Infrared liquid phase enhanced sensor based on plasmon BIC metasurface

Abstract

The invention relates to an infrared liquid phase enhanced sensor based on a plasmon BIC metasurface, the infrared liquid phase enhanced sensor comprises a microfluidic splint layer and a metasurface sample layer, a closed microfluidic cavity is arranged in the metasurface sample layer, a micro-nano structure is arranged on one side, facing the microfluidic cavity, of a metasurface sample of the metasurface sample layer, and the micro-nano structure is arranged on the other side of the metasurface sample of the metasurface sample layer. The micro-nano structure is composed of a plurality of repetitive units distributed in a periodic array, each repetitive unit is a pair of elliptical plates in mirror symmetry, the elliptical plates rotate around the centers of the repetitive units in the reverse direction at the same angle to break symmetry, and a quasi-BIC mode is excited. Through symmetrical breaking, a strong light field local enhancement effect is brought, interaction between light and liquid phase molecules is enhanced, the detection sensitivity is remarkably improved, the micron-sized cavity can inhibit water background absorption interference and adapt to a transmission and reflection dual-measurement mode, and structural parameters can be flexibly adjusted to adapt to detection of different target molecules.

Description

Technical Field

[0001] This invention relates to sensing technology, and more specifically to an infrared liquid-phase enhanced sensor based on a plasmonic BIC metasurface. Background Technology

[0002] Infrared spectroscopy, with its advantages of non-destructive detection and real-time response, has been widely used in many fields such as biochemical analysis, environmental monitoring, and water quality assessment. The functional activity of biomolecules is highly dependent on their aqueous solution environment; therefore, the infrared spectral study of target molecules in liquid systems is of paramount importance.

[0003] However, in practical molecular detection in liquid environments, traditional infrared spectroscopy faces two major limitations: firstly, aqueous solutions exhibit strong background absorption of infrared light, creating intense background interference that severely masks the characteristic spectral signals of the target molecules; secondly, there is a significant mismatch between the wavelength of infrared light and the size of molecules in the liquid system, resulting in extremely weak interaction between infrared light and target molecules, thus leading to low detection sensitivity. These problems severely restrict the application effectiveness of traditional infrared spectroscopy in practical scenarios such as bioanalysis, environmental monitoring, and water body detection.

[0004] To address the aforementioned issues, the industry has proposed utilizing the subwavelength structural characteristics of plasmonic metasurfaces to enhance the interaction between light and matter through electromagnetic field enhancement, providing a potential solution for developing high-performance infrared sensors. However, existing infrared liquid-phase detection technologies based on plasmonic metasurfaces still have significant technical shortcomings, specifically:

[0005] First, existing plasmonic metasurface devices generally suffer from high losses, resulting in low quality factors (Q values) of their resonance modes, making it difficult to further improve the detection sensitivity of trace target substances.

[0006] Secondly, in the infrared spectroscopy measurement of conventional molecules, the transmission mode is a common way to obtain high signal-to-noise ratio signals. However, most existing metasurface-based sensor devices only support the reflection mode. When detecting low reflectivity solutions, they are prone to weak signals and cannot meet the application requirements of conventional transmission measurements, which greatly limits the applicable scenarios and measurement accuracy of the devices.

[0007] Third, the structural design of existing metasurface devices lacks efficient and universal theoretical guidance and design principles, often relying on time-consuming and laborious parameter trial and error methods, resulting in insufficient structural flexibility and difficulty in adapting to different detection needs and application scenarios. Summary of the Invention

[0008] To address the significant technical bottlenecks in existing infrared liquid phase detection methods regarding detection sensitivity, measurement mode applicability, and structural design efficiency, this invention aims to provide an infrared liquid phase enhancement sensor based on a plasmonic BIC metasurface.

[0009] The infrared liquid-phase enhancement sensor based on a plasmonic binomial ionization (BIC) metasurface according to the present invention includes a microfluidic clamping layer providing mechanical support and sealing pressure, and a metasurface sample layer located inside the microfluidic clamping layer; the metasurface sample layer has a sealed microfluidic cavity, the metasurface sample layer includes a metasurface sample, and the side of the metasurface sample facing the microfluidic cavity has a micro / nano structure, the micro / nano structure is composed of a plurality of repeating units arranged in a periodic array, each repeating unit being a pair of mirror-symmetric elliptical disks; by rotating the elliptical disks around the geometric center of the repeating unit in opposite directions by the same angle, the original rotational symmetry is broken to excite a quasi-BIC mode, adapting to transmission measurement mode and reflection measurement mode.

