Molecularly imprinted micro-nano fiber interferometric plasticizer sensor, sensing method and manufacturing method

Abstract

The application discloses a kind of molecular imprinting micro-nano fiber interference type plasticizer sensor, sensing method and manufacturing method, and the sensor includes broadband light source, incident optical fiber, polydopamine molecular imprinting film layer coated micro-nano fiber cascade interferometer, outgoing optical fiber and spectrum analyzer;Broadband light source is connected with the left end of incident optical fiber, the right end center of incident optical fiber is connected with the left end of micro-nano fiber cascade interferometer, the right end of micro-nano fiber cascade interferometer is connected with the left end of outgoing optical fiber, and the right end of outgoing optical fiber is connected with spectrum analyzer;Micro-nano fiber cascade interferometer is used as the sensing probe for measuring plasticizer concentration.The plasticizer sensor of the application is simple to manufacture, compact structure, has greater advantage in sensitivity in the field of biochemical sensing, and different sensitivity refractive index sensors can be obtained by controlling the diameter of multi-core optical fiber.

Description

Technical Field

[0001] This invention belongs to the field of plasticizer sensor technology, specifically relating to a molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor, sensing method, and fabrication method. Background Technology

[0002] With the rapid development of the chemical industry, plasticizers are widely used in various fields to improve the quality of plastic products, such as food packaging and daily necessities. However, in practical applications, they are prone to leakage and integration into complex environments, making them difficult to detect. Therefore, requirements are placed on the detection sensitivity and recognition capabilities of sensors. In recent years, among various plasticizer detection schemes, fluorescence analysis, traditional GC, HPLC, GC-MS, near-infrared analysis, and Raman spectroscopy have achieved good detection and selective recognition effects. However, the fabrication of these sensors requires the use of large amounts of chemical solvents and numerous chemical reactions, inevitably leading to contamination of the sensor itself. Furthermore, result detection requires expensive analytical instruments, which are highly sensitive to environmental factors, making the overall scheme overly redundant and complex.

[0003] Molecular imprinting technology (MIT), also known as molecular template technology, is a technique that can construct specific recognition cavities on demand. Polydopamine, with its excellent properties of tunable surface chemistry, simple preparation conditions, and high affinity, is showing increasing potential in the field of surface molecular imprinting technology. By combining polydopamine with surface molecular imprinting technology, the advantages of both are combined, compensating for the impact of reaction liquid residues on the device during surface imprinting experiments, and greatly expanding the fine-grained control of the imprinted film preparation process, providing room for secondary modification or even more functional additions.

[0004] Micro- and nano-fiber devices, due to their subwavelength size, high sensitivity, and stability, are of great significance in studying the sensing mechanisms of composite materials under external stimuli. Micro- and nano-fiber cascaded interferometers are optical components based on micro- and nano-scale fiber fabrication technology. They can confine the light field to an extremely small region, enhancing the interaction between the light field and the external environment, thereby improving the sensitivity and selectivity of the sensor. Although micro- and nano-fiber cascaded interferometers offer intuitive signal output and high sensitivity, making them a good platform for sensing and detection methods, they cannot inherently identify plasticizers; therefore, further functional modifications are needed. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings and deficiencies of the prior art and to propose a molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor, sensing method, and fabrication method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor includes a broadband light source, an incident fiber, a micro / nano fiber optic cascaded interferometer coated with a polydopamine molecularly imprinted film, an outgoing fiber, and a spectrometer.

[0008] The broadband light source is connected to the left end of the incident fiber, the center of the right end of the incident fiber is connected to the left end of the micro-nano fiber cascaded interferometer, the right end of the micro-nano fiber cascaded interferometer is connected to the left end of the output fiber, and the right end of the output fiber is connected to the spectrometer.

[0009] Micro-nano fiber optic cascaded interferometers are used as sensing probes to measure plasticizer concentration.

