental system with controllable temperature gradient. BACKGROUND

[0002] In the prior art, thermophoresis, as a particle migration mechanism driven by temperature gradient, has been widely used in various engineering and scientific fields, covering a wide range of scenarios from environmental governance to precision medicine.

[0003] For example, in the field of air purification and dust removal, researchers use thermophoresis to improve the adsorption efficiency of sub-micron particles. Typical structures include channel devices with different temperature walls, such as the double-cold-wall particle thermophoresis sedimentation device disclosed in patent No. CN201521040652; and the heating adsorption device disclosed in patent No. CN201610884774.

[0004] In the direction of micro-nano manipulation, thermophoresis is integrated into photothermal systems, such as the particle manipulator based on photothermal waveguide disclosed in patent No. CN202311848410. The photothermal waveguide written by laser can interact with light to generate a local heat source, which can be used for particle manipulation. For example, the optical tweezers device based on photothermal diffusion thermophoresis disclosed in patent No. CN202210444630.

[0005] Thermophoresis is also used for the separation and concentration detection of sub-micron particles, such as the circulating channel particle concentration detection device disclosed in patent No. CN201880049207; and the device for separating nanoparticles according to their electrical conductivity disclosed in patent No. CN200810166165.

[0006] In the direction of biomolecule detection, thermophoresis technology can selectively enrich and enhance the signal strength of extremely low concentration targets in blood and body fluids. For example, the liver cancer detection system and method for thermophoresis extracellular vesicle detection disclosed in patent No. CN201811321676 includes a heating unit for heating extracellular vesicles in the blood of the subject to be tested; a sample chamber unit is arranged on one side of the heating unit; and a signal processing unit is arranged on one side of the sample chamber unit.

[0007] In summary, the current thermophoresis technology development has gone from single phenomenon observation to multi-field coupling, structure integration and practical application stage. The core is how to stably build a temperature gradient field and controllably use the particle response behavior. However, the existing thermophoresis related technology has been widely explored in many application scenarios such as air purification, particle enrichment, and biological molecule manipulation, but the overall still takes the functional implementation as the guidance, and pays more attention to whether the thermophoresis as a driving force can be used or not, and the controllability and analyzability of the nature of the thermophoresis physical mechanism are insufficient.

[0008] Specifically, many existing devices have deficiencies in the design of the temperature control system. A non-uniform temperature difference is often established by simplifying the structure or locally heating, which cannot realize accurate, stable and controllable temperature gradient, which directly limits the quantitative analysis and repeated verification of the thermophoresis driving force. At the same time, due to the lack of continuous measurement and feedback control of the temperature field distribution, the difference of the particle migration path is often misjudged as the difference of the particle characteristics, which cannot be used to extract the required parameters such as the thermophoresis speed and the Soret coefficient.

[0009] In terms of structure, most of the existing systems adopt a single size and fixed geometry channel, which is difficult to reveal the scale-dependent migration behavior of particles in a restricted microchannel due to interface effects, fluid layer thickness changes and other factors, and also lacks the ability to regulate the uniform temperature field in the transverse comparison structure.

[0010] Therefore, there is an urgent need for a micro-nano particle thermophoresis experimental system with controllable temperature gradient to solve the technical problems existing in the prior art to some extent. SUMMARY

[0011] The present application provides a micro-nano particle thermophoresis experimental system with controllable temperature gradient, which can construct a linear temperature gradient module with high stability and flexible controllability in a liquid environment, combined with multiple microchannel size structures and microscopic imaging analysis modules, especially suitable for studying the thermophoresis physical mechanism of micro-particles in a thermal field.

