Cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line

Abstract

The invention discloses a cell wide-spectrum detection method based on a terahertz artificial surface plasmon transmission line, and belongs to the field of cell wide-spectrum detection.The cell wide-spectrum detection method comprises the steps that the structure and size of the terahertz SSPP transmission line are designed, and a detection cavity packaged with the terahertz SSPP transmission line is prepared; connecting the detection chamber with a terahertz test platform, enabling the to-be-detected blood sample to flow into the detection chamber, and starting the test platform; the method comprises the following steps: irradiating an incident terahertz wave beam to the upper surface of a transmission line by using a high-resolution and large-dynamic terahertz frequency domain scanning test technology, efficiently coupling an incident terahertz free space wave with the transmission line, and exciting an SSPP wave with a high local characteristic on the surface of the transmission line; phase, amplitude and cut-off frequency data of an SSPP wave transmission spectrum are obtained, terahertz spectrum characteristics of cells are analyzed, and non-contact, unmarked and high-sensitivity detection and qualitative recognition of cell wide-spectrum information are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of cell broadband detection, and in particular relates to a cell broadband detection method based on terahertz artificial surface plasmon transmission lines. Background Art

[0002] Terahertz waves refer to electromagnetic waves with frequencies between 0.1-10THz. Their wavelength is close to the cellular scale and their radiation energy is low. They have the advantages of being non-invasive and non-ionizing. At the same time, they are particularly sensitive to water, the substance with the most content in living organisms. They are expected to capture the differences in electrical properties of cells based on changes in their water content, and solve the problem of non-contact, high-sensitivity, label-free, precise quantitative identification of cells.

[0003] With the continuous development of terahertz technology, it has shown broad application prospects in the field of biosensing. At present, the main methods of using terahertz waves for biological cell detection can be roughly divided into three types: the first is terahertz metasurface resonance technology, which uses artificial electromagnetic metasurfaces to construct terahertz resonant devices, and then uses the high Q value characteristics of resonant devices to achieve differential detection of biological cells; the second is the free space method, which uses terahertz waves to directly irradiate samples to achieve differential detection of biological cells; the third method is the transmission line method, which uses various types of terahertz waveguides / transmission line devices to achieve the detection of micron-scale cell particles or solutions and other substances. However, among the above three methods, the resonance method and the free space method are both difficult to achieve wide-spectrum detection of single cells, and are currently mostly used for the detection of cell solutions or biological tissue slices. Although the transmission line method has the potential to achieve wide-spectrum detection of single cells, it is still in the simulation exploration stage. It has not yet carried out targeted designs for sensor performance, chamber packaging, test processes, etc. based on the actual conditions such as the inherent characteristics of cells and the performance of the test platform. Since the wide-spectrum detection method takes into account the dispersion characteristics of matter and can perform efficient qualitative cell identification and analysis, there is an urgent need to design a systematic single-cell wide-spectrum detection method based on the transmission line method.

[0004] Terahertz artificial surface plasmon polariton (SSPP) transmission lines have the advantages of convenient feeding, high coupling efficiency, low transmission loss, and high localization, and can achieve efficient transmission of ultra-wideband terahertz signals. Using terahertz SSPP transmission lines to detect single micrometer-scale cells can significantly improve the interaction effect between microcells and terahertz waves, which has important application value in microcell sensing.

[0005] Taking into account factors such as feeding difficulty, coupling efficiency, transmission loss, and micro-nano manufacturing process, the present invention proposes to use terahertz artificial surface plasmon transmission lines as cell sensors, and utilize the high local characteristics of SSPP waves to improve the interaction effect between cell particles and terahertz waves. In combination with commercial high-frequency resolution terahertz scanning test platforms, such as the 364X series network analyzers of Dianco Instruments, the PNA network analyzer of Keysight Technologies, and the collaborative configuration series of VDI spectrum expanders, the single-cell 0.1-2THz wide spectrum high-sensitivity detection can be achieved. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention proposes a cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission lines, which has a reasonable design, solves the shortcomings of the prior art, and has good effects.

[0007] The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line includes the following steps:

[0008] S1. Design the structure and dimensions of the terahertz artificial surface plasmon transmission line. Artificial surface plasmon is referred to as SSPP.

