Optical fiber SPR sensor and detection system based on optical fiber SPR sensor

Abstract

The utility model discloses an optical fiber SPR (Surface Plasmon Resonance) sensor and a detection system based on the optical fiber SPR sensor. The optical fiber SPR sensor comprises a sensing substrate, a first electrode and a second electrode, the metal film is fixedly arranged outside the induction base body, and the metal film wraps the induction base body; and the monosulfide layer is fixedly arranged outside the metal film. By changing the structure of the sensing substrate and adopting the monosulfide layer, the electric field intensity of surface plasma coupling is enhanced, and the sensitivity of the optical fiber SPR sensor is improved; meanwhile, the optical fiber SPR sensor has stability and repeatability, and the working reliability of the optical fiber SPR sensor in actual biological detection is further enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, in particular to an optical fiber SPR sensor and a detection system based on the optical fiber SPR sensor. Background Art

[0002] Surface plasmon resonance (SPR) refers to an optical phenomenon in which electromagnetic waves resonate with plasma waves (SPW) on the metal surface at the interface between metal and dielectric, resulting in a reduction in reflection intensity. In recent years, fiber-optic SPR sensors have become a new detection method in the field of biosensing. Traditional detection technologies have problems such as limited sensitivity, cumbersome operation, and long detection time. The emergence of fiber-optic SPR sensors makes up for the shortcomings of traditional electrochemical sensors in biological detection. The advantages of fiber-optic SPR biosensors such as high sensitivity, label-free, and real-time detection make them the only choice for sensor research in this direction.

[0003] However, conventional fiber-optic SPR sensors have poor stability and cannot meet the requirements of higher-precision detection due to their sensitivity. When detecting biomolecules with lower molecular weight and ultra-low concentration, they cannot detect tiny changes in optical parameters. Utility Model Content

[0004] The utility model aims to solve at least one of the technical problems existing in the prior art or related technology.

[0005] In view of this, the utility model provides an optical fiber SPR sensor and a detection system based on the optical fiber SPR sensor, wherein the optical fiber SPR sensor can enhance the electric field intensity of surface plasma coupling by changing the structure of the sensing matrix and adopting a single sulfide layer, thereby improving the sensitivity of the optical fiber SPR sensor; at the same time, the optical fiber SPR sensor has both stability and repeatability, further enhancing the working reliability of the optical fiber SPR sensor in actual biological detection.

[0006] Specifically, the following technical solutions are included:

[0007] The embodiment of the first aspect of the utility model provides an optical fiber SPR sensor, the optical fiber SPR sensor comprising:

[0008] Sensing matrix;

[0009] A metal film is fixedly arranged outside the sensing substrate, and the metal film wraps the sensing substrate;

[0010] The monosulfide layer is fixedly disposed outside the metal film.

[0011] Optionally, the sensing substrate is a multimode optical fiber with the coating removed, and the length of the multimode optical fiber is 1.5 cm to 2.2 cm.

[0012] Optionally, the multimode optical fiber is U-shaped, and the radius of curvature of the U-shaped multimode optical fiber is 0.5 mm to 2 mm.

[0013] Optionally, the multimode optical fiber with the coating removed further comprises a cladding and a core disposed in the cladding, the diameter of the cladding is 120 μm to 130 μm, and the diameter of the core is 60 μm to 65 μm.

[0014] Optionally, the metal film is Au, Ag, Al or Cu, and the metal film is fixed to the sensing substrate by sputtering through an ion sputtering apparatus.

[0015] Optionally, the thickness of the metal film is 50 nm.

[0016] Optionally, the monosulfide layer is a germanium sulfide film, and the germanium sulfide film is fixed outside the metal film by electrostatic self-assembly.

[0017] Optionally, the germanium sulfide film has a thickness of 5 nm to 20 nm.

[0018] Optionally, the optical fiber SPR sensor includes two connectors, namely a first connector and a second connector, the first connector is connected to a halogen light source, and the second connector is connected to a spectrometer.

[0019] The embodiment of the second aspect of the present utility model provides a detection system based on an optical fiber SPR sensor, the detection system comprising:

[0020] As the above-mentioned optical fiber SPR sensor, the optical fiber SPR sensor is disposed in a solution to be tested;

[0021] A halogen light source connected to the first connector of the optical fiber SPR sensor;

[0022] A spectrometer, wherein the input end of the spectrometer is connected to the second connector of the optical fiber SPR sensor, and the output end of the spectrometer is connected to a remote terminal.

