High-sensitivity sensing film based on niobium diselenide layered material

Abstract

The invention discloses a high-sensitivity sensing film based on a niobium diselenide (NbSe2) layered material, and belongs to the technical field of optical devices. The high-sensitivity sensing film sequentially comprises a transparent substrate, a gold film and niobium diselenide sensitive coatings from bottom to top, and the number of layers of the niobium diselenide sensitive coatings is 1-6. The surface of the gold film is coated with niobium diselenide, and electrons in the niobium diselenide material can be transferred to the metal surface, so that the concentration of free electrons on the metal surface is enhanced, the electric field intensity of a sensing interface is improved, and finally the sensibilization effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of optical device technology, and in particular relates to a highly sensitive sensing film based on niobium diselenide layered material. Background Technology

[0002] Surface plasmon resonance (SPR) sensors are optical sensing technologies that utilize the interaction between light and plasmons on a metal surface. These sensors feature high sensitivity, high resolution, and real-time monitoring, and are widely used in fields such as biochemical analysis, environmental monitoring, food safety testing, and medical diagnostics. The working principle of SPR sensors is based on the interaction between light waves and the free electron cloud on a metal surface (such as gold or silver), forming surface plasmon waves (SPPs). When the frequency of the incident light matches the resonant frequency of the SPPs, energy coupling occurs, leading to attenuation of the light wave; this coupling phenomenon is called surface plasmon resonance.

[0003] SPR sensors typically achieve light coupling with SPPs in two ways: substrate coupling and prism coupling. Substrate coupling involves depositing a metal film on a transparent substrate, utilizing the difference in refractive index between the substrate and the metal film to achieve coupling. Prism coupling, on the other hand, generates surface plasmon resonance waves between a prism and the metal film through total internal reflection. When surface plasmon resonance occurs, a specific resonance signal is formed. This signal usually manifests as a significant change in light intensity, which can be detected by a photodetector and converted into an electrical signal. The intensity and location of the resonance signal are highly sensitive to changes in the refractive index of the metal surface. The resonance signal of an SPR sensor is also highly sensitive to subtle changes in the surrounding environment (such as temperature, humidity, and chemical concentrations). Changes in these environmental parameters cause changes in the refractive index of the metal surface, resulting in changes in the resonance signal. By monitoring these changes, real-time and effective monitoring of environmental changes can be achieved.

[0004] Surface plasmon resonance (SPR) sensors are widely used in biosensing and chemical detection due to their high sensitivity and real-time monitoring capabilities. However, when faced with low concentrations of analytes or certain weak biochemical reactions, the sensitivity of conventional SPR sensors is insufficient, limiting their performance in certain applications. The sensitivity of conventional SPR sensors is limited by several factors, including the thickness of the metal thin film, coupling efficiency, the noise level of the detection system, and sample preparation and fixation methods. These factors collectively determine the sensor's ability to detect minute changes.

[0005] To address this challenge, researchers have developed various strategies to enhance the detection sensitivity of SPR sensors. These strategies include signal amplification techniques, such as using nanoparticles to enhance the SPR signal, employing multi-stage amplification systems, or improving selectivity for specific molecules through molecular imprinting. Furthermore, surface modification techniques, such as self-assembled monolayers (SAMs) or affinity layers, can increase the affinity of the sensor surface for specific analytes, thereby enhancing the signal response. Improving optical design, such as using high-performance light sources, optimizing optical path design, and employing high-sensitivity detectors, can also improve the detection capability of SPR sensors. Simultaneously, developing novel SPR-active materials, such as two-dimensional materials with unique electronic structures or conductive polymers, can provide higher sensitivity and selectivity. However, in practical applications, improving the sensitivity of SPR sensors also requires consideration of factors such as sample complexity, ease of operation, and cost-effectiveness. Therefore, future research will focus on the development of novel materials, innovation in signal amplification mechanisms, optimization of optical systems, and improvement of data processing algorithms to achieve highly sensitive detection of low-concentration analytes or weak biochemical reactions. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a highly sensitive sensing film based on niobium diselenide layered material. This aims to overcome the insufficient detection sensitivity of existing surface plasmon resonance (SPR) techniques.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the objectives of this invention is to provide a highly sensitive sensing membrane based on niobium diselenide layered material, which comprises, from bottom to top: a transparent substrate, a gold film, and a niobium diselenide sensitive coating, wherein the number of layers of the niobium diselenide sensitive coating is 1-6.

