Sensing and communication potentialities of coupled RFID tags

The upcoming Internet of Things is realizing the vision of a fully connected world: one of the key enablers for such technological revolution is the development of low-cost long-lasting sensors, able to become the physical interface to the real-world. In such a quest, the Radio Frequency Identication (RFID) is establishing itself as the most promising technology for passive sensing, thanks to its standardized communication protocol and its massive use in nowaday's logistics, which has driven down the costs of commercial components. The extensive research eort of the latest years on the topic has achieved remarkable results, but there are some open issues that still inhibit a full adoption of the technology, among which the current sacrice in communication capability experienced along with the sensing process. The present Work tries to tackle the current issues, by investigating the potentialities of using two or more coupled RFID tags and exploiting the mutual interaction between them to enable better solutions to the present questions. Both theoretical and experimental aspects will be considered: the mathematical formulation will show the eects of the interaction between tags, highlighting the potentialities in terms of concurrent sensing and communication, and also exhibiting new and visionary capabilities of communication from tag to tag. The design of a specic sensor (a crack enlargement sensor) as well as the analysis and synthesis of a generic wireless sensing platform based on RFID couplets will be presented, exhibiting the desired properties of stable communication during the sensing process. Moreover, suitable sensing parameters and advanced measurement techniques will be introduced, allowing for improved sensitivity and measurement-setup independence. Finally, the experimental part will provide a better insight into some possible applications of RFID grids, as sketched in the theory, and will demonstrate practical implementations of the proposed functionalities.