A new portable optical sensor for dual sensing of temperature and oxygen

A new simple, low-cost technique for the fabrication of a portable optical sensor for the dual sensing of temperature and oxygen is described. The sensing film is based on the oxygen sensing dye platinum tetrakis pentrafluoropheny porphine (PtTFPP) and 7-amino-4-trifluoromethyl coumarin (AFC) embedded in tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS) composite xerogels. The feasibility of coating a color sensor with the sensing film to fabricate a portable optical dual sensing device is investigated. The temperature and oxygen indicators can both be excited with an LED at a wavelength 405 nm. The portable optical dual sensor has been tested with regard to monitoring different temperatures and oxygen concentrations, the oxygen response of which is quantified in terms of the ratio IN2/IO2IN2/IO2, where IN2IN2 and IO2IO2 represent the detected phosphorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental results reveal that the portable optical oxygen sensor has a response of IN2/I100O2=1.75IN2/I100O2=1.75. In addition, our results show that the luminescence properties of the temperature sensor are independent of the presence of the oxygen sensor, and have a uniquely good linear response in the 25–65 °C range. Finally, the oxygen sensing scheme presented in this work is intended for use in temperature compensation, and the portable optical dual sensor is a cost-effective alternative to traditional electrochemical-based temperature and oxygen sensors and provides a platform for other optically based sensors.