Fiber optic biosensor, flexible photonic crystal fiber and preparation method thereof

Abstract

This application discloses an optical fiber biosensor, a flexible photonic crystal fiber, and a preparation method thereof, relating to the field of optical fiber sensing technology. The preparation method comprises: preparing polyethylene glycol diacrylate, water, and a photocrosslinker according to a set mass ratio to obtain a hydrogel precursor; adding silica microspheres of a set particle size to the hydrogel precursor, performing ultrasonic dispersion and photocrosslinking and curing to obtain an intermediate of the hydrogel photonic crystal fiber; inserting this intermediate into a hydrofluoric acid solution of a set concentration and standing for a first set time to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure. By using a flexible photonic crystal fiber as the core of the optical fiber biosensor, this application can achieve high-sensitivity detection, has good stability, and is reusable. This can facilitate the application of optical fiber biosensors in practical situations, broaden the application field of optical fiber sensors, and product preparation.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensing technology, and in particular to an optical fiber biosensor, a flexible photonic crystal fiber, and a preparation method thereof. Background Art

[0002] Fiber optic sensing technology is one of the most mature and widely used technologies in today's detection field. Detection technology plays a vital role in human life today. Significant progress has been made in the detection of physical quantities such as temperature, stress, pressure, and magnetic fields. Fiber optic sensing technology has also achieved significant breakthroughs in biochemical detection. The detection of substances such as heavy metal ions, minerals, biomolecules, microorganisms, and viruses has become the mainstream direction of fiber optic sensing technology development, and fiber optic biosensing technology has also attracted much attention. However, fiber optic biosensing technology is still in its developmental stage. The preparation stability and sensing mechanism of the sensing unit are long-standing and unresolved issues in fiber optic biosensing technology. More critically, most fiber optic biosensors on the market are difficult to directly detect living organisms and have poor biocompatibility.

[0003] Fiber-optic biosensing technology, currently a major development area in fiber-optic sensing, has applications in fields such as biomedical testing and water quality monitoring. The main technical challenges of fiber-optic biosensing lie in the fabrication and signal processing of the fiber-optic sensing unit. Currently, fiber-optic biosensors are mainly categorized into fiber-optic fluorescence biosensors, fiber-optic SPR biosensors, fiber-optic Bragg grating (FBG) biosensors, fiber-optic Raman biosensors, and fiber-optic interferometry biosensors. Fiber-optic fluorescence biosensors offer the advantage of high sensitivity, but require fluorescent labeling, resulting in poor multiplexing and potential photobleaching. Fiber-optic SPR biosensors offer the advantages of label-free, real-time dynamic detection and high specificity, but require high equipment requirements and adsorbed substances can significantly affect the detection results. Fiber-optic Bragg grating (FBG) biosensors enable multi-parameter detection and are easily cascaded, but signal demodulation is complex and cross-sensitivity is severe. Fiber-optic Raman biosensors enable precise qualitative detection but require high equipment requirements. Fiber-optic interferometry biosensors enable multimodal detection of biomass quantities, but suffer from poor signal stability and complex fiber-optic sensing unit fabrication. Consequently, existing fiber-optic biosensors all have limitations, making the development of new fiber-optic biosensors of great significance. Summary of the Invention

[0004] The purpose of this application is to provide a fiber optic biosensor, a flexible photonic crystal fiber, and a preparation method thereof that can achieve high sensitivity, good stability, and be repeatedly used, so as to facilitate the application of fiber optic biosensors in practical situations and thereby broaden the application field and product preparation of fiber optic sensors.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a method for preparing a flexible photonic crystal fiber, comprising:

[0007] Polyethylene glycol diacrylate, water and a photocrosslinker were prepared in a mass ratio of 80:18:2 to obtain a hydrogel precursor;

[0008] After adding silica microspheres of a predetermined particle size into the hydrogel precursor, ultrasonic dispersion and photocrosslinking and curing are performed to obtain an intermediate of the hydrogel photonic crystal fiber;

[0009] The intermediate of the hydrogel photonic crystal fiber is inserted into a hydrofluoric acid solution of a set concentration and allowed to stand for a first set time to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure.

