Integrated optical fiber biosensor for microdialysis sampling and fast separation and method of manufacture

Abstract

The present invention discloses an integrated fiber optic biosensor for microdialysis sampling and rapid separation, and its preparation method. The sensor comprises a broadband light source, a transmission optical path, a circulator, a demodulator, a dialysis membrane, a microdialysis channel, an optofluidic electrophoresis channel, an inlet, an outlet, a microinjection pump, and an electrophoresis apparatus. The preparation method includes the following steps: drawing a microstructured optical fiber with a dual-channel structure and two fiber cores; constructing a microdialysis microfluidic circuit and integrating the dialysis membrane within the optical fiber; opening holes perpendicular to the optical fiber in the microdialysis channel and the optofluidic electrophoresis channel to enable the circulation of dialysate and the encapsulation of microelectrodes; fabricating a dual FBG structure within the two fiber cores; and finally coupling the optical fibers to form a closed optical path. This invention addresses the bottleneck problem of existing fiber optic biosensors that rely on off-fiber sample pretreatment, enabling the integrated collection, separation, and detection of complex samples from living tissues, blood vessels, and other locations, thereby promoting the medical application of fiber optic in vivo / online biosensors.

Description

Technical Field

[0001] The present invention relates to an integrated optical fiber biosensor for microdialysis sampling and rapid separation and a preparation method thereof, belonging to the technical field of optical fiber sensing. Background Art

[0002] As technology trends toward intelligent development, fiber optic sensors have demonstrated unique advantages in many fields. Recent advances and intersections in micro- and nanotechnology, materials technology, and biotechnology have enabled the emergence of new methods and approaches for fiber optic sensing. Fiber optic biosensors, in particular, have demonstrated irreplaceable advantages in numerous applications and have garnered significant attention. Their integrated structure and minimal invasiveness make them suitable for harsh working environments and remote transmission, offering significant application value in fields such as medicine and biology.

[0003] In recent years, fiber optic biosensors have shown a multi-field cross-development trend. The types of sensing units generally include the following categories: (1) surface plasmon resonance fiber optic sensors. Samples do not need to be labeled and the dynamic process of the reaction can be monitored in real time; (2) evanescent field sensors. The analyte can be detected by analyzing the light intensity; (3) fiber Bragg grating and long-period fiber grating sensors, which use the wavelength offset to measure the change in the concentration of external biomolecules; (4) fiber interferometric biosensors. Sample detection is achieved by shifting the interference wavelength. Based on the above types, it is also possible to measure a wide range of substances including neurotransmitters, antibiotics, amino acids, pathogenic microorganisms, human IgG and IgM, bovine hemoglobin and bovine serum albumin, red blood cells and T lymphocytes and granulocytes, serum HIV-specific antibodies, staphylococci, enterotoxins, insulin, alpha-fetoprotein and Japanese schistosomiasis antibodies. It can be seen that fiber optic biosensors have broad application prospects in the fields of biology and medicine.

[0004] Current fiber optic sensors are still basically oriented towards the principle detection of single components. As we all know, in practical applications in the fields of medicine, biology, and pharmaceuticals, the detection objects are generally mixed samples of multiple components. For the actual test objects, various means such as chromatography, filtration, and centrifugation need to be used to separate and process the mixed substances before detection, but the current sensor devices themselves basically do not include any pre-injection processing functions. The above problems not only complicate the system structure, but also increase the volume burden of the instrument, making it difficult to give full play to the advantages of fiber optic sensors in trace and online sensing, and restricting the integration, miniaturization and stabilization of fiber optic sensing systems. Therefore, the extraction and separation process of trace samples (especially mixed samples) is very important in the entire trace analysis process, which will determine whether the fiber optic online trace analysis process has practical application value. Summary of the Invention

[0005] The application aims to provide a microdialysis sampling and rapid separation integrated optical fiber biosensor and a preparation method.

