A Three-Port Zero-Power RFID Sensor Architecture for IoT Applications

A novel zero-power wireless sensor architecture is proposed and demonstrated in this paper. The proposed wireless sensor, which is a passive sensor, combines UHF RFID and a capacitive sensor to enable reading of physical and chemical parameters wirelessly, without compromising much on the read-range, and complexity of conventional RFID tags. The sensor alters the phase of backscattered RFID signal, which is detected at the receiver using a non-coherent IQ demodulator. Due to the universal nature of this architecture, any type of sensor, such as temperature, humidity, water level sensor, can be realized. For the sake of simplicity, a varactor diode was initially used to get a thorough understanding of the system. Following that, a flood sensor was used to evaluate the performance of zero-power wireless sensor in a real-world application.