A preparation method for LPFG for detecting pH value

Abstract

The present invention provides a preparation method of LPFG for detecting pH value, which belongs to the field of long period fiber grating detection technology. The specific method is to first assemble sodium polystyrene sulfonate and titanium dioxide film on the surface of long period grating, modulate LPFG to make it in the best refractive index sensitivity area, and then further assemble hyaluronic acid and polyallylamine hydrochloride film on the surface of LPFG to obtain LPFG with good response to pH value. The modification of this nano film greatly improves the ability of LPFG to distinguish and identify different pH values, and will play a unique advantage in pH value detection in harsh environments, especially in environments that are not easy for humans to touch and operate, and is expected to be applied in many fields such as environment, bioengineering, chemistry and clinical practice.

Description

Technical Field

[0001] The present invention belongs to the technical field of long period fiber grating detection, and specifically relates to a method for preparing LPFG for detecting pH value. Background Art

[0002] pH value is one of the important physical and chemical parameters of aqueous solution and the most important water chemistry test index. All natural phenomena, chemical changes and production processes involving aqueous solution are related to pH value. pH value measurement is required in many fields such as industry, agriculture, medicine, environmental protection and scientific research. For example, meat pH test can be used to determine the shelf life and properties of meat; by measuring the pH value of urine, it can be determined whether the human body has an acidification tendency; in the water treatment process, the clarification and disinfection process can be optimized by controlling pH; the water distribution system can minimize its corrosion to the pipe network by controlling pH; by testing the pH value of paper, the quality of printed products can be predicted and the pH value of the fountain solution can be adjusted. Therefore, the detection of pH value is of great significance.

[0003] Long period fiber grating (LPFG) is a typical passive optical sensor device that is sensitive to environmental changes. In addition to the advantages of small size, anti-electromagnetic interference, and long-distance signal transmission, it is also sensitive to the surrounding environment. Therefore, in recent years, long period fiber grating has received widespread attention and has been widely used in fiber-optic communications and fiber-optic sensing systems. For example, "Optoelectronics & Laser" 2021.32(08) published "LPFG and coreless fiber cascaded refractive index and temperature simultaneous measurement sensor", co-authored by Tao Wuqiang, Jiang Chao, etc., which used long-period fiber grating for simultaneous measurement of refractive index and temperature; "Piezoelectrics & Acoustooptics" 2021 published "Long-period fiber grating glucose sensor for human body environment", co-authored by Zhang Shiyi, Jiang Chao, etc., which used long-period fiber grating for strain bending detection; "Acta Optica Sinica" 2020,40(18) published "Graphene oxide coated gold nanoshell modified long-period grating immunosensor", co-authored by Shi Shenghui, Wu Decao, etc., which used long-period fiber grating for avian influenza virus detection; "Optics Communications" 2004.229(1-6) published "Measurements of refractive index sensitivity using long-period fiber grating for simultaneous measurement of refractive index and temperature", co-authored by Joo Hin Chong, Ping Shum, etc. gratingrefractometer", which uses long-period fiber grating to measure the concentration of ethylene glycol, sucrose, and salt (9.09%-23.08%).

[0004] Long period grating is resistant to acid and alkali corrosion. If it is used to detect the pH value of a solution, it will play a unique advantage in harsh environments, especially in environments that are difficult for humans to touch and operate. However, bare long period gratings are usually insensitive to changes in pH and it is difficult to distinguish solutions with different pH values. Therefore, it is necessary to find a new method for long period grating to detect pH. Summary of the invention

[0005] In view of this, the present invention provides a preparation method for LPFG for detecting pH value, which has low operating cost and does not require harsh conditions and can be operated under room temperature and normal pressure.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing LPFG for detecting pH value comprises the following steps:

[0008] (1) preparing a polydiallyldimethylammonium chloride solution, a sodium polystyrene sulfonate solution, a titanium dioxide solution, a hyaluronic acid solution and a polyallylamine hydrochloride solution respectively and setting them aside;