[0006] The application is achieved as follows:

[0007] The application is achieved as follows:

[0008] Further, the outer diameter of the double-channel double-core optical fiber is about 500 μm, the distance between the first core and the second core should be the shortest to ensure that the two cores can be exposed at the same time during the double-FBG etching, and at the same time, the mode coupling between the first core and the second core should be avoided.

[0009] Further, the positions of the sample inlet and the sample outlet are perpendicular to the surface of the double-channel double-core optical fiber, and are respectively connected with the first channel and the second channel, and the opening direction is away from the core direction.

[0010] Further, the femtosecond laser fiber grating writing system is used to write double-FBGs at the same node of the first core and the second core at the same time, to meet the splitting ratio requirement, to construct a reflective FBG detection node, and to realize temperature compensation.

[0011] Furthermore, the thin-wall cavity is constructed by removing a portion of the thin-wall layer of the first channel and the second channel by micromachining at the end face of the optical fiber to form a microdialysis microfluidic circuit.

[0012] Furthermore, the formation process of the dialysis membrane is as follows: using capillary action to absorb dimethyl sulfoxide-dissolved polysulfone and polyethylene glycol into a membrane-forming liquid column (35-55°C), solidifying through gel freezing, and then alternately using 70°C pure water and electrophoretic dialysis fluid to remove residual solvent, finally forming a microporous diffusion membrane.

[0013] A method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation comprises the following steps:

[0014] (1) Drawing of dual-channel dual-core optical fiber:

[0015] Ultrasonic drilling is performed on high-purity solid quartz preform rods, and then the inner wall of the preform rod hole is ground, polished and ultrasonically cleaned. Then, the rod assembly technology is used to complete the combination of the fiber core in the cladding and the fiber core inside the microhole and the annular cladding. The distance between the two fiber cores is adjusted to the minimum, and the preparation of the optical fiber preform rod is completed; the prepared preform rod is fixed on the optical fiber drawing tower, the stretching parameters are set, and air pressure is applied to the air hole of the preform rod for drawing, coating and winding.

[0016] (2) Construction of microdialysis channel and optofluidic electrophoresis channel:

[0017] A 157nm deep ultraviolet laser was used in conjunction with a nano-displacement stage to micro-machine the end face of the optical fiber to remove part of the thin-wall layer between the first and second channels, forming a thin-wall cavity and constructing a microdialysis microfluidic circuit. A dialysis membrane was prepared at the micro-machined structural site. Dimethyl sulfoxide was used to dissolve polysulfone and polyethylene glycol, and a membrane-forming liquid column (35-55°C) was absorbed by capillary action. The membrane was solidified by gel freezing. The residual solvent was removed alternately using 70°C pure water and electrophoresis dialysate to form a microporous diffusion membrane. An 800nm ​​femtosecond laser was used in conjunction with a nano-displacement stage to open holes in the first and second channels in the vertical direction of the dual-channel dual-core optical fiber. The position of the fiber core in the microstructured optical fiber was adjusted by a rotating device and detected by CCD imaging. The fiber core was moved away from the laser processing site. Finally, the sample inlet and sample outlet were connected to the first and second channels respectively, and a microinjection pump was connected to the sample inlet. Positive and negative microelectrodes were encapsulated on the surface of the dual-channel dual-core optical fiber to form a closed current loop with the electrophoresis instrument.

[0018] (3) Optical coupling and etching of integrated dual FBGs:

[0019] The ring and single-mode optical fiber and double-channel double-core optical fiber are coupled by using large-core fusion splicer and pull-taper machine to realize misalignment coupling fusion pull-taper; a wide-spectrum light source and a demodulator are connected, a femtosecond laser fiber grating writing system is used, and a 18SI81027 high-precision electric displacement table is used to directly write double FBG structures in the first and second cores at the same time, or a phase mask method is used to write double FBGs in the hydrogen-loaded microstructure double-channel double-core optical fiber, the photosensitive optical fiber is tightly attached to the phase mask, the ultraviolet laser is vertically irradiated on the mask, and the interference fringes of the ±1 order diffraction light are used to form the interference fringes of the light and dark in the near field to write the grating. The fiber coupling efficiency and the power distribution between the cores are controlled by parameters such as the taper angle, the stretched diameter and the taper length, and the power ratio of the two cores is monitored in real time by using a beam analyzer to meet the splitting ratio requirement.

