Construction method of optical sensor for visually and dynamically monitoring tension change

Abstract

The invention provides a construction method of an optical sensor for dynamically and visually monitoring tension change. The preparation method comprises the following steps: step 1, preparing monodisperse ferroferric oxide nanoclusters with superparamagnetism and proper size, and coating the ferroferric oxide nanoclusters with a silicon dioxide shell layer; and 2, combining the magnetic nano unit with an acrylamide hydrogel system, and assembling and constructing the optical sensor with the capability of visually monitoring the tension change under an external magnetic field. The novel mechanochromic optical sensor constructed by the invention can be assembled in real time under an external magnetic field to form a one-dimensional straight-chain structure with a periodic structure. Meanwhile, covalent bonds and hydrogen bonds generated after the magnetic chain structure is combined with the acrylamide hydrogel enable the obtained composite optical gel to have better tensile property and higher breaking stress. Meanwhile, the optical sensor can realize visual monitoring of tension within 10-40kPa, the structural color is changed from orange red to blue, and the spectrum peak is blue-shifted from 680nm to 530nm. The magnetic field induction assembly technology has the advantage of quickly constructing an optical sensing platform, and a new construction thought can be provided for real-time, reversible and dynamic visual monitoring of tension.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensing and relates to a construction method and application of an optical sensor for visually and dynamically monitoring tension changes. Background Art

[0002] Photonic crystals are a type of visual functional material formed by periodically arranging media with different refractive indices. In recent years, artificial photonic crystal materials based on submicron-scale ordered assembly structures have attracted widespread attention due to their spontaneous iridescence effect and stimulus-responsive properties. Compared with traditional top-down lithography or microfabrication technologies, which have limitations such as high energy consumption and complex processes, colloidal self-assembly methods can achieve functional design and structurally controllable construction of photonic crystal materials by regulating multiple interactions between primitives. For example, cellulose nanocrystal orientation, block copolymer self-assembly, and capillary force-driven assembly are widely used to prepare photonic crystals with dynamic optical responses. However, the above methods usually rely on strict pretreatment conditions and lengthy assembly cycles, which are difficult to meet the needs of rapid preparation of high-quality photonic crystals.

[0003] For this reason, magnetic nanoparticles are considered to be one of the ideal building blocks for constructing dynamic photonic crystals because they can achieve instantaneous ordered arrangement through contactless magnetic field control. By adjusting the intensity or direction of the magnetic field, magnetically responsive photonic crystals can achieve real-time structural color control in aqueous or non-polar solvent systems. By combining photonic crystals with stimuli-responsive gels, new flexible sensing materials can be constructed that have the ability to monitor changes in external stimuli in real time with the naked eye under light. In addition, using a renewable white light source as an energy source, photonic crystal sensors are also a new optical nanomaterial that is expected to achieve zero energy consumption. By using photonic crystal gel sensing technology and combining it with magnetically induced in situ polymerization technology to integrate elastic polymer networks with magnetically responsive photonic crystals, mechanochromic optical sensors with both mechanical flexibility and optical responsiveness can be accurately prepared, providing a new way to develop mechanochromic sensors that are both mechanical and flexible. Summary of the Invention

[0004] The present invention aims to provide a magnetically induced optical sensor for dynamically monitoring changes in tension. This sensor features simple manufacturing and rapid assembly. Using magnetically induced assembly technology, the sensor is constructed to visualize the tension-induced chromic optical sensor and provide visual monitoring of tension.

