Asymmetric hollow cylindrical metasurface terahertz biosensor and method thereof

Abstract

The application discloses a kind of based on asymmetric hollow cylindrical metasurface terahertz biosensor and method thereof.The sensor is obtained by periodic arrangement by metasurface unit;Each metasurface unit is composed of dielectric substrate and hollow cylindrical array unit.The application introduces asymmetric disturbance by asymmetric arrangement of four hollow cylindrical array units of hollow cylindrical body, and induces terahertz wave to form quasi-continuous body bound state (Q-BIC) resonance peak with super-high Q value on it, realizes Q value up to 20000 or more using quasi-continuous domain bound state induction mechanism, can produce obvious response signal in terahertz spectrum, so as to realize the super-sensitive detection of trace biological substance, greatly improve detection efficiency and accuracy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of terahertz sensors, and particularly relates to a kind of based on asymmetric hollow cylinder super surface terahertz biological sensor and method thereof. BACKGROUND

[0002] As a new type of optical detection technology, terahertz has been widely used in the field of biomedicine due to its low photon energy, strong penetration and other characteristics. The fingerprint frequency of biological substances in the terahertz band provides a new platform for the qualitative and quantitative detection of biological macromolecules (including DNA, RNA, amino acids and proteins, etc.). However, the intermolecular or intramolecular vibration of biological analytes in the terahertz region is very weak, which seriously limits the development of terahertz technology in biological detection applications. Traditional terahertz super surface sensors are mainly divided into two categories: metal surface plasmon resonance (SPR) biosensors and dielectric guided mode resonance (GMR) biosensors. The Q value of SPR sensor is limited due to metal loss, making it difficult to improve the figure of merit (FoM) defined by the ratio of sensitivity to full width at half maximum (FWHM); while the electromagnetic field of GMR sensor is confined inside the structure, resulting in reduced sensitivity to external refractive index changes. In recent years, the principle of bound state in the continuum (QBIC) in the continuous domain breaks through the traditional wave bound mechanism. Its frequency exists in the continuous spectrum, but has an infinite high Q factor. By breaking the in-plane symmetry of the structure, the unobservable bound state is transformed into a high-Q quasi-continuous domain bound state, which can enhance the interaction between light and matter and achieve local field enhancement. Quasi-continuous domain bound state has attracted widespread attention due to its precise control of resonance wavelength, Q value and near-field localization capability. QBIC super surface sensor has high Q value and avoids the problems of material dispersion and absorption of SPR sensor and excessive localization of electromagnetic field of GMR sensor, providing a new and feasible way for ultra-sensitive biomedical sensing and detection.

[0003] Since the existing terahertz sensors are based on traditional resonance mechanism, the Q value in the terahertz band is generally low, in the range of tens to hundreds, and it is difficult to further improve the Q value. On the other hand, in order to pursue a higher Q value, the processing precision is limited to within nanometers, which makes the processing technology more difficult and the cost higher, which greatly limits its commercial application. Quasi-continuous body bound state (Q-BIC) can be excited by introducing perturbation, i.e. changing the key parameter size of the super surface resonator, to destroy its structural symmetry. The resulting leaky resonance mode will be coupled to the free space, and it can be observed in the far field. The Q value of Q-BIC resonance peak can easily reach hundreds, so it has great application potential in the detection of biological samples at very low concentration. SUMMARY

[0004] The application aims to solve the problem of low detection sensitivity of traditional terahertz detection technology for biological samples and provide a non-symmetrical hollow cylindrical metasurface terahertz biosensor and a method thereof.

[0005] The specific technical scheme adopted by the application is as follows:

[0006] In a first aspect, the application provides a non-symmetrical hollow cylindrical metasurface terahertz biosensor, which is obtained by periodic arrangement of metasurface units. Each metasurface unit is composed of a dielectric substrate and a hollow cylindrical array unit. The hollow cylindrical array unit is composed of four hollow lithium titanate cylinders vertically arranged on the upper surface of the dielectric substrate, including two identical first hollow cylinders and two identical second hollow cylinders. The inner radius of the cross section of the first hollow cylinder is the same as that of the second hollow cylinder, the outer radius of the cross section of the first hollow cylinder is smaller than that of the second hollow cylinder, and the four hollow cylinders have the same height. The non-symmetrical arrangement is formed by the difference in outer radius, thereby introducing non-symmetrical disturbance.