[0020] (4) Modification of the sensitization material:

[0021] Two-dimensional nanomaterials such as graphene oxide and black phosphorus are grown on the surface of the second core by using a light-induced method to improve the sensitivity of the detection node; specifically, the 50-200 nm graphene oxide solution is introduced into the second channel to drive the deposition on the surface of the FBG by using the light pressure effect and thermal effect of the 1060 nm laser; the black phosphorus layer is grown by first using NaOH solution to make the core have -OH group, then using 3-aminopropyl triethoxysilane to connect -OH to make the surface have -NH2 group, and finally performing light-induced growth of black phosphorus.

[0022] (5) Regulation of electroosmotic flow by modification of the inner wall of the optical flow electrophoresis channel:

[0023] The silicon hydride on the inner wall of the optical fiber is bonded to remove negative charges and inhibit electroosmotic flow; the polyacrylamide is bonded to change the size of the electroosmotic flow; or the whey protein is combined to change the flow direction of the electroosmotic flow.

[0024] Further, in step (2), the dialysis membrane can be adjusted according to the size difference of the target molecules in the body, and the film-forming material, the proportion of the components and the solidification conditions are adjusted to adjust the microstructure of the dialysis membrane to ensure the induced dialysis of different target sizes such as protein molecules, DNA, amino acids, drugs and ions.

[0025] Further, before step (4), the inner wall of the second channel of the optical fiber can be modified by selective filling to change the charge, and the silicon hydride and negative charge on the inner wall of the optical fiber can be bonded with polydopamine to have strong adsorption and good biocompatibility; or the surface self-assembly of the cross-linked diazo resin with positive charge is used to form an optical fiber inner coating by using atom transfer radical polymerization to solve the adsorption problem of biological macromolecules such as proteins.

[0026] Compared with the prior art, the present application has the beneficial effects that:

[0027] (1) The wearable real-time sampling of the optical fiber in the body sample is realized by the "microdialysis" structure in the optical fiber, and the electric field is used to drive the complex sample to form an electroosmotic flow in the optical fiber, the In-fiber online separation of the complex components of the trace sample is realized by the difference in the charge-to-mass ratio, the inner wall of the second hole of the optical fiber is selectively filled to be charge-modified, so as to solve the problems of adsorption of biological macromolecules such as proteins and the problem that the optical fiber sensor cannot detect the complex mixed sample;

[0028] (2) The sensing unit node is designed in the microstructure optical fiber core, the In-fiber double FBGs structure modified by the two-dimensional layered nanomaterial is formed, the microflow is controlled by the electric field, the separated sample passes through the sensing unit, the effective refractive index at the sensitive unit is modulated by the separated sample, the temperature crosstalk is eliminated according to the difference in the resonance signal internal reference, and the outflow time information of each component biological sample is obtained, so as to realize the detection of the high-throughput multi-component sample in the optical fiber.

[0029] (3) The microdialysis structure and the electrophoretic separation structure are integrated in a single special optical fiber, a highly integrated In-fiber optical flow control online sensor device is constructed, the bottleneck problem of the existing optical fiber biological sensing which depends on the sample pretreatment outside the fiber is solved, the in-vivo complex sample collection, the online separation and detection of the multi-component microflow sample in the fiber are realized, and the device has the characteristics of automatic temperature compensation, high integration, high sensitivity and high stability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of an integrated optical fiber biological sensor for microdialysis sampling and rapid separation of multiple components;

[0031] Figure 2 is a cross-sectional view of a double-channel double-core optical fiber;

[0032] Figure 3 is a schematic diagram of the surface opening of a double-channel double-core optical fiber;

[0033] Figure 4 is a schematic diagram of the construction of a microdialysis confluence channel;

[0034] Figure 5 is a schematic diagram of the writing of the reference double FBGs in the double-channel double-core optical fiber. DETAILED DESCRIPTION

[0035] The following is a preferred embodiment of the present application, and it should be pointed out that, for ordinary skilled persons in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements are also considered to be within the protection scope of the present application.