[0009] (2) straightening the long period grating LPFG and fixing it in a liquid pool with a clamp;

[0010] (3) Cleaning the long-period grating area;

[0011] (4) adding a polydiallyldimethylammonium chloride solution into the liquid pool, and assembling a polydiallyldimethylammonium chloride film on the surface of the long period grating region;

[0012] (5) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen;

[0013] (6) adding a sodium polystyrene sulfonate solution into the liquid pool, and assembling a sodium polystyrene sulfonate film on the surface of the long period grating region;

[0014] (7) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen;

[0015] (8) adding a titanium dioxide solution into the liquid pool, and assembling a titanium dioxide film on the surface of the long period grating region;

[0016] (9) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen;

[0017] (10) Repeat the steps (6) to (9) until the long-period grating is in the optimal refractive index sensitive area;

[0018] (11) adding the hyaluronic acid solution into the liquid pool, and continuing to assemble the hyaluronic acid film on the surface of the titanium dioxide film in the long period grating region;

[0019] (12) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen gas;

[0020] (13) adding the hyaluronic acid solution into the liquid pool, and assembling a polyallylamine hydrochloride film on the surface of the long period grating region;

[0021] (14) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen gas;

[0022] (15) Repeat the steps (11) to (14) to assemble the required number of layers to obtain a long-period grating that can be used to detect pH value.

[0023] Preferably, it is characterized in that the polydiallyldimethylammonium chloride solution is prepared by the following method: dissolving polydiallyldimethylammonium chloride in water, then adding sodium chloride and stirring evenly to obtain the polydiallyldimethylammonium chloride solution; the molar concentration ratio of the polydiallyldimethylammonium chloride to sodium chloride is in the range of 1:0.001-30000.

[0024] Preferably, the sodium polystyrene sulfonate solution is prepared by the following method: dissolving sodium polystyrene sulfonate in water, then adding sodium chloride and stirring evenly to obtain the sodium polystyrene sulfonate solution; the molar concentration ratio of the sodium polystyrene sulfonate to the sodium chloride is in the range of 1:0.001-30000.

[0025] Preferably, the concentration of the titanium dioxide solution is 0.0001 mg / mL-10 g / mL; the pH of the titanium dioxide solution is 2.8-5.8; and the particle size of titanium dioxide in the titanium dioxide solution is 0.001-500 μm.

[0026] Preferably, the concentrations of the hyaluronic acid solution and the polyallylamine hydrochloride solution are both 0.0001-0.1 mol / L, and the pH values ​​are both 3-10.

[0027] Preferably, the hyaluronic acid solution and the polyallylamine hydrochloride solution both contain sodium chloride at a concentration of 0-0.3 mol / L.

[0028] Preferably, the assembling on the surface of the long-period grating region in steps (4), (6), (8), (11) and (13) is specifically performed on the surface of the long-period grating region cladding after being straightened and fixed.

[0029] Preferably, the time for assembling on the surface of the long-period grating region in steps (4), (6), (8), (11) and (13) is 1-30 minutes.

[0030] Preferably, the detection range of the pH value of the long period grating described in step (15) is 3 to 10.

[0031] In the present invention, the long period grating being in the optimal refractive index sensitive region means that the resonance wavelength has a very large shift when assembling a double-layer film.

[0032] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The long period grating prepared by the present invention improves the ability of LPFG to distinguish and identify different pH values;

[0034] 2. The long-period grating prepared by the present invention has the advantages of immunity to electromagnetic fields, tolerance to harsh environments, safety of in vivo pH measurement, and long-distance sensing capability. It will play a unique advantage in pH value detection in harsh environments, especially in environments that are difficult for humans to touch and operate;

[0035] 3. The long-period grating prepared by the present invention can be used for pH measurement of solutions in power plants, chemical industry, fermentation industry, food, metallurgy, pharmaceuticals, environmental protection, biochemistry and tap water industries, and is expected to be promoted and applied in the fields of environment, bioengineering, chemistry and clinical practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0037] Figure 1 It is a cross-sectional schematic diagram of the LPFG fixing device in the present invention.

