A method for capturing biological samples using continuous-domain quasi-bound-state terahertz metasurface tweezers

Abstract

The present invention discloses a method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers. The method comprises designing quasi-bound state-excited terahertz metasurface tweezers for the particles to be captured; dripping a solution containing the biological sample particles to be captured onto the surface of the designed metasurface tweezers; adjusting the relative angle between the metasurface tweezers and the polarization direction of the terahertz wave, irradiating the terahertz wave, and forming a localized electric field in a specific area of ​​the metasurface tweezers; utilizing the localized electric field to generate a capture potential well, and utilizing the gradient force generated by the potential well to capture the biological sample particles within the area. The present invention implements a quasi-bound state-excited terahertz metasurface tweezer in the terahertz band, capable of achieving very high electric field enhancement and localization, thereby improving the ability to non-destructively capture and manipulate biological sample particles.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz spectroscopy applications, and in particular relates to a method for capturing biological samples based on continuous-domain quasi-bound-state terahertz metasurface tweezers. Background Art

[0002] In the field of biomedicine, it is often necessary to capture and precisely manipulate the position of biological samples such as nano- and micron-sized molecules, viruses, and cells, such as by binding certain chemical molecules to specific cell receptors. The usual technical approach is to first modify and label the biological sample using fluorescent agents, radionuclides, and other substances, and then manually manipulate and transport it to a specific location. These methods are not only unable to achieve non-contact and may contaminate the biological sample, but the labeling process is relatively cumbersome, and it is difficult to accurately and efficiently capture and manipulate the target biological sample, which greatly limits researchers' research on the functional properties of microscopic biological samples.

[0003] Optical tweezers use laser beams to form a three-dimensional potential well to capture tiny particles. By changing the beam's focus, the particle's movement can be further manipulated, much like using light as tweezers to clamp the particle. However, traditional optical tweezers utilize high-energy laser beams, which not only have high energy and may directly or indirectly damage biological samples, but also have significant limitations on the size of particles they can manipulate due to the diffraction limit.

[0004] In recent years, researchers have realized metasurface tweezers with the help of subwavelength periodic structures based on plasma element resonance, and optical tweezers technology has rapidly expanded to the field of optoelectronics. When an electromagnetic wave is incident on the surface of a metasurface device, a large number of plasma elements will be generated at the interface between the metal and the medium. These elements oscillate back and forth, causing the incident electromagnetic wave to resonate strongly with the metasurface, thereby forming an electric field with a large gradient. The high-gradient electric field will produce a high three-dimensional potential well, which means that it will exert a large binding force on the acting particles. Metasurface tweezers break the limitation of traditional optical tweezers that require complex and precise optical equipment, overcome the limitation of the diffraction limit, and also solve the problem of excessive laser energy, which may cause potential harm to biological samples, and can accurately capture and manipulate smaller particles.

[0005] Although metasurface tweezers address the aforementioned shortcomings of traditional laser tweezers, a large number of existing metasurface tweezers use visible light and infrared waves, which may damage certain biological samples and therefore cannot achieve non-destructive capture and manipulation of these biological samples. In addition, in order to achieve higher capture force, it is necessary to enhance the electric field gradient or electric field localization on the device surface, while the electric field gradient and localization of existing metasurface tweezers still need to be improved. In short, these practical needs force us to seek a new metasurface tweezer technology that can improve capture force and achieve non-destructive manipulation of biological samples.

