阅读说明：本技术 一种石墨烯量子点复合材料光纤气体传感器制作方法 (Manufacturing method of graphene quantum dot composite material optical fiber gas sensor ) 是由 黄国家 李茂东 杨波 冯文林 杨晓占 陈翠 翟伟 李仕平 郭华超 李爽 于 2019-10-29 设计创作，主要内容包括：本发明公开了一种光纤气体传感器的制备方法,其中该光纤传感器为由第一单模光纤、第一多模光纤、光子晶体光纤、第二多模光纤、第二单模光纤构成,光子晶体光纤两端分别连接第一多模光纤和第二多模光纤,第一多模光纤及第二多模光纤两端分别熔接有第一单模光纤和第二单模光纤,光子晶体光纤表面涂覆有二氧化钛/氨基化石墨烯量子点复合敏感膜；制备方法包括制备二氧化钛/氨基化石墨烯量子点复合材料及将其涂覆于光子晶体光纤上,形成检测膜并将多段光纤熔接形成干涉仪。本发明的石墨烯量子点复合材料光纤气体传感器制作成本低,体积小,结构简单,稳定,易于制备。(The invention discloses a preparation method of optical fiber gas sensors, wherein the optical fiber sensors are composed of single-mode optical fibers, multi-mode optical fibers, photonic crystal optical fibers, second multi-mode optical fibers and second single-mode optical fibers, two ends of each photonic crystal optical fiber are respectively connected with multi-mode optical fibers and the second multi-mode optical fibers, two ends of each multi-mode optical fiber and the second multi-mode optical fibers are respectively welded with single-mode optical fibers and the second single-mode optical fibers, and the surface of each photonic crystal optical fiber is coated with a titanium dioxide/aminated graphene quantum dot composite sensitive film.)

The preparation method of the optical fiber gas sensor comprises a single-mode optical fiber, a multi-mode optical fiber, a photonic crystal optical fiber, a second multi-mode optical fiber and a second single-mode optical fiber, wherein two ends of the photonic crystal optical fiber are respectively connected with an multi-mode optical fiber and the second multi-mode optical fiber, two ends of the multi-mode optical fiber and the second multi-mode optical fiber are respectively welded with a single-mode optical fiber and the second single-mode optical fiber, and the surface of the photonic crystal optical fiber is coated with a titanium dioxide/aminated graphene quantum dot composite sensitive film, and the method specifically comprises the following steps:

step 1: preparing a titanium dioxide/aminated graphene quantum dot composite material solution;

step 2: coating the prepared titanium dioxide/aminated graphene quantum dot composite material on a photonic crystal fiber to form a detection film;

and 3, cutting two ends of the coated photonic crystal fiber by using a fiber cutter, keeping the length of the photonic crystal fiber at 4.5cm, respectively welding two ends of the cut section with sections of multimode fibers in a taper welding mode by using a fiber welding machine, and then respectively welding two sections of multimode fibers with sections of single mode fibers.

2. The method for manufacturing the optical fiber gas sensor according to claim 1, wherein the step 1 is specifically: weighing 0.04g of nano titanium dioxide with the particle size of 5-10nm by using an electronic balance, dispersing the nano titanium dioxide in 50 ml of deionized water, preparing a nano titanium dioxide aqueous solution, adding a stirrer, and covering a preservative film;

stirring the mixed solution on a constant-temperature heating magnetic stirrer, taking 1 ml of the mixed solution in a small test tube by using a pipette, taking 1 ml of aminated graphene quantum dots with the concentration of 1mg/ml and the particle size of 2.5-4.5nm, mixing the aminated graphene quantum dots with the aminated graphene quantum dots, and putting the mixture in a mechanical ultrasonic cleaning machine for treatment; in the ultrasonic mixing process, the temperature is controlled to be lower than 4 ℃, and ultrasonic treatment is carried out for 20 minutes.

