Multi-particle optical control and sorting method and device

Abstract

The invention relates to the technical field of optical micro-control, in particular to a multi-particle optical control and sorting method and device. The invention aims to solve the problem of difficulty in optical control of a multi-particle system. The optical control and sorting method comprises the following steps: constructing a tripolymer particle system consisting of three isotropic micro-nano particles in a uniform liquid medium, wherein the tripolymer particle system is completely immersed in the liquid medium and has a symmetry axis vertical to the surface of the liquid medium; the method comprises the steps that a linear polarization Gaussian beam passes through a polarization adjusting module, a shaping and beam expanding module and an incident angle adjusting module according to a preset sequence, and enters a trimer particle system from the position above the surface of a liquid medium according to a preset mode; by adjusting the polarization adjusting module and the incident angle adjusting module, the motion direction and the motion speed of the tripolymer particle system are optically controlled. The device comprises a sample table, a laser emitting module and an optical control assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical micro-manipulation, and more particularly, to a method and device for multi-particle optical manipulation and sorting. BACKGROUND

[0002] Optical manipulation technology has become an important means of micro-nano particle manipulation, and is widely used in particle sorting, classification, ordering and other fields, especially in biomedical, environmental monitoring, materials science and other industries. By precisely controlling the optical field, optical force can achieve non-contact manipulation of micro-nano particles, with the advantages of high efficiency, flexibility and accuracy. However, in the prior art, how to effectively manipulate and sort multiple particles, especially in complex multi-particle systems, still faces many challenges. Traditional optical manipulation methods usually rely on optical gradient force and scattering force to attract or push particles through light intensity gradient, but for the manipulation of multi-particle systems, especially the realization of transverse optical force in symmetric particle pairs (such as multimers), there are still great difficulties.

[0003] Currently, optical manipulation strategies rely on complex structured light beams, special interface designs or multi-beam synthesis. Although these methods can effectively manipulate particles, they often face problems such as complex structure, high cost, and difficult adjustment in operation.

[0004] In the prior art, some research has proposed different optical manipulation schemes. For example, patent CN202411899389.8 relates to a microfluidic chip system combining optical tweezers and light-induced bubble technology, which realizes the manipulation of single cells or single droplets by generating bubbles with laser. The system can accurately position the target single cell and capture and rotate the particles by controlling the optical tweezers technology and the light-induced bubble technology. Although this method has high manipulation precision, the system design is complex, and the operator needs to have high technical level, and in practical application, the stability and reliability of the system may be affected, especially when multiple optical components are used simultaneously, the failure risk is high, and the cost is high.

[0005] In addition, patent CN202280090882.8 proposes a light manipulation system based on multiple reflectors and chambers, which realizes efficient control of light through the combination of light filtering equipment and probes. The system relies on complex optical structures such as multiple reflectors and chambers, which has certain advantages in optical precision, but the structure is complex, the debugging difficulty is large, and the professional skill requirement of the operator is high. At the same time, the stability and cost of the system are also difficult problems to be solved in practical application. SUMMARY

[0006] The present application aims to overcome at least one of the above-mentioned defects of the prior art, and provides a multi-particle optical manipulation and sorting method and device to solve the problem of difficult optical manipulation of a multi-particle system.

[0007] A first object of the present application is to provide a multi-particle optical manipulation and sorting method, in which a trimer particle system composed of three isotropic micro-nano particles is constructed in a uniform liquid medium, the trimer particle system has an isosceles triangular structure and is completely immersed in the liquid medium, the trimer particle system includes a dimer unit composed of two micro-nano particles with the same diameter and a single particle unit composed of one micro-nano particle, the axis of the dimer unit corresponds to the base of the isosceles triangular structure, and the single particle unit is assembled at the midpoint of the axis, and the axis is parallel to the surface of the liquid medium. The method comprises: A linearly polarized Gaussian light beam is passed through a polarization adjustment module, a shaping and expanding module, and an incident angle adjustment module in a predetermined order, and is incident on the trimer particle system from above the surface of the liquid medium in a predetermined manner. The movement direction and speed of the trimer particle system are optically manipulated by adjusting the polarization adjustment module and the incident angle adjustment module. The predetermined manner includes: processing the linearly polarized Gaussian light beam by the shaping and expanding module to make the spot of the linearly polarized Gaussian light beam projected on the surface of the liquid medium have an elliptical shape with a major axis and a minor axis, the major axis is perpendicular to the incident direction of the linearly polarized Gaussian light beam, and the axis of the dimer unit is bound by the short-axis gradient force in the direction of the major axis; and the linearly polarized light beam forms an incident angle of an angle ∈(0°, 90°) with the normal of the surface of the liquid medium after being guided by the incident angle adjustment module, and the polarization direction of the linearly polarized light beam forms a polarization angle of an angle ∈[(-90°, 0°)∪(0°, 90°)] with the major axis after being adjusted by the linearly polarized adjustment module, so as to induce the trimer particle system to generate a transverse optical force parallel to the major axis.

