Design and integration of low power RFID wake-up radio for the activation of sensing nodes in industrial plants

Hybrid wireless sensing nodes, composed of different sampling/processing and communication interfaces are gaining increasing interest in industrial scenarios thanks to their capability to create sensing networks with limited impact on operational costs and architectures. In this paper, the authors present the design and characterization of a Radio Frequency IDentification (RFID) board for the on-demand activation of sensing nodes. The device resorts to the functionalities of the EM4325 RFID IC which can emit simple voltage transitions upon the reception of RF events to wake up an external device. The antenna, namely a coplanar F-antenna, fulfills the design constraints due to its application in a potentially explosive environment and achieves a realized gain of 4 dBi. The latter, combined with the extremely low power sensitivity of the IC configured in semi-active mode, grants a reading distance of approximately 10 m. The potentialities of the IC are then investigated by comparing two configurations of the IC in terms of the duration of the wake-up signal and thus power consumption. The findings indicate that the most selective configuration is the most indicated choice in case of limited power sources.