阅读说明：本技术 一种流固两相输运中的微尺度颗粒直径测定的方法 (Method for measuring diameter of micro-scale particles in fluid-solid two-phase transportation ) 是由 胡箫 林培锋 朱祖超 林建忠 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种流固两相输运中的微尺度颗粒直径测定的方法。包括：配制多分散体系粘弹性流体；用压力源从入口端将最终的多分散体系粘弹性流体注入微通道内；调节微通道内流场的雷诺数和流体的弹性数,调节颗粒直径,使得颗粒在微通道出口端的中线位置形成颗粒链,通过颗粒链的结构和颗粒所在位置,实现不同颗粒直径的测定。本发明通过多分散体系颗粒在聚乙烯吡咯烷酮粘弹性流体管道中的迁移,使得不同直径的微尺度颗粒在微通道中形成颗粒直径沿流向依次增大的或者颗粒之间均匀稳定间距分布的颗粒链,从而对微颗粒的位置准确定位和直径的快速测量,极大地提高了流固两相输运中微颗粒定位和直径测量的精度和效率。(The invention discloses a method for measuring the diameter of micro-scale particles in fluid-solid two-phase transportation. The method comprises the following steps: preparing a multi-dispersion system viscoelastic fluid; injecting the final polydispersed viscoelastic fluid into the microchannel from the inlet end with a pressure source; adjusting the Reynolds number of a flow field in the microchannel and the elastic number of fluid, and adjusting the particle diameter to enable particles to form a particle chain at the center line position of the outlet end of the microchannel, and realizing the measurement of different particle diameters through the structure of the particle chain and the positions of the particles. According to the invention, through the migration of the particles of the polydisperse system in the polyvinylpyrrolidone viscoelastic fluid pipeline, the micro-scale particles with different diameters form a particle chain with the particle diameter sequentially increased along the flow direction or uniformly and stably distributed at intervals among the particles in the micro-channel, so that the position of the micro-particle is accurately positioned and the diameter of the micro-particle is rapidly measured, and the precision and the efficiency of positioning the micro-particle and measuring the diameter of the micro-particle in fluid-solid two-phase transportation are greatly improved.)

1. A method of micro-scale particle diameter determination in fluid-solid two-phase transport, the method comprising:

1) formulating polydisperse viscoelastic fluids

2) In a microchannel (4) of the microfluidic chip, the inlet end of the microchannel is connected with a pressure source (3), and the final multi-disperse-system viscoelastic fluid is injected into the microchannel from the inlet end by the pressure source (3), so that the final multi-disperse-system viscoelastic fluid is uniformly distributed at the inlet end of the microchannel;

3) forming a particle chain with the particle diameter which is sequentially increased along the flow direction at the center line position of the outlet end of the micro-channel or forming a particle chain with uniform and stable spacing distribution among particles by using a specific technical means, and further measuring the diameters of different particles;

the method is characterized by specifically comprising the following steps:

the preparation method of the multi-dispersion system viscoelastic fluid comprises the following steps: mixing deionized water and glycerol according to a mass fraction of 77: 23 to obtain a mixed solution of deionized water and glycerol, and then adding polyvinylpyrrolidone powder into the mixed solution of deionized water and glycerol to obtain a polyvinylpyrrolidone viscoelastic fluid (2); adding the particles (1) of the polydisperse system into the polyvinylpyrrolidone viscoelastic fluid (2) to ensure that the density of the polyvinylpyrrolidone viscoelastic fluid is the same as that of the particles to obtain the polydisperse system viscoelastic fluid, and finally adding the polyvinylpyrrolidone viscoelastic fluid (2) into the polydisperse system viscoelastic fluid to dilute the polyvide system viscoelastic fluid in concentration to obtain the final polydisperse system viscoelastic fluid;

the 3) is specifically as follows: adjusting the driving pressure of a pressure source (3) and the rheological property of polyvinylpyrrolidone viscoelastic fluid (2), so that the Reynolds number of a flow field in the microchannel is 1-50 and the elasticity number of the fluid is 1-3, adjusting the particle diameter in the viscoelastic fluid of a polydisperse system, and enabling all particles to move towards the downstream of the microchannel along the flow direction under the action of inertia caused by fixed driving pressure, the viscoelastic action of the viscoelastic fluid and the repulsive force when adjacent particles approach each other, so that particle chains with particle diameters sequentially increased along the flow direction are formed at the center line position of the outlet end of the microchannel of the particles, or particle chains with uniform and stable spacing distribution among the particles are formed, and the measurement of different particle diameters is realized through the structure of the particle chains and the positions of the particles.

2. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 1, wherein: the particles of the polydispersion system consist of solid spherical particles with micron scale, the diameters of the solid spherical particles are not uniform, and the diameter range of the particles is 10-30 mu m.

3. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 1, wherein: the microchannel is a straight channel with a square cross section.

4. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 1, wherein: the pressure source adopts a pressure pump or a syringe pump.

5. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 1, wherein: the particle chain with the particle diameter sequentially increasing along the flow direction is specifically as follows:

particle chains with uniform and stable spacing distribution among particles;

or adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a straight line;

or adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a broken line;

or the diameters of the particles are increased in turn along the flow direction, the connecting line of the circle centers of all the particles in the particle chain is a broken line, the adjacent particles in the former part are contacted with each other, the adjacent particles in the latter part are far away from the central line position of the outlet end of the microchannel, the adjacent particles in the latter part are not contacted with each other, and the change of the particle spacing is unstable.

6. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 5, wherein: when the particle diameters in the viscoelastic fluid of the polydisperse system are adjusted so that the blocking rates are the same, particle chains are formed in which the particles are uniformly and stably spaced.

7. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 5, wherein: when the diameters of the particles in the viscoelastic fluid of the polydisperse system are adjusted to ensure that the blocking rate of the particles with the largest diameters and the blocking rate of the particles with the smallest diameters are different by 0.02-0.06, a particle chain is formed, wherein the adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a straight line.

8. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 5, wherein: when the diameters of the particles in the viscoelastic fluid of the multi-dispersion system are adjusted, so that the blocking rate of the particles with the largest diameters and the blocking rate of the particles with the smallest diameters are different by 0.08-0.1, particle chains are formed, wherein the adjacent particles are in contact with each other, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chains is a broken line.

9. The method for diameter measurement of micro-scale particles in fluid-solid two-phase transport according to claim 5, wherein: when the particle diameter in the multi-dispersion system viscoelastic fluid is adjusted, so that the blocking rate of the particles with the largest diameter is different from that of the particles with the smallest diameter by 0.15-0.2, a particle chain with the diameters of the particles sequentially increasing along the flow direction is formed, the connecting line of the centers of the particles in the particle chain is a broken line, the adjacent particles in the former part are contacted with each other, the adjacent particles in the latter part are far away from the central line position of the outlet end of the microchannel, the adjacent particles in the latter part are not contacted with each other, and the change of the particle spacing is unstable.

Technical Field

The invention belongs to a particle diameter determination method in the field of solid-liquid two-phase flow in a microfluidic chip, and particularly relates to a method for determining the diameter of micro-scale particles in solid-liquid two-phase transportation.

Background

The particle migration in the non-Newtonian fluid is an important separation technology in a microfluidic analysis system, and the non-Newtonian fluid microfluidic chip technology can be used for rapidly and efficiently gathering particles and cell substances to the middle and the corners of the cross section of a pipeline so as to achieve the purpose of separating and screening the particles and the cell substances. However, in the micro-scale, the particle size is small, and the diameter measurement of the particles is difficult, so that the diameter measurement of the particles can be realized by adopting a complicated analysis means. How to simply, quickly and efficiently measure the diameter of the particles in a simple straight channel can improve the calibration accuracy and efficiency of the micro-scale particles. Therefore, in the research of the viscoelastic fluid of the micro-scale channel, the diameter of the micro-scale particles has important significance for improving the particle detection precision and the separation efficiency.

Disclosure of Invention

The invention aims to provide a method for measuring the diameter of micro-scale particles in fluid-solid two-phase transport, which is used for gathering multi-disperse system particles in a micro-fluidic chip to the central line of a micro-channel according to the viscoelastic action of a polyvinylpyrrolidone viscoelastic fluid and forming a particle chain structure mutually contacted with each other, wherein large particles are in front, small particles are behind, and the method can be used for rapidly measuring the diameter of the micro-scale particles and improving the precision and the efficiency of measuring the diameter of the micro-particles.

The purpose of the invention is realized by the following technical scheme:

the invention comprises the following steps:

1) preparing a multi-dispersion system viscoelastic fluid: mixing deionized water and glycerol according to a mass fraction of 77: 23 to obtain a mixed solution of deionized water and glycerol, and then adding polyvinylpyrrolidone powder into the mixed solution of deionized water and glycerol to obtain polyvinylpyrrolidone viscoelastic fluid; adding particles of a polydisperse system into the polyvinylpyrrolidone viscoelastic fluid to ensure that the density of the polyvinylpyrrolidone viscoelastic fluid is the same as that of the particles to obtain the polydisperse system viscoelastic fluid, and finally adding the polyvinylpyrrolidone viscoelastic fluid into the polydisperse system viscoelastic fluid to dilute the polyvinylpyrrolidone viscoelastic fluid in concentration to obtain the final polydisperse system viscoelastic fluid;