[0008] In the present application, the trimer particle unit of a specific isosceles triangle structure is the necessary basis for subsequent stable and flexible transverse optical force manipulation of the trimer particle unit. Among them, the number of incident angles of linearly polarized Gaussian beam affects the size of the transverse optical force induced when the incident light interacts with the trimer particle system, therefore, by adjusting the incident angle, the movement of the particle in the light field can be ensured to conform to the expected direction, thereby effectively exciting the transverse optical force response of the particle. In addition, the polarization direction of the linearly polarized light beam is diagonal polarization, that is, the polarization direction is neither parallel nor perpendicular to the surface of the liquid medium, in this way, the symmetry of the trimer particle system is broken in the long axis direction of the light spot, providing conditions for the generation of transverse optical force. By jointly regulating the polarization direction and the incident angle, the symmetry of the trimer particle system in the long axis direction of the light spot can be effectively destroyed, and then the transverse displacement of the trimer particle system in the light field is induced, thereby realizing precise optical manipulation of the movement direction and force of the multi-particle system.

[0009] In some embodiments, the preset manner further includes: after the linearly polarized light beam is guided by the incident angle adjusting module, the linearly polarized light beam forms an incident angle of 0° or 90° with the normal of the liquid surface, so as to stop the transverse optical force.

[0010] In some embodiments, the preset manner further includes: after the polarization direction of the linearly polarized light beam is adjusted by the linear polarization adjusting module, the polarization direction forms a polarization angle of 0° or ±90° with the long axis, so as to stop the transverse optical force.

[0011] In some embodiments, the trimer particle system composed of three isotropic micro-nano particles in the uniform liquid medium includes: Different trimer particle systems are constructed by different particle sizes of micro-nano particles in the liquid medium, wherein the three micro-nano particles in any one trimer particle system have the same particle size.

[0012] The response of the micro-nano particle is closely related to the particle size. In the present application, under the action of the transverse optical force, different trimer particle systems produce overall transverse displacement, and the transverse response behavior of the particle is affected by the particle size. Specifically, the trimer particle system constructed by smaller particles responds faster and has larger displacement, while the trimer particle system constructed by larger particles responds slower and has smaller displacement, so that different trimer particle systems can stay at different end positions under the same optical manipulation condition. Based on this, by measuring the displacement difference of the particles under the action of the transverse optical force, the accurate sorting of different particle size particles can be realized.

[0013] In some embodiments, the radius of the micro-nano particle is 50 nm-10 µm.

[0014] In some embodiments, the micro-nano particles are transparent dielectric particles, and there is a refractive index difference between the dielectric particles and the liquid medium.

[0015] In some embodiments, the micro-nano particles are polystyrene particles or silica particles.

[0016] In some embodiments, the ratio of the length of the long axis to the length of the short axis is 3-15.

[0017] In some embodiments, the liquid medium is water or ethanol.

[0018] The second aspect of the present application provides a multi-particle optical manipulation and sorting device, comprising: a sample stage for carrying a uniform liquid medium and an isotropic micro-nano particle sample, wherein the micro-nano particles form a plurality of trimer particle systems in the liquid medium, the trimer particle system has an isosceles triangular structure and is completely immersed in the liquid medium, the trimer particle system includes a dimer unit composed of two micro-nano particles with the same diameter and a single particle unit composed of one micro-nano particle, the axis of the dimer unit corresponds to the base of the isosceles triangular structure, and the single particle unit is placed at the midpoint of the axis, and the axis is parallel to the surface of the liquid medium; a laser exit module for emitting a linearly polarized light beam; an optical manipulation assembly including a polarization adjustment module, a shaping and expanding module, and an incident angle adjustment module, the optical manipulation assembly is configured to make the linearly polarized light beam pass through the polarization adjustment module, the shaping and expanding module, and the incident angle adjustment module in a predetermined order, and the linearly polarized light beam is incident on the trimer particle system from above the surface of the liquid medium in a predetermined manner, wherein the polarization adjustment module and the incident angle adjustment module are further configured to adjust the direction and speed of the trimer particle system; the predetermined manner includes: processing the linearly polarized Gaussian light beam by the shaping and expanding module to make the light spot of the linearly polarized Gaussian light beam projected on the surface of the liquid medium have an elliptical shape with a long axis and a short axis, the long axis is perpendicular to the incident direction of the linearly polarized Gaussian light beam, and the axis of the dimer unit is bound by the short axis gradient force in the direction of the long axis; and the linearly polarized light beam forms an incident angle of a number ∈ (0°, 90°) with the symmetry axis after being guided by the incident angle adjustment module, and the polarization direction of the linearly polarized light beam forms a polarization angle of a number ∈ [(-90°, 0°)∪(0°, 90°)] with the long axis after being adjusted by the linearly polarized adjustment module, so as to induce the trimer particle system to generate a transverse optical force parallel to the long axis.

