A method for controlling particle motion using eccentric cylindrical flow

Abstract

The present invention discloses a method for controlling the motion of particles using an eccentric cylindrical flow; the controlled particles are located in a flow field between an inner cylinder and an outer cylinder whose axes are parallel and coaxial. Given the radius ratio of the inner and outer cylinders, the present invention continuously adjusts the direction and size of the flow field velocity at the point where the particles are located by changing the angular velocity and the axis spacing of the inner and outer cylinders in real time, so that the controlled particles move in a set direction, thereby achieving the purpose of controlling the particle motion trajectory. Compared with the currently known fluid dynamic particle manipulation methods, this method has the characteristics of a large particle motion range, a simple control method, and a small flow field force, and can provide a new experimental means for cutting-edge scientific fields such as microbial analysis, disease diagnosis, and drug transportation.

Description

Technical Field

[0001] The invention relates to a method for controlling particle motion, and in particular to a method for controlling particle motion by using an eccentric cylindrical flow. Background Art

[0002] In recent years, the continuous development of measurement and analysis technology has made it possible to analyze and study the physical, chemical, and biological properties of individual micro-nano particles. Such particles include: individual magnetic or dielectric particles, individual cells, and even individual DNA molecules. Generally speaking, some particles need to be placed in a liquid environment for observation. Because the particles are too small, in order to overcome the Brownian motion effect, they must be accurately captured or manipulated to ensure that they are always in the effective analysis field. Therefore, particle manipulation technology in fluids is a key technology in particle analysis technology, and has broad application prospects in cutting-edge scientific fields such as microbial analysis, disease diagnosis, drug transportation, and surface self-cleaning.

[0003] Currently, the more mature methods for controlling fluid-dynamically driven particles are all based on planar stagnation point flow. However, this method is difficult to control particles because the flow potential well at the stagnation point is inherently unstable. At the same time, the force exerted by the fluid at the stagnation point on the particles is also large, making it unsuitable for application to flexible particles, especially living particles. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies of the above-mentioned prior art and provide a method for controlling particle motion using an eccentric cylindrical flow. In view of the existing actual situation and the demand for particle manipulation, the method of controlling particle motion using an eccentric cylindrical flow of the present invention can achieve gentle, precise and large-scale control of particles in the flow field.

[0005] The present invention is achieved through the following technical solutions:

[0006] 1. A method for controlling particle motion using an eccentric cylindrical flow, characterized in that it comprises the following steps:

[0007] Step 1: Place the controlled particle 1 in the flow field between the inner cylinder 3 and the outer cylinder 2 whose axes are parallel and coaxial; the flow field serves as the control area of ​​the controlled particle 1;

[0008] The real-time motion data of the controlled particle 1 in the flow field is obtained through the imaging device 4; the real-time motion data refers to the real-time position of the controlled particle 1 in the flow field; the motion position of the controlled particle 1 in the flow field can be controlled by changing the angular velocity and the axis distance between the inner cylinder 3 and the outer cylinder 2 in real time.

[0009] Step 2: Based on the real-time dynamic data obtained in step 1, a rectangular coordinate system with the center of the inner cylinder 3 as the origin is established, and the current coordinates of the controlled particle 1 are used as the starting point of the trajectory. Any curve is selected in the control area of ​​the controlled particle 1 as the control trajectory of the particle;

[0010] Step 3: Select appropriate time intervals according to accuracy requirements to discretize the entire trajectory motion time and determine the velocity direction and magnitude of the trajectory within each time interval;

[0011] Step 4: The velocity direction of the controlled particle 1 is considered to be consistent with the velocity direction of the flow field at this point; according to the velocity direction and magnitude obtained in step 3, the angular velocity ω of the inner cylinder 3 corresponding to each time interval is obtained by using the finite difference method combined with the analytical solution of the eccentric cylindrical flow. i , angular velocity ω of outer cylinder 2 o The data of the axial distance (eccentricity) e between the inner and outer cylinders.

[0012] Step 5: According to the data obtained in step 4, adjust the angular velocity w of the inner tube 3 in real time i , the angular velocity w of the outer cylinder 2 o The axial distance (eccentricity) e between the inner and outer cylinders makes the controlled particle 1 move along the set direction, and finally realizes the movement of the controlled particle 1 in the flow field along the set trajectory.