[0038] Among them, in the figure:

[0039] 1-Long period grating fixing bracket; 2-Liquid pool; 3-Long period grating grating area; 4-Fixing device screws; 5-Optical fiber. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments 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.

[0041] Example 1

[0042] The long period grating LPFG is straightened and fixed in a liquid pool with a clamp, and then the long period grating region is cleaned, and a polydiallyldimethylammonium chloride film is further assembled on the surface of the long period grating region, and the long period grating region is fully rinsed with distilled water, and blown dry with nitrogen; then a sodium polystyrene sulfonate film is assembled on the surface of the long period grating region, and the long period grating region is fully rinsed with distilled water, and blown dry with nitrogen; then a titanium dioxide film is assembled on the surface of the long period grating region, and the long period grating region is fully rinsed with distilled water, and blown dry with nitrogen; the operating steps of assembling the sodium polystyrene sulfonate / titanium dioxide film are repeated until the long period grating is in the optimal refractive index sensitive area. Continue to assemble the hyaluronic acid film on the surface of the titanium dioxide film in the long-period grating area, rinse the long-period grating area thoroughly with distilled water, and blow dry with nitrogen; then assemble the polyallylamine hydrochloride film on the surface of the long-period grating area, rinse the long-period grating area thoroughly with distilled water, and blow dry with nitrogen; repeat the operating steps of assembling hyaluronic acid / polyallylamine hydrochloride until the required number of layers are assembled, and a long-period grating that can be used to detect pH value is obtained.

[0043] Example 2

[0044] 0.236g of polydiallyldimethylammonium chloride with a molecular weight of 100000 is dissolved in 100ml water, and then 5.844g of sodium chloride is added and stirred to obtain a polydiallyldimethylammonium chloride solution. 0.287g of sodium polystyrene sulfonate with a molecular weight of 100000 is dissolved in 100ml water, and then 5.844g of sodium chloride is added and stirred to obtain a sodium polystyrene sulfonate solution. 0.3g of titanium dioxide with a particle size of 300μm is dissolved in 300ml water, stirred to obtain a titanium dioxide solution. 18.71mg of polyallylamine hydrochloride is dissolved in 100ml water, and then 5.8mg of sodium chloride is added and stirred to obtain a polyallylamine hydrochloride solution. 80.66mg of hyaluronic acid is dissolved in 100ml water, and then 6mg of sodium chloride is added and stirred to obtain a hyaluronic acid solution. Add the prepared polydiallyldimethylammonium chloride solution to the reaction cell where the long period grating is fixed, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared sodium polystyrene sulfonate solution, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared titanium dioxide solution, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Repeat the above steps to add the sodium polystyrene sulfonate solution or the titanium dioxide solution in sequence, and assemble until the long period grating is in the best sensitive area to the refractive index. Then add the prepared hyaluronic acid solution, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared polyallylamine hydrochloride solution, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Repeat the above steps, alternately add the hyaluronic acid solution or the polyallylamine hydrochloride solution, assemble 20 layers of hyaluronic acid / polyallylamine hydrochloride nanofilms, and a long period grating with good response to pH is obtained.