[0019] In some embodiments, the beam shaping and expanding module comprises a beam shaping lens group and a beam shaper, which are coaxial and arranged in sequence along the propagation direction of the linearly polarized light beam.

[0020] In some embodiments, the laser exit module outputs a linearly polarized light beam with a wavelength of 500-980 nm; and / or, The output power of the laser exit module ranges from 0 to 5 W.

[0021] In some embodiments, the multi-particle optical manipulation and sorting device further comprises an imaging monitoring module for monitoring the position and motion trajectory of the micro-nanoparticle sample and performing imaging.

[0022] Compared with the prior art, the present application has the following advantages: (1) By simplifying the optical design and light source control, precise manipulation and sorting of the multi-particle system can be efficiently realized. This method does not rely on complex optical structures or special materials, significantly reduces the system cost, simplifies the operation process, and improves the feasibility of application.

[0023] (2) The present application can accurately sort particles according to their particle size differences. Different particle sizes exhibit different response behaviors under the action of optical force, thereby realizing efficient particle size sorting. This method has high flexibility and strong adaptability, which can meet various experimental needs.

[0024] (3) By precisely controlling the polarization direction and incident angle of the light source, the present application can stably manipulate the multi-particle system. The method and device of the present application have wide application prospects, especially in the fields of biomedicine, environmental monitoring, and material science. They are suitable for micro-nanoparticle trajectory control, flexible optical transmission, particle ordering and self-assembly, and provide a new solution for micro-nanoparticle sorting. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The flowchart of the multi-particle optical manipulation and sorting method of the present application.

[0026] Figure 2 The structural schematic diagram of the multi-particle optical manipulation and sorting device of the present application.

[0027] Figure 3 The schematic diagram of the trimer particle system composed of isotropic spherical micro-nanoparticles in Example 1 induced by linearly polarized light beam.

[0028] Figure 4The near-field scattering field distribution of the three-particle system constructed by three polystyrene particles with a radius of 50 nm in Test Example 1 of the present application at 50° incident angle condition, using different polarization angles.

[0029] Figure 5 The curve of the transverse optical force with the polarization angle of the three-particle system constructed by three polystyrene particles with a radius of 50 nm in Test Example 1 of the present application at different incident angles.

[0030] Figure 6 The curve of the transverse optical force with the incident angle of the three-particle system constructed by three polystyrene particles with a radius of 50 nm in Test Example 1 of the present application at different polarization angles.

[0031] Figure 7 The near-field scattering field distribution of the three-particle system constructed by three polystyrene particles with a radius of 500 nm in Test Example 2 of the present application at 50° incident angle condition, using different polarization angles.

[0032] Figure 8 The curve of the transverse optical force with the polarization angle of the three-particle system constructed by three polystyrene particles with a radius of 500 nm in Test Example 2 of the present application at different incident angles.

[0033] Figure 9 The curve of the transverse optical force with the incident angle of the three-particle system constructed by three polystyrene particles with a radius of 500 nm in Test Example 2 of the present application at different polarization angles.

[0034] The figure mark: laser exit module 1, polarization adjustment module 2, shaping and beam expanding module 3, incident angle adjustment module 4, sample stage 5, micro-nanoparticle sample 6, half-transmission half-reflection mirror 7, illumination light source 8, focusing lens 9, filter 10, CCD camera 11, computer 12. DETAILED DESCRIPTION

[0035] The drawings of the present application are only for illustrative purposes, and cannot be understood as a limitation of the present application. In order to better illustrate the following embodiments, some components of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable for those skilled in the art that some known structures and their descriptions in the drawings may be omitted.

[0036] Furthermore, in the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be directly connected, or indirectly connected through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements, unless otherwise explicitly limited. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0037] In addition, in the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implying the number of the indicated technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those of ordinary skill in the art. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope required by the present application.