[0013] The radius ratio between the inner cylinder 3 and the outer cylinder 2 is adjustable, that is, it is achieved by replacing the inner cylinder 3 and the outer cylinder 2 with different radii.

[0014] The angular velocity of the inner cylinder 3 and the outer cylinder 2 can be adjusted in real time, or the angular velocity ratio of the inner cylinder 3 and the outer cylinder 2 can be adjusted in real time.

[0015] The axial distance between the inner cylinder 3 and the outer cylinder 2 can be adjusted in real time, or the eccentricity ratio between the inner cylinder 3 and the outer cylinder 2 can be adjusted in real time.

[0016] The controlled particles 1 are polymer particles, drug-loaded particles, cells, micro-nano devices, droplets, microbubbles or dynamic organisms.

[0017] The geometric shapes of the contours of the inner cylinder 3 and the outer cylinder 2 are circular, elliptical or rectangular.

[0018] The flow field is filled with PDMS (polydimethylsiloxane) solution, and other types of solutions can be selected according to actual application requirements.

[0019] Compared with the prior art, the present invention has the following advantages and effects:

[0020] (1) The eccentric cylindrical flow field has a large size, so the movement range of the particles is also large.

[0021] (2) When the radius of the inner and outer cylinders is determined, this method can control the motion trajectory of the particles by only controlling the angular velocity and the axis distance (eccentricity) of the inner and outer cylinders. The control method is simple.

[0022] (3) In this method, the fluid exerts little force on the particles, which will not cause damage to particles with life characteristics, nor will it cause excessive deformation or rupture of the particles.

[0023] (4) The device required for this method has a simple structure and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of controlling particle motion using eccentric cylindrical flow in the present invention;

[0025] Figure 2 It is a schematic diagram of a device for controlling particle motion using an eccentric cylindrical flow according to the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments.

[0027] like Figure 1 , Figure 2 As shown, the present invention uses the use of an eccentric cylindrical flow to manipulate the movement of a controlled particle 1 in polydimethylsiloxane (PDMS) as an example; the controlled particle 1 is a nylon particle.

[0028] The nylon particles are located in the flow field between the inner cylinder 3 and the outer cylinder 2 whose axes are parallel and not coaxial.

[0029] The radius R of the inner cylinder 3 i The radius R of the outer cylinder 2 o It can be changed by replacing the inner and outer cylinders with other radius sizes;

[0030] Angular velocity w of inner cylinder 3 i , angular velocity ω of outer cylinder 2 o The axial distance (eccentricity) e between the inner and outer cylinders can be accurately controlled in real time, and the position of the nylon particles in the flow field can be observed in real time through the imaging device 4.

[0031] The steps to manipulate the motion of nylon particles using eccentric cylindrical flow are as follows:

[0032] Step 1: After cleaning the inner tube 3 and the outer tube 2, pour the PDMS solution into the outer tube 2, introduce the nylon particles into the particle manipulation area of ​​the outer tube 2, and observe the nylon particles through the imaging device 4;

[0033] Step 2: Take the center of the inner cylinder 3 as the coordinate origin, establish an xy rectangular coordinate system, and use this coordinate system as the reference coordinate system, take the current coordinates of the nylon particle as the starting point of the trajectory, and select a curve in the control area as the control trajectory of the nylon particle;

[0034] Step 3: Discretize the entire trajectory motion time at set time intervals to determine the direction and magnitude of the trajectory velocity in each time interval;

[0035] Step 4: The velocity direction of the nylon particles is considered to be consistent with the velocity direction of the flow field at this point. According to the velocity direction and magnitude obtained in step 3, the angular velocity ω of the inner cylinder 3 corresponding to each time interval can be obtained by using the finite difference method combined with the analytical solution of the eccentric cylindrical flow. i , angular velocity ω of outer cylinder 2 o The axial distance (eccentricity) between the inner and outer cylinders is e;

[0036] Step 5: According to the data obtained in step 4, adjust the angular velocity w of the inner tube 3 in real time i , the angular velocity w of the outer cylinder 2 o The axial distance (eccentricity) e between the inner and outer cylinders makes the nylon particles move along the set direction, and finally realizes the movement of the nylon particles along the set trajectory.

[0037] The present invention can continuously adjust the speed direction and size of the point where the particles are located by changing the angular velocity and the axis distance (eccentricity) of the inner cylinder 3 and the outer cylinder 2 in real time under the condition of a given radius ratio of the inner cylinder 3 and the outer cylinder 2, thereby accurately controlling the motion trajectory of the nylon particles. The nylon particles in this method have a large motion range and a simple control method.

