Implementation of wireless remote controller with the function of tracking inner coil position for implantable active medical devices

Abstract

A popular technique for wireless power transfer and data communication between fully implantable active medical devices and base stations is inductive coupling. A weakness of current technology means that the magnetic coupling coefficient is sharply decreased by variations in the distance and misalignment between two coils. This can result in degradation of communication and efficiency of power transfer between implants and external devices. In this paper, a method to track the coil position of the implant device using a 3-axis magnetic sensor module in the wireless remote controller has been proposed for efficient power transfer and robust data communication. The magnetic sensor module is implemented for obtaining the magnetic flux vector of the magnet in the middle of the inner coil. Based on the obtained magnetic flux vector, the pseudo-distance vector between the inner coil and the outer coil can be calculated and the position of the inner coil can be tracked. From experiments to evaluate the performance of the implemented remote controller's ability to find the inner coil position, we found that our remote controller could track the position of the inner coil of the implant device with the averaged error range of 3.73 mm and increase to a maximum of about 30% above the minimal power requirement for charging a battery of the mock-up implant device. It is expected that the implemented remote controller can be used for implantable active medical devices such as fully implantable middle ear hearing devices.