[0023] The optical fiber SPR sensor and the detection system based on the optical fiber SPR sensor provided by the embodiment of the utility model, wherein the optical fiber SPR sensor comprises a sensing substrate, a metal film and a monosulfide layer, the metal film is wrapped outside the sensing substrate, and the monosulfide layer is wrapped outside the metal film. Through the setting of the monosulfide layer, it has a higher carrier mobility and a high absorption coefficient, and exhibits good absorption characteristics in a wide wavelength range. Therefore, the addition of the monosulfide layer can promote the charge transfer between the metal film and the monosulfide layer, strengthen the free electron resonance, increase the electric field strength of the surface plasma resonance coupling, and improve the detection accuracy of small molecules; at the same time, changing the structure of the sensing substrate makes the optical fiber SPR sensor have good stability, strengthens the working reliability of the optical fiber SPR sensor in actual biological detection, and the optical fiber SPR sensor of the present application is also reusable, which improves the economy of detection.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic diagram of the structure of an optical fiber SPR sensor according to an embodiment of the utility model;

[0027] Figure 2 is a cross-sectional schematic diagram of an optical fiber SPR sensor according to an embodiment of the utility model;

[0028] Figure 3 A schematic diagram of a detection system based on the optical fiber SPR sensor according to an embodiment of the utility model;

[0029] Figure 4 It is a transmission spectrum diagram of a detection system based on an optical fiber SPR sensor according to an embodiment of the utility model;

[0030] Figure 5 A sensitivity fitting curve diagram of a detection system based on an optical fiber SPR sensor according to an embodiment of the utility model;

[0031] Figure 6It is a transmission spectrum diagram of the detection system of the existing optical fiber SPR sensor;

[0032] Figure 7 This is a sensitivity fitting curve diagram of the detection system of the existing optical fiber SPR sensor.

[0033] in, Figures 1 to 3 The corresponding relationship between the reference numerals and the component names is as follows:

[0034] 10. optical fiber SPR sensor, 11. multimode optical fiber, 12. metal film, 13. germanium sulfide film, 14. connector, 20. solution to be tested, 30. light source, 40. spectrometer, 50. remote terminal. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] Before further describing the embodiments of the present invention in detail, the directional terms involved in the embodiments of the present invention, such as "upper part", "lower part" and "side part", do not have the meaning of limiting the protection scope of the present invention.

[0037] In order to make the technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0038] Figure 1 A schematic diagram of the structure of an optical fiber SPR sensor according to an embodiment of the utility model; Figure 2 It is a cross-sectional schematic diagram of a fiber SPR sensor according to an embodiment of the utility model.

[0039] like Figure 1 and Figure 2 As shown, an embodiment of the utility model provides a fiber SPR sensor, the fiber SPR sensor 10 comprises:

[0040] Sensing matrix;

[0041] The metal film 12 is fixedly arranged outside the sensing substrate, and the metal film 12 wraps the sensing substrate;

[0042] The monosulfide layer is fixedly disposed outside the metal film 12 .

[0043] The optical fiber SPR sensor 10 includes a sensing substrate, a metal film 12 and a monosulfide layer, wherein the metal film 12 is wrapped outside the sensing substrate, and the monosulfide layer is wrapped outside the metal film 12. The monosulfide layer has a high carrier mobility and a high absorption coefficient, and exhibits good absorption characteristics in a wide wavelength range. Therefore, the addition of the monosulfide layer can promote the charge transfer between the metal film 12 and the monosulfide layer, strengthen the free electron resonance, increase the electric field strength of the surface plasma resonance coupling, and improve the detection accuracy of small molecules; at the same time, the structure of the sensing substrate is changed so that the optical fiber SPR sensor 10 has good stability, and the working reliability of the optical fiber SPR sensor 10 in actual biological detection is enhanced. The optical fiber SPR sensor 10 of the present application is also reusable, which improves the economy of using the optical fiber SPR sensor 10 for detection.

[0044] In a feasible implementation manner, the sensing substrate is a multimode optical fiber 11 with the coating removed, and the length of the multimode optical fiber 11 is 1.5 cm to 2.2 cm.