[0007] As a preferred embodiment of the first aspect, the inner radius of the cross section of the first hollow cylinder is 7-9 μm, and the outer radius is 9-10 μm; the inner radius of the cross section of the second hollow cylinder is 7-9 μm, and the outer radius is 10-10.5 μm.

[0008] As a preferred embodiment of the first aspect, the inner radius of the cross section of the first hollow cylinder is 8 μm, and the outer radius is 10 μm; the inner radius of the cross section of the second hollow cylinder is 8 μm, and the outer radius is 10.1 μm.

[0009] As a preferred embodiment of the first aspect, the intersection of the axis of the four hollow cylinders in the hollow cylindrical array unit and the surface of the dielectric substrate is located at the four corner points of a square, the two corner points corresponding to the two first hollow cylinders belong to one side of the square, the two corner points corresponding to the two second hollow cylinders belong to the other side of the square, and the side length of the square is 25-28 μm.

[0010] As a preferred embodiment of the first aspect, the side length of the square is 27 μm.

[0011] As a preferred embodiment of the first aspect, the material of the dielectric substrate is silicon, quartz or polyimide, and the thickness is 30-33 μm.

[0012] As a preferred embodiment of the first aspect, the unit period of the metasurface unit is 57-60 μm.

[0013] As the preferred of the first aspect, the height of the four hollow cylinders in the hollow cylinder array unit is 9-12 μm.

[0014] In the second aspect, the present application provides a method for detecting the content of a biological sample component, which is implemented by fixing the asymmetric hollow lithium cylinder super surface terahertz biosensor according to any one of the first aspect above in the optical path of a terahertz wave detection system, vertically irradiating the terahertz wave from one side of the hollow cylinder array unit, detecting and recording the transmission spectrum of the terahertz biosensor without adding a sample solution, then dropping the biological sample solution to be detected on the surface of the terahertz biosensor and drying it into a film, detecting and recording the transmission spectrum of the terahertz biosensor, extracting the Q-BIC resonance peak from the terahertz wave transmission spectrum before and after the sample solution is added respectively and calculating the frequency shift or amplitude change, and obtaining the content of the target component in the biological sample solution to be detected through the conversion model fitted in advance for the target component.

[0015] As the preferred of the second aspect, the conversion model adopts a linear model, the dependent variable of which is the frequency shift or amplitude change, and the independent variable of which is the volume percentage of the target component.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The present application provides an asymmetric lithium titanate hollow cylinder super surface terahertz biosensor, which introduces an asymmetric disturbance by configuring the size and relative position of the four hollow cylinder array super surface units in the terahertz biosensor, induces a quasi-continuum bound state (Q-BIC) of terahertz waves in the terahertz wave band, realizes a Q-BIC resonance peak with a quality factor (Q value) of 20000 or more, and produces a clear response signal in the terahertz spectrum. This high-sensitivity resonance peak can realize super-sensitive detection of trace and trace biological sample molecules, greatly improve the detection efficiency and accuracy, and provide a new and simple design approach for the design and development of terahertz high-sensitivity sensors. The present application has good multiplexing, mature processing technology, low production cost, and good commercial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Fig. 1 is a structural schematic diagram of the asymmetric lithium hollow cylinder super surface terahertz biosensor and the periodic unit according to the present application;

[0019] Figure 2 Fig. 2 is a top view of the middle periodic unit structure; Figure 1

[0020] Figure 3 ​Terahertz wave (a) transmission spectrum and (b) transmission curve of the sensor device in the embodiment of the present application when the unit structure asymmetry parameter Δr = r1-r0 of the sensor device in the embodiment of the present application varies from 0 μm to 0.8 μm;

[0021] Figure 4 Terahertz wave transmission curve (a) corresponding to the unit structure asymmetry parameter Δr = 0.1 μm of the sensor device in the embodiment of the present application, variation trend of Q factor when the unit structure asymmetry degree α = (r1-r0) / r1 varies in the range of 0.009~0.08 (b), and |E| field intensity distribution of the sensor QBIC when the unit structure asymmetry degree α = 0.029 (c);

[0022] Figure 5 Multipole scattering power spectrum of the sensor device in the embodiment of the present application in TD1 and Q-BIC resonance modes;