[0012] The present application provides a micro-nano particle thermophoresis experimental system with controllable temperature gradient; comprising: A microchannel module has a bearing part and a microchannel part capable of loading a particle suspension to be tested arranged on the bearing part, and the microchannel part has multiple groups, and the multiple groups of the microchannel part have different size parameters. A temperature control module has a temperature control part, a temperature conduction part connected with the temperature control part and arranged on the bearing part at a first preset position, and a temperature detection part connected with the bearing part at a second preset position and forming a closed-loop temperature control with the temperature control part; the temperature control part controls the temperature conduction part to output a target temperature to the bearing part; the temperature detection part can detect a feedback temperature of the bearing part, and the temperature control part adjusts and controls the target temperature and the feedback temperature to enable the microchannel part to establish a stable thermal field. A microscopic imaging module has a collection part and a processing part connected with the collection part; the collection part is opposite to the center of the microchannel part to collect the movement process of the particles in the particle suspension; the processing part can process and analyze the movement process of the particles in the particle suspension collected by the collection part.

[0013] In the above technical solution, further, the bearing part is an experimental plate. The experimental plate is a stainless steel experimental plate, and the stainless steel experimental plate is provided with a mounting position, and the microchannel part is arranged in the mounting position.

[0014] In the above technical solution, further, the microchannel module includes a plurality of microchannel plates. The microchannel plates are provided with microchannels spaced apart along a first direction; and the aspect ratios of the microchannels on the plurality of microchannel plates are arranged in an array.

[0015] In the above technical solution, further, the temperature gradient controllable micro-nano particle thermophoresis experimental system further includes an optical sealing film. The optical sealing film covers the experimental plate and is sealed to the experimental plate at a preset pressure to seal the microchannel plate containing the particle suspension.

[0016] In the above technical solution, further, the temperature control part is a temperature controller, and the temperature conduction part is a semiconductor thermoelectric sheet; the temperature control part includes a thermocouple and a temperature measuring instrument. The semiconductor thermoelectric sheets are a plurality of semiconductor thermoelectric sheets arranged on the experimental plate at the first preset position; and the temperature controller controls the semiconductor thermoelectric sheets to output a target temperature to the experimental plate. The number of the thermocouples is the same as the number of the semiconductor thermoelectric sheets, and the thermocouples are connected to the experimental plate at the second preset position. The temperature measuring instrument is connected with the thermocouples, and the feedback temperature of the experimental plate can be detected through the thermocouples. The temperature controller adjusts and controls the target temperature and the feedback temperature to enable the microchannel part to establish a stable thermal field.

[0017] Further, the temperature control module further comprises a heat-conducting silicone grease layer. The heat-conducting silicone grease layer is arranged between the semiconductor thermoelectric sheet and the experimental plate to reduce the contact thermal resistance between the semiconductor thermoelectric sheet and the experimental plate and to evenly transmit the heat from the semiconductor thermoelectric sheet to the experimental plate.

[0018] Further, the temperature control module further comprises a power supply, and the power supply is a double-channel power supply; the semiconductor thermoelectric sheet and the thermocouple are both two. The temperature controller is a double-channel temperature controller, and the double-channel temperature controller is connected with the two semiconductor thermoelectric sheets respectively to control the semiconductor thermoelectric sheets respectively. The temperature measuring instrument is a double-channel temperature measuring instrument, and the double-channel temperature measuring instrument is connected with the two thermocouples respectively to detect the feedback temperatures fed back by the two thermocouples respectively.

[0019] Further, the collecting part comprises a fluorescence inverted microscope and a camera, and the processing part is a computer. The fluorescence inverted microscope is arranged at the center of the microchannel part; and the camera is used to record the movement process of the particles to be measured in the particle suspension and form an image. The computer analyzes the image and outputs the migration direction, displacement curve and speed data of the particles to be measured.

[0020] Further, the microscopic imaging module further comprises a fluorescence excitation light source. The particle suspension to be measured is added with green fluorescence modified polystyrene particles to track the movement state of the particles. When the movement process of the particles to be measured in the particle suspension to be measured is collected by the collecting part, the fluorescence excitation light source is modulated to a fluorescence channel matched with the particles to be measured in the particle suspension to be measured.

