CN105182516B - Method for tunable capture and screening of particles above liquid crystal material substrate by linearly polarized planar light waves - Google Patents
Method for tunable capture and screening of particles above liquid crystal material substrate by linearly polarized planar light waves Download PDFInfo
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- CN105182516B CN105182516B CN201510430972.9A CN201510430972A CN105182516B CN 105182516 B CN105182516 B CN 105182516B CN 201510430972 A CN201510430972 A CN 201510430972A CN 105182516 B CN105182516 B CN 105182516B
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Abstract
A method for capturing and screening particles above a liquid crystal material substrate in a tunable manner by linearly polarized planar light waves is characterized in that the particles are placed above a liquid crystal material substrate flat plate, so that the symmetrical distribution of the glass print pavilion vectors around the particles is damaged, the total glass print pavilion vectors on the particles are not zero, and a non-gradient optical force is generated; then, the direction and the size of the total boston vector on the particle are changed by changing the arrangement direction of the liquid crystal molecules (namely the direction of the liquid crystal molecular axis), and further the direction and the size of the non-gradient optical force acted on the particle by the total boston vector are changed, so that the motion trail of the particle in an incident light field is regulated and controlled, and the technical scheme of tunable capture and screening of the nano-sized molecules attached to the surface of the particle is carried out. Wherein the direction of the liquid crystal molecular axis is changed by means of illumination, energization, heating, pressurization, and the like.
Description
Technical Field
The invention relates to a method for capturing and screening particles above a liquid crystal material substrate in a tunable mode by linearly polarized planar light waves, which can be applied to the fields of biology, medicine, nano control and the like.
Background
Optical capture and screening of tiny objects has been a research hotspot in the field of optics. Optical gradient forces play an important role in various optical trapping techniques, such as optical tweezers and optical bundling, etc. achieved by optical gradient forces. However, optical gradient forces have the disadvantages of complex generation equipment, non-tunability, and difficulty in capturing and screening nanometer-sized molecules. In 2008, ward, t.j. et al suggested that chiral molecules with nanometer size could be captured and separated by optical gradient force generated by circularly polarized light. However, the circularly polarized incident light still needs to be generated by using complicated equipment, which is not favorable for the practical application of the system; and the nano-sized molecules that it captures and separates must have a chiral structure, thus limiting the range of their targets of action. Therefore, the invention proposes that nano-sized molecules are covered on the surface of the particles positioned above the liquid crystal material substrate flat plate, so that the nano-sized molecules generate non-gradient optical force around the particles under the irradiation of the linear polarization plane light waves; then, the characteristic that the liquid crystal molecular axis direction of the liquid crystal material changes along with the change of an external optical field, an electric field, a temperature field and a pressure field is utilized to tune the size and the direction of the non-gradient optical force applied to the particles above the liquid crystal material substrate flat plate, so that the capture and the screening of the nano-sized molecules attached to the surfaces of the particles are realized, wherein the nano-sized molecules can be in a non-chiral structure.
Disclosure of Invention
The invention aims to overcome the defects that the traditional method for capturing and screening nano-sized molecules by utilizing gradient optical force is complex in incident light source (namely, the incident light is required to be circularly polarized or elliptically polarized), limited in screening object (namely, the nano-sized molecules are required to have chiral structures), untuneable in gradient optical force generated by circularly polarized light or elliptically polarized light, difficult to capture the nano-sized achiral molecules and the like, and provides a method for capturing and screening the achiral nano-sized molecules above a liquid crystal material substrate flat plate by utilizing the non-gradient optical force generated by linearly polarized planar light waves, which has the advantages of simple system, convenience in operation, super sensitivity, super rapidness, active tuning and the like.
The technical scheme adopted by the invention for solving the problems is as follows:
a method for capturing and screening particles above a liquid crystal material substrate in a tunable manner by linearly polarized planar light waves is characterized in that the particles are placed above a liquid crystal material substrate flat plate, and the liquid crystal material substrate flat plate destroys the symmetrical distribution of the boscalid vectors around the particles, so that the total boscalid vector on the particles is not zero, and a non-gradient optical force is generated; the method comprises the steps of regulating and controlling the motion track of particles in an incident light field by changing the direction of the molecular axis of a liquid crystal material substrate flat plate and the distribution of total glass seal pavilion vectors on the particles and further changing the direction and the size of non-gradient optical force acted on the particles by the total glass seal pavilion vectors, so as to perform tunable capture and screening on nano-sized molecules attached to the surfaces of the particles, wherein the particles are arranged above the liquid crystal material substrate flat plate, the particle material can be a medium or metal, the length, the width and the height of the liquid crystal material substrate are 10 nanometers to 10 meters, and the distance between the particles and the surfaces of the liquid crystal material substrate flat plate is l (l > 0); the shape of the particle can be a curved surface geometry such as a sphere, a cylinder, a cone and the like or a polyhedron such as a prism, a cube, a cuboid and the like, and the volume is 1 cubic nanometer to 1000 cubic micrometers.
