Evaluation of sensor readability and thermal relevance for RFID temperature tracking

Radio frequency identification (RFID) offers a way to satisfy the current needs of the produce industry for product identification and cool chain preservation. The main challenges for RFID temperature tracking in produce cool chain monitoring are the produce's high-water content and the cost. Water absorbs radio frequency energy decreasing read range and limiting sensor placement. Whereas cost limits the number of sensors that may be used in a viable system. Therefore, the minimal number of sensor placements that maximize the representation of the temperatures of the product in pallets of high-water content produce must be determined. The objectives of the research presented in this paper were: To identify a location able to represent 85% of the temperatures present in a pallet of bottled water mimicking produce when subjected to heating and cooling conditions similar to the loading–unloading process. And second, to assess the readability and read range of a commercially available RFID battery assisted passive tag in this thermally relevant position so as to determine whether it would be read at the required distance for the supply chain. A single location representing 85% of the temperatures in the pallet was not found; consequently, it was suggested using a location with a temperature that would 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 and read range in this position vary 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.