Wireless power supplying flexible and wearable systems

In this paper we first overview CAD techniques for the optimization of energy harvesting and storage systems designed to exploit EM sources available in the ambient. For a successful operation an accurate prediction of the minimum received power is needed to ensure the rectifier turn-on and the start-up of the energy storage control circuit. The proposed method is based on a first step dedicated to the simulation/optimization of the rectenna nonlinear regimes to determine reference values of the received signals. The second step is carried out in the time domain and is devoted to the optimization of the power management unit with the goal of dynamically keeping the rectenna at its optimum loading conditions. During this process the dispersive behavior of rectenna is accurately accounted for. The procedure validation is then discussed for a textile multi-layer multi-frequency rectenna using fabric for both the substrates and the metallic layers. The presented system is thought to recover RF energy upon user request from GSM 900, GSM 1800 and WiFi sources.