Trace detection method of rare earth ions, terahertz metamaterial chemical sensor and its application

Abstract

The present invention proposes a trace detection method for rare earth ions, a terahertz metamaterial chemical sensor and its application; based on the existing rare earth ion detection technology, which has the problems of long time consumption, expensive instruments and complex sample processing; the present invention combines terahertz metamaterials with rare earth ion imprinted nanomaterials, captures specific rare earth ions through rare earth ion imprinted nanospheres, and amplifies the terahertz signal of rare earth ions through BIC resonance, which can suppress noise interference, realize trace detection of rare earth ions at the nanomolar level and above, and significantly improve the selectivity and sensitivity of rare earth ion terahertz detection. Based on the above method, the present invention realizes the research and development of a quasi-BIC metamaterial array structure with rare earth ion imprinted nanomaterials attached, which can be applied to various terahertz detection systems to realize trace detection of rare earth ions, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of trace detection of rare earth ions, and in particular to a trace detection method of rare earth ions with high sensitivity and accurate detection, a terahertz metamaterial chemical sensor and applications thereof. Background Art

[0002] Rare earth elements refer to 15 elements (lanthanides) in the third subgroup of the periodic table with atomic numbers ranging from 57 (La) to 71 (Lu), as well as scandium (Sc) and yttrium (Y) with similar electronic structures and chemical properties. Rare earth elements have become the subject of extensive attention and exploration in today's scientific and industrial communities due to their unique 4f electronic structure, which gives them large atomic magnetic moments and strong spin-orbit coupling. With the large-scale development of rare earth resources, rare earth elements inevitably enter the ecological environment through various pathways. The concentration of rare earths in biological samples (such as animals and plants) is generally in the range of ppm–ppb (1×10 -6 – 1×10 -9 ) level; the rare earth concentration in environmental samples (such as air, water, soil, etc.) is in the range of ppm–ppt (1×10 -6 – 1×10 -12 The difficulty of rare earth detection lies in the similarity of chemical properties, so qualitative identification is difficult; and with the development of various disciplines, the detection limit requirements for rare earth impurities are getting lower and lower, so the accuracy and sensitivity of rare earth detection have become crucial.

[0003] At present, the commonly used methods for detecting rare earth ions are mainly atomic absorption spectroscopy, inductively coupled plasma mass spectrometry and neutron activation analysis. Among them, atomic absorption spectroscopy uses characteristic radiation emitted by atoms of the same kind to irradiate the atomized and atomized atomic vapor layer of the sample solution, measures the light intensity or absorbance of the characteristic radiation, and calculates the content of the measured element in the sample based on the relationship between absorbance and concentration. It has the advantages of simple operation and fast analysis, but is easily interfered when analyzing mixtures and is not suitable for the detection of mixed rare earth ions. Inductively coupled plasma mass spectrometry uses an inductively coupled plasma source as a high-temperature ion source to dissociate and atomize the sample, and uses a mass spectrometer to scan ions of specific element mass numbers to determine the type and content of rare earth ions. It has the advantages of high sensitivity and simultaneous detection of multiple elements, but the instrument is expensive, and the sample pretreatment and enrichment process are cumbersome and time-consuming. Neutron activation analysis is a method of using neutrons to bombard the isotopes of rare earth elements in the sample to produce nuclear reactions, and to perform qualitative and quantitative analysis of rare earth elements by measuring the prompt gamma generated. It has the advantages of high sensitivity and high accuracy, but the detection accuracy is easily interfered by uranium elements, and the sample preparation process is cumbersome and time-consuming. In summary, the existing rare earth ion detection technology has problems such as long time consumption, expensive instruments, and complex sample processing. Therefore, it is necessary to explore a fast, efficient, and accurate technology for the detection of rare earth ions. Summary of the invention

[0004] The purpose of the present invention is to propose a method and sensor that has the ability to selectively capture specific rare earth ions and amplify the terahertz signal of the rare earth ions through quasi-BIC resonance, thereby significantly improving the selectivity and sensitivity of terahertz detection of rare earth ions and realizing trace detection of rare earth ions.