[0010] Optionally, the process of adding silica microspheres of a predetermined particle size to the hydrogel precursor, performing ultrasonic dispersion and photocrosslinking and curing to obtain an intermediate of the hydrogel photonic crystal fiber comprises:

[0011] Adding silica microspheres of a predetermined particle size to the hydrogel precursor, mixing and stirring to obtain a mixed solution;

[0012] Ultrasonic dispersion of silica microspheres in the mixed solution forms a three-dimensional photonic crystal structure in which the silica microspheres are periodically arranged;

[0013] After the three-dimensional photonic crystal structure is left to stand for a second set time, the mixed liquid in the three-dimensional photonic crystal structure is sucked into the silicone capillary by the capillary effect of the silicone capillary, and the connecting optical fiber is inserted to obtain an initial hydrogel photonic crystal fiber;

[0014] The initial hydrogel photonic crystal fiber is subjected to photo-crosslinking and curing to obtain an intermediate of the hydrogel photonic crystal fiber.

[0015] Optionally, the process of ultrasonically dispersing the silica microspheres in the mixed solution includes:

[0016] After inserting the ultrasonic instrument probe into the mixed liquid, ultrasonic waves are emitted for a set time to disperse the silica microspheres.

[0017] Optionally, the second set time is not less than 30 minutes.

[0018] Optionally, inserting the intermediate of the hydrogel photonic crystal fiber into a hydrofluoric acid solution of a set concentration and standing for a first set time to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure, comprising:

[0019] The intermediate of the hydrogel photonic crystal fiber is inserted into a hydrofluoric acid solution of a set concentration for at least 1 hour to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure.

[0020] In a second aspect, the present application provides a flexible photonic crystal fiber, which is prepared using the preparation method provided above, and includes: a fiber core and a hydrogel wrapping the fiber core; a hole structure is distributed in the hydrogel.

[0021] In a third aspect, the present application provides a fiber optic biosensor, comprising: a light source module, a fiber optic sensing unit, a signal acquisition and processing module, and a host computer;

[0022] The light source module, the optical fiber sensing unit and the signal acquisition and processing module are connected in sequence through transmission optical fibers; the signal acquisition and processing module is connected to the upper machine by electrical signals;

[0023] The optical fiber sensing unit is prepared by using the flexible photonic crystal optical fiber provided above; the optical fiber sensing unit is placed in the detection environment;

[0024] The optical fiber sensing unit is used to sense biological molecules in the detection environment based on the optical signal output by the light source module and output a modulated optical signal; the signal acquisition and processing module is used to acquire the modulated optical signal and convert the modulated optical signal into an electrical signal; the host computer is used to convert the electrical signal into spectral data and to obtain the concentration of biological molecules based on the spectral data.

[0025] Optionally, the light source module is a broadband light source; the optical signal emitted by the broadband light source includes an ultraviolet light band, a visible light band and a near-infrared band.

[0026] Optionally, the signal acquisition and processing module includes a fiber optic spectrometer.

[0027] Optionally, the preparation process of the optical fiber sensing unit includes:

[0028] The flexible photonic crystal optical fiber and the connecting optical fiber are photocured and connected by using ultraviolet glue to obtain the optical fiber sensing unit.

[0029] According to the specific embodiments provided in this application, this application has the following technical effects:

[0030] This application prepares a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure, and uses this flexible photonic crystal fiber as the core component of an optical fiber biosensor, so that during the detection process, the light signal passes through the controllable three-dimensional photonic crystal hole structure to achieve the effect of modulated light. Among them, the controllable three-dimensional photonic crystal hole structure can penetrate the biological molecules in the detection environment, thereby changing the wavelength modulation of the light signal to achieve the sensing purpose, thereby being able to realize biological qualitative and quantitative sensing detection based on the modulated light signal, and improving the detection sensitivity. The entire flexible photonic crystal fiber is prepared using hydrogel, has good biocompatibility and stability, and while being reusable, has the advantages of being small in size, can penetrate small molecules to block large molecules, and thus adapt to special biological environments, effectively realize biological detection and can be used for the detection of biological molecules in the human body, providing convenience for the application of optical fiber biosensors in actual situations, broadening the application field and product preparation of optical fiber sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic flow chart of a method for preparing a flexible photonic crystal fiber according to an embodiment of the present application;

