Optimizing Production Conditions for a Composite Optical Oxygen Sensor Using Mesoporous SiO2

Abstract

This paper reports on the creation of a new composite sensor material for detecting molecular oxygen, in which the fluorescent indicator, Pt (II) 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)-porphyrin, is adsorbed on mesoporous silica particles distributed in a fluorinated polymer performing the functions of the gas transmission line and protection against leaching. A set of methods is used to determine the optimal conditions for the monolayer adsorption of the dye. It is found that unwanted multilayer adsorption with the formation of dimers begins when the ratio of the diameter of the average adsorption center to the average diameter of the indicator molecule is less than three. An original method is applied for the encapsulation of microparticles with the formation of a surface salt of fluorinated surfactants, which protect the material at the manufacturing stage before its deposition to the substrate. It is shown that the material has a linear calibration dependence in a range from 0 to 40°C, a response time in the gas phase of less than 10 s, and photostability sufficient to function as an oxygen sensor for at least a year.