[0010] In a preferred embodiment, the rotation angle of the elliptical disk is 5° to 35°, wherein a rotation angle of 20° is suitable for the transmission measurement mode, and a rotation angle of 30° is suitable for the reflection measurement mode.

[0011] In a preferred embodiment, the period of the repeating unit in the X and Y directions is 3μm to 3.5μm.

[0012] In a preferred embodiment, the center-to-center distance between the pair of elliptical disks is 1.5 μm to 1.7 μm.

[0013] In a preferred embodiment, the major axis of the elliptical disk is 1.7μm to 1.9μm, and the minor axis is 0.3μm to 0.4μm.

[0014] In a preferred embodiment, the micro / nano structure is deposited on a calcium fluoride substrate, the elliptical disk of the repeating unit is a gold elliptical disk with a thickness of nanometers, and an adhesion layer is provided between the gold elliptical disk and the calcium fluoride substrate, the adhesion layer being made of chromium or titanium.

[0015] In a preferred embodiment, the thickness of the gold elliptical disk is 30-100 nm, and the thickness of the adhesive layer is 3 nm.

[0016] In a preferred embodiment, the microfluidic clamping layer includes an upper clamping layer and a lower clamping layer arranged correspondingly above and below, and the metasurface sample layer is located between the upper clamping layer and the lower clamping layer. Mechanical pressure is achieved by uniformly tightening the screws at the edges of the upper clamping layer and the lower clamping layer.

[0017] In a preferred embodiment, the metasurface sample layer further includes an annular Mylar film layer and a calcium fluoride window, with the metasurface sample and the calcium fluoride window arranged vertically corresponding to each other, and the Mylar film layer disposed between them as a spacer layer. The microfluidic cavity is jointly defined by the lower surface of the metasurface sample, the inner surface of the Mylar film layer, and the upper surface of the calcium fluoride window.

[0018] In a preferred embodiment, the thickness of the microfluidic cavity is on the micrometer scale.

[0019] In a preferred embodiment, the thickness of the microfluidic cavity is less than 5 μm.

[0020] This invention utilizes a synergistic design of a microfluidic clamping layer and a metasurface sample layer, combined with the reverse rotation of mirror-symmetric elliptical disks in the repeating unit to achieve symmetry breaking. This successfully excites a quasi-BIC mode and brings about a strong local enhancement effect of the light field, effectively strengthening the interaction between infrared light and liquid molecules and significantly improving detection sensitivity. Simultaneously, it cleverly adapts to both transmission and reflection measurement modes, breaking the limitation of traditional sensors with a single measurement mode. The combination of a micron-level sealed microfluidic cavity and a metasurface structure further suppresses background absorption interference from aqueous solutions. The periodic array of elliptical disks and the flexibly adjustable geometric parameters allow the sensor to adapt to the detection needs of different target molecules. The overall structure is simple and highly practical, effectively solving the technical problems of low sensitivity, large water background interference, limited measurement modes, and insufficient structural flexibility in existing infrared liquid phase detection. It provides an efficient and reliable solution for the detection of trace components in complex liquid phase systems in fields such as biochemical analysis and environmental monitoring. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the infrared liquid-phase enhancement sensor based on the plasmon BIC metasurface according to the present invention.

[0022] Figure 2 yes Figure 1 Exploded view.

[0023] Figure 3 yes Figure 2 A schematic diagram of the structure of the metasurface sample.

[0024] Figure 4 yes Figure 3 A schematic diagram of the repeating unit of the micro / nano structure.

[0025] Figure 5 This is a schematic diagram of the results of measuring a microfluidic cavity using thin-film interferometry.

[0026] Figure 6 A schematic diagram showing the comparison results of transmission spectra of water layers with different thicknesses is presented.

[0027] Figure 7 This is a schematic diagram comparing the transmission spectra of the metasurface structure under different rotation angles with the transmission spectra after spin-coating PMMA.

