A thermoelectric optical tweezers device and a particle trapping method based on the thermoelectric optical tweezers device

Abstract

The present invention discloses a thermoelectric optical tweezers device and a particle capturing method based on the thermoelectric optical tweezers device. The device comprises: an optical tweezers beam generating module, a graphene substrate and a surfactant solution layer located on the graphene substrate; the optical tweezers beam generating module is used to generate an optical tweezers beam to enter the surface of the graphene substrate; part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer; the graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer, and the particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient; the particles to be captured are captured under the action of the optical gradient and the electric field. By implementing the present invention, a thermoelectric optical tweezers device with a simple structure is provided. At the same time, the adopted graphene substrate can enable lasers of different wavelengths to generate graphene thermoelectric optical tweezers, thereby achieving full-band capture.

Description

Technical Field

[0001] The present invention relates to the technical field of optical tweezers, and in particular to a thermoelectric optical tweezers device and a particle capturing method based on the thermoelectric optical tweezers device. Background Art

[0002] As a mature optical manipulation technology, optical tweezers technology has been widely used in the manipulation and research of various small-sized materials and even biological cells. At the same time, with the continuous development of optical tweezers technology, a new type of optical tweezers technology has emerged, namely thermoelectric optical tweezers technology. Thermoelectric nano-optical tweezers use the photogenerated thermoelectric field to achieve optical confinement of charged nanomaterials, which is actually an optical tweezers system with light-heat-electric-mechanical multi-field coupling.

[0003] Traditional optical tweezers have high power requirements and poor capture stability. The emergence of thermoelectric optical tweezers technology makes it possible to design low-power optical tweezers. For example, the power of the optical tweezers can be reduced by improving the photothermal conversion efficiency of the substrate material or the thermoelectric conversion efficiency of the microfluidic system. However, as a new type of optical tweezers technology, there are few known thermoelectric optical tweezers and the existing thermoelectric optical tweezers are relatively complex in structure. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a thermoelectric optical tweezers device and a particle capturing method based on the thermoelectric optical tweezers device to solve the technical problems of the existing thermoelectric optical tweezers device.

[0005] The technical solution proposed by the present invention is as follows:

[0006] A first aspect of an embodiment of the present invention provides a thermoelectric optical tweezers device, which includes: an optical tweezers beam generating module, a graphene substrate, and a surfactant solution layer located on the graphene substrate; the optical tweezers beam generating module is used to generate an optical tweezers beam to enter the surface of the graphene substrate; part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer; the graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer, and the particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient; the particles to be captured are captured under the action of the optical gradient and the electric field.

[0007] Furthermore, the thermoelectric optical tweezers device also includes: a light source and an image sensor, wherein the light source is used to illuminate the graphene substrate, and the image sensor is used to observe whether the particles to be captured are captured.

[0008] Furthermore, the thermoelectric optical tweezers device also includes: a beam splitting module, which is used to transmit the optical tweezers light beam to the graphene substrate, and transmit the image formed by the light source illumination on the graphene substrate to the image sensor.

[0009] Furthermore, the thermoelectric optical tweezers device also includes: a control unit and a movable stage, the control unit is connected to the optical tweezers generation module, the image sensor and the movable stage, and the graphene substrate is arranged on the movable stage.

[0010] Furthermore, the thermoelectric optical tweezers device also includes: an objective lens, through which the optical tweezers beam generated by the optical tweezers beam generating module enters the surface of the graphene substrate.

[0011] Furthermore, the optical tweezers beam generating module comprises: a laser and a beam expander lens group, and the laser light generated by the laser is used to generate an optical tweezers beam for matching the entrance pupil of the objective lens through the beam expander lens group.

[0012] Furthermore, the surfactant solution layer includes: water and a surfactant dissolved in the water.

[0013] Furthermore, the surfactant is hexadecyltrimethylammonium chloride.

[0014] Furthermore, the graphene substrate includes a glass sheet and a graphene layer located on the glass sheet.

[0015] A second aspect of an embodiment of the present invention provides a particle capturing method based on a thermoelectric optical tweezers device, the method comprising: placing particles to be captured and a surfactant solution on a graphene substrate to form a surfactant solution layer containing the particles to be captured; irradiating an optical tweezers beam generated by an optical tweezers beam generating module into the surface of the graphene substrate, part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer, the graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer, the particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient; the particles to be captured are captured under the action of the optical gradient and the electric field.