[0005] To achieve the above objectives, the present invention proposes a method for trace detection of rare earth ions, which captures specific rare earth ions by rare earth ion imprinted nanospheres and amplifies the terahertz signals of rare earth ions by BIC resonance, thereby realizing trace detection of rare earth ions at the nanomolar level and above.

[0006] The present invention also proposes a terahertz metamaterial chemical sensor, comprising a quasi-BIC metamaterial unit array structure and a rare earth ion imprinted nanomaterial, wherein the rare earth ion imprinted nanomaterial is uniformly distributed on the surface of the quasi-BIC metamaterial unit array structure; the quasi-BIC metamaterial has a high Q value terahertz enhancement effect, and the magnetic rare earth ion imprinted nanospheres provide rare earth ion selective recognition sites, and the two are combined to form a highly sensitive and highly selective terahertz metamaterial chemical sensor.

[0007] Furthermore, the quasi-BIC metamaterial unit array structure is formed by aligning a plurality of identical quasi-BIC metamaterial units in the horizontal and vertical directions;

[0008] The quasi-BIC metamaterial unit includes a dielectric substrate and a resonator unit attached to the surface of the dielectric substrate; the resonator unit is a double-opening resonator that can induce a quasi-BIC resonance peak with an ultra-high Q value;

[0009] Furthermore, the double-opened resonator may be in various shapes, including a circular ring, a triangular ring, and a square ring;

[0010] The relative width of the two openings of the same double-opening resonator can be changed; the opening shape can be changed, including circular, triangular and rectangular; the opening position can be moved on the cantilever of the double-opening resonator. By introducing asymmetric perturbations to induce the appearance of quasi-BIC, a high-Q quasi-BIC resonance peak can be achieved in the frequency domain, and the peak position is consistent with the peak position of the target rare earth ion.

[0011] Furthermore, the dielectric substrate is made of a material with good transmittance in the terahertz band, including single crystal silicon, quartz or polyethylene;

[0012] The double-open resonator is prepared by mixed materials, including metal materials, dielectric materials and tunable materials; the metal materials include one or more of gold, silver, copper and aluminum; the dielectric materials are materials with good photoelectric response, including silicon; the tunable materials include one or more of graphene, vanadium dioxide and indium antimonide;

[0013] The Y-direction material and the X-direction material of the double-opened resonator may be different.

[0014] Furthermore, the rare earth ion imprinted nanomaterials include magnetic nanospheres and rare earth ion imprinted polymers; the rare earth ion imprinted polymers are attached to the surface of the magnetic nanospheres, and the attachment method includes deposition or coating; the rare earth ion imprinted nanomaterials are uniformly adsorbed on the surface of the quasi-BIC metamaterial unit array structure through the magnetic nanospheres. When the sample solution containing rare earth ions is dropped on the surface of the terahertz metamaterial chemical sensor, the rare earth ion imprinted nanomaterials selectively adsorb specific rare earth ions through functional groups and imprinted cavities.

[0015] Furthermore, the rare earth ion imprinted polymer comprises a base polymer, an imprinted cavity, and a functional group capable of complexing with the rare earth ion;

[0016] The base polymer is a material with high reaction efficiency, mild and controllable reaction conditions, and stable combination with magnetic nanospheres, including polyacrylic acid, polyethylene glycol or polyethyleneimine;

[0017] The imprinted cavity has a specific three-dimensional space that matches the size of the rare earth ions to be detected, achieving selective adsorption of rare earth ions;

[0018] The functional groups interact with the rare earth ions to be detected and together with the imprinted cavities achieve selective adsorption of the rare earth ions.

[0019] Furthermore, by adjusting the size and material of the magnetic nanospheres, the volume of the imprinted cavity, and the type of functional monomers, highly selective recognition of different types of rare earth ions can be achieved;

[0020] By adjusting the structural parameters and materials of the double-open resonator, high-Q terahertz resonance can be achieved.

[0021] The present invention also proposes an application of a terahertz metamaterial chemical sensor, which can be applied to a detection system to achieve trace detection of rare earth ions;

[0022] The detection system includes a terahertz emission module, a terahertz metamaterial chemical sensor loaded with a rare earth ion sample, a terahertz detection module, and a data processing and display module, which are sequentially placed on the same optical axis; the spectral range of the terahertz emission module and the spectral range of the terahertz detection module include and are greater than the working frequency range of the terahertz metamaterial chemical sensor.