[0045] Among them, the surface of the multimode optical fiber 11 is an elastic coating composed of acrylate, silicone rubber and nylon, etc., which is used to protect the cladding and core of the multimode optical fiber 11. The coating on the surface of the multimode optical fiber 11 is stripped by Miller clamps, and the elastic material remaining on the surface of the multimode optical fiber 11 is repeatedly cleaned and removed with alcohol and deionization, and then the surface of the multimode optical fiber 11 is dried. The length of the multimode optical fiber 11 is 1.5cm to 2.2cm. The multimode optical fiber 11 of this part is used as the sensing area of ​​the optical fiber SPR sensor 10. In practical applications, the setting of the length parameters of the multimode optical fiber 11 will affect the preparation difficulty and detection effect of the optical fiber SPR sensor 10. When the length is too long, the corresponding sensing area becomes longer, resulting in an increase in the detection amount of the required solution 20 to be tested, increasing the detection cost; when the length is too short, the manufacturing difficulty of the connector 14 of the optical fiber SPR sensor 10 increases, and it will also have an adverse effect on the actual detection effect. Optionally, the length of the multimode optical fiber 11 is 2cm.

[0046] In a feasible implementation manner, the multimode optical fiber 11 is U-shaped, and the curvature radius of the U-shaped multimode optical fiber 11 is 0.5 mm to 2 mm.

[0047] Among them, the sensing matrix adopts a multimode optical fiber 11, and adopts a U-shaped structure. The multimode optical fiber 11 with a U-shaped structure has a strong evanescent field, which makes the optical fiber SPR sensor 10 have a huge high-sensitivity sensing potential; the multimode optical fiber 11 with a U-shaped structure can also promote the evanescent wave (EW) interaction with the surrounding medium, and has a high EW absorbance sensitivity. At the same time, the preparation of the U-shaped structure is relatively simple, and it is more solid than other shapes, has good stability, and is relatively easy to contact with the solution to be tested 20. At the same time, the two connectors 14 can be located at a position above the solution to be tested 20, which is convenient for the use of the optical fiber SPR sensor 10, that is, it is more convenient for detection.

[0048] Specifically, the coating of the multimode optical fiber 11 is removed to avoid the coating caused by subsequent burning turning into ash and adhering to the cladding, affecting the coating of the film layer and affecting the improvement of the sensitivity of the optical fiber SPR sensor 10. The multimode optical fiber 11 from which the coating is removed is bent, the two ends of the multimode optical fiber 11 are clamped with tweezers and fixed on a metal frame, the multimode optical fiber 11 is repeatedly rinsed with alcohol and deionized water, and repeatedly rinsed four to seven times, and the surface of the multimode optical fiber 11 is dried. The multimode optical fiber 11 is evenly burned with an alcohol lamp until the fixed shape of the multimode optical fiber 11 is U-shaped. The radius of curvature of the U-shaped curved part is too large to cause the sensitivity of the optical fiber SPR sensor 10 to decrease, resulting in poor detection performance, and the radius of curvature is too small to cause the resonance trough to become shallow, and the stability and anti-interference ability to decrease. In the present embodiment, the radius of curvature selects 1mm.

[0049] In a feasible implementation manner, the diameter of the multimode optical fiber 11 without coating includes a cladding and a core disposed in the cladding, the diameter of the cladding is 120 μm to 130 μm, and the diameter of the core is 60 μm to 65 μm.

[0050] In this embodiment, the cladding diameter of the multimode optical fiber 11 used for the test is 125 μm, and the core diameter is 62.5 μm. The multimode optical fiber 11 can be purchased and will not be described in detail.

[0051] In a feasible implementation manner, the metal film 12 is Au, Ag, Al or Cu, and the metal film 12 is fixed to the sensing substrate by sputtering through an ion sputtering device.

[0052] Among them, the metal film 12 uses a metal with a high reflectivity, so Au, Ag, Al or Cu is usually selected as the material of the metal film 12. In addition to considering the reflectivity, the stability of the metal film 12 will also affect the stability and reliability of the optical fiber SPR sensor 10. Therefore, optionally, the metal film 12 is made of Au or Ag. The metal film 12 in this embodiment is made of Au, that is, a gold film. Au has the best stability, is not easy to react with other substances, is chemically inert, is suitable for long-term use, can facilitate the repeated use of the optical fiber SPR sensor 10, and improves the production economy of the optical fiber SPR sensor 10.