[0023] Figure 6 Structure top view magnetic field diagram (a) and structure side view magnetic field diagram (b) of the sensor device in the embodiment of the present application in TD1 mode, wherein the black arrow represents displacement current and the white arrow represents magnetic field vector;

[0024] Figure 7 Structure top view magnetic field diagram (a) and structure side view magnetic field diagram (b) of the sensor device in the embodiment of the present application in Q-BIC mode, wherein the black arrow represents displacement current and the white arrow represents magnetic field vector;

[0025] Figure 8 Relationship of terahertz wave transmission curve of the sensor device in the embodiment of the present application with different unit structure parameters, wherein (a) is different period P, (b) is different hollow cylindrical hole spacing L, (c) is different substrate thickness H, and (d) is different hollow cylindrical height h;

[0026] Figure 9 Relationship of frequency shift of Q-BIC resonance peak of the sensor device in the embodiment of the present application with variation of quality factor, wherein (a) is relationship of frequency shift of Q-BIC resonance peak with variation of thickness of the measured object (refractive index n = 1.5), (b) is relationship of frequency shift of Q-BIC resonance peak with variation of different measured objects (refractive index), and (c) is relationship of resonance quality factor of QBIC with variation of different measured objects (refractive index). DETAILED DESCRIPTION

[0027] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in various embodiments of the present invention can be combined accordingly without mutual conflict.

[0028] In the description of this invention, it should be understood that when an element is considered to be "connected" to another element, it can be a direct connection to the other element or an indirect connection, i.e., there is an intermediate element. Conversely, when an element is said to be "directly" connected to another element, there is no intermediate element.

[0029] In the description of this invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0030] like Figure 1 As shown, in a preferred embodiment of the present invention, a terahertz biosensor based on an asymmetric hollow cylindrical metasurface is provided. The metasurface of the sensor is obtained by periodically arranging metasurface units 1. Each metasurface unit 1 consists of a dielectric substrate 2 and a hollow cylindrical array unit disposed on the dielectric substrate 2. The hollow cylindrical array unit consists of four hollow cylinders perpendicularly disposed on the upper surface of the dielectric substrate 2. The cross-section of each of the four hollow cylinders is annular, and the material used is lithium titanate (LiTaO3) with a relative permittivity of 41.4. The hollow cylindrical array unit comprises four hollow cylinders, including two identical first hollow cylinders 3 and two identical second hollow cylinders 4. The first hollow cylinders 3 are small-radius hollow cylinders, while the second hollow cylinders 4 are large-radius hollow cylinders. Specifically, the inner radius of the cross-section of the first hollow cylinder 3 is the same as that of the second hollow cylinder 4, while the outer radius of the cross-section of the first hollow cylinder 3 is smaller than that of the second hollow cylinder 4. All four hollow cylinders have the same height. Therefore, the four hollow cylinders in the hollow cylindrical array unit differ only in their outer cross-sectional radii; all other structural dimensions are identical. Thus, this metasurface unit 1, with its four hollow cylinders arranged asymmetrically through the difference in outer radii, introduces asymmetrical perturbations and induces terahertz waves to form quasi-continuum bound-state resonance peaks with ultra-high Q values, enabling ultrasensitive sample detection.

[0031] It should be noted that although the entire metasurface can be regarded as a combination of a series of metasurface units 1, it is actually manufactured as a whole and there is no physical boundary.

[0032] like Figure 2 As shown, for ease of description, the inner radius of the cross-section of the first hollow cylinder 3 is denoted as r, the outer radius as r0, and the distance between the axes of the two first hollow cylinders 3 is denoted as L. The inner radius of the cross-section of the second hollow cylinder 4 is denoted as r, the outer radius as r1, and the distance between the axes of the two second hollow cylinders 4 is denoted as L. The period of the metasurface unit 1 is denoted as P. The first hollow cylinder 3 and the second hollow cylinder 4 must satisfy r1 > r0. Therefore, the present invention can define the asymmetry parameter Δr of the unit structure as the difference between the two inner radii, that is, Δr = r1 - r0, and Δr > 0.