3. The method for manufacturing the optical fiber gas sensor according to claim 1, wherein the step 2 is specifically: fixing the photonic crystal fiber section in a suspended state, then placing the fixed photonic crystal fiber section into a vacuum drying oven for drying treatment, taking the optical fiber crystal fiber with the length of 7cm after drying, removing a coating layer by using an optical fiber wire stripper, and cleaning the optical fiber crystal; putting the sheared photonic crystal fiber on a clean glass slide, taking the prepared titanium dioxide/aminated graphene quantum dot solution by using a pipette, dropwise adding the solution on the fiber, dip-coating for 10 minutes, and taking out; repeating the fifth step for multiple times; placing the glass slide with the photonic crystal fiber in a vacuum drying box for drying; wherein the optimum drying temperature is 300 ℃ for 2 hours.

4. The preparation method of the optical fiber gas sensor according to claim 1, wherein the step 3 is specifically that the photonic crystal fiber is far away from the electrode to carry out two times of discharge, after times of discharge, the edge at the welding point is firstly welded, and the air discharged from the center due to the collapse of the air hole of the cladding of the photonic crystal fiber is captured to form an air cavity;

aligning the photonic crystal fiber and the th multimode fiber after the end face of the fiber is melted, advancing for a preset length, drawing back to complete the fusion splicing of the photonic crystal fiber and the th multimode fiber, and repeating the steps on the other end face of the photonic crystal fiber and the second multimode fiber until the drawing distance reaches a preset value.

Technical Field

The invention relates to the technical field of sensors, in particular to a manufacturing method of an graphene quantum dot composite material optical fiber gas sensor.

Background

Hydrogen sulfide (H)₂S) is colorless, extremely toxic and acidic gas, and even in the case of low concentration, human smell is damaged, so that low concentration H is prevented₂The monitoring of S is very important, and in the sensitive material, the functionalized graphene quantum dots are two-dimensional carbon materials with heterogeneous atoms/molecules contained in graphene and the aminated graphene quantum dots, namely nitrogen-containing groups modified on the surface to form bonds₂The contact area of S gas is large, so that H is adsorbed₂S gas is easier. The traditional hydrogen sulfide sensor has long detection response time and high manufacturing cost.

The optical fiber sensing technology is new high technologies with broad prospects in development, and because the optical fiber has a plurality of special properties in the process of information transmission, for example, the energy loss is very small when the optical fiber transmits information, which brings great convenience to remote measurement, the performance of the optical fiber material is stable, the optical fiber sensor is not interfered by an electromagnetic field, and the optical fiber sensor is kept unchanged in severe environments such as high temperature, high pressure, low temperature, strong corrosion and the like, develops at a rapid pace from the appearance to the present, therefore, how to manufacture gas sensors for detecting the concentration of low-concentration hydrogen sulfide by using the optical fiber sensing technology makes the sensors have the effects of stable work, good detection effect, fast effect time, high precision and reliability and the like, which becomes the problem needing to be considered in steps.

Disclosure of Invention

The invention aims to provide a manufacturing method of graphene quantum dot composite material optical fiber gas sensors, and aims to detect low-concentration hydrogen sulfide through the optical fiber gas sensors and improve detection accuracy and reliability.

In order to achieve the purpose, the invention provides the following technical scheme that the preparation method of the novel optical fiber gas sensor comprises a th single-mode optical fiber, a th multi-mode optical fiber, a photonic crystal optical fiber, a second multi-mode optical fiber and a second single-mode optical fiber, wherein two ends of the photonic crystal optical fiber are respectively connected with the th multi-mode optical fiber and the second multi-mode optical fiber, two ends of the th multi-mode optical fiber and the second multi-mode optical fiber are respectively welded with a th single-mode optical fiber and the second single-mode optical fiber, and the surface of the photonic crystal optical fiber is coated with a titanium dioxide/aminated graphene quantum dot composite sensitive film, and the method specifically comprises the following:

step 1: preparing a titanium dioxide/aminated graphene quantum dot composite material solution;

step 2: and coating the prepared titanium dioxide/aminated graphene quantum dot composite material on a photonic crystal fiber to form a detection film.