[0053] It should be noted that the U-shaped multimode optical fiber 11 to be coated is placed in an ion sputtering apparatus so that the metal film 12 is evenly fixed on the surface of the multimode optical fiber 11 by ion sputtering. During the entire coating process, the vacuum chamber needs to maintain a high vacuum.

[0054] In a feasible implementation, the thickness of the metal film 12 is 40 nm to 70 nm.

[0055] Among them, when the thickness of the metal film 12 is less than 40nm, the electric field intensity of plasma coupling is low, and the effect of improving the sensitivity of the optical fiber SPR sensor is not obvious; when the thickness of the metal film 12 exceeds 70nm, the thickness is too high, resulting in a shallower resonance trough and a lower signal-to-noise ratio, which affects the stability of the optical fiber SPR sensor.

[0056] It should be noted that the discharge time and current of the ion sputtering apparatus are adjusted so that the thickness of the metal film 12 is controlled at 50 nm.

[0057] In a feasible implementation manner, the single sulfide layer is a germanium sulfide film 13 , and the germanium sulfide film 13 is fixed on the outside of the metal film 12 by electrostatic self-assembly.

[0058] Wherein, the germanium sulfide film 13 adopts the mode of electrostatic self-assembly to be fixed on the outside of the metal film 12, specifically, first 3ml chitosan solution (1g chitosan is dissolved in 100mL 4% glacial acetic acid aqueous solution) is added to 3ml concentration and is in the germanium sulfide nanosheet dispersion liquid of 1mg / ml, and fully stirs. Subsequently, the mixed solution of chitosan and germanium sulfide is ultrasonically treated for 15min under 280W at power, and the solution after the treatment presents reddish brown. In the glacial acetic acid aqueous solution, the amino group of chitosan is easily ionized, and the protonated amino group can be combined with some anionic substances by electrostatic attraction, that is to say, the chitosan solution is positively charged. Before realizing electrostatic self-assembly, the U-shaped multimode optical fiber 11 with a metal film 12 is immersed in a 4-sodium styrene sulfonate (PSS) solution for 9 to 11 minutes, and the metal film 12 is negatively charged, that is, the negatively charged anionic polymer PSS is fixed on the metal film 12. At this time, the chitosan solution is positively charged and can be combined with the negatively charged anionic polymer PSS, so that the mixed solution of chitosan and germanium sulfide can be fixed on the metal film 12 coated with PSS. This is the way of electrostatic self-assembly. Similarly, the connector 14 of the dried optical fiber SPR sensor 10 is immersed in a mixed solution of chitosan and germanium sulfide. After soaking for 3 to 5 hours, the optical fiber SPR sensor 10 is taken out, and the germanium sulfide film 13 is obtained after standing at room temperature for 19 to 21 hours, that is, the optical fiber SPR sensor 10 of the present application is obtained.

[0059] It should be noted that the addition of the germanium sulfide film 13 can promote the charge transfer between the metal film 12 and the germanium sulfide film 13 , strengthen the free electron resonance, increase the electric field strength of the surface plasmon resonance coupling, and greatly improve the detection sensitivity of the optical fiber SPR sensor 10 .

[0060] Optionally, the monosulfide layer can be in the form of MX, wherein M can be Ge or Sn, and X can be S, Se or Te, that is, the monosulfide layer can be any one of GeS, GeSe, GeTe, SnS, SnSe or SnTe, which can achieve the effect of the present application and will not be repeated here.

[0061] In a feasible implementation, the germanium sulfide film 13 has a thickness of 5 nm to 20 nm.

[0062] Among them, in the present application, the thickness of the germanium sulfide film 13 is 5nm to 20nm. When the thickness of the germanium sulfide film 13 is less than 5nm, the carrier mobility is low, and the effect of improving the sensitivity of the optical fiber SPR sensor 10 is not obvious; when the thickness of the germanium sulfide film 13 exceeds 20nm, the thickness is too high, resulting in a shallower resonance trough, a lower signal-to-noise ratio, and a decrease in the detection performance of the optical fiber SPR sensor 10. Optionally, when the thickness of the germanium sulfide film 13 is 10nm, the detection performance of the optical fiber SPR sensor 10 prepared is significantly improved.