[0008] This invention achieves enhanced sensitivity by coating niobium diselenide onto the surface of a gold film. Electrons inside the niobium diselenide material are transferred to the metal surface, thereby increasing the concentration of free electrons on the metal surface, improving the electric field strength at the sensing interface, and ultimately enhancing the sensitivity.

[0009] Furthermore, the transparent substrate is made of a cover glass, preferably BK7 glass. It serves as the coupling substrate for exciting surface plasmon resonance signals and is placed at the bottom layer.

[0010] Furthermore, the gold film has a thickness of 45 nm, which is used to excite surface plasmon resonance.

[0011] Furthermore, the niobium diselenide sensitive coating has six layers, each with a thickness of 0.9 nm. Niobium diselenide is dispersed in a solvent, with a small amount of polymethyl methacrylate (PMMA) added, and then cured onto the surface of the gold film through spin coating and drying steps. The amount of PMMA added to the niobium diselenide dispersion is 0.1 g / L. The role of adding PMMA is adhesion, adhering the niobium diselenide to the gold film.

[0012] The second objective of this invention is to provide a method for preparing a highly sensitive sensing film based on niobium diselenide layered material, comprising the following steps: depositing a gold film on a transparent substrate, and then coating a niobium diselenide sensitive coating on top of the gold film to form a niobium diselenide sensitive coating, thereby obtaining a highly sensitive sensing film based on niobium diselenide layered material.

[0013] Furthermore, the preparation method specifically includes the following steps: (1) Clean the transparent substrate, dry it with nitrogen, and then place it in a vacuum chamber for ion bombardment; (2) A chromium target is first deposited on the transparent substrate that has been pretreated in step (1) as a transition layer, and then a gold target is deposited to obtain a gold film; (3) Niobium diselenide is dispersed in an organic solvent to obtain a niobium diselenide dispersion, then polymethyl methacrylate is added, and the resulting mixture is coated on a substrate containing a gold film to form a niobium diselenide sensitive coating. After drying, a highly sensitive sensing film based on niobium diselenide layered material is obtained.

[0014] Furthermore, the specific steps of ion bombardment in step (1) include: evacuating the vacuum chamber to a vacuum level of 6 × 10⁻⁶. -3 After Pa, apply a negative bias voltage of 200-500V for ion bombardment for 5-10 minutes to remove the surface oxide layer.

[0015] Furthermore, the deposition process of the transition layer in step (2) specifically includes the following steps: first, start the mechanical pump for rough pumping to 10... -2 Pa, then restart the molecular pump to evacuate to a background vacuum of ≤5×10⁻⁶. -4 Pa; electron beam current is 80-100mA, accelerating voltage is 6-8kV, deposition rate is 0.2-0.5Å / s, substrate stage rotation speed is 5-10rpm, and 2nm transition layer is formed by evaporating chromium target.

[0016] Furthermore, the gold film deposition process described in step (2) specifically includes the following steps: stabilizing the vacuum degree at 5 × 10⁻⁶. -4Below Pa, electron beam evaporation of gold target material (purity ≥99.99%) was initiated at a deposition rate of 1.0-1.5 Å / s and a total deposition time of 8-12 minutes. The material was kept under vacuum and cooled to below 80°C. The high valve was closed, nitrogen gas was introduced to atmospheric pressure, and the sample was removed to obtain a gold film with a thickness of 45 nm.

[0017] Further, the organic solvent mentioned in step (3) is chloroform; and / or, The concentration of the niobium diselenide dispersion is 0.2 mg / mL.