[0016] The technical solution of the present invention has the following advantages:

[0017] The thermoelectric optical tweezers device and the particle capture method based on the thermoelectric optical tweezers device provided by the embodiment of the present invention, wherein the thermoelectric optical tweezers device is composed of only an optical tweezers beam generation module, a graphene substrate, and a surfactant solution layer located on the graphene substrate, and has a simple structure. At the same time, the optical tweezers beam generation module is used to form an optical gradient and a thermal gradient in the surfactant solution layer on the graphene substrate, and the particles in the surfactant solution layer will form an electric field under the thermal gradient according to the Soret effect, thereby, the particles to be captured are captured under the combined action of the optical gradient force and the electric field force, which can make the particle capture process easier.

[0018] The thermoelectric optical tweezers device provided by the embodiment of the present invention sets the surfactant solution layer on the graphene substrate. Since graphene is a full-band saturable absorber, the wavelength of the optical tweezers light beam generated by the optical tweezers generation module is not limited, that is, lasers of different wavelengths can generate graphene thermoelectric optical tweezers. At the same time, the electric field force has universality in capturing particles. Therefore, the use of the graphene substrate makes the application range of the thermoelectric optical tweezers device more extensive. At the same time, the graphene substrate can be prepared by the graphene layer transfer method, and a relatively low thickness graphene layer can be achieved, further expanding the application range of the thermoelectric optical tweezers device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a structural block diagram of a thermoelectric optical tweezers device in an embodiment of the present invention;

[0021] Figure 2 is a structural block diagram of a thermoelectric optical tweezers device in another embodiment of the present invention;

[0022] Figure 3 is a structural block diagram of a thermoelectric optical tweezers device in another embodiment of the present invention;

[0023] Figure 4 Flow chart of a particle capturing method based on a thermoelectric optical tweezers device in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The embodiment of the present invention provides a thermoelectric optical tweezers device, such as Figure 1 As shown, the thermoelectric optical tweezers device includes: an optical tweezers beam generating module 100, a graphene substrate 200, and a surfactant solution layer 300 located on the graphene substrate 200; the optical tweezers beam generating module 100 is used to generate an optical tweezers beam to enter the surface of the graphene substrate 200; part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer 300; the graphene layer in the graphene substrate 200 absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer 300, and the particles to be captured on the graphene substrate 200 and the particles in the surfactant solution layer 300 form an electric field under the action of the thermal gradient; the particles to be captured are captured under the action of the optical gradient and the electric field.

[0029] Optionally, the surfactant solution layer 300 may be composed of water and a surfactant. The surfactant may be cetyltrimethyl ammonium chloride (CTAC), and the particles to be captured may also be located in the surfactant solution layer. Specifically, the particles to be captured and the surfactant solution may be directly dropped onto the graphene substrate 200 to form the surfactant solution layer 300.

[0030] Alternatively, if Figure 2 As shown, the graphene substrate 200 can be composed of a glass sheet 201 and a graphene layer 202 on the glass sheet 201. Specifically, the graphene layer can be pre-set on the copper foil, and then the graphene layer on the copper foil can be transferred to the glass sheet by wet transfer, dry transfer or hot stripping tape transfer method. Among them, dry transfer and wet transfer can include spin coating polymethyl methacrylate (PMMA), copper removal, baking, degumming, cleaning and other processes. The hot stripping tape transfer method can use hot stripping tape as a supporting film, so the transfer process does not involve acetone treatment (wet method) in the degumming process, nor does it involve high temperature treatment (dry method), so the hot stripping tape transfer method can be used to transfer graphene to an organic substrate that is not resistant to acetone and high temperature. The embodiment of the present invention does not limit the transfer process of graphene.

[0031] Optionally, when a graphene layer is formed on a glass sheet by a transfer method, an existing graphene layer prepared on a copper foil can be used for direct transfer. Currently, the thickness of the graphene layer prepared on the copper foil is mostly 0.34 nanometers. Therefore, when preparing the graphene substrate 200, only one graphene layer can be transferred, that is, the thickness of the graphene layer 202 in the formed graphene substrate 200 can be 0.34 nanometers; in addition, multiple graphene layers can also be transferred, that is, the thickness of the graphene layer 202 in the formed graphene substrate 200 can be 0.68 nanometers, 1.02 nanometers, etc.