[0005] The method for constructing a magnetically induced optical sensor for dynamically monitoring tension changes in the present invention comprises the following steps:

[0006] Step 1: Preparation of monodisperse Fe3O4 nanoclusters:

[0007] Ethylene glycol, anhydrous ferric chloride, anhydrous sodium acetate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, L(+)-ascorbic acid, and a trace amount of deionized water are sequentially added to a beaker and uniformly mixed by magnetic stirring; sodium hydroxide is added and vigorously magnetically stirred to obtain solution A; after the added substances are completely dissolved, the mixture is transferred to a conical flask and placed in a preheated oven for reaction; after completion of the reaction, a black precipitate is collected by magnetic separation, washed sequentially with an ethanol / water mixture and then with water by centrifugation, and finally dispersed in deionized water to obtain monodisperse ferrosoferric oxide nanoclusters for later use;

[0008] Step 2: Preparation of Fe3O4@SiO2 nanoparticles:

[0009] An aqueous solution of ferroferric oxide nanoclusters is mixed with anhydrous ethanol and ammonia water and ultrasonically mixed to obtain solution B. Solution B is then transferred to a three-necked flask with a mechanical stirrer and stirred evenly in a hot water bath. Ethyl orthosilicate is added dropwise to the system via a pipette to initiate the coating reaction. After the reaction, the sample is magnetically separated, washed sequentially with ethanol and deionized water by centrifugation, and finally dispersed in deionized water to obtain ferroferric oxide@silica core-shell nanoparticles for later use.

[0010] Step 3: Preparation of tensile chromic optical sensor:

[0011] A clean glass slide was used as the base, and a spacer layer of a certain thickness was fixed on the short sides of the base. A blank glass slide was placed on top of the sample to form a space sandwich. Acrylamide, N,N'-methylenebisacrylamide, and 2,2-diethoxyacetophenone solution were added to the aqueous solution of ferroferric oxide and silicon dioxide particles to form a prepolymer mixture C. The mixture C was injected into the interlayer gap and polymerized under an external magnetic field and ultraviolet light. After the reaction was completed, a tensile-chromic optical sensor device was obtained.

[0012] In step 1, in the solution A, the amount ratio of ethylene glycol, anhydrous ferric chloride, anhydrous sodium acetate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, L(+)-ascorbic acid, deionized water, and sodium hydroxide is 40mL:0.65g:3.0g:1.05g:12-14mg:50-120μL:0.6g; the first magnetic stirring speed is 500rpm, and the time is 40 minutes; the second strong magnetic stirring speed is 1200rpm, and the time is 2 hours; the reaction temperature in the oven is 190°C, the reaction time is 9 hours, and the volume of deionized water used to disperse the ferrosoferric oxide nanoclusters is 30mL.

[0013] In step 2, in the solution B, the ratio of the ferrosoferric oxide nanocluster aqueous solution, anhydrous ethanol, and ammonia water is 12 mL: 80 mL: 4 mL; the hot water bath temperature is 40° C.; the amount of ethyl orthosilicate added each time is 200 μL, and the reaction time is 20 minutes.

[0014] In step 3, the size of the interlayer formed in the space interlayer is 4 cm×2.5 cm×0.3 cm (length×width×height).

[0015] In step 3, the solution C contains ferroferric oxide@silicon dioxide particles aqueous solution (10 mg / mL), acrylamide, N,N'-methylenebisacrylamide, 10% 2,2-diethoxyacetophenone DEAP solution (V DEAP :V 二甲基亚砜 =1:9) is: 1 mL: 0.2 g: 0.005 g: 14 μL.

[0016] In step 3, the wavelength of the ultraviolet light is 365 nm, and the light focusing time is 5 minutes; the magnetic field is a parallel magnetic field with an intensity of 323 Gs, and the direction of the magnetic flux lines is perpendicular to the substrate surface.

[0017] The magnetically induced optical sensor constructed in the present invention is used to visually monitor tension. The magnetically induced optical sensor is placed in a natural state (stretching rate = 0%), and the reflection spectrum peaks and structural colors are recorded using an optical fiber spectrometer. The two sides of the optical sensor are evenly pulled with a tensile force of 10-40 kPa, and the reflection spectrum peaks and structural colors are again recorded using the optical fiber spectrometer under different stretching degrees (stretching rate: 50%-300%).