[0038] Embodiment 1 As Figure 1 shown, the present application first provides a multi-particle optical manipulation and sorting method, the steps are as follows: S0. Preprocessing micro-nanoparticles to obtain a trimer particle system, specifically, constructing a trimer particle system assembled by three isotropic micro-nanoparticles in a uniform liquid medium, the trimer particle system is in an isosceles triangle structure and is completely immersed in the liquid medium, the trimer particle system includes a dimer unit composed of two micro-nanoparticles with the same diameter and a single particle unit composed of one micro-nanoparticle, the axis of the dimer unit corresponds to the base of the isosceles triangle structure, and the single particle unit is assembled at the midpoint of the axis, and the axis is parallel to the surface of the liquid medium. It should be pointed out that in specific implementation, the isosceles triangle structure can be arranged parallel to the surface of the liquid medium, or can be arranged perpendicular to the surface of the liquid medium. Among them, the micro-nanoparticles constituting the single particle unit and the micro-nanoparticles constituting the dimer unit can use micro-nanoparticles of different particle sizes, or can use micro-nanoparticles of the same particle size. It can be understood that in the case of using micro-nanoparticles of the same particle size in the single particle unit and the dimer unit, the trimer particle system is in an equilateral triangle structure.

[0039] Among them, the micro-nanoparticles are polystyrene micro-nanoparticles or silica micro-nanoparticles, and the radius of the micro-nanoparticles is 50nm-10µm; the liquid medium requires transparency and refractive index difference with the micro-nanoparticles, so as to effectively transmit optical force; in specific implementation, the liquid medium is water or ethanol.

[0040] S1. A linearly polarized Gaussian light beam is passed through a polarization adjustment module, a shaping and expanding module, and an incident angle adjustment module in a preset order, and is incident on a trimer particle system from above the surface of a liquid medium in a preset manner; wherein the front and back arrangement order of the shaping and expanding module, the incident angle adjustment module, and the polarization adjustment module can be flexibly adjusted. S2. The movement direction and the transverse optical force of the trimer particle system are optically controlled by adjusting the polarization adjustment module and the incident angle adjustment module.

[0041] The preset manner includes: processing the linearly polarized Gaussian light beam through the shaping and expanding module to make the light spot of the linearly polarized Gaussian light beam projected on the surface of the liquid medium be an ellipse with a long axis and a short axis, the long axis being perpendicular to the incident direction of the linearly polarized Gaussian light beam, and the axis of the dimer unit being bound in the long axis direction by the short axis gradient force; and After the linearly polarized light beam is guided through the incident angle adjustment module, an incident angle of a number ∈ (0°, 90°) is formed with the symmetry axis, and after the linearly polarized light beam is adjusted in polarization direction through the linearly polarized adjustment module, a polarization direction forms a polarization angle of a number ∈ [(-90°, 0°)∪(0°, 90°)], so as to induce the trimer particle system to generate a transverse optical force parallel to the long axis. Wherein, the length ratio of the long axis and the short axis of the elliptical light spot is 3-15, so that the gradient force in the long axis direction can be avoided to be too large to interfere with the manipulation of the microparticles based on the transverse optical force, and at the same time, the microparticles can be stably bound in the long axis direction by the short axis gradient force.

[0042] Exemplarily, referring to Figure 2 which shows that the arrangement manner of the three microparticles P1, P2, P3 in the trimer particle system is a symmetrical isosceles triangle structure, and the isosceles triangle structure is perpendicular to the surface of the liquid medium. In order to facilitate understanding, Figure 2An xyz three-dimensional coordinate system is constructed, the x-axis, the y-axis and the z-axis are perpendicular to each other, and the plane formed by the x-axis and the y-axis is parallel to the surface of the liquid medium. Among them, the angle between the incident direction of the linearly polarized light beam and the positive direction of the z-axis is defined as the incident angle, and the angle between the electric field polarization direction of the linearly polarized light beam and the positive direction of the y-axis is defined as the polarization angle. In specific implementation, the elliptical spot of the linearly polarized Gaussian light beam projected on the surface of the liquid medium is stretched and elongated in the y-axis direction, resulting in a decrease in the gradient force of the linearly polarized incident light in the y-axis direction, and the trimer particle system is bound on the y-axis by the short-axis gradient force in the x-axis direction. In specific implementation, in order to facilitate optical manipulation of the trimer particle system, the two micro-nano particles located at the bottom side of the isosceles triangle structure have the same particle size, the axis of the two micro-nano particles is parallel to the y-axis, and when the trimer particle system is bound on the y-axis by the short-axis gradient force in the x-axis direction, the axis is coplanar with the yz plane. In order to ensure the generation of the transverse optical force, the incident angle needs to be adjusted to a non-zero angle (θ≠0°), because the degree of the incident angle affects the size of the transverse optical force induced when the incident light interacts with the trimer particle system, therefore, by adjusting the incident angle, the movement of the micro-nano particles in the optical field can be ensured to conform to the expected direction, thereby effectively exciting the transverse optical force response of the micro-nano particles. In addition, the polarization direction of the linearly polarized light beam is diagonal polarization, that is, the polarization direction is neither parallel nor perpendicular to the surface of the liquid medium, in this way, the symmetry of the trimer particle system in the y-axis direction is broken, providing conditions for the generation of the transverse optical force. The present application can effectively destroy the symmetry of the trimer particle system in the y-axis direction by jointly adjusting the polarization direction and the incident angle, thereby inducing the transverse displacement of the trimer particle system in the optical field, and realizing precise optical manipulation of the movement direction and force of the multi-particle system.