[0033] Figure 2 A schematic diagram of the process for preparing an intermediate of a hydrogel photonic crystal fiber according to an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the preparation process of a flexible photonic crystal fiber and a fiber optic sensing unit provided in one embodiment of the present application;

[0035] Figure 4 A schematic diagram of the structure of an optical fiber biosensor provided in one embodiment of the present application;

[0036] Figure 5 This is a detection principle diagram of the optical fiber biosensor provided in one embodiment of the present application.

[0037] Reference numerals:

[0038] 1- Light source module, 2- Transmission optical fiber, 3- Optical fiber sensing unit, 4- Detection environment, 5- Signal acquisition and processing module, 6- Host computer, 7- Hydrogel, 8- Hole structure, 9- Fiber core, 10- Hydrogel precursor, 11- Silica microspheres, 12- Ultrasonic instrument probe, 13- Silicone capillary, 14- Connecting optical fiber, 15- UV glue. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0040] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0041] In an exemplary embodiment, the present application provides a method for preparing a flexible photonic crystal fiber, such as Figure 1 and Figure 2 As shown, the method includes:

[0042] Step 100: A hydrogel material, water, and a photocrosslinker are mixed in a predetermined ratio to obtain a hydrogel precursor 10. For example, polyethylene glycol diacrylate, water, and a photocrosslinker are mixed in a predetermined ratio (e.g., a mass ratio of 80:18:2) to obtain a hydrogel precursor 10. The ratio of the hydrogel material, water, and photocrosslinker can also be adjusted based on the application requirements.

[0043] Polyethylene glycol diacrylate is used as a precursor material, which has the characteristics of fast preparation and low cost.

[0044] Step 101: After adding silica microspheres 11 of a predetermined particle size to the hydrogel precursor 10, ultrasonic dispersion and photocrosslinking and curing are performed to obtain a hydrogel photonic crystal fiber intermediate. The implementation process of this step includes:

[0045] In step 1, silica microspheres 11 of a predetermined particle size are added to the hydrogel precursor 10 and mixed and stirred to obtain a mixed solution. For example, silica microspheres 11 of uniform particle size (200 nm) are added to the hydrogel precursor 10 and mixed and stirred until uniform. The size of the silica microspheres 11 can be adjusted according to the modulation wavelength to meet the output requirements of a specific wavelength. Furthermore, microspheres can be made of different materials and dispersed in the hydrogel precursor 10, such as heat-soluble opal microspheres, to facilitate the diverse preparation of flexible photonic crystal fibers.

[0046] In step 2, the silica microspheres 11 in the mixed solution are ultrasonically dispersed to form a three-dimensional photonic crystal structure in which the silica microspheres 11 are periodically arranged. For example, an ultrasonic instrument probe 12 is inserted into the thoroughly stirred mixture of the hydrogel precursor 10 and the silica microspheres 11, and ultrasonic dispersion is performed for 2 hours to achieve uniform dispersion of the silica microspheres 11, thereby facilitating the formation of a periodically arranged three-dimensional photonic crystal structure.

[0047] In step 3, after the 3D photonic crystal structure is allowed to stand for a second set time, the capillary effect of the silicone capillary 13 is used to draw the mixed solution from the 3D photonic crystal structure into the silicone capillary 13 and insert it into the connecting optical fiber 14, thereby obtaining the initial hydrogel photonic crystal fiber. After ultrasonic dispersion, the temperature of the mixed solution is relatively high. Based on this, the 3D photonic crystal structure can be allowed to stand for 30 minutes, and then the capillary effect of the silicone capillary 13 is used to draw the mixed solution into the tube and insert it into the connecting optical fiber 14. This completes the preparatory process for the hydrogel photonic crystal fiber, which has the advantages of simple operation and low dependence on equipment.