[0018] Further, the coating process of the niobium diselenide sensitive coating in step (3) specifically includes the following steps: the mixture is drop-coated onto the sample obtained in step (2), spread at a low speed of 500 rpm for 10 seconds, then formed into a film at a high speed of 1500-3000 rpm for 30-60 seconds, dried, and the residual solvent is removed to obtain the niobium diselenide sensitive coating.

[0019] The third objective of this invention is to provide an application of a highly sensitive sensing film based on niobium diselenide layered material in the field of optical devices.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects: This invention provides a novel surface plasmon resonance sensing film based on NbSe2 nanomaterials, comprising: a transparent substrate, a gold film, and a niobium diselenide sensitive coating. The transparent substrate is a cover glass, which, due to its low refractive index, can effectively serve as a coupling substrate, promoting total internal reflection and coupled resonance, which is crucial for the excitation of surface plasmons and the generation of sensing signals. The gold film has a thickness of 45 nm, enabling efficient excitation of surface plasmon waves. The niobium diselenide sensitive coating is obtained by spin-coating and drying NbSe2 nanosheets doped with a small amount of PMMA, serving as a waveguide layer in the sensing structure to enhance sensing sensitivity. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the process for preparing the highly sensitive sensing membrane according to the present invention; Figure 2 The result of detecting trace amounts of glucose using the highly sensitive sensing membrane prepared in Example 1 is shown in the figure. Figure 3 The simulation results are shown in the figure for the number of niobium diselenide sensitive coating layers and the electric field strength at the sensing interface. Figure 4 A comparison of the sensitivity of a traditional gold thin-film sensing structure and a sensing structure coated with niobium diselenide. Figure 5 The graph shows the quantitative detection results of glucose solutions of different concentrations using the highly sensitive sensing membrane prepared in Example 1. Figure 6 The real-time detection response of the highly sensitive sensing membrane prepared in Example 1 to glucose solutions of different concentrations is shown in the figure. Figure 7 A comparison of the sensitivity of high-sensitivity sensing films under different two-dimensional materials; Figure 8 The diagram shows the structural optimization of gold films of different thicknesses and niobium diselenide sensitive coating layers with different numbers of layers. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] This invention provides a method for preparing a highly sensitive sensing film based on niobium diselenide layered material, comprising the following steps: depositing a gold film on a transparent substrate, and then coating a niobium diselenide sensitive coating on top of the gold film to form a niobium diselenide sensitive coating, thereby obtaining a highly sensitive sensing film based on niobium diselenide layered material.

[0028] In some embodiments of the present invention, the preparation method specifically includes the following steps: (1) Clean the transparent substrate, dry it with nitrogen, and then place it in a vacuum chamber for ion bombardment; (2) A chromium target is first deposited on the transparent substrate that has been pretreated in step (1) as a transition layer, and then a gold target is deposited to obtain a gold film; (3) Niobium diselenide is dispersed in an organic solvent to obtain a niobium diselenide dispersion, then polymethyl methacrylate is added, and the resulting mixture is coated on a substrate containing a gold film to form a niobium diselenide sensitive coating. After drying, a highly sensitive sensing film based on niobium diselenide layered material is obtained.

[0029] In some embodiments of the present invention, the specific steps of ion bombardment in step (1) include: evacuating the vacuum chamber to a vacuum level of 6 × 10⁻⁶. -3 After Pa, apply a negative bias voltage of 200-500V for ion bombardment for 5-10 minutes to remove the surface oxide layer.

[0030] In some embodiments of the present invention, the deposition process of the transition layer in step (2) specifically includes the following steps: first, start the mechanical pump for rough pumping to 10. -2 Pa, then restart the molecular pump to evacuate to a background vacuum of ≤5×10⁻⁶. -4 Pa; electron beam current is 80-100mA, accelerating voltage is 6-8kV, deposition rate is 0.2-0.5Å / s, substrate stage rotation speed is 5-10rpm, and 2nm transition layer is formed by evaporating chromium target.

