Electromagnetic Design of an Inductive Wireless Power Transfer System for Endoscopic Capsule

The power and energy demand for the instrumentation implemented in endoscopy capsules is such that a power supply from electrochemical cells is inappropriate. In this paper the electromagnetic design of the Wireless Power Transfer (WPT) system of the autonomous multimodal implantable endoscopic capsule designed within the project AUTOCAPSULE is firstly described. In particular, the design of the inductive link between the transmitting and the receiving coils is presented by showing the main involved parameters. The choice of wire and number of turns for transmitting and receiving coils is discussed by taking into account the power transferred to the load and the design constraints on available space and tissue absorption. The problem of patient exposure to non-ionizing electromagnetic fields is treated with a 3-D FEM simulation. The WPT conceived system allows to satisfy the project requirements, i.e., a power transfer to the end-user of 150 mW at a distance up to 15 cm, showing as well compliance with SAR regulations.