[0043] In some embodiments, the preset mode further includes: after the linearly polarized light beam adjusts the polarization direction through the linear polarization adjustment module, the polarization direction forms a polarization angle with the long axis at an angle of 0° or ±90° to stop the transverse optical force; or, After the linearly polarized light beam adjusts the polarization direction through the linear polarization adjustment module, the polarization direction forms a polarization angle with the long axis at an angle of 0° or ±90° to stop the transverse optical force. It is easy to understand that by stopping the transverse optical force during manipulation, the optical manipulation means of the trimer particle system can be enriched, and the flexibility and applicability can be improved.

[0044] In some embodiments, in step S0, the trimer particle system composed of three isotropic micro-nano particles in the liquid medium includes: Different trimer particle systems are constructed by different particle sizes of micro-nano particles in the liquid medium, wherein the three micro-nano particles contained in any one trimer particle system have the same particle size.

[0045] The research finds that the response of the micro-nano particles is closely related to the particle size, and in the application, under the action of the transverse optical force, different trimer particle systems produce overall transverse displacement, the transverse response behavior of the particles is affected by the particle size, specifically, the trimer particle system constructed by smaller particles responds faster and has larger displacement, while the trimer particle system constructed by larger particles responds slower and has smaller displacement, so that different trimer particle systems can stay at different end positions under the same optical manipulation condition. Based on this, by measuring the displacement difference of the particles under the action of the transverse optical force, the accurate sorting of particles with different particle sizes can be realized.

[0046] Reference Figure 3 The application also provides a multi-particle optical manipulation and sorting device, comprising: A sample table 5 is used to carry a liquid medium and an isotropic sample table 5, wherein a micro-nano particle sample 6 is constructed into several trimer particle systems in the liquid medium, and the trimer particle systems are completely immersed in the liquid medium. A laser exit module 1 is used to emit a linearly polarized light beam. An optical manipulation assembly comprises a beam shaping and expanding module 3, an incident angle adjusting module 4 and a polarization adjusting module 2, and the optical manipulation assembly is used to make the linearly polarized light beam passing through the beam shaping and expanding module 3, the incident angle adjusting module 4 and the polarization adjusting module 2 in a preset order, and the linearly polarized light beam is incident on the trimer particle system from above the surface of the liquid medium in a preset manner, wherein the polarization adjusting module 2 and the incident angle adjusting module 4 are further configured to adjust the motion direction and the motion speed of the trimer particle system.

[0047] In specific implementation, the polarization adjusting module 2, the beam shaping and expanding module 3 and the incident angle adjusting module 4 are arranged in front of the exit end of the laser exit module 1 in sequence. In other embodiments, the sequence of the polarization adjusting module 2, the beam shaping and expanding module 3 and the incident angle adjusting module 4 can be flexibly adjusted according to actual conditions, as long as the linearly polarized light beam passing through the three modules can be incident on the trimer particle system in a preset manner, and those skilled in the art can understand that details are not described herein.

[0048] In some embodiments, the beam shaping and expanding module 3 comprises a beam expanding and collimating lens group and a beam shaper, and the beam expanding and collimating lens group and the beam shaper are coaxial and arranged in sequence along the propagation direction of the linearly polarized light beam.

[0049] In some embodiments, the incident angle adjusting module 4 can be realized by a reflecting mirror.

[0050] In some embodiments, in order to simplify the structure of the device, the beam shaping and expanding module 3 and the incident angle adjusting module 4 can be integrated together.

[0051] In some embodiments, the laser exit module 1 outputs a linearly polarized light beam with a wavelength of 500-980 nm, and the output power of the laser exit module 1 ranges from 0 to 5 W.