[0006] Secondly, traditional laser optical tweezers technology uses a high numerical aperture objective lens to focus the incident laser, and uses optical gradient force to form a three-dimensional potential well at the focal position to achieve non-contact capture of microparticles. However, the light intensity of the beam is too high, which will damage the biological sample. In addition, due to the diffraction limit of laser, the size of the microparticles that can be captured by optical tweezers using laser technology is generally in the micrometer scale, which further limits its application in the biomedical field. On the other hand, due to years of research and development of visible light and infrared waves, the related light sources, detectors and application devices have become very widespread and mature, but metasurface tweezers based on visible light or infrared waves will still face problems such as poor biocompatibility, making it difficult to achieve non-destructive capture and manipulation of different types of biological samples. Terahertz waves (electromagnetic waves with a frequency range of 0.1 to 10 THz, 1 THz = 1 × 10 12 Only in recent years have the two key technologies of terahertz sources and detection been gradually resolved and improved. Accordingly, terahertz-related devices and their applications are still under a research boom, especially the terahertz-band metasurface tweezers mentioned in this application, which still need to be developed and studied. Compared with lasers and infrared waves, terahertz waves have advantages such as low photon energy and good biocompatibility. However, if metasurface tweezers are directly designed and constructed in the terahertz band, the longer wavelength of terahertz waves (compared to infrared and visible light) will result in poor electric field enhancement and localization of the device, limiting its ability to capture and manipulate biological samples. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers. The method utilizes terahertz waves instead of lasers, visible light or infrared, has a very high biocompatibility, and does not cause damage to biological samples. By using metasurface tweezers based on continuous domain quasi-bound state to improve the localization and enhancement capabilities of the electric field, the disadvantage of low electric field localization of terahertz wave devices is improved, the binding force that can be provided for capturing particles is increased, and thus the capture capability is improved.

[0008] The present invention adopts the following technical solutions:

[0009] The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers comprises the following steps:

[0010] S1. Design of terahertz metasurface tweezers for quasi-bound state excitation of particles to be captured;

[0011] S2, dropping a solution containing the biological sample particles to be captured onto the surface of the metasurface tweezers designed in step S1;

[0012] S3, adjusting the relative angle between the metasurface tweezers and the polarization direction of the terahertz wave, irradiating the terahertz wave to form the maximum local enhancement of the electric field on the metasurface tweezers;

[0013] S4. Using the maximum electric field enhanced in step S3 to locally generate a capture potential well, the biological sample particles are captured by the gradient force generated by the capture potential well.

[0014] Specifically, in step S1, the unit period size of the terahertz metasurface tweezers is 30 μm to 3 mm.

[0015] Furthermore, the terahertz metasurface tweezers include several metasurface minimum unit structures, which are periodically arrayed in a plane. The relative dielectric constant of the metasurface minimum unit structure is 11.8 to 12, and the electrical conductivity of the metal is 4.56×10 7 ~5.8×10 7 S / m.

[0016] Furthermore, the minimum unit structure of the metasurface includes a substrate and a vertical bar structure. The vertical bar structure is arranged on the substrate, the length of the substrate is P = 85~95μm, and the height is H = 35~50μm; the vertical bar structure is a rectangular structure, including a first vertical bar structure and a second vertical bar structure arranged at intervals, the length of the first vertical bar structure is L = 50μm, the width is W = 30~35μm, and the height is H = 35~50μm, the length of the second vertical bar structure is L+ΔL, L = 50μm, ΔL = -30~30μm, the width is W = 30~35μm, and the height is H = 35~50μm.

[0017] Furthermore, the length of the base is P = 240 ~ 260 μm, and the height is H = 20 ~ 25 μm; the vertical bar structure is a cube structure, the length of the cube structure is S = 140 ~ 160 μm, and there is a hole on the cube structure, the length of the hole is L = 35 ~ 45 μm, the width is W = 40 ~ 50 μm, and the distance ΔY between the center of the hole and the center line of the cube structure is -50 ~ 50 μm.

[0018] Specifically, in step S2, the particle size of the biological sample particles to be captured is 10 nm to 10 μm.

[0019] Specifically, in step S3, the relative angle between the metasurface tweezers and the terahertz polarization direction is adjusted in a range of 0 to 180°, with an error of 0 to 5°.

[0020] Specifically, in step S3, the terahertz wave with an irradiation frequency of 0.1 to 5 THz and a spot size of 2 to 3 mm2 is used.

[0021] Furthermore, the maximum local electric field enhancement factor is 30 to 50 times.

