Comparative Studies on Sensitivity and Stability of Fiber-optic Oxygen Sensor Using Several Cladding Polymers

Abstract

An attempt has been made to improve the sensitivity and stability of the polymer optical fiber (POF) sensor for continuous monitoring of gaseous oxygen. It utilizes the quenching phenomenon of cladding fluorescence. Three polymers namely, poly(cyclohexyl methacrylate) (PCMA), poly(l-menthyl methacrylate) (PMtMA) and poly(4-methyl-1-pentene), which have a relatively large oxygen permeability, were used as cladding layer doped with a sensitive dye such as a 9,10-diphenyl anthracene (DPA), on the polymer cores with 1 mm diameter. When these sensor heads were pumped using a D2-lamp, the response at the fluorescence of λ=431 nm was found to be very fast and reversible in all the cases, for oxygen concentrations ranging from 0.5% to 100%. However, the differences in fluorescence quenching rate, stability and response time were observed to be dependent upon the polymer used. In particular, the PCMA sample showed good long-term stability. These comparative studies of POF oxygen sensors seem to be useful for developing practical devices.