[0052] In some embodiments, the multi-particle optical manipulation and sorting device further comprises an imaging monitoring module. In particular implementation, the imaging monitoring module comprises a half-mirror 7, an illumination light source 8, a focusing lens 9, a filter 10, a CCD camera 11, and a computer 12. Specifically, the CCD camera 11 collects the image information of the micro-nano particle sample 6 from the upper surface of the sample stage 5, the half-mirror 7, the focusing lens 9, and the filter 10 are arranged between the sample stage 5 and the illumination light source 8 from bottom to top, the illumination light source 8 irradiates the half-mirror 7, and the computer 12 is electrically connected with the CCD camera 11. In particular operation, the half-mirror 7 is used to separate the illumination light source 8 and the imaging path, the illumination light source 8 is used to illuminate the sample area to ensure clear imaging, the CCD camera 11 captures the image of the sample stage 5 in real time, and the computer 12 processes and analyzes the image to calculate the motion trajectory of the particle under the action of the optical force. It should be noted that the method for the computer 12 to process and analyze the image is the existing technology in the art, which will not be described here.

[0053] Test Example 1 Based on the method described in Example 1, this test example shows the near-field scattering field distribution in the yz plane of a trimer particle system composed of three polystyrene particles (refractive index of 1.5983) with a radius of 50 nm at different polarization angles when the incident angle θ is 50°. It can be seen from the reference Figure 4 that when the polarization angle α is 45°, the scattering field is mainly concentrated in the positive y direction, resulting in a transverse optical force F y > 0; on the contrary, when the polarization angle α is -45°, the scattering field is mainly concentrated in the negative y direction, resulting in a transverse optical force F y > 0; and when the polarization angle α is 0° or ±90°, the scattering field remains mirror symmetric about the xz plane, resulting in a transverse optical force of zero. This result shows that the adjustment of the polarization angle can effectively regulate the response of the particle in the transverse optical force direction, thereby realizing precise particle manipulation.

[0054] Further, in order to verify the characteristics of the transverse optical force changing with the polarization angle, Figure 5 this test example shows the transverse optical force of a trimer particle system composed of three polystyrene particles with a radius of 50 nm changing with the polarization angle under the condition of different sizes of incident angles. Figure 5 It can be seen from the reference yThe relationship between the polarization angle α and the polarization angle α exhibits a clear sinusoidal trend. Specifically, as the polarization angle α changes from -90° to 90°, the transverse optical force F... y It exhibits periodic fluctuations, with the amplitude of these fluctuations increasing with the angle of incidence. At angles of incidence of 0° or 90°, the transverse force remains almost zero. However, when the angle of incidence is oblique [θ∈(0°,90°)], the magnitude of the transverse force exhibits a symmetrical sinusoidal shape as the polarization angle changes, with the maximum value appearing at the polarization angle. α The maximum value is ±45°, while the minimum value occurs at polarization angles of 0° and ±90°. (Continue to refer to...) Figure 5 For example, when the incident angle is 10°, 20°, and 30°, the sinusoidal waveform of the transverse optical force is more prominent, exhibiting a stronger polarization angle dependence. This indicates that the polarization angle has a significant impact on the modulation of the transverse optical force, and this impact intensifies as the incident angle increases. Figure 5 The data shows that transverse optical force is not only affected by the polarization angle, but also strongly modulated by the incident angle. By adjusting the incident angle and polarization angle, the direction of particle motion and response intensity can be precisely controlled, thus providing a flexible means of particle manipulation.

[0055] Figure 6 The transverse optical force F of a trimer particle system constructed from three polystyrene particles with a radius of 50 nm is shown under different polarization angles α. y The law governing the variation of the incident angle θ. Figure 6 The display shows that when the polarization angle α is -45°, -30°, and -15°, the transverse optical force F y All are positive values, and they gradually increase with the increase of the incident angle. θ It reaches its maximum value near -45°C, and then slowly decreases; among which α The transverse optical force amplitude is greatest at -45°, exhibiting the strongest positive response. Conversely, when the polarization angle is... α At angles of 15°, 30°, and 45°, the transverse luminous force is negative, and its absolute value gradually increases with increasing incident angle. Similarly, at... θ The peak value appears around 45°, indicating that the system exhibits symmetrical transverse response directions under positive and negative polarization angles.

[0056] In particular, when the polarization angle α At 0° or ±90°, the transverse optical force remains close to zero and does not change with the incident angle. This result indicates that under these two specific polarization angle conditions, the system maintains its mirror symmetry about the xz plane, thus suppressing the transverse optical force. In contrast, under the asymmetric polarization angle condition ( αUnder the condition of ∈ [(-90°, 0°)∪(0°, 90°)], the light scattering breaks the symmetry of the system in the y direction, making the lateral optical force significantly enhanced with the adjustment of the incident angle. This result further verifies that the generation of the lateral optical force depends on the synergistic effect of the polarization angle and the incident angle. When the polarization angle is fixed, the incident angle plays a decisive role in the size of the lateral optical force; while under different polarization angles, the positive and negative directions and the peak amplitude of the lateral optical force all show regular differences. By reasonably selecting the combination of the polarization angle and the incident angle, the direction and intensity of the lateral motion of the particle system can be accurately controlled, providing a flexible parameter adjustment method for optical sorting and manipulation.