[0022] Specifically, in step S4, the gradient force generated by the capture potential well is greater than or equal to 10k B T, k B is the Boltzmann constant, and T is the operating temperature.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] The present invention is based on a method for capturing biological samples using terahertz metasurface tweezers in a continuous domain quasi-bound state. By breaking the C2 symmetry, a metasurface tweezers capable of capturing particles of a desired size is designed. Since the designed metasurface device is polarization-sensitive, it is necessary to ensure that the polarization direction of the actual incident electromagnetic wave is consistent with the incident direction during simulation calculation during use, so as to maximize the electric field localization and enhancement effect. Due to the unique electromagnetic field localization characteristics of the quasi-bound state, the problem of low electric field localization of the terahertz metasurface tweezers can be effectively solved, thereby enhancing the gradient force and improving the ability to capture biological samples. In actual operation, the terahertz wave is first irradiated on the terahertz metasurface tweezers, so that the metasurface tweezers form a series of areas with relatively high electric field localization. At this time, the added biological sample particles will be captured in these areas.

[0025] Furthermore, the corresponding range of terahertz wave wavelength is 30μm to 3mm, and the size of the metasurface tweezers unit should be in the subwavelength order, that is, the unit period size is smaller than the wavelength corresponding to the resonant frequency. According to experience, the unit size is generally set at 50μm to 400μm.

[0026] Furthermore, the minimum unit structure of the metasurface is periodically arrayed in the plane. The array method can be found in Figure 3 In order to simplify the material setting, an all-silicon structure is selected, and the relative dielectric constant of silicon is 11.8~12.

[0027] Furthermore, the purpose of setting up a pair of cuboids is to fix the position of one of the cuboids and change the length (ΔL) of the other cuboid, so as to break the C2 symmetry and obtain a quasi-bound terahertz metasurface tweezers.

[0028] Furthermore, when the center of the cuboid coincides with the center of the hole, it has C2 symmetry. By adjusting the position of the hole (ΔY), the C2 symmetry is broken, thereby obtaining a quasi-bound terahertz metasurface tweezers.

[0029] Furthermore, metasurface tweezers are used to capture biological sample particles.

[0030] Furthermore, when the angle of the incident polarization direction is different from the design, the electromagnetic response will be different from the design result. In order to ensure that the device can achieve the designed effect, the actual polarization angle of the incident electromagnetic wave should be as small as possible from the theoretical simulation angle, generally within 5°.

[0031] Furthermore, the terahertz wave with an irradiation frequency of 0.1 to 5 THz and a spot size of 2 to 3 square millimeters meets the relevant parameters of terahertz equipment on the market.

[0032] Furthermore, specific areas refer to areas where the local enhancement of the electric field is very high. These areas have high electric field strength and will produce greater gradient forces. The particles will then be trapped in these areas.

[0033] Furthermore, the potential energy of the capture well is a key indicator for judging whether the particle can be captured. The potential energy at point r0 is calculated as In order to improve the ability to capture particles, it is necessary to increase the localization of the electric field, obtain a larger gradient force, and ultimately obtain a potential well that meets the requirements.

[0034] In summary, the present invention realizes a terahertz metasurface tweezers with quasi-bound state excitation in the terahertz band, which can achieve very high electric field enhancement and localization, so as to improve the ability to non-destructively capture and manipulate biological sample particles.

[0035] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The step of capturing biological samples by the metasurface tweezers of this application;

[0037] Figure 2 This is a unit model structure diagram of Example 1;

[0038] Figure 3 1 is a diagram showing the relationship between the unit structure and the overall metasurface tweezers of Example 1;

[0039] Figure 4 Contour plot of reflectance spectrum for different ΔL values ​​in Example 1;

[0040] Figure 5 This is a graph showing how the quality factor Q changes with ΔL in Example 1;

[0041] Figure 6 This is the electric field enhancement distribution diagram of Example 1 at ΔL=8μm and 1.1004THz;

[0042] Figure 7 Schematic diagram of the unit model structure of Example 2;

[0043] Figure 8 The absorption spectrum contour map of Example 2 at different ΔY;

[0044] Figure 9 is a graph showing the change of the quality factor Q with ΔY in Example 2;

[0045] Figure 10 This is the electric field enhancement distribution diagram of Example 2 at ΔY=30μm and 2.9221THz.