[0010] The present invention also includes a sensing method based on the provided molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor, comprising the following steps:

[0011] The sensing area of ​​the molecularly imprinted micro / nano fiber optic cascaded interferometer sensor was placed in the plasticizer solution to be tested, and the interference spectrum in the spectrometer was recorded.

[0012] By comparing the wavelength shift of specific peaks in the interference spectrum, the corresponding concentration in the data is obtained, and thus the concentration of the plasticizer sample to be tested is determined.

[0013] The present invention also includes a method for fabricating a molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor, comprising the following steps:

[0014] High temperatures are provided by electric arc discharge to heat the optical fiber to a molten state, and motors at both ends run synchronously to draw micro-nano optical fibers.

[0015] A micro-nano fiber cascaded interferometer is fabricated by moving micro-nano fibers to the positions of electrodes using a motor and performing repeated discharges at each position.

[0016] Piranha solution and 20% APTES alcohol solution were modified on a micro-nano fiber cascaded interferometer, respectively.

[0017] The micro-nano fiber cascaded interferometer was immersed in a dopamine molecular imprinting polymerization solution to perform polydopamine molecular imprinting film coating.

[0018] The sensor device with the completed molecularly imprinted film coating is then subjected to template molecule elution.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] 1. The sensor of the present invention simply attaches and modifies the molecularly imprinted film layer onto the surface of the sensing functional area of ​​a micro-nano fiber optic cascaded interferometer during the processing by means of the self-polymerization behavior of dopamine in an alkaline environment. By utilizing the large evanescent field and high-sensitivity interference phenomenon of micro-nano fibers, combined with the specific recognition function and chemical environment stability of polydopamine molecular imprints, a highly sensitive sensor is obtained, which has great potential in the sensing and detection of plasticizers. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the sensor of the present invention;

[0022] Figure 2 This is a schematic diagram of a micro / nano fiber optic cascaded interferometer;

[0023] Figure 3 This is a schematic diagram of the polydopamine molecularly imprinted film layer after adhesion modification;

[0024] Figure 4 This is a flowchart of the sensor sensing method of the present invention;

[0025] Figure 5 This is a flowchart of the sensor manufacturing method of the present invention;

[0026] Figure 6 This is the spectral diagram corresponding to the sensor in the embodiment;

[0027] Figure 7 This is an interference spectrum drift diagram of the concentration change of plasticizer corresponding to the sensor in the embodiment;

[0028] Explanation of reference numerals: 1-Broadband light source; 2-Incident fiber; 3-Micro-nano fiber cascade interferometer; 4-Outgoing fiber; 5-Spectrometer; 131-Polydopamine molecularly imprinted film; 132-Sensing area of ​​micro-nano fiber cascade interferometer; 141-Clad layer of micro-nano fiber cascade interferometer; 142-Fiber core of micro-nano fiber cascade interferometer; 143-Polydopamine molecularly imprinted polymer film. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0030] Example

[0031] like Figure 1As shown, the present invention provides a molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor, comprising a broadband light source 1, an incident fiber 2, a micro / nano fiber optic cascaded interferometer 3 coated with a polydopamine molecularly imprinted film, an exiting fiber 4, and a spectrometer 5. The broadband light source is connected to the left end of the incident fiber, the center of the right end of the incident fiber is connected to the left end of the micro / nano fiber optic cascaded interferometer, the right end of the micro / nano fiber optic cascaded interferometer is connected to the left end of the exiting fiber, and the right end of the exiting fiber is connected to the spectrometer. The micro / nano fiber optic cascaded interferometer serves as a sensing probe for measuring the concentration of plasticizer.

[0032] like Figure 2 and Figure 3 As shown, the micro-nano fiber cascaded interferometer has a strong evanescent field, ultra-low bending loss, and a sophisticated structure. The micro-nano fiber cascaded interferometer is composed of three or more micro-nano fiber cones. The smooth surface of the sensing region 132 of the micro-nano fiber cascaded interferometer can serve as an attachment platform for the polydopamine molecularly imprinted film layer 131. The diameter of the uniform region of the micro-nano fiber cascaded interferometer is 6-15 μm, the diameter of the cone region is 4-12 μm, the period is 0.2-1 mm, and the overall length is 3-10 mm. The fiber core 142 of the micro-nano fiber cascaded interferometer is located at the center of the cladding 141 of the micro-nano fiber cascaded interferometer.

