RF energy scavenger for battery-free Wireless Sensor Nodes

The continuous development of IoT (Internet Of Things) infrastructure and applications is paving the way to advanced and innovative ideas and solutions, some of which are pushing to the limit the state-of-the-art technology. The increasing demand of Wireless Sensor Nodes which need to be capable to collecting and sharing data wirelessly while often positioned in places hard to be reached and serviced, motivates engineers to look for innovative solutions of energy harvesting to allow battery-free sensor nodes. RF harvesting, due to the pervasiveness of RF energy, that can reach out of sight places, could be a key technology to power wirelessly IoT sensor devices, that in order to be ubiquitous, need to be wireless, maintenance free, battery free and low cost enough to be used almost anywhere. In this article will be shown the implementation of an RF energy transfer system for battery free wireless sensor nodes. The system comprises an RF power transmitter (used as Radio Frequency source) which delivers a power of 0.5 W at 868 MHz and an RF energy harvesting integrated circuit, IC (provided by STMicroelectronics) which is used as RF power receiver to power a battery-free sensor node. Experimental results will show how the system is capable to sustain a 10 mA load for a 50 ms acquisition time with the transmitted power delivered from several distances.