2) in a microchannel of the micro-fluidic chip, an inlet end of the microchannel is connected with a pressure source, and the final multi-disperse system viscoelastic fluid is injected into the microchannel from the inlet end by the pressure source, so that the final multi-disperse system viscoelastic fluid is uniformly distributed at the inlet end of the microchannel;

3) adjusting the driving pressure of a pressure source and the rheological property of the polyvinylpyrrolidone viscoelastic fluid to ensure that the Reynolds number Re of the flow field in the microchannel is 1-50(Re is 2 rho Q/(mu)₀(W + H), ρ is the density of the viscoelastic fluid, Q is the fluid flow rate at pressure actuation, H, W is the height and width of the microchannel, μ₀Viscosity of viscoelastic fluid) and the elastic number Wi of the fluid, i.e. the weissenberg number of the fluid, of 1 to 3, Wi being 2 λ Q/(HW)²) And λ is the relaxation time of the viscoelastic fluid. The particle diameter in the viscoelastic fluid of the polydisperse system is adjusted, all particles move towards the downstream of the microchannel along the flow direction under the action of inertia caused by fixed driving pressure, the viscoelastic action of the viscoelastic fluid and the repulsive force when adjacent particles are close to each other, so that particle chains with particle diameters sequentially increased along the flow direction are formed at the center line position of the outlet end of the microchannel, namely large particles are in front of small particles, or particle chains with uniformly and stably distributed intervals among the particles are formed, and the measurement of different particle diameters is realized through the structure of the particle chains and the positions of the particles.

The particles of the polydispersion system consist of solid spherical particles with micron scale, the diameters of the solid spherical particles are not uniform, and the diameter range of the particles is 10-30 mu m.

The microchannel is a straight channel with a square cross section.

The pressure source adopts a pressure pump or a syringe pump.

The particle chain with the particle diameter sequentially increasing along the flow direction is specifically as follows:

particle chains with uniform and stable spacing distribution among particles;

or adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a straight line;

or adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a broken line;

or the diameters of the particles are increased in turn along the flow direction, the connecting line of the circle centers of all the particles in the particle chain is a broken line, adjacent particles in the former part are contacted with each other, namely the large particles in the former part are contacted with each other, the adjacent particles in the latter part are far away from the central line position of the outlet end of the microchannel, the adjacent particles in the latter part are not contacted with each other, the change of the particle distance is unstable, namely the distance between the small particles in the latter part is not stable any more.

When the particle diameters in the viscoelastic fluid of the polydisperse system are adjusted so that the blocking rates k (k ═ D/H, D is the diameter of the particles) are the same, particle chains are formed in which the distance distribution between the particles is uniform and stable.

When the diameters of the particles in the viscoelastic fluid of the polydisperse system are adjusted to ensure that the blocking rate of the particles with the largest diameters and the blocking rate of the particles with the smallest diameters are different by 0.02-0.06, a particle chain is formed, wherein the adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chain is a straight line.

When the diameters of the particles in the viscoelastic fluid of the multi-dispersion system are adjusted, so that the blocking rate of the particles with the largest diameters and the blocking rate of the particles with the smallest diameters are different by 0.08-0.1, particle chains are formed, wherein the adjacent particles are in contact with each other, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of all the particles in the particle chains is a broken line.

When the particle diameters in the multi-dispersion system viscoelastic fluid are adjusted, so that the blocking rate of the particles with the largest diameters and the blocking rate of the particles with the smallest diameters are different by 0.15-0.2, a particle chain with the diameters sequentially increasing along the flow direction is formed, the connecting line of the circle centers of all the particles in the particle chain is a broken line, adjacent particles in the former part are in contact with each other, namely the large particles in the former part are in contact with each other, adjacent particles in the latter part are far away from the middle line position of the outlet end of the microchannel, the adjacent particles in the latter part are not in contact with each other, the change of the particle spacing is unstable, namely the spacing between the small particles in the latter part is not stable any more.

Based on the technical scheme, the invention has the following beneficial effects:

the whole micro-fluidic chip has a simple structure, and micro-scale solid particles with different diameters can move to a specified position in a straight channel of the simple micro-fluidic chip by controlling the rheological property, driving pressure and solid particle diameter of fluid through the migration of multi-dispersion system particles in a polyvinylpyrrolidone viscoelastic fluid square channel without other external force conditions. Particle chains with particles separated from each other and uniformly spaced are formed in the micro-channels, or particle chain structures which are mutually contacted with each other are formed in a self-organizing way, and the particle diameters of micro-particles in the particle chains are decreased, namely the chain structures with large particles at the front and small particles at the back are formed. The formed particle structure can be stably kept in the channel centerline and is not influenced by the wall surface. By comparing different particle structures formed in the channel, the diameters of particles can be quickly obtained, the aims of accurately positioning the positions of the microparticles and quickly measuring the diameters are fulfilled, the precision and the efficiency of microparticle positioning and diameter measurement in fluid-solid two-phase transportation are greatly improved, and a simple and effective method is provided for realizing efficient counting and separation on a microfluidic chip.