[0021] Compared with the prior art, the present application has the following beneficial effects: The present application provides a micro-nano particle thermophoresis experimental system with controllable temperature gradient; comprising: A microchannel module has a bearing part and a microchannel part arranged on the bearing part and capable of containing a particle suspension to be measured, and the microchannel part has multiple groups, and the multiple groups of the microchannel part have different size parameters. The temperature control module has a temperature control part, a temperature conduction part connected with the temperature control part and arranged on the bearing part at a first preset position, and a temperature detection part connected with the bearing part at a second preset position and forming a closed loop temperature control with the temperature control part; the temperature control part controls the temperature conduction part to output a target temperature to the bearing part; the temperature detection part can detect a feedback temperature of the bearing part, and the temperature control part adjusts and controls the target temperature and the feedback temperature, so that the microchannel part can establish a stable thermal field. The microscopic imaging module has a collection part and a processing part connected with the collection part; the collection part is opposite to the center of the microchannel part to collect the movement process of the particles in the particle suspension; and the processing part can process and analyze the movement process of the particles in the particle suspension collected by the collection part.

[0022] In summary, the application forms a stable temperature control platform by arranging symmetrically distributed semiconductor thermoelectric sheets and high thermal conductivity stainless steel experimental plates, ensures the formation of a continuous and controllable linear temperature gradient in the microchannel, maintains good stability in spatial distribution and time dimension, and provides clear driving force conditions for particle thermophoresis behavior. In addition, two semiconductor thermoelectric sheets are used for heating and refrigeration respectively, and are tightly attached to the stainless steel experimental plate through heat-conducting silicone grease, and a closed loop control circuit is formed by combining a thermocouple and a temperature controller, which can realize stable, stable in time, linear adjustable temperature gradient output in the micron scale experimental area.

[0023] Secondly, the microchannel structure group design makes it have multiple size parameters to choose from, supporting systematic research on structure size variables. The channel group is arranged in the same temperature control area, and cooperates with the unified temperature control conditions, so that the particles in different size channels receive consistent thermal field, which is conducive to efficient comparative experiments.

[0024] Secondly, the sample injection is simple and convenient, and the top sealing film structure meets the sealing and optical imaging requirements. The inverted fluorescence microscope imaging system cooperates with the fluorescently labeled particles to realize high-resolution visualization recording of the thermophoresis path of the particles; the supporting image processing algorithm can accurately identify and parameterize the particle trajectory, and output the movement speed, direction and thermal response law.

[0025] Finally, the application has compact structure and simple operation, and is especially suitable for carrying out quantitative research on microscale thermophoresis physical mechanism in water phase or liquid phase medium, providing a key experimental platform for exploring thermophoresis law, building mathematical model and verifying physical mechanism, and has good scientific research applicability and development potential. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings needed to be used in the description of the specific embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort.