[0033] The parameters of each of the above components can be optimized according to actual needs, specifically based on whether the final device performance meets the usage requirements. In the embodiments of the present invention, the preferred parameters of each component are as follows:

[0034] The first hollow cylinder 3 has an inner radius r of 7~9 μm and an outer radius r0 of 9~10 μm; the second hollow cylinder 4 has an inner radius r of 7~9 μm and an outer radius r1 of 10~10.5 μm. More preferably, the first hollow cylinder 3 has an inner radius r of 8 μm and an outer radius r0 of 10 μm; the second hollow cylinder 4 has an inner radius r of 8 μm and an outer radius r1 of 10.1 μm. Furthermore, the intersections of the axes of the four hollow cylinders in the hollow cylinder array unit with the surface of the dielectric substrate 2 are located at the four corner points of a square. The two corner points corresponding to the two first hollow cylinders 3 belong to one side of the square, and the two corner points corresponding to the two second hollow cylinders 4 belong to the other side of the square. The square is located at the center of the dielectric substrate 2, and the side length L of the square is 25~28 μm, with a further side length of μm. The dielectric substrate 2 is made of materials including but not limited to silicon, quartz, or polyimide, and its thickness is preferably 30-33 μm. The cell period P of the metasurface unit 1 is preferably 57-60 μm. The height of the four hollow cylinders in the hollow cylinder array unit is preferably 9-12 μm.

[0035] In the embodiment of the present application, on the basis of the above-mentioned asymmetric hollow cylindrical metasurface terahertz biosensor, it can be further combined in the optical path of the terahertz wave detection system, and then a biological sample component content detection method is realized. The specific method is as follows: the above-mentioned asymmetric hollow cylindrical metasurface terahertz biosensor is installed in the optical path of the terahertz wave detection system, the terahertz wave is vertically incident from one side of the hollow cylindrical array unit, and the terahertz wave projection spectrum is detected from the back of the terahertz biosensor. During detection, first, the transmission spectrum of the terahertz biosensor is detected and recorded without adding a sample solution, then the biological sample solution to be measured is dropped on the surface of the terahertz biosensor and dried into a film, the transmission spectrum of the terahertz biosensor is detected and recorded, the Q-BIC resonance peaks are extracted from the two groups of terahertz wave transmission spectra before and after the sample solution is added, and the frequency shift or amplitude change between the two Q-BIC resonance peaks is calculated, and the content of the target component in the biological sample solution to be measured is obtained by the conversion model fitted in advance for the target component.

[0036] It should be noted that the conversion model adopts a linear model, which is y = -ax + b, where the dependent variable y is the frequency shift or amplitude change, and the independent variable x is the volume percentage of the target component. The coefficients a and b in the linear model can be calibrated by using standard solutions containing different volume percentages of target components in advance. Based on the coefficients a and b obtained by calibration, the linear model can be used to calculate the content of the target component in the biological sample solution to be measured according to the actually measured frequency shift or amplitude change.

[0037] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with embodiments.

[0038] Embodiment

[0039] The specific structure of the sensor device as a whole and the periodic unit 1 in the asymmetric lithium titanate hollow cylindrical metasurface terahertz biosensor proposed in this embodiment is as follows: Figure 1As shown, the device is formed by a series of metasurface units 1 on a plane by periodic arrangement to form a continuous metasurface. Each metasurface unit 1 is composed of a dielectric substrate 2 and a hollow cylindrical array unit. The hollow cylindrical array unit is composed of four hollow cylindrical bodies made of lithium titanate vertically arranged on the upper surface of the dielectric substrate 2. The dielectric substrate 2 adopts a quartz substrate, and the bottom surfaces of the four hollow cylindrical bodies are in contact with the quartz substrate. The hollow cylindrical array unit contains two identical first hollow cylindrical bodies 3 and two identical second hollow cylindrical bodies 4, both made of lithium titanate (LiTaO3) with a relative dielectric constant of 41.4. The intersection of the axes of the four hollow cylindrical bodies in the hollow cylindrical array unit and the surface of the dielectric substrate 2 is at the four corner points of the square. Therefore, the spacing between the two adjacent first hollow cylindrical bodies 3, the spacing between the two adjacent second hollow cylindrical bodies 4, and the spacing between the adjacent first hollow cylindrical body 3 and the second hollow cylindrical body 4 all correspond to the side length L of the square. Figure 2 As shown, the device is formed by a series of metasurface units 1 on a plane by periodic arrangement to form a continuous metasurface. Each metasurface unit 1 is composed of a dielectric substrate 2 and a hollow cylindrical array unit. The hollow cylindrical array unit is composed of four hollow cylindrical bodies made of lithium titanate vertically arranged on the upper surface of the dielectric substrate 2. The dielectric substrate 2 adopts a quartz substrate, and the bottom surfaces of the four hollow cylindrical bodies are in contact with the quartz substrate. The hollow cylindrical array unit contains two identical first hollow cylindrical bodies 3 and two identical second hollow cylindrical bodies 4, both made of lithium titanate (LiTaO3) with a relative dielectric constant of 41.4. The intersection of the axes of the four hollow cylindrical bodies in the hollow cylindrical array unit and the surface of the dielectric substrate 2 is at the four corner points of the square. Therefore, the spacing between the two adjacent first hollow cylindrical bodies 3, the spacing between the two adjacent second hollow cylindrical bodies 4, and the spacing between the adjacent first hollow cylindrical body 3 and the second hollow cylindrical body 4 all correspond to the side length L of the square.

