Enhanced Inductive Link Using Perpendicular Transmitting Coils in Wireless Power Transfer for Visual Implants

Coil misalignment is a serious problem in wireless power transfer (WPT) for visual implants since the relative positions of the receiving coils fixed in eyes are varying with time, which can lead to degradation of power transfer efficiency. To enhance the inductive link and improve the misalignment tolerance, this paper presents a novel WPT system with perpendicular transmitting coils. It shows that two perpendicularly placed transmitting coils can effectively weaken the effect of variation of coupling coefficients due to coil misalignment. Through calculation and circuit analysis, system optimization method for the optimal turns of the transmitting coils is conducted. Compared to a conventional WPT system under the same condition, the proposed system has better misalignment performance and meets the requirements for body safety.