[0009] S2, preparing a detection chamber encapsulated with a terahertz SSPP transmission line;

[0010] S3, connecting the detection chamber to a terahertz test platform, wherein the terahertz test platform includes a vector network analyzer, two spectrum spreading modules, a terahertz transmitting module, a terahertz signal receiving module, and a host computer, wherein the vector network analyzer is connected to the host computer and the two spectrum spreading modules respectively, and the two spectrum spreading modules are connected to the detection chamber through the terahertz transmitting and receiving modules respectively, and the liquid inlet and outlet ports of the detection chamber are connected to a microfluidic chip respectively;

[0011] S4, introducing the blood sample of the patient to be tested into the microfluidic chip connected to the liquid inlet port, and then flowing into the detection chamber after microfluidic enrichment and screening, and then directly starting the terahertz signal scanning test module, or waiting for the background liquid to be emptied before starting;

[0012] S5. The incident terahertz wave is guided to the upper surface of the terahertz SSPP transmission line in the detection chamber through the terahertz signal transmitting module, the incident terahertz wave is efficiently coupled with the transmission line, and a terahertz SSPP wave with a high localized characteristic is excited on the surface of the transmission line;

[0013] S6, the terahertz SSPP wave on the surface of the transmission line in the chamber interacts with the cell particles in the groove channel, so that the amplitude-frequency and phase-frequency characteristics of the transmission coefficient spectrum change, and the SSPP wave containing complete cell information is received by the terahertz signal receiving module;

[0014] S7. By analyzing the terahertz spectral characteristics of the phase, amplitude, and cutoff frequency of the received SSPP wave transmission spectrum data, non-contact, label-free, accurate qualitative identification of cells can be achieved.

[0015] Furthermore, in S1, the structure of the terahertz SSPP transmission line includes a substrate, which is made of low-dielectric, high-light-transmittance materials, including photoresist and polytetrafluoroethylene; a grid unit is provided on the upper surface of the substrate, and the grid unit includes a plurality of grids spaced apart in a one-dimensional periodic array along the length direction of the substrate, and the surface of the grid is coated with a gold film, and the thickness of the gold film is greater than the skin depth of the terahertz wave in the working frequency band.

[0016] Furthermore, the matrix grid includes a flat portion and transition portions at both ends of the flat portion, the grid heights of the flat portion are the same, and the grid heights of the transition portions are designed to be gradually transitioned, and the gradual transition modes include gradient gradual change, sine gradual change and cosine gradual change; the gradient gradual change is designed to have a grid height of i=1,...,m, i represents the i-th grid in the transition part, m is the number of grids in the transition part, and h is the height of the grid in the flush part.

[0017] Furthermore, in S1, the size of the terahertz SSPP transmission line is designed according to the terahertz frequency band to be detected, ensuring that the cutoff frequency of the terahertz SSPP transmission line is within the working frequency band of the terahertz signal transmitting and receiving module, specifically:

[0018] The width g of a single groove between the grids is slightly larger than the cell diameter, ensuring that the grooves can form a microfluidic detection area and allow cell particles to pass through. The number of grooves is designed according to the actual needs of the detection area;

[0019] A preliminary estimate of the transmission line size is given by:

[0020]

[0021] The length direction of the substrate is defined as the x direction, the width direction of the substrate is defined as the y direction, and the height direction of the substrate is defined as the z direction; where k x is the propagation constant of the SSPP wave, k0 is the wave number of the free space wave, h is the height of the flat grid in the z direction, p is the length of the unit node period in the x direction, that is, the sum of the width of a single groove and the thickness of the grid, and g is the width of a single groove in the x direction. h and p are preliminarily estimated by formula (1) to make them in the same order of magnitude, thus suitable for processing;

[0022] Then, by changing the h, p, and g of the transmission line, the dispersion curve is calculated using simulation software, and the cutoff frequency of the transmission line is adjusted to ensure that the cutoff frequency is within the operating frequency band of the terahertz signal transmitting and receiving modules, thereby obtaining the final dimensions of h, p, and g of the transmission line.

[0023] Furthermore, in S2, a detection chamber encapsulated with a terahertz SSPP transmission line is prepared, specifically:

[0024] The detection chamber includes a detection part and a covering part in a rectangular parallelepiped shape. The detection part and the covering part are made of the same material as the substrate. The upper surface of the detection part is used as the substrate. A grid unit structure is etched on the upper surface of the detection part according to the designed size, and then metal plating is performed to form a terahertz SSPP transmission line.