[0032] Specifically, when the optical tweezers beam enters the surface of the graphene substrate, part of the energy in the optical tweezers beam can pass through the graphene layer to form a light field distribution in the surfactant solution layer. The optical gradient force can be used to move the particles to be captured to the focus and be captured.

[0033] At the same time, when the optical tweezers beam passes through the graphene substrate, the graphene layer in the graphene substrate will also absorb part of the energy in the optical tweezers beam to generate heat, forming a thermal gradient from the focus to the outside in the surfactant solution layer. At this time, a part of the CTAC molecules in the surfactant solution layer will be adsorbed on the surface of the particles to be captured to form a positively charged molecular double layer. At the same time, when the concentration of CTAC molecules is higher than the critical micelle concentration (0.13mmol / L-0.16mmol / L), the CTAC molecules self-assemble into micelles. At this time, particles, micelles and chloride ions with different charges move to the cold end and the hot end respectively according to the Soret effect, forming a concentration gradient, resulting in charge non-conservation and thus constructing an electric field. The direction of the electric field points to the direction of the laser focus. Since the particles to be captured adsorbed by the CTAC molecules are positively charged, the particles to be captured move to the focus under the action of the electric field and are captured.

[0034] The thermoelectric optical tweezers device provided by the embodiment of the present invention is only composed of an optical tweezers beam generation module, a graphene substrate, and a surfactant solution layer located on the graphene substrate, and has a simple structure. At the same time, the optical tweezers beam generation module is used to form an optical gradient and a thermal gradient in the surfactant solution layer on the graphene substrate, and the particles in the surfactant solution layer will form an electric field under the thermal gradient according to the Soret effect, thereby, the particles to be captured are captured under the combined action of the optical gradient force and the electric field force, which can make the particle capture process easier.

[0035] The thermoelectric optical tweezers device provided by the embodiment of the present invention sets the surfactant solution layer on the graphene substrate. Since graphene is a full-band saturable absorber, the wavelength of the optical tweezers light beam generated by the optical tweezers generation module is not limited, that is, lasers of different wavelengths can generate graphene thermoelectric optical tweezers. At the same time, the electric field force has universality in capturing particles. Therefore, the use of the graphene substrate makes the application range of the thermoelectric optical tweezers device more extensive. At the same time, the graphene substrate can be prepared by the graphene layer transfer method, and a relatively low thickness graphene layer can be achieved, further expanding the application range of the thermoelectric optical tweezers device.

[0036] In one embodiment, if Figure 3As shown, the thermoelectric optical tweezers device also includes: a light source 8 and an image sensor 10, the light source 8 is used to illuminate the graphene substrate 200, and the image sensor 10 is used to observe whether the particles to be captured are captured. Specifically, the light source 8 can be a white light source, and the light source 8 can be arranged above the graphene substrate 200, so as to facilitate the illumination of the graphene substrate 200, and at the same time, the particle capture situation on the graphene substrate 200 can be transmitted to the image sensor 10. Optionally, the image sensor 10 can be a charge coupled device (CCD) or other image acquisition devices. Optionally, a lens 9 can be arranged in front of the image sensor 10 to image the capture situation on the graphene substrate 200 on the image sensor 10.

[0037] In one embodiment, if Figure 3 As shown, the thermoelectric optical tweezers device further includes: a beam splitting module 5, which is used to transmit the optical tweezers beam to the graphene substrate 200, and transmit the image formed by the light source 8 on the graphene substrate 200 to the image sensor 10. Optionally, the beam splitting module 5 can select a beam splitter. Specifically, the beam splitting module 5 can be arranged between the optical tweezers beam generating module 100 and the graphene substrate 200.

[0038] In one embodiment, if Figure 3 As shown, the thermoelectric optical tweezers device also includes: a control unit 11 and a movable stage (not shown in the figure), the control unit 11 is connected to the optical tweezers beam generation module 100, the image sensor 10 and the movable stage, and the graphene substrate 200 is arranged on the movable stage. Specifically, the control unit 11 is connected to the image sensor 10, and the image captured by the image sensor 10 can be obtained and displayed, and the power of the laser in the optical tweezers generation module can be adjusted according to the capture status and particle size of the particles to be captured displayed in the image. In addition, the control unit 11 connected to the movable stage can move the stage according to the focus of the optical tweezers beam so that the focus is on the graphene layer 202.

