A reflective terahertz metasurface sensor, a biochemical detection system and application

Abstract

The application discloses a reflective terahertz metasurface sensor, a biochemical detection system and application, and the sensor comprises a resonance unit with a preset period length, and the resonance unit comprises, from top to bottom, a first gold layer, a first chromium layer, a polyimide material layer, a second gold layer, a second chromium layer and a silicon dioxide material layer; wherein the width and length of the first gold layer have a preset ratio, the first gold layer and the second gold layer have a first preset thickness, and the polyimide material layer has a second preset thickness, and the application has the advantages of improved detection precision, effective differential detection of trace biochemical samples and the like.

Description

Technical Field

[0001] This application relates to the field of biosensor technology, and in particular to a reflective terahertz metasurface sensor, a biochemical detection system, and its applications. Background Technology

[0002] Biochemical molecules such as amino acids, nucleic acids, and carbohydrates serve as a crucial research foundation for medical, industrial, and environmental science applications. They are diverse, widely distributed, and most are present at extremely low concentrations, ranging from millimoles (mM) to femtomoles (fM). This significantly increases the difficulty of accurately detecting the content of biochemical molecules in organisms. Currently, mainstream biochemical detection methods include chromatography, electrochemical analysis, and spectroscopy. However, these methods are extremely costly, involve complex experimental procedures, and are selective for specific samples, leading to significant limitations. Therefore, finding new detection methods is crucial. Terahertz waves, with frequencies between 0.1 and 10 THz (corresponding wavelengths of approximately 0.03–3 mm), lie in the transition region between microwaves and infrared light in the electromagnetic spectrum, a region previously named the "terahertz gap." In recent years, with technological breakthroughs, the research and application of terahertz waves have rapidly developed, becoming a focus of attention in physics, materials science, communications, and biomedicine.

[0003] Metamaterials, also known as metamorphic materials, are artificial structural materials with unique electromagnetic properties. Compared to natural materials, terahertz metamaterials exhibit some unique electromagnetic characteristics, such as negative refractive index, negative permeability, and negative permittivity. The unit cell size of terahertz metamaterials is smaller than the wavelength of terahertz waves, thus enabling modulation of terahertz waves. Terahertz metasurfaces are a form of two-dimensional metamaterial in the terahertz frequency band. However, existing terahertz metasurface sensors have low detection accuracy, making it difficult to effectively distinguish and detect trace amounts of biochemical samples. Summary of the Invention

[0004] The main purpose of this application is to provide a reflective terahertz metasurface sensor, a biochemical detection system and its application, in order to solve the technical problem that existing terahertz metasurface sensors have low detection accuracy and are difficult to effectively distinguish and detect trace biochemical samples.

[0005] To achieve the above objectives, this application provides a reflective terahertz metasurface sensor, including a resonant unit with a preset period length. The resonant unit includes a first gold layer, a first chromium layer, a polyimide material layer, a second gold layer, a second chromium layer, and a silicon dioxide material layer connected sequentially from top to bottom. The width and length of the first gold layer have a preset ratio, the first gold layer and the second gold layer have a first preset thickness, and the polyimide material layer has a second preset thickness.

[0006] Optionally, the width of the first gold layer is 64 μm, the length of the first gold layer is 322 μm, the first preset thickness is 200 nm, and the second preset thickness is 3 μm.

[0007] Optionally, the thickness of both the first and second chromium layers is 20 nm, and the thickness of the silicon dioxide material layer is 500 μm.

[0008] Optionally, the preset period length is 345μm.

[0009] Optionally, the thickness direction of the resonant unit is the direction of terahertz electromagnetic wave propagation.

[0010] To achieve the above objectives, this application also provides a biochemical detection system, including a λ / 2 waveplate and a beam splitter. After laser light is incident on the λ / 2 waveplate, it is split into transmitted light and reflected light by the beam splitter. A first reflecting mirror, a second reflecting mirror, a third reflecting mirror, a fourth reflecting mirror, a fifth reflecting mirror, a first convex lens, and an InAs crystal are sequentially arranged along the optical path of the transmitted light. The laser light generates a terahertz wave after passing through the InAs crystal. A first off-axis parabolic mirror, a sixth reflecting mirror, a seventh reflecting mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, an eighth reflecting mirror, and a fourth off-axis parabolic mirror are sequentially arranged along the propagation path of the terahertz wave. A reflective terahertz metasurface sensor as described in any one of claims 1-5 is disposed between the second and third off-axis parabolic mirrors. A ninth reflecting mirror, a tenth reflecting mirror, an eleventh reflecting mirror, a second reflecting mirror, a thirteenth reflecting mirror, a fourteenth reflecting mirror, and a fifteenth reflecting mirror are sequentially arranged along the optical path of the reflected light. The system also includes a beam combiner and a ZnTe... The crystal, the second convex lens, the λ / 4 waveplate, the prism, and the photodetector are used to combine the reflected light from the fifteenth reflecting mirror with the terahertz wave reflected from the fourth off-axis parabolic mirror into the ZnTe crystal under the action of the beam combiner, and finally receive it by the photodetector.

