Capacitive Detuning Optimization for Wireless Uplink Communication in Neural Implants

This study presents a wireless energy and data transfer system for neural implants with an emphasis on epilepsy monitoring. A wireless uplink data transmission system is built upon a remote powering system based on magnetic coupling which has been implemented previously. Uplink communication from the implant unit to the external base station is realized by shifting the resonance frequency of the load coil in the implant side. Effect of different detuning capacitances on power transfer efficiency and energy per bit is investigated. The in-vitro measurements of the system exhibits 32% power transfer efficiency while transferring 1 Mbit/s data from 10 mm distance at 8.5 MHz using a detuning capacitance of 120 pF. Furthermore, an optimization based on data rate, energy per bit, and power transfer efficiency has been proposed for the resonance frequency shift keying method.