A fiber optic temperature sensor with an epoxy-glue membrane as a temperature indicator

A fiber optic temperature sensor for monitoring/detecting ambient temperature ranging from room temperature (25 °C) to ∼100 °C has been described. This sensor uses polycyclic aromatic compounds (PAHs) presenting in a commercially available epoxy glue as the temperature indicator. The PAHs in the epoxy glue fluoresce when excited with a UV light source. The intensity of the fluorescence of the PAHs decreases when the epoxy glue is exposed to an environment of higher temperature. Therefore, the reduction of fluorescence signal can be used to indicate temperature. A simple structured optical fiber temperature transducer has been constructed by gluing two silica optical fibers together with the epoxy glue. An optical fiber temperature sensor was built up by connecting one of the fibers to a UV light emitting diode and the other fiber to an optical fiber compatible UV–vis spectrometer. The sensor has been tested for monitoring temperature from room temperature up to 100 °C. The attenuation of the fluorescence intensity of the fiber optic sensor in dB has a linear relationship with temperature in the tested range. In this paper, the principle, fabrication, response characteristics, calibration, stability of this sensor and possible applications of the temperature sensing principle established in this work are discussed.