[0036] Example 1

[0037] like Figure 1 As shown, an integrated optical fiber biosensor for microdialysis sampling and multi-component rapid separation includes a broadband light source 1, a transmission optical path 2, a circulator 3, a demodulator 4, a dialysis membrane 12, a microdialysis channel 5-1, an optofluidic electrophoresis channel 5-2, an inlet 6, an outlet 7, a microinjection pump 8, and an electrophoresis apparatus 9; the transmission optical path 2 is a single-mode optical fiber, one end of which is connected to the broadband light source 1 and the other end is coupled to port ① of the circulator 3, port ② of the circulator 3 is coupled to the dual-channel dual-core optical fiber 5, and port ③ of the circulator 3 is connected to the demodulator 4; the first channel of the dual-channel dual-core optical fiber 5 is the microdialysis channel 5-1 The second channel is the optofluidic electrophoresis channel 5-2, the first fiber core 5-3 is located in the annular cladding 5-5 of the optical fiber, and the second fiber core 5-4 is located on the inner surface of the second channel; the left end of the dual-channel dual-core optical fiber 5 has an inlet 6 and an outlet 7 respectively, and a microinjection pump 8 is connected to the inlet 6. The positive and negative microelectrodes 1011 are encapsulated on the surface of the dual-channel dual-core optical fiber 5, forming a closed current loop with the electrophoresis instrument 9. The first fiber core 5-3 and the second fiber core 5-4 located within the range of the positive and negative microelectrodes 1011 are etched with double FBGs13, and the end of the dual-channel dual-core optical fiber 5 has a thin-wall cavity, and the end face is encapsulated with a dialysis membrane 12.

[0038] Specifically, live mice such as C57BL / 6 and BALB / c nude mice, which are commonly used physiological and pathological animal experimental models, are used as online detection objects. By collecting complex amino acid components in the adipose tissue in the groin area, online detection of living biological metabolism is carried out.

[0039] After in vitro calibration, the end of a dual-channel, dual-core optical fiber 5 is inserted into a 19G medical needle and implanted into the inguinal adipose tissue of a live C57BL / 6 mouse. Appropriate concentrations of NaOH, HCl, MES, and Tris solutions are sequentially injected through the injection port 6 using a microinjection pump 8. The liquid flows through the thin-walled cavity along the microdialysis channel 5-3, flushing the optofluidic electrophoresis channel 5-4. Pre-electrophoresis equilibrium is performed using an electrophoresis apparatus 9, and waste liquid is discharged through the sample outlet 7. The inner diameter of the microdialysis channel 5-3 and the optofluidic electrophoresis channel 5-4 can be 60-75 μm and the length 15-20 cm. The electrophoresis microdialysis fluid is a pH 7.5 Ringers reagent consisting of NaCl, CaCl2, KCl, and MgSO4, plus boric acid buffer. To ensure accurate quantification, an amino acid derivatization reagent is simultaneously injected, using o-phthalaldehyde (OPA)-Na2SO3 or OPA-mercaptoethanol to react with amino acids in the dialysate before monitoring.