[0063] In a feasible implementation, the optical fiber SPR sensor 10 includes two connectors 14 , namely a first connector and a second connector. The first connector is connected to the halogen light source 30 , and the second connector is connected to the spectrometer 40 .

[0064] The optical fiber SPR sensor 10 is placed in the solution to be tested 20, and the halogen light source 30 emits a spectrum. The light enters from the first connector of the optical fiber SPR sensor 10 and is transmitted to the second connector along the multimode optical fiber 11. The second connector of the optical fiber SPR sensor 10 is connected to the spectrometer 40 for processing and analyzing the transmitted optical signal.

[0065] Figure 3 It is a schematic diagram of a detection system based on an optical fiber SPR sensor according to an embodiment of the utility model.

[0066] like Figure 3 As shown, another embodiment of the utility model provides a detection system based on an optical fiber SPR sensor, the detection system comprising:

[0067] As in the above-mentioned embodiment, the optical fiber SPR sensor 10 is disposed in a solution 20 to be tested;

[0068] A halogen light source 30 is connected to the first connector of the optical fiber SPR sensor 10;

[0069] The spectrometer 40 has an input end connected to the second connector of the optical fiber SPR sensor 10 , and an output end connected to the remote terminal 50 .

[0070] Among them, the first connector of the optical fiber SPR sensor 10 is connected to the halogen light source 30, and the second connector of the optical fiber SPR sensor 10 is connected to the spectrometer 40. The optical fiber SPR sensor 10 is immersed in the solution to be tested 20. The halogen light source 30 can provide an emission spectrum with a wavelength within 360nm to 2400nm. The light enters from the first connector of the optical fiber SPR sensor 10 and is transmitted to the second connector along the multimode optical fiber 11. The second connector of the optical fiber SPR sensor 10 is connected to the spectrometer 40 for processing and analyzing the transmitted optical signal. The spectrometer 40 transmits the processed information to the remote terminal 50 through the data interface, that is, the output end, and records the acquired transmission spectrum in real time on the remote terminal 50. Due to the different concentrations of the solution to be tested 20, the corresponding solution refractive index is also different. According to the position offset of the resonant wavelength in the transmission spectrum, the concentration of the solution to be tested 20 can be obtained to achieve the purpose of biological molecule detection.

[0071] It should be noted that the remote terminal 50 is a desktop computer, a notebook or a tablet.

[0072] Specifically, light enters the multimode optical fiber 11 from the first connector of the optical fiber SPR sensor 10 and is transmitted in the fiber core. When the light is transmitted to the U-shaped portion of the optical fiber SPR sensor 10, a part of the light that does not meet the total reflection condition will be leaked into the cladding of the multimode optical fiber 11, and the other part continues to be transmitted in the multimode optical fiber 11. In the cladding, a part of the light meets the total reflection condition to produce an evanescent wave, and the evanescent wave produced can interact with the surrounding medium, and excites a surface plasma wave on the surface of the metal medium (metal film 12 and germanium sulfide film 13). When the two waves resonate, energy is transferred from photons to surface plasma, and most of the energy of the incident light is absorbed by the surface plasma wave, forming a resonance trough in the transmission spectrum. By recording the point of the resonance trough and the corresponding refractive index, the sensor sensitivity is obtained. Different concentrations correspond to different refractive indices, and the concentration change of the solution to be measured can be known.

[0073] Comparative Example

[0074] The optical fiber SPR sensor of the present application and the existing optical fiber SPR sensor with only gold film were immersed in five groups of solutions with different concentrations in turn. The refractive indices were measured by Abbe refractometer and were 1.33587, 1.34117, 1.35142, 1.36010 and 1.37527, respectively. The transmission spectra of the two sensors were recorded on a computer, and the measured transmission spectra were fitted to obtain the sensitivity and linearity of the optical fiber SPR sensor, which were compared and explained.

[0075] First, the optical fiber SPR sensor of the present application is immersed in five groups of solutions with different concentrations in turn, and the transmission spectra are recorded on a computer, such as Figure 4 The above results are linearly fitted to obtain a high-sensitivity fiber SPR sensor with a sensitivity of 7410.15nm / RIU and a linearity of 0.99506. Figure 5 shown.

[0076] The existing optical fiber SPR sensor with only gold film was immersed in five groups of solutions with different concentrations in turn, and the transmission spectra were recorded on a computer, such as Figure 6 The above results are linearly fitted to obtain the sensitivity of the gold film-based fiber SPR sensor to be 3455.72nm / RIU and the linearity to be 0.98389, as shown in Figure 7 shown.