[0048] In step 4, the initial hydrogel photonic crystal fiber is photocrosslinked and cured to obtain a hydrogel photonic crystal fiber intermediate. For example, after the hydrogel photonic crystal fiber is prefabricated (i.e., the initial hydrogel photonic crystal fiber is obtained), it is placed under ultraviolet light to allow the polyethylene glycol diacrylate in the hydrogel precursor 10 to undergo photocrosslinking and curing with the photocrosslinker. After curing, the fiber can be extruded by air pressure or by injecting water to obtain a hydrogel photonic crystal fiber intermediate.

[0049] Step 102: The hydrogel-PCF intermediate is inserted into a hydrofluoric acid solution of a set concentration and allowed to stand for a first set time, thereby obtaining a flexible PCF with a controllable three-dimensional PCF hole structure. For example, the entire hydrogel-PCF intermediate is inserted into a 35% (by mass) hydrofluoric acid solution for one hour. The hydrofluoric acid solution corrodes the silica microspheres 11 in the hydrogel and the core of the connecting optical fiber 14, thereby forming a flexible PCF with a controllable three-dimensional PCF hole structure. This flexible PCF with a controllable three-dimensional PCF hole structure can adaptively adjust the effective refractive index and lattice constant of the photonic crystal when the hydrogel is in different environments, thereby achieving wavelength control of the optical signal.

[0050] Based on the above description, the overall preparation process of flexible photonic crystal fiber can be found in Figure 3 The pore structure of the hydrogel structure can be adjusted according to the concentration and ratio of the precursors, and it has good flexibility, hydrophilicity and biocompatibility.

[0051] In an exemplary embodiment, the present application provides a flexible photonic crystal fiber, which is prepared using the above-mentioned preparation method. Figure 4 As shown, the flexible photonic crystal fiber provided by the present application includes: a fiber core and a hydrogel wrapping the fiber core. The hydrogel has a hole structure distributed in it.

[0052] In an exemplary embodiment, the present application also provides an optical fiber biosensor, such as Figure 4 As shown, the optical fiber biosensor includes: a light source module 1, an optical fiber sensing unit 3, a signal acquisition and processing module 5 and a host computer 6.

[0053] The light source module 1, fiber optic sensing unit 3, and signal acquisition and processing module 5 are sequentially connected via a transmission optical fiber 2. The signal acquisition and processing module 5 is electrically connected to a host computer 6. The optical signal output by the light source module 1 is transmitted to the fiber optic sensing unit 3 for modulation and sensing. The optical signal output by the fiber optic sensing unit 3 is then transmitted to the signal acquisition and processing module 5 for signal acquisition and processing.

[0054] The optical fiber sensing unit 3 is placed in the detection environment 4. The optical fiber sensing unit 3 is prepared by using the flexible photonic crystal fiber provided above. Figure 3 As shown in the last part, the preparation process of the optical fiber sensing unit 3 can be as follows: the flexible photonic crystal fiber and the connecting optical fiber 14 are connected to form the optical fiber sensing unit 3 through the light curing of the ultraviolet glue 15. The ultraviolet glue 15 uses a resin with good biocompatibility as a base. The entire preparation process is simple to prepare, low-cost, and does not require expensive equipment for auxiliary operations. The optical fiber sensing unit 3 uses a flexible photonic crystal fiber for sensing biomolecules, and the silica microspheres 11 are ultrasonically dispersed in the hydrogel precursor 10 for photocrosslinking and curing. The silica microspheres 11 are then corroded deeply into the hydrogel precursor 10 by hydrofluoric acid to form periodically arranged spherical holes to form a three-dimensional photonic crystal structure. The input light is transmitted through the fiber core 9. During the process, the optical signal will pass through the surrounding three-dimensional photonic crystal structure to achieve the effect of modulating light. During the detection process, after the optical fiber sensing unit 3 is placed in the detection environment 4, the hole structure 8 of the flexible photonic crystal fiber can penetrate the biological small molecules in the detection environment 4 into the photonic crystal, and then modulate the wavelength of the input light signal, causing the light signal to change, thereby achieving the purpose of sensing.