[0039] In one embodiment, if Figure 3 As shown, the thermoelectric optical tweezers device also includes: an objective lens 6, and the optical tweezers beam generated by the optical tweezers beam generating module 100 enters the surface of the graphene substrate 200 through the objective lens 6. Optionally, the optical tweezers beam generating module 100 includes: a laser 1 and a beam expander group, and the laser generated by the laser 1 generates an optical tweezers beam for matching the entrance pupil of the objective lens 6 through the beam expander group. Specifically, the optical tweezers beam can improve the quality of the formed beam by passing through the objective lens, and the beam expander group can include a lens 2 and a lens 3. In addition, a polarizer can be set in the direction of the output light of the laser 1, and the laser 1 can be replaced by a selected silicon chip emitter integrated array to generate an optical vortex beam, which can make the particles to be captured rotate after being captured.

[0040] In one embodiment, if Figure 3 As shown, the thermoelectric optical tweezers device further includes: a reflector 4, which is used to reflect the optical tweezers beam to the beam splitting module 5. Specifically, the setting of the reflector 4 can make the optical path turn. When the components in the thermoelectric optical tweezers device need to be placed together, the reflector 4 can be set in the device to change the optical path of the beam transmission.

[0041] The embodiment of the present invention also provides a particle capture method based on a thermoelectric optical tweezers device, such as Figure 4 As shown, the method comprises the following steps:

[0042] Step S101: placing the particles to be captured and the surfactant solution on a graphene substrate to form a surfactant solution layer containing the particles to be captured; optionally, the surfactant solution layer can be composed of water and a surfactant. The surfactant can be cetyltrimethyl ammonium chloride (CTAC), and the particles to be captured can also be located in the surfactant solution layer. Optionally, the graphene substrate can be composed of a glass sheet and a graphene layer on the glass sheet. The thickness of the graphene layer can be 0.34 nanometers, 0.68 nanometers, 1.02 nanometers, etc. depending on the number of layers transferred.

[0043] Step S102: The optical tweezers beam generated by the optical tweezers beam generating module is emitted into the surface of the graphene substrate. Part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer. The graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer. The particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient.

[0044] Specifically, when the optical tweezers beam enters the surface of the graphene substrate, part of the energy in the optical tweezers beam can pass through the graphene to form a light field distribution in the surfactant solution layer, and the optical gradient force can be used to make the particles to be captured move to the focus; at the same time, when the optical tweezers beam passes through the graphene substrate, the graphene layer in the graphene substrate will also absorb part of the energy in the optical tweezers beam to generate heat, forming a thermal gradient from the focus to the outside in the surfactant solution layer. At this time, part of the CTAC molecules in the surfactant solution layer will be adsorbed on the surface of the particles to be captured to form a positively charged molecular double layer. At the same time, when the concentration of CTAC molecules is higher than the critical micelle concentration (0.13mmol / L-0.16mmol / L), the CTAC molecules self-assemble into micelles. At this time, particles, micelles and chloride ions with different charges move to the cold end and the hot end respectively according to the Soret effect, forming a concentration gradient, resulting in charge non-conservation and thus constructing an electric field. The direction of the electric field points to the direction of the laser focus. Since the particles to be captured adsorbed by the CTAC molecules are positively charged, the particles to be captured move to the focus under the action of the electric field.

[0045] Step S103: The particles to be captured are captured under the action of the optical gradient and the electric field. Specifically, the particles to be captured can be captured under the combined action of the optical gradient force and the electric field force on the graphene substrate.

[0046] The particle capturing method based on the thermoelectric optical tweezers device provided in the embodiment of the present invention uses an optical tweezers beam generating module to form an optical gradient and a thermal gradient in the surfactant solution layer on the graphene substrate. The particles in the surfactant solution layer will form an electric field under the thermal gradient according to the Soret effect. Thus, the particles to be captured are captured under the combined action of the optical gradient force and the electric field force, which can make the particle capturing process easier.

[0047] The particle capture method based on the thermoelectric optical tweezers device provided by the embodiment of the present invention sets the surfactant solution layer on the graphene substrate. Since graphene is a full-band saturable absorber, the wavelength of the optical tweezers light beam generated by the optical tweezers generation module is not limited, that is, lasers of different wavelengths can generate graphene thermoelectric optical tweezers. At the same time, the electric field force has universality in capturing particles. Therefore, the use of the graphene substrate makes the application range of the particle capture method based on the thermoelectric optical tweezers device wider. At the same time, the graphene substrate can be prepared by the graphene layer transfer method, and a relatively low thickness graphene layer can be achieved, further expanding the application range of the method.

