Optical Sensing of Dissolved Oxygen Using Dye-Doped Plastic Optical Fiber

Abstract

A new method for detecting dissolved oxygen in water is proposed here. The sensor is based on the enhancement of fluorescence yield by an interaction between tetoraphenylporphine (TPP) dye and oxygen molecules. In the presence of oxygen, when pumped by a He-Cd laser line of λ=441nm, it produced a strong fluorescence at around λ=656nm. The fiber-type sensor head was fabricated by cladding the fiber core (ARTON; n_d=1.51) with the poly-4-methyl-l-pentene polymer (PMP; n_d=1.47) doped with TPP. The experimental results indicated a good enhancement in the fluorescence for both oxygen gas and water dissolved oxygen (DO). The response was found to be linear and stable in the range of 100ppm- 1% for oxygen gas and lmg/l- 8mg/l for DO. The theoretical analysis and the sensor response for change in termperature are also discussed.