[0025] pouring or depositing packaging materials on the surface of the transmission line grid and inside the groove until the transmission line groove is filled and exceeds the height of the top of the grid unit by about the radius of the cell to be measured;

[0026] The liquid inlet and outlet channels are respectively etched on both sides of the flat grid in the y direction by ultraviolet photolithography. The widths of the liquid inlet and outlet channels are designed according to the actual detection requirements and are both less than or equal to the total length of the flat grid. The height of the liquid inlet channel is approximately equal to the sum of the grid height and the radius of the cell to be tested, and the bottom of the channel is flush with the bottom of the transmission line groove. The height of the liquid outflow channel is approximately equal to the radius of the cell to be tested, and the bottom of the channel is flush with the top of the transmission line grid.

[0027] The packaging material filled with the grid in the center area of ​​the flush part needs to be completely cleaned to form a cell microfluidic channel. The number of grids in the center area of ​​the flush part is designed according to actual needs. The packaging material filled with the grids at both ends of the flush part and the grids in the transition part needs to have the upper surface etched into a smooth plane.

[0028] Finally, the upper surface of the detection part is bonded to the covering part, and the two channels cooperate with the covering part to form a liquid inlet port and a liquid outlet port, thereby obtaining a complete detection chamber.

[0029] Further, in S3, the terahertz signal transmitting and receiving module includes two types, the first type is a terahertz waveguide, including a rectangular waveguide and a microstrip line, and the second type is a terahertz antenna, including various types of horn antennas and photoconductive antennas;

[0030] When excited by the antenna, the antenna radiation beam is directly irradiated onto the upper surface of the terahertz SSPP transmission line, and the beam incident angle is adjusted until the insertion loss is minimum. When excited by the waveguide, the flange is used to connect and position with the detection chamber, specifically:

[0031] On the premise of ensuring that the excitation port is aligned with the terahertz SSPP transmission line, positioning holes of the same size are drilled at corresponding positions on the two sides of the detection chamber without liquid inlet and outlet ports according to the position and specifications of the flange positioning holes.

[0032] Furthermore, in S3, the detection process adopts the chamber inversion detection method or the chamber upright detection method. In the chamber inversion detection method, the cell is allowed to stay on the upper surface of the covering part, and the center of the cell is basically aligned with the top of the grid of the flat part, thereby achieving better matching between the cell and the area with the strongest electric field on the surface of the transmission line; in the chamber upright detection method, the center of the cell is aligned with the top of the transmission line grid, thereby achieving better matching between the cell and the area with the strongest electric field on the surface of the transmission line.

[0033] Beneficial technical effects brought by the present invention:

[0034] The present invention discloses a cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission lines, which solves the current problem of high-sensitivity wide-spectrum detection of single-cell electrical characteristics at the micrometer scale. By designing a high-performance SSPP transmission line with a groove slightly larger than the cell diameter, it is ensured that the cell can pass through the field concentration area; then the packaging chamber is designed, and the SSPP transmission line is packaged inside the chamber, so that the cell is not disturbed by changes in the background environment during the detection process, greatly improving the detection sensitivity; using the high-frequency resolution and large dynamic scanning test platform in the terahertz frequency band, the change law of the transmission line scattering parameters is detected and analyzed, and high-sensitivity detection of wide-spectrum cell characteristic information is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The structure of the terahertz SSPP transmission line designed in the present invention;

[0036] Among them, (a) is the front view of the grid of the transition part; (b) is the front view of the grid of the flush part; (c) is the three-dimensional structure diagram of the transmission line;

[0037] Figure 2 This is the surface etching pattern of the detection part in the present invention;

[0038] Figure 3 It is a perspective view of the detection chamber in the present invention in an upright position;

[0039] Figure 4 It is a detection schematic diagram of the present invention;

[0040] Figure 5 It is a schematic diagram of the connection between the detection chamber and the flange in the present invention;

[0041] Figure 6 This is a flow chart of cell detection in the present invention;

[0042] Figure 7 It is a schematic diagram of the detection system in the present invention; DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is further described below in conjunction with specific embodiments:

[0044] The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line includes the following steps:

[0045] S1. Design the structure and size of the terahertz SSPP transmission line. Artificial surface plasmon is referred to as SSPP.

