NFC-Powered Flexible Strain Gauge Data Logger for Monitoring Cracks in Built Cultural Heritage

Surface and structural cracks are among the most common problems that face structures and buildings. The problem is multiplicated in the case of buildings in built cultural heritage due to the delicacy of working in historically and culturally valued environments. In this work, we report on circuit modelling and the design of a novel crack detection and monitoring system using NFC technology for built cultural heritage preservation. The system revolves around a flexible strain gauge sensor that can be bonded to the surface of the structure under consideration. The applied tension and compression are transferred to the surface of the strain gauge through the bond line between the surface of the considered structure and the strain gauge. The captured data are conditioned, processed, and wirelessly transferred to the reader through an NFC tag. The system is wirelessly powered by a radio frequency energy harvesting circuit, which guarantees extended working operations and eliminates the need for attaching batteries with corrosive substances to the walls of culturally valued structures. The captured data by the sensing circuit can be accessed by NFC-enabled smartphones, tablets and notebooks, which makes the system suitable for IoT applications.