[0033] The polydopamine molecularly imprinted polymer film 143 is formed by combining with template molecules under alkaline conditions using the self-polymerization behavior of dopamine. In this embodiment, the thickness of the polydopamine molecularly imprinted polymer film is 30-100 nm. Due to its strong adhesion, it can be coated on the surface of a micro-nano fiber cascade interferometer.

[0034] The incident and output optical fibers are standard single-mode fibers with a core diameter of 8-10 μm (8 μm in this embodiment) and a cladding diameter of 125 μm. The incident fiber and the micro / nano fiber cascaded interferometer are connected without eccentricity, as are the micro / nano fiber cascaded interferometer and the output fiber. The connection method can be fusion splicing or other methods that connect the three fiber segments.

[0035] In this embodiment, the broadband light source has a center wavelength of 1550nm and a bandwidth of 400nm; the micro-nano fiber cascaded interferometer serves as a sensing probe with a length of 10mm.

[0036] During implementation, sensors can be customized according to the type of plasticizer, and have specific recognition functions and are stable over a long period of time.

[0037] The molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor operates by the following steps:

[0038] A broadband light source emits incident light waves, which excite the fundamental mode when transmitted through the incident optical fiber. When the light passes through the uniform sensing area of ​​the micro-nano fiber cascaded interferometer, the light in the fiber core of the micro-nano fiber cascaded interferometer leaks into the surrounding medium in the form of an evanescent field.

[0039] When the refractive index of the surrounding environment changes, the interference pattern will drift accordingly due to the dispersion effect. By observing the changes in the interference pattern, we can know the change in the concentration of plasticizer in the micro-nano fiber optic cascaded interferometer. The interference pattern can be observed in the spectrometer connected to the output fiber.

[0040] In addition, since molecular imprinting technology can be used in micro-nano fiber cascaded interferometers to construct specific recognition cavities as needed, this technology can memorize the three-dimensional structure and functional groups of the molecules being detected, and generate unique recognition cavities in the imprinted polymer film layer that resemble "keys and keychains", thereby enabling the specific recognition of plasticizers.

[0041] In another embodiment, a sensing method for the molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor described in the above embodiments is also provided, such as... Figure 4 As shown, it includes the following steps:

[0042] The sensing area of ​​the molecularly imprinted micro / nano fiber optic cascaded interferometer sensor was placed in the plasticizer solution to be tested, and the interference spectrum in the spectrometer was recorded.

[0043] By comparing the wavelength shift of specific peaks in the interference spectrum, the corresponding concentration in the data is obtained, and thus the concentration of the plasticizer sample to be tested is determined.

[0044] In another embodiment, a method for fabricating the molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor described in the above embodiments is also provided, such as... Figure 5 As shown, it includes the following steps:

[0045] High temperatures are provided by electric arc discharge to heat the optical fiber to a molten state, and motors at both ends run synchronously to draw micro-nano optical fibers.

[0046] A micro-nano fiber cascaded interferometer is fabricated by moving micro-nano fibers to the positions of electrodes using a motor and performing repeated discharges at each position.

[0047] Piranha solution and 20% APTES alcohol solution were modified on a micro-nano fiber cascaded interferometer, respectively.

[0048] The micro-nano fiber cascaded interferometer was immersed in a dopamine molecular imprinting polymerization solution to perform polydopamine molecular imprinting film coating.

[0049] The sensor device with the completed molecularly imprinted film coating is then subjected to template molecule elution.

