Probe-type copper ion sensor based on SPR

Abstract

The present invention relates to the field of sensor technology, and discloses a probe-type copper ion sensor based on SPR, comprising: a multimode optical fiber with an inner diameter of 105 μm and an outer diameter of 125 μm; a quartz capillary with an inner diameter of 30 μm, an outer diameter of 125 μm, and a length of 2 mm; a 50 nm thick gold film is plated on the outer surface of the quartz capillary; a 200 nm thick gold film is plated on the end face of the quartz capillary to form a reflective surface; and a 10 μm thick specific hydrogel film is coated on the outer surface of the quartz capillary. Through the surface plasmon resonance (SPR) technology, the sensor can achieve high-sensitivity detection of copper ions, and the detection limit can reach 3×10 ‑12 mol / L. Compared with traditional detection methods, the SPR-based probe copper ion sensor can detect lower concentrations of copper ions, thereby improving the accuracy of detection.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, in particular to a probe-type copper ion sensor based on SPR. Background Art

[0002] Copper (Cu2+) ion is one of the most important metal ions and plays a vital role in many applications with very important functions in nature and the human body. It plays an important role in the human body as a catalytic cofactor of redox-regulated enzymes, such as a variety of metalloenzymes, including tyrosinase, lysyl oxidase, cytochrome c oxidase, and superoxide dismutase. It is an indispensable catalyst in the absorption of iron and the synthesis of heme. Cu2+ ions have no toxic effects on the human body under normal circumstances; however, both excess and deficiency can cause various hazards. Although trace amounts of Cu2+ ions are sufficient to meet normal physiological processes, intake exceeding the daily required dose can have a negative impact on human health. Excessive intake of Cu2+ ions can cause symptoms such as diarrhea, vomiting, dizziness, and stomach pain. Free C accumulated in the body due to long-term exposure Cu2+ ions generate reactive oxygen species due to their redox activity and damage lipids, DNA and proteins. Free oxygen is potentially toxic to cells. Many diseases may develop in the body depending on the defects in hemostasis. Increasing the concentration of Cu2+ ions can lead to many adverse health problems, such as Wilson's disease, Parkinson's disease, Menkes disease, neurodegenerative diseases and Alzheimer's disease, as well as Huntington's disease and acute liver and kidney failure. Therefore, accurate detection of Cu2+ concentration is of great significance to many fields such as medical monitoring. Developing a low-consumption, high-efficiency and environmentally friendly detection method is also a goal that people have been pursuing. After the unremitting efforts of researchers, various methods for detecting Cu2+ have been proposed, such as fluorescence spectroscopy, electrochemical method, photothermal effect method, colorimetry and sensor method, which can effectively detect the concentration of copper ions.

[0003] However, these methods require more chemical reagents, are prone to pollution, have complicated experimental steps, long response time, and low sensitivity. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a probe-type copper ion sensor based on SPR, which solves the problem that the traditional copper ion detection technology has low sensitivity and cannot accurately detect the concentration of copper ions.

[0005] To achieve the above objectives, the present invention is implemented through the following technical scheme: a probe-type copper ion sensor based on SPR, comprising a multimode optical fiber, a quartz capillary, a hydrogel film, and a gold film, wherein the outer wall of the multimode optical fiber is provided with a quartz capillary, the outer surface of the quartz capillary is plated with a gold film with a thickness of 50 nm to form a metal coating, the end face of the quartz capillary is plated with a gold film with a thickness of 200 nm to form a reflecting surface, a specific hydrogel film with a thickness of 10 μm is coated on the outer surface of the quartz capillary, the inner diameter of the multimode optical fiber is 105 μm, the outer diameter is 125 μm, the inner diameter of the quartz capillary is 30 μm, the outer diameter is 125 μm, and the length is 2 mm, the hydrogel film is prepared by using N-vinyl imidazole as a functional monomer, acrylamide and N,N'-methylenebisacrylamide as cross-linking agents, and dihydrochloride as an ultraviolet initiator, and the hydrogel film can undergo a chelating reaction with copper ions in the inspection solution.