Drawings

Embodiments of the invention are described in further detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic representation of the movement of polydisperse particles in a microchannel to form particle chains in which the particles contact each other;

in the figure: 1. (ii) a polydisperse particle; 2. a polyvinylpyrrolidone viscoelastic fluid; 3. a pressure source; 4. a microchannel of the microfluidic chip; 5. a particle chain with large particles in front and small particles in back.

FIG. 2 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.3, 0.3, 0.3, and 0.3, respectively;

FIG. 3 is a graph showing the process of forming particle chains in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.295, 0.29, 0.285, and 0.28, respectively;

FIG. 4 is a graph showing the process of forming particle chains in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.29, 0.28, 0.27, and 0.26, respectively;

FIG. 5 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.285, 0.27, 0.255, and 0.24, respectively;

FIG. 6 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.28, 0.26, 0.24, and 0.22, respectively;

FIG. 7 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively;

FIG. 8 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.25, 0.20, 0.175, and 0.15, respectively;

FIG. 9 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.25, 0.20, 0.15, and 0.10, respectively;

FIG. 10 shows the process of forming particle chains in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 50, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively;

FIG. 11 shows the process of forming particle chains in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 3, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively;

FIG. 12 shows the process of forming particle chains in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 0, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively;

FIG. 13 shows the process of particle chain formation in a polyvinylpyrrolidone viscoelastic fluid when the Reynolds number of the flow field is 1, the elasticity number of the fluid is 0.01, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively;

fig. 14 shows the process of forming particle chains in the polyvinylpyrrolidone viscoelastic fluid when the reynolds number of the flow field is 0.01, the elasticity number of the fluid is 1, and the blocking rates of the particles are 0.3, 0.25, 0.24, 0.22, and 0.20, respectively.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

The invention provides a method for measuring the diameter of microparticles in fluid-solid two-phase transportation, which takes solid-liquid two-phase flow in a straight channel in a microfluidic chip as a research object, and by adjusting the viscoelastic rheological property and the diameter of solid particles of a fluid, micro-sized polydisperse solid spherical particles can automatically move to the middle of the channel under the inertia action and the elastic action of the fluid in the microchannel without other external force, and particle chains with uniform intervals or long straight particle chains with particles mutually contacted are formed in the middle of the channel, wherein large particles are arranged at the front section of the particle chains, and small particles are arranged at the tail part of the particle chains. And comparing the change of the distance between two adjacent particles along with the displacement of the solid particles along the flow direction, and comparing particle chains formed after the particles with different diameters in the micro-channel are transferred to the central line of the pipeline, so that different situations of contact and separation of the solid particles are obtained, and the aim of quickly screening the diameters of the micro-scale particles is fulfilled. The invention can improve the precision and efficiency of the diameter measurement of the microparticles in the fluid-solid two-phase transportation, and is beneficial to the cell detector to detect and measure the cells and the particles.

The method comprises the following steps:

1) preparing a multi-dispersion system viscoelastic fluid: mixing deionized water and glycerol according to a mass fraction of 77: 23 to obtain a mixture of deionized water and glycerol, and adding polyethyleneAdding the vinylpyrrolidone powder into a mixed solution of deionized water and glycerol, wherein in the specific implementation, the molecular weight of the polyvinylpyrrolidone powder is Mw (360 kDa), and thus obtaining a polyvinylpyrrolidone viscoelastic fluid 2 with the concentration of 5%; adding the polydisperse system particles 1 into the polyvinylpyrrolidone viscoelastic fluid 2 to ensure that the density of the polyvinylpyrrolidone viscoelastic fluid is the same as that of the particles, and the density of the polyvinylpyrrolidone viscoelastic fluid and the density of the particles are both 1.05g/cm³Obtaining a polydisperse system viscoelastic fluid which is a neutral suspension solution, and finally adding polyvinylpyrrolidone viscoelastic fluid 2 into the polydisperse system viscoelastic fluid for concentration dilution to obtain a final polydisperse system viscoelastic fluid with the concentration of 0.35%; wherein the particles of the polydispersion system consist of solid spherical particles with micron scale, the diameters of the solid spherical particles are not uniform, and the diameter range of the particles is 10-30 mu m.

