Trace lead ion concentration detection method based on TFBG-SPR integrated MXene film
By sputtering a gold film onto the surface of a tilted fiber Bragg grating and coating it with an MXene film, and combining this with a spectrometer, a highly sensitive and specific detection of lead ions was achieved, solving the problems of speed, accuracy, and cost in the detection of trace lead ions in existing technologies.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA JILIANG UNIV
- Filing Date
- 2026-03-20
- Publication Date
- 2026-04-28
AI Technical Summary
Existing technologies cannot quickly and accurately perform in-situ real-time detection of trace heavy metal ions such as lead ions, and traditional methods are costly and complex to operate.
A gold film was sputtered onto the surface of a tilted fiber Bragg grating and coated with an MXene film. Combined with a broadband light source, a polarization controller, and a spectrometer, the specific detection of lead ions was achieved through surface plasmon resonance.
It achieves a low detection limit (28.2 aM) and a fast response (about 2 minutes) for lead ions, and has the advantages of simple structure, low detection limit and fast response time, making it suitable for rapid and accurate detection in real-world environments.
Smart Images
Figure CN121933481A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fiber optic sensing technology, and specifically to a method for detecting lead ion concentration based on TFBG-SPR combined with MXene thin film. Background Technology
[0002] The non-biodegradable nature of heavy metal ions in nature means they are constantly exposed to humans through the food chain and polluted rainwater, seawater, and coal, thus causing a series of adverse effects on human health. Since heavy metals in nature, especially in aquatic environments, are often present in trace amounts and are colorless and odorless, they cannot be detected by smell or sight alone. Therefore, rapid and accurate detection of heavy metal ion concentrations in environmental aqueous solutions is essential.
[0003] Lead ions, a typical heavy metal ion, are widely used in building materials, oil refining, lead-acid batteries, paints, and other industries. Lead ions are difficult to decompose and easily combine with other toxic substances in water. If the concentration of lead ions in drinking water exceeds safe levels, it will cause serious damage to various organs of the human body.
[0004] Traditional analytical methods, such as cold vapor atomic absorption spectrometry (CVAAS), fluorescence spectrophotometry, inductively coupled plasma atomic emission spectrometry (ICPAES), and inductively coupled plasma mass spectrometry (ICP-MS), offer advantages in terms of high precision and sensitivity. However, these detection techniques are costly, time-consuming, and complex to operate. More importantly, they cannot perform in-situ real-time detection.
[0005] Currently, fiber optic sensors have shown great application potential in many fields such as biomedicine and chemical detection. Among them, the tilted fiber bragg grating (TFBG) is a special type of fiber grating in which the grating fringes are at a certain angle to the fiber normal. It is a special short-period fiber grating. Due to its unique structural characteristics, it has all the advantages of fiber bragg gratings and long-period fiber gratings. Through various structural designs, physical combinations and biochemical material modifications, TFBG can achieve high-precision detection of a variety of physical, mechanical, electromagnetic, biological, medical and chemical sensing quantities.
[0006] MXene is a novel two-dimensional transition metal carbide or nitride material. Its core advantages mainly stem from its high conductivity, large specific surface area, abundant surface functional groups, and tunable layered structure. MXene's enormous specific surface area provides numerous active sites for ion adsorption and catalytic reactions. By thermally depositing MXene on the surface of optical fibers, its layered structure provides adsorbable active sites for lead ions, enabling the sensor to respond to different concentrations of lead ions. This invention not only achieves the function of specific detection of lead ions but also features high sensitivity, strong specificity, and a low detection limit. Summary of the Invention
[0007] To address the shortcomings of existing technologies, this study developed a trace lead ion detection method based on tilted fiber Bragg grating plasmon resonance (TFBG-SPR) technology. Surface plasmon resonance is excited by sputtering a 50 nm thick gold film onto the surface of the tilted fiber Bragg grating, and then coating the gold film with an MXene functional film possessing specific recognition capabilities, thereby achieving specific detection of lead ions. The method includes the following steps: S1. Fabrication of tilted fiber grating (51) and sputtering of gold film (52); S2. Preparation and modification of MXene films (53) that can specifically bind to lead ions; Connection of S3, broadband light source (1), polarization controller (3), TFBG-SPR sensor (5), and spectrometer (6); S4. Detection of lead ion concentration, time response, and specificity.
[0008] In step S1, the optical fiber is etched using a phase mask method, and then a gold film of about 50 nm is deposited on the surface of the TFBG using magnetron sputtering.