And 3, cutting two ends of the coated photonic crystal fiber by using a fiber cutter, keeping the length of the photonic crystal fiber at 4.5cm, respectively welding two ends of the cut section with sections of multimode fibers in a taper welding mode by using a fiber welding machine, and then respectively welding two sections of multimode fibers with sections of single mode fibers.

Compared with the prior art, the optical fiber gas sensor with the graphene quantum dot composite material has the beneficial effects that the photonic crystal optical fiber is coated with the titanium dioxide/aminated graphene quantum dot composite sensitive film, the titanium dioxide can effectively improve the sensitivity of the optical fiber sensor to hydrogen sulfide gas, the precision and the reliability of the optical fiber sensor adopting single graphene as the gas sensor are improved, and the movement of an interference wave peak is detected through a spectrum detector, so that the hydrogen sulfide gas can be detected.

Drawings

Fig. 1 is a schematic diagram of a method for manufacturing an optical fiber gas sensor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of linear fitting of wavelength shift and wavelength for detecting hydrogen sulfide gas with different concentrations according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only partial embodiments of of the present invention, rather than all embodiments.

The invention provides a preparation method of optical fiber gas sensors, wherein the optical fiber sensors are composed of single-mode optical fibers, multi-mode optical fibers, photonic crystal optical fibers, second multi-mode optical fibers and second single-mode optical fibers, wherein two ends of each of the photonic crystal optical fibers are respectively connected with the multi-mode optical fibers and the second multi-mode optical fibers, two ends of each of the multi-mode optical fibers and the second multi-mode optical fibers are respectively welded with the single-mode optical fibers and the second single-mode optical fibers, wherein layers of titanium dioxide/aminated graphene quantum dot composite sensitive films are coated on the optical surface of each of the photonic crystals, the method specifically comprises the preparation of a sensing element and the preparation of a titanium dioxide/aminated graphene quantum dot composite material, and comprises:

step 1: preparing a titanium dioxide/aminated graphene quantum dot composite material solution; the configuration process specifically comprises the following steps: weighing 0.04g of nano titanium dioxide with the particle size of 5-10nm by using an electronic balance, dispersing the nano titanium dioxide in 50 ml of deionized water, preparing a nano titanium dioxide aqueous solution, adding a stirrer, and covering a preservative film; stirring the mixed solution on a constant-temperature heating magnetic stirrer, taking 1 ml of the mixed solution in a small test tube by using a pipette, taking 1 ml of aminated graphene quantum dots with the concentration of 1mg/ml and the particle size of 2.5-4.5nm, mixing the aminated graphene quantum dots with the aminated graphene quantum dots, and putting the mixture in a mechanical ultrasonic cleaning machine for treatment; in the ultrasonic process, the temperature is controlled to be lower than 4 ℃, ultrasonic treatment is carried out for 20 minutes, the process is strictly sealed and is stored in a dark place, so that the titanium dioxide/aminated graphene quantum dot composite material is prepared;

the method comprises the following steps of (1) coating a prepared titanium dioxide/aminated graphene quantum dot composite material on a photonic crystal fiber to form a detection film, and specifically, fixing the photonic crystal fiber section in a suspended state, then placing the photonic crystal fiber section in a vacuum drying box for drying, taking a 7 cm-long optical fiber after drying, removing a coating layer by using a fiber stripping pliers, and cleaning the optical fiber section with alcohol, wherein the photonic crystal fiber section is fixed in a suspended state for drying to prevent the phenomenon of uneven film formation caused by horizontal placement, and in addition, steps can be carried out in the calcination process to enhance the adhesive force between the graphene material and the photonic crystal fiber section so that the graphene material and the photonic crystal fiber section are in a stable film structure and the structure of the photonic crystal fiber section cannot be damaged.