The incident light is linearly polarized plane wave; the incident direction of the incident light is parallel to the substrate plate of the liquid crystal material, the frequency range is 0.3-20 microns, and the power range is 0.1 mW/mum 2 ～10mW/μm 2 。
The light source of the incident light adopts a wavelength tunable laser, a semiconductor continuous or quasi-continuous laser or a light emitting diode.
The surface is attached with particles of nanometer-sized molecules, the particle material can be metal or medium, wherein the metal can be Al, ag, au, cu, ni, pt, etc., and the medium can be semiconductor material such as Si, siO 2 、GaAs、InP、Al 2 O 3 Etc. or a polymer.
The liquid crystal material substrate flat plate is characterized in that the liquid crystal material is nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, disc liquid crystal, thermotropic liquid crystal, reproducible liquid crystal, chiral liquid crystal, negative liquid crystal, terminal alkene liquid crystal, pyrimidine liquid crystal, fluorine-containing liquid crystal, alkyne liquid crystal, ethane liquid crystal and phenylcyclohexane liquid crystal.
The surface is attached with particles of nanometer-sized molecules, and the nanometer-sized molecules can have an achiral structure or a chiral structure, such as antigens, antibodies, enzymes, hormones, amines, peptides, amino acids, vitamins and the like.
The liquid crystal material substrate flat plate is realized by a material growth process, and comprises magnetron sputtering, electron beam evaporation, metal organic compound chemical vapor deposition, vapor phase epitaxial growth, molecular beam epitaxy and the like.
The substrate flat plate of the liquid crystal material can change the liquid crystal molecular axis direction of the liquid crystal material in the substrate flat plate through the modes of illumination, electrification, heating, pressurization and the like, and further change the birefringence and the dielectric coefficient of the liquid crystal material.
The system of the present invention consists of a light source, a microscope and an optical force display. Before testing, a liquid crystal material substrate flat plate is placed at the bottom of a sample pool filled with water or oil, then particles with nano-sized molecules attached to the surface are placed in the sample pool filled with water or oil and are placed above the liquid crystal material substrate flat plate, a linear polarization plane wave light source enters from the side wall of the sample pool to irradiate the particles, and as the liquid crystal material substrate flat plate destroys the symmetrical distribution of the boscalid vectors around the particles, the total boscalid vectors on the particles are not zero, and non-gradient optical force is generated; the direction of the liquid crystal molecular axis of the liquid crystal material is changed to change the birefringence and the dielectric coefficient of the liquid crystal material, so that the total boston vector distribution on the surface of the particles above the substrate flat plate of the liquid crystal material is changed, the direction and the size of the non-gradient optical force of the total boston vector acting on the particles are further changed, the motion trail of the particles in an incident light field is regulated and controlled, and the tunable capture and screening of the nano-sized molecules attached to the surfaces of the particles are further performed. The microscope can be used to observe the motion trail of the particles with nanometer-sized molecules attached on the surface under the action of incident light. The microscope may be a normal fluorescence vertical or upright microscope.
The system can realize tunable capture and screening of objects with nanometer-sized achiral structures through simple linearly polarized planar light waves. The method overcomes the problems that an incident light source is complex (namely, the incident light is required to be circularly polarized or elliptically polarized), a screening object is limited (namely, the nano-sized molecules are required to have chirality), the gradient optical force generated by circularly polarized light or elliptically polarized light is not tunable, the nano-sized molecules are difficult to capture and the like in the traditional method of capturing and screening the nano-sized molecules by utilizing the gradient optical force, has the advantages of simple system, convenience in operation, super sensitivity, super rapidness, active tuning and the like, and can be used in the fields of biology, medicine, nano control and the like.