[0009] In step S2, 1.0 g of Ti3AlC2 powder was added to 20 ml of dilute hydrofluoric acid solution in an oil bath at 60 °C, and magnetically stirred at 3500 rpm for 24 hours. After the reaction was completed, 40 ml of deionized water was added for dilution. After centrifugation at 3500 rpm for 5 minutes, the supernatant was aspirated with a dropper, and deionized water was added for repeated centrifugation until the pH of the supernatant was approximately 6. Then, N,N-dimethylamide solvent was added to the supernatant, and the mixture was sonicated in an ice bath for 2 hours to obtain an MXene colloidal solution. After vacuum filtration, a multilayer MXene solution with a concentration of 15.2 mg / mL was obtained. The optical fiber was immersed in the solution for 5 minutes and then removed and vacuum dried at 60 °C for more than 12 hours to obtain the optical fiber sensing element.
[0010] In step S2, the hydroxyl functional groups on the exposed Ti surface of MXene affect Pb. 2+It has specific adsorption properties for Pb 2+ The exchange of hydrogen bonds between the two hydroxyl groups allows Pb to... 2+ Two hydrogen bonds on Ti3C2(OH)2 are replaced to form Ti3C2(O2H)2. 2-2m Pb m ) structure. In this structure, Pb 2+ It is captured by the potential field formed by the surrounding hydroxyl groups and oxygen, forming a stable adsorption structure.
[0011] The Pb of the present invention 2+ The adsorption principle can be represented by the following reaction equation:
[0012] Preferably, the MXene has a multi-layer structure.
[0013] In step S3, the broadband light source (1), polarization controller (3), TFBG-SPR sensor (5), and spectrometer (6) are connected as follows: the broadband light source (1) is connected to the left end of the polarization controller (3) through a single-mode fiber (2), the polarization controller (3) is connected to the TFBG-SPR sensor (5), the TFBG-SPR sensor (5) is fixed in the flow cell (4), and the right end is connected to the spectrometer (6); the broadband light source (1) is used to provide the light source, the polarization controller (3) is used to adjust the P-state polarization, the flow cell (4) is used to add the lead ion solution to be tested, and the spectrometer (6) is used to monitor and record the spectral changes; when the MXene film (53) modified on the surface of TFBG-SPR (5) combines with lead ions, the refractive index changes, which is manifested as a shift in the transmission spectrum on the spectrometer (6). By comparing the relationship between different lead ion concentrations and the transmission spectrum shift, the concentration of lead ions can be detected.
[0014] Preferably, the wavelength of the broadband light source (1) is 1420-1620 nm.
[0015] In step S4, the modulation concentration for lead ion concentration detection is: 100aM, 1fM, 10fM, 100fM, 1pM, 10pM, 100pM, 1nM.
[0016] The time response detection in step S4 takes approximately 2 minutes.
[0017] The cation included in the specific detection in step S4 is: Pb 2+ K + Cu 2+ Fe 3+ Mg 2+ Na + .
[0018] The working principle of the trace lead ion concentration detection method based on TFBG-SPR integrated MXene thin film of this invention is as follows: When light waves enter the optical fiber and are completely reflected by the fiber sidewalls, the tilted fiber grating can also excite evanescent surface plasmon resonance waves on the gold surface. When the p-polarized component of the light enters the gold film, the free electrons of the gold film interact with the p-polarized component of the light to generate plasma. At the interface between the optical fiber and the gold film, plasma vibration forms surface plasmon waves. When the horizontal component of the evanescent wave vector matches the wave vector of the surface plasmon wave and energy transfer occurs, the evanescent wave and the surface plasmon wave resonate, generating surface plasmon resonance. Light energy near the resonance wavelength is absorbed, resulting in a resonance valley in the output spectrum. The MXene thin film on the surface of the tilted fiber grating absorbs lead ions from the test solution, causing a change in the local refractive index, and the resonance valley and resonance wavelength also change. Therefore, the lead ion concentration can be inferred by monitoring the shift of the resonance wavelength.
[0019] In summary, this invention provides a method for specifically detecting lead ion concentration. This method is based on the specific adsorption of lead ions by an MXene thin film, which alters the effective refractive index, causing a shift in the transmission spectrum and enabling the detection of lead ions. It has advantages such as simple structure, low detection limit, and fast response time.
