Adjustment Of Sensitivity Of Room Temperature Phosphorescent Oxygen Measurement And Wide Range High Precision Oxygen Sensing

Oxygen is not only widely available,but also widely used.In some areas,oxygen needs to be monitored,utilized and controlled.Accurate measurement of oxygen is essential to our production and life.In recent years,the optical method based on room temperature phosphorescent oxygen quenching has gradually replaced the traditional electronic sensing and become a powerful oxygen sensing technology.However,room-temperature phosphorescence is easily quenched by oxygen in the surrounding environment,leading to large error and inaccurate measurement of high concentration oxygen,which makes the oxygen measurement range of room-temperature phosphorescence oxygen sensing system limited.Therefore,it is necessary to find a method to increase the range of oxygen measurement by phosphorescence at room temperature.In this paper,the optical properties and oxygen sensing ability of the oxygen sensing film based on the room temperature phosphorescence oxygen quenching principle are studied,as well as the ways to adjust the oxygen quenching constant and the relative sensitivity of oxygen measurement.The oxygen sensing performance and sensing stability of a double emission ratio oxygen sensing membrane based on oxygen sensitivity and oxygen inertia were studied.Fluorinated copolymer was synthesized with toluene as solvent by thermal solvent method.Fluorinated copolymer was proved to be an excellent probe carrier matrix by fluorescence spectrum,contact Angle measurement and SEM.A ratio type oxygen sensing film with a thickness of 4μm has been successfully prepared.The oxygen sensing performance and sensing stability of the film have been studied.The measurement results show that the film has good oxygen sensing performance,and the oxygen quenching constant K_SVis 0.32 kpa^-1.It is found that the relative error of oxygen measurement increases with the increase of oxygen concentration when the oxygen concentration is greater than 10%.The regulating ways of oxygen quenching constant and relative sensitivity of oxygen sensing membrane were studied.Firstly,the regulation mechanism of relative sensitivity and oxygen quenching constant is described.Secondly,the relative error analysis of room temperature phosphorescent oxygen measurement is described in detail,and the cause of inaccuracy of oxygen measurement in the range of high oxygen concentration is found.Finally,three methods of adjusting the oxygen quenching constant are given.It was found that K_SVcould be adjusted best by the combination of different probes and different substrates,and the adjustment effect could reach a numerical change of 250 times.The research of the adjustable wide range high precision oxygen sensor is carried out.Firstly,the relationship between SNR of phosphorescent signal and K_SVis studied.The results show that the SNR of the phosphorescent signal measured by the detector has a cubic polynomial relationship with the intensity of the original signal.Secondly,the variation relationship between the oxygen measurement S_rand K_SVwas studied.It was found that the smaller K_SVvalue was,the smaller the oxygen measurement S_rwas,and the decrease degree of S_rwith the increase of oxygen concentration was also slower.Finally,the theoretical idea of the adjustable wide range and high precision oxygen sensor is described in detail,and its experimental verification is conducted.Theoretical and experimental results show that the optimal oxygen measurement range changes with the change of K_SVof the oxygen sensing film.In this paper,a four-gear oxygen sensing system is designed,which can accurately measure oxygen from 0.2 k Pa to 100 k Pa in a wide range,and the relative error of measurement is less than 1.5%.