[0023] Furthermore, the detection steps of the detection system are as follows:

[0024] S1: Take a clean and complete terahertz metamaterial chemical sensor, measure and record the quasi-BIC resonance frequency of the terahertz metamaterial chemical sensor;

[0025] S2: drop the rare earth ion sample to be tested on the surface of the terahertz metamaterial chemical sensor, then rinse with deionized water to remove the remaining interferences in the sample, and remove the free water molecules contained in the sample by vacuum drying;

[0026] S3: The terahertz metamaterial chemical sensor with rare earth ions on its surface is fixed on the sample holder according to the polarization direction requirements, and its absorption spectrum is measured by the terahertz detection module and recorded by the data processing and display module; when the terahertz wave passes through the magnetic imprinted nanomaterial and the terahertz metamaterial adsorbed with specific rare earth ions in turn, the dielectric constant of the sensor surface will change, which is manifested as the frequency shift and amplitude change of the sensor's quasi-BIC resonance peak.

[0027] S4: Perform the operation steps of S3 multiple times, read the terahertz resonance peak with rare earth ion information, record the frequency shift and amplitude change of the resonance peak, analyze the type and content of rare earth ions through the frequency shift and amplitude change, and calculate the rare earth ion concentration in the sample.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] The present invention constructs a terahertz metamaterial chemical sensor for the detection of trace amounts of rare earth ions, combining quasi-BIC terahertz metamaterials and rare earth ion imprinted nanomaterials. Rare earth ion imprinted nanomaterials can selectively adsorb target rare earth ions from the sample to be tested. Under the radiation of terahertz waves, the quasi-BIC terahertz metamaterial can achieve a quasi-BIC resonance peak with an ultra-high Q value. At the same time, the resonance frequency of the quasi-BIC resonance peak coincides with the terahertz characteristic absorption frequency of the target rare earth ion, and the resonance between the two is enhanced. Under the combined effect, the detection accuracy and recognition ability of the terahertz metamaterial chemical sensor for rare earth ions are greatly improved, effectively solving the current problem of difficulty in detecting trace ions;

[0030] 2. The metamaterial structure described in the present invention is easy to use, reusable, and adaptable to various terahertz detection systems. It is easy to operate, and the processing accuracy only requires micrometer level. The production process is mature and the cost is low. It can be mass-produced and has good commercial application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the quasi-BIC metamaterial unit structure in the present invention;

[0032] Figure 2 This is a schematic diagram of the rare earth ion imprinted nanomaterial in the present invention;

[0033] Figure 3 Schematic diagram of the rare earth ion imprinted polymer structure of the present invention;

[0034] Figure 4It is a schematic diagram of the structure of the terahertz metamaterial chemical sensor in the present invention;

[0035] Figure 5 It is a schematic diagram of the detection process of the terahertz metamaterial chemical sensor in the present invention;

[0036] Figure 6 The terahertz characteristic absorption peak of praseodymium oxide in the present invention and the quasi-BIC resonance peak of the terahertz metamaterial chemical sensor designed for praseodymium ions;

[0037] Figure 7 This is the detection result of praseodymium ions and other interferents by the terahertz metamaterial chemical sensor in the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be further described below.

[0039] Based on the existing rare earth ion detection technology in the background technology, there are problems such as long time consumption, expensive instruments and complex sample processing; this application combines terahertz metamaterials with rare earth ion imprinted nanomaterials to achieve high-sensitivity and high-precision detection of rare earth ions.

[0040] Terahertz waves are electromagnetic waves with a frequency range of 0.1–10 THz, located between microwaves and infrared, and are highly sensitive to low-frequency fingerprint information such as lattice vibrations and intermolecular interactions. This gives terahertz spectroscopy technology unique advantages in material characterization and component analysis. The combination of terahertz waves and metamaterials fully utilizes the characteristics of terahertz waves such as rich fingerprint information and coherent physical parameters, as well as the advantages of metamaterial devices such as rich electromagnetic modes and flexible functional design, and has been widely used in environmental monitoring, biomedicine, wireless communications and other fields. However, the lack of a selective recognition mechanism is the main bottleneck restricting the practical application of terahertz chemical sensors.