[0031] In some embodiments of the present invention, the gold film deposition process in step (2) specifically includes the following steps: stabilizing the vacuum degree at 5 × 10⁻⁶. -4 Below Pa, electron beam evaporation of gold target material (purity ≥99.99%) was initiated at a deposition rate of 1.0-1.5 Å / s and a total deposition time of 8-12 minutes. The material was kept under vacuum and cooled to below 80°C. The high valve was closed, nitrogen gas was introduced to atmospheric pressure, and the sample was removed to obtain a gold film with a thickness of 45 nm.

[0032] In some embodiments of the present invention, the organic solvent in step (3) is chloroform.

[0033] In some embodiments of the present invention, the concentration of the niobium diselenide dispersion is 0.2 mg / mL.

[0034] In some embodiments of the present invention, the concentration of polymethyl methacrylate in the niobium diselenide dispersion is 0.1 g / L.

[0035] In some embodiments of the present invention, the coating process of the niobium diselenide sensitive coating in step (3) specifically includes the following steps: the mixture is drop-coated onto the sample obtained in step (2), spread at a low speed of 500 rpm for 10 seconds, and then formed into a film at a high speed of 1500-3000 rpm for 30-60 seconds, dried, and the residual solvent is removed to obtain the niobium diselenide sensitive coating.

[0036] The niobium diselenide sensitive material in step (3) of this invention is prepared by liquid phase exfoliation. The specific steps are as follows: Niobium diselenide bulk material (purity ≥99.9%) is initially crushed into micron-sized particles (particle size ≤50μm) by mechanical grinding to obtain NbSe2 powder; NbSe2 powder is mixed with N-methylpyrrolidone (NMP) solution, and the concentration is controlled at 1-5mg / mL (NMP can enhance the wettability of NbSe2, and controlling the solution concentration can avoid excessive concentration leading to agglomeration). Then the mixture is placed in an ice bath sonicator and treated at 200-400W for 4-12 hours. After sonication, it is allowed to stand for 1 hour to allow the large particles that have not been exfoliated to settle; low-speed centrifugation (500-1000rpm, 10 minutes) is used to remove the unexfoliated bulk particles; high-speed centrifugation (8000-12000rpm, 30 minutes) is used to collect the monolayer / few-layer NbSe2 nanosheets in the upper dispersion, which is the niobium diselenide sensitive material.