[0006] Preferably, the preparation method of the SPR-based probe-type copper ion sensor comprises the following specific steps:

[0007] S1: Preparation of multimode optical fiber: select a multimode optical fiber with an inner diameter of 105 μm and an outer diameter of 125 μm, use an ultrasonic cleaner to clean the multimode optical fiber to remove surface dirt and impurities, and dry the cleaned multimode optical fiber;

[0008] S2: Preparation of quartz capillary: select a quartz capillary with an inner diameter of 30 μm, an outer diameter of 125 μm, and a length of 2 mm, use chemical reagents to clean the inner and outer surfaces of the quartz capillary to ensure that the surface is clean, and dry the cleaned quartz capillary;

[0009] S3: Fusion of the sensor, connecting the processed multimode optical fiber and the quartz capillary to enable the optical signal to be effectively transmitted;

[0010] S4: Plating of gold film: in a vacuum coating device, a quartz capillary is placed on a coating table, and the coating device parameters are adjusted to coat a 50nm thick gold film on the outer surface of the quartz capillary so that the gold film evenly covers the entire surface. The end face of the quartz capillary is plated with a 200nm thick gold film to form a reflective surface. After the coating is completed, the quartz capillary is stored;

[0011] S5: Preparation of specific hydrogel film: weigh appropriate amounts of N-vinyl imidazole, acrylamide and N,N'-methylenebisacrylamide, mix them in a certain proportion, add an appropriate amount of dihydrochloride to the mixture as an ultraviolet initiator, and evenly coat the mixture on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, irradiate with an ultraviolet light source, perform curing treatment, and form a stable specific hydrogel film;

[0012] S6: Sensor testing: Place the assembled sensor in a container containing copper ion solutions of different concentrations, input the optical signal through a multimode optical fiber, record the transmission spectrum output by the sensor, analyze the position of the resonance absorption peak in the transmission spectrum, and calculate the copper ion concentration.

[0013] Preferably, in the step S1, the multimode optical fiber is cleaned with ethanol at 20°C for 5 minutes using an ultrasonic cleaner to remove surface dirt and impurities, the cleaned multimode optical fiber is rinsed with deionized water 3 times for 1 minute each time, and the cleaned multimode optical fiber is placed in an oven at 60°C to dry for 2 hours.

[0014] Preferably, in the step S2, the quartz capillary is immersed in a 10% hydrofluoric acid solution at room temperature for 30 minutes for surface activation treatment, the quartz capillary is rinsed 5 times with deionized water for 2 minutes each time, and the cleaned quartz capillary is placed in an oven at 60°C and dried for 2 hours.

[0015] Preferably, in the step S4, at 10 -5 In a vacuum environment of 0.03 Pa, a 50 nm thick gold film was plated on the outer surface of the quartz capillary by electron beam evaporation, so that the gold film evenly covered the entire surface. The end face of the quartz capillary was plated using the same method.

[0016] Preferably, in the step S5, 10 g of N-vinyl imidazole, 20 g of acrylamide and 0.5 g of N,N'-methylenebisacrylamide are weighed and mixed in proportion, 0.1 g of dihydrochloride is added to the mixture as an ultraviolet initiator, and the mixture is evenly coated on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, which is irradiated with a 365 nm ultraviolet light source for 30 minutes.

[0017] Preferably, in step S6, the assembled sensor is placed in a solution containing copper ions of different concentrations, ranging from 1×10 -12 mol / L to 1×10 -5 mol / L container, and input an optical signal with a wavelength of 650nm through a multimode optical fiber.

[0018] Preferably, the method for using the SPR-based probe-type copper ion sensor comprises the following specific steps:

[0019] S1: Take an appropriate amount of water sample to be tested, place it in a clean container, place the water sample in a constant temperature environment, stir to make the solution uniform, and then adjust the temperature and pH value of the water sample to meet the test requirements;

[0020] S2: Preparation and calibration of the sensor: the SPR-based probe copper ion sensor is connected to the light source and the detection equipment to perform preliminary calibration of the sensor, observe whether the equipment works normally, and calibrate the sensitivity and accuracy of the sensor by detecting a copper ion solution of known concentration;

[0021] S3: Insert the SPR-based probe copper ion sensor into the water sample to be tested, so that the water sample fully contacts the hydrogel film on the sensor surface, input the light signal to the sensor through the multimode optical fiber, record the transmission spectrum output by the sensor, calculate the concentration of copper ions in the water sample by analyzing the position of the resonance absorption peak in the transmission spectrum, record the test results, and compare them with standard samples of known concentration to verify the accuracy of the test.

[0022] Preferably, in step S1, 10 ml of water to be tested is taken and placed in a clean glass container, the pH value of the water sample is adjusted to 7.0 using a standard buffer solution so that the copper ions are in a stable state in the solution, the water sample is placed in a constant temperature environment of 25°C, and the SPR-based probe copper ion sensor is connected to a light source and a detection device to measure the known concentration of 1×10 - 9 mol / L、1×10 -8 mol / L and 1×10 -7 mol / L copper ion solution, calibrate the sensitivity and accuracy of the sensor, record the transmission spectrum and corresponding copper ion concentration of each calibration, and establish a calibration curve.