[0041] Ion-imprinted materials are "artificial antibodies" constructed by mimicking antibody-antigen interactions. Compared with natural antibodies, rare earth ion-imprinted nanomaterials have binding sites that interact with target ions and have three-dimensional cavities that match target ions, giving them the unique advantage of ion-selective recognition. This type of material has received significant attention in the field of optical sensing due to its simple preparation process, stable chemical properties, low cost, and easy storage. However, rare earth ion-imprinted materials have insufficient mechanical properties, which limits their application areas.

[0042] Therefore, the present invention proposes the following technical solutions:

[0043] like Figure 1The figure shows a schematic diagram of the quasi-BIC metamaterial unit structure. The metamaterial structural unit includes a dielectric substrate 1-1 and a resonator unit attached to its surface and connected to each other; the resonator unit includes two double-opening resonators 1-2 made of mixed materials, and the relative widths of the two openings 1-3 on the same double-opening resonator 1-2 are variable, and the position of the opening 1-3 can be moved on the cantilever of the double-opening resonator. The double-opening resonator unit can induce a quasi-BIC resonance peak with a high Q value; multiple identical quasi-BIC metamaterial units are aligned in the longitudinal and transverse directions, and finally form a complete quasi-BIC metamaterial unit array structure.

[0044] In this embodiment, the double-opening resonator 1-2 can be set to different configurations, including heterogeneous shapes such as circular rings, triangular rings, and square rings. Among them, the opening 1-3 can be set to different shapes, widths, and positions. The shapes include various openable shapes such as circles, triangles, and rectangles. The relative widths of the two openings on the same double-opening resonator 1-2 are variable, and the position of the opening 1-3 can be moved on the cantilever of the double-opening resonator 1-2. The double-opening resonator 1-2 uses mixed materials, including but not limited to different materials in the Y direction, different materials in the X direction, etc. The metal materials used include gold, silver, copper, aluminum, etc. The dielectric materials used include materials with good photoelectric response such as silicon, and the tunable materials used include graphene, vanadium dioxide, indium antimonide, and other photoelectric property tunable materials.

[0045] In this embodiment, the material used for the dielectric substrate 1 - 1 in the metamaterial structural unit includes single crystal silicon, quartz, polyethylene and other materials with good transmittance in the terahertz band.

[0046] like Figure 2 The diagram shows a schematic diagram of a rare earth ion imprinted nanomaterial. The rare earth ion imprinted nanomaterial comprises a magnetic nanosphere 2-1 and a rare earth ion imprinted polymer 2-2 attached to the surface thereof; the attachment method includes but is not limited to deposition, coating, etc.

[0047] like Figure 3 The diagram shows the structure of the rare earth ion imprinted polymer 2-2 attached to the surface of the magnetic nanosphere 2-1. The rare earth ion imprinted polymer 2-2 comprises a base polymer 3-1, an imprinted cavity 3-2 and a functional group 3-3 that can complex with the rare earth ion.

[0048] In this embodiment, the magnetic nanospheres 2 - 1 include but are not limited to nanomaterials composed of magnetic elements (such as iron, nickel, cobalt, chromium, manganese, gadolinium, etc.) and their compounds.

[0049] In this embodiment, the base polymer 3-1 adopts a material with high reaction efficiency, mild and controllable reaction conditions, and stable combination with magnetic nanospheres, including but not limited to polyacrylic acid, polyethylene glycol, polyethyleneimine, etc.; the imprinted cavity 3-2 has a specific three-dimensional space that matches the size of the rare earth ion to be detected, and can achieve selective adsorption of rare earth ions.

[0050] In this embodiment, the functional group 3-3 capable of complexing with the rare earth ions interacts with the rare earth ions to be detected, and together with the imprinted cavity 3-2, achieves the selective adsorption of the rare earth ions.

[0051] like Figure 4 The figure shows the schematic diagram of the structure of the terahertz metamaterial chemical sensor. A plurality of identical quasi-BIC metamaterial structural units are aligned in the longitudinal and transverse directions to finally form a complete quasi-BIC metamaterial unit array structure 4-1, and at the same time, the magnetic rare earth ion imprinted nanospheres 4-2 are evenly distributed on the surface of the quasi-BIC metamaterial unit array structure 4-1, and the surface of the magnetic rare earth ion imprinted nanospheres has a plurality of rare earth ion imprinted vacancies 4-3.