2) In the microchannel 4 of the microfluidic chip, the microchannel is a straight channel with a square cross section, i.e., H ═ W, which is 100 μm in specific implementation. The inlet end of the microchannel is connected with a pressure source 3, and the pressure source adopts a pressure pump or a syringe pump. Injecting the final polydisperse viscoelastic fluid into the microchannel from the inlet end with a pressure source 3 such that the final polydisperse viscoelastic fluid is uniformly distributed at the inlet end of the microchannel;

3) the driving pressure of the pressure source 3 and the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 are adjusted so that the reynolds number Re of the flow field in the microchannel is 1 to 50(Re 2 ρ Q/(μ ═ Q)₀(W + H), ρ is the density of the viscoelastic fluid, Q is the fluid flow rate at pressure actuation, H, W is the height and width of the microchannel, μ₀Viscosity of viscoelastic fluid) and the elastic number Wi of the fluid, i.e. the weissenberg number of the fluid, of 1 to 3, Wi being 2 λ Q/(HW)²) And λ is the relaxation time of the viscoelastic fluid. In specific implementation, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 is adjusted by adjusting the concentration of the polyvinylpyrrolidone powder in the polyvinylpyrrolidone viscoelastic fluid 2, and the larger the concentration is, the longer the relaxation time of the viscoelastic fluid is, the larger the elasticity number of the viscoelastic fluid is. Adjusting the particle diameter of the viscoelastic fluid in a polydisperse system, all particles being immobilizedThe inertia caused by the fixed driving pressure, the viscoelasticity of the viscoelastic fluid and the repulsion when the adjacent particles approach each other move to the downstream of the micro-channel along the flow direction, wherein the inertia caused by the fixed driving pressure of the particles is determined by the Reynolds number of the flow field, and the viscoelasticity of the fluid is determined by the elasticity number of the fluid, so that particle chains with the particle diameters sequentially increased along the flow direction are formed at the center line position of the outlet end of the micro-channel by the particles, namely large particles are in front of small particles, and the measurement of different particle diameters is realized through the structure of the particle chains and the positions of the particles.

The specific embodiment of the invention is as follows:

in the specific implementation, through a virtual area method, direct numerical simulation calculates that in a micro-channel 4 of a micro-fluidic chip, polyvinylpyrrolidone viscoelastic fluid 2 is filled in the micro-channel 4 of the micro-fluidic chip through a driving pressure source 3, the density of polydisperse system particles 1 is the same as that of liquid phase polyvinylpyrrolidone viscoelastic fluid, initial polydisperse system particles are randomly distributed in the micro-channel 4 of the micro-fluidic chip, the polydisperse system particles 1 are injected into the micro-channel 4 of the micro-fluidic chip under the action of the driving pressure source 3 at an inlet section of the micro-channel 4 of the micro-fluidic chip, under the action of a given driving pressure source 3, inertial force caused by the driving pressure source 3, elastic force of the polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, the polydisperse system particles 1 all migrate to the middle of the micro-channel 4 of the micro-fluidic chip, and form a particle chain 5 with large particles in front and small particles in back.

As shown in fig. 1, a schematic diagram of the movement of polydisperse particles in a microchannel to form particle chains with particles in contact with each other. The width and the height of the section of the micro-channel 4 of the micro-fluidic chip are both H, and the length of the micro-channel 4 of the micro-fluidic chip is L. The fluid in the micro-channel 4 of the micro-fluidic chip is polyvinylpyrrolidone viscoelastic fluid 2, a driving pressure source 3 is given to the inlet of the micro-channel 4 of the micro-fluidic chip to enable the polyvinylpyrrolidone viscoelastic fluid 2 and the polydisperse system particles 1 to move, and the polydisperse system particles 1 are randomly distributed in the micro-channel 4 of the micro-fluidic chip at the initial moment. When the polydisperse particles 1 move downstream under the action of inertial force caused by the driving pressure source 3, elastic force of the polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, particle chains 5 with large particles in front and small particles in back are formed. The particle chain 5 with large particles in front and small particles in back is stable, and the position of the particle chain is fixed on the central line of the micro-channel 4 of the micro-fluidic chip, which is beneficial to observing the diameter and position of the particles 1 of the polydisperse system.

Taking the nondimensional movement length x/H of the flowing direction of the particles 1 of the polydispersion system and the surface distance d of the nondimensional particles of two adjacent particles 1 of the polydispersion system in numerical simulation calculation_sThe particle diameter of the particle chain 5 with large particles in front and small particles in back formed by the micro-channel 4 of the micro-fluidic chip is named as D from right to left in sequence₁,D₂,D₃,D₄,D₅Polydisperse particles 1 are designated P from right to left in that order₁，P₂，P₃，P₄，P₅Therefore, the change in the inter-particle distance between the particle chain 5 in which the large particle is formed before and the small particle is formed after the particles 1 forming the polydispersion move in the microchannel 4 of the microfluidic chip is represented as P_D1-P_D2，P_D2-P_D3，P_D3-P_D4，P_D4-P_D5。

Detailed description of the preferred embodiment 1

Specifically, the result of direct numerical simulation by the virtual area method is shown in fig. 2, and during calculation, the pressure source 3 is adjusted to make the reynolds number (Re) of the flow field 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 is adjusted to make the weisen bog number (Wi) of the flow field 1, and the blocking rate of the polydisperse particles 1 is adjusted to 0.3. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when the polydisperse particles move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles are close to each other, the polydisperse particles all migrate to the central line position of the outlet end of the microchannel 4 of the microfluidic chip, the distance between the adjacent particles in the movement process of the particles is shown in fig. 2, and the polydisperse particles 1 are distributed as shown in an inset of fig. 2, so that particle chains with uniform and stable distance distribution among the particles are formed.