[0046] The spatial terahertz wave has a very weak response to materials at the cell scale. Considering the high localization characteristics of the SSPP wave, it can amplify the signal changes caused by the material and realize wide-spectrum detection. In order to improve the wide-spectrum detection sensitivity of cells, the terahertz SSPP transmission line is selected as a cell sensor.

[0047] The structure of the terahertz SSPP transmission line includes a substrate, which is made of low-dielectric and high-transmittance materials such as photoresist and polytetrafluoroethylene; a grid unit is provided on the upper surface of the substrate, and the grid unit includes a plurality of grids spaced in a one-dimensional periodic array along the length direction of the substrate. The length direction of the substrate is defined as the x direction, and the cross-sectional shape of the grid along the x direction can be a trapezoid, a rectangle or a triangle. This embodiment takes the trapezoid as an example, and the grid surface is plated with a gold film, and the thickness of the gold film is greater than the skin depth of the terahertz wave in the working frequency band. The processing of the transmission line is compatible with the current traditional semiconductor processing technology, and the surface grid structure can be obtained by ultraviolet lithography or plasmon etching, and the gold film can be prepared by magnetron sputtering.

[0048] The grid unit includes a flat portion and transition portions located at both ends of the flat portion. Figure 1 As shown in (a) and (b), the grid height of the flat part is the same, and the grid height of the transition part is designed to be a gradual transition, so that the phase constant of the SSPP wave on the grid structure gradually changes to a phase constant close to that of the free space wave, thereby improving the coupling efficiency between the incident terahertz wave and the SSPP transmission line. The gradual change methods include gradient gradual change, sine gradual change and cosine gradual change; the gradient gradual change design grid height is i=1,...,m, i represents the i-th grid in the transition part, h is the height of the grid in the flat part, and m is the number of grids in the transition part. m can be reasonably adjusted according to the total number of grid sections of the transmission line.

[0049] According to the terahertz frequency band to be detected, the size of the terahertz SSPP transmission line is designed to ensure that the cutoff frequency of the terahertz SSPP transmission line is within the working frequency band of the terahertz signal transmitting and receiving modules. Specifically:

[0050] The width g of a single groove between the grids is slightly larger than the cell diameter, ensuring that the grooves can form a microfluidic detection area and allow cell particles to pass through. The number of grooves is designed according to the actual needs of the detection area;

[0051] A preliminary estimate of the transmission line size is given by:

[0052]

[0053] The length direction of the substrate is defined as the x direction, the width direction of the substrate is defined as the y direction, and the height direction of the substrate is defined as the z direction; where h is the height of the flat grid in the z direction, p is the length of the unit node period in the x direction, that is, the sum of the width of a single groove and the thickness of the grid, g is the width of a single groove in the x direction, k0 is the wave number of the free space wave, and k x is the propagation constant of the SSPP wave, which indicates the wave number along the propagation direction on the medium interface, i.e., the x direction; h and p are preliminarily estimated by formula (1) so that they are at the same order of magnitude, thus suitable for processing;

[0054] The cutoff frequency of the transmission line is ultimately determined by the size of the transmission line. After a preliminary estimate of the size of the transmission line, an approximate cutoff frequency was selected, and the size of the transmission line was adjusted to achieve the required cutoff frequency. The dispersion curve was calculated using simulation software, and the cutoff frequency of the transmission line was then adjusted to ensure that the cutoff frequency was within the operating frequency band of the terahertz signal transmitting and receiving module, thereby obtaining the final dimensions of h, p, and g of the transmission line. During processing, processing errors can cause changes in the size of the transmission line, which in turn causes changes in the cutoff frequency. Therefore, a certain margin needs to be reserved when setting the cutoff frequency to ensure that the processed SSPP transmission line does not exceed the upper limit of the range of the terahertz signal generating and receiving module.

[0055] The overall structure of the designed terahertz SSPP transmission line is as follows: Figure 1 As shown in (c), the length of the transmission line is L, L = (N + 2i) * p, N is the number of grid nodes in the flat part, and i is the number of grid nodes in the single-side transition part.