[0028] Figure 8 This is a schematic diagram comparing the reflection spectra of the metasurface structure under different rotation angles with the reflection spectra after spin-coating PMMA.

[0029] Figure 9 This is a schematic diagram showing the relationship between the changes in transmission and reflection and the rotation angle.

[0030] Figure 10 This is a schematic diagram of the transmission spectrum under the optimal transmission measurement mode in a pure water environment.

[0031] Figure 11 This is a schematic diagram of the reflectance spectrum under the optimal reflectance measurement mode in a pure water environment.

[0032] Figure 12 This is a schematic diagram of the difference spectrum between the transmission spectrum and the pure water background in ethanol solutions of different concentrations without metasurface enhancement.

[0033] Figure 13 This is a schematic diagram of the difference spectrum between the transmission spectrum and the pure water background in ethanol solutions of different concentrations under metasurface enhancement.

[0034] Figure 14 This is a schematic diagram of the concentration detection limit analysis results of ethanol solution in transmission measurement mode.

[0035] Figure 15 This is a schematic diagram of the concentration detection limit analysis results of ethanol solution in reflectance measurement mode. Detailed Implementation

[0036] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0037] In this document, the terms “upper,” “lower,” “inner,” “outer,” “X direction,” “Y direction,” etc., are used only to describe orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0038] In this paper, bound states in the continuous domain (BIC) are localized electromagnetic states formed by the combined effects of specific symmetries or phase conditions. Since their theoretical models were proposed and experimentally verified to be stable in artificial microstructures, they have attracted widespread attention due to their unique optical field localization characteristics and radiation suppression mechanisms. Introducing BIC localization modes into the infrared liquid phase detection scenario of plasmonic metasurfaces can significantly enhance the local electric field intensity of the metasurface by controlling the symmetry of the metasurface's subwavelength structure, thereby achieving enhanced infrared response to solution molecules near the metasurface. This invention is based on the strong near-field coupling effect of plasmonic metasurfaces and the radiation suppression characteristics of BICs, combined with microfluidic technology, to construct a highly sensitive infrared liquid phase sensor compatible with both transmission and reflection measurement modes.

[0039] like Figures 1-2 As shown, the infrared liquid-phase enhancement sensor based on a plasmonic BIC metasurface according to the present invention includes a microfluidic clamping layer 100 and a metasurface sample layer 200. The microfluidic clamping layer 100 serves as the outer structure, providing mechanical support and applying sealing pressure to the entire sensor. The metasurface sample layer 200, located in the central region of the microfluidic clamping layer 100, is the core functional layer for infrared sensing. The interior of the metasurface sample layer 200 provides a sealed microfluidic cavity, within which the liquid phase to be measured interacts with the metasurface structure, completing the generation and transmission of spectral signals.

[0040] The microfluidic clamping layer 100 is composed of a symmetrical upper clamping layer 101 and a lower clamping layer 102, with the metasurface sample layer 200 located between them. Both the upper clamping layer 101 and the lower clamping layer 102 are square stainless steel plates, possessing good mechanical strength and sealing performance. Four threaded holes are evenly distributed on their surfaces. Axial pressure is applied by tightening the upper clamping layer 101 and the lower clamping layer 102 with four screws, causing the components of the internal metasurface sample layer 200 to fit tightly together to form a microfluidic cavity. This also fixes the overall position of the metasurface sample layer 200, preventing assembly deviations from affecting the sensing effect.

[0041] The metasurface sample layer 200 includes a metasurface sample 202, a Mylar membrane layer 203, and a calcium fluoride window 204. The metasurface sample 202 and the calcium fluoride window 204 are arranged vertically opposite each other. The Mylar membrane layer 203 is annular and positioned between the metasurface sample 202 and the calcium fluoride window 204 as a spacer. The microfluidic cavity is defined by the lower surface of the metasurface sample 202, the inner surface of the Mylar membrane layer 203, and the upper surface of the calcium fluoride window 204. Additionally, the metasurface sample layer 200 includes two silicone conduits 201, which penetrate the metasurface sample 202 to guide the analyte liquid phase into or out of the microfluidic cavity. It should be understood that the silicone conduits 201 extend upwards through corresponding openings in the upper clamping layer 101 of the microfluidic clamping layer 100, enabling the injection and evacuation of the analyte liquid phase. The calcium fluoride window 204 serves as an infrared light-transmitting window. Its material has good mid-infrared light transmittance, which allows the infrared detection light to pass through without loss, sequentially through the liquid phase to be tested in the microfluidic cavity, and irradiate the metasurface structure on the metasurface sample 202, while avoiding interference with the detection signal.