[0037] For example, in the following embodiments of the present invention, the method for preparing the highly sensitive sensing film based on niobium diselenide layered material includes the following steps: (1) Pretreatment of the substrate: The coverslip was ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes each to remove organic contaminants from the surface of the coverslip; after drying with nitrogen, it was placed in an oven at 120℃ for 30 minutes, and then the coverslip was placed in a vacuum chamber and evacuated to 6×10 -3 After Pa, apply a negative bias voltage of 200-500V (preferably 200V) for ion bombardment for 5-10 minutes (preferably 10 minutes) to remove the surface oxide layer; (2) Deposition of gold film: A gold target (purity ≥ 99.99%) is installed in the electron beam evaporation coating machine, and a chromium target is used as a transition layer. The position of the electron gun is adjusted so that the electron beam is focused on the central area of ​​the target. The mechanical pump is first turned on to roughly pump to 10. -2 Pa, then restart the molecular pump to evacuate to a background vacuum of ≤5×10⁻⁶. -4 Pa (preferably 5 × 10) -4Pa); The electron beam current is set to 80-100mA (preferably 100mA), the accelerating voltage is 6-8kV (preferably 8kV), the film thickness is monitored in real time by a quartz crystal microbalance, the deposition rate is 0.2-0.5Å / s (preferably 0.5Å / s), and the substrate stage rotation speed is 5-10rpm (preferably 10rpm) to ensure deposition uniformity, and the chromium target is evaporated to form a 2nm transition layer; Waiting for the vacuum level to stabilize at 5×10 -4 Pa or less (preferably 5×10) -4 (Pa) The electron beam evaporation of the gold target (purity ≥99.99%) is initiated. The deposition rate is adjusted to 1.0-1.5 Å / s (preferably 1.5 Å / s) through the film thickness monitoring system. The total deposition time is 8-12 minutes (preferably 10 minutes). The film is kept under vacuum and cooled to below 80°C (preferably 30°C) to prevent thermal stress cracking of the film. The high pressure valve is closed, nitrogen is introduced to atmospheric pressure, and the sample is taken out to obtain a gold film with a thickness of 45 nm, which is used to excite surface plasmon resonance. (3) Preparation of niobium diselenide sensitive material: High-purity niobium diselenide bulk material (purity ≥ 99.9%) is selected and initially crushed into micron-sized particles (particle size ≤ 50 μm) by mechanical grinding to obtain NbSe2 powder; the NbSe2 powder is dispersed in NMP solution, and the concentration is controlled at 1-5 mg / mL (preferably 1 mg / mL) to avoid excessive concentration leading to agglomeration; after mixing NbSe2 powder with NMP solution, it is placed in an ice bath ultrasonic instrument for 4-12 hours (preferably 4 hours) (power 200). -400W, preferably 200W, pulse mode on / off cycle 2:1), utilize cavitation effect to disrupt interlayer van der Waals forces; after sonication, let stand for 1 hour to allow unpeeled large particles to settle; low-speed centrifugation (500-1000rpm, preferably 1000rpm, 10 minutes) removes unpeeled bulk particles; high-speed centrifugation (8000-12000rpm, preferably 12000rpm, 30 minutes) collects monolayer / few-layer NbSe2 nanosheets, i.e., niobium diselenide sensitive material, from the upper dispersion; (4) Deposition of niobium diselenide sensitive coating: The niobium diselenide sensitive material obtained in step (3) is dispersed in chloroform solvent to obtain a niobium diselenide dispersion with a concentration of 0.2 mg / mL. Then, a small amount of PMMA (concentration 0.1 g / L) is added to obtain a mixture. The mixture is dropped onto the center of the gold film and the spin coater is started immediately. Spread at low speed (500 rpm, 10 seconds) to ensure that the solution uniformly covers the substrate. Form the film at high speed (1500-3000 rpm, preferably 3000 rpm, 30-60 seconds). The film thickness is controlled by centrifugal force. After spin coating, the sample is placed on a hot plate at 80-100℃ (preferably 80℃) for 5-10 minutes (preferably 10 minutes) to remove residual solvent and obtain a niobium diselenide sensitive coating with a thickness of 0.9 nm.

[0038] The niobium diselenide sensitive coating described in step (3) can be repeatedly coated, and the number of coating layers can be 1-6 layers, such as 1 layer, 2 layers, 3 layers, 4 layers, 5 layers or 6 layers, preferably 6 layers.

[0039] Using the above preparation method, a highly sensitive sensing film based on niobium diselenide layered material can be prepared, which includes, from bottom to top: a transparent substrate, a gold film, and a niobium diselenide sensitive coating.

[0040] The transparent substrate is made of cover glass, preferably BK7 glass. It serves as the coupling substrate for exciting surface plasmon resonance signals and is placed at the bottom layer.

[0041] The gold film has a thickness of 45 nm and is used to excite surface plasmon resonance.

[0042] The niobium diselenide sensitive coating has 1-6 layers, and each layer has a thickness of 0.9 nm.

[0043] All raw materials used in this invention were purchased from the market.

[0044] The technical solution of the present invention will be further illustrated by the following embodiments.

[0045] Figure 1 This is a schematic diagram of the process for preparing the highly sensitive sensing membrane according to the present invention.