[0056] S2. Prepare a detection chamber encapsulated with a terahertz SSPP transmission line, specifically:

[0057] The detection chamber includes a detection part and a covering part in a rectangular parallelepiped shape. The detection part and the covering part are made of the same material as the substrate. The upper surface of the detection part is used as the substrate. A grid unit structure is etched on the upper surface of the detection part according to the designed size, and then metal plating is performed to form a terahertz SSPP transmission line.

[0058] pouring or depositing packaging materials on the surface of the transmission line grid and inside the groove until the transmission line groove is filled and exceeds the height of the top of the grid unit by about the radius of the cell to be measured;

[0059] Ultraviolet photolithography is used to etch liquid inlet and outflow channels on both sides of the flat grid in the y direction. The widths of the liquid inlet and outflow channels are designed according to actual detection requirements and are both less than or equal to the total length of the flat grid. The height h of the liquid inlet channel is approximately equal to the sum of the grid height and the radius of the cell to be tested, and the bottom of the channel is flush with the bottom of the transmission line groove. The height of the liquid outflow channel is approximately equal to the radius of the cell to be tested, and the bottom of the channel is flush with the top of the flat grid. This design can ensure that the cells stay in the detection area on the transmission line and will not be discharged with the liquid, thereby avoiding background solution interference during the detection process and improving detection sensitivity.

[0060] The packaging material filled with the grid in the center area of ​​the flush part needs to be completely cleaned to form a cell microfluidic channel. The number of grids in the center area of ​​the flush part is designed according to actual needs. The packaging material filled with the grids at both ends of the flush part and the grids in the transition part needs to have the upper surface etched into a smooth plane, such as Figure 2 As shown;

[0061] Finally, the upper surface of the detection part is bonded to the cover part to ensure that the liquid cannot flow into the feeding end along the transmission line and cause contamination of the test module. The liquid inlet and outlet channels cooperate with the cover part to form a liquid inlet port and a liquid outflow port, thereby obtaining a complete detection chamber. The detection chamber can be placed upright or inverted when in use. The upright detection chamber is as follows: Figure 3 shown.

[0062] S3, such as Figure 6 and 7 As shown, a test system is built, and the detection chamber is connected to a terahertz test platform. The terahertz test platform includes a vector network analyzer, two spectrum spreading modules, a terahertz transmitting module, a terahertz signal receiving module, and a host computer. The vector network analyzer is connected to the host computer and the two spectrum spreading modules respectively. The two spectrum spreading modules are connected to the detection chamber through the terahertz transmitting and receiving modules respectively. The liquid inlet and outlet ports of the detection chamber are connected to a microfluidic chip respectively.

[0063] There are two types of terahertz signal transmitting and receiving modules. The first type is terahertz waveguide, including rectangular waveguide, microstrip line, etc. The second type is terahertz antenna, including various types of horn antenna, photoconductive antenna, etc.

[0064] When excited by the antenna, the antenna radiation beam is directly irradiated onto the upper surface of the terahertz SSPP transmission line, and the beam incident angle is adjusted until the insertion loss is minimized. When excited by the waveguide, the flange needs to be connected and positioned with the detection chamber, such as Figure 5As shown, under the premise of ensuring that the excitation port is aligned with the terahertz SSPP transmission line, positioning holes of the same size are drilled at corresponding positions on the two sides of the detection chamber that do not have liquid inlet and outlet ports according to the position and specifications of the flange positioning holes, thereby achieving both chamber positioning and improving the coupling efficiency of the terahertz wave and the transmission line to carry out cell detection.

[0065] During the detection process, the chamber inverted detection method or the chamber upright detection method can be used. The chamber inverted detection method allows the cells to stay on the upper surface of the cover part. At this time, the center of the cell is basically aligned with the top of the flat grid, such as Figure 4 As shown, the cell and the area with the strongest electric field on the surface of the transmission line are perfectly matched; in the chamber upright detection method, the center of the cell is aligned with the top of the transmission line grid, thereby achieving a better match between the cell and the area with the strongest electric field on the surface of the transmission line.