[0027] Figure 1 The structure schematic diagram of the temperature gradient controllable micro-nanoparticle thermophoresis experimental system provided by the present application is shown in the figure. Figure 2 The structure schematic diagram of the experimental plate and the temperature measuring instrument in the temperature gradient controllable micro-nanoparticle thermophoresis experimental system provided by the present application is shown in the figure. Figure 3 The temperature control schematic diagram of the temperature gradient controllable micro-nanoparticle thermophoresis experimental system provided by the present application is shown in the figure. (a) shows the theoretical temperature curve designed to ensure that different channels are subjected to the same thermal field conditions (temperature gradient and average temperature) during the experiment. Figure 4 The imaging effect diagram of the particles in the particle suspension to be measured provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0028] The following detailed description is presented to aid the reader in gaining a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, various changes, modifications, and equivalents thereof could become apparent to the reader familiar with the disclosure of this application. For example, the order in which steps are presented herein are merely examples and the steps can be performed in any order necessary to achieve the results described herein, except where order is specifically required by a step. Also, descriptions of features in terms of being performed in response to operations or changing states are intended to be interpreted as being performed in the order in which the operations or states are described, unless otherwise noted. Moreover, for the purpose of clarity and the convenience of the reader, the descriptions of features can omit certain features that are known in the art. The features described herein could be implemented in a wide variety of ways. Any feature described herein could be implemented in the way described herein, or in any other way. Further, to facilitate a clear understanding of the present disclosure, many of the details of the methods, apparatuses, and / or systems have been simplified and have been presented only as briefly as possible. For example, some apparatuses have been shown without certain features, or with only certain features, to avoid confusing the reader with details not necessary for understanding the present disclosure. The skilled artisan will understand, or be able to determine, how certain features of the described apparatuses, systems and / or methods can be implemented with the disclosure. As will be apparent, certain features of the application can be practiced without collecting all the data to which the features are applicable. Also, to avoid needless detail level confusion, the descriptions have been presented in terms of the preferred embodiments, or in terms of a single embodiment, as appropriate, and the skilled artisan will understand that variations on those preferred or single embodiments are within the scope of the present disclosure. Throughout this specification, when an element (such as a layer, region, or substrate) is referred to as being "on" another element, connected to another element, coupled to another element, positioned on another element, or covering another element, it can be directly on, connected to, coupled to, positioned on, or covering the other element or one or more other elements can be interposed therebetween. In contrast, when an element is referred to as being "directly on," "directly connected to," "directly coupled to," "directly positioned on," or "directly covering" another element, there are no other elements interposed therebetween. As used herein, the term "and / or" includes any one of the listed items and any combination of two or more of the listed items. Although the terms "first," "second," and "third" can be used herein to describe various elements, components, regions, layers, or sections, these elements, components, regions, layers, or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section described herein could also be termed a second element, component, region, layer, or section without departing from the teachings of the examples. Spatially relative terms, such as "beneath," "below," "lower," "above," "upper," and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Such spatially relative terms can be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "beneath" or "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.Accordingly, the term "over" as used herein includes both "above" and "below" as well as horizontal levels like in "on top of." The device can also be otherwise oriented (e.g., turned 90 degrees or at other orientations) and terminology used herein will be interpreted accordingly. The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and allow for other items to be present. As used herein, including the claims "or" as used in a phrase such as "A or B" means "A or B or both". As used herein, including the claims the term "including" means "including without limitation". As used herein, including the claims the term "coupled" means directly coupled, or indirectly coupled through one or more intervening components. Any example of a component can be replaced by any other component that serves a similar purpose. The examples described herein are not meant to be limiting. Other examples will become apparent to those skilled in the art upon reading this disclosure.

[0029] The present application is based on the construction of an experimental system based on the thermophoresis effect, which can be used to study the directional migration behavior of suspended particles in a liquid phase environment driven by a temperature gradient. Thermophoresis is a non-equilibrium mass transfer process, when particles are in a fluid medium with a temperature gradient, they will be subjected to a net force in the direction of the temperature gradient, resulting in directional thermophoretic motion. At the microscale, the particle thermophoretic velocity is affected by many factors, including particle properties (such as size, material, surface modification), environmental conditions (solution type, temperature), and the size and distribution of the temperature gradient. In order to achieve clear identification, parameter quantification and controllable reproduction of thermophoresis behavior in experiments, it is necessary to construct an experimental system that can output a stable linear temperature gradient, support different structural scales, and have high-resolution imaging capabilities. The present application is based on this principle goal, and a set of temperature controllable, microchannel size adjustable and fluorescence microscopic imaging integrated thermophoresis experimental system is developed. The system can establish a stable thermal field in a micron-scale channel, and analyze the thermophoretic behavior of particles through image tracking, thereby providing accurate experimental basis for thermophoretic physical mechanism analysis. The temperature controllable micro-nano particle thermophoresis experimental system will be described in detail below. Figures 1-4 The temperature controllable micro-nano particle thermophoresis experimental system is described in detail.