[0040] In order to better understand the present application, the performance of the device under different parameters is shown below, where r = 8 μm, r0 = 10 μm, and the remaining parameters are adjusted to show the performance trend.

[0041] Figure 3 As shown in (a) of FIG. 10, when the asymmetric parameter Δr = r1 - r0 increases from 0 μm to 0.8 μm, the symmetry of the structure is destroyed, a resonance peak with gradually increasing line width appears at 3.09 THz, and a red shift gradually appears, which indicates that the symmetrically protected BIC is converted to Q-BIC due to the destruction of the structure, Figure 3 As shown in (a) of FIG. 10, when the asymmetric parameter Δr = r1 - r0 increases from 0 μm to 0.8 μm, the symmetry of the structure is destroyed, a resonance peak with gradually increasing line width appears at 3.09 THz, and a red shift gradually appears, which indicates that the symmetrically protected BIC is converted to Q-BIC due to the destruction of the structure, Figure 3 As shown in (b) of FIG. 10, when the asymmetric parameter Δr = r1 - r0 increases from 0 μm to 0.8 μm, the transmission curve of the unit structure is shown. Figure 4 As shown in (a) of FIG. 10, when the asymmetric parameter Δr = r1 - r0 increases from 0 μm to 0.8 μm, the symmetry of the structure is destroyed, a resonance peak with gradually increasing line width appears at 3.09 THz, and a red shift gradually appears, which indicates that the symmetrically protected BIC is converted to Q-BIC due to the destruction of the structure,Figure 4 (b) in FIG. 1 indicates that when the unit structure asymmetry degree a = (r1-r0) / r1 changes in the range of 0.009~0.08, the Q factor decreases from 20837 to 3010 and meets the quadratic inverse relationship (Q = 20837 / a2) , where the Q factor reaches 20837 at a frequency of 3.126 THz. Figure 4 (c) in FIG. 1 indicates the electric field intensity |E| distribution in the Q-BIC mode formed after the symmetry breaking of the asymmetric parameter a = 0.029.