[0040] The experiment dialysis membrane 12 medium selects regenerated cellulose material, the dialysis membrane 12 reaches pressure balance by adjusting microflow dialysis parameter, due to the non-equilibrium concentration difference of amino acid inside and outside the optical fiber, various small molecule amino acids in adipose tissue pass through the dialysis membrane 12, are carried into the optical flow electrophoresis channel 5-4 by dialysate, and the electrophoresis instrument 9 and the positive and negative microelectrode 1011 form a closed loop, and separation is realized under the action of the electric field formed.The different amino acid molecules make the wavelength difference of double FBGs 13 change, and the optical signal returns from the double FBGs 13, is transmitted to the demodulator 4 through the circulator 3, the change amount of the demodulated delta lambda is related to the concentration after separation, and the change period corresponds to the separation time of amino acid, so that the standard amino acid molecule outflow fingerprint information spectrum can be established.Because the double FBGs 13 are located at the same position of the double-channel double-core optical fiber 5, they have the same temperature response, can form an internal reference, and the change amount of the central wavelength difference value delta lambda is independent of temperature. Even in the case that FBG is not sensitized and polarization state is not modulated, according to the minimum sensitivity of 8 nm / RIU of bare suspended core FBG refractive index, and the high-precision FBG demodulator 4 with a wavelength resolution of 0.1 pm, the minimum can be realized 1.2x10 -5 RIU high-resolution demodulation, the amino acid molecule detection limit LOD can reach 1-5 μmol / L, which is far lower than the in-vivo amino acid concentration. The time resolution can be controlled by controlling the FBG grating length and controlling the electrophoresis condition, and under the microdialysis flow rate of about 50 μL / min, the time resolution can reach 1-10 s, so that the in-vivo sensor can realize the transient detection of the body metabolism.

[0041] The application provides an integrated optical fiber biosensor which can realize in-vivo complex sample collection, online separation and detection of multiple components in the optical fiber, and has the characteristics of automatic temperature compensation, high integration, high sensitivity, high stability and the like. The optical fiber realizes wearable real-time collection of in-vivo samples through the "microdialysis" structure, and forms an electroosmotic flow in the optical fiber by driving the complex sample with an electric field, so as to realize In-fiber online separation of trace complex samples by the difference in charge-mass ratio. The inner wall of the second channel of the optical fiber is selectively filled and modified in electric charge to solve the problem of adsorption of biological macromolecules such as proteins and the problem that the optical fiber sensor cannot detect complex mixed samples. A sensing unit node is designed in the core of the microstructure optical fiber to form a two-dimensional layered nanomaterial modified sensitive In-fiber double FBG structure. The microflow is controlled by an electric field, so that the separated sample passes through the sensing unit, the effective refractive index of the separated sample at the sensitive unit is modulated, the temperature crosstalk is eliminated by the difference between the resonance signals of the internal reference, and the outflow time information of each component biological sample is obtained, so that high-throughput multi-component sample detection in the optical fiber is realized, and a rapid online analysis and detection method and an efficient approach are provided for the field of wearable medical sensing of optical fibers.

[0042] The application discloses an integrated optical fiber biosensor for microdialysis sampling and rapid separation of multiple components and a preparation method thereof, and comprises a wide-spectrum light source, a transmission light path, a circulator, a demodulator, a dialysis membrane, a microdialysis channel, an optofluidic electrophoresis channel, a sample inlet, a sample outlet, a micro-injection pump and an electrophoresis instrument; the preparation method comprises the following steps: drawing a microstructure optical fiber with a double-channel structure (a microdialysis channel and an optofluidic electrophoresis channel) and two fiber cores (one fiber core is located on the annular cladding of the optical fiber, and the other fiber core is located on the inner surface of the optofluidic electrophoresis channel); constructing a microdialysis microflow circuit and integrating the dialysis membrane in the optical fiber; opening holes in the microdialysis channel and the optofluidic electrophoresis channel in the vertical direction of the optical fiber respectively, realizing the circulating flow of the dialysate and the packaging of the microelectrode; preparing a double-FBG structure in the two fiber cores, and finally coupling the optical fiber to form a closed light path. The in-vivo sample diffusion collection is realized through the dialysis membrane, the microflow sample is separated in the optical fiber through the electric field, the electrophoresis microfluid medium in the optical fiber modulates the effective refractive index of the FBG cladding of the inner hanging fiber core, the FBG at the same position node of the annular cladding fiber core is used as an inner reference point, the double-FBG resonance wavelength difference is utilized to obtain the microflow liquid component signal, temperature compensation is obtained, and a high-throughput liquid flow time fingerprint spectrum is obtained. The application can solve the bottleneck problem that the existing optical fiber biosensing depends on the sample pretreatment outside the fiber, realize the integrated collection, separation and detection of complex samples at the in-vivo tissue, blood vessels and other parts, and promote the medical application of the optical fiber in-vivo / on-line biosensor.