[0046] Example 1 A method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material includes the following steps: (1) Pretreatment of the substrate: The coverslip was ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes each to remove organic contaminants from the surface of the coverslip; after drying with nitrogen, it was placed in an oven at 120℃ for 30 minutes, and then the coverslip was placed in a vacuum chamber and evacuated to 6×10 -3 After Pa, a negative bias voltage of 200V is applied for ion bombardment for 10 minutes to remove the surface oxide layer. (2) Deposition of gold film: A gold target (purity ≥ 99.99%) is installed in the electron beam evaporation coating machine, and a chromium target is used as a transition layer. The position of the electron gun is adjusted so that the electron beam is focused on the central area of ​​the target. The mechanical pump is first turned on to roughly pump to 10. -2 Pa, then restart the molecular pump to evacuate to a background vacuum of 5 × 10⁻⁶ Pa. -4 Pa; The electron beam current was set to 100mA, the accelerating voltage to 8kV, the film thickness was monitored in real time using a quartz crystal microbalance, the deposition rate was 0.5Å / s, and the substrate stage rotation speed was 10rpm to ensure deposition uniformity. A 2nm transition layer was formed by evaporating the chromium target. Waiting for the vacuum level to stabilize at 5×10-4 Pa, start electron beam evaporation of gold target material (purity ≥99.99%), adjust the deposition rate to 1.5 Å / s through film thickness monitoring system, the total deposition time is 10 minutes, maintain vacuum state and cool to 30℃ to prevent thermal stress cracking of film layer; close high valve, fill with nitrogen to atmospheric pressure and take out sample to obtain gold film with a thickness of 45 nm, which is used to excite surface plasmon resonance; (3) Preparation of niobium diselenide sensitive material: High-purity niobium diselenide bulk material (purity ≥99.9%) was selected and mechanically ground to break it into micron-sized particles (particle size 50μm) to obtain NbSe2 powder; NbSe2 powder was mixed with NMP solution, and the concentration was controlled at 1mg / mL. The resulting mixture was placed in an ice bath ultrasonic instrument for 4 hours (power 200W, pulse mode on / off cycle 2:1) to destroy the interlayer van der Waals forces by utilizing the cavitation effect; after ultrasonication, it was allowed to stand for 1 hour to allow the large particles that were not peeled to settle; low-speed centrifugation (1000rpm for 10 minutes) was used to remove the unpeeled bulk particles; high-speed centrifugation (12000rpm for 30 minutes) was used to collect the monolayer / few-layer NbSe2 nanosheets in the upper dispersion, which is the niobium diselenide sensitive material; (4) Deposition of niobium diselenide sensitive coating: The niobium diselenide sensitive material obtained in step (3) is dispersed in chloroform solvent to obtain a niobium diselenide dispersion with a concentration of 0.2 mg / mL. Then, a small amount of PMMA (concentration 0.1 g / L) is added to obtain a mixture. The mixture is dropped onto the center of the gold film surface and the spin coater is started immediately. Spread at low speed (500 rpm, 10 seconds) to ensure that the solution uniformly covers the substrate. Form a film at high speed (3000 rpm, 60 seconds) and control the film thickness by centrifugal force. After spin coating, the sample is placed on an 80℃ hot plate for pre-baking for 10 minutes to remove residual solvent and obtain a niobium diselenide sensitive coating with a thickness of 0.9 nm.

[0047] (5) Repeat step (4) 9 times to obtain a highly sensitive sensing film containing 6 layers of niobium diselenide sensitive coating (total thickness of 5.4 nm).

[0048] Performance testing: 1. Experimental Method: Figure 2 The results of using the surface plasmon resonance sensing structure prepared based on the high-sensitivity sensing film obtained in Example 1 for the detection of trace glucose solutions are presented in this invention. Figure 2 As can be seen, as the glucose concentration gradually increases from low concentration (0 ng / mL) to high concentration (5 ug / mL), the resonance angle in the SPR reflectance curve continues to shift towards higher angles, indicating that the sensor can stably respond to the refractive index change caused by glucose concentration, and the lowest detection limit reaches 1 ng / mL.