[0057] Test Example 2 In order to further verify the applicability of the method of the present application to different particle size micro-nano particle systems, and to realize the particle size sorting function, three polystyrene particles with a radius of 500 nm are selected to construct a three-particle system in this test example, and other conditions remain the same as in Example 1.

[0058] Due to the increase in particle size, the scattering effect and local electric field distribution between particles are more complex, and the influence on the lateral optical force F y is also more significant. Figure 7 The near-field scattering field distribution in the yz plane under different polarization angles θ when the incident angle α is 52.5° is shown. Figure 7 It can be seen that, similar to Test Example 1, the polarization angle has a decisive influence on the symmetry of the scattering field. When α is 0° and ±90°, the scattering field remains highly symmetric in the y direction, resulting in a lateral optical force close to zero; while when α is ±45°, the scattering field distribution is obviously biased towards the positive y or negative y direction, thereby inducing a significant lateral optical force. Compared with the case of a micro-nano particle radius of 50 nm, the micro-nano particle with a radius of 500 nm exhibits more complex interference fringes in the scattering field, and the local electric field enhancement region is more obvious, reflecting the enhancement of the multiple scattering effect after the increase in particle size.

[0059] Figure 8 The variation of the lateral optical force F y with the polarization angle α under different incident angle sizes is shown. It can be observed that the lateral optical force still presents an approximately sinusoidal periodic variation with the polarization angle, which is consistent with Test Example 1, indicating that the generation mechanism of the lateral optical force with the variation of the polarization angle is universal. When α is ±45°, the lateral optical force reaches the peak value, while when α is 0° and ±90°, the lateral optical force is almost zero. However, unlike the three-particle system with a micro-nano particle radius of 50 nm, the order of magnitude of the lateral optical force is about 10 -4pN / (mW·pm 2 ), the peak transverse optical force in the 500 nm radius trimer system is significantly increased to the order of 10 -1 pN / (mW·pm 2 ). This indicates that the increase of particle radius significantly enhances the interaction between light and particles, thus amplifying the transverse optical force effect.

[0060] Figure 9 Further demonstrates the variation of the transverse optical force F y with the incident angle θ . The results show that the transverse optical force exhibits periodic oscillation characteristics with the change of the incident angle, and the maximum value usually appears in the range of oblique incidence (such as θ 45°-55°), while it almost disappears when θ is 0° or 90°. This trend is consistent with Example 1, indicating that the generation of transverse optical force depends on the condition of breaking the symmetry of the system by incident light. In contrast, the oscillation of the transverse optical force curve in the 500 nm system is more obvious, and the amplitude is higher, showing strong particle size dependence.

[0061] It can be seen that the transverse optical force presents sinusoidal fluctuation with the polarization angle, and periodic enhancement and weakening with the incident angle. However, with the increase of particle size, the order of magnitude of the transverse optical force is significantly improved, and the difference in the lateral displacement of particles in the light field is more prominent. This difference provides a reliable basis for sorting based on particle size, and particles of different sizes can be efficiently distinguished and manipulated under the same light conditions.

[0062] Obviously, the above examples of the present application are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the specific embodiments of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the claims of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for optical manipulation and sorting of multiple particles, characterized in that, A trimer particle system, consisting of three isotropic micro / nano particles, is constructed in a homogeneous liquid medium. The trimer particle system has an isosceles triangular structure and is completely immersed in the liquid medium. The trimer particle system includes a dimer unit composed of two micro / nano particles of the same diameter and a single particle unit composed of one micro / nano particle. The axis of the dimer unit corresponds to the base of the isosceles triangular structure, and the single particle unit is assembled at the midpoint of the axis. The axis is parallel to the surface of the liquid medium. The method includes: A linearly polarized Gaussian beam is passed through a polarization adjustment module, a beam shaping and expanding module, and an incident angle adjustment module in a preset order, and is incident on the trimer particle system from above the surface of the liquid medium in a preset manner. By adjusting the polarization adjustment module and the incident angle adjustment module, the motion direction and speed of the trimer particle system can be optically controlled. The preset method includes: processing the linearly polarized Gaussian beam through the beam shaping and expanding module so that the light spot projected by the linearly polarized Gaussian beam onto the surface of the liquid medium is an ellipse with a major axis and a minor axis, the major axis being perpendicular to the incident direction of the linearly polarized Gaussian beam, and the axis of the dimer unit being bound to the major axis direction by the minor axis gradient force; and, after being guided by the incident angle adjustment module, the linearly polarized beam forms an incident angle of degree ∈ (0°, 90°) with the normal of the surface of the liquid medium, and after the polarization direction of the linearly polarized beam is adjusted by the linear polarization adjustment module, the polarization direction forms a polarization angle of degree ∈ [(-90°, 0°)∪(0°, 90°)] with the major axis, so as to induce the trimer particle system to generate a transverse optical force parallel to the major axis.

