Optimization of Miniaturized Wireless Power Transfer System to Maximize Efficiency for Implantable Biomedical Devices

Development in implantable biomedical devices leads to the need for improving the efficiency of wireless transmission of power as well as miniaturization. This paper presents an optimized WPT system for achieving maximum efficiency for miniaturized implantable sensors. For the optimization of the coil design to achieve the maximum efficiency taking into account all the design constraints (e.g., maximum allowable size, trace width, spacing, tissue losses), an optimization algorithm and tool is developed using the Python language. Unlike the conventional optimization approach, where the frequency is usually a user-defined input, the proposed optimization tool inputs the frequency as a variable and the efficiency is maximized by computing the optimum frequency. To improve the matching of the transmitting coil to a 50 Omega load and thus to improve the efficiency, an L-shaped matching network consisting of an inductor and a capacitor is designed in the TX module. The inclusion of the matching network shows an improvement of over 21% of the efficiency of the WPT system over 10 mm of distance through air. The analytic calculation and simulation results are also validated via measurements.