Embedded TDR wire-like sensing elements for monitoring applications

The present work describes two practical application scenarios for an innovative, diffused, low-cost sensing system, which can be permanently embedded in the system to be monitored (STBM), thus allowing the continuous, real-time monitoring over its whole life cycle. The basic idea of the considered sensing system is to endow the STBM with flexible, wire-like sensing elements (SE's), to be used in conjunction with time domain reflectometry (TDR). One of the crucial advantages of the proposed sensing system is that a SE could be tens of meters long; hence, one single SE may suffice to monitor large areas in a single shot. The two practical applications considered in this paper relate to moisture monitoring of building structures and to the management of irrigation in agriculture: for each of these application fields, preliminary experimental tests were performed, and the potential and limitations of the considered sensing system were assessed. Finally, in order to evaluate the metrological performance of the sensing systems, an additional set of experiments was carried out employing six different types of wire-like SE's and the obtained results were comparatively assessed