Optimization and Analysis of High-frequency Data Receiver Coil for Artificial Retina

Abstract

High-frequency coils are vital parts of the wireless data transfer system of implantable electronics for achieving higher data rates. Coil structure and its geometrical parameters are the deciding factors of the optimized coil design. In this paper, the physical parameters of the coil are optimized to resonate at a high frequency. A simple parametric approach is used to extract the physical parameters of the coil for optimizing the coil features at high frequency using MATLAB. The key challenges associated with the disparity in coil characteristics after implantation in the eye are being investigated. Tissue layers that mimic the human eyeball are modelled using HFSS software. The coil is simulated in the tissue environment to evaluate the electrical characteristics of the coil in the biological medium. To validate the simulation model, the implant coil is characterized in the porcine eye to analyse the electrical behaviour of the coil in tissue media. The measured Q factor of the coil in the air is 19.69 and in the tissue is 3.3. Experimental results of the coil implanted in the porcine eye show that the resonant frequency of the coil is reduced by 20%, which limits the operation of the coil at higher frequencies when implanted. This exploratory study on the interaction of biological medium with the electrical behaviour of the coil can be used to predict energy losses in tissues and hence aid in devising compensation techniques for improving the data transmission efficiency of the artificial retinal system.