Maximizing Wireless Power Transfer to Intraocular Implants Under Unconstrained Eye Movements

Inductive wireless power transfer empowers microelectronic systems to be implanted in spatially constrained anatomic areas. Due to the need to deliver therapeutic or diagnostic function to sensitive areas, such as the eye, batteries become impractical for reasons of thermal and mechanical safety. In this paper we discuss the requirements and optimization techniques to power an intraocular implant through an inductive coil in the surface of the eye, particularly in the case of a retinal prosthesis. We design and characterize transmitting and receiving inductive coils. Subsequently, through the use of a custom 3D printed mechanical test frame, we characterize the power transfer efficiency at the appropriate geometric parameters. Furthermore, the effect of misalignment, axial displacement, and rotation due to eye movements on power transfer efficiency are quantified in air and through a fragment of animal tissue. These results can be used to model and mitigate movement related power fluctuations.