Specific example 2

Specifically, the result of direct numerical simulation by the virtual area method is shown in fig. 3, where the pressure source 3 is adjusted during calculation so that the reynolds number (Re) of the flow field is 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 is adjusted so that the weisen bog number (Wi) of the flow field is 1, and the blocking rates of the polydisperse particles 1 are adjusted to 0.3, 0.295, 0.29, 0.285, and 0.28, respectively. Initial polydisperse system particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse system particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse system particles 1 all migrate to the central line position of the outlet end of the micro-channel 4 of the micro-fluidic chip, the distance between adjacent particles in the movement process of the particles is shown in figure 3, the distribution of polydisperse system particles 1 is shown in the inset of figure 3, a particle chain with uniform and stable distance cannot be formed, a particle chain 5 with large particles in front and small particles in back is formed, the adjacent particles are mutually contacted, and the connecting line of the circle centers of all the particles in the particle chain is a straight line.

Specific example 3

Specifically, as shown in fig. 4, the results of direct numerical simulation by the virtual area method were obtained by adjusting the pressure source 3 to 1 reynolds number (Re) of the flow field, adjusting the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to 1 weisen bog number (Wi) of the flow field, and adjusting the blocking rates of the polydisperse particles 1 to 0.3, 0.29, 0.28, 0.27, and 0.26. Initial polydisperse system particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse system particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse system particles 1 all migrate to the central line position of the outlet end of the micro-channel 4 of the micro-fluidic chip, the distance between adjacent particles in the movement process of polydisperse system particles 1 is shown as figure 4, the distribution of polydisperse system particles 1 is shown as an inset of figure 4, a particle chain with uniform and stable distance cannot be formed, a particle chain 5 with large particles in front and small particles in back is still formed, adjacent particles are mutually contacted, and the connecting line of the circle centers of all particles in the particle chain is a straight line.

Specific example 4

Specifically, the result of direct numerical simulation by the virtual area method is shown in fig. 5, where the pressure source 3 is adjusted to set the reynolds number (Re) of the flow field to 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 is adjusted to set the weisen bog number (Wi) of the flow field to 1, and the blocking rates of the polydisperse particles 1 are adjusted to 0.3, 0.285, 0.27, 0.255, and 0.24, respectively, in the calculation. Initial polydisperse system particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse system particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse system particles 1 all migrate to the central line position of the outlet end of the micro-channel 4 of the micro-fluidic chip, the distance between adjacent particles in the movement process of polydisperse system particles 1 is shown in figure 5, the distribution of polydisperse system particles 1 is shown in the inset of figure 5, particle chains with uniform and stable distances cannot be formed, particle chains 5 with large particles in front and small particles in back are still formed, adjacent particles are mutually contacted, and the connecting line of the circle centers of all particles in the particle chains is a straight line.

Specific example 5

Specifically, as shown in fig. 6, the result of direct numerical simulation by the virtual area method is obtained by adjusting the pressure source 3 to make the reynolds number (Re) of the flow field 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to make the weisen bog number (Wi) of the flow field 1, and the blocking rates of the polydisperse particles 1 to 0.3, 0.28, 0.26, 0.24, and 0.22. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse particles 1 all migrate to the center line position of the outlet end of the microchannel 4 of the microfluidic chip, the distance between adjacent particles in the movement process of polydisperse particles 1 is shown in fig. 6, the distribution of polydisperse particles 1 is shown in the inset of fig. 6, a particle chain with uniform and stable spacing cannot be formed, a particle chain 5 with large particles in front and small particles in back is still formed, but the formed particle chain 5 with large particles in front and small particles in back slightly begins to bend, namely, the connecting line of the circle centers of each particle in the particle chain is a broken line.

Specific example 6

Specifically, as shown in fig. 7, the result of direct numerical simulation by the virtual area method is obtained by adjusting the pressure source 3 to make the reynolds number (Re) of the flow field 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to make the weisen bog number (Wi) of the flow field 1, and the blocking rates of the polydisperse particles 1 to 0.3, 0.25, 0.24, 0.22, and 0.20. Initial polydisperse particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse particles 1 all migrate to the center line position of the outlet end of the micro-channel 4 of the micro-fluidic chip, the distance between adjacent particles in the movement process of polydisperse particles 1 is shown in fig. 7, the distribution of polydisperse particles 1 is shown in the inset of fig. 7, a particle chain with uniform and stable distance cannot be formed, a particle chain 5 with large particles in front and small particles in back is still formed, and the bending degree of the particle chain 5 with large particles in front and small particles in back is increased.