[0011] To achieve the above objectives, this application also provides an application of a reflective terahertz metasurface sensor for detecting biochemical solutions.

[0012] Optionally, the biochemical substance solution is an amino acid solution or a protein solution.

[0013] Optionally, the resonance frequency shift Δf of the sensor's resonance peak satisfies the following relationship with the refractive index n of the biochemical substance solution: f = 475n + 5.56.

[0014] Optionally, the biochemical solution has a coverage thickness of at least 90 μm on the sensor.

[0015] The beneficial effects that this application can achieve are as follows: This application includes a resonant unit with a preset period length. The resonant unit comprises, from top to bottom, a first gold layer, a first chromium layer, a polyimide material layer, a second gold layer, a second chromium layer, and a silicon dioxide material layer. The width and length of the first gold layer have a preset ratio, the first and second gold layers have a first preset thickness, and the polyimide material layer has a second preset thickness. Based on the multilayer material sensor structure of this application, a reflective terahertz metasurface sensor with surface lattice resonance effect can be formed. Considering that the setting of key parameters for different material layers will have different effects on sensor performance, the key parameters include the preset ratio of the width and length of the first gold layer, the first preset thickness of the first and second gold layers, and the second preset thickness of the polyimide material layer. Therefore, by reasonably setting the above key parameters, the synergistic effect of each key parameter can maximize the sensor performance, i.e., improve detection accuracy, thus making it suitable for the effective differentiation and detection of trace biochemical samples. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 This is a schematic diagram of the structure of a reflective terahertz metasurface sensor according to an embodiment of this application; Figure 2 for Figure 1 A top view structural diagram; Figure 3 The reflection spectrum of the metasurface sensor in the embodiments of this application corresponds to the initial structure; Figure 4 This is a schematic diagram of the electric field distribution and surface current distribution of the resonant unit at 1.6THz in an embodiment of this application; Figure 5 The reflection spectra of the resonant unit at different terahertz light polarization angles in the embodiments of this application are shown. Figure 6 This is a schematic diagram showing the relationship between the Q value of the resonance peak of the resonance unit and the refractive index sensitivity S and the polarization angle of the incident light in the embodiments of this application. Figure 7 This is a schematic diagram illustrating the influence of different parameters (gold layer thickness, PI thickness, and ratio k) on the sensing performance of the metasurface sensor in the embodiments of this application. Figure 8 The reflection spectrum of the metasurface sensor with optimized structure in the embodiments of this application is shown. Figure 9This is a schematic diagram of the structure of a biochemical detection system according to an embodiment of this application; Figure 10 This is a schematic diagram showing the transmission spectra and the fitting results of the refractive index sensitivity of the metasurface sensor for adding biochemical solutions with different coverage thicknesses in the embodiments of this application. Figure 11 This is a schematic diagram showing the correspondence between the refractive index and sensitivity of the metasurface sensor and the coverage thickness of the biochemical substance solution in the embodiments of this application.

[0018] Figure label: 110 - First gold layer, 120 - First chromium layer, 130 - Polyimide material layer, 140 - Second gold layer, 150 - Second chromium layer, 160 - Silicon dioxide material layer.

[0019] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0022] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0024] Example 1 Reference Figures 1-8 This embodiment provides a reflective terahertz metasurface sensor, including a resonant unit with a preset period length (the period length determines the operating frequency range of the metasurface, thereby designing and analyzing the reflective performance of the terahertz metasurface for biochemical sensing detection). The resonant unit includes a first gold layer 110, a first chromium layer 120, a polyimide material layer 130, a second gold layer 140, a second chromium layer 150, and a silicon dioxide material layer 160 connected sequentially from top to bottom. The width and length of the first gold layer 110 have a preset ratio, the first gold layer 110 and the second gold layer 140 have a first preset thickness, and the polyimide material layer 130 has a second preset thickness.