[0055] In conjunction with the preparation method provided above, the fiber optic sensing unit 3 employed in this application utilizes a flexible photonic crystal fiber, prepared by etching silica microspheres 11 in a hydrogel 7 with hydrofluoric acid, as its core detection component. The substrate of the fiber optic sensing unit 3 is polyethylene glycol diacrylate, which exhibits excellent flexibility, hydrophilicity, and biocompatibility. Silica microspheres 11 of uniform particle size are uniformly dispersed in a hydrogel precursor 10 via ultrasonic dispersion, and a photocrosslinker is added, followed by curing by ultraviolet light. The hydrogel 7 has a porous structure, allowing small molecules to penetrate into the interior of the hydrogel 7 while large molecules are blocked from the outside. Biomolecules can penetrate into the photonic crystal lattice (the spherical cavities left after etching the silica microspheres 11) through the porous structure 8, thereby changing the lattice constant and effective refractive index to achieve qualitative and quantitative detection of biomolecules.

[0056] It is also possible to achieve uniform dispersion by replacing the material of the microspheres, such as degradable and low-melting-point plastics, and to prepare photonic crystal light simply by heating, or to introduce specially modified microspheres to specifically modify the photonic crystal cavity to achieve the detection of specific biomolecules.

[0057] Based on this, the optical fiber sensing unit 3 used in this application has good biocompatibility and flexibility, and has more application scenarios than traditional optical fiber biosensors. It is suitable for real-time monitoring on organisms. At the same time, it is fast to prepare and the process is simple, and it uses a new way of sensing, which fully broadens the application field of optical fiber biosensors.

[0058] The fiber optic sensing unit 3 utilizes the pore structure 8 of the hydrogel 7 to change pore size and infiltrate biomolecules in response to changes in the external environment. Specific aptamers or antibodies can be modified on the surface of the photonic crystal or within the pores. Binding to the substance to be detected can alter the lattice constant and effective refractive index of the photonic crystal, thereby altering the light modulation, such as shifting the wavelength of the emitted light. Calibration can then be performed based on the amount of wavelength shift, the intensity of the optical signal, and changes in the external environment or the concentration of the biomolecules, ultimately enabling qualitative and quantitative biological sensing. The entire fiber optic sensing unit 3, fabricated using hydrogel 7, exhibits excellent biocompatibility and a compact size. It can penetrate small molecules while blocking large molecules, adapting to specific biological environments and enabling detection of biomolecules within the human body. It has broad application prospects in fields such as human health and medical testing, and is expected to achieve widespread adoption of fiber optic biosensors.

[0059] Furthermore, to facilitate wavelength modulation of broadband input light by the optical fiber sensing unit 3 and facilitate the control and selection of the photonic crystal and lattice constant in the optical fiber sensing unit 3, the light source module 1 used in this application can be a broadband light source. The optical signal emitted by the broadband light source includes the ultraviolet light band, the visible light band, and the near-infrared band.

[0060] Based on the above description, the fiber optic sensing unit 3 is fabricated using hydrogel 7 as its base material. To ensure light transmission efficiency, reduce light scattering, and enhance total light reflection within the fiber optic sensing unit 3, a layer of low-refractive-index hydrogel can be solidified on the outside of the fiber optic sensing unit 3 after fabrication (by changing the ratio or type of precursors). This serves as a cladding layer, enhancing total light reflection within the fiber optic sensing unit 3 and reducing light loss, thereby optimizing the fiber optic sensing unit 3 and increasing the intensity of the final detection signal. Furthermore, the size of the pores allows for precise screening and filtration based on the size of the biomolecules being detected, enhancing the sensor's specific detection capabilities. Based on the characteristics of the cladding, the pores can be used to detect small biomolecules within the cladding, enabling multi-parameter detection of biomacromolecules within the cladding, enabling applications in a wider range of situations.

[0061] Based on the above description of the present application, by modifying the surface of the hydrogel 7 with functional materials such as antibodies, specific detection of some viruses or bacteria can be achieved, thereby broadening the scope and types of detection and further realizing applications in the medical field.