[0023] Preferably, in the step S3, a light signal with a wavelength of 650 nm is input to the sensor through a multimode optical fiber, and the transmission spectrum output by the sensor is recorded. The same water sample is tested multiple times, once every 5 minutes, for a total of 5 times, the test results are recorded and the average value is calculated.

[0024] The present invention provides a probe-type copper ion sensor based on SPR, which has the following beneficial effects:

[0025] 1. The present invention uses surface plasmon resonance (SPR) technology to achieve high-sensitivity detection of copper ions, with a detection limit of 3×10 -12 mol / L. Compared with traditional detection methods, the SPR-based probe copper ion sensor can detect lower concentrations of copper ions, thereby improving the accuracy of detection.

[0026] 2. The present invention can undergo a chelation reaction with copper ions through the specific hydrogel film on the surface of the sensor, which has high selectivity and specificity, thus effectively avoiding interference from other ions, thereby achieving the effect of improving the accuracy of copper ion detection.

[0027] 3. The sensor of the present invention has a compact design structure and small size, and is suitable for rapid on-site detection. Its small size enables it to be measured in a small space, expanding the application scenarios, thereby achieving the effect of being easy to carry and operate.

[0028] 4. The present invention adopts optical detection technology through the sensor, which can effectively avoid the influence of electromagnetic interference, so that accurate detection results can be obtained in complex electromagnetic environments.

[0029] 5. The sensor of the present invention adopts quartz capillary and gold film materials. These materials have good corrosion resistance and can work for a long time in a corrosive environment. They are suitable for various industrial and environmental monitoring scenarios, thereby achieving the effect of making the sensor have high corrosion resistance.

[0030] 6. The present invention takes long-term stability into consideration in the design and material selection of the sensor. Its structural design and material selection enable it to have high stability and good repeatability during repeated measurements, thereby ensuring that the sensor can be used for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a three-dimensional diagram of the probe type copper ion sensor of the present invention;

[0032] Figure 2 The figure is a schematic flow chart of a method for preparing a probe-type copper ion sensor based on SPR of the present invention;

[0033] Figure 3 The present invention is a schematic flow chart of a method for using the SPR-based probe copper ion sensor.

[0034] Among them, 1. multimode optical fiber; 2. quartz capillary; 3. hydrogel film; 4. gold film. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Please see attached Figure 1 - Attachment Figure 3The embodiment of the present invention provides a probe-type copper ion sensor based on SPR, comprising a multimode optical fiber 1, a quartz capillary 2, a hydrogel film 3, and a gold film 4. The outer wall of the multimode optical fiber 1 is provided with a quartz capillary 2, the outer surface of the quartz capillary 2 is plated with a layer of gold film 4 with a thickness of 50 nm to form a metal coating, the end face of the quartz capillary 2 is plated with a layer of gold film 4 with a thickness of 200 nm to form a reflection surface, and a specific hydrogel film 3 with a thickness of 10 μm is coated on the outer surface of the quartz capillary 2. The inner diameter of the multimode optical fiber 1 is 105 μm, the outer diameter is 125 μm, the inner diameter of the quartz capillary 2 is 30 μm, the outer diameter is 125 μm, and the length is 2 mm. The hydrogel film 3 is prepared by using N-vinylimidazole as a functional monomer, acrylamide and N,N'-methylenebisacrylamide as cross-linking agents, and dihydrochloride as an ultraviolet initiator. The hydrogel film 3 can undergo a chelating reaction with copper ions in the inspection solution;

