Colorimetric sensor based on one-dimensional photonic crystal as well as preparation method and application of colorimetric sensor

Abstract

The invention relates to a colorimetric sensor based on a one-dimensional photonic crystal as well as a preparation method and application of the colorimetric sensor, and belongs to the field of preparation of novel sensing materials. A colorimetric sensor based on a one-dimensional photonic crystal is composed of a silicon substrate and a one-dimensional photonic crystal film coated on the silicon substrate, and the one-dimensional photonic crystal film is formed by orderly and alternately assembling a plurality of polymer material layers and material layers having refractive index differences with the polymer material layers. The reflection peak displacement of the colorimetric sensor has a linear relationship with the value of the gasoline concentration in the environment, and one color corresponds to the unique gasoline concentration in the environment, so that the gasoline gas around the material can be accurately identified, and meanwhile, visualization is realized. The colorimetric sensor disclosed by the invention is high in response speed and good in reversibility and cyclic color change stability, and has a good application prospect in the aspect of gasoline leakage monitoring.

Description

Technical Field

[0001] The present invention relates to a colorimetric sensor based on one-dimensional photonic crystal, its preparation method and application, belonging to the field of preparation of new sensing materials. Background Art

[0002] Currently, the detection means of gasoline gas mainly include electrochemical sensors, infrared spectroscopy sensors, semiconductor sensors, etc. Although these technologies have certain advantages in terms of sensitivity and response speed, they generally have the following technical defects and problems: First, some detection instruments rely on precision optical or electronic components, with complex structures and high prices, and are not suitable for large-scale or resource-limited places. Moreover, some detection instruments need to be calibrated regularly or the probes need to be replaced, with complex operation procedures and high maintenance and use thresholds; Second, most of the existing sensors mainly output electronic signals, unable to intuitively reflect the change of gas concentration, with insufficient real-time visualization ability. At the same time, the sensors are sensitive to temperature and humidity, vulnerable to environmental interference, and may have cross-response in a complex gas environment, resulting in low detection accuracy and selectivity.

[0003] A colorimetric sensor is a sensing device that can convert environmental changes into color changes, and has received wide attention due to its advantages such as simple operation, low cost, and intuitive response. A photonic crystal is a periodic dielectric structure with photonic bandgap characteristics. When its bandgap falls within the visible light range, it can present a structural color and has good color response ability. By developing a new type of photonic crystal colorimetric sensor with a more stable structure, more sensitive response, and more intuitive color change, the rapid visual detection requirements of explosive gases such as gasoline can be met. Summary of the Invention

[0004] The present invention provides a colorimetric sensor based on one-dimensional photonic crystal, its preparation method and application, specifically providing an organic / inorganic composite one-dimensional photonic crystal colorimetric sensor with bright color and high sensitivity, its preparation method and application. The colorimetric sensor of the present invention is coated with a one-dimensional photonic crystal film on a silicon wafer that has undergone hydrophilic treatment. When the sensor is placed in an environment containing gasoline gas, the one-dimensional photonic crystal film absorbs gasoline gas in the air and swells simultaneously, causing an orderly change in the film layer thickness, resulting in a change in the lattice spacing or effective refractive index of the photonic crystal, and the color of the sensor changes rapidly, and the color change is visible to the naked eye. Furthermore, the size of the gasoline concentration can be monitored, realizing visual sensing.

[0005] A colorimetric sensor based on one-dimensional photonic crystal is composed of a silicon substrate and a one-dimensional photonic crystal film coated on the silicon substrate. The one-dimensional photonic crystal film is composed of several polymer material layers and material layers with a refractive index difference from the above polymers assembled in an orderly and alternating manner. Among them,

[0006] the silicon substrate is a silicon wafer that has undergone hydrophilic treatment;

[0007] The refractive index difference between Polymer A in the polymer material layer and Material B in the material layer with a refractive index difference from the above polymer is greater than or equal to 0.2;

[0008] The Polymer A is poly(tert-butyl methacrylate), poly(butyl acrylate), polyoctene, polyacrylonitrile, a copolymer of tert-butyl methacrylate and acrylic acid, or polyisoprene;

[0009] The Material B is titanium dioxide, barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polyisoprene, polyoctene, poly(tert-butyl methacrylate), polymethyl methacrylate, polystyrene, polycarbonate, polydimethylsiloxane, or a mixture of Polymer A and the above materials;

[0010] When the Material B is a mixture of Polymer A and the above materials, the mass fraction of Polymer A is 10% - 90%.

