A functionally multiplexed terahertz sensing system and measurement method

Abstract

This invention proposes a functionally multiplexed terahertz sensing system and measurement method, comprising a terahertz transmitter, a split-type bilayer metasurface sensor, a terahertz detector, and a post-processing system. The terahertz transmitter and detector are respectively positioned above and below the sensor for transmitting and receiving terahertz signals. The terahertz detector is connected to the post-processing system for real-time processing and display of the received terahertz signals. The measurement method of this system involves detecting the terahertz signal without a sample, and detecting the terahertz signal of the split-type bilayer metasurface sensor with and without a sample. The post-processing system analyzes two different operating peaks excited by the split-type bilayer metasurface sensor, where the low-frequency broadband dipole resonance peak is used for qualitative molecular fingerprint identification, and the high-frequency narrowband q-BIC resonance peak is used for quantitative refractive index sensing. This invention enables dual-modal functional multiplexing in a single structure and possesses high sensing sensitivity.

Description

Technical Field

[0001] This invention belongs to the field of terahertz sensing technology, specifically relating to a functional multiplexed terahertz sensing system and measurement method. Background Technology

[0002] Terahertz (THz) waves possess characteristics such as non-ionization and low photon energy, and can cover the rotational and vibrational energy levels of a wide range of biochemical molecules, thus showing broad application prospects in molecular fingerprinting and biochemical sensing. However, because terahertz wavelengths are much larger than the molecular scale, trace analytes exhibit weak spectral responses in this band. Traditional terahertz spectroscopy detection often requires large sample volumes or complex sample preparation processes, making it difficult to meet the needs of rapid, trace-level detection.

[0003] To enhance the interaction between terahertz waves and analytes, metasurface-based terahertz sensors have been extensively studied. These sensors can improve sensing sensitivity by enhancing the local electric field through subwavelength structural resonance. Existing technologies have implemented dual-function detection of molecular fingerprinting and refractive index sensing through pixelated metasurface modules and their sub-modules. For example, Chinese patent document CN118883508A discloses a terahertz sensing metasurface device based on quasi-continuous domain bound states. This device obtains a broad-spectrum resonant band for molecular fingerprinting by constructing pixelated metasurface modules and performs refractive index sensing by selecting sub-modules of the pixelated metasurface modules.

[0004] However, the dual-function implementation of the above-mentioned technical solutions mainly relies on the division and selection of pixelated metasurface modules and their sub-modules. Different functions are based on the structural configuration of different modules or sub-modules. Therefore, it is difficult to directly achieve the functional reuse of molecular fingerprint recognition and refractive index sensing in the same sensing structure through different resonance modes. At the same time, further optimization is still needed in terms of reducing the influence of the substrate and improving the spatial overlap between the analyte and the local electric field.

[0005] Therefore, how to excite different operating peaks using the same device without relying on pixelation modules and their sub-modules, and use them for qualitative identification of molecular fingerprints and quantitative sensing of refractive index respectively, while reducing the substrate effect and enhancing the interaction between the analyte and the local electric field, remains a technical problem that urgently needs to be solved in the field of terahertz trace molecular sensing. Summary of the Invention

[0006] The purpose of this invention is to propose a functionally multiplexed terahertz sensing system and measurement method. The sensing system developed in this invention utilizes a split double-layer structure to reduce the adverse effects of the substrate on the near-field energy distribution, and excites two different operating peaks in the same sensor. The low-frequency broadband dipole resonance peak is used for qualitative identification of molecular fingerprints, and the high-frequency narrowband q-BIC resonance peak is used for quantitative refractive index sensing, thereby achieving functional multiplexing in a single device.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A functionally multiplexed terahertz sensing system includes a terahertz transmitter, a split-type bilayer metasurface sensor, a terahertz detector, and a post-processing system. The split-type bilayer metasurface sensor can excite two different operating peaks in the same sensing structure, wherein a low-frequency broadband dipole resonance peak is used for qualitative identification of molecular fingerprints, and a high-frequency narrowband q-BIC resonance peak is used for quantitative refractive index sensing. The terahertz transmitter and terahertz detector are respectively located above and below the split-type bilayer metasurface sensor for transmitting and receiving terahertz signals. The terahertz detector is connected to the post-processing system to process and display the received terahertz signals in real time.