[0062] By employing different periodic structures (i.e., controllable three-dimensional photonic crystal hole structures), one-, two-, or three-dimensional fiber optic sensing units 3 can be formed, enabling diverse light control mechanisms, such as dual-band light control and polarization control. This setup allows for the design and fabrication of photonic crystal structures tailored to the control wavelength range and sensing sensitivity. Fabrication can be accomplished simply by etching or heating the material, further simplifying the fabrication process for the photonic crystal structures within the fiber optic sensing units 3.

[0063] In another exemplary embodiment of the present application, the signal acquisition and processing module 5 may include a fiber optic spectrometer. The detection range of the fiber optic spectrometer covers the ultraviolet, visible, and infrared light bands, making it easy to detect optical signals from broadband light sources, achieve background light removal, and convert signal light modulated by the fiber optic sensing unit 3. After the optical signal is transmitted to the fiber optic spectrometer through the transmission optical fiber 2, the fiber optic spectrometer converts the optical signal into an electrical signal and transmits it to the host computer 6 (such as a computer or other intelligent device with visual display). The host computer 6 receives the electrical signal from the fiber optic spectrometer, converts the electrical signal into spectral data including the spectral signal, and presents the obtained spectral data on a display. Based on this, the wavelength of the modulated light can be calibrated according to the concentration of the biomolecules measured by the fiber optic sensing unit 3 to determine the calibration relationship. Then, the biomolecules can be qualitatively and quantitatively detected in real time based on the determined calibration relationship.

[0064] Furthermore, fiber-optic biosensors based on flexible photonic crystal fibers utilize hydrogel 7 as their matrix, exhibiting excellent flexibility and biocompatibility. They are capable of real-time detection deep within living organisms and selectively screen biomolecules that enter the detection region (within the hydrogel 7), demonstrating a certain degree of specificity. Based on the above description, fiber-optic biosensors are easy to prepare, require a short process, and are low-cost, facilitating their commercialization. Flexible photonic crystal fibers exhibit reversible light control, excellent stability, and repeatability, facilitating the widespread adoption and application of fiber-optic biosensors.

[0065] Furthermore, in actual applications, the raw material of the hydrogel 7 can be changed according to the application of the optical fiber sensing unit 3, such as polyacrylamide, to provide the optical fiber sensing unit 3 with unique properties, such as hydrophobicity, electromagnetic sensitivity, or birefringence, enabling sensing and detection applications in more scenarios and for sensing and detecting more biomolecules. Functional materials can also be added to the hydrogel 7 to impart hydrophobicity and magnetic induction polarization properties to the optical fiber sensing unit 3, thereby improving or increasing the functionality of the optical fiber sensing unit 3.

[0066] In another exemplary embodiment of the present application, Figure 5 As shown, the detection principle of the optical fiber biosensor is:

[0067] The optical fiber sensing unit 3 receives the broadband optical signal (i.e., broadband light source spectrum) input by the light source module 1 through the transmission optical fiber 2. After being modulated by the flexible photonic crystal fiber in the optical fiber sensing unit 3, the broadband light signal is modulated according to the modulation formula There will be a photonic band gap central wavelength Transmission spectrum. It contains a When the biomolecule to be tested passes through the hole structure 8 of the hydrogel 7 and enters the photonic crystal (i.e., three-dimensional photonic crystal structure) in the flexible photonic crystal fiber, the effective refractive index of the photonic crystal is The modulation of light by the photonic crystal will change, the central wavelength of the narrowband loss peak will also change, and the transmission spectrum will have a corresponding wavelength drift. When sensitive substances such as antibodies are modified on the hydrogel 7, they will cause the structure of the hydrogel 7 to change after binding with biological molecules, so that the hydrogel 7 can adaptively adjust the hole structure 8 to change the structure of the photonic crystal, ultimately affecting the lattice constant of the photonic crystal. , which causes the photonic crystal to be sensitive to the central wavelength of the optical signal. The central wavelength of the narrowband loss peak of the transmission spectrum will also drift due to the change of the control. Different biomolecule concentrations will cause the effective refractive index of the photonic crystal to and lattice constant Regular changes occur, so it is possible to calibrate by establishing the relationship between the amount of wavelength drift and the concentration or number of biomolecules, and perform qualitative and quantitative detection of biomolecules.