[0020] The beneficial effects of this invention are: This invention combines the specific adsorption capacity of MXene thin films for lead ions with the in-situ high-sensitivity detection capability of TFBG. The sensor has a detection limit for lead ions as low as 28.2 aM and a response time of approximately 2 minutes. It can be applied to provide rapid and accurate response to lead ions in real-world environments, demonstrating strong innovation and practical value, and showing promising application prospects. Attached Figure Description
[0021] Figure 1 A schematic diagram of a lead ion concentration detection method based on TFBG-SPR.
[0022] Figure 2 The transmission spectra and fitting curves of transmission peak intensity changes in lead ion solutions of different concentrations are shown in the figure.
[0023] Figure 3 Time response diagram of lead ion detection based on TFBG-SPR.
[0024] Figure 4 Comparison of specific responses of lead ion detection based on TFBG-SPR at wavelengths of 1513.8 nm and 1517.9 nm. Specific implementation methods
[0025] The present invention will be further described in detail below with reference to specific embodiments: Example 1: Fabrication of tilted fiber Bragg grating and sputtering of gold film.
[0026] In this embodiment, the preparation steps of the TFBG-SPR sensor (5) are as follows: First, the photosensitive fiber is subjected to hydrogen loading treatment, and after ultraviolet writing and annealing, a tilted fiber grating (51) with a tilt angle of 8° is obtained; then the tilted fiber grating (51) is placed in the magnetron sputtering deposition cavity, and a gold film (52) with a thickness of about 50 nm is deposited on its surface.
[0027] Example 2: Preparation and modification of MXene films that can specifically bind to lead ions.
[0028] In this embodiment, the preparation and modification of the MXene film (53) that can specifically bind to lead ions are specifically carried out as follows: In an oil bath at 60 °C, 1.0 g of Ti3AlC2 powder was added to 20 ml of dilute hydrofluoric acid solution and magnetically stirred at 3500 rpm for 24 hours. After the reaction was completed, 40 ml of deionized water was added for dilution. After centrifugation at 3500 rpm for 5 minutes, the supernatant was aspirated with a dropper, and deionized water was added for repeated centrifugation until the pH of the supernatant was approximately 6. Then, N,N-dimethylamide solvent was added to the supernatant and sonicated in an ice bath for 2 hours to obtain an MXene colloidal solution. The MXene colloidal solution was refrigerated and stored in the range of 2 °C–6 °C.
[0029] After vacuum filtration, a multilayer MXene solution with a concentration of 15.2 mg / mL was obtained from the MXene colloid.
[0030] Rinse the gold-plated TFBG with deionized water to remove impurities from the surface of the sensor after gold plating, repeating 2-3 times.
[0031] The thoroughly cleaned gold-plated TFBG was placed in a prepared multilayer MXene solution with a concentration of 15.2 mg / mL for 5 minutes to allow the multilayer MXene to adhere to the surface of the gold-plated TFBG. After removal, it was vacuum dried at 60°C for 12 hours to obtain the TFBG-SPR sensor with integrated MXene (5), which was then stored in a vacuum environment.
[0032] Example 3: Construction of the detection platform.
[0033] In this embodiment, see Figure 1The detection platform is a single-mode optical fiber (2) connecting a broadband light source (1), a polarization controller (3), a TFBG-SPR sensor (5) placed in a flow cell (4), and a spectrometer (6). The broadband light source (1) has a wavelength range of 1420-1620 nm and is used to provide light. The polarization controller (3) is used to adjust the P-state polarization. The flow cell (4) is used to add the lead ion solution to be tested. The spectrometer (6) is used to monitor and record the spectral changes. When the MXene film (53) modified on the surface of the TFBG-SPR sensor binds lead ions, the refractive index changes, which is reflected in the drift of the transmission spectrum on the spectrometer (6). By comparing the relationship between different lead ion concentrations and the transmission spectrum drift, the concentration of lead ions can be detected.
[0034] Example 4: Detection of lead ion concentration, time response, and specificity.
[0035] All solutions used for lead ion concentration detection, time response detection, and specificity detection were prepared using deionized water.
[0036] Lead ion concentration detection: The MXene-modified TFBG-SPR sensor was rinsed with deionized water and placed in a flow cell (4). Lead ion solutions of different concentrations were prepared using deionized water, with concentrations of 100 aM, 1 fM, 10 fM, 100 fM, 1 pM, 10 pM, 100 pM, and 1 nM. Deionized water was added to the flow cell (4), and the initial P-state spectrum was recorded using a spectrometer (6). Then, lead ion solutions were added to the flow cell (4) and allowed to stand. The transmission spectrum was then recorded using the spectrometer (6). Different concentrations of lead ion solutions were added sequentially, and the above steps were repeated to obtain the transmission spectra of lead ion solutions of different concentrations. Fitting curves were then plotted, as shown in the figure. Figure 2 As shown.
