Effect of polymeric dye network bonding on fluorescence thermometry for optical fiber temperature sensor

Abstract

Fluorescein and two of its derivatives (allyl Fluorescein and diallyl Fluorescein) are solidified in glycidyl methacrylate (GMA) polymer matrix for the development of fluorescence-based fiber optically temperature sensor. These two Fluorescein derivatives were investigated in order to study the influence of degree of covalent bonds to GMA polymer backbone on Fluorescein dye sensitivity for temperature changes. The dye-polymer discs have been investigated separately in order to determine their sensitivities in the temperature ranges from 10 to 300 K and from 297 to 370 K. The dye-polymer discs are excited by Argon ion laser (488 nm, 50 mW) and the fluorescence intensity is measured using lock-in technique. Below room-temperature Fluorescein dye in (GMA) polymer shows very weak sensitivity toward temperature changes in the range from 10 up to 297 K. The fluorescence intensity peaks of allyl Fluorescein dye in (GMA) polymer exhibit tendency for decreasing slightly, while the dye is warmed up from 40 to 245 K. Also, the fluorescence intensity peaks of diallyl Fluorescein dye in (GMA) are reported in the temperature range from 49 to 300 K. The intensity peak values decrease gradually, whereas at the temperature 171 and 229 K the peaks show hazard change. Above room temperature, the fluorescence intensity peaks decrease with increasing temperature in the temperature range from 302 to 370 K.