[0068] Based on the above description, the photonic crystal based on the hydrogel 7 has good hydrophilicity and biocompatibility. It can modulate the optical signal according to the changes in the internal corrosion holes and the changes in the effective refractive index of the holes to achieve the output of light of a specific wavelength. The signal light passing through the optical fiber sensing unit 3 enters the optical fiber spectrometer through the transmission optical fiber 2 and is collected and analyzed by the optical fiber spectrometer. The host computer 6 is connected to the signal acquisition and processing module 5 via a data line, converts the signal collected and processed by the optical fiber spectrometer into an electrical signal, and then performs subsequent data processing. The entire optical fiber biosensor can be placed in the environment to be tested. The biomolecules enter the corroded photonic crystal structure of the optical fiber through the hole structure 8 of the hydrogel 7, achieving a change in the effective refractive index, or by changing the lattice constant of the photonic crystal by combining with the hydrogel 7, thereby achieving different regulation of the optical signal. By detecting the optical signal and calibrating its relationship with the number or concentration of the biomolecules to be tested, qualitative and quantitative detection can be achieved.

[0069] In summary, compared to the prior art, the solution provided by this application has the following advantages:

[0070] 1. This application uses hydrogel as a precursor to prepare a fiber optic sensing unit. The hydrogel is photocrosslinked and cured into an optical fiber. This method is simple, rapid, and requires minimal equipment and operation. Compared to traditional fiber optic sensing units, it exhibits superior hydrophilicity and biocompatibility. The pore structure allows for the permeation of biomolecules, and the pore size of the photonic crystal fiber can be adjusted based on the precursor ratio to screen for analytes. Due to its excellent biocompatibility, the fiber optic sensing unit can be directly introduced into a living organism without triggering a biological rejection reaction, enabling real-time monitoring.

[0071] 2. This application uses the method of corroding uniformly dispersed silica microspheres to construct a photonic crystal structure in a hydrogel. Compared with the preparation of conventional photonic crystal fibers, it is simpler and faster, and has lower costs and less difficulty in preparation. By using microspheres of different particle sizes, it is possible to achieve regulation of different amplitudes of light signals, and using microspheres of different materials and methods to construct photonic crystal structures, it has higher flexibility than the preparation of traditional photonic crystal fibers. Modified microspheres can also be introduced during the preparation process to retain sensitive substances in the hydrogel, achieving a variety of sensing and broadening the application field of optical fiber biosensors based on flexible photonic crystal fibers.

[0072] 3. This application uses a flexible photonic crystal fiber prepared based on hydrogel as a fiber optic sensing unit, which has good flexibility and can realize the regulation of the input light signal through the extensible hole structure of the hydrogel. Under changes in the environment, the hydrogel will cause the lattice constant of the corroded photonic crystal structure to change adaptively, that is, the change in size causes the change in light regulation. It can also change the internal refractive index through the biological small molecules entering the hydrogel, thereby changing the light regulation effect and realizing a new type of biosensing method. Compared with traditional fiber optic biosensors, this application has better stability and reusability. Compared with the fiber optic biosensors that have been commercialized, this application adopts a new sensing principle, with more diverse design schemes and a wider range of regulation, which can broaden the application fields and scenarios of fiber optic biosensors.

