Tag testing methodology for RFID enabled temperature tracking and shelf life estimation

Recent advances in sensory devices using radio frequency identification (RFID) led to applications such as monitoring the temperature during the transportation of heat sensitive products where recorded data can be used to detect refrigeration equipment failure along the supply chain or estimate remaining shelf life of the product. For the project discussed in this paper, a handheld based portable RFID system is used to track the storage and transportation temperatures of perishable products using battery assisted passive temperature tags. The information from the tags is used in shelf life prediction models to estimate the remaining shelf life based on the recorded temperature data to provide a dynamic expiration date. Instead of the full application development effort, this paper focuses on the unique project requirements and challenges which led to the introduction of three novel concepts related to RFID enabled temperature tracking systems. First, due to absence of a common standard for testing RFID temperature tags, we develop a requirement driven, comprehensive testing protocol combining statistical tools and common industry standards with the help of a uniquely designed test setup to realistically simulate and evaluate the real life performances of different temperature tags. Next, a novel context based accuracy metric is derived for objective and application (such as shelf life prediction) specific comparison of different technologies. Finally, a pallet temperature estimation algorithm is developed to overcome some of the physical difficulties encountered in reading ultra-high frequency tags near the presence of metals and liquids.