[0011] Furthermore, Polymer A and Material B cannot be simultaneously selected as the same substance.

[0012] Preferably, the refractive index difference between Polymer A in the polymer material layer and Material B in the material layer with a refractive index difference from the above polymer is 0.7 - 1.5.

[0013] Preferably, the Polymer A is polyisoprene and the Material B is titanium dioxide.

[0014] Preferably, the layer in contact with the silicon substrate is the polymer material layer.

[0015] Preferably, the assembly period of the polymer material layer and the material layer with a refractive index difference from the above polymer in the one-dimensional photonic crystal film is 3 - 5.

[0016] One assembly period of the one-dimensional photonic crystal film of the present invention is one layer of polymer material layer and one layer of material layer with a refractive index difference from the above polymer. The more the number of assembly periods, the brighter the color, but the response effect also decreases accordingly.

[0017] More preferably, the assembly period of the polymer material layer and the material layer with a refractive index difference from the above polymer in the one-dimensional photonic crystal film is 3.

[0018] In the above technical solution, the hydrophilic treatment method is to place the silicon wafer in deionized water, heat it to 50 - 180°C, and add a mixed solution of hydrogen peroxide and ammonia water for treatment for 1 - 60 minutes.

[0019] Furthermore, the volume ratio of hydrogen peroxide to ammonia water in the mixed solution of hydrogen peroxide and ammonia water is 10:1 - 50.

[0020] Further, the volume ratio of the deionized water, hydrogen peroxide and ammonia water mixed solution is 10:1 to 20.

[0021] Furthermore, after the silicon wafer treated by the hydrophilic treatment is taken out, it is washed with ethanol for multiple times, and then can be directly dried with a hair dryer, cleaned with a dust-free cloth on the surface and used immediately, or placed in an ethanol solution for standby.

[0022] In the above technical solution, the thickness of the silicon substrate is greater than 1 mm.

[0023] In the above technical solution, the sum of the optical thicknesses of each assembly period of the one-dimensional photonic crystal film is 100 - 300 nm.

[0024] Another object of the present invention is to provide a preparation method of the colorimetric sensor based on the one-dimensional photonic crystal, including the following steps:

[0025] ① Performing plasma treatment on the silicon substrate for 30 s;

[0026] ② Preparing a polymer dispersion;

[0027] ③ Preparing a dispersion of a material having a refractive index difference from the above polymer;

[0028] ④ Spin-coating the polymer dispersion obtained in the above step ② on the silicon substrate, adjusting the spin-coating conditions to control the film thickness, heating and drying, and then spin-coating the material dispersion obtained in the above step ③ on the dried material, adjusting the spin-coating conditions to control the film thickness, heating and drying, and repeating the above steps 0 - 15 times to obtain.

[0029] Further, the mass fractions of both the polymer dispersion and the dispersion of the material having a refractive index difference from the above polymer are 0.5% - 20%.

[0030] Further, the heating and drying conditions are heating at 30 - 200 °C for 1 - 60 min.

[0031] A preferred technical solution of the present invention includes the following steps:

[0032] ① Preparation of the silicon substrate: placing a silicon wafer with a thickness greater than 1 mm in water and heating to 50 - 180 °C, adding a hydrogen peroxide and ammonia water mixed solution for treatment for 1 - 60 min, taking it out and washing it with ethanol for multiple times to obtain a silicon substrate, and then placing it in an ethanol solution for standby; taking out the silicon wafer reserved in ethanol, drying it with a hair dryer, cleaning the surface with a dust-free cloth, and performing 30 s plasma treatment with a plasma processor;

[0033] ② Preparation of the polymer dispersion: measuring the polymer dispersion, adjusting the concentration, and ultrasonicating for 5 - 30 min to obtain;

[0034] ③ Preparation of the dispersion of the material with a refractive index difference from the above polymer: Weigh the material with a refractive index difference from the above polymer, add it to deionized water or an aqueous solution of absolute ethanol, and ultrasonicate for 5 - 30 min to obtain it.