[0046] Among them, 1. Base; 2. Vertical bar structure. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," "one side," "one end," and "one side" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, in the description of the present invention, unless otherwise specified, "a plurality" means two or more.

[0049] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0050] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0051] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0052] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0053] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0054] The concept of bounded states in the continuum (BIC) originated in the field of quantum mechanics and was later extended to the field of optoelectronics. Bound states in the continuum cannot radiate energy outward, and the energy of electromagnetic waves is bound inside the structure. Therefore, the ideal bound state cannot be observed through experimental equipment. By breaking the C2 symmetry of the metasurface structure (C2 symmetry also refers to antisymmetry. When a certain geometric shape rotates 180 degrees around a certain axis and can coincide with the original shape, the geometric shape is said to have C2 symmetry), the ideal bound state becomes a quasi-bound state. Compared with the ideal bound state, the quasi-bound state has an observable linewidth (high quality factor Q) and can achieve strong electromagnetic field localization and enhancement. Its Q value and electromagnetic field localization and enhancement effect can be continuously controlled by the asymmetric coefficient.

[0055] Gradient force F grad The relationship between the electric field E is:

[0056]

[0057] The potential energy U0(r0) of the potential well at r0 can be calculated as:

[0058]

[0059] in, It represents gradient operation. To increase the potential energy, the gradient force needs to be increased. To increase the gradient force (capture force), this can be achieved by increasing the localization of the electric field or increasing the amplitude of the electric field.

[0060] The present invention provides a method for capturing biological samples using terahertz metasurface tweezers in a continuous domain with quasi-bound states. By breaking the C2 symmetry of the metasurface unit structure (when a certain geometric shape can overlap with the original shape after rotating 180 degrees around a certain axis, the geometric shape is said to have C2 symmetry), the unobservable bound state in the continuous domain is converted into an observable quasi-bound state, the localization and enhancement effect of the electric field are improved, and the capture capability of the metasurface tweezers is enhanced.

[0061] The present invention provides a method for capturing biological samples using a terahertz metasurface tweezers device based on a continuous domain quasi-bound state. The method aims to improve the electric field localization and enhancement of the terahertz metasurface tweezers through quasi-bound state resonance, thereby achieving stable capture and manipulation of biological samples. The specific steps are as follows:

[0062] S1. Design and manufacture terahertz metasurface tweezers with unit sizes of 30μm to 3mm and quasi-bound state excitation according to the approximate size of the particles to be captured;

[0063] The size of the particles to be captured is an order of magnitude smaller than the size of the smallest unit of the metasurface tweezers.

[0064] The present invention provides a terahertz metasurface tweezers based on a continuous domain quasi-bound state, comprising a plurality of metasurface minimum unit structures, which are periodically arrayed in a plane, with intervals between two adjacent metasurface minimum unit structures. The structure has no C2 symmetry in the plane and can achieve quasi-bound state excitation in the terahertz band. The metasurface minimum unit structure comprises a substrate 1 and a vertical stripe structure 2, wherein the substrate 1 is both the substrate of the entire device and a component of the device itself, and the vertical stripe structure 2 is arranged on the substrate 1.

[0065] Preferably, the relative dielectric constant of the minimum unit structure of the metasurface is 11.8 to 12, and the electrical conductivity of the metal is 4.56×10 7 ~5.8×10 7 S / m.

[0066] Metasurface tweezers use one or more combinations of dielectrics or metals. Commonly used dielectrics include silicon, silicon dioxide, resin, PDMS, etc., and commonly used metals include gold, silver, copper, titanium and chromium.

[0067] See also Figure 2 The length of the substrate 1 is P = 85 ~ 95 μm, and the height is H = 35 ~ 50 μm; the vertical bar structure 2 is a rectangular structure, including a first vertical bar structure and a second vertical bar structure, the length of the first vertical bar structure is L = 50 μm, the width is W = 30 ~ 35 μm, and the height is H = 35 ~ 50 μm, the length of the second vertical bar structure is L + ΔL, L = 50 μm, ΔL = -30 ~ 30 μm, the width is W = 30 ~ 35 μm, and the height is H = 35 ~ 50 μm; the vertical bar structure and the substrate are both made of silicon material.