Putting the sheared photonic crystal fiber on a clean glass slide, taking the prepared titanium dioxide/aminated graphene quantum dot solution by using a pipette, dropwise adding the solution on the fiber, dip-coating for 10 minutes, and taking out;

repeating the fifth step for a plurality of times, preferably four times;

placing the glass slide with the photonic crystal fiber in a vacuum drying box for drying; drying at the optimal drying temperature of 300 ℃ for 2 hours to form the photonic crystal fiber coated with the titanium dioxide/aminated graphene quantum dot composite material;

step 3, utilizing an optical fiber cutter to cut two ends of a coated photonic crystal fiber flat, keeping the length of the photonic crystal fiber at 4.5cm, utilizing an optical fiber fusion splicer to respectively fuse the two ends of the cut section with sections of multimode fibers in a tapering fusion mode, then respectively fusing two sections of multimode fibers with sections of single mode fibers, wherein the photonic crystal fiber is far away from an electrode during fusion to discharge twice, after times of discharge, the edge of the fusion splice point is firstly fused and connected, air discharged from the center due to collapse of air holes of the cladding of the photonic crystal fiber is captured to form an air cavity, monitoring a reflection spectrum in real time, adding discharge for multiple times to maximize fineness and contrast ratio of reflection stripes, after the end face of the optical fiber is fused, aligning the cladding of the photonic crystal fiber with the multimode fiber and pushing a preset length, then pulling back to complete fusion of the photonic crystal fiber with the multimode fiber, repeating the steps of the photonic crystal fiber with another end face of the second multimode fiber until the end face of the photonic crystal fiber is fused and the cladding of the preset length is stretched to reach a preset value, in order to ensure that the optical fiber has low loss, the optical fiber has a better interference effect, the optical fiber fusion splice layer is formed by a better light absorption, and the fusion splice is formed before the fusion splice, the optical fiber is capable of forming a clean fusion splice layer, and the optical fiber is capable of forming a good optical fiber, the optical fiber, and the optical fiber, the optical fiber is capable of forming a good interference of a good interference light spectrum.

Photonic crystal fibers with different lengths are built into a Mach-Zehnder interference structure, and the number of interference wave peaks and interference peaks is observed through a spectrometer to confirm that the optimal interference effect can be found, so that the optimal length of the photonic crystal fiber of the gas sensor can be found. In the sensing structure, the longer the length of the photonic crystal fiber is, the more the number of the obtained interference peaks is, that is, the denser the interference peaks are, the shorter the length of the photonic crystal fiber is, the obviously reduced number of the obtained interference peaks is, and even the unsmooth peaks appear. The invention comprehensively considers the characteristics of proper wave crest quantity and less curve smooth burrs, and selects the optimal length of the photonic crystal fiber to be 4.5 cm.

The optical fiber hydrogen sulfide gas sensor prepared by the method detects hydrogen sulfide with different concentrations, such as H with the detected concentrations of 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm and 55 ppm respectively₂And S gas, collecting spectrograms of the hydrogen sulfide gas under different concentrations through a spectrometer, selecting the central wavelength of the same peak in the spectrograms, and obtaining p which is m-nc through linear fitting, namely c which is (m-p)/n, wherein p is the central wavelength of the peak in the detection spectrum of the hydrogen sulfide gas chamber, m is the central wavelength of the peak in the detection spectrum without containing the hydrogen sulfide gas, n is the offset of every 1ppm of the hydrogen sulfide gas in the spectrum and the sensitivity of the sensor, and c is the concentration of the hydrogen sulfide gas. As shown in FIG. 1, a peak at 1538.9nm in the output spectrum is selected for monitoring, the deviation condition of the peak along with the concentration of H2S gas within the range of 0-55 ppm is tested, and the output spectrum shows an obvious blue shift phenomenon along with the increase of the concentration of H2S gas. The titanium dioxide/aminated graphene quantum dot sensitive film in the sensing area adsorbs H₂The S gas molecules increase the refractive index of the cladding, so that the difference between the effective refractive indexes of the fiber core and the cladding is increased, the central wavelength is subjected to blue shift, and the experimental result is consistent with the theoretical analysis. The sensitivity of the sensor to hydrogen sulfide was calculated to be 26.62pm/ppm and the linearity was 0.99249 by means of the above linear fit over the range of 0-55 pp hydrogen sulfide concentrations. The experimental result shows that the sensor pair H₂S has high selectivity.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.