Application of new matrix materials for dissolved and gaseous carbon dioxide sensing and fiber optic carbon dioxide sensor design

In most of the optical carbon dioxide sensor designs, pH probes with different absorption or emission maxima were embedded in a polymer or sol-gel matrix material. Immobilization of the dye in the matrix material effectively induces spectral characteristics of the sensing agent. In this work, polyvinyl chloride, ethyl cellulose and polymethylmethacrylate were used together with different types of additives for carbon dioxide or dissolved carbon dioxide sensing purposes. Carbon dioxide carriers of perfluorochemicals or room temperature ionic liquids were employed and tested as polymer additives. Newly synthesized azomethine dyes were characterized by spectroscopic ways in thin film or micro fiber form in the polymer matrix materials. Quantum yield and acidity constant calculations of the azomethine dyes were performed in the conventional solvents and/or in the employed solid matrices. Their fluorescence based response to carbon dioxide or dissolved carbon dioxide were examined in flow systems with fiber optics. To our knowledge this is the first attempt to produce electrospun sensor fibers for carbon dioxide sensing purpose. The potential use of some of azomethine molecules as optical switches for the realization of artificial functions at the molecular level was also investigated. Their cross sensitivities to anions, metal cations and effect of ionic strength were tested. Except that of azomethine dyes, three potential fluorescence Schiff bases were also investigated for carbon dioxide and pH sensing in plasticized polyvinyl chloride and ethyl cellulose, with or without additives.Absorption and emission based spectral data and acidity constants of the schiff bases were determined in conventional solvents such as polyvinyl chloride and ethyl cellulose.