Research On The Fluorescence Sensing Technology Of Liquid-core Hydrogel Optical Fiber

In recent years,with the country’s attention to ecological and environmental issues,people’s demand for the detection of small molecular pollutants has increased.Miniaturized and integrated optical fiber fluorescence sensors have become an ideal choice for the real-time detection of small molecular pollutants.As the core component of optical fiber fluorescence sensors,the design and preparation of optical fiber fluorescence probes are very important.However,the existing optical fiber fluorescent probes are faced with the problems of complicated preparation processes,low sensitivity,and non-recycling which seriously restrict the application and development of optical fiber fluorescent sensors.In view of the limitations of the existing optical fiber fluorescence probes,a novel liquid-core hydrogel optical fiber fluorescence probe is proposed in this paper,and a miniaturized optical fiber fluorescence sensor is constructed,which realizes the detection of mercury ions(Hg²⁺).The main work of this thesis is as follows:（1）Preparation and properties of liquid-core hydrogel optical fiber.A hydrogel optical fiber structure of"liquid core-hydrogel fiber core-hydrogel cladding"was proposed.Through the characterization of the flexibility,refractive index and swelling ratio of the hydrogel optical fiber,the optimal concentration of 40%hydrogel core monomer is determined.At the same time,through the methods of software simulation and optical loss measurement,the optical field distribution and light transmission performance of hydrogel fiber is analyzed and evaluated.（2）Design and construction of a liquid-core hydrogel optical fiber fluorescence sensor.A liquid core hydrogel optical fiber fluorescence sensor based on smartphones was constructed.The hardware part is built with all-optical fiber.The integrated sensor is convenient for hand-held carrying and on-site detection.The size of the whole sensor is only 150 mm×180 mm×60 mm;At the same time,a smartphone detection APP was developed,which can realize the measurement of quenching rate and concentration detection.The preliminary test on the detection performance of the sensor proves that the sensor has good repeatability and stability.（3）The detection of mercury ions by quantum dots liquid core hydrogel optical fiber fluorescence sensor.The permeability of small molecules in the liquid-core hydrogel was studied.The sensor probe of the Cd Se/Zn S quantum dots liquid core was prepared,and the sensor was evaluated from the aspects of sensitivity,specificity,accuracy,actual environmental water sample detection,and reusability.The experimental results show that the detection limit of the sensor for Hg²⁺can reach 1n M,and it can be detected in the range of 1 nm-1μm.The sensor has good specificity and reusability and can be widely used in practical detection.