[0009] Preferably, the split dual-layer metasurface sensor includes a substrate, a dielectric support layer formed by a dielectric support structure regularly arranged on the upper surface of the substrate, a top resonator array disposed on the upper surface of the dielectric support layer, and a bottom complementary array disposed on the upper surface of the substrate and located in the gaps of the dielectric support structure; the top resonator array is composed of square resonator units with lateral openings arranged periodically, and the planar pattern of the dielectric support structure is consistent with the planar pattern of the square resonator units.

[0010] Preferably, both the top resonator array and the bottom complementary array are gold layers.

[0011] Preferably, the array period of the square resonant unit along the two orthogonal directions is 120μm; the outer side length of the square resonant unit is 90μm, and the lateral opening width is 16μm; the thickness of the dielectric support layer is 15μm.

[0012] Preferably, the split-type bilayer metasurface sensor, serving as a carrier for loading the sample to be tested and exciting two different working peaks, is fabricated using ultraviolet lithography and electron beam evaporation deposition processes: First, an SU-8 photoresist support structure is prepared on a polymethylpentene substrate using ultraviolet lithography, completing the preparation of the substrate and dielectric support layer; then, an electron beam evaporation deposition process is used to prepare a top-layer resonator array and a bottom-layer complementary array on the SU-8 photoresist support structure and the substrate, ultimately forming the split-type bilayer metasurface sensor.

[0013] A measurement method for a functionally multiplexed terahertz sensing system, employing any one of the aforementioned functionally multiplexed terahertz sensing systems, includes the following steps:

[0014] Step S1: There is no separate double-layer metasurface sensor between the terahertz transmitter and the detector. At this time, the terahertz signal obtained by the detection optical path is the reference signal r.

[0015] Step S2: Fix the separate double-layer metasurface sensor without a sample between the terahertz emitter and the detector. At this time, the terahertz signal obtained by the detection optical path is the sample signal s1.

[0016] Step S3: Using a split double-layer metasurface sensor as a carrier, the sample to be tested is loaded onto the sensor surface. At this time, the terahertz signal obtained by the detection optical path is the sample signal s2.

[0017] Step S4: In the post-processing system, using the obtained reference signal r, sample signal s1 and sample signal s2, extract two different working peaks of the split double-layer metasurface sensor, calculate the refractive index sensing sensitivity based on the high-frequency narrowband q-BIC resonance peak, and obtain the molecular fingerprint recognition result based on the low-frequency broadband dipole resonance peak.

[0018] Preferably, step S4, which calculates the refractive index sensing sensitivity of the sensor and the molecular fingerprint recognition characterization quantity, specifically involves:

[0019] Step S41: Convert the detected reference signal r, sample signal s1 and sample signal s2 into terahertz frequency domain amplitude spectra through Fast Fourier Transform (FFT);

[0020] Step S42: Calculate the transmittance spectra of sample signals s1 and s2 using the transmittance spectrum calculation formula. Extract the frequencies corresponding to the resonance peaks of the two transmittance spectra within the high-frequency narrowband q-BIC resonance peak band, and use these frequencies as the resonant frequencies of sample signals s1 and s2. and ;

[0021] Step S43: Based on the frequency shift of the high-frequency narrowband q-BIC resonance peak and combined with the sensitivity calculation formula, the refractive index sensing sensitivity of the sensor is calculated to achieve quantitative analysis of the sample.

[0022] Step S44: Within the molecular fingerprint recognition frequency band corresponding to the low-frequency broadband dipole resonance peak, calculate the difference ΔT in the transmittance spectrum amplitude obtained from sample signals s1 and s2 as a characterization quantity for molecular fingerprint recognition, and determine the type of sample to be tested based on the characteristic peak frequency in the ΔT frequency response, thereby completing the qualitative identification of molecular fingerprint.

[0023] Preferably, the formula for calculating the transmittance spectrum in step S42 is:

[0024]

[0025] in, The terahertz frequency domain amplitude spectrum of sample signal s1 or sample signal s2. The transmittance spectrum is for sample signal s1 or sample signal s2. Let r be the terahertz frequency domain amplitude spectrum of the reference signal r.

[0026] Preferably, the sensitivity calculation formula in step S43 is:

[0027]

[0028] in, and These are the resonant frequencies of sample signals s1 and s2 in the frequency band corresponding to the high-frequency narrowband q-BIC resonance peak, respectively.