[0049] 2. This invention constructs an electromagnetic field simulation model containing a layered structure of niobium diselenide based on the transfer matrix method. It systematically explores the quantitative correlation between the electric field strength at the sensing interface and the number of layers in the niobium diselenide sensitive coating. The model is investigated for 0, 1, 2, 3, 4, 5, and 6 layers of the niobium diselenide sensitive coating. Specifically, using Comsol software, the layered structure of the SPR (BK7, chromium, gold film, niobium diselenide) is modeled and the electric field strength is calculated. The thicknesses between each layer are set to 1 μm, 2 nm, 45 nm, and N, respectively. 0.9 nm (in the niobium diselenide sensitive coating, each layer is 0.9 nm thick, and N represents the number of layers). Simulation results are as follows: Figure 3 As shown, Figure 3 The results show that as the number of niobium diselenide layers N increases from 0 to 6, the local electric field intensity at the interface between niobium diselenide and the transmission medium is significantly enhanced, and the maximum surface normalized electric field intensity shows a rapid growth trend. When the number of niobium diselenide sensing coating layers increases to 6, the electric field intensity at the sensing interface reaches its peak, which is about 4 times higher than that of the 0-layer structure. This change is attributed to the competition mechanism between interlayer coupling effect and electromagnetic field penetration depth: the niobium diselenide sensing coating can simultaneously optimize surface plasmon polariton (SPP) coupling efficiency and optical field localization.

[0050] 3. Compare traditional sensing structures based on single-layer gold films with sensing structures coated with NbSe2 nanolayers. For example... Figure 4 As shown, when L=0 (i.e., without the niobium diselenide sensitive coating), it represents a sensing structure with only a 45nm gold film, and its sensitivity is 131° / RIU (degrees per unit refractive index). When L=6, it represents a sensing structure with 6 layers of NbSe2 coated on the gold film surface, and its sensitivity is 270° / RIU (degrees per unit refractive index). Furthermore, as the number of NbSe2 layers increases, the angular sensitivity continuously improves, while the quality factor (FOM) remains at a high level, achieving a better balance between sensitivity and resonance quality under the 6-layer condition.

[0051] 4. Experimental methods: This experiment used glucose solutions of different concentrations (corresponding refractive indices of 1.3330, 1.3342, 1.3354, 1.3362, 1.3375, and 1.3386) to represent the analyte. As the refractive index of the analyte changed from 1.3330 to 1.3386, the composite sensing film was able to distinguish the corresponding change in refractive index. When the refractive index changed by approximately 0.0056, the change in the resonance angle was 1.58°, and the fitted angle sensitivity of this sensor was 286.38 degrees / refractive index, thus achieving quantitative detection of the analyte (see [link to relevant documentation]). Figure 5 ).

[0052] 5. Experimental methods: In this experiment, glucose solutions of different concentrations (corresponding refractive indices of 1.3330, 1.3342, 1.3354, 1.3362, 1.3375, and 1.3386, respectively) were used to represent analytes with different resonance signals. It was found that the sensing structure could rapidly and accurately measure the corresponding changes in glucose concentration, indicating that the sensing structure coated with six layers of NbSe2 nanomaterials prepared in Example 1 can achieve real-time detection of analytes (see [link to example]). Figure 6 ).

[0053] Comparative Example 1 Same as Example 1, except that NbSe2 is replaced with black phosphorus, graphene, molybdenum disulfide, niobium diselenide, molybdenum diselenide and tungsten diselenide, respectively.

[0054] Six layers of different two-dimensional material films of the same number and thickness were coated on top of the gold film. The corresponding angular sensitivity results are as follows. Figure 7 As shown, molybdenum disulfide has the lowest angular sensitivity at 73.94 degrees / refractive index, while niobium diselenide has the highest angular sensitivity at 270.35 degrees, which is 265% higher than that of molybdenum disulfide. This indicates that niobium diselenide has the best sensitization effect among two-dimensional materials.

[0055] Comparative Example 2 Same as Example 1, except that the thickness of the gold film is adjusted to 30nm, 35nm, 40nm, 45nm and 50nm respectively.

