Layer-by-Layer assembly of a water-insoluble platinum complex for optical fiber oxygen sensors

An optical fiber sensor to measure gaseous oxygen is presented in this work. The device is based on platinum tetrakis pentrafluorophenyporphine (PtTFPP), a reagent that shows a luminescence at 650 nm when it is illuminated at 390 nm. The emitted signal decreases as oxygen concentrations increases. This sensing material is deposited onto a cleaved-end plastic silica cladding (PCS) fiber by means of the Layer-by-Layer method (LbL). The experimental set up has been also optimized in terms of the dimensions of the optical components in order to get the highest signal level. The response of the sensor has been studied in terms of different oxygen concentrations as well as dynamic conditions. The resulting sensor shows a reversible and linear behavior for oxygen concentrations from 0% up to 100% (R² = 0.9991). The initial inconvenience derived by the non-water solubility of PtTFPP and its challenging deposition by LbL has been overcome by preparing an emulsion.