[0018] The beneficial effects of the present invention are:

[0019] The present invention prepares magnetic core-shell nanoparticles as assembly units, successfully constructs a mechanochromic optical sensing platform, and establishes a method for optical and visual monitoring of tension. Its features and advantages are described as follows:

[0020] (1) The present invention prepares a one-dimensional photonic crystal based on the magnetically induced self-assembly of ferroferric oxide and silicon dioxide nanoparticles as an optical platform to provide a reflection spectrum and structural color signals, and invents a magnetically induced self-assembly method that can achieve rapid and reversible design of structural base colors.

[0021] (2) The present invention improves the tensile properties and fracture stress of polyacrylamide gel by introducing a self-assembled chain structure, and prepares a new type of mechanochromic optical sensor with visual response capability to applied tension.

[0022] (3) The present invention realizes visual semi-quantitative and optical quantitative monitoring of 10-40 kPa tensile force through the constructed mechanochromic optical sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The scanning electron microscopy and transmission electron microscopy images of the prepared ferroferric oxide@silicon dioxide nanoparticles;

[0024] Figure 2 The scanning electron microscope and optical microscope images of the prepared one-dimensional optical sensor;

[0025] Figure 3 The relationship between the stretching degree and stress of the prepared one-dimensional optical sensor (red) and polyacrylamide film (transparent, without nanoparticles) is shown in the inset. The corresponding structural color image is shown in the inset.

[0026] Figure 4 Actual pictures of the structural colors of the prepared one-dimensional optical sensor under different stretching degrees;

[0027] Figure 5 The corresponding spectra of the prepared one-dimensional optical sensor under different stretching degrees. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to examples and accompanying drawings, but the present invention is not limited to these embodiments;

[0029] Example 1

[0030] (1) 40 mL of ethylene glycol, 0.65 g of anhydrous ferric chloride, 3.0 g of anhydrous sodium acetate, 1.05 g of poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, 14 mg of L(+)-ascorbic acid and 120 μL of deionized water were added to a beaker in sequence, and stirred under magnetic stirring at 500 rpm for 40 minutes to mix the system evenly; 0.6 g of sodium hydroxide was added, and magnetic stirring was carried out at 1200 rpm for 2 hours to obtain a completely dissolved solution; the mixture system was then transferred to a conical flask and placed in a preheated oven at 190°C for reaction for 9 hours; after the reaction was completed, a black precipitate was collected by magnetic separation, washed three times with an ethanol / water mixture and water by centrifugation, and finally dispersed in 30 mL of deionized water to obtain monodisperse ferrosoferric oxide nanoclusters with a particle size of 130 nm.

[0031] (2) 12 mL of the above-mentioned ferroferric oxide nanocluster aqueous solution was mixed with 80 mL of anhydrous ethanol and 4 mL of ammonia water, and ultrasonically mixed; then, the solution was transferred to a three-necked flask with a mechanical stirrer and stirred evenly in a 40°C hot water bath; 200 μL of ethyl orthosilicate was added dropwise to the system through a pipette, and the reaction began; after 20 minutes of reaction, 200 μL of ethyl orthosilicate was added again and the reaction continued for 20 minutes; after the reaction, the sample was magnetically separated, centrifuged and washed three times with ethanol and deionized water in sequence, and finally dispersed in 30 mL of deionized water to obtain 130@20 nm ferroferric oxide@silica core-shell structure nanoparticles.

[0032] (3) A clean glass slide was used as the bottom plate, and a spacer layer of a certain thickness was fixed on the short sides of the bottom plate. A blank glass slide was placed on the top of the sample to form a space sandwich of 4 cm × 2.5 cm × 0.3 cm (length × width × height). 0.2 g of acrylamide, 5 mg of N,N'-methylenebisacrylamide, and 2,2-diethoxyacetophenone solution (10%; V) were added to 1 mL of the ferroferric oxide@silica particle aqueous solution. DEAP :V 二甲基亚砜 =1:9) 14 μL to form a prepolymer mixture; the mixture was injected into the interlayer gap, and the polymerization reaction was carried out for 5 minutes under an external magnetic field of 323 Gs and 365 nm ultraviolet light. After the reaction was completed, an optical sensor device with a base color of red was obtained.