[0025] The sensing mechanisms of metasurface sensors mainly include dipole resonance, LC resonance, Fano resonance, EIT-like resonance, BIC resonance, and surface lattice resonance. Among these, surface lattice resonance (SLR) occurs in periodically arranged metal nanoarrays. This is caused by the coupling between local surface plasmon resonance and the diffraction modes of the metal array (such as Bragg scattering). This coupling effect can produce a significant local field enhancement. Theoretically, SLR can achieve extremely narrow resonance linewidths. However, this goal faces certain challenges in practical experiments, mainly due to the difficulty in fabricating ultra-precise and defect-free periodic nanoarrays.

[0026] Therefore, in this embodiment, based on the multilayer material sensor structure of this embodiment, a reflective terahertz metasurface sensor with surface lattice resonance effect can be formed. At the same time, considering that the setting of key parameters of different material layers will have different effects on sensor performance, the key parameters include the width and length of the first gold layer 110 at a preset ratio, the first preset thickness of the first gold layer 110 and the second gold layer 140, and the second preset thickness of the polyimide material layer 130. Therefore, by reasonably setting the above key parameters, the synergistic effect of the key parameters can maximize the sensor performance, that is, improve the detection accuracy, so that it can be applied to the effective differentiation and detection of trace biochemical samples.

[0027] It should be noted that the main performance indicators of terahertz sensors are: quality factor Q, sensitivity S, and FOM value. The sensing performance of a terahertz metasurface sensor is determined by its sensitivity S and quality factor Q. Sensitivity S is determined by the sensing volume, which refers to the overlapping area between the field distribution of the resonant mode and the sample being measured. Therefore, enhancing the local field and improving the interaction between the material and the field are key to improving sensitivity S. The quality factor Q depends on the sensor's losses; therefore, reducing the radiation loss of metal sensors is an important means to achieve a high Q value. When the surface of the sensor is covered by the sample, the sample causes changes in the environmental parameters around the sensor, thereby altering the sensor's resonant frequency. A sensor whose resonant frequency changes with the refractive index of the surrounding environment is called a refractive index sensor. Sensing is performed by measuring the frequency shift of the spectral resonance peak. Sensitivity S is usually defined as the frequency shift change Δf multiplied by the change in the refractive index of the sample. The ratio between Δf and Δn is expressed as: S = Δf / Δn. The quality factor Q can be used to characterize the sensor's resolution. The larger the quality factor Q, the narrower the linewidth of the resonance peak and the sharper the resonance peak. It can be defined as the ratio of the center frequency f0 of the resonance peak to the full width at half maximum (FWHM), expressed as: Q = f0 / FWHM. To comprehensively quantify the sensitivity S and the quality factor Q, the FOM value is introduced, expressed as: FOM = S / FWHM. The larger the FOM value, the better the sensor's sensing performance. In summary, the sensor's quality factor Q reflects the sharpness of the resonance peak, the sensitivity S reflects the frequency shift of the resonance peak, and the FOM value can be used to comprehensively consider the sensor's sensing performance. In addition, the resonance peak modulation depth MD is also an important parameter characterizing the terahertz metasurface sensing performance, expressed as: MD = (T max -T min ) / (T max +T min ).

[0028] To obtain the optimal values ​​of the aforementioned key parameters to meet the sensor's high quality factor Q and high sensitivity S requirements, based on the sensing performance and mechanism of the metasurface sensor, the initial sensor structure is initially set as follows: the length Lx of the first gold layer 110 is 322 μm, its width Ly is 184 μm, the first preset thickness of both the first gold layer 110 and the second gold layer 140 is 200 nm, and the second preset thickness of the polyimide material layer 130 (PI layer) is 3 μm. Electromagnetic simulation software is used, employing the finite-difference time-domain method for simulation calculations. The electromagnetic wave propagates along the direction directly opposite the first gold layer 110, and the reflection spectrum of the initial structure is as follows: Figure 3 As shown.

[0029] Depend on Figure 3 It can be seen that when the electric field direction is along the y-direction (TE wave), a significant resonance peak appears at 1.6 THz. To further explore the mechanism of this resonance peak, simulation studies were conducted on the electric field distribution and surface current distribution at 1.6 THz on the sensor. The simulation results are as follows: Figure 4 As shown. Figure 4 (a) shows the electric field distribution of the metasurface metallic structure. Figure 4 (b) The electric field distribution at the interface between the metal structure and the dielectric along the electromagnetic wave propagation direction of the metasurface is given. Figure 4 (c) shows the current distribution diagram of this metasurface. Figure 4 (b) It can be seen that a dipole oscillation mode is formed at the interface between the metal structure and the dielectric. In addition, the Wood's anomaly in the periodic array has a significant impact on this mode, and the resonance wavelength of this resonance peak matches the resonance wavelength of MA(-1, 0). Therefore, the high-Q resonance peak at 1.6 THz is excited by the surface lattice resonance effect.

