Device for sorting particles in liquid based on thermoelectric optical tweezers

Abstract

The utility model discloses a device for sorting particles in liquid based on thermoelectric optical tweezers. The device comprises a laser, a filter, a beam expanding module, a dichroscope, an objective lens, an illumination and imaging module and a capturing and sorting module, the emergent power of continuous laser emitted by the laser device is changed through the filter, the continuous laser is expanded by the beam expanding module and then is reflected and coupled by the dichroic mirror to enter the objective lens, the focused laser acts on the glass sample pool covered with the graphene film, and movement of an electric displacement table in the capturing and sorting module is controlled to achieve particle sorting. The optical tweezers with the laser-induced thermoelectric effect are used for sorting particles, and the problem that potential thermal damage exists in samples due to the fact that the laser power in traditional optical sorting is too high is solved. The sorting of various types of particles is realized by changing the speed of the displacement table, which is of great significance to the application of the optical tweezers technology in the fields of cell sorting, transportation and the like.

Description

Technical Field

[0001] This utility model belongs to the field of optical tweezers technology, and relates to optical tweezers capture and sorting devices, specifically to a device for sorting particles in a liquid based on thermoelectric optical tweezers. Background Technology

[0002] Optical tweezers are a method of manipulating objects using the radiation pressure of light. Unlike traditional mechanical tweezers, they are non-contact, cause no mechanical damage, and allow for precise manipulation. They are widely used in the manipulation of microparticles, especially biomolecules and living cells. However, due to limitations of traditional optical tweezers, firstly, the difference in optical force between Rayleigh and Mie particles caused by shape is very small in traditional optical tweezers systems, resulting in less than ideal performance for shape-based bacterial sorting. Secondly, improving the trapping force of traditional optical tweezers relies on the gradient force provided by a high-power, tightly focused laser, which inevitably causes thermal damage to biological particles and exacerbates Brownian motion, reducing the stability of the trapping process. Summary of the Invention

[0003] The purpose of this invention is to provide a device and method for sorting particles in a liquid based on thermoelectric optical tweezers, so as to solve the problems of high power and low sorting adaptability when using traditional optical tweezers to sort particles in the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0005] A device for sorting particles in a liquid based on thermoelectric optical tweezers includes a laser, a filter, a beam expander, a dichroic mirror, an objective lens, an illumination and imaging module, and a capture and sorting module. The continuous laser emitted by the laser has its output power altered by the filter, and after being expanded by the beam expander, it is reflected and coupled into the objective lens by the dichroic mirror. The focused laser acts on the sample cell in the capture and sorting module, and particle sorting is achieved by controlling the movement speed of the electric displacement stage in the capture and sorting module. The illumination and imaging module, the dichroic mirror, and the objective lens are all on the same optical axis.

[0006] Furthermore, the laser is a 532nm semiconductor continuous laser.

[0007] Furthermore, the filter is an adjustable neutral density filter; the power of the laser emitted by the laser is adjusted by the neutral density filter.

[0008] Furthermore, the beam expander module includes a first lens and a second lens. The distance between the first lens and the second lens is the sum of the focal lengths of the two lenses; the laser light passing through the filter is expanded by the first and second lenses and then reflected by the dichroic mirror into the objective lens.

[0009] Furthermore, the capture and sorting module includes a sample cell and an electric displacement module; the laser focused by the objective lens (5) acts on the sample cell, which is located at the working distance of the objective lens. The sample cell and the electric displacement module are fixed together by a connecting rod.

[0010] Furthermore, the sample cell includes a top glass plate with a central opening and a bottom glass plate of the same size with a central graphene film.

[0011] Furthermore, the electric displacement module includes an electric linear displacement stage and an open-loop controller.

[0012] Furthermore, the illumination and imaging module includes a light-emitting diode and an imaging device; the illumination light passes through the sample cell and is transmitted through the objective lens and dichroic mirror into the imaging device.

[0013] Furthermore, the imaging device is a CCD camera, a CMOS camera, or an ICCD camera.

[0014] This utility model has the following advantages compared with the prior art:

[0015] (1) This invention uses thermoelectric optical tweezers to capture particles and uses laser-induced thermoelectric effect in solution to generate thermoelectric power to particles, thus solving the high power problem of traditional optical tweezers capture.

[0016] (2) Based on the difference in capture stiffness between sorted particles, this utility model can achieve sorting of various types of particles by controlling the speed of the electric linear displacement stage, which solves the problem of low adaptability of optical sorting methods and is of great significance for the practical application of optical tweezers.

