Three-Port Zero-Power RFID Flood Sensor for IoT Applications

In this paper, a novel battery-less RFID based wireless sensor node is proposed. The proposed wireless sensor is completely passive and works by combining UHF RFID and a capacitance-based flood sensor. The capacitive sensor passively alters the phase of the backscattered RFID signal based on the level of the water. This phase change is easily detected at the receiver by a non-coherent IQ demodulator. The passive nature of this sensor avoids deteriorating the read range of a regular UHF RFID tag, making it ideal for home and industrial based applications.