Chipless and Batteryless Microwave Sensor Cell for Remote Detection of Humidity

Chipless Radio-Frequency IDentification (RFID) sensors belong to the class of microwave sensors and are a quite innovative sensing solution which provide an added value to sensors operating in an Internet of Things/Everything (IoT/E) era. Research is currently focused in two main directions: studying of the material properties as a function of the transduction mechanism and improving the robustness in the transmission mechanism. Here, the aim is to prove the properties of a sensor prototype based on the Nafion NRE-212 50μm-thick sensitive material, in terms of sensitivity, accuracy, reversibility and real-time response/recovery when the sensor is interrogated wirelessy by a suitable reader. Compared to other sensitive materials for humidity detection, Nafion is comparable in terms of sensitivity to polyvinyl-alcohol (PVA) and paper, but with a real-time response/recovery trends.