[0050] In this embodiment, a specialized fiber optic fusion splicer is used to draw the micro / nano fiber. Then, by periodically moving the fiber along its axis and inducing arcs at each position using electrodes, multiple uniformly structured micro-fiber cone regions are formed on the micro / nano fiber, resulting in a cascaded micro / nano fiber interferometer with a diameter of 10.5 μm and a cone region period of 400 μm. When fabricating the cascaded micro / nano fiber interferometer using a commercially available specialized fiber optic fusion splicer, the left and right motors inside the splicer drive the fiber clamps, allowing the fiber to move freely along its axis between fixed electrodes and its movement speed controlled. The distance between the two electrode tips of the splicer is approximately 1 mm, and the width of the released arc region is approximately 240 μm. The intensity of the arc released by the electrode tips is controlled by the machine's control over the current supplied to the electrodes. The high temperature generated by the arc softens the silica fiber. The program then controls a single-sided motor to move the fiber at a uniform speed. Simultaneously, the heated and softened fiber is drawn into a low-loss micro / nano fiber free from intermodal interference. During the fabrication of micro / nano optical fibers, real-time observation can be achieved using the imaging system integrated into the special optical fiber fusion splicer. After the micro / nano optical fiber fabrication is complete, the fusion splicer motor drives the fiber back to its initial position. The resulting micro / nano optical fiber is approximately 6 mm in length, 10 μm in diameter, and has a taper diameter of approximately 6.5 μm.

[0051] In this embodiment, the micro / nano fiber cascaded interferometer was immersed in a piranha solution to slowly remove surface impurities and modify it with hydroxyl groups (-OH). Then, it was immersed in a 20% APTES solution with anhydrous ethanol as the solvent, where it reacted with the hydroxyl groups to form links, thus modifying it with amino groups. Next, the micro / nano fiber cascaded interferometer was immersed in a molecularly imprinted polymerization solution to polymerize a polydopamine molecularly imprinted film. Dopamine polymerization mainly involves a combination of non-covalent self-assembly and covalent polymerization mechanisms: First, dopamine undergoes an oxidation reaction to generate 5,6-dihydroxyindole (DHI). Next, DHI undergoes two reactions: First, DHI itself forms a covalent bond structure, linking with each other to form a stable and regular molecular chain structure; this polymerization is covalent oxidation polymerization. Second, DHI and two oxidized dopamine monomers form a (DA)2 / DHI complex trimer through physical self-assembly; this is a non-covalent self-assembly method. Both the covalent structure of DHI and the self-assembly of (DA)2 / DHI exist during the DA polymerization process. The resulting (DA)2 / DHI physical trimer is trapped in the oxidative polymerization product, leading to the deposition of a dark brown polydopamine precipitate. This process completes the film deposition and modification on the micro / nano fiber optic cascade interferometer, thus completing the sensor functionalization. Following this, an eluent (V...) is used... 乙醇 :V 浓氨水 :V 水The mixture (7:2:1) is eluted, and the template molecules on the polydopamine molecularly imprinted film are removed by physicochemical methods, leaving behind a three-dimensional recognition cavity with specific memory. When the plasticizer molecule being tested comes into contact again, it will be sensed and detected due to the recognition ability of the cavity site.

[0052] like Figure 2 The diagram shown is a schematic of a micro / nano fiber optic cascaded interferometer. Figure 3 The diagram shown is a schematic of the polydopamine molecularly imprinted film after adhesion modification.

[0053] like Figure 6 The image shows a comparison of the interference spectra of a micro / nano fiber optic cascaded interferometer with good spectral quality after the adhesion and elution experiments of a polydopamine molecularly imprinted film. After the molecularly imprinted film covers the fiber, the spectrum redshifts by 22.88 nm. After the template molecules are eluted, the spectrum blueshifts back by 6.08 nm, indicating that the sensor surface still maintains a good spectrum even after being covered by the molecularly imprinted film.

[0054] like Figure 7 As shown, this is a molecularly imprinted micro / nano fiber optic interferometric plasticizer sensor for detecting plasticizers at concentrations of 10... -19 M to 10 - 10 The response of the target concentration of dimethyl phthalate (DMP) in the detection solution between M and the concentration range of 10 -16 ~10 -11 M exhibits a logarithmic quasi-linear relationship. Software fitting results show that the sensor response sensitivity is 0.79865 nm / lg M, and the lowest detection limit is approximately 1.167 × 10⁻⁶. -16 M.

