Electromagnetic characterization of a food safe, organic smart material for customizable temperature threshold sensing in cold chain applications.

Temperature is an important parameter in cold chain applications and directly impacts the shelf life of perishable produce. Recently there has been much interest in using low-cost RFID tags for item level temperature threshold sensing in the cold chain. In this paper, we present the electromagnetic characterization of a composite oil made up of a mixture of two common cooking oils - grapeseed and coconut oil. We show how variations in the oil composition directly impacts the temperature at which the oil transitions from a solid to a liquid state. Moreover we show how this oil can be interfaced with a chipless RFID tag to create a low-cost, customizable temperature threshold sensor. We show how this sensor can be reliably used to detect threshold crossings of 4, 8 and 12°C, all of which are temperature ranges of interest in food monitoring. Avenues for future exploration and improvement are also discussed.