Evaluation of Sensor Readability and Thermal Relevance for RFID Temperature Tracking

Radio frequency identification (RFID) offers a way to satisfy the current need of the produce industry for product identification and cool chain preservation. Its application in cold chain monitoring has been studied and results have shown that RFID temperature tags have a superior performance than traditional temperature monitoring devices. The main challenges for RFID temperature tracking in produce are the produce’s high water content, which will affect the readability of the RFID systems and restrict the possibilities of sensor placement, and the cost of the tags, which will promote the minimization of the number of sensors being used. Therefore, the relevance of the temperatures recorded in them and the readability of the tags in these positions inside high water content loads are required to be studied. The objectives of this research were to find the temperature distribution inside a pallet of bottled water mimicking produce when subjected to heating and cooling conditions similar to the loading-unloading process, to identify a location able to represent 85% of the temperatures present on it; and to determine the level of readability of a commercially available RFID battery assisted passive tag in this thermally relevant position. Temperature differentials were found quite significant at the pallet level (up to 30 °C) and sometimes also at the primary package level. It was impossible to determine a single spot representing 85% of the temperatures in the pallet consequently; it is suggested to use a location with a temperature that will be the middle point of an interval that gathers the temperature readings of approximately 85% of the measured locations. In addition, results indicate that tag readability in this position varies depending on the configuration of the side of the pallet facing the antennas and the amount of air in the surroundings of the RFID tag.