[0030] Here, a preset ratio is set as k, k = Ly / Lx. The effects of the gold layer thickness (i.e., the first preset thickness), the PI layer thickness (i.e., the second preset thickness), and the structural parameter k on the sensing performance of this metasurface sensor are considered. The research results are as follows: Figure 7 As shown. Figure 7 As shown in (a) and (b), with the increase of gold layer thickness, the resonance peak gradually shifts to lower frequencies, and the Q value gradually decreases. However, the effect of gold layer thickness on the sensing sensitivity S is not significant, and the sensing sensitivity S remains around 600 GHz / RIU. Figure 7 As shown in (c) and (d), with the increase of PI layer thickness, the resonance peak gradually shifts to lower frequencies, and the Q value gradually decreases. When the PI layer thickness reaches 3 μm, the sensor's sensing sensitivity remains around 600 GHz / RIU. Figure 7As shown in (e) and (f), the quality factor Q of the resonance peak gradually decreases with the increase of the scaling factor k, but the effect on the sensing sensitivity S is not significant. Considering all these factors, to obtain a sensor with superior sensing performance, the gold layer thickness can be set to 200 nm, the PI layer thickness to 3 μm, and k≈0.2, i.e., Lx=322 μm and Ly=64 μm. The optimized metasurface sensor reflectance spectrum is as follows: Figure 8 As shown. At this time, the resonance frequency of the resonance peak is 1.604 THz, the quality factor Q=534, and the refractive index sensitivity S=615 GHz / RIU, which can meet the requirements for high-precision detection of trace biochemical samples.

[0031] In addition, when determining the optimal values ​​of the above key parameters, the other parameters are also adjusted accordingly. For example, the thickness of the first chromium layer 120 and the second chromium layer 150 is set to 20nm, the thickness of the silicon dioxide material layer 160 is set to 500μm, and the preset period length is set to 345μm.

[0032] To investigate the effect of the polarization angle of incident terahertz light on the resonance peak characteristics, the sensor reflection spectrum was simulated for polarization angles θ of 0°, 3°, 5°, 10°, and 20°. The simulation results are as follows: Figure 5 and Figure 6 As shown in the figure. The simulation results show that when the terahertz light is incident normally (θ = 0°), the metasurface sensor has the highest sensing sensitivity, reaching 580 GHz / RIU. As the polarization angle increases, the resonance frequency of the resonance peak gradually decreases, the Q value gradually increases, and correspondingly, the sensing sensitivity decreases significantly, dropping to about 350 GHz / RIU. Therefore, the thickness direction of the resonant unit is taken as the propagation direction of the terahertz electromagnetic wave, that is, the propagation direction of the terahertz electromagnetic wave is perpendicular to the incident resonant unit.

[0033] In summary, this embodiment designed a rectangular metal reflective terahertz metasurface sensor based on surface lattice resonance effect, and simulated and analyzed the sensing performance and sensing mechanism of the metasurface under its initial structural parameters. Specifically, the influence of the structural parameters of the metasurface (including the thickness of the gold layer, the thickness of the PI layer, and the aspect ratio k of the rectangular metal) on its sensing performance (including the quality factor Q and the refractive index sensitivity S) was studied and optimized. The optimized metasurface structural parameters are: Lx=322μm, Ly=64μm, structural period length P=345μm, gold layer thickness of 200nm, thickness of the first chromium layer 120 and the second chromium layer 150 of 20nm, PI layer thickness of 3μm, and silicon dioxide material layer 160 thickness of 500μm. The resonance peak frequency of the optimized metasurface is 1.604THz, the quality factor Q=534, and the refractive index sensitivity S=615GHz / RIU, thus meeting the high-precision detection requirements of trace biochemical samples.