[0029] Preferably, the formula for calculating the transmittance spectrum amplitude difference ΔT in step S44 is:

[0030]

[0031] in, and These are the transmittance spectra in the frequency band corresponding to the low-frequency broadband dipole resonance peak, calculated from sample signal s1 and sample signal s2, respectively.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention uses a split double-layer metasurface sensor. The split design reduces the substrate effect and enhances the spatial overlap and interaction strength between the analyte and the local electric field, thereby improving the sensing performance.

[0034] (2) The present invention achieves dual-modal functional reuse in a single device: based on the structural design of the split double-layer metasurface sensor, while retaining the original low-frequency broadband dipole resonance peak of the structure, the in-plane symmetry is broken by introducing a lateral opening configuration in its planar structure, which excites the high-frequency narrowband q-BIC resonance peak, thereby forming two different working peaks in the same sensing structure; among them, the low-frequency broadband dipole resonance peak is used for qualitative identification of molecular fingerprints, and the high-frequency narrowband q-BIC resonance peak is used for quantitative sensing of refractive index. Dual-function detection can be achieved without relying on the division and selection of multiple pixelation modules and their sub-modules. Therefore, the function implementation path is more direct, which is conducive to improving the integration of the sensing structure and simplifying the detection process.

[0035] (3) The preparation process of the present invention is simple and feasible. A support structure can be formed by photolithography and a separate double-layer structure can be prepared by electron beam evaporation coating. The whole process does not require a complicated stripping process, is highly operable, and is easy to process. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the system structure of a preferred embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the cell structure of the split double-layer metasurface sensor in a preferred embodiment of the present invention;

[0038] Figure 3 This is a fitting diagram of the refractive index sensing sensitivity of a preferred embodiment of the present invention;

[0039] Figure 4 This is a comparison of transmittance spectra under different lactose coating thicknesses in a preferred embodiment of the present invention;

[0040] In the figure: 1-Terahertz emitter; 2-Incident terahertz pulse; 3-Lactose molecule; 4-Transmitted terahertz pulse; 5-Terahertz detector; 6-Gold layer; 7-SU-8 photoresist dielectric support layer; 8-TPX substrate; 9-Post-processing system. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1-4 The present invention will be further described in detail with reference to specific embodiments.

[0042] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0043] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] like Figure 1 As shown, this embodiment provides a functionally multiplexed terahertz sensing system, including a terahertz transmitter 1, a split double-layer metasurface sensor, a terahertz detector 5, and a post-processing system 9. The terahertz transmitter 1 and the terahertz detector 5 are respectively located above and below the split double-layer metasurface sensor for transmitting and receiving terahertz signals. The terahertz detector 5 is connected to the post-processing system 9 to process and display the received terahertz signals in real time.

[0045] like Figure 2As shown, in this embodiment, the split-layer metasurface sensor includes a substrate 8, a dielectric support layer 7 formed by a regular arrangement of dielectric support structures on the upper surface of the substrate, a top resonator array disposed on the upper surface of the dielectric support layer 7, and a bottom complementary array disposed on the upper surface of the substrate 8 and located in the gaps of the dielectric support structures. Both the top resonator array and the bottom complementary array are gold layers 6. The split-layer metasurface sensor is a periodic array structure with an array period of 120 μm. The top resonator array is composed of periodically arranged square resonator units with lateral openings. The outer side length of the square resonator unit is 90 μm, and the width of the lateral opening is 16 μm. The dielectric support layer 7 has a thickness of 15 μm, and the planar pattern of the dielectric support structure in the dielectric support layer 7 is consistent with the planar pattern of the square resonator units.

[0046] In this embodiment, the split-type dual-layer metasurface sensor serves as a carrier for loading the sample to be tested and exciting dual-mode surface plasmon resonance. It is fabricated using ultraviolet lithography and electron beam evaporation deposition processes. First, an SU-8 photoresist support structure (dielectric support layer 7) is prepared on a TPX substrate (substrate 8) using ultraviolet lithography, completing the fabrication of the substrate and the dielectric support layer. Subsequently, an electron beam evaporation deposition process is used to prepare a top-layer resonator array and a bottom-layer complementary array on the SU-8 photoresist support structure and the substrate, ultimately forming the split-type dual-layer metasurface sensor.