[0035] ④ Preparation of the colorimetric sensor: Spin - coat the polymer dispersion obtained in the above step ② on a silicon substrate, adjust the spin - coating conditions to control the film thickness, heat and dry it. Then, continue to spin - coat the material dispersion obtained in the above step ③ on the dried material, adjust the spin - coating conditions to control the film thickness, heat and dry it. The above steps are repeated 0 - 15 times to obtain it.

[0036] Further, in the above step ②, the polymer in the polymer dispersion can be obtained by purchase or prepared according to the existing technology.

[0037] Furthermore, the preparation method of the tert - butyl methacrylate - acrylic acid copolymer dispersion is to mix two monomers, tert - butyl methacrylate and acrylic acid, in a volume ratio of 10:1 to obtain a mixed monomer. After heating 2 mL of the above - mentioned mixed monomer, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate in a water bath to 75 °C, add 8 mL of the mixed monomer and 0.075 g of potassium persulfate and react for 1 h to obtain it.

[0038] Further, in the above step ③, the volume ratio of absolute ethanol to water in the aqueous solution of absolute ethanol is 1:1.

[0039] Another object of the present invention is to provide the application of the above - mentioned colorimetric sensor based on one - dimensional photonic crystals in detecting gasoline gas.

[0040] The beneficial effects of the present invention are as follows: The peak shift of the reflection of the colorimetric sensor based on one - dimensional photonic crystals of the present invention has a linear relationship with the value of the gasoline concentration in the environment. One color corresponds to a unique gasoline concentration in the environment, and thus the gasoline gas environment around it can be accurately identified to achieve visualization. The colorimetric sensor obtained in the present invention has a fast response speed, good reversibility and cyclic color - change stability, and has good application prospects in gasoline leakage monitoring. Description of the Drawings

[0041] Figure 1 It is a scanning electron microscope cross - sectional view of the one - dimensional photonic crystal colorimetric sensor obtained in Example 73.

[0042] Figure 2The figure shows the change in the reflection peak of the one-dimensional photonic crystal colorimetric sensor obtained in Example 73 in response to different concentrations of 95# gasoline. It can be seen that as the concentration of 95# gasoline increases, the reflection peak of the colorimetric sensor gradually redshifts; the linear relationship between the gasoline concentration and the reflection peak position is y = 0.28x + 472; when the reflection peak shifts by 1 nm, it is the detection limit of the photonic crystal, that is, the detection limit of the photonic crystal for gasoline gas is 3.57 g / m 3 。

[0043] Figure 3 The figure shows the color photos of the one-dimensional photonic crystal colorimetric sensor obtained in Example 73 in response to different concentrations of 95# gasoline. It can be seen that as the concentration of 95# gasoline increases, the color of the colorimetric sensor continuously changes.

[0044] Figure 4 The figure shows the change in the reflection spectrum of the one-dimensional photonic crystal colorimetric sensor obtained in Example 73 in response to time. It can be seen that the color change is completed within 0.5 s after introducing gasoline gas, and the initial state is restored within 0.3 s after introducing air.

[0045] Figure 5 The figure shows the change in the emission peak position of the one-dimensional photonic crystal colorimetric sensor obtained in Example 73 after being reused 100 times in a cycle. It can be seen that the colorimetric sensor described in the present invention has reversibility and good cyclic color change stability. Detailed implementation manners

[0046] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way.

