Wireless communication and power transfer system for intracranial neural recording applications

This study presents a system which provides a wireless solution to implant powering and bidirectional communication between a neural implant and an external base station. Wireless power transfer (WPT) is realized by using a 4-coil resonant inductive link at 8.6 MHz at a separation distance of 10 mm, which is the average human scalp thickness. Downlink communication at 10 kbps is performed on the same frequency as the WPT by ASK modulation. Uplink communication at 1.8 Mbps which carries digitized neural data is realized by using an integrated transmitter and a discrete receiver in 426-432 MHz band. The transmitter is composed of a cross-coupled symmetrical LC voltage controlled oscillator which is brought to resonance with a loop antenna instead of an integrated inductor. The loop antenna serves also for radiation.