[0047] When performing the sensing and detection of the sample to be tested, a split-type double-layer metasurface sensor is used as a carrier in the constructed terahertz transmission time-domain spectroscopy detection optical path. This sensor is fixed between the terahertz emitter 1 and the terahertz detector 5. The terahertz emitter 1 and detector 5 are then activated. The incident terahertz pulse 2 emitted by the terahertz emitter 1 passes through the split-type double-layer metasurface sensor via transmission and interacts with it. The terahertz detector 5 receives the transmitted terahertz pulse 4 and transmits the detection signal to the post-processing system 9 for processing, obtaining the sample signal s1. Then, the sample to be tested, lactose molecules 3, is loaded onto the split-type double-layer metasurface sensor, and the above measurement process is repeated to obtain the sample signal s2. The refractive index sensing sensitivity and molecular fingerprint recognition results are obtained based on the processing results of s1 and s2. In this embodiment, the molecular fingerprint recognition process is illustrated using the lactose molecule 3 as an example. Its dielectric response in the terahertz band is characterized by the Drude-Lorentz dielectric model, and its characteristic absorption peak is located at 0.53 THz. Therefore, when a characteristic absorption peak appears in the ΔT frequency response near 0.53 THz, the sample to be tested can be identified as lactose, thus achieving qualitative identification of the molecular fingerprint of lactose.

[0048] The measurement method of this system specifically includes the following steps:

[0049] Step S1: There is no separate double-layer metasurface sensor between the terahertz transmitter and the terahertz detector. At this time, the terahertz signal obtained by the detection optical path is the reference signal r.

[0050] Step S2: Fix the separate double-layer metasurface sensor without a sample between the terahertz emitter and the detector. At this time, the terahertz signal obtained by the detection optical path is the sample signal s1.

[0051] Step S3: Using a split double-layer metasurface sensor as a carrier, the sample to be tested is loaded onto the sensor surface. At this time, the terahertz signal obtained by the detection optical path is the sample signal s2.

[0052] Step S4: In the post-processing system, using the obtained reference signal r, sample signal s1 and sample signal s2, extract two different working peaks of the split double-layer metasurface sensor, calculate the refractive index sensing sensitivity based on the high-frequency narrowband q-BIC resonance peak, and obtain the molecular fingerprint recognition result based on the low-frequency broadband dipole resonance peak.

[0053] Specifically, the calculation of the refractive index sensing sensitivity and molecular fingerprint characterization parameters of the split double-layer metasurface sensor is as follows:

[0054] Step S41: Convert the detected reference signal r, sample signal s1 and sample signal s2 into terahertz frequency domain amplitude spectra through Fast Fourier Transform (FFT);

[0055] Step S42: Calculate the transmittance spectra of sample signals s1 and s2 using the transmittance spectrum calculation formula. Extract the frequencies corresponding to the resonance peaks of the two transmittance spectra within the high-frequency narrowband q-BIC resonance peak band, and use these frequencies as the resonant frequencies of sample signals s1 and s2. and ;

[0056] The formula for calculating the transmittance spectrum is as follows:

[0057]

[0058] in, The terahertz frequency domain amplitude spectrum of sample signal s1 or sample signal s2. The transmittance spectrum is for sample signal s1 or sample signal s2. Let r be the terahertz frequency domain amplitude spectrum of the reference signal r.

[0059] Step S43: Based on the frequency shift of the high-frequency narrowband q-BIC resonance peak and combined with the sensitivity calculation formula, the refractive index sensing sensitivity of the sensor is calculated to achieve quantitative analysis of the sample.

[0060] Among them, sensitivity The calculation formula is:

[0061]

[0062] in, and These are the resonant frequencies of sample signals s1 and s2 within the frequency band corresponding to the high-frequency narrowband q-BIC resonance peak, respectively. denoted as the refractive index of the sample to be tested.

[0063] Step S44: Within the molecular fingerprint recognition frequency band corresponding to the low-frequency broadband dipole resonance peak, calculate the difference ΔT in the transmittance spectrum amplitude obtained from sample signals s1 and s2 as a characterization quantity for molecular fingerprint recognition, and determine the type of sample to be tested based on the characteristic peak frequency in the ΔT frequency response, thereby completing the qualitative identification of molecular fingerprint.

[0064] The formula for calculating the transmittance spectrum amplitude difference ΔT is as follows:

[0065]

[0066] in, and These are the transmittance spectra in the frequency band corresponding to the low-frequency broadband dipole resonance peak, calculated from sample signal s1 and sample signal s2, respectively.