[0066] S4, introducing the blood sample of the patient to be tested into the microfluidic chip connected to the liquid inlet port, and then flowing into the detection chamber after microfluidic enrichment and screening, and then directly starting the test platform, or waiting for the background liquid to be emptied before starting;

[0067] S5. The incident terahertz wave beam is guided to the upper surface of the terahertz SSPP transmission line in the detection chamber through the terahertz signal transmitting module, the incident terahertz wave is efficiently coupled with the transmission line, and a terahertz SSPP wave with a high localized characteristic is excited on the surface of the transmission line;

[0068] S6, the terahertz SSPP wave on the surface of the transmission line in the chamber interacts with the cell particles in the groove channel, so that the amplitude-frequency and phase-frequency characteristics of the transmission coefficient spectrum change, and the SSPP wave containing complete cell information is received by the terahertz signal receiving module;

[0069] S7. By analyzing the terahertz spectral characteristics of the phase, amplitude, and cutoff frequency of the received SSPP wave transmission spectrum data, non-contact, label-free, accurate qualitative identification of cells can be achieved.

[0070] The terahertz SSPP transmission line proposed in the present invention is used as a cell sensor, which utilizes the high local characteristics of SSPP waves to improve the interaction effect between cell particles and terahertz waves, and cooperates with commercial high-frequency resolution terahertz scanning test platforms, such as the 364X series network analyzers of Diancos Instruments, the PNA network analyzer of Keysight Technologies and the VDI spectrum expander collaborative configuration series, to achieve high-sensitivity detection of single cells with a wide spectrum of 0.1-2THz. Since the current commercial instruments can only reach 0.1-1.5THz, when test instruments with a frequency band of 1.5-2THz are available in the future, high-sensitivity detection of single cells with a wide spectrum of 1.5-2THz can be achieved.

[0071] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission lines, characterized in that: The following steps are involved: S1. Design the structure and dimensions of the terahertz artificial surface plasmon transmission line. Artificial surface plasmon is referred to as SSPP. S2, preparing a detection chamber encapsulated with a terahertz SSPP transmission line; S3, connecting the detection chamber to a terahertz test platform, wherein the terahertz test platform includes a vector network analyzer, two spectrum spreading modules, a terahertz transmitting module, a terahertz signal receiving module, and a host computer, wherein the vector network analyzer is connected to the host computer and the two spectrum spreading modules respectively, and the two spectrum spreading modules are connected to the detection chamber through the terahertz transmitting and receiving modules respectively, and the liquid inlet and outlet ports of the detection chamber are connected to a microfluidic chip respectively; S4, introducing the blood sample of the patient to be tested into the microfluidic chip connected to the liquid inlet port, and then flowing into the detection chamber after microfluidic enrichment and screening, and then directly starting the test platform, or waiting for the background liquid to be emptied before starting; S5. The incident terahertz wave is guided to the upper surface of the terahertz SSPP transmission line in the detection chamber through the terahertz signal transmitting module, the incident terahertz wave is efficiently coupled with the transmission line, and a terahertz SSPP wave with a high localized characteristic is excited on the surface of the transmission line; S6, the terahertz SSPP wave on the surface of the transmission line in the chamber interacts with the cell particles in the groove channel, so that the amplitude-frequency and phase-frequency characteristics of the transmission coefficient spectrum change, and the SSPP wave containing complete cell information is received by the terahertz signal receiving module; S7. By analyzing the terahertz spectral characteristics of the phase, amplitude, and cutoff frequency of the received SSPP wave transmission spectrum data, non-contact, label-free, accurate qualitative identification of cells can be achieved.

2. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 1 is characterized in that: In S1, the structure of the terahertz SSPP transmission line includes a substrate, which is made of low-dielectric, high-light-transmittance materials, including photoresist and polytetrafluoroethylene; a grid unit is provided on the upper surface of the substrate, and the grid unit includes a plurality of grids spaced apart in a one-dimensional periodic array along the length direction of the substrate, and the surface of the grid is plated with a gold film, and the thickness of the gold film is greater than the skin depth of the terahertz wave in the working frequency band.

3. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 2 is characterized in that: The grid unit includes a flat portion and transition portions at both ends of the flat portion. The grid heights of the flat portions are the same. The grid heights of the transition portions are designed to be gradually transitioned. The gradual transition modes include gradient gradual change, sine gradual change and cosine gradual change. The gradient gradual change is designed to have a grid height of i represents the i-th grid in the transition part, m is the number of grids in the transition part, and h is the height of the grid in the flush part.

4. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 3 is characterized in that: In S1, the size of the terahertz SSPP transmission line is designed according to the terahertz frequency band to be detected, ensuring that the cutoff frequency of the terahertz SSPP transmission line is within the working frequency band of the terahertz signal transmitting and receiving module, specifically: The width g of a single groove between the grids is slightly larger than the cell diameter, ensuring that the grooves can form a microfluidic detection area and allow cell particles to pass through. The number of grooves is designed according to the actual needs of the detection area; A preliminary estimate of the transmission line size is given by: The length direction of the substrate is defined as the x direction, the width direction of the substrate is defined as the y direction, and the height direction of the substrate is defined as the z direction; where k x is the propagation constant of the SSPP wave, k0 is the wave number of the free space wave, h is the height of the flat grid in the z direction, p is the length of the unit node period in the x direction, that is, the sum of the width of a single groove and the thickness of the grid, and g is the width of a single groove in the x direction. h and p are preliminarily estimated by formula (1) to make them in the same order of magnitude, thus suitable for processing; Then, by changing the h, p, and g of the transmission line, the dispersion curve is calculated using simulation software, and the cutoff frequency of the transmission line is adjusted to ensure that the cutoff frequency is within the operating frequency band of the terahertz signal transmitting and receiving modules, thereby obtaining the final dimensions of h, p, and g of the transmission line.

5. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 4 is characterized in that: In S2, a detection chamber encapsulating a terahertz SSPP transmission line is prepared, specifically: The detection chamber includes a detection part and a covering part in a rectangular parallelepiped shape. The detection part and the covering part are made of the same material as the substrate. The upper surface of the detection part is used as the substrate. A grid unit structure is etched on the upper surface of the detection part according to the designed size, and then metal plating is performed to form a terahertz SSPP transmission line. Pour or deposit packaging materials on the surface of the transmission line grid and inside the groove until the transmission line groove is filled and exceeds the height of the top of the grid by about the radius of the cell to be measured; The liquid inlet and outlet channels are respectively etched on both sides of the flat grid in the y direction by ultraviolet photolithography. The widths of the liquid inlet and outlet channels are designed according to the actual detection requirements and are both less than or equal to the total length of the flat grid. The height of the liquid inlet channel is approximately equal to the sum of the grid height and the radius of the cell to be tested, and the bottom of the channel is flush with the bottom of the transmission line groove. The height of the liquid outflow channel is approximately equal to the radius of the cell to be tested, and the bottom of the channel is flush with the top of the transmission line grid. The packaging material filled with the grid in the center area of ​​the flush part needs to be completely cleaned to form a cell microfluidic channel. The number of grids in the center area of ​​the flush part is designed according to actual needs. The packaging material filled with the grids at both ends of the flush part and the grids in the transition part needs to have the upper surface etched into a smooth plane. Finally, the upper surface of the detection part is bonded to the covering part, and the two channels cooperate with the covering part to form a liquid inlet port and a liquid outlet port, thereby obtaining a complete detection chamber.

6. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 5 is characterized in that: In S3, the terahertz signal transmitting and receiving module includes two types, the first type is a terahertz waveguide, including a rectangular waveguide and a microstrip line, and the second type is a terahertz antenna, including various types of horn antennas and photoconductive antennas; When excited by the antenna, the antenna radiation beam is directly irradiated onto the upper surface of the terahertz SSPP transmission line, and the beam incident angle is adjusted until the insertion loss is minimum. When excited by the waveguide, the flange is used to connect and position with the detection chamber, specifically: Under the premise of ensuring that the excitation port is aligned with the terahertz SSPP transmission line, positioning holes of the same size are drilled at corresponding positions on the two sides of the detection chamber without liquid inlet and outlet ports according to the position and specifications of the flange positioning holes.

7. The cell wide-spectrum detection method based on terahertz artificial surface plasmon transmission line according to claim 5, characterized in that: In S3, the chamber inversion detection method or the chamber upright detection method is used during the detection process. In the chamber inversion detection method, the cell is allowed to stay on the upper surface of the covering part, and the center of the cell is basically aligned with the top of the grid of the flat part, thereby achieving better matching between the cell and the area with the strongest electric field on the surface of the transmission line; in the chamber upright detection method, the center of the cell is aligned with the top of the grid of the transmission line, thereby achieving better matching between the cell and the area with the strongest electric field on the surface of the transmission line.

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