[0048] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the present invention and the scope of protection defined by the appended claims, and such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should readily understand that the order of the process steps may be changed while maintaining the scope of protection of the present invention.

[0049] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufactures, material compositions, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be easily understood by those skilled in the art that the processes, mechanisms, manufactures, material compositions, means, methods or steps that currently exist or will be developed in the future, which perform substantially the same functions as the corresponding embodiments described in the present invention or obtain substantially the same results, can be applied according to the present invention. Therefore, the claims attached to the present invention are intended to include these processes, mechanisms, manufactures, material compositions, means, methods or steps within their scope of protection.

Claims

1. A thermoelectric optical tweezers device, characterized in that: include: An optical tweezers beam generating module, a graphene substrate and a surfactant solution layer located on the graphene substrate, wherein the surfactant solution layer comprises: water and a surfactant dissolved in the water, wherein the surfactant is hexadecyltrimethylammonium chloride, and the graphene substrate comprises a glass sheet and a graphene layer located on the glass sheet; The optical tweezers beam generating module is used to generate an optical tweezers beam to enter the surface of the graphene substrate; Part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer; The graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer, and the particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient; The particles to be captured are captured under the action of light gradient and electric field; The particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient, including: When a thermal gradient is formed in the surfactant solution layer, a part of the CTAC molecules in the surfactant solution layer will be adsorbed on the surface of the particles to be captured to form a positively charged molecular bilayer. When the concentration of CTAC molecules is higher than the critical micelle concentration, the CTAC molecules self-assemble into micelles. At this time, particles, micelles and chloride ions with different charges move to the cold end and the hot end respectively according to the Soret effect, forming a concentration gradient, resulting in charge non-conservation and thus constructing an electric field.

2. The thermoelectric optical tweezers device according to claim 1, characterized in that: Also includes: A light source and an image sensor, wherein the light source is used to illuminate the graphene substrate, and the image sensor is used to observe whether the particles to be captured are captured.

3. The thermoelectric optical tweezers device according to claim 2, characterized in that: Also includes: A beam splitting module is used to transmit the optical tweezers beam to the graphene substrate, and transmit the image formed by the light source illumination on the graphene substrate to the image sensor.

4. The thermoelectric optical tweezers device according to claim 2, characterized in that: Also includes: A control unit and a movable stage, wherein the control unit is connected to the optical tweezers beam generating module, the image sensor and the movable stage, and the graphene substrate is arranged on the movable stage.

5. The thermoelectric optical tweezers device according to claim 1, characterized in that: Also includes: An objective lens, through which the optical tweezers beam generated by the optical tweezers beam generating module enters the surface of the graphene substrate.

6. The thermoelectric optical tweezers device according to claim 5, characterized in that: The optical tweezers beam generation module comprises: a laser and a beam expander lens group. The laser light generated by the laser is used to generate an optical tweezers beam for matching the entrance pupil of the objective lens through the beam expander lens group.

7. A particle capture method based on a thermoelectric optical tweezers device, characterized in that: include: Placing the particles to be captured and the surfactant solution on a graphene substrate to form a surfactant solution layer containing the particles to be captured, wherein the surfactant solution layer comprises: water and a surfactant dissolved in the water, wherein the surfactant is hexadecyltrimethylammonium chloride, and the graphene substrate comprises a glass sheet and a graphene layer on the glass sheet; The optical tweezers beam generated by the optical tweezers beam generating module is injected into the surface of the graphene substrate, part of the energy in the optical tweezers beam forms an optical gradient in the surfactant solution layer, the graphene layer in the graphene substrate absorbs part of the energy in the optical tweezers beam to form a thermal gradient in the surfactant solution layer, and the particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient; The particles to be captured are captured under the action of light gradient and electric field; The particles to be captured on the graphene substrate and the particles in the surfactant solution layer form an electric field under the action of the thermal gradient, including: When a thermal gradient is formed in the surfactant solution layer, a part of the CTAC molecules in the surfactant solution layer will be adsorbed on the surface of the particles to be captured to form a positively charged molecular bilayer. When the concentration of CTAC molecules is higher than the critical micelle concentration, the CTAC molecules self-assemble into micelles. At this time, particles, micelles and chloride ions with different charges move to the cold end and the hot end respectively according to the Soret effect, forming a concentration gradient, resulting in charge non-conservation and thus constructing an electric field.

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