[0042] like Figures 3-4 As shown, the metasurface sample 202 includes a calcium fluoride substrate and a micro / nano structure 300 deposited on the calcium fluoride substrate as a sensing region, i.e., a metasurface structure. The micro / nano structure 300 is arranged in a periodic array, which consists of several repeating units 400. The periodic arrangement of the structure ensures that a uniform electromagnetic field enhancement effect is formed when infrared light interacts with the metasurface, avoiding local signal fluctuations.

[0043] Each repeating unit 400 has a thickness of 53 nm, comprising a 3 nm thick chromium (Cr) adhesive layer and a 50 nm thick gold (Au) structural layer. The Cr adhesive layer enhances the bonding between the Au structural layer and the calcium fluoride substrate. It should be understood that the Cr adhesive layer can be replaced with other adhesive materials such as Ti. The thickness described here is merely an example and not a limitation; for example, the thickness of the Au structural layer could be 30-100 nm, while the 3 nm thickness of the Cr adhesive layer remains unchanged.

[0044] Each repeating unit 400 consists of a pair of mirror-symmetric elliptical disks. In the unrotated state, the major axes of the two elliptical disks are arranged along the Y-axis (vertical line), exhibiting strict rotational symmetry, which lays the foundation for subsequent excitation of BIC modes through symmetry breaking.

[0045] In this embodiment, the period of the repeating unit 400 is 3.2 μm in both the X and Y directions, the center-to-center distance between the two elliptical disks is 1.6 μm, and the major axis of the elliptical disks is 1.8 μm and the minor axis is 0.36 μm. It should be understood that these dimensions are for the mid-infrared band at 1650 cm⁻¹. -1The water absorption peak at the target molecule is optimized and can be flexibly adjusted according to the characteristic absorption frequency band of the target molecule. For example, the period of the repeating unit in the X and Y directions is 3μm~3.5μm, the center distance between a pair of elliptical disks is 1.5μm~1.7μm, the major axis dimension of the elliptical disk is 1.7μm~1.9μm, and the minor axis dimension is 0.3μm~0.4μm.

[0046] The Mylar membrane layer 203, in conjunction with the microfluidic clamping layer 100, seals the microfluidic cavity and also limits its basic thickness. The thickness of the microfluidic cavity is on the order of micrometers, determined by the thickness of the Mylar membrane layer 203 and the axial pressure applied to the microfluidic clamping layer 100 via screws. This invention employs thin-film interferometry to measure the actual thickness of the microfluidic cavity. Figure 5 As shown, according to the thin film interference formula: k(cm) -1 ) = 10000 / 2nL, where k is the period of the reflection spectrum, n is the refractive index of the cavity, and L is the thickness of the cavity. The calculated actual thickness of the microfluidic cavity is approximately 5 μm. For example... Figure 6 As shown, when the water layer thickness is approximately 10 μm, at a depth of 1650 cm... -1 (Infrared light cannot penetrate the liquid to complete the detection in the strong absorption band of water molecules. Therefore, the thickness of the microfluidic cavity of the present invention is preferably within 5 μm.

[0047] Specifically, by breaking the rotational symmetry of the repeating unit 400, this invention can transform a non-radiative intrinsic BIC mode into a radiation-controllable quasi-BIC mode. The radiation loss and quality factor (Q value) of this quasi-BIC mode can be precisely controlled by the degree of symmetry breaking, thereby optimizing the interaction strength between the light field and liquid phase molecules. Specifically, this invention achieves symmetry breaking by rotating the elliptical disks in the repeating unit 400. The rotation angle is defined as the angle between the principal axis (major axis) of the elliptical disk and the Y-axis. That is, by rotating a pair of mirror-symmetrical elliptical disks relative to each other by a certain angle, the original rotational symmetry is broken. Specifically, by rotating a pair of mirror-symmetrical elliptical disks in the repeating unit 400 in opposite directions by the same angle around the geometric center of the repeating unit 400, the original rotational symmetry is broken. The rotation angle is defined as the angle between the principal axis (major axis) of the elliptical disk and the Y-axis.

