Influence of system integration and packaging for a wireless neural interface on its wireless powering performance

In an integrated wireless neural interface based on the Utah electrode array, the implanted electronics is supplied with power through inductive coupling between two coils. This inductive power link would be affected by conductive and dielectric media surrounding the implant coil. In this study, the influences of the integration of implant coil on silicon based IC/electrode, thin film parylene coating, and physiological medium surrounding the coil were investigated systematically and quantitatively. A few different versions of implant coils were made by winding fine wire with a diameter of around 50 microm. The parasitic influences affecting the inductive power link were empirically investigated by measuring the electrical properties of coils in different configurations and in different media. The distance of power transmission between the transmit and receive coils was measured when the receive coil was in air and immersed in saline solution to simulate an implanted physiological environment. The results from this study suggest factors to be considered when integrating and encapsulating implantable devices that employ inductive power link.