Specific example 7

Specifically, as shown in fig. 8, the result of direct numerical simulation by the virtual area method is obtained by adjusting the pressure source 3 to 1 reynolds number (Re) of the flow field, adjusting the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to 1 weisen bog number (Wi) of the flow field, and adjusting the blocking rate of the polydisperse particles 1 to 0.3, 0.25, 0.20, 0.175, and 0.15. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse particles 1 all migrate to the central line position of the outlet end of the microchannel 4 of the microfluidic chip, the distance between adjacent particles in the movement process of polydisperse particles 1 is shown in fig. 8, the distribution of polydisperse particles 1 is shown in the inset diagram of fig. 8, a particle chain with uniform and stable distance cannot be formed, and a particle chain 5 with large particles in front and small particles in back is still formed, but adjacent particles with blocking ratios of 0.3, 0.25, 0.20 and 0.175 are mutually contacted, particles with blocking ratio of 0.15 are far away from the central line of the microchannel 4 of the microfluidic chip, the particles are separated from the polyvinylpyrrolidone viscoelastic fluid 2, particle chains which are mutually contacted are not formed any more, and the change of the particle distance is unstable.

Specific example 8

Specifically, as shown in fig. 9, the result of direct numerical simulation by the virtual area method is obtained by adjusting the pressure source 3 to 1 reynolds number (Re) of the flow field, adjusting the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to 1 weisen bog number (Wi) of the flow field, and adjusting the blocking rate of the polydisperse particles 1 to 0.3, 0.25, 0.20, 0.15, and 0.10. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3 and elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse particles 1 all migrate to the midline position of the outlet end of the microchannel 4 of the microfluidic chip, the distance between adjacent particles in the movement process of polydisperse particles 1 is shown in figure 9, the distribution of polydisperse particles 1 is shown in the inset of figure 9, two adjacent polydisperse particles 1 cannot form a particle chain with uniform and stable distance, and still form a particle chain 5 with large particles at the front and small particles at the back, but particles with blocking rates of 0.3, 0.25 and 0.20 are mutually contacted, particles with blocking rates of 0.15 and 0.10 are far away from the central line of the microchannel 4 of the microfluidic chip, the particles are separated from the polyvinylpyrrolidone viscoelastic fluid 2, particle chains which are mutually contacted are not formed any more, and the change of the particle distance is unstable.

Specific example 9

Specifically, as shown in fig. 10, the results of direct numerical simulation by the virtual area method were obtained by adjusting the pressure source 3 to 50 the reynolds number (Re) of the flow field, adjusting the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to 1 the weisen bog number (Wi) of the flow field, and adjusting the blocking rates of the polydisperse particles 1 to 0.3, 0.25, 0.24, 0.22, and 0.20. The initial polydisperse particles are randomly distributed in the micro-channels 4 of the microfluidic chip, the inertial force of the polydisperse particles 1 caused by the driving pressure source 3, and when the downstream is moved by the elastic force action of the polyvinylpyrrolidone viscoelastic fluid 2 and the repulsive force action when adjacent particles approach each other, the polydisperse particles 1 all migrate to the midline of the outlet end of the microchannel 4 of the microfluidic chip, the spacing between adjacent particles during the movement of the polydisperse particles 1 is shown in figure 10, due to the strong inertia force caused by the driving pressure source 3, the variation amplitude of the distance between adjacent particles is increased, the distribution of the polydisperse particles 1 is as shown in the inset of fig. 10, a particle chain with uniform and stable distance cannot be formed, however, the particle chains 5 with large particles in front and small particles in back are still formed, and the bending degree of the particle chains 5 with large particles in front and small particles in back is further increased.

Detailed description of example 10

Specifically, as shown in fig. 11, the results of direct numerical simulation by the virtual area method were obtained by adjusting the pressure source 3 to 1 reynolds number (Re) of the flow field, adjusting the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 to 3 weissenberg number (Wi) of the flow field, and adjusting the blocking rates of the polydisperse particles 1 to 0.3, 0.25, 0.24, 0.22, and 0.20. Initial polydisperse particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles approach each other, polydisperse particles 1 all migrate to the center line position of the outlet end of the micro-channel 4 of the micro-fluidic chip, the distance between adjacent particles in the movement process of polydisperse particles 1 is shown in fig. 11, the distribution of polydisperse particles 1 is shown in the inset of fig. 11, a particle chain with uniform and stable distance cannot be formed, a particle chain 5 with large particles in front and small particles in back is still formed, and the bending degree of the particle chain 5 with large particles in front and small particles in back is increased.