[0033] The size and microstructure of the Fe3O4@SiO2 nanoparticles obtained by the method of Example 1 of the present invention were characterized by field emission scanning electron microscopy and transmission electron microscopy. Figure 1 . Figure 1 The results show that the obtained Fe3O4@SiO2 nanoparticles are uniform in size, monodisperse, and have a clear core-shell structure, indicating the formation of a silica shell.

[0034] The optical sensor device with a red primary color obtained by the method of Example 1 of the present invention was characterized by scanning electron microscopy and optical microscopy. The chain-like superstructure and microscopic color of the assembled device were characterized. Figure 2 . Figure 2 It shows that under magnetic field induction and photocuring technology, a one-dimensional straight chain superstructure can be assembled, and obvious red bright spots can be observed in the direction parallel to the magnetic field in the obtained chain structure, indicating that the structural color comes from the periodic arrangement of the chain structure along the direction of the magnetic field.

[0035] The optical sensor device with a primary color of red obtained by the method of Example 1 of the present invention was characterized for its stretchability and corresponding stress. The results are shown in FIG. Figure 3 . Figure 3It shows that compared with pure polyacrylamide gel, the introduction of magnetic nanochains not only introduces a variable structural base color, but also improves the stretchability and fracture stress of the gel.

[0036] Example 2

[0037] (1) 40 mL of ethylene glycol, 0.65 g of anhydrous ferric chloride, 3.0 g of anhydrous sodium acetate, 1.05 g of poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, 12 mg of L(+)-ascorbic acid and 120 μL of deionized water were added to a beaker in sequence, and stirred under magnetic stirring at 500 rpm for 40 minutes to mix the system evenly; 0.6 g of sodium hydroxide was added, and magnetic stirring was carried out at 1200 rpm for 2 hours to obtain a completely dissolved solution; the mixture system was then transferred to a conical flask and placed in a preheated oven at 190°C for reaction for 9 hours; after the reaction was completed, a black precipitate was collected by magnetic separation, washed three times with an ethanol / water mixture and water by centrifugation, and finally dispersed in 30 mL of deionized water to obtain monodisperse ferroferric oxide nanoclusters with a particle size of 120 nm.

[0038] (2) 12 mL of the above-mentioned ferroferric oxide nanocluster aqueous solution was mixed with 80 mL of anhydrous ethanol and 4 mL of ammonia water, and ultrasonically mixed; then, the solution was transferred to a three-necked flask with a mechanical stirrer and stirred evenly in a 40°C hot water bath; 200 μL of ethyl orthosilicate was added dropwise to the system through a pipette, and the reaction began; after 20 minutes of reaction, the sample was magnetically separated and centrifuged three times with ethanol and deionized water in sequence, and finally dispersed in 30 mL of deionized water to obtain 130@10 nm ferroferric oxide@silica core-shell structured nanoparticles.

[0039] (3) A clean glass slide was used as the bottom plate, and a spacer layer of a certain thickness was fixed on the short sides of the bottom plate. A blank glass slide was placed on the top of the sample to form a space sandwich of 4 cm × 2.5 cm × 0.3 cm (length × width × height). 0.2 g of acrylamide, 5 mg of N,N'-methylenebisacrylamide, and 2,2-diethoxyacetophenone solution (10%; V) were added to 1 mL of the ferroferric oxide@silica particle aqueous solution. DEAP :V 二甲基亚砜 =1:9) 14 μL to form a prepolymer mixture; the mixture was injected into the interlayer gap, and the polymerization reaction was carried out under an external magnetic field of 323 Gs and 365 nm ultraviolet light for 5 minutes. After the reaction was completed, an optical sensor device with a base color of blue was obtained.