[0067] Performance evaluation of a function-multiplexed terahertz sensing system:

[0068] The performance evaluation of the functional multiplexing terahertz sensing system based on a split double-layer metasurface involves loading samples with different refractive indices or thicknesses onto the surface of the split double-layer metasurface sensor, and then fixing them at a designated position for sensing and detection.

[0069] When samples with different refractive indices are loaded, the transmittance spectrum is calculated from the terahertz frequency domain amplitude spectrum of the samples with different refractive indices. Sensing characterization is then performed based on the change in the resonant frequency shift Δf of the high-frequency narrowband resonance with the change in the refractive index Δn of the sample. The performance of the terahertz sensing system is represented by the sensing sensitivity S. ,in , .

[0070] The refractive index sensing performance of the functionally multiplexed terahertz sensing system was evaluated, and the performance test results of the embodiments of the present invention are as follows: Figure 3 As shown. From Figure 3As can be seen, the resonance peak frequency shift gradually increases with the increase of the refractive index of the sample under test, and the two are linearly correlated, indicating that the split double-layer metasurface sensor has high sensitivity to changes in the surrounding dielectric environment. According to the sensing sensitivity calculation formula of this embodiment, the refractive index sensing sensitivity is S = 0.541 THz / RIU, which has good application capability in quantitative detection of refractive index.

[0071] When samples of different thicknesses are loaded, the transmittance spectrum is calculated from the terahertz frequency domain amplitude spectrum of the samples of different thicknesses. Molecular fingerprinting is then performed based on the attenuation of low-frequency broadband resonances in the molecular characteristic absorption band. The characterization metric for molecular fingerprinting is represented by the transmittance spectrum amplitude difference ΔT. .

[0072] The performance of the molecular fingerprint recognition system of the functionally multiplexed terahertz sensing system was evaluated, and the performance test results of the embodiments of the present invention are as follows: Figure 4 As shown. From Figure 4 It can be seen that as the thickness of the lactose molecules coated on the sensor surface increases, the low-frequency broadband resonance exhibits a significant attenuation characteristic at 0.53 THz. 0.53 THz corresponds to the characteristic absorption peak frequency of lactose molecules, which allows for qualitative identification of the molecular fingerprint of lactose. Simultaneously, the high-frequency narrowband resonance shows a significant redshift, which gradually increases with increasing thickness. When the lactose coating thickness is 10 μm, the redshift reaches 356 GHz, which can be used for quantitative characterization of changes in the equivalent dielectric environment caused by the sample. The split-layer bilayer metasurface sensing system of this invention can simultaneously achieve qualitative identification and quantitative analysis of biomolecules, thus realizing functional reuse. Therefore, the functionally reused terahertz sensing system of this invention has excellent application prospects.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A functionally multiplexed terahertz sensing system, characterized in that: The system includes a terahertz transmitter, a split-layer metasurface sensor, a terahertz detector, and a post-processing system. The split-layer metasurface sensor can excite two different operating peaks in the same sensing structure, whereby the low-frequency broadband dipole resonance peak is used for qualitative identification of molecular fingerprints, and the high-frequency narrowband q-BIC resonance peak is used for quantitative refractive index sensing. The terahertz transmitter and terahertz detector are respectively located above and below the split-layer metasurface sensor for transmitting and receiving terahertz signals. The terahertz detector is connected to the post-processing system to process and display the received terahertz signals in real time.

2. The functional multiplexing terahertz sensing system according to claim 1, characterized in that: The split-type dual-layer metasurface sensor includes a substrate, a dielectric support layer formed by a regular arrangement of dielectric support structures on the upper surface of the substrate, a top resonator array disposed on the upper surface of the dielectric support layer, and a bottom complementary array disposed on the upper surface of the substrate and located in the gaps of the dielectric support structures; the top resonator array is composed of square resonator units with lateral openings arranged periodically, and the planar pattern of the dielectric support structure is consistent with the planar pattern of the square resonator units.

3. The functional multiplexing terahertz sensing system according to claim 2, characterized in that: Both the top resonator array and the bottom complementary array are gold layers.

4. The functional multiplexing terahertz sensing system according to claim 2, characterized in that: The array period of the square resonant unit along the two orthogonal directions is 120μm; the outer side length of the square resonant unit is 90μm, and the lateral opening width is 16μm; the thickness of the dielectric support layer is 15μm.