[0030] The temperature controllable micro-nano particle thermophoresis experimental system is described in detail. Figure 1 And Figure 2 As shown in FIGS. 1-3, the temperature controllable micro-nano particle thermophoresis experimental system includes a microchannel module having a bearing portion and a microchannel portion disposed on the bearing portion and capable of loading a particle suspension to be tested. The microchannel portion has multiple groups, and the multiple groups of the microchannel portion have different size parameters.

[0031] Specifically, the bearing part is an experimental plate; optionally, the experimental plate is a stainless steel experimental plate. Optionally, the stainless steel experimental plate is provided with a mounting position at the middle position, and the micro-channel part is arranged at the mounting position. Preferably, the mounting position refers to that a mounting groove is formed in the middle of the stainless steel experimental plate, and the micro-channel part can be arranged in the mounting groove, and more preferably, the mounting groove and the micro-channel part are matched in an interference manner. It is worth noting that: in the actual use process, the micro-channel part can also be directly formed on the experimental plate, that is, the micro-channel part is directly formed on the experimental plate.

[0032] Specifically, the micro-channel module comprises a plurality of micro-channel plates; the micro-channels are arranged at intervals in the first direction on the micro-channel plate, and the first direction herein is preferably the length direction of the experimental plate; the aspect ratios of the micro-channels on the plurality of micro-channel plates are arranged in an array, that is, the aspect ratios of the micro-channels on the plurality of micro-channel plates are different, so that the application can obtain the movement process of the particles in the particle suspension to be tested on micro-channels of different sizes.

[0033] Specifically, the temperature gradient controllable micro-nanoparticle thermophoresis experimental system further comprises an optical sealing film; the optical sealing film covers the experimental plate and is sealed to the experimental plate at a predetermined pressure to seal the micro-channel plate containing the particle suspension to be tested. Further, in the actual use process, a transparent optical sealing film is taken and evenly covered on the top of the micro-channel, and then a light pressure is applied on the film surface to ensure that the optical sealing film is tightly attached to the edge of the experimental plate, so as to avoid evaporation of the particle suspension to be tested and subsequent imaging interference.

[0034] In combination with Figure 1 and Figure 2 It is shown that the temperature gradient controllable micro-nanoparticle thermophoresis experimental system further comprises a temperature control module having a temperature control part, a temperature conduction part connected with the temperature control part and arranged on the bearing part at a first predetermined position, and a temperature detection part connected with the bearing part at a second predetermined position and constituting a closed-loop temperature control with the temperature control part. Among them, the temperature control part controls the temperature conduction part to output a target temperature to the bearing part; the temperature detection part can detect the feedback temperature of the bearing part, and the temperature control part adjusts the target temperature and the feedback temperature to enable the micro-channel part to establish a stable thermal field.

[0035] Specifically, the temperature control part is a temperature controller, and the temperature conduction part is a semiconductor thermoelectric sheet; the temperature control part comprises a thermocouple and a temperature measuring instrument; still in combination with Figure 1 It is shown that the semiconductor thermoelectric sheet is a plurality of semiconductor thermoelectric sheets arranged at the first predetermined position on the experimental plate; preferably, the first predetermined position is at the two ends of the experimental plate and at the first end surface of the experimental plate, and the temperature controller can control the semiconductor thermoelectric sheet to output a target temperature to the experimental plate.

[0036] Specifically, the number of thermocouples is the same as the number of semiconductor thermoelectric pieces, and the thermocouples are connected to the experimental plate at the second preset position; the temperature measuring instrument is connected to the thermocouples, and the feedback temperature of the experimental plate can be detected through the thermocouples; the temperature controller regulates the target temperature and the feedback temperature, so that the microchannel part can establish a stable thermal field. Preferably, the second preset position is formed at the second end face of the experimental plate opposite to the first end face. Preferably, the thermocouples correspond one-to-one to the semiconductor thermoelectric pieces.