Drawings
FIG. 1 is a schematic view of a microparticle having a nanosized molecule attached to the surface thereof.
Fig. 2 is a schematic diagram of a process of capturing and screening particles with nanometer-sized molecules attached on the surface above a liquid crystal material substrate flat plate by a non-gradient optical force generated by linearly polarized light.
Fig. 3 is a schematic diagram of a testing system for capturing and screening particles with nanometer-sized molecules attached on the surface above a liquid crystal material substrate flat plate by a non-gradient optical force generated by linearly polarized light.
In the figure: 1 particle, 2 nanometer size molecule, 3 liquid crystal material substrate flat plate, 4 light source, 5 microscope, 6 optical force display, 7 sample pool, 8 temperature controller, 9CCD camera, 10 monitor, 11 computer, 12 video recorder.
Detailed Description
In order to make the technical solution of the present invention clearer, the following describes in detail a specific embodiment of the present invention with reference to the technical solution and the accompanying drawings. The material growth technology comprises the following steps: magnetron sputtering, electron beam evaporation, chemical vapor deposition of metal organic compounds, vapor phase epitaxy, and molecular beam epitaxy.
Example 1
First, the particles 1 are produced by a material growth process, as shown in fig. 1 (a). The geometric shape and size of the particles can be determined by using algorithms such as a finite time domain difference method, a finite element method and the like.
Next, the nano-sized molecules 2 are attached to the outer surface of the fine particles 1, as shown in fig. 1 (b).
Then, the particles 1 with the nano-sized molecules 2 attached to the surface are placed above the surface of the liquid crystal material substrate plate 3 by a distance l (l > 0), when the incident light is a linearly polarized plane wave and the liquid crystal molecular axis of the liquid crystal material substrate plate 3 is consistent with the optical axis direction, the boston vectors around the particles 1 above the liquid crystal material substrate plate 3 are asymmetrically distributed, that is, the total boston vector on the particles 1 is not zero, a non-gradient optical force pointing to the right front along the incident light direction is generated, so that the particles 1 move along the right front along the incident light direction, and further the nano-sized molecules 2 attached to the surface of the particles 1 are driven to move along the right front along the incident light direction, as shown in fig. 2 (a).
Then, due to the anisotropy of the dielectric constant of the liquid crystal material, the liquid crystal molecular axis of the liquid crystal material substrate plate 3 can be made to face another direction (i.e. different from the optical axis direction) by means of illumination, electrification, heating, pressurization and the like, so that the direction and the magnitude of the total boston vector on the surface of the particle 1 are changed, a non-gradient optical force pointing to the left front direction along the incident light direction is generated, and the particle 1 drives the nano-sized molecules 2 attached to the surface thereof to move along the left front direction of the incident light direction, as shown in fig. 2 (b).
Finally, the liquid crystal molecular axis direction of the liquid crystal material substrate flat plate 3 is changed back to be consistent with the optical axis direction through cooling, illumination and other modes, at this time, the non-gradient optical force applied to the particles 1 is changed back to the non-gradient optical force pointing to the right front along the incident light direction, and the particles 1 drive the nanometer-sized molecules 2 to move along the right front along the incident light direction, as shown in fig. 2 (c).
Therefore, the movement track of the particles 1 in an incident light field is controlled by changing the axial direction of liquid crystal molecules in the liquid crystal material substrate flat plate 3, and finally tunable capture and screening of the nano-sized molecules 2 attached to the surfaces of the particles 1 are realized.
The system of the present invention is primarily comprised of a light source 4, a microscope 5 and an optical force display 6. Before testing, the liquid crystal material substrate flat plate 3 is placed at the bottom of a sample cell 7 filled with water or oil, and then the particles 1 with the nano-sized molecules 2 attached to the surface are placed in the sample cell 7 and are placed above the liquid crystal material substrate flat plate 3. The light source 4 generates linearly polarized plane waves which enter from the side wall of the sample cell 7 and horizontally irradiate the particles 1, so that the particles 1 with the nano-sized molecules 2 attached to the surface are captured and manipulated. The microscope 5 can be used to observe the motion trail of the particles 1 with the nanometer-sized molecules 2 attached to the micro-surface under the action of incident light. The non-gradient optical force generated by the particles 1 with the nano-sized molecules 2 attached to the surface of the linearly polarized plane wave is measured by the optical force display 6. The system of the invention also comprises a temperature controller 8, a CCD camera 9, a monitor 10, a computer 11, a video recorder 12 and the like (shown in figure 3). The particles 1 with the nanometer-sized molecules 2 attached to the surface under the irradiation of the linearly polarized plane waves are monitored in real time by using a CCD camera 9, and the obtained video signals are displayed on a display. The video recorder 12 can be used to record images. The sample cell 7 is connected to a temperature controller 8 so that the liquid crystal molecular axis direction of the liquid crystal material in the liquid crystal material substrate plate 3 changes with the temperature change of the sample cell 7. The computer 11 may store field of view information acquired by the microscope 5.