[0056] like Figure 8 As shown, after adjusting the gold film thickness to 30nm, 35nm, 40nm, 45nm and 50nm respectively, the corresponding angular sensitivity first increased and then decreased (to 135.71 degrees / refractive index, 220.16 degrees / refractive index, 245.56 degrees / refractive index, 270.35 degrees / refractive index, and 230.08 degrees / refractive index respectively). Therefore, 45nm was selected as the optimal gold film thickness for the sensor.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A highly sensitive sensing membrane based on niobium diselenide layered material, characterized in that, It comprises, from bottom to top, a transparent substrate, a gold film, and a niobium diselenide sensitive coating, wherein the niobium diselenide sensitive coating has 1-6 layers.

2. The high-sensitivity sensing membrane based on niobium diselenide layered material according to claim 1, characterized in that, The transparent substrate is made of a cover glass; and / or, The thickness of the gold film is 45 nm; and / or, The thickness of each layer of the niobium diselenide sensitive coating is 0.9 nm; and / or, The niobium diselenide sensitive coating has 6 layers.

3. A method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material as described in any one of claims 1-2, characterized in that, Includes the following steps: A gold film is deposited on a transparent substrate, and then a niobium diselenide sensitive coating is coated on top of the gold film to form a niobium diselenide sensitive coating, thus obtaining a highly sensitive sensing film based on niobium diselenide layered material.

4. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 3, characterized in that, The preparation method specifically includes the following steps: (1) Clean the transparent substrate, dry it with nitrogen, and then place it in a vacuum chamber for ion bombardment; (2) A chromium target is first deposited on the transparent substrate that has been pretreated in step (1) as a transition layer, and then a gold target is deposited to obtain a gold film; (3) Niobium diselenide is dispersed in an organic solvent to obtain a niobium diselenide dispersion, then polymethyl methacrylate is added, and the resulting mixture is coated on a substrate containing a gold film to form a niobium diselenide sensitive coating. After drying, a highly sensitive sensing film based on niobium diselenide layered material is obtained.

5. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 4, characterized in that, The specific steps of ion bombardment in step (1) include: evacuating the vacuum chamber to a vacuum level of 6 × 10⁻⁶. -3 After Pa, apply a negative bias voltage of 200-500V for ion bombardment for 5-10 minutes.

6. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 4, characterized in that, The deposition process of the transition layer in step (2) specifically includes the following steps: first, start the mechanical pump for rough pumping to 10. -2 Pa, then restart the molecular pump to evacuate to a background vacuum of ≤5×10⁻⁶. -4 Pa; electron beam current is 80-100mA, accelerating voltage is 6-8kV, deposition rate is 0.2-0.5Å / s, substrate stage rotation speed is 5-10rpm, and 2nm transition layer is formed by evaporating chromium target.

7. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 4, characterized in that, The gold film deposition process described in step (2) specifically includes the following steps: stabilizing the vacuum level at 5 × 10⁻⁶. -4 Below Pa, the electron beam evaporation of the gold target was initiated at a deposition rate of 1.0-1.5 Å / s and a total deposition time of 8-12 minutes. The sample was cooled to below 80°C while maintaining a vacuum state, the high valve was closed, nitrogen gas was introduced to atmospheric pressure, and the sample was removed to obtain a gold film with a thickness of 45 nm.

8. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 4, characterized in that, The organic solvent mentioned in step (3) is chloroform; and / or, The concentration of the niobium diselenide dispersion is 0.2 mg / mL.

9. The method for preparing a highly sensitive sensing membrane based on niobium diselenide layered material according to claim 4, characterized in that, The coating process of the niobium diselenide sensitive coating in step (3) specifically includes the following steps: the mixture is drop-coated onto the sample obtained in step (2), spread at a low speed of 500 rpm for 10 seconds, then formed into a film at a high speed of 1500-3000 rpm for 30-60 seconds, and dried to obtain the niobium diselenide sensitive coating.

10. The application of a highly sensitive sensing film based on niobium diselenide layered material as described in any one of claims 1-2 in the field of optical devices.

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