[0034] Example 2 Reference Figure 9 This embodiment provides a biochemical detection system, including a λ / 2 waveplate and a beam splitter. Laser light incident on the λ / 2 waveplate is split into transmitted and reflected light by the beam splitter. A first reflecting mirror, a second reflecting mirror, a third reflecting mirror, a fourth reflecting mirror, a fifth reflecting mirror, a first convex lens, and an InAs crystal are sequentially arranged along the optical path of the transmitted light. The laser light generates a terahertz wave after passing through the InAs crystal. A first off-axis parabolic mirror, a sixth reflecting mirror, a seventh reflecting mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, an eighth reflecting mirror, and a fourth off-axis parabolic mirror are sequentially arranged along the propagation path of the terahertz wave. A reflective terahertz metasurface sensor (coated with a biochemical solution) as described in any one of claims 1-5 is disposed between the second and third off-axis parabolic mirrors. A ninth reflecting mirror, a tenth reflecting mirror, an eleventh reflecting mirror, a second reflecting mirror, a thirteenth reflecting mirror, a fourteenth reflecting mirror, and a fifteenth reflecting mirror are sequentially arranged along the optical path of the reflected light. The system also includes a beam combiner and a ZnTe... The crystal, the second convex lens, the λ / 4 waveplate, the prism, and the photodetector are used to combine the reflected light from the fifteenth reflecting mirror with the terahertz wave reflected from the fourth off-axis parabolic mirror into the ZnTe crystal under the action of the beam combiner, and finally receive it by the photodetector.

[0035] Since most terahertz metasurface sensors are currently transmission-type, their detection results are affected by the thickness of the liquid sample when used in conjunction with a transmission-type THz time-domain spectroscopy system for liquid sample detection. Therefore, special sample processing is required, such as using sample containers of specific thicknesses, which increases the complexity of sample handling. To address this, this embodiment designs a biochemical detection system that can effectively work with the sensor in Embodiment 1, achieving excellent sensing performance. Compared to transmission-type detection systems, the light source and detector in this biochemical detection system can be configured on the same side, greatly simplifying the overall design and maintenance of the optical path. Combining the sensor in Embodiment 1 with this biochemical detection system also effectively avoids the sample thickness issue. By analyzing the information reflected back from the sample surface by terahertz light, sample properties such as refractive index, absorptivity, and dielectric constant can be effectively evaluated.

[0036] The working principle of this embodiment is as follows: The femtosecond laser generated by the laser (not shown in the figure) enters the system through a λ / 2 waveplate (HWP) and is split into two beams (transmitted light and reflected light) by a beam splitter (PBS). The transmitted light, with higher power, serves as the pump light. After passing through mirrors M1-M5 and a convex lens L1, it is incident on the InAs crystal to generate a terahertz wave. Subsequently, the terahertz wave is focused onto the probe crystal ZnTe by four off-axis parabolic mirrors PM1-PM4 and three mirrors M6-M8. The metal mirrors M6 and M7 can have their reflectivity increased by plating gold on their surfaces to reduce the loss of the terahertz light during transmission. The reflected light serves as the probe light, and after passing through mirrors PM9-PM15, it coincides with the terahertz wave on the ZnTe crystal under the action of a beam combiner. When the THz electric field acts on the ZnTe crystal, it modulates the polarization state of the probe beam. This modulation effect is directly related to the time-domain waveform of the terahertz electric field. Subsequently, the probe light passes sequentially through convex lens L2 and a λ / 4 waveplate (QWP), where its polarization state is further modulated. It is then separated into two orthogonally polarized beams by a Wollaston prism (BS). These two beams are received by a photodetector, processed by a lock-in amplifier, and finally analyzed by a computer. It should be noted that reflectors M1 and M2 can be placed on an electrically driven translation stage. As the stage moves, terahertz time-domain pulses at different time points can be detected. Continuous acquisition yields the entire terahertz time-domain waveform, which can then be obtained through Fourier transform to obtain the frequency domain spectrum of the terahertz wave.

[0037] Example 3 Reference Figures 10-11 This embodiment provides an application of a reflective terahertz metasurface sensor, which is used to detect biochemical solutions, such as amino acid solutions or protein solutions, and is highly suitable for the high-precision measurement requirements of such biochemical solutions.

[0038] Calculations show that the metasurface sensor has a quality factor Q = 381 and a modulation depth MD = 70% at the resonance peak of 1.6 THz. To calculate the sensitivity of this metasurface sensor, a 50 μm thick layer of the analyte (i.e., a biochemical solution) was added to the surface of the sensor. The refractive index of the analyte was varied, and the transmission spectrum was simulated, as shown below. Figure 10 As shown in (a), the quantitative relationship between the resonance frequency shift of the resonance peak and the refractive index of the measured object is further given, such as Figure 10 As shown in (b), it can be seen that there is a linear relationship between the frequency shift of the intermediate transmission peak and the change in the refractive index of the measured object, and the relationship can be expressed as follows: f = 475n + 5.56, therefore the refractive index sensitivity S = 475 GHz / RIU. Based on this relationship, the detection of biochemical solutions can be effectively guided.