[0042] Figure 5 (a) in FIG. 1 indicates that in the TD1 mode, the contribution of the ring dipole (T) dominates, and the scattering power of the magnetic dipole (M) and the electric quadrupole (Qe) is significantly suppressed near the resonance frequency. Figure 5 (b) in FIG. 1 indicates that in the Q-BIC mode, the contribution of the ring dipole (T) dominates, and the coupling effect of the ring dipole (T) resonance and the electric dipole (P) can excite the contribution of the magnetic quadrupole (Qm). Figure 6 (a) in FIG. 1 indicates the structure top view magnetic field diagram in the TD1 mode, and the magnetic field energy is mainly localized in the right two hollow cylindrical structures. The closed displacement current (indicated by black arrows) forms a vortex-like distribution around the cylinders. Figure 6 (b) in FIG. 1 indicates the structure side view magnetic field diagram, and the magnetic field vectors between adjacent cylinders circulate clockwise, while the outside circulates counterclockwise. Figure 7 (a) in FIG. 1 indicates the structure top view magnetic field diagram in the Q-BIC mode, and the magnetic field and displacement current are mainly concentrated in the left two hollow cylinders. The displacement current directions of the left two cylinders along the x direction are the same. Figure 7 (b) in FIG. 1 indicates the structure side view magnetic field diagram in the Q-BIC mode, and the magnetic field vector circulation direction is opposite to that in the TD1 mode. The magnetic field vectors between adjacent cylinders circulate counterclockwise, while the outside circulates clockwise. Figure 8 indicates the influence relationship of different size parameters of the asymmetric lithium titanate hollow cylindrical metasurface terahertz biosensor on the terahertz wave transmission curve, wherein Figure 8 (a) in FIG. 1 indicates that when the asymmetric lithium titanate hollow cylindrical metasurface unit period P increases from 57 μm to 60 μm, the Q-BIC resonance peak of the terahertz biosensor shifts by approximately 0.015 THz, Figure 8 (b) in FIG. 1 indicates that when the hollow cylindrical hole spacing L of the asymmetric lithium titanate hollow cylindrical metasurface unit increases from 25 μm to 28 μm, the line width of the Q-BIC resonance mode of the terahertz biosensor decreases, Figure 8 (c) in FIG. 1 indicates that when the dielectric substrate thickness H of the asymmetric lithium titanate hollow cylindrical metasurface changes in the range of 30~33 μm, the resonance frequency and line width of the Q-BIC mode of the terahertz biosensor remain stable. Figure 8(d) in FIG. 4 shows that when the hollow cylinder height h of the asymmetric lithium titanate hollow cylinder metasurface in (d) increases from 9 μm to 12 μm, the Q-BIC resonance of the terahertz biosensor shows a clear red shift from 3.227 THz to 3.048 THz, while the line width remains basically unchanged. Figure 9 (a) in FIG. 4 shows that when the hollow cylinder array unit surface of the asymmetric lithium titanate hollow cylinder metasurface terahertz biosensor in (a) is coated with a thin layer of a to-be-detected substance (refractive index n = 1.5) of different thicknesses, the Q-BIC resonance peak frequency shift changes with the thickness of the to-be-detected substance, and when the thickness of the to-be-detected substance increases in the range of 0-11 μm, the resonance peak frequency shift shows a good linear response. ). Figure 9 (b) in FIG. 4 shows the relationship between the Q-BIC resonance peak frequency shift and the refractive index change, and when the refractive index increases from 1.42 to 1.5, the Q-BIC resonance peak frequency shift reaches 25.7 GHz. Figure 9 (c) in FIG. 4 shows the relationship between the Q-BIC resonance quality factor (FoM) and the refractive index change, and when the refractive index of the to-be-detected substance increases from 1.42 to 1.5, the Q-BIC resonance quality factor increases from 2086 to 2205.

[0043] Therefore, in the embodiment, the above-mentioned asymmetric hollow cylinder metasurface terahertz biosensor can be used to detect the content of each component of a biological sample, and the specific method is as follows: the asymmetric lithium titanate hollow cylinder metasurface terahertz biosensor is assembled in the optical path of a terahertz wave detection system, a terahertz detector detects and records the terahertz wave transmission spectrum of the terahertz biosensor, the frequency spectrum data of the Q-BIC resonance peak without a sample is obtained, then the sample solution is dropped onto the surface of the terahertz biosensor and dried into a film, the terahertz wave spectrum of the terahertz biosensor is recorded, and the frequency spectrum data of the Q-BIC resonance peak with the sample is obtained. Thus, by comparing the frequency spectrum changes of the two terahertz wave transmission spectra, the frequency shift or amplitude change of the two Q-BIC resonance peaks before and after the addition of the sample solution can be obtained, and after data conversion processing by a conversion model, the content of the target component in the detected biological sample can be obtained.

[0044] In principle, the frequency shift or amplitude change of the Q-BIC resonance peak before and after adding the sample can determine the change of the refractive index n of the measured substance, and different contents of the target component in the sample solution have different refractive indexes. Therefore, the frequency shift or amplitude change can reflect the content of the target component in the sample. Before actual detection, different Q-BIC resonance peaks of different contents are obtained by placing sample solutions with different contents (different refractive indexes), and then the frequency shift or amplitude change of the Q-BIC resonance peak of different contents from the initial resonance peak before adding the sample is obtained, so that the conversion model can be fitted. In this embodiment, the conversion model adopts a linear model, the dependent variable of which is the frequency shift or amplitude change, and the independent variable is the volume percentage of the target component.