[0045] Example 3

[0046] 0.118g of polydiallyldimethylammonium chloride with a molecular weight of 100000 is dissolved in 100ml water, then 1.461g of sodium chloride is added, and stirred to obtain polydiallyldimethylammonium chloride solution. 0.144g of sodium polystyrene sulfonate with a molecular weight of 100000 is dissolved in 100ml water, then 1.461g of sodium chloride is added, and stirred to obtain sodium polystyrene sulfonate solution. 0.4g of titanium dioxide with a particle size of 20nm is dissolved in 200ml water, stirred to obtain titanium dioxide solution. 400mg of polyallylamine hydrochloride is dissolved in 200ml water, then 20mg of sodium chloride is added, stirred to obtain polyallylamine hydrochloride solution. 200mg of hyaluronic acid is dissolved in 200ml water, then 18mg of sodium chloride is added, stirred to obtain hyaluronic acid solution. Add the prepared polydiallyldimethylammonium chloride solution to the reaction cell where the long period grating is fixed, let it stand for 10 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared sodium polystyrene sulfonate solution, let it stand for 20 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared titanium dioxide solution, let it stand for 20 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Repeat the above steps to add sodium polystyrene sulfonate solution or titanium dioxide solution in sequence, and assemble until the long period grating is in the best sensitive area to the refractive index. Then add the prepared hyaluronic acid solution, let it stand for 20 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Then add the prepared polyallylamine hydrochloride solution, let it stand for 20 minutes, then rinse it thoroughly with water and blow it dry with nitrogen. Repeat the above steps, alternately add hyaluronic acid solution or polyallylamine hydrochloride solution, assemble 40 layers of hyaluronic acid / polyallylamine hydrochloride nanofilms, and a long period grating with good response to pH is obtained.

[0047] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0048] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing LPFG for detecting pH value, characterized in that: The following steps are involved: (1) preparing a polydiallyldimethylammonium chloride solution, a sodium polystyrene sulfonate solution, a titanium dioxide solution, a hyaluronic acid solution and a polyallylamine hydrochloride solution respectively and setting them aside; (2) straightening the long period grating LPFG and fixing it in a liquid pool with a clamp; (3) Cleaning the long-period grating area; (4) adding a polydiallyldimethylammonium chloride solution into the liquid pool, and assembling a polydiallyldimethylammonium chloride film on the surface of the long period grating region; (5) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen; (6) adding a sodium polystyrene sulfonate solution into the liquid pool, and assembling a sodium polystyrene sulfonate film on the surface of the long period grating region; (7) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen; (8) adding a titanium dioxide solution into the liquid pool, and assembling a titanium dioxide film on the surface of the long period grating region; (9) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen; (10) Repeat the steps (6) to (9) until the long-period grating is in the optimal refractive index sensitive area; (11) adding the hyaluronic acid solution into the liquid pool, and continuing to assemble the hyaluronic acid film on the surface of the titanium dioxide film in the long period grating region; (12) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen gas; (13) adding a polyallylamine hydrochloride solution into the liquid pool to assemble a polyallylamine hydrochloride film on the surface of the long period grating region; (14) Rinse the long-period grating area thoroughly with distilled water and blow dry with nitrogen gas; (15) Repeat the steps (11) to (14) to assemble the required number of layers, thereby obtaining a long period grating that can be used to detect pH value; Dissolving polydiallyl dimethyl ammonium chloride in water, then adding sodium chloride and stirring evenly to obtain the polydiallyl dimethyl ammonium chloride solution; the molar concentration ratio of the polydiallyl dimethyl ammonium chloride to sodium chloride is in the range of 1:0.001-30000; The sodium polystyrene sulfonate solution is prepared by the following method: dissolving sodium polystyrene sulfonate in water, then adding sodium chloride and stirring evenly to obtain the sodium polystyrene sulfonate solution; the molar concentration ratio of the sodium polystyrene sulfonate to the sodium chloride is in the range of 1:0.001-30000; The concentration of the titanium dioxide solution is 0.0001 mg / mL-10 g / mL; the pH of the titanium dioxide solution is 2.8-5.8; the particle size of the titanium dioxide in the titanium dioxide solution is 0.001-500 μm; The concentrations of the hyaluronic acid solution and the polyallylamine hydrochloride solution are both 0.0001-0.1 mol / L, and the pH values ​​are both 3-10; The hyaluronic acid solution and the polyallylamine hydrochloride solution both contain sodium chloride at a concentration of 0-0.3 mol / L; The assembling on the surface of the long-period grating region in steps (4), (6), (8), (11) and (13) is specifically performed on the surface of the long-period grating region cladding layer after being straightened and fixed; The time for assembling on the surface of the long-period grating region in steps (4), (6), (8), (11) and (13) is 1-30 minutes; The detection range of pH value of the long period grating described in step (15) is 3 to 10.

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