Biosensor with large detection range

Abstract

The utility model discloses a biosensor with a large detection range, which comprises an optical fiber body, a sensing area is formed on the optical fiber body, and a gold film layer and an indium gallium arsenic and gold nanoparticle film layer are respectively attached to the surface of the sensing area from inside to outside. According to the technical scheme, the surface electric field intensity of the gold film is improved by utilizing high carrier mobility and high light absorptivity of indium gallium arsenic, the sensitivity of the sensor is further improved, and an enhanced local electric field is generated between the indium gallium arsenic film and the gold nanoparticles by utilizing mutual coupling of surface plasmon polaritons of indium gallium arsenic and local plasmon polaritons generated by the gold nanoparticles, so that the sensitivity of the sensor is improved. The sensor structure provided by the technical scheme has relatively high sensing sensitivity and chemical stability, real-time monitoring can be realized, and the detection range of the biosensor is further expanded.

Description

Technical Field

[0001] This utility model relates to the field of biosensing technology, specifically a biosensor with a large detection range. Background Technology

[0002] Fiber optic SPR biosensors are biosensors based on the surface plasmon resonance (SPR) principle. They enable high sensitivity, high selectivity, and real-time monitoring of biomolecules, and are widely used in disease monitoring, drug development, and clinical diagnosis. Traditional biosensors detect biomolecules based on their interaction with physical or chemical methods (fluorescence / electrochemical principles). However, their limited sensitivity, susceptibility to interference, and the need for lengthy preparation and analysis processes have increasingly restricted their application in the field of biosensing.

[0003] SPR-based biosensors have received increasing attention in the field of biosensing in recent years due to their high sensitivity, good biocompatibility, flexible orientation, stability, and strong anti-interference ability.

[0004] However, current fiber optic SPR biosensors still have some problems. They are limited in detecting ultra-low concentrations of analytes and weak intermolecular interactions, and have the disadvantage of low sensitivity. Therefore, it is still necessary to improve the sensitivity and quality factor of SPR sensors. Utility Model Content

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a biosensor with a wide detection range, thus solving the aforementioned technical problems.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, this utility model provides the following technical solution: a biosensor with a large detection range, comprising an optical fiber body, a sensing region formed on the surface of the optical fiber body, and a gold film layer, an indium gallium arsenide film layer, and a gold nanoparticle film layer respectively attached to the surface of the sensing region from the inside to the outside. The optical fiber body includes a first multimode optical fiber, a single-mode optical fiber, and a second multimode optical fiber. The gold nanoparticle film layer is composed of gold nanoparticles. One end of the optical fiber body is connected to a broadband light source, and the other end of the optical fiber body is connected to a broadband spectrometer.

[0009] Preferably, one end of the single-mode fiber is connected to the first multimode fiber, and the other end of the single-mode fiber is connected to the second multimode fiber.

[0010] Preferably, the sensing area is formed at one end of the first multimode fiber near the single-mode fiber, and at one end of the single-mode fiber and the second multimode fiber near the single-mode fiber.

[0011] Preferably, the length of the single-mode optical fiber is 0.9cm-1.1cm;

[0012] The sensing area is formed on a first multimode fiber with a length of 0.4cm-0.6cm, a single-mode fiber with a length of 0.9cm-1cm, and a second multimode fiber with a length of 0.4cm-0.6cm, and the total length of the sensing area is 1.7cm-2.3cm.

[0013] Preferably, the length of the single-mode optical fiber is 1 cm;

[0014] The sensing area is formed by a 0.5cm long first multimode fiber, a 1cm long single-mode fiber, and a 0.5cm long second multimode fiber, with a total length of 2cm.

[0015] Preferably, the gold film layer is fixed on the sensing area by ion sputtering.

[0016] Preferably, the indium gallium arsenide film is fixed on the gold film by electrostatic self-assembly, and the thickness of the indium gallium arsenide film is 20 nm to 30 nm.

[0017] Preferably, the thickness of the indium gallium arsenide film is 25 nm.

[0018] Preferably, the gold film layer is fixed on the sensing area by ion sputtering, and the thickness of the gold film layer is 45nm to 55nm.

[0019] Preferably, the thickness of the gold film layer is 50 nm.

