This paper presents the development of an optical fiber sensor for water content estimation in oil-water emul-sions. The sensor is based on the surface Plasmon resonance (SPR) principle applied in a polymer optical fiber (POF). For the sensor fabrication, a D-shape is performed on the POF to expose its core region, which has a gold thin film (nanometer thickness) for the SPR signal. The sensor is analyzed as a function of the water content in different emulsions conditions (from 0 to 55.5 M of water content), where a sensitivity of -0.0288 nm/M was obtained. In addition, the sensor presented a sensitivity of the transmitted optical power variation as a function of the water content. These results lead to the possibility of data fusion between optical power and wavelength responses to obtain a high accuracy in the water content estimation. In this case, a root mean squared error (RMSE) of 1.36 M was obtained on the emulsion characterization. As an important drawback in general sensors applications, the temperature cross-sensitivity was also analyzed, where a sensitivity of 0.118 nm/degrees C was ob-tained. Such temperature sensitivity of the sensor leads to errors in emulsion characterization as a function of the temperature. To address this issue, a compensation method based on direct difference between the sensor's sensitivities is proposed. By applying the proposed compensation method, a reduction of the temperature -induced errors in the water content estimation from 6.46 +/- 7.81 to only 0.32 +/- 1.96 .
展开▼