[0047] In the following examples, the test methods are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0048] Example 1

[0049] A preparation method of a colorimetric sensor based on a one-dimensional photonic crystal includes the following steps:

[0050] ① Preparation of the silicon substrate: Place the purchased silicon wafer in 150 mL of water and heat it to 70 °C. Add 60 mL of a mixed solution of hydrogen peroxide and ammonia (the volume ratio of hydrogen peroxide to ammonia is 1:1) and treat it for 20 min to obtain the silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a dust-free cloth, and perform plasma treatment for 30 s using a plasma processor;

[0051] ② Preparation of polymer dispersion: Add 2 mL of tert-butyl methacrylate, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of tert-butyl methacrylate and 0.075 g of potassium persulfate for reaction for 1 h to obtain a poly(tert-butyl methacrylate) dispersion. Dilute the poly(tert-butyl methacrylate) dispersion with deionized water and ultrasonicate for 10 min to obtain a 5 wt% poly(tert-butyl methacrylate) dispersion;

[0052] ③ Preparation of dispersion of material with refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0053] ④ Spin-coat the 5 wt% poly(tert-butyl methacrylate) dispersion obtained in step ② above on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 190 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0054] Examples 2 - 9

[0055] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 1. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silica, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0056] Example 10

[0057] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0058] ① Preparation of silicon substrate: Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia (the volume ratio of hydrogen peroxide to ammonia is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0059] ② Preparation of polymer dispersion: Add 2 mL of tert-butyl methacrylate, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of tert-butyl methacrylate and 0.075 g of potassium persulfate for reaction for 1 h to obtain a poly(tert-butyl methacrylate) dispersion. Dilute the poly(tert-butyl methacrylate) dispersion with deionized water and then ultrasonicate for 10 min to obtain a 5 wt% poly(tert-butyl methacrylate) dispersion;

[0060] ③ Preparation of dispersion of material with refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0061] ④ Spin-coat the 5 wt% poly(tert-butyl methacrylate) dispersion obtained in step ② above on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 180 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0062] Examples 11 - 18

[0063] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 10. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0064] Example 19

[0065] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0066] ① Preparation of silicon substrate: Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0067] ② Preparation of polymer dispersion: Mix tert-butyl methacrylate and acrylic acid monomers in a volume ratio of 10:1. Add 2 mL of the mixed monomers, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of the mixed monomers and 0.075 g of potassium persulfate for reaction for 1 h to obtain a tert-butyl methacrylate-acrylic acid copolymer dispersion. Dilute the tert-butyl methacrylate-acrylic acid copolymer dispersion with deionized water and then ultrasonicate for 10 min to obtain a 5 wt% tert-butyl methacrylate-acrylic acid copolymer dispersion;

[0068] ③ Preparation of dispersion of material with refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0069] ④ Spin-coat the 5 wt% tert-butyl methacrylate-acrylic acid copolymer dispersion obtained in step ② above on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. Control the optical thickness of each cycle to be 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0070] Examples 20 - 27

[0071] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 19. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0072] Example 28

[0073] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0074] ① Preparation of silicon substrate: Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer and then clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0075] ② Preparation of polymer dispersion: Mix tert-butyl methacrylate and acrylic acid at a volume ratio of 10:1. Add 2 mL of the mixed monomers, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of the mixed monomers and 0.075 g of potassium persulfate for reaction for 1 h to obtain a tert-butyl methacrylate-acrylic acid copolymer dispersion. Dilute the tert-butyl methacrylate-acrylic acid copolymer dispersion with deionized water and then ultrasonicate for 10 min to obtain a 5 wt% tert-butyl methacrylate-acrylic acid copolymer dispersion;

[0076] ③ Preparation of dispersion of material with refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0077] ④ Spin-coat the 5 wt% tert-butyl methacrylate-acrylic acid copolymer dispersion obtained in step ② above on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 190 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0078] Examples 29 - 36

[0079] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 28. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0080] Example 37

[0081] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0082] ① Preparation of silicon substrate: Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0083] ② Preparation of polymer dispersion: Add 2 mL of octene, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of octene and 0.075 g of potassium persulfate and react for 5 h to obtain a polyoctene dispersion. Dilute the polyoctene dispersion with deionized water and then ultrasonicate for 10 min to obtain a 5 wt% polyoctene dispersion;

[0084] ③ Preparation of dispersion of material with refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0085] ④ Spin-coat the 5 wt% polyoctene dispersion obtained in step ② above on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, and heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles, and control the optical thickness of each cycle to be 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0086] Examples 38 - 45

[0087] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 37. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0088] Example 46

[0089] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0090] ① Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a dust-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0091] ② Preparation of polymer dispersion: Add 2 mL of octene, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of octene and 0.075 g of potassium persulfate and react for 5 h to obtain a polyoctene dispersion. Dilute the polyoctene dispersion with deionized water and then ultrasonicate for 10 min to obtain a 5 wt% polyoctene dispersion;

[0092] ③ Preparation of a dispersion of a material with a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonically disperse for 30 min to obtain a material dispersion;

[0093] ④ Spin-coat the 5 wt% polyoctene dispersion obtained in step ② on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles, and control the optical thickness of each cycle to be 180 nm to obtain a colorimetric sensor based on a one-dimensional photonic crystal.