[0048] Spin-coating polymethyl methacrylate (PMMA) simulates the adsorption of target molecules to verify the interaction strength between the light field and matter at different rotation angles, such as... Figures 7-9As shown, the changes in transmittance and reflectance spectra differ significantly with different rotation angles. When the rotation angle is set to 20°, the transmittance change reaches its maximum value. At this point, the light field enhancement in the quasi-BIC mode is mainly concentrated in the transmission direction, which is suitable for the transmission measurement mode. When the rotation angle is set to 30°, the reflectance change reaches its maximum value, and the light field enhancement is mainly concentrated in the reflection direction, which is suitable for the reflection measurement mode. It should be understood that the aforementioned 20° and 30° rotation angles are the optimal fitting angles corresponding to the repeating unit size (X / Y direction period 3.2μm, elliptical disk major axis 1.8μm / minor axis 0.36μm), material system (gold layer + chromium adhesion layer + calcium fluoride substrate), and experimental conditions in this embodiment, and are not fixed values. In practical applications, this optimal rotation angle will be adjusted according to changes in the geometric dimensions of the repeating unit (such as period, elliptical disk major and minor axis ratio), material parameters (such as metal layer thickness, substrate refractive index), and experimental environmental conditions, preferably within the rotation angle range of 5° to 35°. By selecting an appropriate angle within this range, light field enhancement and high-sensitivity detection can be achieved in either transmission or reflection modes, ensuring flexibility and universality.

[0049] Thus, by prefabricating metasurface samples 202 with different rotation angles and installing them into the modularly designed metasurface sample layer 200, the present invention can achieve flexible switching between transmission / reflection modes, overcome the shortcomings of existing metasurface sensors with a single measurement mode, and achieve flexible adaptation of angle adjustment → mode switching.

[0050] like Figures 10-11 As shown, in a pure water environment, at 1650cm -1 The presence of distinct characteristic peaks at the strong absorption sites of water molecules in the mid-infrared band indicates a strong coupling between water molecules and the plasmonic BIC metasurface structure. This strong coupling effect can amplify minute changes in trace substances into detectable signals, which is the core mechanism for achieving ultra-low concentration detection.

[0051] like Figure 12 As shown, without metasurface enhancement, the signal changes of low-concentration ethanol (e.g., 0.01%, 0.1%) are weak and almost masked by noise, making them impossible to effectively identify; Figure 13 As shown, with metasurface enhancement, in the low concentration range (0.0001%~1%), as the ethanol concentration increases, the 1650 cm⁻¹... -1 The difference spectral signal gradually increases because as the ethanol concentration increases, the water content in the solution decreases relatively, the absorption of water molecules weakens, and the transmittance difference changes accordingly, proving that the sensor can clearly capture the signal of low-concentration target molecules. The results show that the sensor of this invention can clearly capture the signal response of target molecules at different concentrations, and the signal discrimination in the low-concentration range is high, providing a foundation for high-sensitivity detection.

[0052] The detection limit is defined as the lowest concentration at which the signal exceeds 3σ (σ represents normal noise fluctuation, and 3σ is the detection limit threshold; noise interference can be excluded when the signal exceeds 3σ). Figure 14 As shown, when the ethanol concentration reaches 0.01% (volume fraction), the corresponding transmittance change signal just exceeds the 3σ threshold line, indicating that the lowest ethanol concentration that can be stably detected in transmission mode is 0.01%, which is significantly better than the detection limit of 0.5% without metasurface enhancement; Figure 15 As shown, the detection limit of the reflection mode is 5.5% (volume fraction), which is lower than that of the transmission mode, but it solves the problem that the reflection mode of low refractive index solutions cannot be detected in the prior art. Thus, the detection limit of the transmission mode of the present invention achieves an order-of-magnitude improvement (from 0.5% to 0.01%), which fully verifies the enhancement effect of the BIC metasurface and the practicality of the dual-mode design.