[0037] Specifically, the temperature control module further comprises a heat-conducting silicone grease layer; the heat-conducting silicone grease layer is arranged between the semiconductor thermoelectric piece and the experimental plate to reduce the contact thermal resistance between the semiconductor thermoelectric piece and the experimental plate and to evenly transmit the heat from the semiconductor thermoelectric piece to the experimental plate. Further, the heat-conducting silicone grease layer refers to a heat-conducting silicone grease layer formed by coating heat silicone grease between the semiconductor thermoelectric piece and the experimental plate.

[0038] Further, the temperature control module further comprises a power supply, the power supply is a dual-channel power supply; the semiconductor thermoelectric piece and the thermocouple are both two; the temperature controller is a dual-channel temperature controller, the dual-channel temperature controller is connected to the two semiconductor thermoelectric pieces respectively to control the semiconductor thermoelectric pieces respectively; the temperature measuring instrument is a dual-channel temperature measuring instrument, the dual-channel temperature measuring instrument is connected to the two thermocouples respectively to detect the feedback temperature fed back by the two thermocouples respectively.

[0039] In combination with Figure 1 and Figure 2 As shown in the figures, the temperature gradient controllable micro-nanoparticle thermophoresis experimental system further comprises a microscopic imaging module having a collection part and a processing part connected to the collection part; the collection part is directly opposite to the center of the microchannel part to collect the movement process of the measured particles in the measured particle suspension; the processing part can process and analyze the movement process of the measured particles in the measured particle suspension collected by the collection part.

[0040] Specifically, the collection part comprises a fluorescence inverted microscope and a camera, and the processing part is a computer; the fluorescence inverted microscope is directly opposite to the center of the microchannel part; the camera is used to record the movement process of the measured particles in the measured particle suspension and form an image; the computer analyzes the image and outputs the migration direction, displacement curve and speed data of the measured particles.

[0041] Further, the microscopic imaging module further comprises a fluorescence excitation light source; green fluorescence modified polystyrene particles are added to the measured particle suspension to enable tracking of the movement state of the particles; when the movement process of the measured particles in the measured particle suspension is collected by the collection part, the fluorescence excitation light source is modulated to match the fluorescence channel of the measured particles in the measured particle suspension.

[0042] The following is a detailed description of the test process based on a dual-channel direct current power supply, a dual-channel temperature controller, two semiconductor thermoelectric pieces (3 cm * 3 cm), a stainless steel experimental plate with different sizes of microchannels (experimental plate size: 40 mm * 160 mm * 5 mm, microchannel size can be designed according to actual needs), a fluorescence inverted microscope, a camera, a computer, a dual-channel temperature measurement instrument, two temperature measuring thermocouples, a polystyrene experimental suspension, optical adhesive film, and heat-conducting silicone grease: Step 1: Rinse all microchannel areas on the experimental plate with anhydrous ethanol and ultrapure water in sequence, then wipe dry with a dust-free cloth to ensure that there is no dust, oil, or particle residue inside the channels.

[0043] Step 2: Take a certain volume of polystyrene fluorescent particle suspension (particle average diameter is 0.5 μm, 0.8 μm, 1 μm, or 2 μm), and use a microsyringe to inject the polystyrene fluorescent particle suspension into the test microchannel. Note that avoid air bubbles mixing into the test microchannel during injection, and ensure that the polystyrene fluorescent particle suspension is evenly distributed in the test microchannel and does not overflow the slot.

[0044] Step 3: Take a transparent optical sealing film and cover it evenly over the test microchannel; and press the film gently to ensure that the optical sealing film is tightly fitted to the edge of the experimental plate, avoiding evaporation of the polystyrene fluorescent particle suspension and imaging interference.