[0037] Specifically, the multimode optical fiber is used to transmit the optical signal emitted by the light source to the probe part of the sensor. The multimode optical fiber can support the transmission of multiple optical modes, so that the loss during the optical transmission process is small, ensuring that sufficient optical signals reach the detection area of ​​the sensor. The structure of the multimode optical fiber can reduce the attenuation and scattering of the optical signal during the transmission process, and improve the stability and transmission efficiency of the optical signal; the quartz capillary plays the role of optical signal coupling in the sensor. The optical signal is transmitted to the quartz capillary through the multimode optical fiber, and is coupled to the cladding mode through the quartz capillary to achieve effective conduction of the optical signal. The quartz capillary provides a stable structural platform for supporting and fixing the gold film and the hydrogel film, ensuring the overall mechanical stability of the sensor; the gold film is used on the surface of the quartz capillary to excite the surface Surface plasmon resonance, surface plasmon resonance is a resonance phenomenon caused by the interaction between electrons on the metal surface and incident light, which is characterized by strong absorption and reflection of specific wavelengths of light; the gold film can enhance the local electric field strength of the light signal on the sensor surface, improve the sensitivity of the sensor to environmental changes, and thus improve the accuracy of detecting copper ion concentration; the hydrogel film can undergo a chelation reaction with copper ions in the solution, specifically capture and identify copper ions, and the hydrogel film will change its refractive index after combining with copper ions. The change in refractive index can be detected through the SPR phenomenon, thereby realizing the measurement of copper ion concentration. The hydrogel film can significantly improve the sensor's detection sensitivity and selectivity for copper ions, ensuring that copper ions can still be accurately detected in a low concentration environment.

[0038] The preparation method of the SPR-based probe-type copper ion sensor comprises the following specific steps:

[0039] S1: Preparation of multimode optical fiber: select a multimode optical fiber with an inner diameter of 105 μm and an outer diameter of 125 μm, use an ultrasonic cleaner to clean the multimode optical fiber to remove surface dirt and impurities, and dry the cleaned multimode optical fiber;

[0040] S2: Preparation of quartz capillary: select a quartz capillary with an inner diameter of 30 μm, an outer diameter of 125 μm, and a length of 2 mm, use chemical reagents to clean the inner and outer surfaces of the quartz capillary to ensure that the surface is clean, and dry the cleaned quartz capillary;

[0041] S3: Fusion of the sensor, connecting the processed multimode optical fiber and the quartz capillary to enable the optical signal to be effectively transmitted;

[0042] S4: Plating of gold film: in a vacuum coating device, a quartz capillary is placed on a coating table, and the coating device parameters are adjusted to coat a 50nm thick gold film on the outer surface of the quartz capillary so that the gold film evenly covers the entire surface. The end face of the quartz capillary is plated with a 200nm thick gold film to form a reflective surface. After the coating is completed, the quartz capillary is stored;

[0043] S5: Preparation of specific hydrogel film: weigh appropriate amounts of N-vinyl imidazole, acrylamide and N,N'-methylenebisacrylamide, mix them in a certain proportion, add an appropriate amount of dihydrochloride to the mixture as an ultraviolet initiator, and evenly coat the mixture on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, irradiate with an ultraviolet light source, perform curing treatment, and form a stable specific hydrogel film;

[0044] S6: Sensor testing: Place the assembled sensor in a container containing copper ion solutions of different concentrations, input the optical signal through a multimode optical fiber, record the transmission spectrum output by the sensor, analyze the position of the resonance absorption peak in the transmission spectrum, and calculate the copper ion concentration.

[0045] In step S1, the multimode optical fiber is cleaned with ethanol at 20° C. for 5 minutes using an ultrasonic cleaner to remove surface dirt and impurities, and the cleaned multimode optical fiber is rinsed with deionized water 3 times for 1 minute each time, and the cleaned multimode optical fiber is placed in an oven at 60° C. to dry for 2 hours.

[0046] In step S2, the quartz capillary was immersed in 10% hydrofluoric acid solution at room temperature for 30 minutes for surface activation treatment, and the quartz capillary was rinsed 5 times with deionized water for 2 minutes each time. The cleaned quartz capillary was placed in an oven at 60°C and dried for 2 hours.

[0047] In step S4, at 10 -5 In a vacuum environment of 0.03 Pa, a 50 nm thick gold film was plated on the outer surface of the quartz capillary by electron beam evaporation, so that the gold film evenly covered the entire surface. The end face of the quartz capillary was plated using the same method.

[0048] In step S5, 10 g of N-vinyl imidazole, 20 g of acrylamide and 0.5 g of N,N'-methylenebisacrylamide were weighed and mixed in proportion, 0.1 g of dihydrochloride was added to the mixture as an ultraviolet initiator, and the mixture was evenly coated on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, which was irradiated with a 365 nm ultraviolet light source for 30 minutes.

[0049] In step S6, the assembled sensor was placed in solutions containing different concentrations of copper ions, ranging from 1×10 -12 mol / L to 1×10 -5 mol / L container, an optical signal with a wavelength of 650 nm is input through a multimode optical fiber;

[0050] Specifically, after testing, the detection limit of the sensor can reach 3×10 -12 mol / L, and has good linear response in the range of 0.01 to 10ppm.