[0020] Compared with existing technologies, this utility model provides a biosensor with a large detection range and the following beneficial effects: The biosensor provided in this application includes an optical fiber body with a sensing region formed on it. A gold film layer, an indium gallium arsenide (IGaAs) film layer, and a gold nanoparticle film layer are respectively attached to the surface of the sensing region from the inside out. This technical solution utilizes the high carrier mobility and high light absorption of IGaAs to increase the electric field intensity on the gold film surface, thereby improving the sensor's sensitivity. It also utilizes the coupling between surface plasmon polaritons of IGaAs and localized plasmons generated by gold nanoparticles to generate an enhanced local electric field between the IGaAs film and the gold nanoparticles, thereby enhancing the interaction between surface plasmon waves and the analyte and improving detection sensitivity. The sensor structure provided by this technical solution has high sensing sensitivity and chemical stability, enabling real-time monitoring, thus improving the detection range of the biosensor. Attached Figure Description

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

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the connection structure of the optical fiber body, broadband light source and broadband spectrometer of this utility model;

[0024] Figure 4 This is a spectrum of the present invention used for measuring the absorption rate of a solution.

[0025] Figure 5 This is a graph showing the sensitivity of this invention compared with the quantitative performance of indium gallium arsenide thickness.

[0026] Among them: 100, optical fiber body; 200, broadband light source; 300, broadband spectrometer;

[0027] 110. Sensing area; 120. Gold film layer; 130. Indium gallium arsenide film layer; 140. Gold nanoparticle film layer;

[0028] 111. First multimode fiber; 112. Single-mode fiber; 113. Second multimode fiber. Detailed Implementation

[0029] The embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of this utility model.

[0030] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] Please see Figure 1-3 A biosensor with a wide detection range includes an optical fiber body, a sensing region formed on the surface of the optical fiber body, and a gold film layer, an indium gallium arsenide film layer and a gold nanoparticle film layer respectively attached to the surface of the sensing region from the inside to the outside. The optical fiber body includes a first multimode optical fiber, a single-mode optical fiber and a second multimode optical fiber. The gold nanoparticle film layer is composed of gold nanoparticles. One end of the optical fiber body is connected to a broadband light source and the other end of the optical fiber body is connected to a broadband spectrometer.

[0033] The biosensor provided in this application includes an optical fiber body with a sensing region formed on it. From the inside out, a gold film layer, an indium gallium arsenide (IGaAs) film layer, and a gold nanoparticle film layer are respectively attached to the surface of the sensing region. This technical solution utilizes the high carrier mobility and high light absorption of IGaAs to increase the electric field intensity on the gold film surface, thereby improving the sensor's sensitivity. It also utilizes the coupling between surface plasmon polaritons of IGaAs and localized plasmons generated by the gold nanoparticles to generate an enhanced local electric field between the IGaAs film and the gold nanoparticles, thereby enhancing the interaction between surface plasmon waves and the analyte and improving detection sensitivity. The sensor structure provided by this technical solution has high sensing sensitivity and chemical stability, enabling real-time monitoring and thus improving the detection range of the biosensor.

[0034] like Figure 1-2 As shown, the optical fiber body 100 includes: a first multimode optical fiber 111; a single-mode optical fiber 112, one end of which is connected to one end of the first multimode optical fiber 111; a second multimode optical fiber 113, the other end of which is connected to one end of the second multimode optical fiber 113; a sensing region 110 is formed at one end of the first multimode optical fiber 111 near the single-mode optical fiber 112, and at one end of the single-mode optical fiber 112 and the second multimode optical fiber 113 near the single-mode optical fiber 112; the length of the single-mode optical fiber 112 is 0.9cm-1.1cm; the sensing region 110 is formed on the first multimode optical fiber 111 with a length of 0.4cm-0.6cm, the single-mode optical fiber 112 with a length of 0.9cm-1cm, and the second multimode optical fiber 113 with a length of 0.4cm-0.6cm, and the total length of the sensing region 110 is 1.7cm-2.3cm.

