Research On Optical Fiber Photothermal Sensor For Antibiotic Detection In Water

As an emerging water quality contaminant,antibiotics not only endanger the ecological balance,but also enter the human body with the food chain,damaging the immune system,causing allergic reactions,toxic reactions,and in serious cases,permanent damage.Therefore,there is an urgent need to study a highly sensitive and rapid detection technique that can be used for the detection of antibiotic contaminants in water.Fiber optic sensing technology has been widely used in the field of environmental detection because of its advantages such as high sensitivity,field detectability,chemical resistance,and environmental friendliness.Photothermal technology detects only the absorption of biomolecules,effectively avoiding the interference of light scattering and reflection,with excellent selectivity.In this thesis,oriented to the detection of antibiotics in water,the strong adsorption property of two-dimensional materials and the photothermal effect of molecules are combined to study a high-performance optical fiber sensor.By analyzing the response of the sensor in the presence of changing pollutant concentrations,high-sensitivity detection of antibiotics in water was achieved,providing a new research idea for the detection technology of trace substances in water.The main research contents of this thesis are as follows:1.The preparation methods and sensing principles of different fiber optic structures are described.Several methods of microfiber preparation are described in detail and the transmission mechanism of several fiber structures are analyzed theoretically.2.The working principle of photothermal interferometry was introduced and combined with fiber optic sensing technology to propose and implement a no-core fiber coupler and a few-mode fiber coupler for streptomycin sulfate concentration detection.The experimental results show that the Nb₂CTx integrated few-mode fiber coupler has higher sensitivity with a detection sensitivity of 210.66 nm/（mg/ml）,which is 1.6 times higher compared with the uncoated.3.Combining Ti₃CN/PDMS and the photothermal effect of molecules,three optical fiber sensors for Oxacillin sodium detection were proposed and their sensing performance was experimentally investigated.The experimental results showed that the sensitivity of Ti₃CN/PDMS composite coated microfiber was-761.39 nm/（mg/ml）,which was six times more sensitive than the uncoated microfiber sensor,with a low detection limit of 26 ng/ml.