[0045] Step 4: Apply heat-conducting silicone grease between the contact surfaces of the two semiconductor thermoelectric pieces and the stainless steel experimental plate, ensuring uniformity. Place the semiconductor thermoelectric pieces tightly against the bottom of the experimental plate at both ends, and press them appropriately to ensure good heat conduction contact without gaps. In addition, connect the semiconductor thermoelectric pieces to the dual-channel temperature controller and the direct current stabilized power supply.

[0046] Step 5: Attach the temperature measuring ends of the two thermocouples to the temperature control areas at both ends of the experimental plate, and connect them to the dual-channel temperature measurement instrument. Turn on the dual-channel direct current power supply and the dual-channel temperature controller, and set the target temperature difference. At this time, note that different microchannels are arranged horizontally in the experimental plate, and the same thermal conditions (temperature gradient and average temperature) must be ensured for different microchannel experiments, so different cold and hot end temperatures must be set. See the specific details in Figure 3 .

[0047] Step 6: Observe the temperature feedback curve, wait for the system to output a linear temperature gradient, and maintain it for not less than 5 minutes to ensure uniform and stable thermal field.

[0048] Step 7: Combine Figure 4After the sample is placed, the whole experimental device is inverted with the optical adhesive film facing down and placed in the center of the inverted fluorescence microscope stage. The focal length and field position are adjusted so that the fluorescence microscope imaging area is directly opposite the center of the microchannel, avoiding the influence of the edge and wall. Then, turn on the fluorescence excitation light source and select the fluorescence channel that matches the particles to be tested. Then, set the fluorescence microscope magnification (10x) and light source intensity until the particle fluorescence is clearly visible. Then, adjust the focus layer to the center area of the channel to make the particle outline clear and the background clean.

[0049] Step 8: Set the camera acquisition frame rate (1 fps) and shooting time (set according to the channel width and particle speed, such as 20-500 s). Then, start image acquisition, record the whole process of particle movement, and save it to the computer in real time; then, import the image sequence into image processing software (such as ImageJ, TrackMate plug-in) after the acquisition is completed; finally, perform background subtraction and particle recognition to track the trajectory of each particle.

[0050] Step 9: Output the particle migration direction, displacement curve, and speed data for subsequent plotting or modeling analysis.

[0051] Step 10: After completing the single-channel experiment, clean the channel and replace the next group of channels (change the size or particle type) and repeat the above steps. Complete the thermophoresis experiment of multiple groups of channels according to the experimental plan.

[0052] In summary, first, the present application sets up symmetrically distributed semiconductor thermoelectric sheets and high thermal conductivity stainless steel experimental plates to form a stable temperature control platform, ensuring the formation of a continuous and controllable linear temperature gradient inside the microchannel, maintaining good stability in spatial distribution and time dimension, and providing clear driving force conditions for particle thermophoresis behavior. In addition, two semiconductor thermoelectric sheets are used for heating and cooling, respectively, and are tightly attached to the stainless steel experimental plate through heat-conducting silicone, forming a closed-loop control circuit with a thermocouple and a temperature controller, which can realize spatial stability, time stability, and linear adjustable temperature gradient output in the micron-scale experimental area.

[0053] Second, the microchannel structure is designed in groups, making it have multiple size parameters to choose from, supporting systematic research on structure size variables. The channel groups are arranged in the same thermal control area, with uniform temperature control conditions, which is conducive to efficient comparative experiments.

[0054] Second, the sample injection is simple and convenient, and the top sealing film structure meets the sealing and optical imaging requirements. The inverted fluorescence microscope imaging system can realize high-resolution visualization recording of the particle thermophoresis path with fluorescently labeled particles; the supporting image processing algorithm can accurately identify and extract parameters from the particle trajectory, outputting the motion speed, direction, and thermal response law.

