This study concerns the development of a maghemite (γ-Fe2O3)-coupled tetra sulfophenyl porphyrin (TSPP) thin film–based optical waveguide (OWG) sensor (TSPP-γ-Fe2O3-OWG) for the detection of ethylenediamine (EDA). For ease of manufacture, we fabricated sensors using a spin-coating technique, and characterized their response based on their ultraviolet-visible (UV-vis) absorption spectra and the response intensity of OWG sensor. We have observed significant changes in the location of the peaks in the sensor’s UV-vis absorption spectra after exposed to EDA gas, indicating aggregation of TSPP. Optical characterization confirmed that the combination of TSPP with maghemite (TSPP-γ-Fe2O3-OWG) had improved device response, with twice as high as those of the acid-treated TSPP-OWG sensor, and 30 times higher than that of the pure γ-Fe2O3-OWG sensor. At ambient temperature, the composite sensor exhibited a linear response to EDA gas in the concentration range of 0.1–1000 ppm with signal-to-noise ratio (S/N) 8.33, confirming that the improved stability of the composite TSPP-γ-Fe2O3 thin-film OWG enables the detection of trace amounts of gas with high sensitivity and selectivity.
In this work, the metalloporphyrin film of PtOEP/Poly (St-co-TFEMA) modified by nano Al 2 O 3 powder was prepared, and the enhancement performance of oxygen sensing was studied in detail. It was verified that the modified film extended the residence time of oxygen through the characterization of SEM. The phosphorescence intensity changes with the content of Al 2 O 3 and PtOEP were studied. The Stern-Volmer equations before and after modification of Al 2 O 3 powder was compared. It was found that the linearity of the calibration curve was still high, but the oxygen sensitivity value of K SV was significantly improved due to the increase of quenching probability between indicator and oxygen. Finally, the stability test shows that the Al 2 O 3 @PtOEP/Poly (St-co-TFEMA) oxygen sensing film presents a strong anti-photo-bleaching ability, and the response time is shortened.