[0038] from Figure 2 It can be seen that the inner cylinder 3 is placed inside the outer cylinder 2, with a gap between the two; the axes of the two are parallel but not coaxial; the two can rotate relative to each other (including rotating in the same direction or in the opposite direction), and the speeds can be adjusted independently.

[0039] The source of the analytical solution of eccentric cylindrical flow is: Ballal BY, Rivlin R S. Flow of a Viscoelastic Fluid Between Eccentric Rotating Cylinders[J]. Transaction of the Society of Rheology. 1976, 1(20): 65-101.

[0040] The imaging device 4 is an industrial camera.

[0041] As described above, under a given radius ratio of the inner cylinder 3 and the outer cylinder 2, the present invention continuously adjusts the direction and magnitude of the flow field velocity at the point where the particle is located by changing the angular velocity and the axis distance of the inner cylinder 3 and the outer cylinder 2 in real time, so that the controlled particle moves in the set direction, thereby achieving the purpose of controlling the particle motion trajectory.

[0042] Compared with the currently known fluid dynamic particle manipulation methods, the present invention has the characteristics of large particle movement range, simple control method and small flow field force, and can provide a new experimental means for cutting-edge scientific fields such as microbial analysis, disease diagnosis, and drug transportation.

[0043] The implementation methods of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for controlling particle motion using eccentric cylindrical flow, characterized in that The steps include: Step 1: placing the controlled particle (1) in a flow field between an inner cylinder (3) and an outer cylinder (2) whose axes are parallel and coaxial; the flow field serves as a control area for the controlled particle (1); Acquiring real-time motion data of controlled particles (1) in the flow field through an imaging device (4); Step 2: Based on the real-time dynamic data obtained in step 1, a rectangular coordinate system is established with the center of the inner cylinder (3) as the origin of the coordinates, and the current coordinates of the controlled particle (1) are used as the starting point of the trajectory. An arbitrary curve is selected within the control area of ​​the controlled particle (1) as the control trajectory of the particle; Step 3: Select appropriate time intervals according to accuracy requirements to discretize the entire trajectory motion time and determine the velocity direction and magnitude of the trajectory within each time interval; Step 4: The velocity direction of the controlled particle (1) is considered to be consistent with the velocity direction of the flow field at the starting point of the trajectory; according to the velocity direction and magnitude obtained in step 3, the angular velocity of the inner cylinder (3), the angular velocity of the outer cylinder (2) and the axial distance between the inner and outer cylinders corresponding to each time interval are obtained by using the finite difference method combined with the analytical solution of the eccentric cylindrical flow. e data; Step 5: Based on the data obtained in step 4, adjust the angular velocity of the inner cylinder (3), the angular velocity of the outer cylinder (2) and the axial distance between the inner and outer cylinders in real time e , so that the controlled particle (1) moves along a set direction, and finally the controlled particle (1) moves along a set trajectory in the flow field.

2. The method for controlling particle motion using eccentric cylindrical flow according to claim 1, characterized in that: The real-time motion data in step 1 refers to the real-time position of the controlled particle (1) in the flow field.

3. The method for controlling particle motion using eccentric cylindrical flow according to claim 2, characterized in that: The angular velocity of the inner cylinder (3) and the outer cylinder (2) can be adjusted in real time, or the angular velocity ratio of the inner cylinder (3) and the outer cylinder (2) can be adjusted in real time.

4. The method for controlling particle motion using eccentric cylindrical flow according to claim 3, characterized in that: The axial distance between the inner cylinder (3) and the outer cylinder (2) can be adjusted in real time, or the eccentricity ratio between the inner cylinder (3) and the outer cylinder (2) can be adjusted in real time.

5. The method for controlling particle motion using eccentric cylindrical flow according to claim 2, characterized in that: The controlled particles (1) are polymer particles, drug-loaded particles, cells, micro-nano devices, droplets, microbubbles or dynamic organisms.

6. The method for controlling particle motion using eccentric cylindrical flow according to any one of claims 1 to 5, characterized in that: The geometric shapes of the outlines of the inner cylinder (3) and the outer cylinder (2) are circular, elliptical or rectangular.

7. The method for controlling particle motion using eccentric cylindrical flow according to claim 6, characterized in that: The flow field is filled with PDMS solution.

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