[0094] Examples 47 - 54

[0095] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 48. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silica, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0096] Example 55

[0097] A preparation method of a colorimetric sensor based on a one-dimensional photonic crystal, comprising the following steps:

[0098] ① Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1), and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0099] ② Preparation of a polymer dispersion: Add 2 mL of acrylonitrile, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate to a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of acrylonitrile and 0.075 g of potassium persulfate and react for 1 h to obtain a polyacrylonitrile dispersion; Dilute the polyacrylonitrile dispersion with deionized water and ultrasonically disperse for 10 min to obtain a 5 wt% polyacrylonitrile dispersion;

[0100] ③ Preparation of a dispersion of a material with a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonically disperse for 30 min to obtain a material dispersion;

[0101] ④ Spin-coat the 5 wt% polyacrylonitrile dispersion obtained in step ② on the silicon substrate of step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystals.

[0102] Examples 56 - 63

[0103] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 55. In step ③, replace the titanium dioxide powder with barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders, respectively.

[0104] Example 64

[0105] A preparation method of a colorimetric sensor based on one-dimensional photonic crystals, comprising the following steps:

[0106] ① Place the purchased silicon wafer in 150 mL of water and heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1), and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment with a plasma processor for 30 s;

[0107] ② Prepare a polymer dispersion: Add 2 mL of acrylonitrile, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate to a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of acrylonitrile and 0.075 g of potassium persulfate and react for 1 h to obtain a polyacrylonitrile dispersion; Dilute the polyacrylonitrile dispersion with deionized water and ultrasonicate for 10 min to obtain a 5 wt% polyacrylonitrile dispersion;

[0108] ③ Prepare a dispersion of a material with a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0109] ④ Spin-coat the 5 wt% polyacrylonitrile dispersion obtained in step ② on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Then, continue to spin-coat the material dispersion obtained in step ③ on the dried material, adjust the spin-coating conditions to control the film thickness, and heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. Control the optical thickness of each cycle to 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystals.

[0110] Examples 65 - 72

[0111] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 64. In step ③, replace the titanium dioxide powder with barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders, respectively.

[0112] Example 73

[0113] A preparation method of a colorimetric sensor based on one-dimensional photonic crystals, comprising the following steps:

[0114] ① Place the purchased silicon wafer in 150 mL of water, heat to 70 °C, add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1), and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment for 30 s using a plasma processor;

[0115] ② Prepare a polymer dispersion: Add 10 mL of isoprene, 50 mL of deionized water, 0.8 g of sodium dodecyl sulfate, and 0.15 g of potassium persulfate to a 250 mL sealed flask, react at 75 °C in a water bath for 20 h to obtain a polyisoprene dispersion; Dilute the polyisoprene dispersion with deionized water and ultrasonicate for 10 min to obtain a 5 wt% polyisoprene dispersion;

[0116] ③ Prepare a dispersion of a material having a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0117] ④ Spin-coat the 5 wt% polyisoprene dispersion obtained in step ② on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Then, continue to spin-coat the material dispersion obtained in step ③ on the dried material, adjust the spin-coating conditions to control the film thickness, and heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. Control the optical thickness of each cycle to 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystals.

[0118] Examples 74 - 81

[0119] The preparation methods of the silicon substrate and the dispersion liquid are the same as those in Example 73. In step ③, barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders are used to replace the titanium dioxide powder respectively.