[0052] like Figure 5 The detection process diagram of the terahertz metamaterial chemical sensor for detecting rare earth ions shown in the figure includes a terahertz emission module 5-1 placed in the same optical axis, a terahertz chemical sensor 5-2 loaded with a rare earth ion sample, a terahertz detection module 5-3, and a data processing and display module 5-4. The spectral range of the terahertz emission module and the spectral range of the terahertz detection module should include and be greater than the working frequency range of the metamaterial chemical sensor.

[0053] First, the metamaterial is fixed on the sample holder according to its polarization direction and aligned with the terahertz wave. The terahertz wave is generated by the terahertz emission module 5-1, vertically incident and passes through the loaded terahertz chemical sensor 5-2, and then vertically incident and passes through the rare earth ion imprinted nanomaterial and the quasi-BIC metamaterial, and is finally detected by the terahertz detection module 5-3. An obvious terahertz resonance peak reference signal will appear through the data processing and display module 5-4. Then the rare earth ion sample is dropped on the surface of the terahertz chemical sensor 5-2, the target rare earth ions are captured by the rare earth ion imprinted nanomaterial, and the remaining interferences are removed by rinsing with deionized water and dried for testing. Next, the metamaterial chip with the rare earth ions to be tested is fixed on the sample holder again according to the polarization direction requirements. The terahertz wave is generated by the terahertz emission module 5-1, and passes through the rare earth ion imprinted nanomaterial and the terahertz metamaterial that adsorb rare earth ions in turn. The change in the dielectric constant on the sensor surface is finally detected by the terahertz detection module 5-3, and a terahertz resonance peak sample signal with the rare earth information to be measured is obtained. The rare earth ion imprinted nanomaterial has selective recognition of specific rare earth ions, and the structural unit array composed of double-open resonators in the metamaterial only absorbs terahertz waves of specific frequencies, forming a high-Q quasi-BIC resonance peak. When a rare earth ion sample is dripped on the surface of the designed terahertz metamaterial chemical sensor, the selective absorption characteristics of the metamaterial for terahertz waves change, which is manifested as a shift in the position of the terahertz resonance peak and a change in the amplitude. These changes directly reflect the difference in sample type and concentration. Compare the reference signal and the sample signal, read the terahertz resonance peak frequency shift and amplitude change obtained by the two acquisitions in the data processing and display module 5-4, and obtain the concentration of the rare earth ion to be measured through mathematical processing.

[0054] Next, the technical effect of the present invention will be further discussed by taking the specific detection of praseodymium ions as an example.

[0055] The present invention will be described in detail by taking praseodymium ion as an example. Figure 6 It is the terahertz characteristic absorption peak of praseodymium oxide and the quasi-BIC resonance peak of the terahertz metamaterial chemical sensor designed for praseodymium ions. Figure 7The detection results of the terahertz metamaterial chemical sensor for praseodymium ions and other interferents. In this embodiment, the material of the metamaterial dielectric substrate 1-1 is quartz with a thickness of 500 µm; the resonant unit is a rectangle with a side length of 80×50 µm, including two double-opening resonators 1-2; the material of the double-opening resonator is a combination of gold and dielectric material with a thickness of 100 nm; the widths of the double openings are 2 µm and 3 µm respectively, and both openings are rectangular. The surface geometry is prepared by photolithography and etching processes. Rare earth ion imprinted nanospheres are prepared by surface imprinting technology. The rare earth ion imprinted nanospheres are uniformly attached to the surface of the quasi-BIC metamaterial by spraying. The side length of the obtained terahertz metamaterial chemical sensor is 10 mm. The dielectric substrate can be replaced by other materials with good transmittance in the terahertz band, and the material of the double-opening resonator can be replaced by a combination of other metal materials, dielectric materials and tunable materials. All the above parameters are designed and processed according to the terahertz absorption spectrum characteristics of the target rare earth ions. In this embodiment, the resonant frequency band of the terahertz metamaterial chemical sensor is designed for the absorption peak of praseodymium ions at 5.73 THz, and the implementation method for enhancing the absorption of characteristic peaks of other rare earth ions in the terahertz band is consistent with this implementation method.