5. The functionally multiplexed terahertz sensing system according to claim 2, characterized in that: The split-type bilayer metasurface sensor, serving as a carrier for loading the sample to be tested and exciting two different working peaks, is fabricated using ultraviolet lithography and electron beam evaporation deposition processes: First, an SU-8 photoresist support structure is prepared on a polymethylpentene substrate using ultraviolet lithography, completing the preparation of the substrate and dielectric support layer; then, an electron beam evaporation deposition process is used to prepare a top-layer resonator array and a bottom-layer complementary array on the SU-8 photoresist support structure and the substrate, ultimately forming the split-type bilayer metasurface sensor.

6. A measurement method for a functionally multiplexed terahertz sensing system, characterized in that, The terahertz sensing system employing any one of claims 1 to 5 comprises the following steps: Step S1: There is no separate double-layer metasurface sensor between the terahertz transmitter and the detector. At this time, the terahertz signal obtained by the detection optical path is the reference signal r. Step S2: Fix the separate double-layer metasurface sensor without a sample between the terahertz emitter and the detector. At this time, the terahertz signal obtained by the detection optical path is the sample signal s1. Step S3: Using a split double-layer metasurface sensor as a carrier, the sample to be tested is loaded onto the sensor surface. At this time, the terahertz signal obtained by the detection optical path is the sample signal s2. Step S4: In the post-processing system, using the obtained reference signal r, sample signal s1 and sample signal s2, extract two different working peaks of the split double-layer metasurface sensor, calculate the refractive index sensing sensitivity based on the high-frequency narrowband q-BIC resonance peak, and obtain the molecular fingerprint recognition result based on the low-frequency broadband dipole resonance peak.

7. The measurement method for a functionally multiplexed terahertz sensing system based on a split double-layer metasurface according to claim 6, characterized in that: The calculation of the refractive index sensing sensitivity and molecular fingerprint recognition characterization of the sensor in step S4 is as follows: Step S41: Convert the detected reference signal r, sample signal s1 and sample signal s2 into terahertz frequency domain amplitude spectra through fast Fourier transform. Step S42: Calculate the transmittance spectra of sample signals s1 and s2 using the transmittance spectrum calculation formula. Extract the frequencies corresponding to the resonance peaks of the two transmittance spectra within the high-frequency narrowband q-BIC resonance peak band, and use these frequencies as the resonant frequencies of sample signals s1 and s2. and ; Step S43: Based on the frequency shift of the high-frequency narrowband q-BIC resonance peak and combined with the sensitivity calculation formula, the refractive index sensing sensitivity of the sensor is calculated to achieve quantitative analysis of the sample. Step S44: Within the molecular fingerprint recognition frequency band corresponding to the low-frequency broadband dipole resonance peak, calculate the difference ΔT in the transmittance spectrum amplitude obtained from sample signals s1 and s2 as a characterization quantity for molecular fingerprint recognition, and determine the type of sample to be tested based on the characteristic peak frequency in the ΔT frequency response, thereby completing the qualitative identification of molecular fingerprint.

8. The measurement method of the functional multiplexing terahertz sensing system based on a split double-layer metasurface according to claim 7, characterized in that: The formula for calculating the transmittance spectrum in step S42 is as follows: in, The terahertz frequency domain amplitude spectrum of sample signal s1 or sample signal s2. The transmittance spectrum is for sample signal s1 or sample signal s2. Let r be the terahertz frequency domain amplitude spectrum of the reference signal r.

9. The measurement method of the functional multiplexing terahertz sensing system based on a split double-layer metasurface according to claim 7, characterized in that: The sensitivity calculation formula in step S43 is as follows: in, and These are the resonant frequencies of sample signals s1 and s2 within the frequency band corresponding to the high-frequency narrowband q-BIC resonance peak, respectively. denoted as the refractive index of the sample to be tested.

10. The measurement method of the functional multiplexing terahertz sensing system based on a split double-layer metasurface according to claim 7, characterized in that: The formula for calculating the transmittance spectrum amplitude difference ΔT in step S44 is as follows: in, and These are the transmittance spectra in the frequency band corresponding to the low-frequency broadband dipole resonance peak, calculated from sample signal s1 and sample signal s2, respectively.

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