The foregoing is a technical principle and specific examples applied to the present invention, and equivalents made according to the idea of the present invention should be within the scope of the present invention as long as they are applied without departing from the spirit covered by the specification and the accompanying drawings.
Claims (7)
1. A method for capturing and screening particles above a liquid crystal material substrate in a tunable mode by linearly polarized planar light waves is characterized in that the particles are placed above a liquid crystal material substrate flat plate, the liquid crystal material substrate flat plate destroys the symmetrical distribution of the boscalid vectors around the particles, so that the total boscalid vector on the particles is not zero, and non-gradient optical force is generated; the method comprises the steps of changing the direction of the molecular axis of a liquid crystal material substrate flat plate, changing the distribution of total glass seal pavilion vectors on particles, further changing the direction and the size of non-gradient optical force of the total glass seal pavilion vectors acting on the particles, regulating and controlling the motion trail of the particles in an incident light field, and accordingly conducting tunable capture and screening on nano-sized molecules attached to the surfaces of the particles, wherein the particles are placed above the liquid crystal material substrate flat plate, the particle material is a medium or metal, the length, the width and the height of the liquid crystal material substrate are 10 nanometers to 10 meters, and the distance between the particles and the surfaces of the liquid crystal material substrate flat plate is l, wherein l is greater than 0; the shape of the particle is a curved surface geometry or polyhedron, and the volume is 1 cubic nanometer to 1000 cubic micrometers; the incident light is linearly polarized plane wave;
the direction of the liquid crystal molecular axis of the liquid crystal material is changed by illumination, electrification, heating and pressurization, and the birefringence and the dielectric coefficient of the liquid crystal material are further changed.
2. The method of claim 1, wherein the incident light is incident in a direction parallel to the plane of the substrate of liquid crystal material and has a frequency in the range of 0.3 to 20 microns and a power in the range of 0.1mW/μm 2 ～10mW/μm 2 。
3. The method according to claim 1 or 2, characterized in that the light source of the incident light is a wavelength tunable laser, a semiconductor continuous or quasi-continuous laser or a light emitting diode.
4. A method according to claim 3, characterized in that the particulate material is a metal or a medium, wherein the metal is Al, ag, au, cu, ni, pt and the medium is Si, siO 2 、GaAs、InP、Al 2 O 3 One kind of (1).
5. The method of claim 3, wherein the liquid crystal material is nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, discotic liquid crystal, thermotropic liquid crystal, reproducible liquid crystal, chiral liquid crystal, negative liquid crystal, terminated ene liquid crystal, pyrimidine liquid crystal, fluorine-containing liquid crystal, acetylene liquid crystal, ethane liquid crystal, phenylcyclohexane liquid crystal.
6. The method of claim 1 or 2 or 4, wherein the nanosized molecules have an achiral structure or a chiral structure.
7. A method as claimed in claim 1, 2 or 4, characterized in that the plate of the substrate of liquid crystal material is realized by a material growth process comprising magnetron sputtering, electron beam evaporation, chemical vapor deposition of metal organic compounds, vapor phase epitaxy, molecular beam epitaxy.
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| AU2003224907A1 (en) * | 2002-04-10 | 2003-10-27 | Arryx, Inc. | Apparatus and method to generate and control optical traps to manipulate small particles |
| JP2006235319A (en) * | 2005-02-25 | 2006-09-07 | Japan Science & Technology Agency | Device for controlling movement of particulate |
| JP5035798B2 (en) * | 2007-08-31 | 2012-09-26 | 国立大学法人秋田大学 | Fine particle light capture and rotation control device |
| CN103676126A (en) * | 2013-12-20 | 2014-03-26 | 同济大学 | Operation instrument for optical tweezers |
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