[0017] (3) The sorting device of this utility model is easy to implement, easy to operate, low in cost, and easy to promote.

[0018] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0020] Figure 2 This is a scanning electron microscope (SEM) image of the particles sorted according to this invention.

[0021] Figure 3 This is an experimental diagram showing the change in particle capture stiffness as a function of laser power in this invention.

[0022] Figure 4 Experiments for sorting different particles according to this utility model;

[0023] The meanings of the labels in the diagram are as follows: 1-Laser, 2-Filter, 3-Beam expander module, 4-Dichroic mirror, 5-Objective lens, 6-Illumination and imaging module, 7-Acquisition and sorting module;

[0024] 301 - First lens, 302 - Second lens;

[0025] 601 - Light-emitting diode, 602 - Imaging module.

[0026] 701 - Sample cell, 702 - Electric displacement module

[0027] 7011 - Top glass plate, 7012 - Bottom glass plate.

[0028] 7021-Electric linear displacement stage, 7022-Open-loop controller.

[0029] The specific content of this utility model will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0030] It should be noted that the mechanism of particle sorting in liquids using thermoelectric tweezers in this invention is based on the difference in forces experienced by different particles in the thermoelectric tweezers system. The laser emitted from the laser is focused by the objective lens onto the graphene film at the bottom of the sample cell, creating a temperature gradient in the sample solution. The surfactant hexadecyltrimethylammonium chloride in the sample solution adheres to the particle surface, regulating the surface potential of the particles. Furthermore, the surfactant molecules generate a local electric field E under the influence of the thermal gradient. T It can be represented as:

[0031]

[0032] Where i represents the ion type, namely hexadecyltrimethylammonium chloride micelle ion or Cl... - T is the ambient temperature, and e is the elementary charge. Z i n i S Ti Let E represent the charge number, concentration, and Soret coefficient of ion i, respectively. T Pointing the laser beam towards the center will subject the particles encapsulated by hexadecyltrimethylammonium chloride molecules to a thermoelectric force f directed toward the laser center. e Thermal power f e It can be obtained by numerical integration over the electric field and the effective charge q, and the expression is:

[0033]

[0034] The trapping stiffness of a particle describes its ability to be constrained by the trapping potential well within a trapping system. By collecting data on the position distribution of the particle after stable trapping, the variance σ of the position fluctuation after trapping can be obtained by fitting a Gaussian distribution. The trapping stiffness k can be calculated as follows:

[0035] k = k B T / σ 2 (3)

[0036] It should be noted that by calibrating the trapping stiffness between particles, we can achieve particle sorting based on the differences in trapping stiffness. When moving within the sample cell, it experiences viscous resistance f from the solution. d =6πηRu, increasing the moving speed can increase the viscous resistance of the particles as they move with the potential well. Therefore, when the moving speed of the sample cell reaches the threshold, the particle with lower trapping stiffness will no longer escape the potential well as it moves, meaning that the particle with higher trapping stiffness has been sorted.

[0037] It should be noted that, unless otherwise specified, all components in this utility model are components known in the art.

[0038] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0039] Example:

[0040] This embodiment provides a device for sorting particles in a liquid based on thermoelectric optical tweezers, such as... Figure 1 As shown, it includes a laser 1, a filter 2, a beam expander 3, a dichroic mirror 4, an objective lens 5, an illumination and imaging module 6, and a capture and sorting module 7.

[0041] Laser 1 is a 532nm semiconductor continuous laser.

[0042] Filter 2 is an adjustable neutral density filter. The power of the laser emitted from the laser can be adjusted through the neutral density filter.

[0043] The beam expander module 3 includes a first lens 301 and a second lens 302. The first lens 301 has a focal length of 100mm, and the second lens 302 has a focal length of 200mm. It expands the laser beam to the same size as the entrance aperture of the objective lens.

[0044] Dichroic mirror 4 is a dichroic mirror that reflects 532nm laser light and transmits 633nm laser light. The expanded 532nm laser light is reflected and coupled into the objective lens, while the illumination light generated by the transmitted light-emitting diode 601 enters the imaging device 602.

[0045] Objective 5 is a semi-apochromatic oil immersion objective. It has a magnification of 100x and a numerical aperture of 1.3. It is mainly used to focus a 532nm laser onto the sample cell and as the observation objective for imaging device 602.

[0046] The illumination and imaging module 6 includes a light-emitting diode 601 and an imaging device 602. The light-emitting diode 601 emits white light with a wavelength of 440nm-670nm. The imaging device 602, the dichroic mirror 4, and the objective lens 5 are located in a coaxial system.

