RF-Enabled Flexible and Printed Electronics: A Route to Sustainable Wireless Sensors and Systems

This paper presents an overview of recent contributions to radio frequency (RF) or microwave-enabled, as opposed to RF-connected flexible electronics, as a route to enabling next-generation sustainable systems. First, RF-enabled means systems where RF technologies are not solely used for communication and connectivity. RF solutions for flexible and printable wireless power transfer (WPT) systems and rectennas are introduced, from 6.78 MHz to 40 GHz and micro-Watt to Watt-levels. Then, RF and antenna-based sensing solutions using soft, conformable, and functional materials are introduced, showing solutions based on advanced materials and sensing composites, as well as those exploiting natural material variations. Across the different case-studies highlighted, it is evident that flexible and printable RF electronics could not only match, but in some cases outperform, their conventional counterparts.