[0055] Finally, the application has compact structure and simple operation, and is especially suitable for quantitative research on microscale thermophoresis physical mechanism in water phase or liquid phase medium, provides a key experimental platform for exploring thermophoresis law, constructing mathematical model and verifying physical mechanism, and has good scientific research applicability and development potential.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A temperature gradient controllable micro-nanoparticle thermophoresis experimental system, characterized in that, The temperature gradient controllable micro-nano particle thermophoresis experiment system comprises a micro-channel module, a temperature control module, and a microscopic imaging module. The micro-channel module comprises a bearing part and a micro-channel part arranged on the bearing part for loading a particle suspension to be tested. The micro-channel part has multiple groups of micro-channels with different size parameters. The temperature control module comprises a temperature control part, a temperature conduction part connected with the temperature control part and arranged on the bearing part at a first preset position, and a temperature detection part connected with the bearing part at a second preset position and forming a closed-loop temperature control with the temperature control part. The temperature control part controls the temperature conduction part to output a target temperature to the bearing part.

2. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 1, wherein, The temperature detection part can detect a feedback temperature of the bearing part. The temperature control part adjusts and controls the target temperature and the feedback temperature so that the micro-channel part can establish a stable thermal field.

3. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 2, wherein, The microscopic imaging module comprises a collection part and a processing part connected with the collection part. The collection part is arranged opposite to the center of the micro-channel part to collect the movement process of the particles to be tested in the particle suspension to be tested.

4. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 3, wherein, The processing part can process and analyze the movement process of the particles to be tested collected by the collection part. The bearing part is an experimental plate.

5. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 3, wherein, The experimental plate is a stainless steel experimental plate. The micro-channel part is arranged on the mounting position of the stainless steel experimental plate. The micro-channel module comprises multiple groups of micro-channel plates. The micro-channel plates are arranged in an array along a first direction. The temperature gradient controllable micro-nano particle thermophoresis experiment system further comprises an optical sealing film. The optical sealing film covers the experimental plate and is sealed to the experimental plate at a preset pressure to seal the micro-channel plate loading the particle suspension to be tested.

6. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 5, wherein, The temperature control part is a temperature controller. The temperature conduction part is a semiconductor thermoelectric sheet.

7. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 5, wherein, The temperature control part comprises a thermocouple and a temperature measuring instrument. The semiconductor thermoelectric sheet is multiple. The temperature controller controls the semiconductor thermoelectric sheet to output a target temperature to the experimental plate. The number of thermocouples is the same as the number of semiconductor thermoelectric sheets. The temperature measuring instrument is connected with the thermocouple. The temperature controller adjusts and controls the target temperature and the feedback temperature so that the micro-channel part can establish a stable thermal field. The temperature control module further comprises a heat-conducting silicone layer. The heat-conducting silicone layer is arranged between the semiconductor thermoelectric sheet and the experimental plate to reduce the contact thermal resistance between the semiconductor thermoelectric sheet and the experimental plate and to uniformly transmit the heat from the semiconductor thermoelectric sheet to the experimental plate. The temperature control module further comprises a power supply. The power supply is a double-channel power supply. The temperature controller is a double-channel temperature controller. The double-channel temperature controller is connected with two semiconductor thermoelectric sheets to control the semiconductor thermoelectric sheets respectively. The temperature measuring instrument is a double-channel temperature measuring instrument, which is connected with two thermocouples respectively and can detect feedback temperatures fed back by the two thermocouples respectively.

8. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 1, wherein, The collecting part comprises a fluorescence inverted microscope and a camera, and the processing part is a computer; The fluorescence inverted microscope is arranged at the center of the micro-channel part, and the camera is used to record the movement process of the particles in the particle suspension and form an image; The computer analyzes the image and outputs the migration direction, displacement curve and speed data of the particles.

9. The temperature-gradient-controllable micro-nanoparticle thermophoresis experimental system according to claim 8, wherein, The microscopic imaging module further comprises a fluorescence excitation light source; The particle suspension is added with green fluorescence modified polystyrene particles to track the movement state of the particles. When the movement process of the particles in the particle suspension is collected by the collecting part, the fluorescence excitation light source is modulated to match the fluorescence channel of the particles in the particle suspension.

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