[0037] Time response detection: Deionized water was added to the flow cell (4), and the initial spectrum was recorded using a spectrometer (6). Subsequently, a 100 aM lead ion solution was added to the flow cell (4), and the spectrum was continuously detected and recorded for 210 seconds using a spectrometer (6). The change in the transmission spectral intensity of the 100 aM lead ion solution over time was obtained, as shown in the figure. Figure 3 As shown.
[0038] Specific detection: Pb cations with a concentration of 1 nM were prepared respectively. 2+ K + Cu 2+ Fe 3+ Mg 2+ Na +The test solution. First, the transmission spectrum of the TFBG-SPR sensor with integrated Mxene film in deionized water was detected. Then, a test solution was added to the flow cell and allowed to stand. Subsequently, the transmission spectrum was recorded using a spectrometer (6). The solution was then rinsed multiple times with deionized water. Different test solutions were added in sequence, and the above steps were repeated to evaluate the specificity of the detection method for different ions, such as Figure 4 As shown.
[0039] The embodiments described above provide a detailed explanation of the technical solution of the present invention, but the scope of protection of this disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of the present invention.
Claims
1. A method for detecting trace lead ion concentration based on TFBG-SPR integrated MXene thin film, wherein the detection device comprises a broadband light source (1), a single-mode optical fiber (2), a polarization controller (3), a flow cell (4), a TFBG-SPR sensor (5), and a spectrometer (6); characterized in that: The broadband light source (1) is connected to the input end of the polarization controller (3) through a single-mode optical fiber (2); the output end of the polarization controller (3) is connected to the left end of the TFBG-SPR sensor (5), and the right end of the TFBG-SPR sensor (5) is connected to the spectrometer (6). The fabrication steps of the TFBG-SPR sensor (5) are as follows: First, hydrogen is loaded onto the photosensitive fiber and then ultraviolet etching and annealing are performed to form a tilted fiber grating (51) with a tilt angle of 8°. Then, the tilted fiber grating (51) is placed in a magnetron sputtering deposition chamber to deposit a gold film (52) with a thickness range of 50 nm on its surface. Finally, an MXene film (53) is deposited on the gold film. The detection steps of the trace lead ion concentration detection method based on TFBG-SPR integrated MXene film are as follows: First, fix the TFBG-SPR sensor (5) in the flow cell (4); then add the lead ion test solution to the flow cell (4), and the lead ions combine with the MXene film on the surface of the TFBG-SPR sensor (5) to achieve lead ion adsorption; the light emitted by the broadband light source (1) passes through the TFBG-SPR sensor (5) and is displayed on the spectrometer (6); finally, add lead ion solutions of different concentrations to the flow cell (4) and fit the data recorded on the spectrometer (6) to obtain the relationship between different lead ion concentrations and transmission spectrum drift, so as to realize the concentration detection of lead ions; The fabrication steps of the TFBG-SPR sensor (5) with integrated MXene thin film are as follows: Step 1: In an oil bath at 60 °C, add 1.0 g Ti3AlC2 powder to 20 ml dilute hydrofluoric acid solution and stir magnetically at 3500 rpm for 24 hours. After the reaction is complete, add 40 ml deionized water for dilution. After centrifugation at 3500 rpm for 5 minutes, aspirate the supernatant with a dropper, add deionized water, and repeat centrifugation until the pH of the supernatant is approximately 6. Then, add N,N-dimethylamide solvent to the supernatant and sonicate in an ice bath for 2 hours to obtain an MXene colloidal solution. After sonication, the MXene colloidal solution is refrigerated and stored in the range of 2 °C–6 °C. Step 2: After vacuum filtration, the MXene colloid was obtained as a multilayer MXene solution with a concentration of 15.2 mg / mL; Step 3: Rinse the gold-plated TFBG with deionized water to remove impurities from the surface of the sensor after gold plating. Repeat 2-3 times. Step 4: Place the thoroughly cleaned gold-plated TFBG into the multilayer MXene solution with a concentration of 15.2 mg / mL prepared in Step 2 for 5 minutes to allow the multilayer MXene to adhere to the surface of the gold-plated TFBG. After removal, vacuum dry at 60°C for 12 hours to obtain the TFBG-SPR sensor (5) with integrated MXene, and then store it in a vacuum environment.