[0073] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for preparing a flexible photonic crystal fiber, characterized in that: include: Polyethylene glycol diacrylate, water and a photocrosslinker were prepared in a mass ratio of 80:18:2 to obtain a hydrogel precursor; After adding silica microspheres of a predetermined particle size into the hydrogel precursor, ultrasonic dispersion and photocrosslinking and curing are performed to obtain an intermediate of the hydrogel photonic crystal fiber; Inserting the hydrogel photonic crystal fiber intermediate into a hydrofluoric acid solution of a set concentration and allowing it to stand for a first set time results in a flexible photonic crystal fiber having a controllable three-dimensional photonic crystal hole structure. The flexible photonic crystal fiber adaptively adjusts the effective refractive index and lattice constant of the photonic crystal when the hydrogel is in different environments. The hole structure of the flexible photonic crystal fiber is capable of permeating small biological molecules in the detection environment into the photonic crystal, thereby modulating the wavelength of the input light signal, causing the light signal to change and achieving a sensing purpose. The process of adding silica microspheres of a predetermined particle size to the hydrogel precursor, performing ultrasonic dispersion and photocrosslinking and curing to obtain an intermediate of the hydrogel photonic crystal fiber comprises: Adding silica microspheres of a predetermined particle size to the hydrogel precursor, mixing and stirring to obtain a mixed solution; Ultrasonic dispersion of silica microspheres in the mixed solution forms a three-dimensional photonic crystal structure in which the silica microspheres are periodically arranged; After the three-dimensional photonic crystal structure is left to stand for a second set time, the mixed liquid in the three-dimensional photonic crystal structure is sucked into the silicone capillary by the capillary effect of the silicone capillary, and the connecting optical fiber is inserted to obtain an initial hydrogel photonic crystal fiber; The initial hydrogel photonic crystal fiber is subjected to photo-crosslinking and curing to obtain an intermediate of the hydrogel photonic crystal fiber.

2. The method for preparing a flexible photonic crystal fiber according to claim 1, wherein: The process of ultrasonically dispersing the silica microspheres in the mixed solution includes: After inserting the ultrasonic instrument probe into the mixed liquid, ultrasonic waves are emitted for a set time to disperse the silica microspheres.

3. The method for preparing a flexible photonic crystal fiber according to claim 1, wherein: The second set time is not less than 30 minutes.

4. The method for preparing a flexible photonic crystal fiber according to claim 1, wherein: Inserting the intermediate of the hydrogel photonic crystal fiber into a hydrofluoric acid solution of a set concentration and standing for a first set time to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure, comprising: The intermediate of the hydrogel photonic crystal fiber is inserted into a hydrofluoric acid solution of a set concentration for at least 1 hour to obtain a flexible photonic crystal fiber with a controllable three-dimensional photonic crystal hole structure.

5. A flexible photonic crystal fiber, characterized in that: The flexible photonic crystal fiber is prepared by the preparation method according to any one of claims 1 to 3; the flexible photonic crystal fiber comprises: a core and a hydrogel wrapping the core; and a hole structure is distributed in the hydrogel.

6. An optical fiber biosensor, characterized in that: include: Light source module, optical fiber sensing unit, signal acquisition and processing module and host computer; The light source module, the optical fiber sensing unit and the signal acquisition and processing module are connected in sequence through transmission optical fibers; the signal acquisition and processing module is connected to the upper machine by electrical signals; The optical fiber sensing unit is prepared by using the flexible photonic crystal fiber according to claim 5; the optical fiber sensing unit is placed in a detection environment; The optical fiber sensing unit is used to sense the biological molecules in the detection environment based on the optical signal output by the light source module, and output a modulated optical signal; the signal acquisition and processing module is used to acquire the modulated optical signal and convert the modulated optical signal into an electrical signal; the host computer is used to convert the electrical signal into spectral data, and to obtain the concentration of the biological molecules based on the spectral data; wherein, the optical fiber sensing unit is a flexible photonic crystal optical fiber prepared by corroding silica microspheres in hydrogel with hydrofluoric acid as the core detection component; the hydrogel has a porous structure that allows small molecules to penetrate into the interior of the hydrogel, while large molecules are blocked on the outside. The biological molecules penetrate into the spherical cavity left after the silica microspheres are corroded through the porous structure, changing the lattice constant and effective refractive index, thereby realizing qualitative and quantitative detection of the biological molecules.

7. The optical fiber biosensor according to claim 6, characterized in that The light source module is a broadband light source; the optical signal emitted by the broadband light source includes ultraviolet light band, visible light band and near infrared band.

8. The optical fiber biosensor according to claim 6, wherein: The signal acquisition and processing module includes a fiber optic spectrometer.

9. The optical fiber biosensor according to claim 6, wherein: The preparation process of the optical fiber sensing unit includes: The flexible photonic crystal optical fiber and the connecting optical fiber are photocured and connected by using ultraviolet glue to obtain the optical fiber sensing unit.

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