[0120] Example 82

[0121] A preparation method of a colorimetric sensor based on a one - dimensional photonic crystal includes the following steps:

[0122] ① Place the purchased silicon wafer in 150 mL of water and heat it to 70 °C. Add a mixed solution of 60 mL of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint - free cloth, and perform plasma treatment for 30 s using a plasma processor;

[0123] ② Prepare a polymer dispersion liquid: Add 10 mL of isoprene, 50 mL of deionized water, 0.8 g of sodium dodecyl sulfate, and 0.15 g of potassium persulfate into a 250 - mL sealed flask. After heating in a water bath to 75 °C, react for 20 h to obtain a polyisoprene dispersion liquid; Dilute the polyisoprene dispersion liquid with deionized water and ultrasonicate for 10 min to obtain a 5 wt% polyisoprene dispersion liquid;

[0124] ③ Prepare a dispersion liquid of a material with a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion liquid;

[0125] ④ Spin - coat the 5 wt% polyisoprene dispersion liquid obtained in step ② on the silicon substrate in step ①, adjust the spin - coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Then, continue to spin - coat the material dispersion liquid obtained in step ③ on the dried material, adjust the spin - coating conditions to control the film thickness, and heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 180 nm to obtain a colorimetric sensor based on a one - dimensional photonic crystal.

[0126] Examples 83 - 90

[0127] The preparation methods of the silicon substrate and the dispersion liquid are the same as those in Example 82. In step ③, barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders are used to replace the titanium dioxide powder respectively.

[0128] Example 91

[0129] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0130] ① Place the purchased silicon wafer in 150 mL of water and heat to 70 °C. Add 60 mL of a mixed solution of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times. After drying with a hair dryer, clean the surface with a lint-free cloth and perform plasma treatment with a plasma processor for 30 s;

[0131] ② Prepare a polymer dispersion: Add 2 mL of butyl acrylate, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate into a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of butyl acrylate and 0.15 g of potassium persulfate and react for 1 h to obtain a polybutyl acrylate dispersion. Dilute the polybutyl acrylate dispersion with deionized water and ultrasonicate for 10 min to obtain a 5 wt% polybutyl acrylate dispersion;

[0132] ③ Prepare a dispersion of a material having a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 50 mL of deionized water, and ultrasonicate for 30 min to make it evenly dispersed to obtain a material dispersion;

[0133] ④ Spin-coat the 5 wt% polybutyl acrylate dispersion obtained in step ② on the silicon substrate in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles, and control the optical thickness of each cycle to be 170 nm to obtain a colorimetric sensor based on one-dimensional photonic crystal.

[0134] Examples 92 - 99

[0135] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 91. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

[0136] Example 100

[0137] A preparation method of a colorimetric sensor based on one-dimensional photonic crystal, comprising the following steps:

[0138] ① Place the purchased silicon wafers in 150 mL of water and heat to 70 °C. Add a mixed solution of 60 mL of hydrogen peroxide and ammonia water (the volume ratio of hydrogen peroxide to ammonia water is 1:1) and treat for 20 min to obtain a silicon substrate. After taking it out, wash it with ethanol multiple times, dry it with a hair dryer, clean the surface with a lint-free cloth, and perform plasma treatment for 30 s using a plasma processor;

[0139] ② Prepare a polymer dispersion: Add 2 mL of butyl acrylate, 50 mL of deionized water, and 0.8 g of sodium dodecyl sulfate to a 250 mL three-necked flask. After heating in a water bath to 75 °C, add 8 mL of butyl acrylate and 0.075 g of potassium persulfate and react for 1 h to obtain a polybutyl acrylate dispersion. Dilute the polybutyl acrylate dispersion with deionized water and ultrasonicate for 10 min to obtain a 5 wt% polybutyl acrylate dispersion;

[0140] ③ Prepare a dispersion of a material with a refractive index difference from the above polymer: Weigh 1.5 g of titanium dioxide powder, add 25 mL of deionized water and 25 mL of absolute ethanol, and ultrasonicate for 30 min to disperse it evenly to obtain a material dispersion;

[0141] ④ Spin-coat the 5 wt% polybutyl acrylate dispersion obtained in step ② above on the silicon substrate obtained in step ①, adjust the spin-coating conditions to control the film thickness, heat and dry at 80 °C for 15 min, and then continue to spin-coat the material dispersion obtained in step ③ above on the dried material, adjust the spin-coating conditions to control the film thickness, and heat and dry at 80 °C for 15 min. Repeat the above steps 3 times, which is three assembly cycles. The optical thickness of each cycle is controlled to be 180 nm to obtain a colorimetric sensor based on a one-dimensional photonic crystal.

