Research On Key Technology Of Optical Fiber Dissolved Oxygen Sensor Based On Fluorescence Quenching Principle

The measurement of dissolved oxygen（DO） content is of great significance.In aquaculture,low dissolved oxygen levels can make it difficult for aquatic organisms to breathe and even kill them.Dissolved oxygen in cell growth of human and animal tissues plays an important role.Cellular metabolism and other life activities require the participation of dissolved oxygen.For cell proliferation,Oxygen content is also an important parameter.Measuring dissolved oxygen content is equally vital for ocean exploration.In order to measure the dissolved oxygen in the liquid,which is required to be light,small,low cost,and does not consume oxygen at the same time.The optical fiber dissolved Oxygen sensor experiment is carried out.As a photoluminescence phenomenon,the generation of fluorescence is closely related to the molecular structure of the substance.The fluorescent material is usually a substance with high fluorescence quantum emission efficiency.In this paper,platinum octaethylporphyrin（PtOEP） is used as fluorescent material.The phenomenon of fluorescence quenching refers to that the excited state molecules interact with other molecules（quencher molecules）,resulting in a decrease in fluorescence lifetime and a decrease in fluorescence intensity.The fiber-optic dissolved oxygen sensor introduced in this paper is based on the principle of fluorescence quenching.Under excitation light,the generated fluorescent molecules interact with oxygen molecules（quencher molecules）.And the energy of the fluorescent molecules is transferred to the oxygen molecules.Resulting in a decrease in the luminous intensity value of the fluorescent molecule and a shortening of the life.Fiber optic dissolved oxygen sensors based on the principle of fluorescence quenching have always been focused by many research works.This paper introduces a simple and low-cost method to make fiber optic oxygen sensor.The technology is based on the principle of fluorescence quenching,that is,the fluorescence material is platinum octaethyl porphyrin（PtOEP）,which is coated on the fiber end.In this sensor,the fluorescent material is excited by violet light of 395 nm and guided by Y-shaped optical fibers.The generated fluorescence is input to the spectrometer through the other end of the Y-shaped fiber.The value of PtOEP I₀/I₁₀₀-1 is 0.78.That is to say,the sensitivity of the sensor studied in this paper is 0.78,and the linear correlation coefficient of the Stern-Volmer graph is 0.94,showing good linearity.The response time from the air environment to oxygen is 5 s.And the response time from the oxygen to air environment is 24 s.These results show that the fiber optic oxygen sensor based on fluorescence quenching principle has higher sensitivity and faster response time.Finally,the oxygen content in the tissue fluid of 3T3 cells is measured using the self-made sensor.And the oxygen content measured in the tissue fluid is 15.40 mg/L.