Optimization of ormosil glasses for luminescence based dissolved oxygen sensors

In the recent years, sol-gel films have been intensively used in optical sensors configurations. Due to its hydrophobic nature, ormosil films have been reported to be a promising supporting matrix for oxygen sensing dyes for measurements in aqueous media. In this work, the impact of the sol-gel host fabrication parameters in the characteristics of the resulting oxygen sensing membranes is thoroughly evaluated. Different combinations of organic-inorganic precursors, with different aging times, were tested as oxygen sensors. All the solution were doped with ruthenium complex Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline) to introduce oxygen sensitivity. Thin films were produced by dip coating of glass slides. The oxygen sensitive films were tested in aqueous phase in equilibrium with different oxygen gas compositions, using a phase-modulation technique. Sensor performance parameters such as Stern-Volmer constant, quenching efficiency and lifetime response are reported. The data obtained clearly indicates that increased aging times and longer organic groups produce sensors with the highest sensitivity to dissolved oxygen. From all sol-gel films produced, the BTEOS:TEOS (1:1) mixture is the most promising for sensor construction.