[0056] The terahertz transmitting module 5-1 outputs a signal with a frequency of 0-7 THz, and the terahertz detecting module 5-3 detects a signal with a frequency of 0-7 THz.

[0057] The first step is to take a clean and complete terahertz metamaterial chemical sensor, such as Figure 4 As shown, it is fixed on the sample holder according to the polarization direction requirement, and its absorption spectrum is measured by the terahertz detection module 5-3 and recorded by the data processing and display module 5-4; at this time, the quasi-BIC resonance frequency of the terahertz metamaterial chemical sensor is at 5.73 THz, as shown in Figure 6 As shown in b.

[0058] In the second step, 10 μL of the praseodymium ion sample to be tested is dropped onto the clean and complete surface of the terahertz metamaterial chemical sensor, and then the remaining interferences in the sample are removed by rinsing with deionized water, and the free water molecules contained in the sample are removed by vacuum drying;

[0059] The third step is to fix the terahertz metamaterial chemical sensor with praseodymium ions on the surface on the sample holder according to the polarization direction requirement, measure its absorption spectrum by using the terahertz detection module 5-3, and record it by the data processing and display module 5-4;

[0060] Step 4: Repeat the operation of step 3 for multiple times to read the terahertz resonance peak with praseodymium ion information, record the frequency shift and amplitude change of the resonance peak, and calculate the praseodymium ion concentration in the sample;

[0061] Step 5: Replace the praseodymium ions with other interfering ions and repeat the above operation;

[0062] The sixth step is to compare the THz resonance peak frequency shift response curves caused by different concentrations of praseodymium ions and interfering ions, such as Figure 7 As shown. In the praseodymium ion solution test, the resonance peak of the terahertz metamaterial chemical sensor is significantly enhanced at 5.73 THz, and the frequency shift changes significantly with the praseodymium ion concentration. In contrast, the resonance peak frequency of the sensor remains basically unchanged when the interfering ion solution is used for the same operation. This test result verifies the selective recognition and highly sensitive detection capability of the terahertz metamaterial chemical sensor designed for praseodymium ion detection.

[0063] By adjusting the size and material of the magnetic nanospheres, the volume of the imprinted cavity, and the type of functional monomer, the sensor can achieve highly selective recognition of different types of rare earth ions. By adjusting the structural parameters and materials of the resonant unit, the sensor can achieve terahertz resonance with a high Q value. The combination of the two can accurately detect rare earth ion samples as low as nanomolar levels.

[0064] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A method for detecting trace amounts of rare earth ions, characterized in that: Specific rare earth ions are captured by rare earth ion imprinted nanospheres, and the terahertz signal of rare earth ions is amplified by BIC resonance, thus achieving trace detection of rare earth ions at the nanomolar level and above. The rare earth ion imprinted nanospheres include magnetic nanospheres and rare earth ion imprinted polymers; the rare earth ion imprinted polymers are attached to the surface of the magnetic nanospheres; the rare earth ion imprinted nanospheres are uniformly adsorbed on the surface of the quasi-BIC metamaterial unit array structure through the magnetic nanospheres; The rare earth ion imprinted polymer comprises a base polymer, an imprinted cavity and a functional group capable of complexing with the rare earth ion; The base polymer is a material with high reaction efficiency, mild and controllable reaction conditions, and stable combination with magnetic nanospheres; The imprinted cavity has a specific three-dimensional space that matches the size of the rare earth ion to be detected, thereby achieving selective adsorption of the rare earth ion; the functional group interacts with the rare earth ion to be detected, and together with the imprinted cavity, achieves selective adsorption of the rare earth ion; The quasi-BIC metamaterial unit includes a dielectric substrate and a resonator unit attached to the surface of the dielectric substrate; the resonator unit is a double-opening resonator.

