Self-Powered Multi-Port UHF RFID Tag-Based-Sensor

In this paper, multi-port UHF RFID tag-based sensor for wireless identification and sensing applications is presented. Two RFID chips, one with attached sensor and the other without, are incorporated in a single tag antenna with two excitation ports. The chip with the integrated sensor (sensor port) transmits a signal impacted by the sensed temperature or humidity, while the other RFID chip serves as the reference signal (reference port) transmitter in the sensing process. The proposed tag-based sensor is fabricated and experimentally evaluated. The measured results demonstrate that the sensed data can be extracted using a commercial RFID reader by recording and comparing the difference in the reader output power required to power up the reference port and the power required to power the sensor ports. To improve the reading range of the proposed sensor, a dual-port solar powered RFID sensor is also presented. The reading range of the sensor is increased by two times compared to a similar prototype without solar energy harvesting. The experimental evaluation demonstrates that the proposed tag-based sensor can be easily integrated with a resistive humidity or temperature sensor for a low-cost solution to detect the heat or humidity exposure of sensitive items for several applications such as supply chains and construction structures.