[0040] Example 3

[0041] (1) 40 mL of ethylene glycol, 0.65 g of anhydrous ferric chloride, 3.0 g of anhydrous sodium acetate, 1.05 g of poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, 12 mg of L(+)-ascorbic acid and 50 μL of deionized water were added to a beaker in sequence, and stirred under magnetic stirring at 500 rpm for 40 minutes to mix the system evenly; 0.6 g of sodium hydroxide was added, and magnetic stirring was carried out at 1200 rpm for 2 hours to obtain a completely dissolved solution; the mixture system was then transferred to a conical flask and placed in a preheated oven at 190°C for reaction for 9 hours; after the reaction was completed, a black precipitate was collected by magnetic separation, washed three times with an ethanol / water mixture and water by centrifugation, and finally dispersed in 30 mL of deionized water to obtain monodisperse ferroferric oxide nanoclusters with a particle size of 150 nm.

[0042] (2) 12 mL of the above-mentioned ferroferric oxide nanocluster aqueous solution was mixed with 80 mL of anhydrous ethanol and 4 mL of ammonia water, and ultrasonically mixed; then, the solution was transferred to a three-necked flask with a mechanical stirrer and stirred evenly in a 40°C hot water bath; 200 μL of ethyl orthosilicate was added dropwise to the system through a pipette, and the reaction began; after 20 minutes of reaction, 200 μL of ethyl orthosilicate was added again and the reaction continued for 20 minutes; after the reaction, the sample was magnetically separated, centrifuged and washed three times with ethanol and deionized water in sequence, and finally dispersed in 30 mL of deionized water to obtain 150@20 nm ferroferric oxide@silica core-shell structure nanoparticles.

[0043] (3) A clean glass slide was used as the bottom plate, and a spacer layer of a certain thickness was fixed on the short sides of the bottom plate. A blank glass slide was placed on the top of the sample to form a space sandwich of 4 cm × 2.5 cm × 0.3 cm (length × width × height). 0.2 g of acrylamide, 5 mg of N,N'-methylenebisacrylamide, and 2,2-diethoxyacetophenone solution (10%; V) were added to 1 mL of the ferroferric oxide@silica particle aqueous solution. DEAP :V 二甲基亚砜 =1:9) 14 μL to form a prepolymer mixture; the mixture was injected into the interlayer gap, and the polymerization reaction was carried out for 5 minutes under an external magnetic field of 323 Gs and 365 nm ultraviolet light. After the reaction was completed, an optical sensor device with a base color of red was obtained.

[0044] Example 4

[0045] (1) The red optical sensor in Example 1 was used to visually monitor the tension, the magnetically induced optical sensor was placed in a natural state (stretching rate = 0%), and the reflected spectrum peak and structural color were recorded using a fiber optic spectrometer. Different tensile forces were used to evenly pull the two sides of the optical sensor, and the reflected spectrum peak and structural color were again recorded using a fiber optic spectrometer at different stretching degrees (stretching rate: 50%-300%).

[0046] The structural color change and reflectance spectrum results tested by the method of Example 4 of the present invention are as follows Figure 4-5 shown. Figure 4 It shows that as the film is continuously stretched from 0% to 300%, its structural color gradually shifts from orange-red to blue-purple. Figure 5 It shows that as the film is stretched, its spectral peak gradually blue-shifts from 680 nm to 530 nm, and the peak intensity decreases with the increase of stretching force.

