Two different fiber optic sensors were considered for use in ceramic cross flow filters. The intensity-based sensor was tested with a great degree of success. Even with a computerized data acquisition system, the intensity-based sensor was unable to achieve the resolution of the Fabry-Perot sensor. Another drawback of the intensity sensor is the hysteresis behavior observed over cyclic variation of temperature. We have determined that extrinsic Fabry-Perot fiber optic sensors can be used to measure thermal strains in ceramic cross-flow filters with accuracies of 0.1 {mu}m/m. The single ended approach of the reflective Fabry-Perot sensors is well suited for high thermal strain measurements; the results obtained show that the output of the fiber sensor tracks the temperature changes exactly as expected and shows no noticeable time lag between the measured and the output signal. Sapphire fibers were manufactured with silica claddings and their spectral attenuation was measured. An intensity based sensor using sapphire fibers was fabricated and its performance calibrated. The success of the Fabry-Perot sensor has proved that such fiber optic sensors are ideally suited for smart structures''in fossil energy applications. 11 refs., 43 figs.