2. The method according to claim 1, characterized in that, The preset method further includes: after being guided by the incident angle adjustment module, the linearly polarized beam forms an incident angle of 0° or 90° with the normal of the liquid surface to stop the lateral light force.

3. The method according to claim 1, characterized in that, The preset method further includes: after the polarization direction of the linearly polarized beam is adjusted by the linear polarization adjustment module, the polarization direction forms a polarization angle of 0° or ±90° with the major axis, so as to stop the transverse light force.

4. The method according to any one of claims 1-3, characterized in that, The construction of a trimer particle system consisting of three isotropic micro / nano particles in a homogeneous liquid medium includes: Different trimer particle systems are constructed in the liquid medium using micro- and nano-particles of different sizes, wherein any trimer particle system contains three micro- and nano-particles with the same particle size.

5. The method according to any one of claims 1-3, characterized in that, The radius of the micro-nano particles is 50nm-10µm.

6. The method according to any one of claims 1-3, characterized in that, The micro / nano particles are transparent dielectric particles, and there is a refractive index difference between the dielectric particles and the liquid medium.

7. The method according to any one of claims 1-3, characterized in that, The ratio of the length of the major axis to the length of the minor axis is 3-15.

8. The method according to any one of claims 1-3, characterized in that, The liquid medium is water or ethanol; and / or, the micro / nano particles are polystyrene micro / nano particles or silica micro / nano particles.

9. A multi-particle optical manipulation and sorting device, characterized in that, include: A sample stage is used to hold a homogeneous liquid medium and isotropic micro / nano particle samples. The micro / nano particles are constructed into several trimer particle systems in the liquid medium. The trimer particle systems have an isosceles triangular structure and are completely immersed in the liquid medium. The trimer particle system includes a dimer unit composed of two micro / nano particles of the same diameter and a single particle unit composed of one micro / nano particle. The axis of the dimer unit corresponds to the base of the isosceles triangular structure, and the single particle unit is located at the midpoint of the axis. The axis is parallel to the surface of the liquid medium. Laser emission module for emitting linearly polarized beams; An optical control assembly includes a polarization adjustment module, a beam shaping and expanding module, and an incident angle adjustment module. The optical control assembly is used to direct a linearly polarized light beam that passes through the polarization adjustment module, the beam shaping and expanding module, and the incident angle adjustment module in a preset order to be incident on the trimer particle system from above the surface of the liquid medium in a preset manner. The polarization adjustment module and the incident angle adjustment module are further configured to optically control the movement direction and speed of the trimer particle system. The preset method includes: processing the linearly polarized Gaussian beam through the beam shaping and expanding module so that the light spot projected by the linearly polarized Gaussian beam onto the surface of the liquid medium is an ellipse with a major axis and a minor axis, the major axis being perpendicular to the incident direction of the linearly polarized Gaussian beam, and the axis of the dimer unit being bound to the major axis direction by the minor axis gradient force; and, after being guided by the incident angle adjustment module, the linearly polarized beam forms an incident angle of degree ∈ (0°, 90°) with the axis of symmetry, and after the polarization direction of the linearly polarized beam is adjusted by the linear polarization adjustment module, the polarization direction forms a polarization angle of degree ∈ [(-90°, 0°)∪(0°, 90°)] with the major axis, so as to induce the trimer particle system to generate a transverse optical force parallel to the major axis.

10. The apparatus according to claim 9, characterized in that, The beam shaping and expanding module includes a beam shaping lens group and a beam shaper, wherein the beam shaping lens group and the beam shaper are coaxial and arranged sequentially along the propagation direction of the linearly polarized beam; and / or, The laser emission module outputs a linearly polarized beam with a wavelength of 500-980nm; and / or, The output power range of the laser emission module is 0-5W.

11. The apparatus according to claim 9 or 10, characterized in that, It also includes an imaging monitoring module for monitoring the position and trajectory of the micro / nano particle sample and performing imaging.

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