[0035] In this technical solution, the sensing area 110 is formed by removing the outermost coating structure of the single-mode fiber 112 with fiber strippers to expose its cladding. After wiping the treated single-mode fiber 112 with a small amount of alcohol solution, a 0.9cm-1.1cm length of the single-mode fiber 112 is cut with a fiber optic cleaver. Then, the first multimode fiber 111 and the second multimode fiber 113 are cut. A 2cm-3cm length of the coating structure is removed from the end of each multimode fiber with fiber strippers to expose the cladding. After wiping the treated multimode fiber with a small amount of alcohol solution, the excess coating is removed from the end with a fiber optic cleaver, leaving a 0.4cm-0.6cm portion. Finally, the two sides of the single-mode fiber 112 are connected to the ends of the treated multimode fiber using a fiber optic fusion splicer. The sensor sensing area 110 is formed by removing the coating layer from the 0.4cm-0.6cm first multimode fiber 111, the 0.9cm-1.1cm single-mode fiber 112, and the 0.4cm-0.6cm second multimode fiber 113, resulting in a total length of 1.7cm-2.3cm for the sensing area 110.

[0036] In this technical solution, during the fabrication process, the length ratio of the first multimode fiber 111, the single-mode fiber 112, and the second multimode fiber 113 is 1:2:1. To facilitate the fabrication and application of the total length of the formed sensing region 110, the lengths of the multimode fiber and the single-mode fiber 112 (without the coating layer removed) are set accordingly. If the sensing region 110 is too long, it requires too much sample solution; if it is too short, it is inconvenient to fabricate and may affect the detection effect. Therefore, a length of 1.7cm-2.3cm for the sensing region 110 facilitates fabrication while meeting the detection requirements. A length of 2cm is optimal, in which case the length of the single-mode fiber 112 is 1cm. The sensing region 110 is formed from a 0.5cm long first multimode fiber 111, a 1cm long single-mode fiber 112, and a 0.5cm long second multimode fiber 113, resulting in a total length of 2cm for the sensing region 110.

[0037] In this technical solution, the thickness of the gold film layer is 45nm to 55nm. When the thickness of the gold film layer is too low, the generated local electric field strength is insufficient, which cannot meet the usage requirements, affects the sensitivity of the sensor, and is impractical to implement, making it impossible to obtain ideal results. At the same time, the thickness cannot be too high, as excessive thickness may lead to insufficient penetration of evanescent waves in the SPR resonance effect, a reduction in the interaction volume during wave vector matching, a shallower resonance depth, and a poorer anti-interference capability. When the thickness is between 45nm and 55nm, the usage requirements can be met.

[0038] Experiments have shown that when the thickness of the gold film layer is 50nm, the sensor has the highest quality factor, the strongest plasmon polariton intensity on the surface of the gold film layer, the best local electric field intensity, and the strongest excitation SPR.

[0039] The gold film layer is fixed onto the sensing area by ion sputtering. In this technical solution, the ion sputtering method is as follows:

[0040] The prepared fiber optic sensor was placed in a vacuum ion beam sputtering instrument, and a gold film was deposited on the sensor surface. Based on experience, the vacuum ion beam sputtering instrument has a current of 8mA and a time of 80 seconds. The thickness of the gold film is 50nm, and the thickness of the indium gallium arsenide film is 20nm to 30nm.

[0041] In this technical solution, when the thickness of the indium gallium arsenide (IGaAs) film is less than 20 nm, the carrier mobility and optical refractive index do not meet the requirements, resulting in low sensitivity. When the thickness of the IGaAs film is greater than 30 nm, the material loss also increases further, no obvious resonance trough is obtained, the signal-to-noise ratio decreases, the anti-disturbance ability deteriorates, and the quality factor is low, which also fails to meet the requirements. Therefore, an IGaAs film thickness of 25 nm is optimal.

[0042] In this technical solution, the best technical effect is achieved when the thickness of the indium gallium arsenide film is 25nm. When the thickness of the indium gallium arsenide film is 25nm, the carrier mobility and optical refractive index reach their peak values. The indium gallium arsenide film is fixed to the gold film by electrostatic self-assembly.

[0043] In this technical solution, the electrostatic self-assembly method is as follows:

[0044] Before coating the indium gallium arsenide (IGaAs) nanosheet dispersion, firstly, dilute with deionized water to obtain 50 ml of 4% glacial acetic acid solution. Weigh 500 mg of chitosan powder and add it to the glacial acetic acid solution, stirring continuously for 15 min until the chitosan is completely dissolved. Transfer 3 ml of the chitosan solution to a small beaker, and simultaneously add 3 ml of the IGaAs nanosheet dispersion to the chitosan solution. Then, treat the resulting mixture with ultrasound for 15 min to obtain a well-distributed IGaAs nanosheet dispersion. The resulting IGaAs dispersion exhibits positive charge characteristics.