[0039] To investigate the effect of the coating thickness of the measured object on the refractive index sensitivity of the metasurface sensor, simulations were performed to calculate the refractive index sensitivity of the metasurface sensor for coating thicknesses of 5 μm, 10 μm, 15 μm, 30 μm, 60 μm, 80 μm, 100 μm, and 120 μm. The results are as follows: Figure 11 As shown in the figure. The results indicate that the refractive index sensitivity of the metasurface to sample detection gradually increases with the increase of the coating thickness. When the thickness increases to 90 μm, the refractive index sensitivity of the metasurface to sample detection tends to stabilize and remain around 600 GHz / RI. Therefore, the coating thickness of the biochemical solution on the sensor is set to be at least 90 μm.

[0040] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A reflective terahertz metasurface sensor, characterized in that, It includes a resonant unit with a preset period length. The resonant unit includes a first gold layer, a first chromium layer, a polyimide material layer, a second gold layer, a second chromium layer, and a silicon dioxide material layer connected from top to bottom. The width and length of the first gold layer have a preset ratio, the first gold layer and the second gold layer have a first preset thickness, and the polyimide material layer has a second preset thickness.

2. The reflective terahertz metasurface sensor as described in claim 1, characterized in that, The width of the first gold layer is 64 μm, the length of the first gold layer is 322 μm, the first preset thickness is 200 nm, and the second preset thickness is 3 μm.

3. A reflective terahertz metasurface sensor as described in claim 2, characterized in that, The thickness of the first chromium layer and the second chromium layer is 20 nm, and the thickness of the silicon dioxide material layer is 500 μm.

4. A reflective terahertz metasurface sensor as described in claim 1, characterized in that, The preset period length is 345μm.

5. A reflective terahertz metasurface sensor as described in claim 1, characterized in that, The thickness direction of the resonant unit is the direction of terahertz electromagnetic wave propagation.

6. A biochemical detection system, characterized in that, The system includes a λ / 2 waveplate and a beam splitter. After laser light is incident on the λ / 2 waveplate, it is split into transmitted and reflected light by the beam splitter. Along the optical path of the transmitted light, a first reflecting mirror, a second reflecting mirror, a third reflecting mirror, a fourth reflecting mirror, a fifth reflecting mirror, a first convex lens, and an InAs crystal are sequentially arranged. After the laser light passes through the InAs crystal, a terahertz wave is generated. Along the propagation path of the terahertz wave, a first off-axis parabolic mirror, a sixth reflecting mirror, a seventh reflecting mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, an eighth reflecting mirror, and a fourth off-axis parabolic mirror are sequentially arranged. A reflective terahertz metasurface sensor, as described in any one of claims 1-5, is disposed between the second and third off-axis parabolic mirrors. Along the optical path of the reflected light, a ninth reflecting mirror, a tenth reflecting mirror, an eleventh reflecting mirror, a second reflecting mirror, a thirteenth reflecting mirror, a fourteenth reflecting mirror, and a fifteenth reflecting mirror are sequentially arranged. The system also includes a beam combiner and a ZnTe... The crystal, the second convex lens, the λ / 4 waveplate, the prism, and the photodetector are used to combine the reflected light from the fifteenth reflecting mirror with the terahertz wave reflected from the fourth off-axis parabolic mirror into the ZnTe crystal under the action of the beam combiner, and finally receive it by the photodetector.

7. The application of a reflective terahertz metasurface sensor as described in any one of claims 1-5, characterized in that, The sensor is used to detect biochemical solutions.

8. The application of the reflective terahertz metasurface sensor as described in claim 7, characterized in that, The biochemical substance solution is an amino acid solution or a protein solution.

9. The application of the reflective terahertz metasurface sensor as described in claim 7, characterized in that, The resonance frequency shift Δf of the sensor's resonance peak satisfies the following relationship with the refractive index n of the biochemical solution: f = 475n + 5.

56.

10. The application of a reflective terahertz metasurface sensor as described in claim 7, wherein the biochemical substance solution has a coverage thickness of at least 90 μm on the sensor.

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