Claims

1. A method for constructing an optical sensor for dynamic visual monitoring of tension changes, characterized in that: The steps include: Step 1: Preparation of monodisperse Fe3O4 nanoclusters: First, ethylene glycol, anhydrous ferric chloride, anhydrous sodium acetate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, L(+)-ascorbic acid, and a trace amount of deionized water are sequentially added to a beaker and uniformly mixed by magnetic stirring. Subsequently, sodium hydroxide is added and vigorously magnetically stirred to obtain solution A. After the added substances are completely dissolved, the mixture is transferred to a conical flask and placed in a preheated oven for reaction. After the reaction is completed, a black precipitate is collected by magnetic separation, washed sequentially with an ethanol / water mixture and then with water by centrifugation, and finally dispersed in deionized water to obtain monodisperse ferrosoferric oxide nanoclusters for later use. Step 2: Preparation of Fe3O4@SiO2 nanoparticles: First, an aqueous solution of ferroferric oxide nanoclusters is mixed with anhydrous ethanol and ammonia water and ultrasonically mixed to obtain solution B. Solution B is then transferred to a three-necked flask with a mechanical stirrer and stirred evenly in a hot water bath. Then, ethyl orthosilicate is added dropwise to the system via a pipette to initiate the coating reaction. After the reaction is completed, the sample is magnetically separated, centrifuged and washed with ethanol and deionized water, and finally dispersed in deionized water to obtain ferroferric oxide@silica core-shell nanoparticles for later use. Step 3: Preparation of tensile chromic optical sensor: First, a clean glass slide is used as the base, a spacer layer of a certain thickness is fixed on the short sides of the base, and a blank glass slide is placed on top of the sample to form a space sandwich; Subsequently, acrylamide, N,N'-methylenebisacrylamide, and 2,2-diethoxyacetophenone solution were added to the ferroferric oxide@silica particle aqueous solution to form a prepolymer mixture C. Then, the mixture C was injected into the interlayer gap and polymerized under an external magnetic field and ultraviolet light. After the reaction was completed, a tensile-chromic optical sensor device was obtained.

2. The construction method according to claim 1, wherein In step 1, in the solution A, the amount ratio of ethylene glycol, anhydrous ferric chloride, anhydrous sodium acetate, poly(4-styrenesulfonic acid-co-maleic acid) sodium salt, L(+)-ascorbic acid, deionized water, and sodium hydroxide is 40mL:0.65g:3.0g:1.05g:12-14mg:50-120μL:0.6g; the first magnetic stirring speed is 500rpm, and the time is 40 minutes; the second strong magnetic stirring speed is 1200rpm, and the time is 2 hours; the reaction temperature in the oven is 190°C, the reaction time is 9 hours, and the volume of deionized water used to disperse the ferrosoferric oxide nanoclusters is 30mL.

3. The construction method according to claim 1, wherein In step 2, in the solution B, the ratio of the ferrosoferric oxide nanocluster aqueous solution, anhydrous ethanol, and ammonia water is 12 mL: 80 mL: 4 mL; the hot water bath temperature is 40° C.; the amount of ethyl orthosilicate added each time is 200 μL, and the reaction time is 20 minutes.

4. The construction method according to claim 1, wherein In step 3, the size of the interlayer formed in the space interlayer is 4 cm×2.5 cm×0.3 cm (length×width×height).

5. The construction method according to claim 1, wherein: In step 3, the solution C contains ferroferric oxide@silicon dioxide particles aqueous solution (10 mg / mL), acrylamide, N,N'-methylenebisacrylamide, 10% 2,2-diethoxyacetophenone DEAP solution (V DEAP :V 二甲基亚砜 =1:9) is: 1 mL: 0.2 g: 0.005 g: 14 μL.

6. The construction method according to claim 1, wherein: In step 3, the wavelength of the ultraviolet light is 365 nm, and the light focusing time is 5 minutes; the magnetic field is a parallel magnetic field with an intensity of 323 Gs, and the direction of the magnetic flux lines is perpendicular to the substrate surface.

7. Use of the magnetically induced optical sensor constructed by the construction method according to claims 1 to 6 for visually monitoring tension, characterized in that: The monitoring steps are: (1) The magnetically induced optical sensor was placed in a natural state (stretching rate = 0%), and the reflected spectrum peak and structural color were recorded using a fiber optic spectrometer; (2) The two sides of the optical sensor were pulled evenly with different pulling forces, and the optical fiber spectrometer was used to record its reflection spectrum peak and structural color again at different stretching degrees (stretching rate: 50%-300%).

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