[0055] It should also be noted that, in this specification, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A molecularly imprinted micro-nano fiber interferometric plasticizer sensor, characterized in that, The application relates to a molecular imprinting micro-nano fiber cascade interferometer sensor for plasticizers. The broadband light source is connected with the left end of the incident fiber, the right end center of the incident fiber is connected with the left end of the micro-nano fiber cascade interferometer, the right end of the micro-nano fiber cascade interferometer is connected with the left end of the outgoing fiber, and the right end of the outgoing fiber is connected with the spectrum analyzer. The micro-nano fiber cascade interferometer is used as a sensing probe for measuring the concentration of plasticizers. The micro-nano fiber cascade interferometer is composed of three or more micro-nano fiber tapers, the uniform zone has a diameter of 6-15 mu m, the taper zone has a diameter of 4-12 mu m, the period size is 0.2-1 mm, the overall length is 3-10 mm, and the fiber core of the micro-nano fiber cascade interferometer is located at the most central position of the fiber. The thickness of the polydopamine molecular imprinting film layer is 30-100 nm. The polydopamine molecular imprinting film layer generates a recognition cavity, thereby realizing specific recognition of the plasticizer.

2. The molecularly imprinted micro-nano fiber interferometric plasticizer sensor according to claim 1, characterized in that, The incident fiber and the outgoing fiber are standard single-mode fibers, the single-mode fiber core has a diameter of 8-10 mu m, and the cladding has a diameter of 125 mu m. 3.The molecularly imprinted micro-nano fiber interferometric plasticizer sensor of claim 1, wherein, The incident fiber and the micro-nano fiber cascade interferometer are connected without eccentricity, and the micro-nano fiber cascade interferometer and the outgoing fiber are connected without eccentricity. 4.The molecularly imprinted micro-nano fiber interferometric plasticizer sensor of claim 1, wherein, The working steps of the molecular imprinting micro-nano fiber interferometric plasticizer sensor include the following steps. The broadband light source emits incident light waves, and the fundamental mode is excited when the incident light waves are transmitted in the incident fiber; when the light passes through the uniform sensing area of the micro-nano fiber cascade interferometer, the light in the fiber core of the micro-nano fiber cascade interferometer leaks to the surrounding medium in the form of an evanescent field; When the refractive index of the surrounding environment changes, the interference pattern will drift due to the dispersion effect, and the change of the concentration of the plasticizer outside the micro-nano fiber cascade interferometer can be known by observing the change of the interference pattern, and the interference pattern can be observed in the spectrum analyzer connected through the outgoing fiber.

5. A sensing method based on the molecularly imprinted micro-nano fiber interferometric plasticizer sensor according to claim 1, characterized in that, The steps include the following steps. The sensing area of the molecular imprinting micro-nano fiber cascade interferometer sensor is placed in the plasticizer solution to be measured, and the interference spectrum in the spectrum analyzer is recorded. The wavelength drift of the specific peak value of the interference spectrum is compared, the corresponding concentration in the data is obtained, and the concentration of the plasticizer sample to be measured is obtained.

6. The method for preparing the molecularly imprinted micro-nano fiber interferometric plasticizer sensor according to claim 1, characterized in that, The steps include the following steps. High temperature is provided through arc discharge, the fiber is heated to a molten state, and the two ends of the motor are synchronously operated to draw the micro-nano fiber; The micro-nano fiber is moved to the position of the electrode by the motor, and repeated discharge is performed at each position to prepare the micro-nano fiber cascade interferometer; The micro-nano fiber cascade interferometer is modified by piranha solution and 20% APTES content alcohol solution respectively; The micro-nano fiber cascade interferometer is immersed in a dopamine molecular imprinting polymerization solution to perform polydopamine molecular imprinting film layer polymerization coating; The sensor device with the completed molecular imprinting film layer coating is subjected to template molecule elution.

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