Multifunction fiber optic sensing system for smart applications

The end of the twentieth century was witness to the merger of several technological disciplines that could eventually revolutionize engineering design philosophy and lead to the creation of intelligence within otherwise inanimate structures. This new technology will endow a structure with senses and the ability to react to its environment and change its state, shape and geometry. The key point for the practical realization of the so-called smart materials is the availability of robust and reliable structurally integrated sensors able to monitor the state of the structure. To this aim, a fiber optic multiparameter sensing system for process and structural health monitoring in concrete structures is presented. The reflectometric technique has been implemented for refractive-index measurements by using as transducer the fiber end/host interface. Results on the capability of the developed sensor to monitor the curing process of thermoset-based composites are presented. The integration with fiber Bragg gratings (FBGs) with the aim to perform temperature and strain measurements has been discussed. Two low-cost intensity-based demodulation techniques for FBGs interrogation have been developed and tested.