Portable optical oxygen sensor based on Ru(II) complex and dye entrapped core-shell nanoparticles embedded in sol-gel matrix coated on a photodiode

A simple low-cost technique for the fabrication of portable optical oxygen sensors is described. The sensing film is based on the oxygen sensing dye tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) {[Ru(dpp)3]^{2 +}} and dye-entrapped core-shell silica nanoparticles embedded in a sol-gel matrix. The feasibility of coating a photodiode with the oxygen sensing film to fabricate a portable optical sensing device is investigated. The sensitivity of the sensor is quantified in terms of the ratio IN2/IO2, where IN2 and IO2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the portable optical oxygen sensor has sensitivity of 41. The sensor exhibits a linear response for oxygen concentrations in the range 0 to 60%. A preparation procedure for coating photodiodes with the oxygen film that produces repetitive and reliable sensing devices is proposed. The developed optical oxygen sensor is portable, low-cost, highly sensitive, and lacks optical filter elements. The proposed sensor is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optically based sensors.