An Ambient-Insensitive Battery-Less Wireless Node for Simultaneous Powering and Communication

This work proposes a new multi-layer architecture for a compact, battery-less sensor node specifically designed to be robust and functional in environments hostile to the electromagnetic propagation, as is the case of the automotive and the industrial sectors. The goal is to enable real time monitoring of difficult-to-be-reached engine parts, to prevent and/or register possible malfunctioning, failure or unwanted warming of the tagged components. In order to enable simultaneous powering and communication, the LoRa (Long Range) protocol has been adopted in the 2.4 GHz frequency band and a RF power source has been used in the same band. A miniaturized, high-efficiency rectenna, designed to be directly in contact with the metallic parts, is used in combination with a power management unit to enable cold-start operations of the sensor. Measurements conducted inside a car engine show that the node is activated in less than 300 seconds with a RF power source located at 54-cm distance.