Claims

1. A method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation, characterized in that The steps include: (1) Drawing of dual-channel dual-core optical fiber: Ultrasonic drilling is performed on a high-purity solid quartz preform rod. The inner wall of the preform rod hole is then ground, polished, and ultrasonically cleaned. Rod assembly technology is then used to complete the combination of the fiber core within the cladding and the fiber core inside the micropore with the annular cladding. The distance between the two fiber cores is adjusted to the minimum, thus completing the preparation of the optical fiber preform rod. The prepared preform rod is fixed on the optical fiber drawing tower, the drawing parameters are set, and air pressure is applied to the air holes of the preform rod. The fiber is then drawn, coated, and collected. (2) Construction of microdialysis channel and optofluidic electrophoresis channel: Using a 157nm deep ultraviolet laser coupled with a nano-displacement stage, the thin-wall layer between the first and second channels was partially removed by micromachining at the end face of the optical fiber to form a thin-wall cavity and construct a microdialysis microfluidic circuit. A dialysis membrane was prepared at the micromachined structure. Polysulfone and polyethylene glycol were dissolved in dimethyl sulfoxide, and a membrane-forming liquid column (35-55°C) was drawn into the membrane by capillary action. The membrane was solidified by gel freezing. Residual solvent was then removed by alternating use of 70°C pure water and electrophoresis dialysate to form a microporous diffusion membrane. Using an 800nm ​​femtosecond laser and a nanometer displacement stage, holes were opened on the surfaces of the first and second channels of a dual-channel, dual-core optical fiber in the vertical direction. The position of the fiber core in the microstructured optical fiber was adjusted using a rotating device and monitored using CCD imaging. The fiber core was moved away from the laser processing site. Finally, the inlet and outlet were connected to the first and second channels respectively, and a microinjection pump was connected to the inlet. Positive and negative microelectrodes were encapsulated on the surface of the dual-channel, dual-core optical fiber, forming a closed current loop with the electrophoresis instrument. (3) Optical coupling and etching of integrated dual FBGs: A large-core fusion splicer and a taper machine are used to stagger and couple the fused tapers to achieve coupling between the circulator and single-mode fiber and dual-channel dual-core fiber. A broadband light source and demodulator are connected, and a femtosecond laser fiber grating writing system is used in conjunction with the 18SI81027 high-precision motorized translation stage to simultaneously etch a dual FBG structure directly inside the first and second cores. Alternatively, a phase mask method is used to write dual FBGs into a microstructured dual-channel dual-core fiber after hydrogen loading. A photosensitive fiber is placed in close proximity to the phase mask, and an ultraviolet laser is used to perpendicularly illuminate the mask. The grating is written using phase interference of ±1st-order diffraction light to form alternating light and dark interference fringes in the near field. The fiber coupling efficiency and the optical power distribution between the cores are controlled by the parameters of the cone angle, stretching diameter, and cone length. A beam analyzer is used to monitor the power ratio between the two cores in real time to meet the splitting ratio requirements. (4) Modification of sensitizing materials: Using the photoinduced method, two-dimensional nanomaterials such as graphene oxide and black phosphorus are grown on the surface of the second fiber core to improve the sensitivity of the detection node. Specifically, the photoinduced growth of graphene oxide involves introducing a 50-200nm graphene oxide solution into the second channel, and using a 1060nm laser to excite the photopressure effect and thermal effect on the FBG surface to drive deposition on the FBG surface. The photoinduced growth of the black phosphorus layer involves first using a NaOH solution to impart -OH groups to the fiber core, then using 3-aminopropyltriethoxysilane to connect the -OH groups, imparting -NH2 groups to the surface, and finally performing photoinduced growth of black phosphorus. (5) Modification of the inner wall of the optofluidic electrophoresis channel to control electroosmotic flow: Organic silane is used to bond with the silanol group on the inner wall of the optical fiber to remove negative charges and inhibit electroosmotic flow; it is bonded with polyacrylamide to change the size of the electroosmotic flow; or it is combined with whey protein to change the direction of the electroosmotic flow.

