Position and angular misalignment analysis for a wirelessly powered stimulator

This study investigated the effects in inductive coupling of wireless power due to the contribution of both positional and angular misalignment between the transmitter and implanted stimulator antennas. The implant antenna radius was limited to 1.5 cm for endoscopic implantation while the transmitter coil radius was kept at 21 cm in order to transfer sufficient power for tissue stimulation. The power transfer distances between the two antennas examined were 5, 7 and 10 cm, typical for stimulator implant applications. Theoretical radiation patterns were examined with magnetic field distribution and compared with measured output voltages. Experimental results agreed well with the theoretical models. The optimal location for maximal output power in the receiver was identified with respect to different angular misalignments and distances. The method can guide the re-adjustment strategy of the transmitter coil worn by the patient after implantation and during therapy.