[0077] It should be noted that the spectrum analysis software was used to record the different resonance spectrum curves corresponding to five groups of solutions with different refractive indices on a computer, and the five resonance wavelength points and the corresponding refractive indices were linearly fitted (origin software) to obtain the sensitivity fitting curve, where sensitivity = change in resonance wavelength / change in refractive index, which is the slope of the linear fitting curve. Figure 5 and Figure 7 In the figure, x is the refractive index and y is the wavelength. It can be seen that the R square of the fitting curve obtained by the origin software is close to 1, and the linear fitting effect is good. The optical fiber SPR sensor of the present application has a better fitting effect and thus has a better sensitivity.

[0078] By comparison, it can be seen that the sensitivity of the fiber optic SPR sensor of the present application can reach 7410.15nm / RIU, which is 2.14 times that of the existing fiber optic SPR sensor (3455.72nm / RIU). The sensitivity of this comparative example is calculated by the trough offset of the spectral curve, that is, for the same group of refractive index solutions (the corresponding five refractive indices are 1.33587, 1.34117, 1.35142, 1.36010 and 1.37527, respectively), the larger the trough offset, the higher the sensitivity of the sensor, such as Figure 4 and Figure 6 It can be seen that for the same set of refractive index solutions (corresponding to five refractive indices of 1.33587, 1.34117, 1.35142, 1.36010 and 1.37527, respectively), the spectral trough shift obtained by using the optical fiber SPR sensor of the present application is significantly greater than the spectral shift of the existing sensor. Therefore, the optical fiber SPR sensor provided by the present application significantly improves the sensitivity of the sensor and can achieve high-precision detection requirements.

[0079] In the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0080] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the present invention disclosed herein. The present invention is intended to cover any variation, use, or adaptation of the present invention that follows the general principles of the present invention and includes common knowledge or customary technical means in the art that are not disclosed in the present invention. The specification and examples are to be regarded as exemplary only.

[0081] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical fiber SPR sensor, characterized in that: The optical fiber SPR sensor comprises: Sensing matrix; A metal film is fixedly arranged outside the sensing substrate, and the metal film wraps the sensing substrate; The monosulfide layer is fixedly disposed outside the metal film.

2. The optical fiber SPR sensor according to claim 1, characterized in that: The sensing substrate is a multimode optical fiber with coating removed, and the length of the multimode optical fiber is 1.5 cm to 2.2 cm.

3. The optical fiber SPR sensor according to claim 2, characterized in that: The multimode optical fiber is U-shaped, and the curvature radius of the U-shaped multimode optical fiber is 0.5 mm to 2 mm.

4. The optical fiber SPR sensor according to claim 2, characterized in that: The multimode optical fiber with coating removed further comprises a cladding and a core arranged in the cladding, the diameter of the cladding is 120 μm to 130 μm, and the diameter of the core is 60 μm to 65 μm.

5. The optical fiber SPR sensor according to claim 1, characterized in that: The metal film is Au, Ag, Al or Cu, and the metal film is fixed on the sensing substrate by sputtering through an ion sputtering device.

6. The optical fiber SPR sensor according to claim 5, characterized in that: The thickness of the metal film is 50 nm.

7. The optical fiber SPR sensor according to claim 1, characterized in that: The single sulfide layer is a germanium sulfide film, and the germanium sulfide film is fixed outside the metal film by electrostatic self-assembly.

8. The optical fiber SPR sensor according to claim 7, characterized in that: The germanium sulfide film has a thickness of 5 nm to 20 nm.

9. The optical fiber SPR sensor according to claim 1, characterized in that: The optical fiber SPR sensor comprises two connectors, namely a first connector and a second connector, wherein the first connector is connected to a halogen light source, and the second connector is connected to a spectrometer.

10. A detection system based on an optical fiber SPR sensor, characterized in that: The detection system comprises: The optical fiber SPR sensor according to any one of claims 1 to 9, wherein the optical fiber SPR sensor is disposed in a solution to be tested; A halogen light source connected to the first connector of the optical fiber SPR sensor; A spectrometer, wherein the input end of the spectrometer is connected to the second connector of the optical fiber SPR sensor, and the output end of the spectrometer is connected to a remote terminal.

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