Assessment Of A Linearly Chirped Fiber Bragg Grating Sensor Under Linear And Non-Linear Temperature Gradient

Among several innovative procedures used in the fight against cancers, thermal treatments are gaining acceptance in clinical settings. In these approaches, heat is used to damage cancer cells. Therefore, it is useful to monitor the temperature reached in the tissue undergoing the treatment, in order to improve the outcome of the procedure.Despite the variety of available techniques investigated for temperature monitoring during thermal treatments, Linearly Chirped Fiber Bragg Grating (LCFBG) sensors can be seen as a good choice thanks to their small size, the flexibility of the fiber optic, as well as the immunity to electromagnetic interferences and the Magnetic Resonance- (MR-) compatibility.In this work a commercial LCFBG has been tested under different thermal gradients that typically occur during the thermal treatments (up to 30 degrees C). The sensor's response has been analysed under linear and non-linear thermal gradients. The shift and the width of the LCFBG's spectrum have been related to both the average temperature (T-mean) applied on its active area, and to the temperature difference (Delta T) experienced by the sensor between its two extremities. The analysis has showed promising results: actually with the sensor under test is possible to find a linear relationship between the spectrum shift and Tmean (with a sensitivity of about 10 pm degrees.C-1), and also between the spectrum width and the Delta T (5 pm degrees.C-1).These findings may allow extrapolating temperature information from the LCFBG spectrum, in order to monitor in real-time the effects of thermal treatment on biological tissue. Because the effects of thermal ablation depend on temperature, the knowledge of temperature may improve the treatments outcome, thus patient safety.