Specific example 11

Specifically, the result of direct numerical simulation by the virtual area method is shown in fig. 12, where the pressure source 3 is adjusted during calculation so that the reynolds number (Re) of the flow field is 1, the rheological property of the polyvinylpyrrolidone viscoelastic fluid 2 is adjusted so that the weisen bog number (Wi) of the flow field is 0, indicating that the polyvinylpyrrolidone viscoelastic fluid 2 is not acted by an elastic force, and the blocking rates of the polydisperse particles 1 are adjusted to be 0.3, 0.25, 0.24, 0.22, and 0.20. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3 and repulsion force when adjacent particles approach each other, polydisperse particles 1 all migrate to the wall position of the outlet end of the microchannel 4 of the microfluidic chip, the distance between adjacent particles in the movement process of the polydisperse particles 1 is shown in fig. 12, the distribution of the polydisperse particles 1 is shown in the inset of fig. 12, a particle chain with uniform and stable distance is formed, but a particle chain 5 with large particles in front and small particles in back cannot be formed.

Detailed description of example 12

Specifically, as shown in fig. 13, the results of direct numerical simulation by the virtual area method were obtained by adjusting the pressure source 3 to 1 reynolds number (Re) of the flow field, and the rheological properties of the polyvinylpyrrolidone viscoelastic fluid 2 to 0.01 weissenberg number (Wi) of the flow field, and the blocking rates of the polydisperse particles 1 to 0.3, 0.25, 0.24, 0.22, and 0.20, respectively. Initial polydisperse system particles are randomly distributed in a micro-channel 4 of a micro-fluidic chip, when polydisperse system particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles are close to each other, polydisperse system particles 1 cannot migrate to the central line position of the outlet end of the micro-channel 4 of the micro-fluidic chip but are distributed near the central line of the micro-channel 4 of the micro-fluidic chip because the elastic force of the polyvinylpyrrolidone viscoelastic fluid 2 is weaker, polydisperse system particles 1 are distributed as shown in fig. 13, particle chains with uniform and stable intervals cannot be formed, and particle chains 5 with large particles in front and small particles in back do not appear.

Specific example 13

Specifically, as shown in fig. 14, the results of direct numerical simulation by the virtual area method were obtained by adjusting the pressure source 3 to set the reynolds number (Re) of the flow field to 0.01, and the rheological properties of the polyvinylpyrrolidone viscoelastic fluid 2 to set the weisen bog number (Wi) of the flow field to 1, and the blocking rates of the polydisperse particles 1 to 0.3, 0.25, 0.24, 0.22, and 0.20. Initial polydisperse particles are randomly distributed in a microchannel 4 of a microfluidic chip, when polydisperse particles 1 move downstream under the action of inertia force caused by a driving pressure source 3, elastic force of polyvinylpyrrolidone viscoelastic fluid 2 and repulsive force when adjacent particles are close to each other, only polydisperse particles 1 with larger diameter migrate to the center line position of the outlet end of the microchannel 4 of the microfluidic chip due to weaker inertia force caused by the driving pressure source 3, polydisperse particles 1 with smaller diameter are not stabilized at the center line position of the outlet end of the microchannel 4 of the microfluidic chip, the polydisperse particles 1 are distributed as shown in fig. 14, particle chains with uniform and stable intervals cannot be formed, only particle chains 5 with short large particles before and small particles after are formed, and the polydisperse particles 1 are dispersed near the center line position of the outlet end of the microchannel 4 of the microfluidic chip along with the single polydisperse particles 1, the degree of bending of the particle chain 5 is increased in which large particles are in front and small particles are in back.

According to the specific embodiment, when the reynolds number of the flow field in the microchannel is less than 1 by adjusting the driving pressure of the pressure source, a particle chain with uniform and stable spacing distribution among particles cannot be formed, and small-diameter multi-dispersion particles cannot migrate to the centerline position of the microchannel. When the Reynolds number is 50, particle chains with uniform and stable spacing distribution among particles can be formed, but the variation range of the spacing among the particle chains is increased, and the particle chains with uniform and stable spacing distribution among the particles can not be formed by continuously increasing the Reynolds number. When the Reynolds number is 1-50, a particle chain is formed, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the centers of the particles in the particle chain is a broken line.

And adjusting the elasticity number of the fluid, wherein when the elasticity number of the fluid in the microchannel is less than 1, a particle chain with uniform and stable spacing distribution among particles cannot be formed, and multi-dispersion volume particles cannot migrate to the centerline position of the microchannel. When the elasticity number is increased to 1-3, a particle chain is formed, wherein adjacent particles are mutually contacted, the diameters of the particles are sequentially increased along the flow direction, and the connecting line of the circle centers of the particles in the particle chain is a broken line.