[0068] See also Figure 7 The length of the substrate 1 is P = 240 ~ 260 μm, and the height is H = 20 ~ 25 μm; the minimum unit structure 2 of the super surface is a cube structure, the length of the cube structure is S = 140 ~ 160 μm, and there is a hole on the cube structure, the length of the hole is L = 35 ~ 45 μm, the width is W = 40 ~ 50 μm, and the distance ΔY between the center of the hole and the center line of the cube structure is -50 ~ 50 μm. The minimum unit structure of the super surface and the substrate are both made of gold.

[0069] S2, dropping a solution containing the biological sample particles to be captured onto the surface of the metasurface tweezers designed in step S1;

[0070] S3. Adjust the relative angle between the metasurface tweezers and the polarization direction of the terahertz wave (angle range is 0-180 degrees). When the amplitude of the resonance peak is the largest, the metasurface tweezers can have the best electromagnetic wave response. In this case, when irradiated with terahertz waves, the maximum electric field in a specific area of ​​the metasurface tweezers is locally enhanced by 30-50 times.

[0071] S4, the local electric field will generate potential energy greater than 10k B The biological sample particles will be captured in the region by the gradient force generated by the potential well.

[0072] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0073] Example 1

[0074] See also Figure 2 , is the unit geometry model of Example 1, consisting of two vertical bars and a rectangular base. All component materials are made of silicon with a dielectric constant of 11.9. This is the smallest unit, and a periodic array is formed in the plane to obtain a quasi-bound state enhanced terahertz metasurface tweezers (see Figure 3 ), in actual operation, the area of ​​the metasurface tweezers must at least be larger than the terahertz spot area (2 square millimeters). Taking processing issues into consideration, the number of arrays is 15*15 to 50*50.

[0075] The geometric dimensions of the terahertz metasurface tweezers range from P = 85 to 95 μm, H = 35 to 50 μm, W = 30 to 35 μm, L = 50 μm, and ΔL = -30 to 30 μm. Using CST Studio Suite electromagnetic simulation software, the reflection spectra of the incident electromagnetic wave with the polarization direction parallel to the vertical stripe direction (from -30 to 30 μm) are calculated within the range of 1.095 to 1.115 THz. Figure 4 As shown in , when ΔL approaches 0, the reflection spectrum gradually disappears, and the corresponding Q value is as follows: Figure 5 As shown in Figure 2, when the absolute value of ΔL becomes smaller, the Q value gradually increases. Based on the above two characteristics, it can be seen that there is an obvious bound state when ΔL = 0.

[0076] Preferably, P=90 μm, H=50 μm, W=30 μm, L=50 μm, and ΔL=8 μm are taken as the metasurface tweezers of Example 1.

[0077] See also Figure 6 For the preferred quasi-bound terahertz metasurface tweezers (ΔL=8μm), when the frequency is 1.1004THz, the electric field forms a high localization and enhancement at the two ends of the two vertical strips. The highest value reached was 5540. When a solution containing biological samples was added, the biological samples would be affected by the gradient force generated by the electric field and thus captured at both ends of the vertical bars.

[0078] See also Figure 4 , is the contour map of the reflection spectrum for different ΔL values, from Figure 4 It can be seen that when |ΔL| decreases, the width of the transmission spectrum resonance peak continues to decrease. At least when it reaches the bound state (|ΔL| = 0), the resonance peak width is too small to be observed. At this time, it theoretically has an infinite quality factor Q.

[0079] See also Figure 5 , is the change in the value of the quality factor Q under different ΔL values.

[0080] One of the quasi-bound states (P = 90 μm, H = 50 μm, W = 30 μm, L = 50 μm, ΔL = 8 μm) is selected as an example to calculate the electric field enhancement effect at a frequency of 1.1004 THz. Figure 6 , we can see that at both ends of the vertical strip, very high electric field enhancement and electric field localization are formed. The highest value reached was 5540. When a solution containing biological samples was added, the biological samples would be affected by the gradient force generated by the electric field and thus captured at both ends of the vertical bars.