[0053] Thus, addressing the insufficient detection sensitivity caused by high loss and low quality factor (Q value) of resonant modes in existing plasmonic metasurface devices, this invention introduces a continuous domain bound state (BIC) mechanism. Utilizing the symmetry breaking of the elliptical disk's reverse rotation at the same angle, it excites a quasi-BIC mode with low radiation loss and a high quality factor (Q value). This mode can generate a strong local enhancement effect of the optical field in the metasurface's local space, significantly strengthening the interaction between infrared light and liquid molecules, thus breaking through the sensitivity bottleneck from a physical mechanism perspective. Furthermore, addressing the limitation of existing metasurface sensors that mostly support only reflection mode and have limited applicability, this invention clarifies the adaptation relationship between the rotation angle and the measurement mode (20° corresponds to transmission mode, 30° corresponds to reflection mode). Combined with the modular design of the metasurface sample, it achieves flexible switching between transmission and reflection modes. This satisfies the high signal-to-noise ratio signal requirement of conventional transmission measurements while solving the problem of weak detection signals in low-reflectivity solutions, significantly broadening the device's applicable scenarios. Furthermore, addressing the issues of existing metasurface device designs relying on parameter trial and error and lacking structural flexibility, this invention establishes a correlation between the rotation angle of the elliptical disk and the measurement mode. This allows for flexible adjustment based on the characteristic absorption frequency band of the target molecule, eliminating the need for time-consuming parameter trial and error. This approach can adapt to the detection requirements of different liquid phase systems, significantly improving structural flexibility and design efficiency.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. An infrared liquid-phase enhanced sensor based on a plasmonic BIC metasurface, characterized in that, This infrared liquid-phase enhanced sensor includes a microfluidic clamping layer providing mechanical support and sealing pressure, and a metasurface sample layer located inside the microfluidic clamping layer. The metasurface sample layer contains a sealed microfluidic cavity. The metasurface sample layer includes a metasurface sample, and a micro / nano structure is provided on the side of the metasurface sample facing the microfluidic cavity. The micro / nano structure consists of several repeating units arranged in a periodic array, each repeating unit being a pair of mirror-symmetric elliptical disks. By rotating the elliptical disks around the geometric center of the repeating unit in opposite directions by the same angle, the original rotational symmetry is broken to excite a quasi-BIC mode, adapting to both transmission and reflection measurement modes.

2. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The rotation angle of the elliptical disk is 5°~35°, wherein a rotation angle of 20° is suitable for transmission measurement mode, and a rotation angle of 30° is suitable for reflection measurement mode.

3. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The period of the repeating unit in the X and Y directions is 3μm~3.5μm.

4. The infrared liquid phase enhancement sensor according to claim 3, characterized in that, The center-to-center distance between the pair of elliptical disks is 1.5μm to 1.7μm.

5. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The major axis of the elliptical disk is 1.7μm~1.9μm, and the minor axis is 0.3μm~0.4μm.

6. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The micro / nano structure is deposited on a calcium fluoride substrate. The elliptical disk of the repeating unit is a gold elliptical disk with a thickness of nanometers. An adhesion layer is provided between the gold elliptical disk and the calcium fluoride substrate. The adhesion layer is made of chromium or titanium.

7. The infrared liquid phase enhancement sensor according to claim 6, characterized in that, The thickness of the gold elliptical disk is 30-100nm, and the thickness of the adhesive layer is 3nm.

8. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The microfluidic clamping layer includes an upper clamping layer and a lower clamping layer arranged correspondingly above and below each other. The metasurface sample layer is located between the upper clamping layer and the lower clamping layer. Mechanical pressure is achieved by uniformly tightening the screws at the edges of the upper clamping layer and the lower clamping layer.

9. The infrared liquid phase enhancement sensor according to claim 1, characterized in that, The metasurface sample layer also includes an annular Mylar film layer and a calcium fluoride window. The metasurface sample and the calcium fluoride window are arranged vertically and vertically, with the Mylar film layer placed between them as a spacer. The microfluidic cavity is defined by the lower surface of the metasurface sample, the inner surface of the Mylar film layer, and the upper surface of the calcium fluoride window.

10. The infrared liquid phase enhancement sensor according to claim 9, characterized in that, The thickness of the microfluidic cavity is less than 5 μm.

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