[0142] Examples 101 - 108

[0143] The preparation methods of the silicon substrate and the dispersion are the same as those in Example 100. In step ③, replace the titanium dioxide powder with barium titanate, zirconia, niobium oxide, lanthanum oxide, silicon dioxide, polymethyl methacrylate, polystyrene, and polycarbonate powders respectively.

Claims

1. A colorimetric sensor based on one-dimensional photonic crystal, characterized in that: The colorimetric sensor is composed of a silicon substrate and a one-dimensional photonic crystal film coated on the silicon substrate. The one-dimensional photonic crystal film is composed of several polymer material layers and material layers with a refractive index difference from the above polymers, which are orderly and alternately assembled. Among them, the silicon substrate is a silicon wafer treated by hydrophilic treatment; the refractive index difference between polymer A in the polymer material layer and material B in the material layer with a refractive index difference from the above polymers is greater than or equal to 0.2; the polymer A is poly(tert-butyl methacrylate), poly(butyl acrylate), polyoctene, polyacrylonitrile, a copolymer of tert-butyl methacrylate and acrylic acid, or polyisoprene; the material B is titanium dioxide, barium titanate, zirconium oxide, niobium oxide, lanthanum oxide, silicon dioxide, polyisoprene, polyoctene, poly(tert-butyl methacrylate), poly(methyl methacrylate), polystyrene, polycarbonate, polydimethylsiloxane, or a mixture of polymer A and the above materials; when the material B is a mixture of polymer A and the above materials, the mass fraction of polymer A is 10% to 90%.

2. The colorimetric sensor according to claim 1, wherein: the refractive index difference between polymer A in the polymer material layer and material B in the material layer with a refractive index difference from the above polymers is 0.7 to 1.

5.

3. The colorimetric sensor according to claim 1, characterized in that: in the polymer material layer, polymer A is polyisoprene, and in the material layer with a refractive index difference from the above polymers, material B is titanium dioxide.

4. The colorimetric sensor according to claim 1, wherein: the assembly period of the polymer material layer and the material layer with a refractive index difference from the above polymers is 3 to 5.

5. The colorimetric sensor according to claim 1, wherein: the hydrophilic treatment method is to place the silicon wafer in deionized water and heat it to 50 to 180 °C, add a mixed solution of hydrogen peroxide and ammonia water and treat it for 1 to 60 min. Among them, the volume ratio of hydrogen peroxide to ammonia water in the mixed solution of hydrogen peroxide and ammonia water is 10:1 to 50, and the volume ratio of deionized water to the mixed solution of hydrogen peroxide and ammonia water is 10:1 to 20.

6. The colorimetric sensor according to claim 1, characterized in that: the thickness of the silicon substrate is greater than 1 mm; the sum of the optical thicknesses of each assembly period of the one-dimensional photonic crystal film is 100 to 300 nm.

7. The preparation method of the colorimetric sensor according to any one of claims 1 to 6, characterized in that: ① Plasma-treat the silicon substrate for 30 s; ② Prepare a polymer dispersion; ③ Prepare a dispersion of a material with a refractive index difference from the above polymers; ④ Spin-coat the polymer dispersion obtained in the above step ② on the silicon substrate, adjust the spin-coating conditions to control the film thickness, heat and dry it, and then continue to spin-coat the material dispersion obtained in the above step ② on the dried material, adjust the spin-coating conditions to control the film thickness, heat and dry it. The above steps are repeated 0 to 15 times to obtain the product.

8. The preparation method according to claim 7, characterized in that: the mass fractions of the polymer dispersion and the dispersion of the material with a refractive index difference from the above polymers are both 0.5% to 20%.

9. The preparation method according to claim 7, wherein: the heat-drying conditions are heating at 30 to 200 °C for 1 to 60 min.

10. The application of the colorimetric sensor according to any one of claims 1 to 6 in detecting gasoline gas.

Images