[0081] Example 2

[0082] See also Figure 7 , is a schematic diagram of the unit structure of Example 2, which is shaped like a hole-punched square and is made of gold; the geometric dimensions range as follows: P = 240 ~ 260 μm, H = 20 ~ 25 μm, S = 140 ~ 160 μm, W = 40 ~ 50 μm, L = 35 ~ 45 μm, ΔY = -50 ~ 50 μm.

[0083] See also Figure 8 , Figure 8 The absorption spectrum contour plots are shown for the frequency range from 2.9 to 2.935 THz and ΔY from -50 to 50 μm.

[0084] See also Figure 9 , which is the corresponding Q value. When ΔY = 0, it is an obvious bound state excitation point.

[0085] Preferably, the dimensions P=250 μm, H=20 μm, S=150 μm, W=44 μm, L=40 μm, and ΔY=30 μm are taken as the terahertz metasurface tweezers of Example 2.

[0086] See also Figure 10 For the preferred quasi-bound terahertz metasurface tweezers (ΔY = 30 μm), when the resonant frequency is 2.9221 THz, the electric field forms a relatively high electric field localization and enhancement around the rectangle and inside the square hole, especially at the corners of the rectangle. The enhancement factor is It reached a maximum of 170 times and has a high ability to capture biological samples.

[0087] In summary, the present invention provides a method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers. By breaking the C2 symmetry, the bound state is converted into a quasi-bound state, and terahertz metasurface tweezers are constructed. The maximum electric field intensity enhancement reaches at least 70 times, which can be effectively used for the capture and manipulation of biological sample particles.

[0088] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers, characterized in that: The following steps are involved: S1. Design terahertz metasurface tweezers for quasi-bound state excitation for the captured particles. The unit period size of the terahertz metasurface tweezers is 30μm~3mm. The terahertz metasurface tweezers includes several metasurface minimum unit structures, which are arranged in a periodic array in the plane. The relative dielectric constant of the metasurface minimum unit structure is 11.8~12, and the conductivity of the metal is The minimum unit structure of the metasurface includes a substrate and a vertical stripe structure. The vertical stripe structure is set on the substrate. The length of the substrate is ,high ; The vertical bar structure is a rectangular parallelepiped structure, including a first vertical bar structure and a second vertical bar structure arranged at intervals, and the length of the first vertical bar structure is ,width ,high , the length of the second vertical bar structure is , , ,width ,high ; S2, dropping a solution containing the biological sample particles to be captured onto the surface of the metasurface tweezers designed in step S1; S3, adjusting the relative angle between the metasurface tweezers and the polarization direction of the terahertz wave, irradiating the terahertz wave to form the maximum local enhancement of the electric field on the metasurface tweezers; S4. Using the maximum electric field enhanced in step S3 to locally generate a capture potential well, the biological sample particles are captured by the gradient force generated by the capture potential well.

2. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 1, characterized in that: Length of base ,high ; The vertical bar structure is a cube structure, and the length of the cube structure , there is a hole in the cube structure, the length of the hole ,width , the distance between the hole center and the center line of the cube structure .

3. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 1, characterized in that: In step S2, the particle size of the biological sample particles to be captured is 10 nm to 10 μm.

4. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 1, characterized in that: In step S3, the relative angle between the metasurface tweezers and the terahertz polarization direction is adjusted in the range of 0 to 180°, with an error of 0 to 5°.

5. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 1, characterized in that: In step S3, the irradiation frequency is 0.1~5THz and the spot size is 2~3mm 2 of terahertz waves.

6. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 5, characterized in that: The maximum local electric field enhancement factor is 30 to 50 times.

7. The method for capturing biological samples based on continuous domain quasi-bound state terahertz metasurface tweezers according to claim 1, characterized in that: In step S4, the gradient force generated by the trapping potential well is greater than or equal to 10 , is the Boltzmann constant, T For the operating temperature.

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