TagSense: Robust Wheat Moisture and Temperature Sensing Using a Passive RFID Tag

Driven by the fast increase of food demand world wide, the safety of grain storage becomes increasingly important. TWo key factors, i.e., temperature and moisture, greatly influence the safety of stored grain. The traditional methods of detecting grain temperature and moisture are time-consuming, expensive, and inconvenient to use. In this paper, we develop a TagSense system for robust wheat moisture and temperature sensing using cheap commercial-off-the-shelf (COTS) RFID devices. We first validate the feasibility of using tag impedance for robust moisture and temperature sensing. We then propose a distance- free algorithm and an angle-agnostic method to mitigate the impact of different measurement distances and angles. Our experimental results demonstrate that the TagSense system can achieve satisfactory sensing accuracy of wheat moisture and temperature in different rotation angles and at different distances.