[0045] PSS is a negatively charged anionic polymer that can bind with cationic polymers. The pre-sputtered gold film sensing area was immersed in a 5 mg / ml PSS solution for 2 minutes, followed by 10 minutes of air exposure. This process imparts a negative charge to the surface of the sensing area after the gold film has been sputtered, allowing for better adsorption of positively charged indium gallium arsenide nanosheets and the formation of a stable indium gallium arsenide nanofilm on the gold film.

[0046] The sensor, after being treated with PSS solution, was fixed on a lifting coating machine. A traction speed of 1500 μm / s and a traction length of 20 mm were set. Indium gallium arsenide nanosheets with positive charge properties treated with chitosan were coated on the sensing area for 20 / 30 / 40 cycles respectively. The thickness of the indium gallium arsenide nanofilm increased with the number of cycles. After coating, the sensor was left to stand in the air for 24 hours. The indium gallium arsenide film was then fixed on the surface of the gold film. The gold nanoparticle film was attached to the indium gallium arsenide film and was located on the side of the indium gallium arsenide film away from the tapered optical fiber body.

[0047] The specific method for coating the gold nanoparticle film is as follows: Before fixing the gold nanoparticles, the sensor coated with the indium gallium arsenide film is immersed in an ethanol solution of 2 mmol / L p-aminothiophenol for 24 hours, rinsed with distilled water, and dried. Then, the sensor is immersed in the gold nanoparticle dispersion for 12 hours and dried. After completion, the gold nanoparticles are fixed on the surface of the indium gallium arsenide film.

[0048] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A biosensor with a wide detection range, comprising an optical fiber body, characterized in that: A sensing region is formed on the surface of the optical fiber body. From the inside to the outside, the surface of the sensing region is coated with a gold film layer, an indium gallium arsenide film layer, and a gold nanoparticle film layer. The optical fiber body includes a first multimode optical fiber, a single-mode optical fiber, and a second multimode optical fiber. The gold nanoparticle film layer is composed of gold nanoparticles. One end of the optical fiber body is connected to a broadband light source, and the other end of the optical fiber body is connected to a broadband spectrometer.

2. A biosensor with a large detection range according to claim 1, characterized in that: One end of the single-mode fiber is connected to the first multimode fiber, and the other end of the single-mode fiber is connected to the second multimode fiber.

3. A biosensor with a large detection range according to claim 1, characterized in that: The sensing area is formed at one end of the first multimode fiber near the single-mode fiber, and at one end of the single-mode fiber and the second multimode fiber near the single-mode fiber.

4. A biosensor with a large detection range according to claim 1, characterized in that: The length of the single-mode optical fiber is 0.9cm-1.1cm; The sensing area is formed on a first multimode fiber with a length of 0.4cm-0.6cm, a single-mode fiber with a length of 0.9cm-1cm, and a second multimode fiber with a length of 0.4cm-0.6cm, and the total length of the sensing area is 1.7cm-2.3cm.

5. A biosensor with a large detection range according to claim 4, characterized in that: The length of the single-mode optical fiber is 1 cm; The sensing area is formed on a first multimode fiber with a length of 0.5cm, a single-mode fiber with a length of 1cm, and a second multimode fiber with a length of 0.5cm, and the total length of the sensing area is 2cm.

6. A biosensor with a large detection range according to claim 1, characterized in that: The gold film layer is fixed onto the sensing area by ion sputtering.

7. A biosensor with a large detection range according to claim 1, characterized in that: The indium gallium arsenide film is fixed on the gold film by electrostatic self-assembly, and the thickness of the indium gallium arsenide film is 20 nm to 30 nm.

8. A biosensor with a large detection range according to claim 7, characterized in that: The thickness of the indium gallium arsenide film is 25 nm.

9. A biosensor with a large detection range according to claim 1, characterized in that: The gold film layer is fixed on the sensing area by ion sputtering, and the thickness of the gold film layer is 45nm to 55nm.

10. A biosensor with a large detection range according to claim 9, characterized in that: The thickness of the gold film layer is 50 nm.

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