Design and analysis of wireless power transfer system using flexible coil and shielding material on smartwatch strap

In this paper, we propose and analyze a smartwatch strap wireless power transfer (WPT) system using flexible PCB coils and magnetic field shielding materials. To ensure the sufficiency power delivery, we addressed the changes in impedance of the curved WPT coil system using 3D EM simulation and Z-parameter analysis. Using the proposed scheme, we achieved coil to coil power transfer efficiency of 50%.