A broadband outlook on flexible and textile RF energy harvesting and wireless power transfer: from near-field to 5G

Wireless power transfer (WPT) and Radio Frequency (RF) energy harvesting (EH) are increasingly seen as an enabling technology for power-autonomous Internet of Things (IoT) [1, 2]. RFEH and WPT are a particularly attractive power source for flexible, printed, and e-textile systems due to their compatibility with standard fabrication processes, abolishing the need for specific materials and transducers. This work provides an overview on flexible WPT at multiple frequencies (6.78 MHz to 26 GHz) and techniques from near-field WPT to Millimetre-wave WPT and RFEH.