[0047] The capture and sorting module 7 includes a sample cell 701 and an electric displacement module 702. The sample cell 701 is mainly used to place the samples to be sorted. Figure (2) shows the scanning electron microscope image of the sorted particles. Figure (3) shows the change of capture stiffness with laser power for different particles at a concentration of 3 mM cetyltrimethylammonium chloride.

[0048] The electric sorting module 702 includes an electric linear displacement stage 7021 and an open-loop controller 7022. The electric displacement stage is fixed to the sample cell 701 by a connecting rod. The speed of the electric linear displacement stage 7021, which is also the moving speed of the sample cell 701, is set by the open-loop controller 7022. With a laser power of 2.5mW and a set speed of 0.8μm / s, the images of the two particles in the illumination and imaging module 6 are as follows... Figure 4 As shown in the figure, it can be seen that 500nm PS particles were successfully sorted as the sample cell moved.

[0049] The working process of this utility model is as follows:

[0050] A continuous 532nm laser beam is obtained from laser 1, and the output power is adjusted by rotating the adjustable neutral density filter 2. The first lens 301 and the second lens 302 are used to expand the laser beam, and the distance between the two lenses is 300mm.

[0051] The expanded laser beam is reflected by the dichroic mirror 4 and enters the entrance aperture of the objective lens 5. After being focused, it acts on the graphene thin layer on the bottom glass slide 7012 of the sample cell 601. The particles to be sorted are mixed with a solution of the surfactant cetyltrimethylammonium chloride and then placed in the sample cell 601.

[0052] The power of the rotatable neutral density filter 2 is adjusted to 2.5mW after the objective lens is applied. The light-emitting diode 601 provides illumination light, which is then collected by the imaging device 602 after passing through the sample cell 601, the objective lens 5, and the dichroic mirror 4.

[0053] Images are acquired to monitor the particle capture status in real time. After successfully capturing two types of particles, the speed of the electric linear displacement stage 7021 is controlled by the open-loop controller 7022. Finally, the two particles will be successfully separated after the speed increases to a threshold.

Claims

1. A device for sorting particles in a liquid based on thermoelectric optical tweezers, characterized in that, The system includes a laser (1), a filter (2), a beam expander (3), a dichroic mirror (4), an objective lens (5), an illumination and imaging module (6), and a capture and sorting module (7). The continuous laser emitted by the laser (1) has its output power changed by the filter (2), and after being expanded by the beam expander (3), it is reflected and coupled into the objective lens (5) by the dichroic mirror (4). The focused laser acts on the sample cell in the capture and sorting module (7), and the movement of the displacement stage in the capture and sorting module (7) is controlled to achieve the sorting of particles. The illumination and imaging module (6), the dichroic mirror (4), and the objective lens (5) are on the same optical axis.

2. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 1, characterized in that, The laser (1) is a 532nm semiconductor continuous laser.

3. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 1, characterized in that, The filter (2) is an adjustable neutral density filter; the power of the laser emitted by the laser (1) is adjusted by the neutral density filter.

4. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 1, characterized in that, The beam expander module (3) includes a first lens (301) and a second lens (302); the distance between the first lens (301) and the second lens (302) is the sum of the focal lengths of the two lenses; the laser beam passing through the filter (2) is expanded by the first lens (301) and the second lens (302) and then reflected by the dichroic mirror (4) into the objective lens (5).

5. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 1, characterized in that, The capture and sorting module (7) includes a sample cell (701) and an electric displacement module (702); the laser focused by the objective lens (5) acts on the sample cell (701), which is located at the working distance of the objective lens (5); the sample cell (701) and the electric displacement module (702) are fixed by a connecting rod.

6. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 5, characterized in that, The sample cell (701) includes a top glass plate (7011) with a central opening and a bottom glass plate (7012) of the same size with a central graphene film.

7. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 5, characterized in that, The electric displacement module (702) includes an electric linear displacement stage (7021) and an open-loop controller (7022).

8. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 1, characterized in that, The illumination and imaging module (6) includes a light-emitting diode (601) and an imaging device (602); the illumination light passes through the sample cell (701) and is transmitted through the objective lens (5) and the dichroic mirror (4) into the imaging device (602).

9. The apparatus for separating particles in a liquid using thermoelectric optical tweezers as described in claim 8, characterized in that, The imaging device (602) is a CCD camera, a CMOS camera, or an ICCD camera.

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