[0051] The method for using the SPR-based probe copper ion sensor includes the following specific steps:

[0052] S1: Take an appropriate amount of water sample to be tested, place it in a clean container, place the water sample in a constant temperature environment, stir to make the solution uniform, and then adjust the temperature and pH value of the water sample to meet the test requirements;

[0053] S2: Preparation and calibration of the sensor: the SPR-based probe copper ion sensor is connected to the light source and the detection equipment to perform preliminary calibration of the sensor, observe whether the equipment works normally, and calibrate the sensitivity and accuracy of the sensor by detecting a copper ion solution of known concentration;

[0054] S3: Insert the SPR-based probe copper ion sensor into the water sample to be tested, so that the water sample fully contacts the hydrogel film on the sensor surface, input the light signal to the sensor through the multimode optical fiber, record the transmission spectrum output by the sensor, calculate the concentration of copper ions in the water sample by analyzing the position of the resonance absorption peak in the transmission spectrum, record the test results, and compare them with standard samples of known concentration to verify the accuracy of the test.

[0055] In step S1, 10 ml of water to be tested was taken and placed in a clean glass container. The pH value of the water sample was adjusted to 7.0 using a standard buffer solution to stabilize the copper ions in the solution. The water sample was placed in a constant temperature environment at 25 °C. The SPR-based probe copper ion sensor was connected to a light source and a detection device to measure the known concentration of 1×10 -9 mol / L、1×10 -8 mol / L and 1×10 -7mol / L copper ion solution, calibrate the sensitivity and accuracy of the sensor, record the transmission spectrum and corresponding copper ion concentration of each calibration, and establish a calibration curve.

[0056] In step S3, a light signal with a wavelength of 650 nm is input to the sensor through a multimode optical fiber, and the transmission spectrum output by the sensor is recorded. The same water sample is tested multiple times, once every 5 minutes, for a total of 5 times, and the test results are recorded and the average value is calculated;

[0057] Specifically, after actual application tests, the sensor can effectively detect low concentrations of copper ions, and the detection results in different water samples are consistent, proving its reliability and stability in actual environments.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A copper ion detection method based on a probe-type copper ion sensor of SPR, characterized in that: The SPR-based probe-type copper ion sensor comprises: A multimode optical fiber (1) having an inner diameter of 105 μm and an outer diameter of 125 μm, and used for transmitting the optical signal emitted by the light source to the probe part of the sensor. The multimode optical fiber can support the transmission of multiple optical modes, so that the loss during the optical transmission process is small, ensuring that sufficient optical signals reach the detection area of ​​the sensor; A quartz capillary (2) having an inner diameter of 30 μm, an outer diameter of 125 μm and a length of 2 mm. The quartz capillary is butt-jointed with the multimode optical fiber. The quartz capillary plays a role in coupling optical signals in the sensor. The optical signal is transmitted to the quartz capillary through the multimode optical fiber and is coupled to the cladding mode by the multimode optical fiber, thereby achieving effective conduction of the optical signal. The outer surface of the quartz capillary (2) is plated with a layer of gold film (4) with a thickness of 50 nm. The gold film on the surface of the quartz capillary is used to excite surface plasma resonance, which can enhance the local electric field intensity of the optical signal on the sensor surface; The end surface of the quartz capillary (2) is plated with a gold film (4) with a thickness of 200 nm to form a reflective surface; The outer surface of the quartz capillary (2) is coated with a specific hydrogel film (3) with a thickness of 10 μm, wherein the hydrogel film is prepared by using N-vinyl imidazole as a functional monomer, acrylamide and N,N'-methylenebisacrylamide as crosslinking agents, and dihydrochloride as an ultraviolet initiator; the hydrogel film can undergo a chelating reaction with copper ions in the solution to specifically capture and identify copper ions. After the hydrogel film combines with copper ions, its refractive index will change, and the change in refractive index can be detected by the SPR phenomenon, thereby realizing the measurement of copper ion concentration; The copper ion detection method comprises the following specific steps: Step 1: Take an appropriate amount of water sample to be tested, place it in a clean container, place the water sample in a constant temperature environment, stir to make the solution uniform, and then adjust the temperature and pH value of the water sample to meet the detection requirements; wherein, take 10ml of the water to be tested, place it in a clean glass container, and use a standard buffer solution to adjust the pH value of the water sample to 7.0, so that the copper ions are in a stable state in the solution; Step 2: Preparation and calibration of the sensor: Connect the SPR-based probe copper ion sensor to the light source and detection equipment, perform preliminary calibration of the sensor, observe whether the equipment works properly, and calibrate the sensitivity and accuracy of the sensor by detecting a copper ion solution of known concentration; Step three: insert the SPR-based probe copper ion sensor into the water sample to be tested, so that the water sample fully contacts the hydrogel film on the surface of the sensor, input the light signal to the sensor through the multimode optical fiber, record the transmission spectrum output by the sensor, calculate the concentration of copper ions in the water sample by analyzing the position of the resonance absorption peak in the transmission spectrum, record the test results, and compare them with the standard samples of known concentration to verify the accuracy of the test; wherein, input the light signal with a wavelength of 650nm to the sensor through the multimode optical fiber, record the transmission spectrum output by the sensor, perform multiple tests on the same water sample, once every 5 minutes, for a total of 5 times, record the test results and calculate the average value.

2. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 1, characterized in that: The preparation steps of the SPR-based probe copper ion sensor are as follows: S1: Preparation of multimode optical fiber: select a multimode optical fiber with an inner diameter of 105 μm and an outer diameter of 125 μm, use an ultrasonic cleaner to clean the multimode optical fiber to remove surface dirt and impurities, and dry the cleaned multimode optical fiber; S2: Preparation of quartz capillary: select a quartz capillary with an inner diameter of 30 μm, an outer diameter of 125 μm, and a length of 2 mm, use chemical reagents to clean the inner and outer surfaces of the quartz capillary to ensure that the surface is clean, and dry the cleaned quartz capillary; S3: Fusion of the sensor, connecting the processed multimode optical fiber and the quartz capillary to enable the optical signal to be effectively transmitted; S4: Plating of gold film: in a vacuum coating device, a quartz capillary is placed on a coating table, and the coating device parameters are adjusted to coat a 50nm thick gold film on the outer surface of the quartz capillary so that the gold film evenly covers the entire surface. The end face of the quartz capillary is plated with a 200nm thick gold film to form a reflective surface. After the coating is completed, the quartz capillary is stored; S5: Preparation of specific hydrogel film: weigh appropriate amounts of N-vinyl imidazole, acrylamide and N,N'-methylenebisacrylamide, mix them in a certain proportion, add an appropriate amount of dihydrochloride to the mixture as an ultraviolet initiator, and evenly coat the mixture on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, irradiate with an ultraviolet light source, perform curing treatment, and form a stable specific hydrogel film; S6: Sensor testing: Place the assembled sensor in a container containing copper ion solutions of different concentrations, input the optical signal through a multimode optical fiber, record the transmission spectrum output by the sensor, analyze the position of the resonance absorption peak in the transmission spectrum, and calculate the copper ion concentration.

3. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 2, characterized in that: In the step S1, the multimode optical fiber is cleaned with ethanol at 20° C. for 5 minutes using an ultrasonic cleaner to remove surface dirt and impurities, the cleaned multimode optical fiber is rinsed with deionized water 3 times, each time for 1 minute, and the cleaned multimode optical fiber is placed in an oven at 60° C. to dry for 2 hours.

4. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 2, characterized in that: In the step S2, the quartz capillary is immersed in a 10% hydrofluoric acid solution at room temperature for 30 minutes for surface activation treatment, the quartz capillary is rinsed 5 times with deionized water for 2 minutes each time, and the cleaned quartz capillary is placed in an oven at 60° C. and dried for 2 hours.

5. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 2, characterized in that: In the step S4, at 10 -5 In a vacuum environment of 0.03 Pa, a 50 nm thick gold film was plated on the outer surface of the quartz capillary by electron beam evaporation, so that the gold film evenly covered the entire surface. The end face of the quartz capillary was plated using the same method.

6. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 2, characterized in that: In the step S5, 10 g of N-vinyl imidazole, 20 g of acrylamide and 0.5 g of N,N'-methylenebisacrylamide were weighed and mixed in proportion, 0.1 g of dihydrochloride was added to the mixture as an ultraviolet initiator, and the mixture was evenly coated on the outer surface of the quartz capillary to form a 10 μm thick hydrogel film, which was irradiated with a 365 nm ultraviolet light source for 30 minutes.

7. The copper ion detection method of the SPR-based probe copper ion sensor according to claim 2, characterized in that: In step S6, the assembled sensor is placed in solutions containing copper ions of different concentrations, ranging from 1×10 -12 mol / L to 1×10 -5 mol / L container, and input an optical signal with a wavelength of 650nm through a multimode optical fiber.

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