2. The method for preparing the integrated optical fiber biosensor for microdialysis sampling and rapid separation according to claim 1, characterized in that: The integrated optical fiber biosensor for microdialysis sampling and rapid separation comprises a broadband light source (1), a transmission optical path (2), a circulator (3), a demodulator (4), a dialysis membrane (12), a microdialysis channel (5-1), an optofluidic electrophoresis channel (5-2), an injection port (6), an outlet port (7), a microinjection pump (8), and an electrophoresis apparatus (9); the transmission optical path (2) is a single-mode optical fiber, one end of the single-mode optical fiber is connected to the broadband light source (1), and the other end is coupled to port ① of the circulator (3), port ② of the circulator (3) is coupled to a dual-channel dual-core optical fiber (5), and port ③ of the circulator (3) is connected to the demodulator (4); the first channel of the dual-channel dual-core optical fiber (5) is the microdialysis channel (5-1), and the second channel is the microdialysis channel (5-1). The channel is an optofluidic electrophoresis channel (5-2), the first fiber core (5-3) is located in the annular cladding (5-5) of the optical fiber, and the second fiber core (5-4) is located on the inner surface of the second channel; the left end of the dual-channel dual-core optical fiber (5) is provided with an inlet (6) and an outlet (7), a microinjection pump (8) is connected to the inlet (6), positive and negative microelectrodes (10) (11) are encapsulated on the surface of the dual-channel dual-core optical fiber (5), and form a closed current loop with the electrophoresis instrument (9), the first fiber core (5-3) and the second fiber core (5-4) located within the range of the positive and negative microelectrodes (10) (11) are etched with double FBGs (13), the end of the dual-channel dual-core optical fiber (5) has a thin-wall cavity, and the end face is encapsulated with a dialysis membrane (12).

3. The method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation according to claim 2, characterized in that: The outer diameter of the dual-channel dual-core optical fiber (5) is 500 μm, and the distance between the first fiber core (5-3) and the second fiber core (5-4) should be minimized to ensure that the two fiber cores can be exposed simultaneously during the etching process of the dual FBGs (13), and at the same time, mode coupling between the first fiber core (5-3) and the second fiber core (5-4) should be avoided.

4. The method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation according to claim 2, characterized in that: The positions of the sample inlet (6) and the sample outlet (7) are perpendicular to the surface of the dual-channel dual-core optical fiber (5), respectively penetrating the first channel and the second channel, and the opening direction is away from the fiber core direction.

5. The method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation according to claim 1, characterized in that: In step (2), the dialysis membrane can adjust the membrane-forming material, component ratio and curing conditions according to the volume difference of the target molecules detected in vivo, and adjust the dialysis membrane microstructure to ensure the induced dialysis passage of different target size structures.

6. The method for preparing an integrated optical fiber biosensor for microdialysis sampling and rapid separation according to claim 1, characterized in that: Before step (4), the inner wall of the second channel of the optical fiber is charge-modified by selective filling, and the inner wall of the optical fiber is bonded with polydopamine by virtue of its silanol and negatively charged properties, thereby having strong adsorption and good biocompatibility; or a positively charged cross-linked diazo resin self-assembled on the surface is used to form a hydrophilic polydopamine / hyaluronic acid polymer into an inner coating of the optical fiber through atom transfer radical polymerization, so as to solve the adsorption problem of biological macromolecules such as proteins.

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