Today, Radio Frequency Identification (RFID) has become a multibillion-dollar industry. RFID is primarily used for numerous object tagging and tracking applications such as road toll collection service, facility access control, asset tracking in a supply chain to name a few. Batteryless tag architecture and modern fabrication technology has enabled the miniaturization and cost reduction of ultra-high frequency (UHF) passive RFIDs. There is growing interest in the use of RFIDs for supply chain sensors (e.g., agricultural products and pharmaceuticals), underground object tagging (e.g., plastic pipes), low-power wearable devices, etc. However, the RFID designs in their current form cannot meet the stringent requirements of these new applications. Four key challenges that hinders the direct adoption of existing RFIDs for these applications are: (a) clutter effect, (b) integration of sensors, (c) response time, and (d) prolonged RF transmission from RFID reader for continuous sensor monitoring. In this work, the fundamental limitations of conventional RFID system are described in detail first, followed by proposed solutions leading to new RFID designs. First, a dual frequency harmonic RFID system is proposed and demonstrated to mitigate the clutter effect. Second, a low power digital interface sensing platform is demonstrated for electrochemical pH sensor, targeted towards biochemical applications as an example. Third, detailed analysis is performed at the component level to understand the efficiency and response time dependence of the energy harvester within the RFID designs. Based on the analysis, a model was proposed to estimate the response time of a conventional RFID tag. Fourth, a dual mode RFID is proposed and demonstrated to reduce the transmit time of RFID reader, hence reducing the effective RF transmission. Furthermore, the compatibility of integrating these solutions together in a single platform are presented. This is important as more than one challenge can be present in a single application. Finally, a hybrid RFID configuration is proposed and demonstrated that is capable of simultaneously mitigating all these four challenges.
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