[0045] Taking the sensing detection of methanol as an example, the frequency shift of the Q-BIC resonance peak before and after adding the sample and the calibrated relationship between the content of methanol in the solution are f(x)=-0.0602x+3.415, wherein x is the volume fraction of methanol in the solution x 100, f(x) is the frequency shift (unit: GHz), and 20% methanol corresponds to x, that is, 20% x 100=20, and the corresponding frequency shift is 2.211 GHz.

[0046] Taking the sensing detection of ethanol as an example, the amplitude change of the Q-BIC resonance peak before and after adding the sample and the calibrated relationship between the content of ethanol in the solution are ΔA=-0.00084x+0.0301, wherein x is the volume fraction of ethanol in the solution x 100, and ΔA is the amplitude change, and 20% ethanol corresponds to x, that is, 20% x 100=20, and the corresponding amplitude change of the transmittance is 0.0133.

[0047] Therefore, the above two calibrated relationships can be used as the conversion model of the methanol and ethanol solution, which is used to convert the frequency shift or amplitude change obtained by actual detection to obtain the content of methanol or ethanol in the detected biological sample. It should be noted that for each target component, a conversion model for the target component can be fitted by using the calibration data alone, and is used for sensing detection of the component.

[0048] The above embodiments are only some preferred implementation schemes of the present application, but not intended to limit the present application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, any technical scheme obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An asymmetric hollow cylindrical metasurface based terahertz biosensor, characterized in that, The super surface unit (1) is obtained by periodic arrangement; Each super surface unit (1) is composed of a dielectric substrate (2) and a hollow cylindrical array unit; the hollow cylindrical array unit is composed of four hollow lithium titanate cylinders vertically arranged on the upper surface of the dielectric substrate (2), including two first hollow cylinders (3) and two second hollow cylinders (4), the inner radius of the cross section of the first hollow cylinder (3) is the same as that of the second hollow cylinder (4), the outer radius of the cross section of the first hollow cylinder (3) is smaller than that of the second hollow cylinder (4), and the four hollow cylinders have the same height, and the asymmetric arrangement is formed by the difference in outer radius to introduce asymmetric disturbance; The intersection of the axis of the four hollow cylinders in the hollow cylindrical array unit and the surface of the dielectric substrate (2) is at the four corner points of the square, the two corner points corresponding to the two first hollow cylinders (3) belong to one side of the square, the two corner points corresponding to the two second hollow cylinders (4) belong to the other side of the square, and the side length of the square is 25-28 μm; The inner radius of the cross section of the first hollow cylinder (3) is 7-9 μm, and the outer radius is 9-10 μm; the inner radius of the cross section of the second hollow cylinder (4) is 7-9 μm, and the outer radius is 10-10.5 μm; The unit period of the super surface unit (1) is 57-60 μm; The height of the four hollow cylinders in the hollow cylindrical array unit is 9-12 μm.

2. The asymmetric hollow-cylinder metasurface-based terahertz biosensor of claim 1, wherein, The inner radius of the cross section of the first hollow cylinder (3) is 8 μm, and the outer radius is 10 μm; the inner radius of the cross section of the second hollow cylinder (4) is 8 μm, and the outer radius is 10.1 μm.

3. The asymmetric hollow-cylinder metasurface-based terahertz biosensor of claim 1, wherein, The side length of the square is 27 μm.

4. The asymmetric hollow-cylinder metasurface-based terahertz biosensor of claim 1, wherein, The material of the dielectric substrate (2) is silicon, quartz or polyimide, and the thickness is 30-33 μm.

5. A method for detecting the content of a component in a biological sample, characterized by, The non-symmetric hollow cylindrical super surface terahertz biosensor according to any one of claims 1-4 is fixed in the optical path of a terahertz wave detection system, the terahertz wave is vertically incident from one side of the hollow cylindrical array unit, the transmission spectrum of the terahertz biosensor is detected and recorded without adding a sample solution, then the biological sample solution to be tested is dropped on the surface of the terahertz biosensor and dried into a film, the transmission spectrum of the terahertz biosensor is detected and recorded, the Q-BIC resonance peaks are extracted from the terahertz wave transmission spectra before and after the sample solution is added, and the frequency shift or amplitude change is calculated, and the content of the target component in the biological sample solution to be tested is obtained through a conversion model fitted in advance for the target component.

6. The method of claim 5, wherein the biological sample is blood. The conversion model adopts a linear model, the dependent variable is the frequency shift or amplitude change, and the independent variable is the volume percentage of the target component.

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