2. A terahertz metamaterial chemical sensor, used in the trace detection method of rare earth ions as claimed in claim 1, characterized in that: It comprises a quasi-BIC metamaterial unit array structure and rare earth ion imprinted nanospheres, wherein the rare earth ion imprinted nanospheres are uniformly distributed on the surface of the quasi-BIC metamaterial unit array structure; The quasi-BIC metamaterial unit includes a dielectric substrate and a resonator unit attached to the surface of the dielectric substrate; the resonator unit is a double-opening resonator; The rare earth ion imprinted nanospheres include magnetic nanospheres and rare earth ion imprinted polymers; the rare earth ion imprinted polymers are attached to the surface of the magnetic nanospheres; The rare earth ion imprinted polymer comprises a base polymer, an imprinted cavity and a functional group capable of complexing with the rare earth ion; The base polymer is a material with high reaction efficiency, mild and controllable reaction conditions, and stable combination with magnetic nanospheres; The imprinted cavity has a specific three-dimensional space that matches the size of the rare earth ions to be detected, thereby achieving selective adsorption of the rare earth ions; The functional group interacts with the rare earth ions to be detected, and together with the imprinted cavity, achieves selective adsorption of the rare earth ions.

3. The terahertz metamaterial chemical sensor according to claim 2, characterized in that: The quasi-BIC metamaterial unit array structure is formed by arranging a plurality of identical quasi-BIC metamaterial units in a horizontal and vertical direction.

4. The terahertz metamaterial chemical sensor according to claim 3, characterized in that: The double-open resonator is in the shape of a circular ring, a triangular ring or a square ring; The relative widths of the two openings of the same double-opening resonator can be varied; The opening position can be moved on the cantilever of the double-opening resonator.

5. The terahertz metamaterial chemical sensor according to claim 3, characterized in that: The dielectric substrate is made of a material with good terahertz band transmittance, including single crystal silicon, quartz or polyethylene; The double-open resonator is prepared by mixed materials, including metal materials, dielectric materials and tunable materials; the metal materials include one or more of gold, silver, copper and aluminum; the dielectric materials are materials with good photoelectric response, including silicon; the tunable materials include one or more of graphene, vanadium dioxide and indium antimonide; The Y-direction material and the X-direction material of the double-opening resonator are different or the same.

6. The terahertz metamaterial chemical sensor according to claim 2, characterized in that: The attachment method includes deposition or coating; the rare earth ion imprinted nanospheres are uniformly adsorbed on the surface of the quasi-BIC metamaterial unit array structure through the magnetic nanospheres.

7. The terahertz metamaterial chemical sensor according to claim 6, characterized in that: The base polymer includes polyacrylic acid, polyethylene glycol or polyethyleneimine.

8. The terahertz metamaterial chemical sensor according to claim 7, characterized in that: By adjusting the size and material of the magnetic nanospheres, the volume of the imprinted cavity and the type of functional groups, highly selective recognition of different types of rare earth ions can be achieved; By adjusting the structural parameters and materials of the double-opening resonator, a high-Q terahertz resonance can be achieved.

9. An application of a terahertz metamaterial chemical sensor, using the terahertz metamaterial chemical sensor as claimed in claim 2, characterized in that: After being applied to the detection system, it can realize the trace detection of rare earth ions; The detection system includes a terahertz emission module, a terahertz metamaterial chemical sensor loaded with a rare earth ion sample, a terahertz detection module, and a data processing and display module, which are sequentially placed on the same optical axis; the spectral range of the terahertz emission module and the spectral range of the terahertz detection module include and are greater than the operating frequency range of the terahertz metamaterial chemical sensor.

10. The use of the terahertz metamaterial chemical sensor according to claim 9, characterized in that: The detection steps of the detection system are as follows: S1: Take a clean and complete terahertz metamaterial chemical sensor, measure and record the quasi-BIC resonance frequency of the terahertz metamaterial chemical sensor; S2: dropping a rare earth ion sample to be tested on the surface of the terahertz metamaterial chemical sensor, then washing with deionized water to remove the remaining interferences in the sample, and removing free water molecules contained in the sample by vacuum drying; S3: Fix the terahertz metamaterial chemical sensor with rare earth ions loaded on the surface on the sample holder according to the polarization direction requirement, measure its absorption spectrum by using the terahertz detection module, and record it by the data processing and display module; S4: Perform the operation steps of S3 multiple times, read the terahertz resonance peak with rare earth ion information, record the resonance peak frequency shift and amplitude change, and calculate the rare earth ion concentration in the sample.

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